Contents
2009
Volume: 29 Issue 3
52 Article(s)
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Atmospheric Optics and Oceanic Optics
Analysis on Wavefront Errors of Active Deformable Mirror
Yang Licheng, and Ling Ning
Wavefront errors of the active deformable mirror are analyzed and experimentally studied.Based on the theoretical and experimental wavefront errors of the active deformable mirror, with key parameters gotten by the finite element method about compensating capabilities of the low-frequency errors for 300 mm aperture andWavefront errors of the active deformable mirror are analyzed and experimentally studied.Based on the theoretical and experimental wavefront errors of the active deformable mirror, with key parameters gotten by the finite element method about compensating capabilities of the low-frequency errors for 300 mm aperture and 1926 mm radius of curvature,37-element spherical active deformable mirror, has been fabricated. The peak-valley value and root-mean-square are 0.545λ (λ, warelength) and 0.081λ before correction, while 0.239λ and 0.031λ are achieved after correction in experiments.The techniques and craftubrk, such as mirror surface machning and actuator tip cementation, were explored..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 569 (2009)
Experimental Validation and Phase Retrieval Algorithm of Complicated Pupil Wavefront
Mao Heng, Wang Xiao, and Zhao Dazun
As a preferred wavefront sensing (WFS) method, the modified G-S (MGS) algorithm, which is classified as the iterative-transform algorithm of phase-diverse phase retrieval (PDPR), retrieves the phase distribution at pupil from some known point spread function (PSFs) at defocus planes. By using multiple diversities and pAs a preferred wavefront sensing (WFS) method, the modified G-S (MGS) algorithm, which is classified as the iterative-transform algorithm of phase-diverse phase retrieval (PDPR), retrieves the phase distribution at pupil from some known point spread function (PSFs) at defocus planes. By using multiple diversities and proper phase unwrapping methods, this algorithm can produce unique phase estimation within a large dynamic range. But for non-connected pupil, the path-independent phase unwrapping inside MGS is invalid owing to fake value of the points located in obstructed areas of pupil. Some detailed modifications about MGS are given. Then, a modified path-independent phase unwrapping algorithm is proposed based on the principle of least difference phase transition (LDPT), which can automatically optimize unwrapping steps and paths according to the pupil structure. Experiments have been implemented for MGS, and the adaptability of the proposed phase unwrapping algorithm has been validated. Compared with the measurement of interferometer, the WFS accuracy of MGS algorithm is calibrated..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 575 (2009)
Experimental Research for Real-Time Beam Cleanup in Turbulence Based on Stochastic Parallel-Gradient-Descent Method
Wang Sanhong, Liang Yonghui, Long Xuejun, Xie Wenke, Mao Hongjun, and Yu Qifeng
Adaptive optics can be used to compensate wave-front aberrations of output beam from high-power laser system for improving beam quality. To investigate the feasibility of adaptive optics method based on the stochastic parallel gradient descent (SPGD) for beam cleanup, a SPGD adaptive optics system with iterative rate oAdaptive optics can be used to compensate wave-front aberrations of output beam from high-power laser system for improving beam quality. To investigate the feasibility of adaptive optics method based on the stochastic parallel gradient descent (SPGD) for beam cleanup, a SPGD adaptive optics system with iterative rate of 100 Hz is built up, in which a high-speed photodetector is used as the measurement device of the system′s performance evaluation function, and a high-speed deformable mirror is served as the wave-front corrector. Dynamic wave-front aberrations caused by the heat flow turbulence of a resistance coil, are corrected in-real-time by the SPGD adaptive optics system. The experimental results show that the above-mentioned system can correct dynamic wave-front aberrations changing in the frequency range of 4 Hz below, resulting in both a 2.2-fold increase of the energy and a 1.4-fold increase of the stability of the far-field spot in the pinhole. It is indicated that the SPGD adaptive optics method is feasible for beam cleanup system..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 582 (2009)
Adaptive Optics System Based on Combinational Deformable Mirror for Improving Wavefront Spatial Correction Capability
Yang Huafeng, Rao Changhui, Zhang Yudong, and Jiang Wenhan
A new kind of adaptive optics (AO) system, in which several deformable mirrors (DMs) with optical conjugation relationship are combined to improve wavefront spatial correction capability, is proposed. The surface displacement of combinational deformable mirror (CDM) is introduced. Based on theoretical analysis, the intA new kind of adaptive optics (AO) system, in which several deformable mirrors (DMs) with optical conjugation relationship are combined to improve wavefront spatial correction capability, is proposed. The surface displacement of combinational deformable mirror (CDM) is introduced. Based on theoretical analysis, the integrated AO system with CDM that consists of two same deformable mirrors with the square arrays is built. The correction performance for the first 35 order Zernike aberrations is calculated and its closed-loop effect for correcting real aberrations is validated experimentally. The results indicate that CDM in the AO system can correct aberrations effectively as the same as one single DM with more actuators by using the direct-gradient control algorithm steadily in closed-loop, and the correction capability of the CDM is better than that of only one DM. This design can improve wavefront spatial correction capability by increasing the number of actuators and the coupling coefficient. So it can be used for compensating high-order aberrations instead of one single costly DM with more actuators for the same performance..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 587 (2009)
Influence of Particle Mie Scattering on Differential Optical Absorption Spectroscopy
Shao Litang, Wang Shimin, Tang Guanghua, and Xu Chuanlong
The inversion accuracy of gas concentration is influenced by the extinction derived from the Mie scattering of dust particles when the differential optical absorption spectroscopy (DOAS) is applied to on-line monitoring exhaustion of fixed pollution source. Simulation and experimental results for particles with diameteThe inversion accuracy of gas concentration is influenced by the extinction derived from the Mie scattering of dust particles when the differential optical absorption spectroscopy (DOAS) is applied to on-line monitoring exhaustion of fixed pollution source. Simulation and experimental results for particles with diameter of 1～10 μm, show the intensity of particle scattering is determined by particle-size distribution and number concentration. With the increase of particle size and number concentration, the differential optical density of gases rises. Accordingly, the frequency characteristics of the differential optical density curves have also been changed. The influence of dust Mie scattering on differential optical density cannot be eliminated by polynomial filter in traditional DOAS algorithm and the inversion results of gas concentration are greatly deviated from true value..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 594 (2009)
Fiber Optics and Optical Communications
Analysis of the Accumulation of Crosstalk in Optical Cross-Connects Based on the Benes Networks
Guan Aihong, Zhang Hongmei, Wang Yuhua, and Fu Hongliang
