Contents
2008
Volume: 28 Issue s2
84 Article(s)
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Fiber Optics and Optical Communications
An Adaptive Immune Evolutionary Algorithm Using in Restoration Optimization of All-Optical Network
Han Yishi, Ao Zhanbin, and Wang Yufei
This paper introduced a new evolutionary algorithm — adaptive immune evolutionary algorithm (AIEA) for restoration optimization of all-optical network (AON), aim to design the virtual topology, globally optimize re-routing and throughput in the AON. By introducing adjusting parameters, the process of the algorithm can This paper introduced a new evolutionary algorithm — adaptive immune evolutionary algorithm (AIEA) for restoration optimization of all-optical network (AON), aim to design the virtual topology, globally optimize re-routing and throughput in the AON. By introducing adjusting parameters, the process of the algorithm can be adapted to the AON dynamically, so as to improve throughput and avoid premature or local convergence. Besides, the algorithm considers optimization of resource utilization in AON at the same time so as to decrease the blocking probability when failures happen in the networks. The results show AIEA has the best optimized performance in performance of optimization restoration in AON of MESH topology networks..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 157 (2008)
Using Crosscorrelation to Detect and Control the Accurate Delay Time of Ultrafast Pulses
Hao Xin, Zhu Qihua, Wang Xiao, Wang Xiaodong, Geng Yuanchao, Zhang Ying, Zhou Kainan, and Huang Zheng
In the high-power ultrafast laser system, interaction between the high-power laser and target substance would produce plasma,in order to know the evolvement of the plasma,the delay time between probe laser and main laser should be controlled accurately, in which the precision of delay need to be several picoseconds eveIn the high-power ultrafast laser system, interaction between the high-power laser and target substance would produce plasma,in order to know the evolvement of the plasma,the delay time between probe laser and main laser should be controlled accurately, in which the precision of delay need to be several picoseconds even several femtoseconds. Therefore an instrument, which was based on the ultrafast pulses crosscorrelation theory, by utilizing the sum frequency generation effect, CCD to collect the spatial intensity distribution of sum frequency beam, was designed. By measuring the shift of curve peak, the delay between fundamental beams can be calculated, the fundamental beams can be accurately delayed by controlling the optical layout. The conformation of delay instrument was described, the principle of the ultrafast pulses crosscorrelation measurement was discussed, the relationship between the delay time and the shift of the curve peak was analyzed theoretically. The influence on the measure precision caused by the angle of fundamental beams was discussed numerically, to reach a much more accurate delay time, we can change the nonlinear crystal according to the beam angle..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 162 (2008)
Communication Rate and Error Rate in the Quantum-Key-Distribution System
Jiao Rongzhen, Feng Chenxu, and Tang Shaojie
The performance of various quantum-key-distribution systems is analyzed using 1.55-μm up-conversion single-photon detector. Important parameters such as communication rate, error rate, quantum efficiency and dark count rate are discussed. It is shown that quantum efficiency depends on the pump power, and that 1.55-μm uThe performance of various quantum-key-distribution systems is analyzed using 1.55-μm up-conversion single-photon detector. Important parameters such as communication rate, error rate, quantum efficiency and dark count rate are discussed. It is shown that quantum efficiency depends on the pump power, and that 1.55-μm up-conversion single-photon detector has great advantage over the InGaAs avalanche photodiodes detector. The analysis is based on the secure communication rate and error rate as a function of distance for three quantum-key-distribution(QKD) protocols: the Bennett-Brassard 1984, the Bennett-Brassard-Mermin 1992, and the differential-phase-shift-keying protocols. We consider that the secure communication rate of the three protocols against an arbitrary individual attack, including the most commonly considered intercept-resend and photon-number splitting attacks, and concluded that the simple and efficient differential-phase-shift-keying protocol allows for more than 200 km of secure communication distance with high communication rate..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 167 (2008)
Estimation of Transmission Delay in the Accurate Time Transfer System Based on Optical Link
Lai Xianzhu, Zhang Baofu, Lu Lin, and Xie Chang
The time synchronization accuracy depends on the accuracy of the transmission delay measurement of the time signal in the time transfer system. The transmission delay is always achieved by measuring the round-trip path delay using the outgoing and incoming path. But it incurs error due to the chromatic dispersion of thThe time synchronization accuracy depends on the accuracy of the transmission delay measurement of the time signal in the time transfer system. The transmission delay is always achieved by measuring the round-trip path delay using the outgoing and incoming path. But it incurs error due to the chromatic dispersion of the fiber in the time transfer system based on optical cable. A method to count the difference in transmission delay between the outgoing and incoming path is proposed based on the dispersion of the G.652 fiber. The error caused by fiber dispersion can be eliminated when the wavelength of optical signal in the round-trip is around 1.55-μm by using this method, which can achieve the accurate transmission delay of the signal..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 170 (2008)
Discussion on Multiple User Interference Suppressing Based on Maximal Value Decision for OCDMA System under Multiple Noise Existing Background
Li Xiaobin, and Li Chuanqi
In term of the problem of multi-user interference existing in optical code division multiple access (OCDMA) system, a parallel interference suppressing method for OCDMA communication based on maximal value decision is examined, and the situation is that APD is adopted and multiple noises exist. The fundamental is stateIn term of the problem of multi-user interference existing in optical code division multiple access (OCDMA) system, a parallel interference suppressing method for OCDMA communication based on maximal value decision is examined, and the situation is that APD is adopted and multiple noises exist. The fundamental is stated, that is it avoids the case no optical pulse existing while bit 0 is transmitted by adopting a spread spectrum code and its shift as the address codes of bit 0 and bit 1, respectively; and maximal value decision instead of threshold decision is adopted as decision circuit. Optical orthogonal codes is applied as address codes, APD is used as opto-electro detector, and bit error probability of novel system is derived and analyzed. Simulations based on the expression are done and comparison with other multi-user interference suppressing methods is made. The results show that the effect of the method to suppress multiple access interference is changed with different number of system users and code weights; compared with other effective methods such as double hard-limiters method or multiple-bit transmitted method, the method is superior to multiple-bit transmitted method, it is also superior to double hard-limiters method in the case received power is low. So, the method can suppress multi-user interference effectively..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 174 (2008)
Performance Analysis and Research of LDPC code in Optical Communication System
Liao Wei, and Liu Jingao
Low-density parity check code(LDPC)is a good approximation of the Shannon limit. It has decoding with low complexity and flexible structure. It was the hot-spot of channel coding field in recent years so that it has the widespread application prospect in the optical communication system. In the view of LDPC long code bLow-density parity check code(LDPC)is a good approximation of the Shannon limit. It has decoding with low complexity and flexible structure. It was the hot-spot of channel coding field in recent years so that it has the widespread application prospect in the optical communication system. In the view of LDPC long code based on irregular Tanner graph which has good performance and its application in the optical communication system, this paper constructed several LDPC codes,and used BP algorithm to carry out computer simulation in the AWGN channel and under the BPSK modulation. According to the BER and the FER curve of regular and irregular LDPC code, not only coding and decoding but also performance are analyzed and compared.At last, the paper makes some suggestion as to the LDPC code with the practical value in the optical communication system. Through the theoretical analysis and simulation results show that the LDPC code has a good performance, and can save hardware costs so that it is suitable in optical communication system and can be used as a super-forward error correction candidate code..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 180 (2008)
A Variational Study on the Propagation Equation of Bright Soliton-Like Pulse Under the Influence of the Fifth-Order Nonlinearity in Optical Fiber
Liu Wenjun
When considering the influence of the fifth-order nonlinearity on the propagation of optical pulse, the propagation of bright soliton-like pulse in optical fiber satisfies the following nonlinear Schrdinger equation with the fifth-order nonlinear term. By using of He′s semi-inverse method, the variational form to this When considering the influence of the fifth-order nonlinearity on the propagation of optical pulse, the propagation of bright soliton-like pulse in optical fiber satisfies the following nonlinear Schrdinger equation with the fifth-order nonlinear term. By using of He′s semi-inverse method, the variational form to this equation is established firstly. Then, the Sech expression formula to the traveling wave solution of the equation is derived by utilizing He′s variational method. At the same time, motivatied by He′s exp-function method, a new Guass expression formula of the solution is obtained. On the one hand, one can further study the influence of fifth-order nonlinearity on the propagation of pulse in optical fiber based on these expression formulae. On the other hand, the solution process reveals that He′s variational method is an easy, concise and effective method to solve nonlinear evolution equations arising in mathematical physics..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 184 (2008)
Power Calculation and Communication Distance Equivalent Demonstration for Optical Communication
Liu Zhiying, Hu Yuan, Zhang Lei, Gao Tianyuan, and Wang Zhijian
There are advantages of small volume and light weight in optical communications. For the smooth communication of long distance, the transmitting power should be calculated with higher security efficiency. The constraints of transmitting power, beam divergence and the detecting sensitivity on the communication distance There are advantages of small volume and light weight in optical communications. For the smooth communication of long distance, the transmitting power should be calculated with higher security efficiency. The constraints of transmitting power, beam divergence and the detecting sensitivity on the communication distance and performance is analyzed. A calculation equation with higher security efficiency is proposed. When the error rate is determined, the minimum detecting power could be calculated by the relationship with signal-to-noise ratio (SNR). In the real communication system, the minimum detecting power could be tested by the relationship with the detecting sensitivity. The calculated equation is verified through the agreement of above two results. The communication distance demonstration is realized by the calculation equation with higher security efficiency..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 188 (2008)
Node Queueing Mechanism of Video Transmission in Optical Networks
Lu Min, Zhang Ping, and Li Zhengbin
The queueing management strategy of quality of service(QoS) was analyzed as a key point. First, the performances of first in first out (FIFO) queueing mechanism and priority queuing (PQ) mechanism were obtained and compared. It was found that PQ mechanism could reduce the average delay of the higher priority traffic, bThe queueing management strategy of quality of service(QoS) was analyzed as a key point. First, the performances of first in first out (FIFO) queueing mechanism and priority queuing (PQ) mechanism were obtained and compared. It was found that PQ mechanism could reduce the average delay of the higher priority traffic, but the time jitter was still not under control. Therefore, an improved algorithm based on PQ mechanism was developed to solve this problem. The simulation results showed that the delay jitter was decreased significantly by the improved algorithm, and the delay jitter was improved when the data packets of different initial time delay were queued in the nodes..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 191 (2008)
Reliability and Real-time Assurance of Fly-by-light Network for Flight Control System
Luo Jiarong, Luo Xuan, He Hao, Jin Yaohui, Huang Haoyi, and Wu Jianmin
A survey is made on several traditional topologies of fly-by-light(FBL) network. Based on the comparison of their reliability and real-time performance, a mesh optical switching network topology with 256 nodes is chosen. The redundancy topology gives the ability to sustain 3 link faults, which assures the reliability oA survey is made on several traditional topologies of fly-by-light(FBL) network. Based on the comparison of their reliability and real-time performance, a mesh optical switching network topology with 256 nodes is chosen. The redundancy topology gives the ability to sustain 3 link faults, which assures the reliability of network. The seriousness of the network failure can be measured by the number of link faults. And when several link faults occur at the same time, it must also be measured by the contiguity degree among the faults. A simulation is taken to test the end-to-end latency under all network failure situations. The simulation results show that even when some serious fault occurs, the number of hops of the end-to-end route increases slightly. So it still meets the real-time communication requirements..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 196 (2008)
Analysis on the Adaptability of Polarization Mode Dispersion Adaptive Compensation System on Different Modulation Formats
Wang Shaokang, Xi Lixia, Fang Guangqing, Zhao Xinyuan, and Zhang Xiaoguang
