Journals >Acta Photonica Sinica
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2016
Volume: 45 Issue 10
27 Article(s)
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Research Article
PAPR Reduction Method for CO-OFDM System Based on Improved Bat Algorithm
LIU Jian-fei, WANG Shao-ying, ZENG Xiang-ye, LU Jia, and WANG Meng-jun
To reduce Peak to Average Power Ratio (PAPR) in CO-OFDM systems, bat algorithm was applied for optimizing the sub-carrier phase. Moreover, the algorithm was improved aiming at the problems that the bat algorithm is easy to fall into local optimum and has low convergence precision. In the velocity updating formula, the To reduce Peak to Average Power Ratio (PAPR) in CO-OFDM systems, bat algorithm was applied for optimizing the sub-carrier phase. Moreover, the algorithm was improved aiming at the problems that the bat algorithm is easy to fall into local optimum and has low convergence precision. In the velocity updating formula, the bat's self study part, the inertia weight and learning factor were introduced to ensure the algorithm convergence speed and improve the convergence precision of the algorithm at the same time as much as possible, avoiding the occurrence of premature convergence. The simulation was carried out in a 100 Gb/s, 4QAM CO-OFDM system, and the simulation results show that the improved algorithm has been obviously improved in searching ability and accuracy. The PAPR can be reduced by about 5.48 dB and 0.52 dB compared with ones of the original OFDM and the BA-OFDM, respectively. The improved algorithm shows better effects on reducing PAPR..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1006001 (2016)
Sensing Characteristics of Daul S-shape Optical Fiber Structure
WANG Zhi-ping, GONG Hua-ping, XIONG Meng-ling, ZHAO Chun-liu, and DONG Xin-yong
A section of the single mode optical fiber stripping coated layer was discharged into two S-shape in a splicer at a distance of 25 mm and a Mach-Zehnder interferometer based on daul S-shape structure was formed. Part of the light can be excited into the cladding mode at the first S structure and return to the core modeA section of the single mode optical fiber stripping coated layer was discharged into two S-shape in a splicer at a distance of 25 mm and a Mach-Zehnder interferometer based on daul S-shape structure was formed. Part of the light can be excited into the cladding mode at the first S structure and return to the core mode at the second one. The S structure leads to the coupling between the core mode and the cladding mode and generates interference. Using the interference spectra to measure the response to external factors like temperature, refractive index, and micro displacement. Experimental results show that the sensitivities of temperature, refractive index and micro displacement are 69 pm/℃，132.64 nm/RIU，－178 pm/μm, respectively, and the measurement has a good linearity. The sensor has the merits of all-fiber structure, easy-fabricated and low-cost..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1006002 (2016)
2-order Rogue Solution of Hirota Equation and Its Transmision
LI Shu-qing, CHANG Feng, GUO Zun-guang, and LIU Yang
In order to study the 2-order rogue solution of Hirota equation and its transmision, the formation mehanism of the 2-order rogue was numerical analyzed and the characteristic of the 2-order rogue wave propagation in the fiber was simulated by the fast Fourier transform. It is found that the 2-order rogue wave can be reIn order to study the 2-order rogue solution of Hirota equation and its transmision, the formation mehanism of the 2-order rogue was numerical analyzed and the characteristic of the 2-order rogue wave propagation in the fiber was simulated by the fast Fourier transform. It is found that the 2-order rogue wave can be regarded as the two 1-order waves superposition. In the transmission process, the 2-order rogue wave is firstly split into two rogue waves, and the energy of the 2-order wave is reduced by half，and the distance between them is bigger but there is no mutual interference. Finally, the effects of self-steepening and self-frequency shift for 2-order rogue were numerical analyzed. The results show that self-steepening causes the energy of left wave bigger than right wave, and self-frequency shift makes the center of rogue wave nonlinear deviated, and the parameters decide the direction of deviate..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1006003 (2016)
Channel Estimation Algorithm with Low Pilot Overhead and High Accuracy for IMDD-OFDM Transmission System
BI Mei-hua, LI Jie-wei, YANG Guo-wei, ZENG Ran, LI Qi-liang, XIAO Shi-lin, and HU Wei-sheng