Optical cross-connects (OXCs) are key elements in all-optical WDM networks. OXC nodes generally consist of demultiplexers (DMUXs), space switching networks and multiplexers (MUXs). These nonideal devices give rise to signal leakage to the unintended channels and lead to the generation of crosstalk. Optical crosstalk imOptical cross-connects (OXCs) are key elements in all-optical WDM networks. OXC nodes generally consist of demultiplexers (DMUXs), space switching networks and multiplexers (MUXs). These nonideal devices give rise to signal leakage to the unintended channels and lead to the generation of crosstalk. Optical crosstalk imposes a major limit to the practical implementation of optical cross-connects. Intraband crosstalk characteristics of OXC composed by dilated Benes (DB) network and generally modified dilated Benes (GMDB) network are studied. Results show that OXC composed by DB and GMDB network can remove first order crosstalk successfully. At the same time, the power penalty induced by intraband crosstalk is studied by numerical simulation. Compared with DB network, GMDB network can eliminates crosstalk effectively. Simulations have been followed by experimental measurements. Experiments have confirmed and highlighted the beneficial effect of realizing OXCs architectures with GMDB networks. The crosstalk level of optical devices required in GMDB network is about 5 dB lower than that in DB network to keep the power penalty below 1 dB at the bit error rate of 10-9..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 602 (2009)
Orthogonal Signals 100 km Transmission over Standard Fiber Using Mid-Span Spectral Inversion by Four-Wave Mixing in a Semiconductor Optical Amplifier
Wang Kuiru, Liu Bo, Xin Xiangjun, Zhang Qi, Ma Jianxin, Yu Chongxiu, and Zhang Jinlong
155 Mb/s～10 Gb/s orthogonal FSK/IM signal’s transmission over 100 km of standard fiber based on mid-span spectral inversion is experimentally demonstrated. The phase-conjugation is achieved by four-wave mixing in an optimized semiconductor optical amplifier (SOA), which solves the dispersion problem of the FSK/IM ortho155 Mb/s～10 Gb/s orthogonal FSK/IM signal’s transmission over 100 km of standard fiber based on mid-span spectral inversion is experimentally demonstrated. The phase-conjugation is achieved by four-wave mixing in an optimized semiconductor optical amplifier (SOA), which solves the dispersion problem of the FSK/IM orthogonal signal. We use the DFB laser as the optical source, and take the Corning’s standard single-mode fiber as transmission link, and adopt the SOA with 500 μm length, and 0.15 optical confinement factor to realize spectral inversion. In the experiment, the central wavelength of orthogonal FSK/IM signal is fixed. We get the eye diagrams of the packet (label) in the IM (FSK) receiver. The results prove that the system has a good performance..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 608 (2009)
Demultiplexing from 160 Gb/s to 10 Gb/s Using Nonlinear Optical Loop Mirror
Yang Yanfu, Lou Caiyun, Zhao Xiaofan, Gao Yizhi, and Zhang Enyao
All-optical demultiplexing of 10-Gb/s base-rate channels out of 160 Gb/s optical time-division-multiplexed (OTDM) data streams is demonstrated. The demultiplexer in 160 Gb/s OTDM system utilizes a highly nonlinear optical loop mirror(NOLM). The relation of bit-error-rate (BER) of a demultiplexing versus walk-off and clAll-optical demultiplexing of 10-Gb/s base-rate channels out of 160 Gb/s optical time-division-multiplexed (OTDM) data streams is demonstrated. The demultiplexer in 160 Gb/s OTDM system utilizes a highly nonlinear optical loop mirror(NOLM). The relation of bit-error-rate (BER) of a demultiplexing versus walk-off and clock power at different timing jitter of date signals is calculated. The extinction ratio of demultiplexing window versus clock power at different walk-off is investigated. There is a proper clock power range, which can achieve the maximal extinetion ratio of demultiplexing and lower crosstalk of adjacent channels. Based on the developed ultra-short optical pulse source, the 160 Gb/s OTDM experimental system is demonstrated. For different signal powers, the extinction ratio changes little with signal power. When the data signal power is 7.3 dBm, the extinction ratio of window is over 23 dB. The time-division demultiplexing from 160 Gb/s to 10 Gb/s is achieved with error-free with nonlinear optical loop mirror structure including highly nonlinear fiber..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 611 (2009)
Analysis and Design of the Encoder/Decoder Based on Phase-Shifted Superstructured Fiber Bragg Grating
Ma Le, Yin Hongxi, and Zhu Lixin
The analysis theory of phase-shifted superstructured fiber Bragg grating (SSFBG) encoder/decoder is detailed, in the basis of transfer matrix method (TMM), and the design methodology of such the encoder/decoder is developed, which is validated by the simulation results of the 127-chip 2-phase and 4-phase encode/decoderThe analysis theory of phase-shifted superstructured fiber Bragg grating (SSFBG) encoder/decoder is detailed, in the basis of transfer matrix method (TMM), and the design methodology of such the encoder/decoder is developed, which is validated by the simulation results of the 127-chip 2-phase and 4-phase encode/decoder. The design methodology and results possesses guidance as well as reference value for the analysis of phase-shifted SSFBG. Meanwhile, the sensitivity difference between 4-phase family A code and 2-phase Gold code are also discussed, and the results reveal that the former codes require much higher precision of fabrication technology of gratings, than the latter ones under the scenario of the same code length..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 617 (2009)
Application of Optical Pulse Source with Frequency Chirp in OCDMA System
Fang Tao, Lu Lin, Li Yuquan, and Wang Hongchuan
Optical pulse source is one of the key techniques in optical code-division multiple access (OCDMA), and optical source affects the performance of the OCDMA system directly. The pulse chirp’s effect on performance of OCDMA temporal phase en/decoder is researched, and the feasibility of employing optical pulse source witOptical pulse source is one of the key techniques in optical code-division multiple access (OCDMA), and optical source affects the performance of the OCDMA system directly. The pulse chirp’s effect on performance of OCDMA temporal phase en/decoder is researched, and the feasibility of employing optical pulse source with frequency chirp in OCDMA is analyzed. Based on gain-switched distributed feedback (DFB) laser and equivalent phase-shifted superstructured fiber Bragg grating en/decoder, a 60 km OCDMA transmission at the rate of 2.5 Gb/s with bit error rate lower than 10-9 is experimentally demonstrated. The of theoretical analysis and experimental results indicate that the optical pulse source with frequency chirp can be applied in OCDMA system, which is significant for reducing the system cost and enhancing the practicality of OCDMA technology..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 623 (2009)
Pressure Sensor Based on Distributed-Bragg-Reflector Fiber Laser
Lan Yuwen, Liu Bo, and Luo Jianhua
A novel pressure sensor based on single-longitudinal-mode distributed Bragg reflector (DBR) was reported. DBR will induce birefringence under external press on the cavity. According to this, this laser can be used to sense external pressure by measuring the polarization mode beat-frequency shift. And as the beat-frequeA novel pressure sensor based on single-longitudinal-mode distributed Bragg reflector (DBR) was reported. DBR will induce birefringence under external press on the cavity. According to this, this laser can be used to sense external pressure by measuring the polarization mode beat-frequency shift. And as the beat-frequency ranges about 1 GHz, the demodulation is much easier to realize. Experiment proves that the beat-frequency ranges from 800 MHz to 1200 MHz when the pressure ranges from 0～1.2 N, and the degree of fitting is 99.76%. The sensor keeps the strong points of FBG sensing while its signal demodulation is quite convenient and exact..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 629 (2009)
Analysis on Amplifying Characteristic of Er3+/Yb3+ Co-Doped Microring Resonators
Wang Yuhai, Ma Chunsheng, Yan Xin, and Zhang Daming