The adaptive compensation method of polarization mode compensation (PMD) has been studied in depth. Degree of polarization was sampled as the feedback signal and particle swarm optimization (PSO) algorithm was applied as the feedback control method in the adaptive compensation system. The effect of the compensation sysThe adaptive compensation method of polarization mode compensation (PMD) has been studied in depth. Degree of polarization was sampled as the feedback signal and particle swarm optimization (PSO) algorithm was applied as the feedback control method in the adaptive compensation system. The effect of the compensation system upon signals of different modulation formats was examined and carried into comparison experimentally. The quality of the transmission signal being severely deteriorated, signals of different modulation formats were compensated productively with bit error ratio (BER) improved enough to satisfy the demand of optical communication systems (10-9). Thus the insensibility of the productiveness of PMD adaptive compensation system towards signals of different modulation formats was experimentally proved. Besides, the NRZ possess a certain power penalty over each other modulation format, while the receiving performance of signal of RZ50 was the best..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 201 (2008)
Optical Fiber Sensor Wavelength Demodulation System Based on Broadband Light Source
Wang Xiaona, Song Shide, and Yu Qingxu
Research work has been done in optical fiber sensor demodulation system based on broadband light source. Multi-FBGs are used as wavelength reference and fiber Fabry-Pérot tunable filter (FFP-TF) is used as wavelength selection device in the system. A non linear fitting based on cubic polynomial is adopted as the bResearch work has been done in optical fiber sensor demodulation system based on broadband light source. Multi-FBGs are used as wavelength reference and fiber Fabry-Pérot tunable filter (FFP-TF) is used as wavelength selection device in the system. A non linear fitting based on cubic polynomial is adopted as the best fitting algorithm to convert scanned voltage of FFP-TF sawtooth wave to scanned transmission wavelength, which can solve the systemic error caused by the non linear relation between the wavelength and scanning voltage of FFP-TF, and then get higher demodulation resolution. In the experiment, five reference FBGs are used in the demodulation system. One FBG sensor demodulation result shows that wavelength resolution of measurement FBG is 3.5 pm for a short time, and long-term stability is 7 pm. An EFPI optical fiber strain sensor is tested with the demodulation system, which shows the strain sensitivity of 2.41 nm/με, besides, there is good linear relation between strain and wavelength with a linear correlation coefficient of 0.99991..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 205 (2008)
Burst Contention Resolution Strategy Based Delay Preemption
Yang Jiuru
In optical burst switching networks, it has been regarded as a convenient and efficient scheme for contention resolution that the contended bursts are buffered in the fiber delay lines (FDLs). Based on the prereservation model, a novel scheme namely delay preemption (DP) is proposed to avoid contention, and the blockinIn optical burst switching networks, it has been regarded as a convenient and efficient scheme for contention resolution that the contended bursts are buffered in the fiber delay lines (FDLs). Based on the prereservation model, a novel scheme namely delay preemption (DP) is proposed to avoid contention, and the blocking performances of full and partial DP mechanisms are compared. To support the diffserv, the research of DP mechanism is developed in the two-priority system. The blocking model of two-priority system is built up. And the DP mechanisms in terms of blocking and delay are analyzed. The simulation results show that for the high priority bursts, a low burst blocking probability is obtained by using the DP mechanism, which is about two-order level smaller than that of the low priority bursts. Besides, owing to the fixed length of FDL, the requirement of data bursts on delay is guaranteed as well. When the traffic load ρ is 1.0, the average delay time of high priority bursts is confined within 10 μs..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 209 (2008)
A General Timeslot Scheduling Mechanism for Timeslot Ring Network
Yue Peng, Wen Aijun, Liu Zengji, and Zhang Zhiqing
A distributed timeslot scheduling for ring (DTSR) is presented for all timeslot ring networks based on the destination node stripping. DTSR achieves the dynamic information collection of “starve” nodes in the ring, coordinates the time occupied by nodes, and ensures the fairness each node with increasing a simple fieldA distributed timeslot scheduling for ring (DTSR) is presented for all timeslot ring networks based on the destination node stripping. DTSR achieves the dynamic information collection of “starve” nodes in the ring, coordinates the time occupied by nodes, and ensures the fairness each node with increasing a simple field in timeslot control header transmitted circularly in one-way channel. After “starve” nodes are found in ring, DTSR ultilizes the timeslot ring network with spatial reuse, transfers their data to other nodes which are not via “starve” nodes, and therefore makes full use of the ring network resources. In addition, DTSR mechanism has a good convergence of the algorithm, and a smaller access delay than the traditional methods. The performance of DTSR is simulated and compared with the other typical timeslot ring networks..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 213 (2008)
Traffic-Grooming in WDM Network under Physical Constraints
Zeng Ling, Xu Shizhong, Wang Sheng, Wang Xiong, Li Lemin, and Zhou Kaiyu
The traffic demands in optical networks are often irregular associated with various physical constraints such as SRLG disjoint, taboo link, taboo node and so on. The virtual topology design methods in the literature could hardly to solve traffic grooming problems with multiple kinds of constraints. We propose a packingThe traffic demands in optical networks are often irregular associated with various physical constraints such as SRLG disjoint, taboo link, taboo node and so on. The virtual topology design methods in the literature could hardly to solve traffic grooming problems with multiple kinds of constraints. We propose a packing grooming with max revenue algorithm (MRA). The traffic demands are placed directly in the physical topology, which are treated as low-granularity single-hop-pipes. To save the low-granularity switch capacity in the intermediate nodes, MRA checks which demands could be packed into high-granularity multi-hop potential pipes. Among the high-granularity potential pipes, we search the maximum set of potential pipes which do not collide with each other by a max-revenue approach and instantiate them. Numerical results show that MRA algorithm has better performance than existing algorithms in capacity and cost of network, and it could be used in large networks with more than one hundred nodes..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 219 (2008)
A New Modulation Method in Free Space Optical Communication: Circle Polarization Shift Keying
Zhao Xinhui, Yao Yong, Sun Yunxu, and Liu Chao
In free space optical communication (FSO), optical signals transmit in the open air link. Inevitably, received signals are influenced by atmosphere disturbance and background noise, so the reliability of FSO system is reduced. In order to restrain adverse effects of atmosphere disturbance, a new modulation method of opIn free space optical communication (FSO), optical signals transmit in the open air link. Inevitably, received signals are influenced by atmosphere disturbance and background noise, so the reliability of FSO system is reduced. In order to restrain adverse effects of atmosphere disturbance, a new modulation method of optical signal in FSO, which is named as circle polarization shift keying (CPOLSK), is proposed in this paper. In this modulation, two rotation states of circle polarization are used to denote “0” and “1” data , respectively, then the information transmission accomplished by transmitting rotation state time series. In the receiver, the signal is detected with difference method. The setting of CPOLSK is presented and the performance is analyzed. Compared with on-off-keying(OOK)and pulse position modulation(PPM) modulation methods, which are widely used in wireless communication systems, the CPOLSK modulation has more excellent capability in background noise suppressing and photodetector inherent noise limiting..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 223 (2008)
GMPLS-Based Fast Restoration Mechanism for Meshed Networks in ASON
Zheng Yanlei, Gu Wanyi, Huang Shanguo, Deng Yu, Wang Lei, and Liu Tao
As the introduction of generalized multi-protocol label switching(GMPLS) for control plane, the technology of automatic switched optical networks (ASON) provides optical transmission network with greater intelligence. Based on the view consistency of topology between control plane and transport plane, this contributionAs the introduction of generalized multi-protocol label switching(GMPLS) for control plane, the technology of automatic switched optical networks (ASON) provides optical transmission network with greater intelligence. Based on the view consistency of topology between control plane and transport plane, this contribution proposes a new network survival mechanism-double links restoration to solve the single optical node failure. The mechanism seeks to protect for the two links of the failure point by detours in GMPLS simultaneously. Through detailed analysis of the common link restoration and double link restoration(DLR), the paper quantitatively presents the scheme for signaling recovery time in these two cases. From the mathematical formulas, it can be concluded that DLR overcomes the disadvantages about long signaling establishment delay in presence of node failure traditionally. Some experimental descriptions for the different restoration mechanisms are illustrated. It verifies the effectiveness of the proposed mechanism..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 227 (2008)
Fourier Optics and Signal Processing
Peformance Analysis of All Optical Encoding and Decoding Based on Superstructured Fiber Bragg Grating
Chen Xiaogang, and Huang Dexiu
To evaluate correlation characteristics for superstructured fiber Bragg grating (SSFBG) based en/decoder in the optical code division multiple access (OCDMA) system, the effects on encoding and decoding of input pulse width, encoder-decoder wavelength mismatch and grating refractive index modulation amplitude are consiTo evaluate correlation characteristics for superstructured fiber Bragg grating (SSFBG) based en/decoder in the optical code division multiple access (OCDMA) system, the effects on encoding and decoding of input pulse width, encoder-decoder wavelength mismatch and grating refractive index modulation amplitude are considered. The theoretical results show that the degradation of en/decoder performance is obvious under the impact of increasing of input pulse width and encoder-decoder wavelength mismatch. In addition, there is a contradiction between correlation property and insertion loss of SSFBG en/decoder, it is need to select moderate refractive index modulation amplitude of SSFBG grating. The theoretical model of coherent time spreading phase coding OCDMA system based on SSFBG en/decoder is presented. Three different kinds of noise source are taken into account: multiple access interference (MAI) noise, beat noise and receiver noise. Moreover, the system performance degradation as a result of receiver’s bandwidth limitation is evaluated. Optical thresholder and turbo code are employed to improve the performance of coherent time spreading OCDMA system..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 1 (2008)
Research on Integration of Gray Code and Phase-shifting Coding Algorithm for 3D Shape Reconstruction
Cui Haihua, Liao Wenhe, Cheng Xiaosheng, Dai Ning, Guo Meishe, and Li Changchun
A novel combinated coding technology of Gray and phase-shifting is proposed. This coding algorithm combines advantages of Gray code and phase-shifting code. At first, Gray code is used to avoid the accumulation of error code. Then, the Gray code and phase-shifting code are combinated, they are respective as integral anA novel combinated coding technology of Gray and phase-shifting is proposed. This coding algorithm combines advantages of Gray code and phase-shifting code. At first, Gray code is used to avoid the accumulation of error code. Then, the Gray code and phase-shifting code are combinated, they are respective as integral and decimal part of the combination code, a infinite space segments of the view space is divided by this intergration and a high coding resolution is achieved. Morever, a code compensation algorithm is developed to overcome the usual two codeing errors for acquiring a correct code. At last, the experiments show that this optical coding algorithm is effective and robust to three-dimansional reconstruction..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 7 (2008)
Emission Spectrum Analysis for Air Plasma by Pulsed Streamer Discharge in Atmospheric Pressure
Dang Wei, Zhang Lianshui, Wang Bairong, and Liu Fengliang
The paper presented an experimental study on air plasma, which was produced in atmospheric pressure discharge system with two needle electrodes, by using emission spectrum method. The emission spectrum consisted of continuous spectrum background and discrete spectrum above the background. The continuous spectrum resultThe paper presented an experimental study on air plasma, which was produced in atmospheric pressure discharge system with two needle electrodes, by using emission spectrum method. The emission spectrum consisted of continuous spectrum background and discrete spectrum above the background. The continuous spectrum resulted from bremsstrahlung and recombination emission in the plasma. The discrete spectrum were assigned to fluorescence emission of N2 C3∏u →B3∏g ,N+,N,O. The upper electron configurations corresponding to N+ fluorescence were 2s22p(2P0)3p and 2s22p(2P0)3d, respectively and their energy levels located between 20 eV and 23.6 eV. Time resolved spectroscopy of N2(336.8 nm), N+(500.5 nm), N+(399.7 nm) fluorescence signals were also acquired. The results show that N2(336.8 nm) fluorescence appeared firstly, then N+(500.5 nm,399.7 nm) fluorescence showed up at the same time with about 25 ns delay. Based on time resolved measurement and related references, the paper analyzed N+ production channels..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 12 (2008)
Simulation Investigation for Phase-Shifts Transformation of Linearly Chirped Pulse from Frequency-Domain to Time-Domain
Dong Jun, Peng Hansheng, Wei Xiaofeng, Hu Dongxia, Wang Xiaodong, Zhou Wei, Zhao Junpu, Yang Yisheng, and Cheng Wenyong