A low overhead and high accurate channel estimation algorithm was proposed and experimently verified in Intensity Modulation Direct Detection Orthogonal Frequency Division Multiplexing (IMDD-OFDM) optical transmission system. By fully considering system noise feature, this algorithm utilized the comb-type pilot insertiA low overhead and high accurate channel estimation algorithm was proposed and experimently verified in Intensity Modulation Direct Detection Orthogonal Frequency Division Multiplexing (IMDD-OFDM) optical transmission system. By fully considering system noise feature, this algorithm utilized the comb-type pilot insertion scheme, and combined the teachniques of symbol averaging and linear interpolation method within subcarriers, which could achieve a high estimation accuracy and a low overhead. The results are shown in simulaiton and theoretical derivation that, compared with the common channel estimations, the algorithm we proposed can achieve a better performance which is more close to the characteristic of real system channel. The experiment results demonstrate that, at a Bit Error Ratio (BER) of 3.8×10－3, this algorthim only with 0.78% pilot overhead can achieve the same performance to compare with that of the 20.31 % pilot overhead of normal frequency domain avageral algorithm. In additon, compared with other normal algorthims, our algorithm is irrelevant to the pilot overhead, can effectively reduce the mean squared error of channel estimation and achieve a high tolerance for the Gaussion noise of system, thus achieving relatively close performance to the real channel feature..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1006004 (2016)
Optical Fiber Vibration Measurement System with Temperature Compensation Function
YAO Guo-zhen, LI Yong-qian, SHANG Qiu-feng, and YANG Zhi
Aiming at the problem that the optical fiber vibration acceleration sensor is influenced by temperature and its sensitivity is low, an optical fiber vibration measurement system with temperature compensation function was designed. The ambient temperature, which is used to compensate for the vibration acceleration to reAiming at the problem that the optical fiber vibration acceleration sensor is influenced by temperature and its sensitivity is low, an optical fiber vibration measurement system with temperature compensation function was designed. The ambient temperature, which is used to compensate for the vibration acceleration to reduce the effect of temperature on the vibration measurement, was measured by a fiber Bragg grating. The tunable Fabry-Perot filter was used for wavelength demodulation and also as the fiber mirror to improve the sensitivity of the sensor. The mutual influences of vibration measurement and temperature measurement were analyzed and tested, the results show that the effect of the Fabry-Perot filter scanning on vibration measurement can be eliminated by data processing and the influence of vibration on temperature measurement is small.The temperature stability and sensitivity of the system were tested by experiments, which show that the maximum relative error of the vibration acceleration measurement is 1.65% under the temperature range of 25℃ and the sensitivity of vibration measurement is 107.70 mV/g..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1006005 (2016)
Optimum Performance of Optical Coherent Eavesdropping Receiver with Bandwidth Limitation in QPSK Systems
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Optical coherent eavesdropping receiver model with limited bandwidth is established in Quadrature Phase Shift Keying(QPSK) system. And equivalent filter model about bandwidth limitation is given. The received signal model is present in the presence of limited bandwidth. The interferences of other symbols on current symOptical coherent eavesdropping receiver model with limited bandwidth is established in Quadrature Phase Shift Keying(QPSK) system. And equivalent filter model about bandwidth limitation is given. The received signal model is present in the presence of limited bandwidth. The interferences of other symbols on current symbol are analyzed in detail with received signal constellation. Signal-to-noise ratio(SNR) is redefined and Bit Error Rate(BER) performance of receiver with limited bandwidth is derived based on Decision Aided Maximum Likelihood(DAML) phase estimation. The optimum sampling timing offset and bandwidth are also analyzed. Simulation results show that the maximum SNRs per bit we defined correspond to the minimum BER under different bandwidth. The optimum sampling timing offset and bandwidth are different with different type of filter, but the optimum ones can be found by SNR we defined. And with Optical Signal-to-Noise Ratio(OSNR) increasing, the performance of DAML phase estimation receiver is degraded by bandwidth limitation..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1006006 (2016)
Dynamic Characteristic Analysis on Streak Image Tube with High Temporal Resolution
LIU Rong, TIAN Jin-shou, MIAO Run-cai, WANG Qiang-qiang, WEN Wen-long, LI Yan, WANG Jun-feng, XU Xiang-yan, LU Yu, LIU Hu-lin, and WANG Xing