For an Er3+/Yb3+ co-doped microring resonator, formulas of the transfer function and output power gain are presented, transmission characteristics are analyzed, and simulation is performed. Around the pumping wavelength of 0.98 μm and the central signal wavelength of 1.55 μm, the effects of the pump power, signal powerFor an Er3+/Yb3+ co-doped microring resonator, formulas of the transfer function and output power gain are presented, transmission characteristics are analyzed, and simulation is performed. Around the pumping wavelength of 0.98 μm and the central signal wavelength of 1.55 μm, the effects of the pump power, signal power, dopant concentration and amplitude coupling ratio on the output power gain are investigated, the transmission spectra are presented and the optimization of the device is carried out. Simulated results show that the output power gain of this device is much larger than those of the Er3+/Yb3+ co-doped straight waveguide amplifier with the same waveguide length. In the case of the pump power of 8 mW, signal power of 36.5 μW, Er3+ ion concentration of 1×1026 m-3, and Yb3+ ion concentration of 3×1027 m-3, the signal power gain of the device can reaches 11.6 dB and even 60 dB. Also, this device is propitious to the denser integration in the opto-electronic circuits..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 632 (2009)
Image Processing
Study on Enhancing Dynamic Range of CCD Image Based on Digital Micro-Mirror Device
Zhou Wang
A method based on digital micro-mirror device (DMD) as a SLM modulates an area array CCD is proposed. It is used to solve the information cossing caused by over exposed or under exposed, when shooting high-contrast sences by general CCD camera. A CCD is mapped as multi-districts and is destined for multi-times exposed A method based on digital micro-mirror device (DMD) as a SLM modulates an area array CCD is proposed. It is used to solve the information cossing caused by over exposed or under exposed, when shooting high-contrast sences by general CCD camera. A CCD is mapped as multi-districts and is destined for multi-times exposed through a pre-image. A CCD is able to be exposed partly as using a DMD. A data structure is designed for enhancing dynamic range of image from CCD. Experiments show that this method improves the photo quality, and shows information in high lights or shadows clearly. It also enhances the dynamic range of image data. The high quality photo and its high dynamic range data are obtained real-time without the software fuse many different exposure images..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 638 (2009)
Palmprint Recognition Based on Non-Negative Matrix Factorization and General Discriminant Analysis
Guo Jinyu, and Yuan Weiqi
Non-negative matrix factorization (NMF) has non-negative and local characteristics, and it is a new feature extraction method. NMF is an unsupervised learning method, and does not consider class information of samples applied to extract palmprint features, so the classification effect is not ideal. In order to fuse claNon-negative matrix factorization (NMF) has non-negative and local characteristics, and it is a new feature extraction method. NMF is an unsupervised learning method, and does not consider class information of samples applied to extract palmprint features, so the classification effect is not ideal. In order to fuse class information when the features of images are extracted, a palmprint recognition method based on non-negative matrix factorization and general discriminant analysis (GDA) is proposed. Before extracting features, the three-level wavelet transform is utilized to palmprint images to get the low-frequency sub-images. Then NMF and GDA are applied to extract palmprint features. The cosine distance between two feature vectors is calculated to match palmprint. The new algorithm is tested in PolyU plmprint database. The results show that compared with principal component analysis (PCA), independent component analysis (ICA) and NMF, the equal error rate (EER) of the new algorithm is the lowest as 0.16%, and the total time for feature extraction and matching is 0.812 s, so it meets the real-time system specification..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 643 (2009)
A Splicing Method of Sectioned Restoration Algorithm for Images with Space-Variant Point Spread Function
Tao Xiaoping, Feng Huajun, Lei Hua, Li Qi, and Xu Zhihai
A sectioned restoration algorithm for images with space-variant point spread function and the according splicing method are introduced. Firstly, the blurred image is divided to sub-frame sections based on isoplanatic region and extended outward region. Then, the sub-sections are restored by Lucy-Richard algorithm. AfteA sectioned restoration algorithm for images with space-variant point spread function and the according splicing method are introduced. Firstly, the blurred image is divided to sub-frame sections based on isoplanatic region and extended outward region. Then, the sub-sections are restored by Lucy-Richard algorithm. After removing the boundary regions which contain obvious ringing artifacts, the pixels in the rest of overlapping region between adjacent sections are weight stacked. The weight coefficients are related to the distances between the pixels and the boundary. At last, the sub-frames are spliced together to construct the composite full-image. The method is effective for eliminating the ringing artifacts coupled with sectioned image restoration with space-variant degraded function. It can be used in image restoration of remote-sensing with satellite and aerocraft, and also medical image processing..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 648 (2009)
Single-Band Infrared Image Colorization Algorithm Based on Color Transfer
Zhao Yuanmeng, Wang Lingxue, Jin Weiqi, Shi Shiming, and Wang Xia
Single-band infrared image colorization based on color transfer is studied, and a method of popping-out hot targets by applying pseudo-color coding is put forward. An appropriate reference image is selected, and its luminance channel is linearly transformed. Color of the image is transferred to single-band infrared imaSingle-band infrared image colorization based on color transfer is studied, and a method of popping-out hot targets by applying pseudo-color coding is put forward. An appropriate reference image is selected, and its luminance channel is linearly transformed. Color of the image is transferred to single-band infrared image based on decorrelated lαβ color space, through matching pixels between images using the mean and standard deviation in luminance channel over specified neighbor of pixels. The brightest parts of the resulted image are highlighted using the red hue of rainbow color coding, which usually associates with high temperature. By doing those to kinds of single-band infrared images, images with natural color appearance are obtained, which can avoid visual fatigue after long-time observation. And as the hot targets in the scene are made more noticeable, the target identification ability can be efficiently increased while the scene depth perception is remained..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 654 (2009)
Imaging Systems
Target Tracking Algorithm Based on Adaptive Template Update in Complex Background
Jia Guimin, Wang Xiangjun, and Zhang Shihai
A new adaptive template update strategy was proposed to increase the stability of target tracking in complex background. When the template matching fails similarity analysis between new target area and the template based on segmentation and correlation was applied to find the matching failure causes. A weighted functioA new adaptive template update strategy was proposed to increase the stability of target tracking in complex background. When the template matching fails similarity analysis between new target area and the template based on segmentation and correlation was applied to find the matching failure causes. A weighted function based on the distance of each pixel to the template center was put forward. And the normalized cross-correlation algorithm was improved to solve the occlusion issue. Experimental results indicate that the template can be modified adaptively. When the target is occluded or the target size is changed, the new algorithm is steadier compared with fixed template algorithm and each-frame template update algorithm..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 659 (2009)
Empirical Mode-Decomposition Method for Eliminating Extention of Zero Component in Fourier Transform Profilometry
Li Sikun, Chen Wenjing, Su Xianyu, and Xiang Liqun