In ultrafast laser-matter interaction experiments, single-shot, real-time spectral interferometry is the significant for rapid and accurate measurement. Based on spectral interferometry and time-frequency linear relation of linearly chirped pulse, the method that spectral phase-shifts of chirped pulse are transformed tIn ultrafast laser-matter interaction experiments, single-shot, real-time spectral interferometry is the significant for rapid and accurate measurement. Based on spectral interferometry and time-frequency linear relation of linearly chirped pulse, the method that spectral phase-shifts of chirped pulse are transformed to temporal phase-shifts in a directly frequency-to-time mapping mode is investigated theoretically. Restrictive conditions of this method are derived. The transformation process of phase-shifts is simulated. The results show that phase-shifts obtained is characteristic of temporal change, and this approach has single-shot measurement ability, which in perturbation and fixed pulse bandwidth, the transformation error of phase-shifts is reduced, as appropriate increase of the chirp of probe pulse..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 16 (2008)
Theory Study on Beam Wander for Laser Beam Propagation through Non-Kolmogorov Turbulence
Du Wenhe, Tan Liying, and Ma Jing
Free-space laser system performance is limited by atmospheric turbulence that has been described for many years by Kolmogorov’s power spectral density model because of its simplicity. However, many inland and overseas experiments concerning non-Kolmogorov atmospheric turbulence have showed recently that Kolmogorov’s thFree-space laser system performance is limited by atmospheric turbulence that has been described for many years by Kolmogorov’s power spectral density model because of its simplicity. However, many inland and overseas experiments concerning non-Kolmogorov atmospheric turbulence have showed recently that Kolmogorov’s theory is sometimes imcomplete to describe atmospheric turbulence statistics correctly, in particular in portions of the troposphere and stratosphere. It is the first problem to investigate the effect of non-Kolmogorov on the propagation of light in order to know completely the effect of atmospheric turbulence on free-space laser communications. In this paper using the non-Kolmogorov turbulent power spectral density, we derived the variances of beam wander of the convergent and collimated beams, which are analytic and concise, and then analyzed the formulas..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 20 (2008)
Double Phases Rotated and Translated Sub-Pixel Digital Image Stabilization Algorithm
Du Dengchong, Jiang Xiaoyu, and Yao Jun
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 24 (2008)
The Influence of Surface Scattered Light to the Measurement of Laser Displacement Sensor Based on Triangulation
Gao Zhan, Wu Sijin, Han Qiang, Chen Shiqian, and Feng Qibo
The accuracy of laser displacement measurement based on triangulation is affected not only by optical source, detector and mechanical construction, but also have relation with measured surface features such as luster, material, roughness, inclination and environment. Some researchers have presented some methods to imprThe accuracy of laser displacement measurement based on triangulation is affected not only by optical source, detector and mechanical construction, but also have relation with measured surface features such as luster, material, roughness, inclination and environment. Some researchers have presented some methods to improve the measurement accuracy, which based on the same surface features. In this paper the scattered light field on the measured surface is analyzed with random walk theory. The relations of scattered light intensity and scattered light detected angle on different roughness surface are shown. Because the scattered light detected angle of sensor we made is between the 15°to 25°, the value of scattered light angle is assumed to be 20°, the maximum change of scattered light intensity on three different roughness surface is roughly 300% through the simulation. These model and results are helpful to the optimal design of the laser displacement sensor and improvement of measurement accuracy..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 29 (2008)
Comparing the AIRS Temperature and Water Vapor Retrieval Profile with COSMIC
Guan Li, Mu Fengjun, and Zhao Fenghuan
Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) provides a new approach to remote sensing the atmospheric profile for areas difficult to periodically measure. Comparing the vertical profile of atmospheric temperature and water vapor derived from COSMIC and Atmospheric InfraRed Sounder (AIConstellation Observing System for Meteorology Ionosphere and Climate (COSMIC) provides a new approach to remote sensing the atmospheric profile for areas difficult to periodically measure. Comparing the vertical profile of atmospheric temperature and water vapor derived from COSMIC and Atmospheric InfraRed Sounder (AIRS) retrievals with the collocated European Center of Medium-range Weather Forecasts (ECMWF) and National Centers for Environmental Prediction (NCEP) reanalysis values and radiosonde observations is described in detail in this paper. The results show that the retrievals derived from COSMIC with the feature of global covering, high precision and vertical resolution, low consuming, quasi-real time and all-weather measurement are more close to radiosonde observations relative to AIRS retrievals, at the same time COSMIC retrievals can provide the atmospheric profile structure more detail. The COSMIC shortcoming is the detect height be limited by occultation observation, so it cannot acquire the atmospheric information of low sky. Though AIRS has the better retrieval precision in clear sky it still cannot be used to detect cloudy conditions..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 33 (2008)
Holographic Phase Calibration for Fiber Interferometric Imaging Array
He Yuntao, Jiang Yuesong, and He Ye
A new approach based on holographic technique was proposed with photorefractive crystal for phase error calibration in fiber interferometric imaging arrays. The principle of fiber interferometric imaging arrays and the transmission of phase information were discussed first. The model of phase error was set up for a oneA new approach based on holographic technique was proposed with photorefractive crystal for phase error calibration in fiber interferometric imaging arrays. The principle of fiber interferometric imaging arrays and the transmission of phase information were discussed first. The model of phase error was set up for a one dimension linear array system. The particular process of holographic phase calibration with photorefractive crystal was as follows: the shutter before the reference beam and the shutter before the CCD camera were kept on and off by turns, which respectively made for the diffractive grating writing formed by interfering of fiber beam and reference beam, and for the diffraction and phase shift of the fiber beam. Finally the imaging simulation using un-calibrated, the purposed approach and the redundant baseline spacing calibration corresponded was compared based on the 1D fiber interferometric array with phase errors..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 38 (2008)
Graph-Cut-Based Stereo-Matching Algorithm Using Image Segmentation
Hu Chunhai, and Xiong Ying
Stereo-matching is an algorithm that through searching the corresponding relations between the projection images’ pixels of the same scene on different visual point, gains a disparity map of the scene finally. This paper presents a graph-cut-based stereo-matching algorithm using image segmentation on the basis of in-deStereo-matching is an algorithm that through searching the corresponding relations between the projection images’ pixels of the same scene on different visual point, gains a disparity map of the scene finally. This paper presents a graph-cut-based stereo-matching algorithm using image segmentation on the basis of in-depth study on the images matching algorithms. In proposed algorithm, the reference image is divided into segments. Then modeling disparity is built inside a segment by a planar equation. A set of disparity layers is extracted from initial disparity segments in a clustering process. A global energy function is constructed. Robust minimization of the cost function is achieved by graph-cut-based optimization. The proposed algorithm produces good-quality results, especially in regions of low texture and close to disparity boundaries. The expensive computing cost for traditional global algorithms can also be reduced. Experiments demonstrate that the algorithm can meet both demands for high resolution and real time..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 43 (2008)
A New Color Correction Model for Scanning Input Image Based on Yule-Nielson Equation
Li Xinwu
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 48 (2008)
An Arithmetic of De-Interleaving and Identifying of the Laser-Guided Weapon Signal
Liang Jing, and Zhou Dong
According to the coding technology of the laser guidance weapon, it is necessary to carry through code identifying and pulse forecast technology for effective laser jamming. The signal de-interleaving and code identifying were deeply discussed by analyses of the coding technology. Based on the PRI arithmetic of the radAccording to the coding technology of the laser guidance weapon, it is necessary to carry through code identifying and pulse forecast technology for effective laser jamming. The signal de-interleaving and code identifying were deeply discussed by analyses of the coding technology. Based on the PRI arithmetic of the radar signal, a new arithmetic of de-interleaving and identifying of the signal laser-guided was advanced, which included the process of de-interleaving and identifying of the signal. This arithmetic achieved the aim of code identifying, which has been validated by Matlab. A sample project of this interfere process was implemented on FPGA and the flow was mentioned in this paper..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 53 (2008)
Design of a Super-FEC Code Based on Low Density Parity Check Code in Optical Communication System
Liao Wei, Wu Xiang, and Liu Jingao
The effect of optical fiber transmission (dispersion, PMD and nonlinear effects, etc.) will seriously affect the transmission speed and further improvement of the distance. Consequently, it is essential to work out new super forward error correction (Super-FEC) codes with better performance so that higher coding gain aThe effect of optical fiber transmission (dispersion, PMD and nonlinear effects, etc.) will seriously affect the transmission speed and further improvement of the distance. Consequently, it is essential to work out new super forward error correction (Super-FEC) codes with better performance so that higher coding gain and better error correction performance will be received. This paper briefly introduced the low density parity check (LDPC) codes, and then proposed a SFEC code based on LDPC code in optical communication system. The novel LDPC(3969,3720) code with 6.68% redundanc was constructed., and the simulation result of the FEC code was showed up. It not only compared with those of the RS(255,239)code and BCH(3860,3824)+BCH(2040,1930) code, but also analyzed and discussed the problem that the encoding and decoding of LDPC circuit design and implementation. Through the theoretical analysis and simulation results show that this super-FEC code has a good performance,and can save hardware costs so that it is suitable in optical communication system and can be used as a super-FEC candidate code..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 58 (2008)
Study on The Transport Model Based on Atmosphere Scattering Theory in Ultraviolet Communication
Liu Ye, Xu Zhiyong, and Wang Jingyuan
Aiming at the single scattering model cannot figure how the ultraviolet communication was affected by different weather. Twice scattering model was put forward combined with the atmosphere scattering theory after studying the single scattering model. Phase function for Rayleigh and Mie scattering was studied in severalAiming at the single scattering model cannot figure how the ultraviolet communication was affected by different weather. Twice scattering model was put forward combined with the atmosphere scattering theory after studying the single scattering model. Phase function for Rayleigh and Mie scattering was studied in several weather conditions. After being scattered by particles, UV’s energy density distribution was simulated, and then the performance of ultraviolet communication system was simulated combining with particle’s thickness effectively. Simulation results indicate that non-line sight of communication is realizable, and twice scattering model can be used in different weather condition. Furthermore, the attenuation of UV signal is very sharp in rain and fog, which restricts the receiver apex angle comparatively, and that it is appropriate to UV communication in good weather, under which the receiver apex angle can reach 180°. Weather factor is more important in long-distance communication..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 62 (2008)
Analysis of the Effects of Atmosphere Scattering on Photon Polarization Degree
Ma Lizhen, Gu Yongjian, Shi Peng, and Li Xinhu
By using matrix to describe the polarization characteristic of photon and atmosphere scattering theory, the relationship between the polarization degree of four different polarized photons in “BB84 protocol” after single scattering and the forward scattering angle is analyzed. It is shown that single scattering does noBy using matrix to describe the polarization characteristic of photon and atmosphere scattering theory, the relationship between the polarization degree of four different polarized photons in “BB84 protocol” after single scattering and the forward scattering angle is analyzed. It is shown that single scattering does not have influence on photon polarization state, while the degree of linear and circular polarization are changed, especially, those of the perpendicular polarized photon are changed obviously. Also, it is founded that linear polarization degree of four different polarized photons keep unchanged when scattering angle is less than 0.25 rad, and the quantum information is still survive at the same time, we study the influence of atmosphere scattering on different wavelength polarized photons, it is shown that the polarization degree of longer wavelength photon change less than that of short wavelength photon..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 68 (2008)
Signal Processing of Optical Coherence Method Used to Measure Molecular
Sun Yifei, Zhu Yongkai, and Wang Haitao
The spectrum of amplifier spontaneous emission (ASE) is non-Gaussian, sidelobe appears inevitably and it will infect the measurement of molecular which is more or less the same as the coherence length seriously. In this paper, the denoising function of wavelet transform is used, and the coherence signal is processed wiThe spectrum of amplifier spontaneous emission (ASE) is non-Gaussian, sidelobe appears inevitably and it will infect the measurement of molecular which is more or less the same as the coherence length seriously. In this paper, the denoising function of wavelet transform is used, and the coherence signal is processed with Daubechies 10 making three layer wavelet decomposition, different frequency signals are denoising by different threshold values. It can not reduce the influence of sidelobe greatly, but remain most of the mainlobe signal. The result shows that wavelet transform is good for extracting the useful information. A particle specimen is used to simulate the measurement of molecular and the diameter is about 30 μm. The results of the experiments demonstrate this system has the advantage of high resolution..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 72 (2008)