Aim to high temporal resolution of the streak image tube in streak camera, the factors which influence the physical temporal dispersion, technical temporal dispersion and time jitter of the sweep circuit were discussed. The streak image tube was optimized, in which a pair of traveling wave deflectors was located beforeAim to high temporal resolution of the streak image tube in streak camera, the factors which influence the physical temporal dispersion, technical temporal dispersion and time jitter of the sweep circuit were discussed. The streak image tube was optimized, in which a pair of traveling wave deflectors was located before a magnetic solenoid lens. The inner time-varying electric field of traveling wave deflectors was simulated by CST electromagnetic studio. And the propagation velocity of electromagnetic wave was calculated. The results show that when leg length is 8 mm, leg width is 1mm, interval is 0.24 mm, pin length is 2.5 mm, deflector thickness is 1 mm and deflector length is 17.12 mm, the moving velocity of electrons and propagation velocity of the electromagnetic wave are matching. Based on the electron trajectory tracing method and the Rayleigh criterion, dynamic temporal and spatial characteristics of the streak image tube were analyzed, a dynamic temporal resolution of 200 fs in single sweep mode, dynamic temporal resolution of 208 fs in synchronized sweep mode, and a dynamic spatial resolution of above 20 lp/mm were obtained..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1012001 (2016)
Evaluation Model of Detected Ability for Ground-based Electro-optic Telescope to Space Debris
HU Jing-jing, LIU Jing, CUI Shuang-xing, ZHANG Yao, CHENG Hao-wen, and WU Xiang-bin
In order to increase operating efficency of the ground-based electro-optic telescope for space debris observation，the evaluation model of detected ability for ground-based electro-optic telescope model was constructed. The model concludes geometry crossing of space debris, calculation for signal irradiation of space deIn order to increase operating efficency of the ground-based electro-optic telescope for space debris observation，the evaluation model of detected ability for ground-based electro-optic telescope model was constructed. The model concludes geometry crossing of space debris, calculation for signal irradiation of space debris and background source, projecting for source signal to sensor plane, and calculation of detected signal to noise as basis of detectable judgement, etc. Observation test about geostationary earth orbit with 1m telescope was done for modelling verification. The conclusion shows that four background stars in Tycho-2catalogue crossing field of view in observation testwas observed, the number is same with simulation. the maximum difference magnitude for space debris of test compared to simulation was as much as 1.58, and it was mainly due to the feature of debris such as shape, it was with reason. The ground-based electro-optic telescope model based in signal-to-noise detected theory wsa reasonable,it can support suggestions for detected device construction, observed strategy design, etc..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1012002 (2016)
Location Method of Static Object Based on Monocular Vision
SHAO Xiao, and TAO Jian-wu
Aiming at the background of sense and avoiding of unmanned aerial vehicle, a monocular vision method for distance measurement from motion was proposed. Firstly, two different images were chose from a sequence of images for the same target in different position. Then, feature points could be extracted and matched througAiming at the background of sense and avoiding of unmanned aerial vehicle, a monocular vision method for distance measurement from motion was proposed. Firstly, two different images were chose from a sequence of images for the same target in different position. Then, feature points could be extracted and matched through scale-invariant feature transform algorithm for the two images. Through analysis the different positions for the same feature point on different images and combined with the movement parameters of the aircraft, the information between the aircraft and the obstacle could be got. With the proposed method, the target was located at different locations. The experimental results show that the measurement accuracy and effectiveness of the method can meet the demand of avoidance..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1012003 (2016)
Experimental Investigation of an 1 150 nm Yb-doped Fiber Laser
CHEN Hong-wei, SHEN Yan-long, TAO Meng-meng, LUAN Kun-peng, HUANG Ke, YU Li, YI Ai-ping, and FENG Guo-bin
An all-fiber 1 150 nm long-wavelength fiber laser oscillator was demonstrated by using a pairs of fiber brag grating as the laser cavity, a piece of Yb-doped as the gain media and a 976 nm laser diode as the pump source. 1 150 nm band single-mode fiber laser with max output power of 12.7 W is obtained at room temperatuAn all-fiber 1 150 nm long-wavelength fiber laser oscillator was demonstrated by using a pairs of fiber brag grating as the laser cavity, a piece of Yb-doped as the gain media and a 976 nm laser diode as the pump source. 1 150 nm band single-mode fiber laser with max output power of 12.7 W is obtained at room temperature and the optical-to-optical conversion efficiency is up to 42.33%. The central wavelength is 1 150.48 nm, the 3 dB spectral width is 0.45 nm and the optical signal-to-noise ratio is 38 dB. The research results will make a contribution to the further development of high-power 1 150 nm long-wavelength fiber laser oscillator..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1014001 (2016)
Bidirectional Erbium-doped Fiber Laser Mode-locked by Single-wall Carbon Nanotubes
WANG Shi-zhong, ZHANG Zu-xing, and HU Fang-ren