In order to avoid frequency aliasing caused by the expansion of zero component in Fourier transform profilometry, empirical mode decomposition is introduced here, by which only one frame deformed fringe pattern is needed. The deformed fringe pattern is discomposed into a series of intrinsic mode functions, which vary fIn order to avoid frequency aliasing caused by the expansion of zero component in Fourier transform profilometry, empirical mode decomposition is introduced here, by which only one frame deformed fringe pattern is needed. The deformed fringe pattern is discomposed into a series of intrinsic mode functions, which vary form high frequency to low frequency by using empirical mode decomposition. So the high-frequency components are separated from the low ones. The zero component could be eliminated, which leads to the measurement range of FTP to be extended to nearly three times like using the π phase-shifting method. Experiments verify that it is an efficient method to extend the measurement range and keep the measurement speed..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 664 (2009)
Binary Spatio-Temporal Encoded Illumination for 3D Imaging
Li Yong, Chen Yunfu, Jin Hongzhen, and Wang Hui
An illumination method based on binary spatio-temporal encoding for 3D imaging is proposed. Every row of the projection plane is divided into some sections. The code of a section is encoded with the spatial and temporal coordinates of pixels in the section. During measurement, the codes of sections are retrieved by anaAn illumination method based on binary spatio-temporal encoding for 3D imaging is proposed. Every row of the projection plane is divided into some sections. The code of a section is encoded with the spatial and temporal coordinates of pixels in the section. During measurement, the codes of sections are retrieved by analyzing the captured image sequence. The adjacent codes with given number are assembled to form subsequences after all the codes of sections are recovered. The corresponding points between surface of scene, projection plane and camera image plane are worked out by matching subsequence in the designed sequence. Then, the shapes of objects are reconstructed with triangulation. The experimental results reveal that dense depth images can be obtained and texture can be acquired simultaneously without any additional images. The proposed method is robust and accurate..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 670 (2009)
Instrumentation, Measurement and Metrology
Measurement of Air-Space Thickness of Glan-Taylor Prisms
Wang Tao, Wu Fuquan, and Ma Lili
In order to measure the air-space thickness of Glan-Taylor prisms, effects of prisms on the single-mode Gaussian beam were analyzed. The result indicates that the transmitted beam light intensity shows periodical oscillation with change of incident angles on the prism’s end face. And the characteristics of the oscillatIn order to measure the air-space thickness of Glan-Taylor prisms, effects of prisms on the single-mode Gaussian beam were analyzed. The result indicates that the transmitted beam light intensity shows periodical oscillation with change of incident angles on the prism’s end face. And the characteristics of the oscillation is related to the incident light wavelength, beam intensity distribution, prism structure angle and air-gap thickness. For the incident single-mode Gaussian beam with given wavelength, the structure angle can be measured exactly before the prism is agglutinated, so the air-gap thickness can be measured by analyzing the characteristics of the oscillation. The experiment is designed, and the periodical oscillation characteristics are measured. Using the computer program, average relative deviation of the experimental oscillating period measured and the theoretical one was calculated by changing the air-space thickness in theoretical calculation with the interval of 0.0001 mm. For the sample prism, the minimum average relative error is 4.35%, and the air-space thickness is 0.0143 mm..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 676 (2009)
Analysis of 90° Off-Axis Parabolic Mirror Focal Spot Characteristic
Luo Xi, Chen Peifeng, and Wang Ying
With the wide application of off-axis parabolic mirror in laser processing, how to improve the quality of focal spot becomes a problem to be solved. In theory, the parabolic reflecting focusing approach can eliminate the influence of spherical aberration, and get high-quality focal spot. But the parabolic mirror is oneWith the wide application of off-axis parabolic mirror in laser processing, how to improve the quality of focal spot becomes a problem to be solved. In theory, the parabolic reflecting focusing approach can eliminate the influence of spherical aberration, and get high-quality focal spot. But the parabolic mirror is one of the most difficult adjustment reflector systems, and it is very sensitive to the optical axis misalignment. So that, the focal power density will decrease rapidly due to the tiny angular misalignment.In order to deepen understanding on the poor off-axis propertites of the parabolic mirror, by geometrical optics and physical optics, the influence of the misalignment angle on the 90° off-axis parabolic mirror focal spot characteristic is studied. The results indicate that the focal spot size is increased and the intensity is decreased greatly because of the tiny angular misalignment. By second-order moments, it is proved a pair of focal lines is produced near the focal plane due to the angular misalignment. It is also proved that the distances between the z planes at which the two focal lines are located and the focus F are equal, and are proportional to the misalignment angle.Because of the existence of the pair of focal lines, the incident Gaussian beam becomes elliptical Gaussian mode, which decreases the peak intensity at the focal plane. The parabolic mirror is very sensitive to the misalignment, and the misalignment angle of several mrad will make the peak intensity at the focal plane drop to the half..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 682 (2009)
Analysis and Correction of Retrace Error for Nonnull Aspheric Testing
Liu Dong, Yang Yongying, Tian Chao, Weng Junmiao, Zhuo Yongmo, and Yang Liming
Nonnull test is often adopted in optical metrology for aspheric testing. But due to its violation of null condition, the obtained surface figure would be different from that of the real, which is called retrace error accordingly. Retrace error of nonnull aspheric testing is analyzed in detail with conclusions that retrNonnull test is often adopted in optical metrology for aspheric testing. But due to its violation of null condition, the obtained surface figure would be different from that of the real, which is called retrace error accordingly. Retrace error of nonnull aspheric testing is analyzed in detail with conclusions that retrace error has much to do with the aperture, relative aperture and surface shape error of the apsheric under test. Correcting methods are proposed according to the manner of the retrace errors. Both of computer simulation and experimental results show that the proposed methods can correct the retrace error effectively. The analysis and proposed correction methods bring much to the application of nonnull aspheric testing..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 688 (2009)
Experimental Research on Surface Roughness Measurement Using Angular-Speckle Correlation
Liu Hengbiao, and Liu Chenglin
The surface roughness measurement is experimentally researched by using angular-speckle correlation method on blasted sand surface. Through the data processing and analysis of laser speckle patterns, moving correlation algorithm was presented to get the maximal angular-speckle correlation coefficients. This method can The surface roughness measurement is experimentally researched by using angular-speckle correlation method on blasted sand surface. Through the data processing and analysis of laser speckle patterns, moving correlation algorithm was presented to get the maximal angular-speckle correlation coefficients. This method can avoid the negative effects of surface flatness and waviness effectively. Under the prime measurement condition, the optimal incident angle increment of laser beam was given, and a method of surface roughness measurement including speckle pattern acquisition and processing was developed. The key of this method is that far-field speckle patterns in different incident angles and illumination areas of rough surface are detected and processed. The experimental results indicate that prime root-mean-square (RMS) deviation measured by this method is almost linear with the arithmetical mean deviation of the surface-samples..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 697 (2009)