Low-Rate and Scalable Image Coding with Sparse Representations
Sun Yubao, Xiao Liang, Wei Zhihui, and Hu Xiyuan
Based on geometric properties of the local image structures and the perception characters of human visual system (HVS), a geometrically motivated Gabor multi-component perception dictionary is constructed. Moreover, inspired from the hierarchical information processing in the human visual path, a sparse coding network Based on geometric properties of the local image structures and the perception characters of human visual system (HVS), a geometrically motivated Gabor multi-component perception dictionary is constructed. Moreover, inspired from the hierarchical information processing in the human visual path, a sparse coding network is proposed to reduce high order redundancy, thus provides much sparser representations of images. Furthermore, coefficients of repositioned atoms in sparse approximation are quantized by bit-plane quantization. It presents an effective low bit-rate and scalable image compression algorithm. Our simulation results show that, under the low bit-rate, our approach is comparable to the JPEG2000 in terms of PSNR value, while effectively preserves edges and textures structures and exhibits generally a better visual quality..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 77 (2008)
Propagation of Vortex Beams in a Turbulent Atmosphere
Wang Tao, Pu Jixiong, and Chen Ziyang
Based on the extended Huygens-Fresnel principle, the propagation of vortex beams in a turbulent atmosphere has been investigated. It is found that the beam profile will approach to a Gaussian shape when the vortex beam propagates a distance in a turbulent atmosphere, and the topological charge and the atmospheric turbuBased on the extended Huygens-Fresnel principle, the propagation of vortex beams in a turbulent atmosphere has been investigated. It is found that the beam profile will approach to a Gaussian shape when the vortex beam propagates a distance in a turbulent atmosphere, and the topological charge and the atmospheric turbulence will influence the changes of the intensity distribution. It is also found that vortex beams can reduce the beam-spreading induced by the atmospheric turbulence. Moreover, the topological charge of the vortex beam propagating in a turbulent atmosphere has also been studied by using the Young’s double-slit interference experiment. It is found that the topological charge of the beam will exhibit fluctuating as it propagates through a turbulent atmosphere..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 82 (2008)
Experimental verification of Phase Retrieval Based on Intensity Transport Equation
Wang Xiao, Mao Heng, and Zhao Dazun
The phase of optical wave can be recovered by the intensity transport equation (ITE) under the paraxial approximation For the optical system with diffraction limit, it is difficult to get the boundary radical slope of phase and sample in the circular domain boundary when using the intensity transport equation to recovThe phase of optical wave can be recovered by the intensity transport equation (ITE) under the paraxial approximation For the optical system with diffraction limit, it is difficult to get the boundary radical slope of phase and sample in the circular domain boundary when using the intensity transport equation to recover the phase, consequently, we reviewed an algorithm mentioned in the reference ［4］, namely, the equation, computation domain and boundary condition are changed, then the phase is reconstructed by the multigrid method and corrected at last Moreover, the experiment system is set to testify the algorithm, and the recovered phase from the intensity data detected by CCD is compared with the result from phase retrieval(PR) algorithm, it is found that the phase reconstruction error can reach 017 λ in the case of non-uniform intensity distribution, as a result, the method is suitable for the phase recovery with low wavefront sensing accuracy..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 87 (2008)
Simulation of Superfine Particles Dynamic Light Scattering Based on Auto-Regressive Module
Wang Yajing, Zheng Gang, Shen Jin, Tan Boxue, and Cheng Yanting
In order to simulate the dynamic light scattering signal of superfine particles, an auto-regressive (AR) model of the random process is made by analysing the character of dynamic light scattering signal. The module parameter is identified by Levison-Durbin algorithm and the method of selecting module order is given wheIn order to simulate the dynamic light scattering signal of superfine particles, an auto-regressive (AR) model of the random process is made by analysing the character of dynamic light scattering signal. The module parameter is identified by Levison-Durbin algorithm and the method of selecting module order is given when scattering signal of unimodal and bimodal distribution particles is simulated. Thus a simulative method of dynamic light scattering signal based on AR module is put forward. By this method, the scattered signal of 50 nm, 300 nm, 1000 nm and scattered signal of 50 nm and 1000 nm, 100 nm and 500 nm, 300 nm and 1000 nm were respectively simulated when the module order was 1, 1, 1, 57, 28, 40. Their simulative autocorrelation function of light intensity accords with their theoretical autocorrelation function. The unimodal distribution’s relative error of inverting particles size by cumulants and the bimodal distribution’s relative error of inverting particles size by double exponential were respectively less than 0.58%, 3.7%. The results show that the signal simulation of unimodal distribution particles need one order module, and the signal simulation of bimodal distribution particles with differernt sizes need differernt order module..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 91 (2008)
Data and Pixel Match in Holographic Disc Storage
Wang Ye, and Tao Shiquan
The holographic disc storage (HDS) technology has become one of the potential new types of optical storage technologies. In order to obtain precise input and output information, hence, reduce the bit-error rate in the retrieved data, the accurate pixel matching between the whole high-resolution page of SLM and CCD mustThe holographic disc storage (HDS) technology has become one of the potential new types of optical storage technologies. In order to obtain precise input and output information, hence, reduce the bit-error rate in the retrieved data, the accurate pixel matching between the whole high-resolution page of SLM and CCD must be ensured. We discuss the method and technique of pixel matching based on volume holographic storage theory, and then accomplished an optical system to realize pixel match by imaging a random data both mask and SLM of 512×512 pixels. The results showed that 1∶1 pixel matching between spatial light modulator (SLM) and CCD was realized, and a raw bit-error-rate (BER) of 1.5×10-4 (2.5×10-4 of mask) was achieved..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 95 (2008)
Bit Error Rate Performance Analysis of Atmospheric Optical Communication System Based on Gamma-Gamma Turbulence Channe
Wu Hanling, Li Xinyang, and Yan Haixing
In atmospheric channel, atmospheric turbulence is one of the main factors that degrade the performance of atmospheric optical communication systems. Turbulence-induced intensity scintillation often reduces the capability of receiver to extract and recover information contained in the modulated optical wave. Based on thIn atmospheric channel, atmospheric turbulence is one of the main factors that degrade the performance of atmospheric optical communication systems. Turbulence-induced intensity scintillation often reduces the capability of receiver to extract and recover information contained in the modulated optical wave. Based on the Gamma-Gamma distribution, the bit error rater (BER) performance of atmospheric optical communication system using subcarrier PSK intensity modulation is investigated. The bit error rate for turbulent channel is derived for subcarrier BPSK and OOK modulation schemes. Under some conditions, comparison is given about the BER performance of the above-mentioned two modulation schemes. The influences of link character, aperture diameter, wavelength and zenith angle on the BER are evaluated. Results show that the BER is effectively reduced by increasing aperture and wavelength and increases with increasing the zenith angle. It is also shown that the BER performance of systems employing subcarrier BPSK modulation is much better than that of compatible systems employing OOK modulation..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 99 (2008)
A Quality Scalable Coding Algorithm of Images Based on Non-Redundancy Contourlet
Xiao Liang, Hu Xiyuan, and Wei Zhihui
A novel quality scalable image coding scheme at low-medium based on non-redundancy contourlet transform is proposed. Using the bi-orthogonal wavelet decomposition and directional filter banks, the image non-redundancy sparse representation can be obtained, in which not only it is capable of efficiently characterizing tA novel quality scalable image coding scheme at low-medium based on non-redundancy contourlet transform is proposed. Using the bi-orthogonal wavelet decomposition and directional filter banks, the image non-redundancy sparse representation can be obtained, in which not only it is capable of efficiently characterizing the linear singularity and texture in images but also it can overcome the drawback of 4/3 redundancy in classical contourlet transform. According to the statistical distribution characteristic of coefficients of each subband of non-redundancy contourlet, an elaborated reposition algorithm for the transform coefficients is presented to construct the spatial-orientation tree. Furthermore, the “zero-tree” characteristic of this structure is statistically validated. Then under the principle of set partitioning in hierarchical tree-(SPIHT) algorithm and threshold quantization method, the quality scalable image coding procedure is obtained. Our experimental results demonstrate that at the low to medium rate, the decoding image of the proposed algorithm is competitive to the JPEG2000 in terms of PSNR value, but is visually superior to the wavelet based SPIHT or JPEG2000, especially for those regions with plentiful textures and edge..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 106 (2008)
A Novel Method for Roll Measurement Based on Grating
Zhai Yusheng, Feng Qibo, and Zhang Bin
A novel method for roll measurement is presented based on one-dimensional grating. The effects of straightness errors are avoided by using the measuring unit consisting of a focusing lens and photodetector. This method realizes errors separation, avoiding crosstalk of pitch angle and yaw angle, and enhances the abilityA novel method for roll measurement is presented based on one-dimensional grating. The effects of straightness errors are avoided by using the measuring unit consisting of a focusing lens and photodetector. This method realizes errors separation, avoiding crosstalk of pitch angle and yaw angle, and enhances the ability of anti-interference by adopting double optical paths differential measurement based on the ±1 order diffractive beams. Feasibility of the method is analyzed in detail. Calibration curve, whose linear dependency is 1, is obtained by experiment. The results show that resolution of the rolling error is less than 0.6″. The method is simple and flexible enough to meet the different accuracy demands just by choosing the different gratings..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 112 (2008)
Optical Image Encryption and Multiple Parameter Weighted Fractional Fourier Transform
Zhang Haiying, Ran Qiwen, and Zhang Jin
In order to increase the security of the image encryption, the weighted fractional Fourier transform with dilation parameter (PWFRFT) is proposed. This PWFRFT is an extension of four-item weighted fractional Fourier transform (FRFT) defined by C.C.Shih. It owns four free parameters, which is called the vector parameterIn order to increase the security of the image encryption, the weighted fractional Fourier transform with dilation parameter (PWFRFT) is proposed. This PWFRFT is an extension of four-item weighted fractional Fourier transform (FRFT) defined by C.C.Shih. It owns four free parameters, which is called the vector parameter here, in the weight coefficients besides the order of the fractional Fourier transform. A novel optical image encryption algorithm is presented by the PWFRFT. The method owns ten secret keys when two-dimensional PWFRFT is operated one time: one kind is the order parameter and other kind is the vector parameter. Therefore, the new encryption method makes the security of image information better and the encryption process simpler. Digital simulations are presented to verify the validity and efficiency of the algorithm..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 117 (2008)
Research on Display Panel Precise Positioning System Based on Computer VisionTechnology
Zhang Jinlong, Liu Yang, Pan Shili, Liu Jingnan, and Yoshihisa Uchida
In view of the features of display panel position of SMPDP, a precise positioning device was established using computer vision technology. This device based on industrial control computer can achieve high-accuracy position detection and full automatic precision plane alignment using CCD signals , so that it could achieIn view of the features of display panel position of SMPDP, a precise positioning device was established using computer vision technology. This device based on industrial control computer can achieve high-accuracy position detection and full automatic precision plane alignment using CCD signals , so that it could achieve automatic precision positioning of front substratum, shadow mask and rear substratum. The algorithms such as fast image edge detection, character extraction and positioning control strategy are proposed to reduce the time of image processing and improve the detection accuracy. A series of anti-interference step in the hardware and software of the device effectively improve positioning accuracy and reliability of the device. The experimental result shows the device can perform positioning accuracy of ±5μm. The approaches are of high value for accelerating the industrialization ofSMPDP..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 121 (2008)
Analytical Solutions for Gaussian Beam Propagation Beyond the Paraxial Approximation
Zhang Xiaping