The bidirectional operation of a single-wall carbon nanotube-based passively mode-locked erbium-doped soliton fiber laser without isolator, is demonstrated with stable output pulse trains simultaneously from both directions of the laser cavity. The fiber laser consists of wavelength division multiplexer, erbium-doped fThe bidirectional operation of a single-wall carbon nanotube-based passively mode-locked erbium-doped soliton fiber laser without isolator, is demonstrated with stable output pulse trains simultaneously from both directions of the laser cavity. The fiber laser consists of wavelength division multiplexer, erbium-doped fiber, optical coupler, carbon nanotube, single-mode fiber and polarization controller. By adjusting the pump power and polarization controller to analyse the output characteristics of experimental device under different pump powers , the center wavelengths of the two opposite pulses can be changed from 1 558~1 560 nm. The clockwise pulse width can be varied from 854~959 ps. The counter clockwise pulse width can be changed from 247~624 ps. Especially, the pulse split of the counterclockwise pulse trains has been observed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1014002 (2016)
Chaotic Signal Generation with Low Time-delay Signature Based on a Semiconductor Laser Subject to Double Filtered Optical Feedback
LU Dong, ZHONG Zhu-qiang, XIA Guang-qiong, and WU Zheng-mao
Two Fabry-Perot interferometers were taken as double external cavities to construct a Double Filtered Optical Feedback Semiconductor Laser (DFOF-SL) for achieving chaotic signal with low time-delay signature, and the influences of feedback time, feedback strength, filter bandwidth, and the frequency detuning between thTwo Fabry-Perot interferometers were taken as double external cavities to construct a Double Filtered Optical Feedback Semiconductor Laser (DFOF-SL) for achieving chaotic signal with low time-delay signature, and the influences of feedback time, feedback strength, filter bandwidth, and the frequency detuning between the central frequency of the filter and the solitary laser on the time-delay signature evolution were theoretically investigated. The results show that, when the difference of the feedback time between the two external cavities approximately equals to a half of the relaxation oscillation period of the laser, the chaotic signal with relatively weak time-delay signature can be obtained. Moreover, through suitably selecting feedback strength, filter bandwidth, and the frequency detuning between the central frequency of the filter and the solitary laser, the time-delay signature can be further suppressed. Finally, based on the map of time-delay signature evolution in the parameter space of filter bandwidth and frequency detuning, the optimal feedback parameter regions for achieving chaotic signal with low time-delay signature have been determined..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1014003 (2016)
Design of Surface Plasmon Polariton Nano-laser
WEI Lai, LI Fang, and ZHOU Jian-xin
A surface plasmonic nano-laser structure based on a nanowire/gap/metal layer was proposed. The models produce a significant field enhancement effect through the mode-coupling between nanowire and metal layer. Modal properties and lasing threshold under different geometric shapes and parameters were investigated and anaA surface plasmonic nano-laser structure based on a nanowire/gap/metal layer was proposed. The models produce a significant field enhancement effect through the mode-coupling between nanowire and metal layer. Modal properties and lasing threshold under different geometric shapes and parameters were investigated and analyzed by the finite element method. Simulation results reveal that this kind of nano-laser has a low propagation loss and high field confinement ability, its minimum propagation loss is only 0.013 3 and the minimum normalized mode area is only 0.007. The results provide theory and technique support to the field of new nano-laser design..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1014004 (2016)
Investigation of Sound Isolation in Composite Structure of Local Resonant Phononic Crystals
DU Jun, QI Peng-shan, JIANG Jiu-long, DONG Ya-ke, and ZHANG Jia-long
A local resonant phononic crystal model including four symmetrical vibrators was proposed. By changing the material components of the vibrator, this phononic crystal model could exist band gap and sound isolation peaks in different frequency range. In order to widen the frequency range of the sound isolation, a method A local resonant phononic crystal model including four symmetrical vibrators was proposed. By changing the material components of the vibrator, this phononic crystal model could exist band gap and sound isolation peaks in different frequency range. In order to widen the frequency range of the sound isolation, a method was proposed to composite different structures. The structure plays a good sound isolation respectively in different frequency, and the composite structure can realize the widening of sound isolation range. The key factors affecting the sound isolation effect are studied through the finite element method. The results show that, the method can widen sound isolation range effectively, and the research provide an effective theoretical reference for wideband sound isolation of phononic crystals.