Dual-Grating-Based Nanometer Measurement
Zhou Shaolin, Yang Yong, Chen Wangfu, Yan Wei, Ma Ping, Jiang Wenbo, Hu Song, and Tang Xiaoping
In order to measure the variation of displacement or gap of two parallel planes in nanometer level, a grating-based metrology was brought forward and researched. Two superposed micro-gratings with slightly different periods were adopted to generate a set of periodic moiré fringes, the period of which was hugely maIn order to measure the variation of displacement or gap of two parallel planes in nanometer level, a grating-based metrology was brought forward and researched. Two superposed micro-gratings with slightly different periods were adopted to generate a set of periodic moiré fringes, the period of which was hugely magnified with regard to that of two gratings. And the relative displacement of gratings was encoded in the phase of fringes. Firstly, an approximate theoretical model about distribution of complex amplitude of fringes of two gratings was built. Then, a method of measuring in-plane displacement and gap of two parallel planes was designed on the basis of this model. Finally, numerical computation about the process of movement of two gratings to generate corresponding fringes was performed. The results show that a small relative displacement of two gratings leads to a large displacement of corresponding fringes and this method can resolve the variation of displacement or gap of two parallel planes within nanometer..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 702 (2009)
Model of Polarized Thermal Emission from Rough Metal Surface
Wang Zhen
The model of thermal infrared polarization properties of the metal surface was discussed. The statistic properties were considered in this model as well the surface shadowing effect.The relation between thermal infrared polariztion and irradiation angle is simulated for different surface roughness. The simulation resulThe model of thermal infrared polarization properties of the metal surface was discussed. The statistic properties were considered in this model as well the surface shadowing effect.The relation between thermal infrared polariztion and irradiation angle is simulated for different surface roughness. The simulation results of smooth metal surface with roughness of 1.6 μm accord with the experimental data very well, but the simulation results of rough metal surface with roughness of 6.8 μm disaccord with the experimental data. After the shadowing effect of the rough metal surface is considered, the simulation results is improued greathy. The main related factors to determine the thermal polarization properties of the metal surface were discussed..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 707 (2009)
Establishment of Customized Shoe Last Expert System Based on Light Sectioning Method
Shi Hui, Wang Boxiong, Jia Qianqian, and Luo Xiuzhi
To make customised sports shoes, a customized shoe last expert system is established based on the light sectioning method for 3D profile measurement. A least square fitting method is proposed to approximate the scanned cloud data, to establish the parameterized standard shoe last database in form of NURBS curves. A fooTo make customised sports shoes, a customized shoe last expert system is established based on the light sectioning method for 3D profile measurement. A least square fitting method is proposed to approximate the scanned cloud data, to establish the parameterized standard shoe last database in form of NURBS curves. A foot shape subsectioning method based on the shape feature points is used to establish the segmental empirical repository of shoe last conformability by using the generative formula. The expert system is therefore formed with the standard shoe last database and the segmental empirical repository. With the expert system, special shoe last is customizod, and the system can spread to other kinds of shoes..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 712 (2009)
Measurement of Ultra-Low Loss Mirrors by Cavity Ring-Down Technique with Laser Frequency Sweeping
Li Zhigang, Zhang Yuchi, Zhang Pengfei, Li Yuan, Li Gang, Wang Junmin, and Zhang Tiancai
Ultra-low loss mirror (super-mirror) is an important optical element for high-quality optical cavity and optical sensitive measurements in many fields, and the measurement of mirror losses on 10-6 level is an important issue. We have effectively mode-matched the incident beam to the TEM00 mode of cavity by scanning cavUltra-low loss mirror (super-mirror) is an important optical element for high-quality optical cavity and optical sensitive measurements in many fields, and the measurement of mirror losses on 10-6 level is an important issue. We have effectively mode-matched the incident beam to the TEM00 mode of cavity by scanning cavity length and sweeping laser frequency near the TEM00 mode of cavity. An optical switch triggered by a hysteresis comparator was employed to cut off the incident laser beam and the cavity ring-down (CRD) signal was obtained. We have measured a batch of super-mirror with losses on 10-6 level. The precision of this system is better than 10-6, and the highest reflectivity is (99.99914±0.00004)% . The results indicate that the losses of super-mirrors are diverse even if the super-mirrors are from the same batch and stored in the same environment..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 718 (2009)
Locating Error Analysis in Pipeline Leakage Detection and Prewarning System Based on Modeling Using Jones Matrix
Feng Hao, Jin Shijiu, Zeng Zhoumo, Zhou Yan, and Qu Zhigang
To eliminate the gross error in the distributed optical fiber pipeline leakage detecting andprewarning system and to improve the locating accuracy, based on the analysis on the detecting and locating principle, the optical polarization model is established which is based on the equivalent Jones matrix of the single-modTo eliminate the gross error in the distributed optical fiber pipeline leakage detecting andprewarning system and to improve the locating accuracy, based on the analysis on the detecting and locating principle, the optical polarization model is established which is based on the equivalent Jones matrix of the single-mode optical fiber birefringence. Model simulation shows that the cause for the gross error is the discrepancy of two signals, which means that the signals acquired by the photodetectors from the same vibroseis are not correlative. According to the theoretical model, the solution of using external polarization controller to change the polarization direction is put forward. It is proved by the experiment that the solution can solve the problem preferably and improve locating accuracy. Furthermore, a theoretical guidance of the system improvement and the adjustment in optical structure is provided based on the theoretical model..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 723 (2009)
Phase-Synchronization Using Double Optical-Path Technology in Fiber Optic Gas Sensors
Li Zhengying, Wang Honghai, Chen Songlin, Zhao Lei, and Yu Xin
The second harmonic is used when using wavelength modulation technology to design gas sensor based on optical spectrum. Whereas phase difference between gas sensing signal and double frequency reference signal has great influence on the measured result of second harmonic. A reference optic fiber is used to synchronize The second harmonic is used when using wavelength modulation technology to design gas sensor based on optical spectrum. Whereas phase difference between gas sensing signal and double frequency reference signal has great influence on the measured result of second harmonic. A reference optic fiber is used to synchronize the phases. There are two parts in this technology: phase shift circuit and reference optic fiber. Phase shift circuit consists of digital circuit which is used to compensate circuit delay and is easy to modulate. Reference optic fiber which does not pass by gas cell is added in the optical path. It makes sure that the phases between measured signals and referenced signals are synchronized no matter how the length of the optic fibers changes. In the design of phase synchronization using double optical path based on wavelength modulation,the error of meausred result keeps lower than ±10% with phase of measured signals changing from 0° to 90°. It not only simplifies the calibration of the sensor, but also makes possible to install the sensor at any distance site..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 728 (2009)