Starting from the vector potential and the scalar potential in the Lorentz gauge, the nonparaxial beam propagation is studied in free space. Applying Fourier transform and angular spectrum, the equation has been derived for transverse electric fields of an arbitrary polarized electromagnetic wave with the new approximaStarting from the vector potential and the scalar potential in the Lorentz gauge, the nonparaxial beam propagation is studied in free space. Applying Fourier transform and angular spectrum, the equation has been derived for transverse electric fields of an arbitrary polarized electromagnetic wave with the new approximation and multiscale perturbative method, the analytical solution for Gaussian beam propagation beyond the paraxial approximation is accessed. For weakly nonparaxial beams that are characterized by small values of the perturbative parameter, our corrective solictions yield an accurate description of the field in the near-field regin. We firstly give the eighth correction solution, our correction, solutions yield an accurate description of the field in the near-field region. In addition, the lowest-order correction to the paraxial approximation can be found to be the Gaussian..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 125 (2008)
Time-Frequency Analysis of Stacking Chirped Optical Pulses Based on Wavelet Tranform
Zhang Zhiyao, Zhou Xiaojun, Sui Zhan, Wang Jianjun, and Li Mingzhong
We deduced the analytical expression of the time-resolved energy spectrum density for shaped pulse stacked by 2M chirped Gaussian pulse using wavelet transform and complex Morlet function. Time-resolved power and instantaneous central wavelength distribution of the stacking chirped Gaussian pulse have been obtained thrWe deduced the analytical expression of the time-resolved energy spectrum density for shaped pulse stacked by 2M chirped Gaussian pulse using wavelet transform and complex Morlet function. Time-resolved power and instantaneous central wavelength distribution of the stacking chirped Gaussian pulse have been obtained through wavelet transform. It’s found that the power oscillates in the time domain, and the instantaneous central wavelength jumps when the power is zero. Increasing the chirp will aggravate the power oscillation and the instantaneous central wavelength jump. The instantaneous central wavelength jump occurs only when the power is zero. Therefore, the pulse energy remains in the wavelength range determined by the chirp of fundamental pulse. Simulating results also show that a little change of the pulse overlap factor will greatly influence the packing ratio and the flatness of the shaped pulse, both of those cannot simultaneously reach optimum. Therefore, the pulse overlap factor should be selected eclectically..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 129 (2008)
Simulation Method of Receiving Signal in Satellite-Ground Laser Communication
Zhu Yong, and Sun Xiaoxia
In satellite-ground laser communication system, atmospheric turbulence causes the fluctuation of the receiving optical signal, which can arouse burst bit error while in bad situation In order to study the characteristic and influence of the burst bit error, a new simulation method of fluctuated receiving signal simulaIn satellite-ground laser communication system, atmospheric turbulence causes the fluctuation of the receiving optical signal, which can arouse burst bit error while in bad situation In order to study the characteristic and influence of the burst bit error, a new simulation method of fluctuated receiving signal simulation was studied in this paper, which uses the power series of Gaussian process to fit the target process The highest power order of Gaussian process was set to 3, and the factor of power series was obtained from the statistic character (mean, quadratic mean deviation, skewness and kurtosis) of the envelope fluctuation of the receiving optical signal, and the power spectra density of the fluctuation was fit by FFT /IFFT. This method takes advantages in computational complexity and resource consumption..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 134 (2008)
Identification of Liquor Using Fluorescence Spectra
Chen Guoqing, Zhu Tuo, Wu Yamin, Yang Jianlei, and Wu Hao
On the basis of study about fluorescence spectra of alcohol-water mixtures and their characteristic, by using SP-2558 multifunctional spectral measuring system, the fluorescence spectra of more than 50 kinds of liquors excited by ultraviolet (UV) light have been measured. The results show that a stronger fluorescence cOn the basis of study about fluorescence spectra of alcohol-water mixtures and their characteristic, by using SP-2558 multifunctional spectral measuring system, the fluorescence spectra of more than 50 kinds of liquors excited by ultraviolet (UV) light have been measured. The results show that a stronger fluorescence can be generated when liquor is excited by UV light, and its characteristic is clear. Three-dimensional fluorescence spectra of various liquor were measured. Based on this, a fluorescence spectra fingerprint atlas of liquors was constructed. Through analysis, a spectra database of liquors including the number of peaks, the peak wavelength, best exciting wavelength, etc. was established. By using SGL Server 2005 and VB 6.0, an intelligent identification system of liquors was created. The fluorescence spectra of unknown liquor can be automatically compared with those of known liquor in the database, and this system can intelligently identify liquor and get degree of similarity. Fluorimetry has high sensitivity and accuracy, its sample is a little and need not pre-treatment, this work bring the advantages of fluorescence spectroscopy into play, the research results provide an effective new method for identification of liquors, it can be applied to production management and market supervision of liquor, and provide helps for food safety..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 139 (2008)
Crushing Cells under Low-Voltage and Its Optical Testing Method
Chen Jianjun, Liao Honghua, Wang Jun, Han Heyou, and Yu Jun
It is intended to obtain the cell contents (protein, DNA, RNA etc.) and probe into the application of optoelectronic technology for crushing cell. In theory BHK21 initial transmembrane voltage is introduced to modify the voltage model. Control and detecting systems for crushing cells are made as follows: crushing cellsIt is intended to obtain the cell contents (protein, DNA, RNA etc.) and probe into the application of optoelectronic technology for crushing cell. In theory BHK21 initial transmembrane voltage is introduced to modify the voltage model. Control and detecting systems for crushing cells are made as follows: crushing cells chip electrodes 50 μm in both width and pitch interval, with a length of 0.4 cm and thickness of 0.5 μm each. The system could be used in cells crushing, controlling and automatic testing. It takes inverted microscope as the main light path system, collects pictures with 3 mega pixel CCD camera and deals them with processing software of micro-digital image. The experiment shows that this optical testing system could automatically identify and count BHK21 in micro-windows. For crushing BHK21 cells, the most suitable voltage range and pulse width are 3 V and 3 ms..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 143 (2008)
Design and PIC Simulation of 3 mm Band Gyroklystron Amplifier
Huang Yong, and Li Hongfu
A 3 mm band four cavity gyroklystron was designed and simulated. The working mode was the low loss TE01 mode. Linear theory was applied to determine the initial operating parameters. The famous FEM code HFSS was used to optimization design of every single cavity. PIC simulation code was used to design the interaction cA 3 mm band four cavity gyroklystron was designed and simulated. The working mode was the low loss TE01 mode. Linear theory was applied to determine the initial operating parameters. The famous FEM code HFSS was used to optimization design of every single cavity. PIC simulation code was used to design the interaction circuit. Studies to determine the optimal stagger tuning and cavity Q values were performed. Circuit stability was investigated and the effect of beam parameter variation on circuit performance was also studied. Simulations show that a four cavity circuit operating in the TE01 mode at the fundamental of the cyclotron frequency can achieve 139 kW peak output power, 35.6% efficiency and 28.4 dB gain at a center frequency of 93.7 GHz with about 600 MHz full width half maximum (FWHM) bandwidth for a 65 kV, 6 A, pitch angle α(V⊥/V∥)1.5 and velocity spread 0% beam..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 146 (2008)
Automatic Test of Sphericity for Micro Glass Bead
Jiang Shuhua, Ren Yanjun, and Wang Wensheng
Modern optical test technique, computer technique and photoelectric technique are combined. A test system with the CCD matrix, imaging objective and computer is researched to realize 2-D high accuracy, non-contact, real time and automatic measurement. The system has a simple structure and can be easily operated withoutModern optical test technique, computer technique and photoelectric technique are combined. A test system with the CCD matrix, imaging objective and computer is researched to realize 2-D high accuracy, non-contact, real time and automatic measurement. The system has a simple structure and can be easily operated without the strict requests for environment. We need to obtain the edge contour parameter of the measured workpiece in order to achieve non-contact and automatic measurement. The testing device solves the key technologies of non-linearity smooth, the threshold value selection and edge abstraction. Because the system uses the method of the edge contour track to obtain the edge contour image of workpiece, the edge contour curve of workpiece can be precisely determined. Sphericity of micro glass bead is tested as an example. The testing system adopts non-contact test and overcomes some inherent disadvantages of the traditional testing method. The system will not cause permanent damage to the workpiece. The experiments show that the testing range is large, the absolute accuracy is less than 3 μm with good repeatability..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 149 (2008)
Application of Micrograph Measuring System on Body Tissue′s Typical Parameters
Wei Benzheng, Zhao Zhimin, and Li Hongjun
The obtaining of body tissue′s typical parameter is very important to the diagnoses and curing of diseases. In this thesis we designed a micrograph measuring system with high performance to measure the typical parameters of body tissue. A series of key techniques involved such as the principle of the system, image grabThe obtaining of body tissue′s typical parameter is very important to the diagnoses and curing of diseases. In this thesis we designed a micrograph measuring system with high performance to measure the typical parameters of body tissue. A series of key techniques involved such as the principle of the system, image grabbing system, image creating system, and the image processing software, are explained. Having a high degree of intelligence, the system can measure and analyze the imaging observation fast and effectively, and the digital parameter also can be acquired automatically. The experimental results show that this system can observe the micrograph of body tissue, calculate and save the morphological parameters of micro-blood vessel network and kinetic parameters of micro-blood stream simply and accurately. So this system can be used as an important tool in the medical research area..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 153 (2008)
OPTOELECTRONICS
Optimum Design and Analysis of Vane in Satellite Remote Sensor
Du Baolin, Li Lin, Huang Yifan, Jiang Zhenyu, and Zhao Yuanyuan
Space optical systems always work in very bad conditions. The sunlight, airlight and various radiation, coming from the space constitute serious background noise of image plane in space optical system. This noise can reduce imaging quality, and even leads to detectivity losing of satellite remote sensor because of unabSpace optical systems always work in very bad conditions. The sunlight, airlight and various radiation, coming from the space constitute serious background noise of image plane in space optical system. This noise can reduce imaging quality, and even leads to detectivity losing of satellite remote sensor because of unable imaging. Because it can improve the bad influence coming from background noise and prevent directly stray-light out of the field of view, the vane has the ability to raise the ability of suppressing stray light. However, diffraction effect will occur when rays arrive the edge of vanes due to the small size of vanes. So, how to design reasonable vane is very important in baffle designing. A new type of vane which is produced by using focus-assemble innovation method is proposed in this article. Having compared with existing vanes and simulated, this new type of vane is proved to be predominant in stray light suppressing..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 233 (2008)
Infrared Gas Sensor Based on Fresnel Lens Array
Du Xiaoqing, and Xu Can
Fresnel lens can realize both focus and dispersion of light and it also has the virtues including small volume, light weight and reproducibility, which makes it be widely used in spectral inspection. Typical spectral imaging instrument with Fresnel lens obtains continuous spectral lines by moving Fresnel lens along optFresnel lens can realize both focus and dispersion of light and it also has the virtues including small volume, light weight and reproducibility, which makes it be widely used in spectral inspection. Typical spectral imaging instrument with Fresnel lens obtains continuous spectral lines by moving Fresnel lens along optical axis and therefore it will greatly decrease the stability of the whole instrument. Considering the requirement of gas detection, multi-channel mode was adopted to obtain multi-spectral and a novel infrared gas sensor based on a Fresnel lens array was presented. The gas sensor can real-time check and inspect of CO2, CO, CH4 and SO2 gases, whose adsorption wavelengths are all within from 3 μm to 5 μm infrared waveband. The relationship of spectrum resolution of Fresnel lens with structure parameters of lens was deduced by use of transmission theory of spherical wave and Rayleigh criterion. Moreover, structure parameters and their fabrication errors for 1 μm fabricated and eight phased Fresnel lens array were calculated when spectral resolution is required to be less than 50 nm. The calculated results show that the focal length of lens array is required to be 47.84 mm and the average numerical aperture can be more than 0.4..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 237 (2008)
Study on Fabricating Polymer Segmented Cladding Fiber by Bicomponent Spinning
Duan Julan, Teng Cuiqing, Han Keqing, and Yu Muhuo