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1016001 (2016)
Preparation and Properties of Novel Dual Halide Co-doped Chalcogenide Multispectral Glasses
ZHANG Teng-yu, NIE Qiu-hua, WANG Xun-si, SHEN Xiang, WANG Guo-xiang, ZHU Qing-de, DAI Shi-xun, LI Jun-peng, and ZHANG Rui
A series of 65GeS2-15Ga2S3-(20-x)CsCl-xCsI(x=0, 5, 10, 15, 20) chalcogenide glasses were prepared by the traditional melt-quenching method. By means of the measurement of the density, micro-hardness, Visible-Near Infrared absorption spectra, Infrared optical transmission spectra, Raman spectra, X-ray diffraction curvesA series of 65GeS2-15Ga2S3-(20-x)CsCl-xCsI(x=0, 5, 10, 15, 20) chalcogenide glasses were prepared by the traditional melt-quenching method. By means of the measurement of the density, micro-hardness, Visible-Near Infrared absorption spectra, Infrared optical transmission spectra, Raman spectra, X-ray diffraction curves and glass transition temperature Tg, the optical characters of this kind of glasses were studied systematically. The results show that, the series of glass samples have a wide composition range of glass formation and a good transparency in the entire 0.42～12 μm spectral region . With increasing of the content of the CsI, the density increases progressively. With increasing of the content of the CsCl, the optical band gap and microhardness increase gradually. Tg of glass samples changes with the change of the molar ratio of Cl－/I－. When the ratio located at 1, Tg hits its rock bottom..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1016002 (2016)
Iris Acquiring Optical System Design with Wavefront Coding
ZHANG Ji-yan, HUANG Yuan-qing, and XIONG Fei-bing
An iris acquiring optical system with wavefront coding technique was designed, which can increase the depth of the field and get image at natural state without restriction. By applying the conventional imaging evaluation metric, Strehl ratio and encircled energy were used as the imaging features, and the wavefront codiAn iris acquiring optical system with wavefront coding technique was designed, which can increase the depth of the field and get image at natural state without restriction. By applying the conventional imaging evaluation metric, Strehl ratio and encircled energy were used as the imaging features, and the wavefront coding system was design with ZEMAX, then a better trade-off between insensibility to defocus and restorability was obtained. The depths of focus of the system with cubic phase mask and modified cubic phase mask and the conventional system were compared. The result suggests the depth of focus of the iris acquiring system with cubic phase mask is the best which can attain by a factor of 8 over conventional iris acquiring system. The design increases the distance of the iris acquiring which has some reference value to the design of the iris image acquiring system at natural state..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1022001 (2016)
Based on Image Autocollimation Automatic Focus Technology
XIAO Zuo-jiang, ZHU Hai-bin, and XU Zhi-gang
According to the requirements of focusing accuracy and the imaging characteristics of the CCD camera, an automatic focusing system of aerial camera which is based on image processing technology was proposed. It was based on the self-made resolution target, the image sharpness function and the optimized mountain climbinAccording to the requirements of focusing accuracy and the imaging characteristics of the CCD camera, an automatic focusing system of aerial camera which is based on image processing technology was proposed. It was based on the self-made resolution target, the image sharpness function and the optimized mountain climbing algorithm. The calibration of the aerial camera's defocusing amount caused by temperature and atmospheric pressure were realized by using the self collimation and the defocusing compensation method. Through the introduction of aircraft altitude data to calculate the defocusing amount and the correction were achieved by using the self collimation focusing technology. The automatic focusing test experiment was carried out and the results show that, the system can satisfy the requirements of fast and high precision focusing of the aerial camera, the calibration error is less than 1/2 depth of the camera..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1022002 (2016)
Design of Dual-Band, High Zoom Ratio and Continuous Co-focal Optical System
LI Xi -jie, LIU Jun, and CHEN Yang