An Improved Stoilov Algorithm Based on Statistical Approach
Xu Xingfen, and Cao Yiping
Stoilov algorithm is a recently developed equivalent step algorithm whose phase step is arbitrary. The value of the phase shifting needn’t be known but phase step must remain invariable. The wrap phase caused by measured object can be derived correctly. So it is paid wide attention in three-dimensional measurement fielStoilov algorithm is a recently developed equivalent step algorithm whose phase step is arbitrary. The value of the phase shifting needn’t be known but phase step must remain invariable. The wrap phase caused by measured object can be derived correctly. So it is paid wide attention in three-dimensional measurement field. However, Stoilov algorithm excessively depends on the intensity of the image, and subtraction, division and extraction must be operated in its mathematical model. Imaging process will cause some abnormal phenomena somewhere such as the zeroth denominator and complex phase, which lead to the incorrect phase calculation or incorrect phase unwrapping. The reconstructed object will be misshapen or anamorphic, or even the measured object can’t be reconstructed. So a new method based on the statistical approach to improve Stoilov algorithm has been proposed. By this method the phase error brought by the abnormal phenomena is restrained and the precision of three-dimensional measurement is improved. Experiments show its feasibility and validity..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 733 (2009)
Lasers and Laser Optics
Laser Diode-Pumped Self-Mode-Locking Laser with a Self Q-Switched Cr4+∶Nd3+∶YAG Laser
Zhang Haikun, Chen Xiufeng, Wang Peiji, Zhang Zhongshi, Zhao Shengzhi, Yang Kejian, and Xiang Fangchao
Simultaneous self-mode-locking and self-Q-switching in a laser diode-pumped Cr4+∶Nd3+∶YAG laser is presented. More than 80% modulation depth of self-mode-locking has been achieved at the threshold pump power. A maximum average output power of 233 mW was generated at the maximum incident pump power of 5.72 W, correspondSimultaneous self-mode-locking and self-Q-switching in a laser diode-pumped Cr4+∶Nd3+∶YAG laser is presented. More than 80% modulation depth of self-mode-locking has been achieved at the threshold pump power. A maximum average output power of 233 mW was generated at the maximum incident pump power of 5.72 W, corresponding to a maximum pulse energy of 16.5 μJ for a single self-Q-switched pulse. The typical Q-switched envelope duration containing the mode-locked pulse trains was found to be around 120 ns and the repetition rate for the self-mode-locked pulse trains within the self-Q-switched pulse envelope was about 357 MHz. The width of the self-mode-locked pulse was estimated to be less than 560 ps. Using a hyperbolic secant function method, we introduced a rate equation model not only considering the Gaussian distribution of the intracavity photon density and the influences of the continuous pump rate, but taking into account the stimulated radiation lifetime of the active medium as well as the excited-state lifetime of the saturable absorber. Numerically solving the set of equation, the theoretical calculations are in good agreement with the experimental results..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 738 (2009)
Emission of Low-Dimensional Structures Formed by Femtosecond Laser Interaction with Semiconductor
Zhang Rongtao, Xu Li, and Wu Keyue
The interaction of ultra-short pulses (120 fs) of laser radiation (800 nm) with Si and SiGe samples was analyzed. Some kinds of low-dimensional structures were found. An ablation model was proposed to explain the effect. It has been noticed that a grating shape in 400 nm period scale occurs on surface of silicon. It isThe interaction of ultra-short pulses (120 fs) of laser radiation (800 nm) with Si and SiGe samples was analyzed. Some kinds of low-dimensional structures were found. An ablation model was proposed to explain the effect. It has been noticed that a grating shape in 400 nm period scale occurs on surface of silicon. It is found that the grating of one-dimensional structure has an intensive photoluminescene (PL) whose peak is at wavelength 719 nm. The PL peak is smaller, and its mechanism is analyzed from the pulse width and repetitive rate of laser. When the irradiation energy on silicon increases to exceed the ablation threshold for the grating shape to be broken and a kind of sharp conical structure begins to set up. Controlling preparing condition, a high-quality nano-grating can be made on silicon base for diffracting and micro-splitting of beam..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 743 (2009)
High Sensitivity CW-Cavity Ring Down Spectroscopy of Tuning Wavelength
Tan Zhongqi, Long Xingwu, and Huang Yun
A high-sensitivity system of CW-cavity ring down spectroscopy is built with a distributed-feedback diode laser as light source. In which, the incident laser is in resonances with the mode of passive optical cavity via tuning the diode laser′s wavelength, and the switching off of laser is carried via modulating the diodA high-sensitivity system of CW-cavity ring down spectroscopy is built with a distributed-feedback diode laser as light source. In which, the incident laser is in resonances with the mode of passive optical cavity via tuning the diode laser′s wavelength, and the switching off of laser is carried via modulating the diode laser′s current. The CW-CRDS system with and without etaloning effects is measured, and experiment shows that theirnoise-equivalent detection sensitivity is 2.56×10-7 cm-1 and 1.27×10-8 cm-1 respectively. The N2 broadening halfwidth of N2O molecule at 6591.43 cm-1 is measured with the longitudinal mode spacing of cavity as step of wavelength scanning, the measured half-width at half-maximum of line is 0.0819 cm-1, and 0.0808 cm-1, then the different between measurement value and HITRAN2004 database is discussed..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 747 (2009)
Ultrafast Carrier Dynamics in Surface of Silicon-on-Insulator
Liu Guodong, Wang Guibing, Li Jianfeng, Fu Bo, and Luo Fu
Time-resolved reflectivity changes of silicon-on-insulator (SOI) with different crystalline silicon film thicknesses have been measured using the femtosecond (λ=800 nm) pump-probe technique to investigate the ultrafast carrier dynamics. The underlying physics of carrier diffusion and recombination processes is discusseTime-resolved reflectivity changes of silicon-on-insulator (SOI) with different crystalline silicon film thicknesses have been measured using the femtosecond (λ=800 nm) pump-probe technique to investigate the ultrafast carrier dynamics. The underlying physics of carrier diffusion and recombination processes is discussed using the reflectivity model, which is based on the time evolution of photoexcited carrier density and temperature. The research shows that, the contribution of surface recombination velocity (SRV) dominates the response of excited carrier dynamics, and the SRV increases with thickness of silicon thin films decreasing. The corresponding active surface state density can reach 1015 cm-2. For relatively small SRV, the transient reflectivity changes are dominated by the ultrafast response of photoexcited carriers. But the contribution of lattice temperature appears to be more significant with large SRVs, which causes the reflectivity to recover and surpass the initial value in shorter time..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 752 (2009)
Research on High-Power Laser Induced Damage of Large Aperture Fused Silica
Tang Shunxing, Ouyang Xiaoping, Zhu Baoqiang, and Lin Zunqi