A segmented-cladding fiber (SCF), which consists of a uniform core of high refractive index and a cladding with regions of high and low refractive index alternating angularly, provides an effective approach for achieving widely extended single-mode operation with a large core size. Fabricating segmented cladding fiber A segmented-cladding fiber (SCF), which consists of a uniform core of high refractive index and a cladding with regions of high and low refractive index alternating angularly, provides an effective approach for achieving widely extended single-mode operation with a large core size. Fabricating segmented cladding fiber by bicomponent spinning method was proposed. The polymer segmented cladding fiber with required cross section was successfully fabricated using polycarbonate (PC) and polymethyl methacrylate (PMMA). The core of obtained fiber is 40 μm in diameter. The output spectrum of obtained fiber was investigated using white light as the light source. From the output spectra, it was seen that the intensity in the wavelength of 730～830 nm is comparatively higher in the test range of 500～1000 nm. The transmission loss in the wavelength of 500～1000 nm was tested by the cut-back method. The result showed that the transmission loss of the obtained fiber is comparatively high, being up to 30 dB/m. The output light pattern of the obtained fiber of 60 cm was collected by a CCD camera with laser light of 532 nm as the input..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 241 (2008)
Embedded Three-Dimensional Imaging System
Guan Yingjian, Peng Xiang, Bruce Z. Gao, and Tian Jingdong
An embedded three-dimensional (3D) imaging system based on digital signal processor (DSP) is presented. The hardware platform of this prototype is composed of fringe projection, data acquisition, automatic fringe analysis as well as other supporting circuits and memories. The fringe projection module encoded the fringeAn embedded three-dimensional (3D) imaging system based on digital signal processor (DSP) is presented. The hardware platform of this prototype is composed of fringe projection, data acquisition, automatic fringe analysis as well as other supporting circuits and memories. The fringe projection module encoded the fringe patterns that is realized by the DSP software, and projected it on object surface through the digital light projection (DLP) to create structural light illumination. The deformed fringe patterns reflected from object surface is detected by a CCD camera and then acquired by data acquisition module that decodes the video signal. The module of automatic fringe analysis is utilized to demodulate the phase distributions of deformed fringe patterns with phase shifting technique, and followed by a phase unwrapping procedure to create continuous phase maps that correlate the height variation of object surface. Three major modules are controlled by the multi-thread technique to accomplish multi-tasks in a parallel fashion. The phase demodulation algorithm, the most time-consuming calculation, is optimized by the software pipeline combined with other strategies such as loop unfolding, data prefetching and inline functions, etc. Experimental results show that the proposed approach can implement the 3D shape measurement with fast speed and good accuracy. The optimized speed of phase unwrapping program is 7 times faster than it before..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 244 (2008)
A Dual-probe Three-Dimensional Profile Measurement System
Guo Li, Zhou Yage, Zhang Dongxian, and Zhang Haijun
A new three-dimensional (3D) profile measuring method which combines the atomic force microscopic (AFM) probe with the position sensitive detector (PSD) range probe is proposed. This method can obtain both the large size 3D profile and micro morphological character of a point on the sample. A dual-probe 3D profile measA new three-dimensional (3D) profile measuring method which combines the atomic force microscopic (AFM) probe with the position sensitive detector (PSD) range probe is proposed. This method can obtain both the large size 3D profile and micro morphological character of a point on the sample. A dual-probe 3D profile measuring system is developed. The working principle is elaborated and the three parts of the system, the dual-probe, the step-controlled scanning stage and the computer controlling center are illuminated. The measuring range of the system is demarcated by measuring a known grating of 2000 line/mm. The 3D surface profile images in local morphology and entire profile of an annular gasket with inside and external diameter of 4 mm and 8 mm are given respectively. The experimental results show that this system is expected to be utilized both in large range measurement and local three-dimensional reconstruction with high-precision for samples which are of different sizes and materials..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 249 (2008)
Data Segments Aggregation Performance in Next Generation Avionics Systems
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
We integrate the advantages of optical packet switching (OPS) network and fibre channel (FC) technology, and put forward fibre channel transportation based on optical packet switching network (FC over OPS) as a solution for next generation avionics systems internetworking. We focus our research work on the interrelatioWe integrate the advantages of optical packet switching (OPS) network and fibre channel (FC) technology, and put forward fibre channel transportation based on optical packet switching network (FC over OPS) as a solution for next generation avionics systems internetworking. We focus our research work on the interrelation between data segments aggregation and network real-timing performance. By simulation, we analyze the impact that bandwidth, minimum efficiency threshold and timing contribute to the network real-timing. Furthermore, we complete hardware prototype design and simulation, compare the results between software and hardware simulation and analyze the performance of this algorithm..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 253 (2008)
Application of Removing Cloud in Gray Remote Sensing Images with Wavelet Analysis
Jiang Xingfang, Dai Lili, Shen Weimin, and Tao Chunkan
Because of cloud in remote sensing images, the images were fuzzy and the information of earth objects could not been read. A new method for removing cloud had been projected based on wavelet analysis. The 1～8 orders decomposition for several gray remote sensing images 256 pixel×256 pixel was implemented with wavelBecause of cloud in remote sensing images, the images were fuzzy and the information of earth objects could not been read. A new method for removing cloud had been projected based on wavelet analysis. The 1～8 orders decomposition for several gray remote sensing images 256 pixel×256 pixel was implemented with wavelet analysis and the detail coefficients were multiplied with 1～10 times in the process of reconstruction. Firstly, the order 7 of decomposition and the times of detail coefficiency had been selected by maxium entropy with selected wavelet function. Secondly, the functions of bi-orthogonal 2.2 wavelet and discrete approximation of Mery wavelet had been found by maxium entropy with selected order number and times. Finally, the exact order number and times had been shown in the curves of 1～8 orders decomposition and the times from 1 to 10 with 0.1 step length. The results show that the times 1.1 was best times for removing cloud from remote sensing images with thin cloud, and for discrete approximation of Mery wavelet there were two peaks in the times as 4.8 and 5.7..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 258 (2008)
Analysis and Application of Ultra-High Dynamic CCD Characters for Camera
Kang Juan, Feng Aiming, Xu Shiqing, and Li Chenxia
The principles traditional CCD and supper CCD were compared "S-pixel" with large area and high light, "R-pixels" with small area for expanding the dynamic range constitute supper CCD. Based on Fujifilm F100fd with super CCD for signal acquisition devices, we captured the hole diffraction image, all The principles traditional CCD and supper CCD were compared "S-pixel" with large area and high light, "R-pixels" with small area for expanding the dynamic range constitute supper CCD. Based on Fujifilm F100fd with super CCD for signal acquisition devices, we captured the hole diffraction image, all which can reduce the number of noises and make the finally image keeping normal under dark environment with non-overflow under high-brightness. Compared with ordinary CCD, super CCD can expand the dynamic range to about four times, optical diffraction image were detected to verify the feasibility and correctness of the paper..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 262 (2008)
Experimental Study of Micromachined Membrane Deformable Mirror Adaptive Optical System
Li Bangming, Liao Wenhe, Tong Gui, and Liang Chun
In order to obtain the optimal control voltages of adaptive optics system, an closed-loop iterative control algorithm based on improved singular value decomposition is proposed. By adjusting parameters g1, g2 and w, the convergent velocity of model can be optimized, and the control signal can converge a reliable local In order to obtain the optimal control voltages of adaptive optics system, an closed-loop iterative control algorithm based on improved singular value decomposition is proposed. By adjusting parameters g1, g2 and w, the convergent velocity of model can be optimized, and the control signal can converge a reliable local optimal solution rapidly. An adaptive optical system based on micromachined membrane deformable mirror(MMDM) which optical influence functions of every actuator are measured is built. The quasi-square relationship between voltage and displacement of an actuator and the quasi-linear superposing among the actuators are experimentally verified. Wavefront from a model eye and a human eye are used respectively as the incident wavefront of adaptive optics system. Experimental results show that the improved algorithm can correct static and dynamic distorted wavefront aberration rapidly and effectively, is very suitable for adaptive optical system based on MMDM..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 266 (2008)
Evaluation of Uncertainty for CO Monitor Based on Tunable Diode Laser Absorption Spectroscopy
Li Honglian, Li Xiaoting, Li Jinhai, Han Bing, and Dong Fang
The concentration of CO is measured by tunable diode laser absorption spectroscopy (TDLAS) technology. The experimental data of measurement signals are inversely processed by applying the overall second harmonic least squares data processing algorithm. The principal sources of measurement results uncertainty are analyzThe concentration of CO is measured by tunable diode laser absorption spectroscopy (TDLAS) technology. The experimental data of measurement signals are inversely processed by applying the overall second harmonic least squares data processing algorithm. The principal sources of measurement results uncertainty are analyzed during measurement of CO concentration by TDLAS. The uncertainty components, standard uncertainty, and synthesis uncertainty caused by various factors are evaluated with the direct evaluation method. The results indicate that the major factors affecting measurement uncertainty are the uncertainty of the apparatus, concentration definite value uncertainty of calibration gas, and the uncertainty indicated by ambient temperature variation and supply voltage fluctuation..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 271 (2008)
A Preliminary Study on THz Imaging and Image Enhancement Based on Thermal Imager
Li Qi, Yao Rui, Shan Jixin, Yin Qiguo, and Wang Qi
THz array imaging system is constructed by utilizing the thermal imager of Pyrocam III made in USA and laser of SIFIR-50. Imaging experiments on 20 paper money with 2.52 THz laser are done in order to explore array imaging mechanism and method of imaging enhancement. The effects of the methods of contrast stretching trTHz array imaging system is constructed by utilizing the thermal imager of Pyrocam III made in USA and laser of SIFIR-50. Imaging experiments on 20 paper money with 2.52 THz laser are done in order to explore array imaging mechanism and method of imaging enhancement. The effects of the methods of contrast stretching transformation, histogram equalization, and median filter are studied according to the THz array image added by 5 images. The experimental results show that employing this imaging system and subsequent image processing, the images obtained are similar with the objects. For the low contrast images, the effects are not obvious only by contrast stretching transformation. Good effects are gained with the method of histogram equalization, and the effects of image enhancement are better when employing mean filtering after histogram equalization..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 275 (2008)
Application of Coherent Optical Detection Technology Based on Acousto-optic Deflecting Effect
Liao Xin, He Ning, Chen Ming, and Chen Mingsong
To adapt modern electronic reconnaissance techniques to the electromagnetic environment of dense signal, broadband spectrum, and large dynamic range, a coherent optical signal processing method based on acousto-optic deflector is presented. The relationship between the changes of radio-frequency signal frequency and BrTo adapt modern electronic reconnaissance techniques to the electromagnetic environment of dense signal, broadband spectrum, and large dynamic range, a coherent optical signal processing method based on acousto-optic deflector is presented. The relationship between the changes of radio-frequency signal frequency and Bragg diffraction angle is analyzed, spatial filtering characteristic resulted from acousto-optic deflection effects is discussed. On the basis of theoretical analysis, the experimental system using acousto-optic technique is established to achieve coherent optical signal detection in the visible light range. The feasibility of this method is proved by computer simulation results. Experimental results show that if the system uses a single-frequency laser with wavelength of 630 nm and a acousto-optic deflector with bandwidth of 200 MHz, the frequency resolution is better than 1 MHz, the space separation effect of frequency signal is obvious, and the received sensitivity and signal-to-noise ratio (SNR) are improved..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 278 (2008)
Software-Synchronized Optical Sampling Based on PPLN Waveguide
Liu Maotong, Yang Aiying, and Sun Yunan
With the emergence of high speed optical communication system above 40 Gb/s, to ensure the quality of the transmitted optical signal, the optical signal in the transmission line should be monitored. The optical sampling technique is an important tool to perform time-resolved measurements of optical data signals at highWith the emergence of high speed optical communication system above 40 Gb/s, to ensure the quality of the transmitted optical signal, the optical signal in the transmission line should be monitored. The optical sampling technique is an important tool to perform time-resolved measurements of optical data signals at high bit rates with a bandwidth that cannot be reached by conventional photodetectors and oscilloscopes. The method with a fixed offset frequency can be used to sample the high speed optical signals with the sampling pulses of several hundred MHz. It relaxes the requirements of the bandwidth of electrical data processing system after the sampling. Based on the modeling and simulation of optical sampling process utilizing the sum-frequency generation in periodically poled lithium niobate (PPLN), the optical sampling of 10 Gb/s nonreture-to-zero (NRZ) and retrun-to-zero (RZ) signals in the transmission line obtained by Optsim is realized. The sampling results are processed by software-synchronized algorithm and the eye diagram of the signals is constructed. This method requires the least amount of hardware components. Compared with the sampling results of ideal AND gate, the sampling characteristics of PPLN waveguide and the quality of the sampling are analyzed by the obtained eye diagrams..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 283 (2008)