In order to increase the high resolution detection capabilities of zoom optical system in a complex environment, and to solve the problems of the slow conversion speed of the optical path and differences among the object information of different bands in the multi-band optical system, a visible (0.38～0.76 μm) and middlIn order to increase the high resolution detection capabilities of zoom optical system in a complex environment, and to solve the problems of the slow conversion speed of the optical path and differences among the object information of different bands in the multi-band optical system, a visible (0.38～0.76 μm) and middle infrared (3～5 μm) continuous co-caliber common zoom optical system with working focal length of 7.52~98.35 mm and zoom ratio of 13×was designed . The zoom ratio variation of visible and middle infrared at any zoom position was analyzed based on the positive compensation zoom group theory. The three thin achromatic lens focal length compensation theory and dual-band expression were derived. The power of zoom group and compensation group were matched rationally, making the system have the same zoom ratio at any zoom position and focal length, which improved consistency of dual-band target information. According to requirements, the dual-band athermal optical system with the temperature of －40~+60℃ was designed with the use of optical passive. The results show that the system has compact structure, fast response and good overall image quality, which can achieve all-weather day and night work..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1022003 (2016)
High Power Picosecond Thulium-doped Fiber MOPA with a High Energy Soliton Seed
CHEN Rong, YANG Jian-long, QI Xiang-ning, XU Jian-qiu, and TANG Yu-long
Thulium-doped fiber Master Oscillator Power Amplifier(MOPA) was demonstrated for high power picosecond laser within the 2 μm wavelength range with a high energy soliton seed. The master oscillator was a passively mode-locked fiber laser, which can generate high energy soliton pulses with 50 ps pulse width, a repetitionThulium-doped fiber Master Oscillator Power Amplifier(MOPA) was demonstrated for high power picosecond laser within the 2 μm wavelength range with a high energy soliton seed. The master oscillator was a passively mode-locked fiber laser, which can generate high energy soliton pulses with 50 ps pulse width, a repetition frequency of 55.6 MHz and a spectral width of ~21 nm by managing and optimizing its dispersion. The seed pulse was stretched to ~600 ps by a spool of passive fiber with anomalous dispersion before sent to two amplified stages. Finally, average power of about 23 W and pulse duration of 660 ps were achieved before the pulse compressor. With a grating-pair compressor, the chirped pulse can be compressed to about 0.9 ps..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1023001 (2016)
All-solid Three-core Photonic Crystal Fiber Polarization Splitter
LIU Zhao-lun, DU Hai-li, and WANG Ming
An all-solid three-core Photonic Crystal Fibers (PCFs) polarization splitter based on tellurite glass was researched. When one polarization state of light is close unlimitedly to resonance coupling conditions, the other polarization state is far from the resonance coupling conditions resulting in the weak coupling degrAn all-solid three-core Photonic Crystal Fibers (PCFs) polarization splitter based on tellurite glass was researched. When one polarization state of light is close unlimitedly to resonance coupling conditions, the other polarization state is far from the resonance coupling conditions resulting in the weak coupling degree. Based on the resonance coupling phenomenon in the three-core PCFs, different polarization states can be separated. The simulation shows that the polarization beam splitter possesses the characteristics of short-length, ultra-band-width and high-extinction ratio at the wavelength of 1 550 nm. The length of this splitter is only 1.14 mm and its extinction ratio can reach －101.27 dB. The bandwidth of extinction ratio less than －20 dB reaches 100 nm, and the bandwidth of extinction ratio less than －10 dB reaches up 350 nm which covers E+S+C+L+U wave bands. This all-solid photonic crystal fiber polarization splitter not only has superior performance, simple structure, its all-solid structural design also can effectively avoid the circumstance of air-holes collapse during the fabrication of photonic crystal fibers, which provides an effective way for better performance polarization splitter..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1023002 (2016)
Multi-wavelength Scattering Characteristics of a SPASER-based Off-centre Gold Shell Nanoantenna
WANG Mian, ZHANG Hao-peng, XU Tian, ZHOU Jian-hong, and ZHOU Jun
Based on the mechanism of the Surface Plasmon Amplification by Stimulated Emission of Radiation (SPASER), an off-centre gold shell nanoantenna consisted of the silica-gold-silica three-layer core-shell was proposed and its multi-wavelength light scattering characteristics were numerically analyzed by using the Finite EBased on the mechanism of the Surface Plasmon Amplification by Stimulated Emission of Radiation (SPASER), an off-centre gold shell nanoantenna consisted of the silica-gold-silica three-layer core-shell was proposed and its multi-wavelength light scattering characteristics were numerically analyzed by using the Finite Element Method (FEM). For the SPASER-based nanoantenna, the results show that, the scattering wavelength number increases with the increasing of the silica core eccentricity and the scattering light intensity is greatly enhanced. When the eccentricity of silica core is 9 nm, the proposed nanoantenna has four intensity resonance peaks which are located at 615 nm, 656 nm, 724 nm and 847 nm respectively, and the corresponded scattering intensities are much higher than that of the non-SPASER one, about 104 times. Moreover, the scattering wavelengths of the proposed nanoantenna can be easily adjusted by changing the polarization angle of the incident light. The SPASER-based nanoantenna would be useful to design the multi-wavelength laser devices in nanoscale..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1024001 (2016)