Damage of a sampling fused silica reflector has been observed when the performance of the 9th beam of Shenguang-Ⅱ was tested. By analyzing the inducement and mechanism,it is confirmed that the transverse stimulated Brillouin scattering (TSBS) induces the damage.Increasing the bandwidth by 30 GHz can prevent further damDamage of a sampling fused silica reflector has been observed when the performance of the 9th beam of Shenguang-Ⅱ was tested. By analyzing the inducement and mechanism,it is confirmed that the transverse stimulated Brillouin scattering (TSBS) induces the damage.Increasing the bandwidth by 30 GHz can prevent further damage efficiently.A propagation model of TSBS in large aperture fused silica has been established,which can calculate the intensity threshold of laser induced damage in fused silica. Theoretical calculation and experimental results show that the fused silica glass will be damaged if the energy of large aperture(310 mm diameter) narrow bandwidth laser reaches 2～3 kJ..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 756 (2009)
Tuning Characteristic of PPLN Based Difference-Frequency-Generation Laser System
Chen Dong, Liu Wenqing, and Zhang Yujun
The room-temperature continuous-wave tunable narrow band coherent light source in the mid-infrared region is valuable for trace gas sensing. Nonlinear optical difference-frequency generation (DFG) scheme has been used as a useful way to meet the requirement, and complementarity for traditional laser technology. The temThe room-temperature continuous-wave tunable narrow band coherent light source in the mid-infrared region is valuable for trace gas sensing. Nonlinear optical difference-frequency generation (DFG) scheme has been used as a useful way to meet the requirement, and complementarity for traditional laser technology. The temperature and signal light wavelength tuning characteristics of quasi-phasematching (QPM) based DFG system were theoretically studied, the analytical expressions of temperature and signal light wavelength tuning bandwidths of periodically poled LiNbO3(PPLN) were deduced based on the general theory of QPM. A widely tunable room-temperature mid-infrared laser source system based on QPM in PPLN crystal has been developed, and the mid-infrared coherent radiation is produced from 3.2 to 3.7 μm with a maximum output power of about 1 μW. The temperature and signal wavelength tuning characteristics of the system were experimentally studied, and the experimental results were compared and analyzed with the theory..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 761 (2009)
Materials
Effect of Polarization of Ar+ Laser Beams on Surface-Relief-Grating Formation Behavior of Molecular Azo Glass
Guo Miaocai, Xu Zeda, and Wang Xiaogong
Formation of surface-relief-gratings (SRGs) on amorphous azo glass films (IAC-4) was studied by using two interfering Ar+ laser beams with p+p, p+s and RCP+LCP polarizations to inscribe the gratings. The diffraction efficiencies and the surface modulation of SRGs are measured by real time grating diffraction efficiencyFormation of surface-relief-gratings (SRGs) on amorphous azo glass films (IAC-4) was studied by using two interfering Ar+ laser beams with p+p, p+s and RCP+LCP polarizations to inscribe the gratings. The diffraction efficiencies and the surface modulation of SRGs are measured by real time grating diffraction efficiency detection method and atomic force microscope, which strongly depend on the polarizations of the writing beams and show an order of RCP+LCP>p+s>p+p. SRGs can be rapidly inscribed on IAC-4 films with large surface modulations and high diffraction efficiencies when irradiated with RCP+LCP interfering beams. But the inscription was quite inefficient using p+p interfering beams. When irradiated with p+s polarization beams, formation of half-period gratings was observed. After irradiated with p+p, p+s or RCP+LCP interfering beams (58 mW/cm2 per beam) for 80 s～2 min, the diffraction efficiencies and modulated depths of the photo-induced SRGs are 3.1% and 23 nm, 9.3% and 120 nm, 62% and 734 nm respectively. The results indicate that IAC-4 can be used as a competitive material for SRG applications, but the fabrication heavily relies on the light polarization conditions..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 767 (2009)
Investigation of Self-Diffraction Effect in C60-Doped Nematic Liquid Crystals Induced by Gaussian Beam
Ren Changyu, Sun Xiudong, Liu Zhengjun, and Pei Yanbo
Based on the Kirchhoff-Fraunhofer diffraction integral, a theoretical study, with reference to experimental results, of transverse self-phase modulation effects in the transmission of a laser beam through a homeotropic C60-doped nematic liquid crystal (5CB) cell was presented. Two different type of concentric diffractiBased on the Kirchhoff-Fraunhofer diffraction integral, a theoretical study, with reference to experimental results, of transverse self-phase modulation effects in the transmission of a laser beam through a homeotropic C60-doped nematic liquid crystal (5CB) cell was presented. Two different type of concentric diffraction rings were observed in the far field. The simulation results show that, the diffraction rings were determined by the two factors of C1 and C2. When the sign of C1 is identical to that of the C2, the pattern in the far field is a series of thin, narrow diffraction rings with a central bright spot. When the sign of C1 is opposite to that of the C2, the thick diffraction ring pattern with central dark spot and the large distribution range will emerge in the far-field plane. The phenomenon is attributed to the spatial self-phase modulation caused by the refractive index change of the medium when the Gaussian beam passes through the sample. The results show that the theoretical analysis is consistent with the observed experimental phenomena, which is significant in the applications of practical nonlinear optical limiters for the eye or sensor protection..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 772 (2009)
Beam Splitter and Deflector in Two-Dimensional Photonic Crystals
Kong Weijin, Yun Maojin, Wang Mei, and Shan Fukai
The self-collimation effect of TM mode in a two-dimensional square lattice photonic crystal is studied by using plane-wave expansion method, and two-dimensional finite-difference time-domain method with perfectly matched layer absorbing boundary conditions for the application of beam adjustment and deflection. The lighThe self-collimation effect of TM mode in a two-dimensional square lattice photonic crystal is studied by using plane-wave expansion method, and two-dimensional finite-difference time-domain method with perfectly matched layer absorbing boundary conditions for the application of beam adjustment and deflection. The light transmission through the two-dimensional square lattice photonic crystal is investigated in detail with its equal-frequency contours plot and band structure, based on self-collimation effect and band gap in two-dimensional photonic crystals. The simulation results show that one-to-two beam splitter, deflector and one-to-three beam splitter can be realized by appropriately arranging the line defect along the proper direction. The energy of the transmitted beam and the deflected beam versus the radius of the line defect along ΓX direction is discussed. Such devices can greatly expand the application of photonic crystals in high-density optical integrated circuits..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 818 (2009)
Medical Optics and Biotechnology
Biological Effects of Laser Polarization on Platymonas Subcordiformis
Lei Jinping, Chen Weiwei, Chen Rong, Ou Lin, Wang Lijiang, Cai Changmei, and Li Zuanfang