Fitting of Light Autocorrelation Function Based on Unconstrained Nonlinear Optimization Algorithm
Liu Wei, Shen Jin, Chen Wengang, and Tan Boxue
The nonlinear cumulants analysis is an important method in photon correlation spectroscopy (PCS) particle sizing technique. Using unconstrained nonlinear optimization algorithm, optimum fitting result is achieved in the nonlinear fitting process with random original value, and the implementation of the algorithm is preThe nonlinear cumulants analysis is an important method in photon correlation spectroscopy (PCS) particle sizing technique. Using unconstrained nonlinear optimization algorithm, optimum fitting result is achieved in the nonlinear fitting process with random original value, and the implementation of the algorithm is presented. Autocorrelation functions of scattered light signal of normal polystyrene latex particles of 50 nm, 100 nm, 200 nm and 500 nm are fitted using this method, and particle sizes are inversed. Comparied with other curve fitting algorithm, this method has little dependence on original value, and the inversed particle sizes are more close to the nominal value with less measurement error..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 289 (2008)
Study of Interferometric Synthetic Aperture Radar Data Processing Method Based on Three Part Images
Yu Qifeng, Long Xuejun, Fu Sihua, and Yang Xia
The single look complex image of synthetic aperture radar interferometry (InSAR) data includes four parts, all the parts of which will be used with the current InSAR data processing methods, which, however, is loaded with high-level decorrelation noise. In this paper, the InSAR data processing method proposed by the auThe single look complex image of synthetic aperture radar interferometry (InSAR) data includes four parts, all the parts of which will be used with the current InSAR data processing methods, which, however, is loaded with high-level decorrelation noise. In this paper, the InSAR data processing method proposed by the authors based on three part images are introduced comprehensively. The new technology includes image pair registration and the creation of interferograms. which is named contoured correlation interferometry (CCI). Firstly, the algorithm for the calculating of fringe orientations is introduced and improved. Secondly, the formulations of the image pair registration and the creation of interferograms are deduced with the correlation method in this paper, Simulative and practical experiments indicate that CCI method which needs only arbitrary three image parts from the four image parts of InSAR complex image pair to get interferogram without noise and blurring effect is a totally novel method to InSAR data processing, which also can save the time to data transferring and processing..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 292 (2008)
Super-Resolution Digital Holography by Beam Scanning
Pan Weiqing, Zhu Yongjian, Lu Wei, Wang Jianzhong, and Hu Wei
Based on super-resolution imaging theory, a beam scanning super-resolution digital holographic technique is proposed. Applying Fresnel diffraction theory, this technique is proved to enlarge the equivalent dimension of CCD and increase the cutoff frequency of optical system, so this method can improve the imaging resolBased on super-resolution imaging theory, a beam scanning super-resolution digital holographic technique is proposed. Applying Fresnel diffraction theory, this technique is proved to enlarge the equivalent dimension of CCD and increase the cutoff frequency of optical system, so this method can improve the imaging resolution of digital holography. The simulation verify the validity and feasibility of this method. The method of hologram processing and reconstruction is summarized. Compared with synthetic-aperture digital holography, the proposed technique needs not to move CCD camera and change the angle of reference waves that correspond to different CCD camera position for avoiding under-sampling..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 299 (2008)
Signal Detection of Laser Radar Based on the Background Character Parameter
Ping Qingwei
The detection of the faint target in the lidar is one of the key technologies of the lidar. One of its difficulties is that the characteristic distinguishing the target and the noise is very lacking. The target this paper researches is the plane. After researching the practical echo signal, we find that the target ofteThe detection of the faint target in the lidar is one of the key technologies of the lidar. One of its difficulties is that the characteristic distinguishing the target and the noise is very lacking. The target this paper researches is the plane. After researching the practical echo signal, we find that the target often is the isolated dot in the echo signal. The target is irrelevant with the noise. However, the noise is expressed with the neighboring dot. To resolve the problem of the target detection in low signal-to-noise, an algorithm of the target detection based on the background characteristic parameter is presented. The clutter is processed using the background characteristic parameter of mean variance. In the small region, the mean variance of the background is steady. However, the mean variance of the target is distinct. Therefore, the signal-to-noise is improved greatly. Then with CFAR detection and multi-frame relative detection, the true target is captured. The experimentation had proved this algorithm improved the performance of the lidar. This algorithm is effective and does well on real time, it is valuable in practice..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 304 (2008)
Digital Watermarking Based on Kinoform and Wavelet Transform
Qi Yongkun, Peng Xiang, Guan Yingjian, Bruce Z. Gao, Meng Xiangfeng, and Qin Wan
A novel digital watermarking scheme based on the kinoform and discrete wavelet transform (DWT) is proposed. The watermark image to be hidden is first encoded into a kinoform by utilizing the iterative phase retrieval algorithm in a virtual lens system. The weighted kinoform is embedded into the low-frequency DWT coeffiA novel digital watermarking scheme based on the kinoform and discrete wavelet transform (DWT) is proposed. The watermark image to be hidden is first encoded into a kinoform by utilizing the iterative phase retrieval algorithm in a virtual lens system. The weighted kinoform is embedded into the low-frequency DWT coefficients (LL3) of the host image to accomplish the watermark embedding process. In the process of watermark extraction, the embedded kinoform can be extracted by subtracting the corresponding DWT coefficients of the host image, from that of the watermarked image. Then, the original hidden image can be retrieved by taking the real amplitude of Fourier transform (FT) information for the extracted kinoform. The robustness and imperceptibility of watermarked image with the different weighting factors are demonstrated and analyzed in detail. The feasibility of proposed approach have been verified by computer simulations..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 308 (2008)
Measurement of Electron Density in Plasma at Atmospheric Pressure by Spectroscopy
Ran Junxia, Zhang Shaopeng, Li Xia, Li Honglian, and Dong Lifang
The electron density of dielectric barrier discharge in micro-discharge at atmospheric pressure argon is measured by emission spectral method. Considering various broadening mechanisms of plasma, the unsymmetrical convolution procedure is compiled to fit the experimental spectral line profile, and the Stark broadening The electron density of dielectric barrier discharge in micro-discharge at atmospheric pressure argon is measured by emission spectral method. Considering various broadening mechanisms of plasma, the unsymmetrical convolution procedure is compiled to fit the experimental spectral line profile, and the Stark broadening profile can be obtained by deconvolution procedure to measure the electron density of plasma. The results show that the electron density in three filamentary micro-discharge at atmospheric pressure argon is 4.06×1021 m-3 if the electron temperature is 10000 K. The diagnosis result is in good agreement with the simulation. The method for measurement of electron density can be used not only in dielectric barrier discharge at atmospheric pressure, but also in other types of non-hydrogen plasma at atmospheric pressure..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 314 (2008)
Research on Evaluation Method of CCD Image Sensor
Shang Yuanyuan, Guan Yong, Zhang Weigong, and Zhao Xiaoxu
CCD image sensor plays an important role as major solid-state array in scientific imaging application for its excellent performance. Generally speaking, some important parameters of CCD imager, such as transfer efficiency, readout noise and so on, should be firstly measured to estimate whether the imager can satisfy thCCD image sensor plays an important role as major solid-state array in scientific imaging application for its excellent performance. Generally speaking, some important parameters of CCD imager, such as transfer efficiency, readout noise and so on, should be firstly measured to estimate whether the imager can satisfy the performance requirements of whole system, especially in the scientific application. So it is very important to make research on the evaluation method of CCD imager. The paper introduces evaluation method of some important CCD parameter, including gain, readout noise, charge transfer efficiency, linearity, and well capacity. The methods to measure charge transfer efficiency by Fe55 X-ray source and extended pixel edge reaction are mainly discussed. Several ways to evaluate CCD gain are also analyzed in detail. A platform to evaluate CCD imager in the laboratory is developed and measurement tests of E2V CCD203_82 are also carried out using this method. The experiments show that the evaluation method we developed is feasible, flexible, and reliable..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 317 (2008)
Study on Convergence of the Volterra Series Transfer Function Model of Optical Pulse′s Propagation in Fiber
Shao Qunfeng, Qi Xiaoqiong, and Zhang Xiaoping
The expression to represent the convergence of Volterra series transfer function (VSTF) was obtained based on the series convergence theory. The relationship of the pulse′s maximum input power to guarantee the convergence of VSTF, transmission length, and the order of VSTF can be explained by the expression mentioned aThe expression to represent the convergence of Volterra series transfer function (VSTF) was obtained based on the series convergence theory. The relationship of the pulse′s maximum input power to guarantee the convergence of VSTF, transmission length, and the order of VSTF can be explained by the expression mentioned above. The variation of pulse′s maximum input power to guarantee the convergence of VSTF versus transmission length when using different order VSTF to approximate in the given fiber′s parameters of the circumstances was derived from the numerical simulation applied to the expression. The results shows that the pulse′s maximum input power to guarantee the convergence of VSTF is not only related to the order of VSTF applied but also the pulse′s width and fiber′s dispersion parameter..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 323 (2008)
Jones Matrix Model of Birefringent Fibre in Magnetic Field
Bai Ye, Shi Zhidong, Liu Shu, Li Mingjia, and Chen Hua
Through the model of cascading retarder and rotator, the polarization transmission characteristics of birefringent fiber in magnetic field have been studied. By multiplying their Jones Matrixes in different cascading order, we have deduced the analytic expressions for the phase shift and fast axis orientation of the eqThrough the model of cascading retarder and rotator, the polarization transmission characteristics of birefringent fiber in magnetic field have been studied. By multiplying their Jones Matrixes in different cascading order, we have deduced the analytic expressions for the phase shift and fast axis orientation of the equivalent retarder as well as the angular rotation of the equivalent rotator. When linear birefringence and circular birefringence occur in the same fiber, it is found that the equivalent phase retardation in unit length is not equal to its inherent birefringence, nor the equivalent angular rotation is equal to its Faraday rotation. They are relevant meanwhile both to the inherent linear birefringence of fiber and to the circular birefringence caused by the magnetic field. What’s more, in the equivalent models with different cascading order, the fast axis of the equivalent retarder does not coincide with the linear birefringent axis of fiber, but has an offset angle respectively with opposite spin-wise, and the offset is just equal to the half of the equivalent angular rotation..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 327 (2008)
A Signal Demodulating Algorithm for Extrinsic Fabry-Pérot Interferometer Sensor
Song Shide, Wang Xiaona, Yu Qingxu, and Xu Shilang
A new precision demodulation algorithm based on mean square error(MSE, estimation is reported. In parametric statistics, MSE combines the errors the variance of the estimator and its bias, so the MSE incorporating both precision and accuracy is a perfectly reasonable way to assess the quality of an estimator. If there A new precision demodulation algorithm based on mean square error(MSE, estimation is reported. In parametric statistics, MSE combines the errors the variance of the estimator and its bias, so the MSE incorporating both precision and accuracy is a perfectly reasonable way to assess the quality of an estimator. If there are numbers of estimators for a given true value, the estimator that leads to the smallest MSE is more efficient than the others. The actual air gap of the EFPI sensor is the air gap estimator whose MSE is minimum. The demodulation algorithm is evaluated with a pressure experiment, which shows an air gap resolution of 0.18 nm over the dynamic range of 1.84 μm, corresponding to a pressure resolution of 2.99 kPa over the applied pressure span of 31 MPa. Compared with traditional demodulation algorithms, both high-resolution and absolute air gap measurement can be achieved over a large dynamic range..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 332 (2008)
Linearity Analysis of Fiber-Optic Temperature Sensor Based on Semiconductor Optical Absorption
Sun Xuan, Li Min, Zhou Cong, and Li Yulin