Design of Slot Yagi-Uda Nanoantennas and Their Broadband Absorption Properties
ZHU Lu, WANG Yang, LIU Yuan-yuan, HUANG Zhi-qun, and CI Bai-shan
Aim at the problem that the energy collection of traditional photovoltaic cells is susceptible to environment and illumination time constraints, a slot Yagi-Uda nanoantenna unit and array was proposed for solar energy harvest. By adopting the finite difference time domain method, the influence of gap spacing on the nanAim at the problem that the energy collection of traditional photovoltaic cells is susceptible to environment and illumination time constraints, a slot Yagi-Uda nanoantenna unit and array was proposed for solar energy harvest. By adopting the finite difference time domain method, the influence of gap spacing on the nano antenna far field directivity and the near field distribution was analyzed. The influence of the absorption characteristics of slot Yagi-Uda nanoantenna array and the different slot spacing on the array antenna absorption rate was studied. The study of far field directivity shows that, when the slot spacing increases to a certain distance, the antenna far-filed pattern appears multi-sidelobe and a new radiation pattern. The analysis of the near field thows that, the new radiation pattern is derived from the high order mode of localized surface plasmon. The simulation results of the antenna array absorption rate show that, in the waveband range from 400nm to 1500nm, with the increase of slot spacing, the absorption rate shows a trend of rising. When the slot spacing is equal to 80nm, the antenna absorption rate is higher in the band range from 400nm to 660nm and the range from760nm to 1300nm, the absorption peak value can reach 98%. The absorption rate exceeds 50% as a benchmark, when the slot spacing is equal to 80nm, the absorption band is widest..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1024002 (2016)
Tripartite Entanglement Dynamics in a Equidistance Cavities Coupled by Fibers
QIU Chan-dong, and LU Dao-ming
When the three separated equidistance single-mode cavities were positioned at the three vertices of an equilateral triangle, the characteristic of the tripartite entanglement among the cavities and that among atoms in the system was studied. The situation was considered which three identical two-level atoms are separatWhen the three separated equidistance single-mode cavities were positioned at the three vertices of an equilateral triangle, the characteristic of the tripartite entanglement among the cavities and that among atoms in the system was studied. The situation was considered which three identical two-level atoms are separately trapped in cavities. Each atom resonantly interacts with cavity via a one-photon hopping. The evolution of the state vector of the system was given when the total excitation number of the system equals one. Negativity was adopted to quantify the degree of tripartite entanglement among three subsystems. The tripartite entanglement dynamics among atoms and that among cavities were studied. The influences of cavity-fiber coupling constant on the tripartite entanglement among atoms and that among cavities were discussed. The results obtained using the numerical method show that, the tripartite entanglement among atoms and that among cavities are weakened with increase of cavity-fiber coupling coefficient..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1027001 (2016)
Hyperspectral Image Classification with Combination of Weighted Mean Filter and Manifold Reconstruction Preserving Embedding
HUANG Hong, ZHENG Xin-lei, and LUO Fu-lin
Hyperspectral Image (HSI) contains a large number of spectral bands that easily results in the curse of dimensionality. The traditional classification methods just apply the spectral information while they ignore the spatial information. To address this problem, a dimensionality reduction algorithm combining Weighted MHyperspectral Image (HSI) contains a large number of spectral bands that easily results in the curse of dimensionality. The traditional classification methods just apply the spectral information while they ignore the spatial information. To address this problem, a dimensionality reduction algorithm combining Weighted Mean Filter (WMF) and Manifold Reconstruction Preserving Embedding (MRPE) was proposed in this paper. According to the spatial consistency property of HSI, firstly, the method applies WMF to all pixels which can reduce the spectral difference of data points from the same class. Then, the weights of the spatial neighbor points are enhanced in manifold reconstruction. This method effectively extracts the discriminant features and achieves the dimensionality reduction. Experimental results on PaviaU and Urban data sets show that the proposed method has better classification accuracy than other algorithms. When 5% and 1% of training samples were randomly selected from the two data sets, the overall accuracies based on MRPE can reach 98.76% and 80.21%. The proposed method enhances the low-dimensional manifold representation with the spatial information and improves the performance of HSI classification..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1030001 (2016)