A good linearity of measuring curve can improve the resolution of valid measure-area. The optical absorption edge is 850nm under the temperature of 25℃. The emission spectrum of the light source used with the sensor should overlap on both sides of the optical absorption edge. The displacement of this edge induced by teA good linearity of measuring curve can improve the resolution of valid measure-area. The optical absorption edge is 850nm under the temperature of 25℃. The emission spectrum of the light source used with the sensor should overlap on both sides of the optical absorption edge. The displacement of this edge induced by temperature changes modifies the fraction of light that falls into the absorption band, meaning that transmitted intensity will change. From several equations, the reflected light intensity is closely connected with the temperature of detected object. As the temperature climbs up, the ultimate output light intensity falls down nonlinearly. After that, we have proposed the feasibility to broaden the range of measurement from 20 ℃～80 ℃, as many references discussed, to 10 ℃～90 ℃. Therein two groups of curve about reflected light intensity induced by temperature through the computation of Matlab, three groups of curve on output intensity according to temperature variations, three groups of curve about detected voltage changes under different incident light intensities are concluded. From above, four valuable conclusions are brought into being..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 335 (2008)
A Method of Non-Effective Pixel Detection and Compensation of Un-Cooled Infrared Focal Plane Array
Tu Xia, Jiang Yadong, Luo fengwu, and Wang Liying
The non-effective pixels exist in the un-cooled infrared focal plane array (UFPA) inevitably, which has a bad effect on the UFPA imaging. Based on analyzing some kinds of algorithm on the non-effective pixels detection of un-cooled infrared focal plane array, a new method of detection and real-time compensation is presThe non-effective pixels exist in the un-cooled infrared focal plane array (UFPA) inevitably, which has a bad effect on the UFPA imaging. Based on analyzing some kinds of algorithm on the non-effective pixels detection of un-cooled infrared focal plane array, a new method of detection and real-time compensation is presented in this article to solve this problem. First of all, the best threshold of the non-effective pixels detection is searched according to the pixels′ response characteristics and the locations of the non-effective pixels are marked as well. When realizing on hardware, for an M×N UFPA, at any sampling time, a shift-register is used to store M data which is before the current sample data and the shift-register′s output is updated with the data which is at the same column while the upper row. Meanwhile, a common register is used to store the data which is at the same row while the previous column. Then, the interpolation theory is introduced to compensate the non-effective pixel. The approach proposed solves the difficulty of the non-effective pixels detection and compensation efficiently. For a 320×240 UFPA, the algorithm has been realized on an infrared image processing system based on FPGA and the effect of non-effective pixel on the imaging system is eliminated successfully..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 339 (2008)
Autofocus for Numerical Reconstruction in Digital Holographic Microscopy
Wang Huaying, Liu Jingbo, Wang Dayong, and Zhao Jie
Autofocusing is the key of numerical reconstruction in digital holographic microscopy. Based on Fresnel transform algorithm, the performance of six typical autofocusing evaluation functions are studied experimentally. A method which only uses part of the reconstruted image as autofocusing area is proposed to decrease tAutofocusing is the key of numerical reconstruction in digital holographic microscopy. Based on Fresnel transform algorithm, the performance of six typical autofocusing evaluation functions are studied experimentally. A method which only uses part of the reconstruted image as autofocusing area is proposed to decrease the calculating time. The results show that these functions have better unimodality, same adjusting focus range and accuracy, but the functions related with gradient are too slow to use in the numerical quasi-real time reconstruction. Fourier spectrum function is the optimum one for its minimum calculating time. The adjusting focus time can be decreased greatly by choosing a part of the reconstructed image as calculating area. For low signal-to-noise ratio hologram, the autofocusing accuracy and image quality can be improved by applying Wiener self-adaptive filter..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 343 (2008)
Adaptive Optics with Stochastic Parallel Gradient Descent Based on Subzones Coupling
Wang Sanhong, Liang Yonghui, Long Xuejun, Yu Qifeng, and Xie Wenke
Adaptive optics (AO) system based on stochastic parallel gradient descent (SPGD) method compensates a beam′s wave-front aberrations by controlling a wave-front corrector with direct optimization of the system′s performance metric. A new method of subzones coupling for modifying the conventional SPGD AO system is presenAdaptive optics (AO) system based on stochastic parallel gradient descent (SPGD) method compensates a beam′s wave-front aberrations by controlling a wave-front corrector with direct optimization of the system′s performance metric. A new method of subzones coupling for modifying the conventional SPGD AO system is presented to increase the convergence speed of the model-free adaptive optics system. A new lower-resolution subzonal wave-front corrector can be approximated by subdividing the wave-front corrector′s aperture into multiple subzones, all actuators associated with each subzone being treated as a whole controlling element. The coupling architecture of double wave-front correctors can be constructed by simultaneously controlling the approximated wave-front corrector and the original one with SPGD technique for a common performance metric. A numerical simulation model for an adaptive imaging system with 256-elements pixelated piston-type wave-front corrector was built up. The numerical simulation results show that this SPGD AO system based on subzones coupling holds faster convergence speed and better asymptotic normality than the conventional SPGD AO system..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 348 (2008)
Novel Optical Fiber Gas Sensing System Based on Fiber Bragg Grating Filtering
Wang Shutao
Based on law of Beer-Lambert, a novel optical fiber gas sensing system is designed to determine the concentration of gas. The narrow-band filtering characteristic of optical fiber Bragg grating is used by this system to produce the narrow spectrum light signal which is wanted in difference absorption measuring. This syBased on law of Beer-Lambert, a novel optical fiber gas sensing system is designed to determine the concentration of gas. The narrow-band filtering characteristic of optical fiber Bragg grating is used by this system to produce the narrow spectrum light signal which is wanted in difference absorption measuring. This system has characteristics such as full optical fiber light way and simple structure. The aspheric objective optical fiber collimator is adopted by this system to compose optical fiber gas sensing detector, which enhances the optic stability of the detector. The measuring sensitivity and stability are also further enhanced. Experimental data and results show that there is a high measuring sensitivity at 0.01%, and the measuring range goes beyond 5%..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 353 (2008)
Optical Fiber Transient High-Temperature Sensor and Dynamic Testing System
Wang Yutian, Yang Lili, and Lu Xinqiong
In order to provide a solution for transient high-temperature measurement under special circumstances, an optical fiber high-temperature sensor and dynamic calibration system based on the mechanism of blackbody radiance are designed. According to the basic principle of radiance temperature measurement and combining theIn order to provide a solution for transient high-temperature measurement under special circumstances, an optical fiber high-temperature sensor and dynamic calibration system based on the mechanism of blackbody radiance are designed. According to the basic principle of radiance temperature measurement and combining the sensor technology of optical fiber, “touchable-untouchable” measuring method and “fiber grating narrowband filters” technology are used to improve the measuring accuracy and decrease the influence of light background. Because the transient temperature changing very quickly with time and dynamic response error is great, a new principle is proposed. A high frequency modulated high power CO2 laser is used as the driving source to heat up the sensor calibrated. Using the temperature signal obtained, high-temperature dynamic calibration can be carried. The testing results show that the temperature measurement range is from 800～2000 ℃, and the system has many advantages such as high accuracy, fast response, anti-electromagnetic disturbance as well as high reliability. It solved the limitation of thermocouple, such as slow response and short life, and provided a new measuring method to transient high-temperature measurement in metallurgy, petroleum, industry and weapon development fields..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 358 (2008)
Analysis of Group-Velocities of Fundamental and Second-Harmonic Pulses in Third-Harmonic Generation of Ultrashort Pulse
Yang Yisheng, Han Wei, Zheng Wanguo, Li Fuquan, Wang Fang, Li Keyu, Jia Huaiting, Feng Bin, Cao Dingxiang, Dong Jun, and Tan Jichun
In the frequency conversion process of ultrashort pulses, due to group-velocity mismatch (GVM), conversion efficiency, crystal length and pulse bandwidth will affect each other and result in low efficiency or small bandwidth. Based on the nonlinear coupling equations, the analytical expressions about group-velocities oIn the frequency conversion process of ultrashort pulses, due to group-velocity mismatch (GVM), conversion efficiency, crystal length and pulse bandwidth will affect each other and result in low efficiency or small bandwidth. Based on the nonlinear coupling equations, the analytical expressions about group-velocities of fundamental (FH) and second-harmonic (SH) pulses are derived under the plane-wave and pump un-depletion approximations. THG mixing process with ultrashort pulses (FWHM ≈200 fs) input is numerically simulated in type-Ⅱ KDP crystals. The results show that conversion efficiency of 3ω exponentially decrease along with the square of difference between reciprocal of group-velocities of FH and SH pulses, which agree with our theoretical results. Conclusions of this paper are the necessary supplement to the group-velocity-matching relationship of THG, which will be useful for finding proper nonlinear crystals and choosing effective GVM methods in the THG process of ultrashort pulses..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 362 (2008)
Theoretical Analysis of Fabricating Near-field Optical Probe by Chemical Etching Method Combining Static Etching and Dynamic Etching
Yang Yongbin, and Xu Wendong
The mechanism and process of fabricating fiber probe by combining the static and dynamical chemical etching methods is analyzed. In the process of static etching, the height of the meniscus is obtained by the first-order approximate solution of the Young-Laplace equation. The influence of the velocity of the fiber moveThe mechanism and process of fabricating fiber probe by combining the static and dynamical chemical etching methods is analyzed. In the process of static etching, the height of the meniscus is obtained by the first-order approximate solution of the Young-Laplace equation. The influence of the velocity of the fiber movement on the shape of the fiber probe is analyzed in detail for different time range of the static and dynamic etching. Probes of various structures, such as large cone angle and short taper or multi-taper, can be formed with the combination of the static and dynamical chemical etching methods. The work establish the foundation for fabricating good probe experimentally and extending the application of scanning near field optical microscope (SNOM). The result of above theoretical analysis is the same to the preliminary result obtained on the experiment..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 367 (2008)
Study on the Performance Influence of the Thickness of the Metal film on the Optical Fiber Surface Plasma Wave Resonance Sensor
Zhang Xiaoli, Zeng Jie, Liang Dakai, and Zhao Zhiyuan
It not only compares the spectral characteristics of the optical fiber surface plasma resonance sensor between the boned and unbonded layer when they have the same thickness of the gold film, but also studies the optical fiber surface plasma resonance sensor at different thicknesses of the gold film when they have the It not only compares the spectral characteristics of the optical fiber surface plasma resonance sensor between the boned and unbonded layer when they have the same thickness of the gold film, but also studies the optical fiber surface plasma resonance sensor at different thicknesses of the gold film when they have the same thickness of the adhesive layer. All of the studies are based on the coating equipment SG-12SA. The result indicates that the resonant wavelength of the optical fiber surface plasma wave resonance sensor red-shift and shallow gradually when the fiber core and the gold film having adhesive layer compares to non-adhesive layer, When the thickness of the adhesive layer is unchanged, the resonant wavelength is also red-shift with the thickness of the gold film increasing. These results not merely provide reference for making high-performance optical fiber sensor, but provide instructional information for coating on the micro-diameter of three dimensional cylinders..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 373 (2008)
Crystallization of Amorphous Hydrogenated SiC Films by KrF Excimer Laser Annealing
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Amorphous hydrogenated silicon carbide(a-SiC∶H) films were annealed by KrF excimer laser to realize crystallization. a-SiC∶H films were prepared by plasma enhanced chemical vapor deposition (PECVD) and then irradiated by KrF excimer laser pulses at different power densities. The results indicate that laser annealing atAmorphous hydrogenated silicon carbide(a-SiC∶H) films were annealed by KrF excimer laser to realize crystallization. a-SiC∶H films were prepared by plasma enhanced chemical vapor deposition (PECVD) and then irradiated by KrF excimer laser pulses at different power densities. The results indicate that laser annealing at a proper density is an effective way to realize material crystallization, and the crystal size gets bigger as the incident laser power increases. It is observed from the micrograph that when the incident laser power is over 200 mJ/cm2, the phenomena of surface corrugation caused by thermal elastic wave come into being on the surface of films after laser annealing, and a-SiC∶H films are transformed by liquid crystallization. FTIR indicates that the content of hydrogen decreases, the peak of Si-C enhances and blue shift occurs, all of which imply the crystallization of a-SiC∶H films improves..
Acta Optica Sinica
- Publication Date: Jun. 18, 2020
- Vol. 28, Issue s2, 378 (2008)
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