Terahertz Emission Dependence on the Polarization Angle between Two-color Lasers
XIE Jun, FAN Wen-hui, and TANG Jie
The influence of the polarization angle between two-color lasers on the Terahertz (THz) emission was investigated based on a modified two-dimensional transient current model. By changing the polarization angle between the fundamental frequency laser and its second harmonic laser beam, it is found that, the emitted THz The influence of the polarization angle between two-color lasers on the Terahertz (THz) emission was investigated based on a modified two-dimensional transient current model. By changing the polarization angle between the fundamental frequency laser and its second harmonic laser beam, it is found that, the emitted THz amplitude varys periodically with the chaning of the polarization angle in laser plasma, and the optimal angle is also changed with the different laser intensity. Under the comparatively low laser intensity (≤2×1014W/cm2), the THz amplitude can reach the maximum when the two-color lasers have the same polarization. However, the optimal angle will increase with the increasing of the total laser intensity when the laser intensity is high enough(>2×1014W/cm2). The electron density was firstly used to analyze this phenomenon under comparatively low laser intensity and then the residual drift current was utilized to reveal the underlying physical mechanism. It was found that, the residual current density is the essential source of the THz waves and which can determine the intensity of THz emission.
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1030002 (2016)
Spectral Characteristics Analysis of Laser-induced Nitrogen in Organic Materials
YU Jian-hua, DONG Mei-rong, ZHANG Bo, PAN Yue, SHENG Yue-liang, LU Zhi-ming, and LU Ji-dong
To choose the organic material benzamide containing benzene ring and the C-N structure as a model sample, the samples with different nitrogen content were prepared for the Laser-Induced Breakdown Spectroscopy (LIBS) experiment. The experiments were performed under different atmospheres (air and argon) to study the inflTo choose the organic material benzamide containing benzene ring and the C-N structure as a model sample, the samples with different nitrogen content were prepared for the Laser-Induced Breakdown Spectroscopy (LIBS) experiment. The experiments were performed under different atmospheres (air and argon) to study the influence of atmosphere on the excitation characteristics of nitrogen in organic materials with different laser energy, then the correlation between nitrogen spectral information and N concentration was established. The results show that, under the air condition, the spectral lines of atomic N of the samples are difficult to be detected, which indicates that the spectral lines of atomic N detected in the atmospheric environmentis mainly from the emision of atomic N contained in air (79% N2 in air). Under the condition of air or argon atmosphere, the molecular CN emission can be both detected and there exists a correlation relationship between the CN emission and N concentration, which is related to the atmosphere and laser energy. Under the conditon of argon, the good correlation relationship exeists both under low and high laser energy due to the formation of CN is from the sample. Under the condition of air, environment there is a good correlation relationship under a lower energy but less under a high energy (R2 higher than 0.9), which indicates that, in air environment, the CN is mainly from the sample under the low energy while the high laser energy causes the formation of CN strongly influenced by nitrogen in the air..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1030003 (2016)
Study and Fabrication Broad Spectral Absorbing Film in Second-order Correlated Imaging System
FU Xiu-hua, XIONG Shi-fu, LIU Dong-mei, ZHANG Jing, and CHENG Hui-ting
According to the demand for inhibiting background of the correlation system, Al, Cr and SiO2 were choosed as the coating materials. Based on the absorption theory, a broad spectrum absorbing film was designed by combining with the film design software, and by using the vacuum deposition technology, the film samples werAccording to the demand for inhibiting background of the correlation system, Al, Cr and SiO2 were choosed as the coating materials. Based on the absorption theory, a broad spectrum absorbing film was designed by combining with the film design software, and by using the vacuum deposition technology, the film samples were prepared. The internal stress of the film was reduced by stepped vacuum annealing, and the problem of film adhesion was solved. Using the interactive analysis and reverse inversion methods to analyze the testing results, the thickness of sensitive thin layers was controlled precisely by optimizing the process parameters, as a result, and the thickness control error was reduced. The average absorptivity of prepared absorbing film is 99.1% at the band of 400～1 100 nm, which meets the requirements of the system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 10, 1031001 (2016)
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