In this paper, the purpose is to study the biological effects of platymonas subcordiformis irradiated by polarization and non-polarized laser, such as promoting, pigment chlorophyll content and absorption spectra of pigment extracts. The platymonas subcordiformis were irradiated by the argon laser at 488 nm, 70 mW outpIn this paper, the purpose is to study the biological effects of platymonas subcordiformis irradiated by polarization and non-polarized laser, such as promoting, pigment chlorophyll content and absorption spectra of pigment extracts. The platymonas subcordiformis were irradiated by the argon laser at 488 nm, 70 mW output power. The number of algae cells were counted by sampling in two days interval, and after culturing six days, the chlorophyll was extracted and its content to be detected and the absorption spectrum of chlorophyll to be scanning. The result showed that, for the platymonas subcordiformis irradiated by polarization and non-polarized laser, the effect of growth promoting was not clear distinction, the cumulative of chlorophyll content was not different, and the absorption spectrum of pigment extracts did not vary also. On our reseach conditions, whether the laser on polarization or not are all the effective role of biological effects of platymonas subcordiformis. The relation of laser polarization and laser biological effects is to be further studied..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 778 (2009)
Nonlinear Optics
Elliptical Polarized Single-Cycle THz Pulse Generated by Femtosecond Laser Filamentation in Air
Zhang Yizhu, Chen Yanping, Li Zhiqiang, Xu Shengqi, Liu Weiwei, and See Leang Chin
Strong forward propagated THz pulse can be generated by femtosecond laser filamentation in air. An electro-optical sampling based time domain spectroscopy (TDS) technique is used to diagnose the THz pulse produced by a femtosecond laser filament in air. The filament is generated by a 1 mJ, 50 fs laser pulse centered atStrong forward propagated THz pulse can be generated by femtosecond laser filamentation in air. An electro-optical sampling based time domain spectroscopy (TDS) technique is used to diagnose the THz pulse produced by a femtosecond laser filament in air. The filament is generated by a 1 mJ, 50 fs laser pulse centered at 800 nm. The THz pulse measured in experiment is a single-cycle pulse (pulse width is 1ps) and the corresponding spectrum peak value is around 1 THz. The polarization orieatation of pump beam is rotated and the variation of electro-optical sampling signal is analyzed-Compared the experimental results with the calculational results, the polarization of THz pulse emitted from filamentation is elliptical..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 781 (2009)
Small-Scale Self-Focusing of Divergent Beams in Gain Medium
Zhang Yanli, Li Xiaoyan, and Zhu Jianqiang
Bespalov-Talanov theory is extended to the divergent beam in gain medium. The small-scale self-focusing properties are studied systematically in small-signal and saturated gain conditions. In the case of small-signal gain, for a given input power with different initial radiuses, the cutoff spatial frequency, the fastesBespalov-Talanov theory is extended to the divergent beam in gain medium. The small-scale self-focusing properties are studied systematically in small-signal and saturated gain conditions. In the case of small-signal gain, for a given input power with different initial radiuses, the cutoff spatial frequency, the fastest growing frequency and the maximum growth of small-scale modulation, evolve differently with the change of the small-signal gain and propagation distance. The initial radius represents the degree of diffraction divergence, the decrease of the initial radius can reduce the fastest growing frequency and the maximum perturbation growth. For a given output power, the increase of the small-signal gain can decrease the maximum perturbation growth, while the fastest growing frequency shifts to the lower frequency. Compared with the small-signal gain, the fastest growing frequency and the maximum gain are smaller in medium with saturated gain. In different system design, the amplifier gain and the beam parameters should be weighed and selected properly in practical systems..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 786 (2009)
Optical Devices
Improving the Profiles of Imaging Patterns by Optimizing Mask in DMD-Based Maskless Photolithography
Guo Xiaowei, Du Jinglei, and Liu Yongzhi
In recent years, DMD-based maskless lithography, as a tool for IC mask and microstructure fabrication, has attracted wide attention. It employs a computer-controlled DMD as a switchable projection mask and binary pulse-width modulation to generate grayscale. However, the surfaces of the imaging objects will deviate froIn recent years, DMD-based maskless lithography, as a tool for IC mask and microstructure fabrication, has attracted wide attention. It employs a computer-controlled DMD as a switchable projection mask and binary pulse-width modulation to generate grayscale. However, the surfaces of the imaging objects will deviate from the designed and produce ruled surges when the tool is used for fabricating microstructures with continuous surface relief. The physical mechanism of the surges was firstly explored, and then simulated annealing algorithm was adopted for removing surface surges. The simulation results show that the imaging quality after optimization is clearly better than that before optimization and the surges were mostly removed in the 5% range of relative exposure deviation. Finally, the axicon lens array with good surface quality was fabricated by using the optimized mask. The method is simple and provides a new way to improve the imaging quality in DMD-based maskless lithography, which is very useful for the fabrication of high-performance microstructure device..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 794 (2009)
Analysis of Rayleigh Backscattering Noise in Micro-Optical Resonance Gyroscope
Yu Huaiyong, Zhang Chunxi, Feng Lishuang, Hong Lingfei, and Xing Jiwu
The theory of Rayleigh backscattering noise in the silicon substrate micro-optical resonance gyro (MORG) is described, and the static-and dynamic-state models of MORG are constructed. Characteristics of this noise in the resonator of SiO2 on Si substrate are formulized. The relationship between the Rayleigh backscatterThe theory of Rayleigh backscattering noise in the silicon substrate micro-optical resonance gyro (MORG) is described, and the static-and dynamic-state models of MORG are constructed. Characteristics of this noise in the resonator of SiO2 on Si substrate are formulized. The relationship between the Rayleigh backscattering noise and main signal intensity, and the effect on the main signal by the interference signal of the noise and reverse optical signal, are simulated by software algorithm. Effect of this noise on the performance of the resonator,such as the definition and the maximal sensitivity, is analyzed. The scheme to suppress the noise is proposed. Based on the anslysis, the experimental system is set up. The results agree well with theoretic calculation..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 799 (2009)
Analysis of Thermal Spreading Boards for High-Power AlGaInP Red LEDs
Chen Huanting, Lü Yijun, Chen Zhong, Zhang Haibing, and Gao Yulin
The thermal characteristics of three kinds of thermal spreading boards with high-power AlGaInP LEDs were analyzed by finite volume thermal simulation method,transient thermal resistence measurement and the relationship of heat sink temperature and peak wavelength. With the same type and configuration of AlGaInP LEDs onThe thermal characteristics of three kinds of thermal spreading boards with high-power AlGaInP LEDs were analyzed by finite volume thermal simulation method,transient thermal resistence measurement and the relationship of heat sink temperature and peak wavelength. With the same type and configuration of AlGaInP LEDs on the three kinds of thermal spreading boards, the difference lies in thermal spreading channels and materials. Transient temperature response curve is measured from which structure functions are extracted to evaluate the thermal resistance and the thermal capacitance in the heat flow path. Based on the structure function, thermal problem during the heat flow path can be easily located. The electroluminescence spectra of AlGaInP LEDs with different thermal spreading boards under various electrical currents were investigated. In terms of the relationship of heat sink temperature-peak wavelength, the thermal characteristics of samples can be qualitatively estimated. By comparison, thermal simulation and testing offer important evidence for the optimization and design of the most suitable thermal spreading model for ceramic boards..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 805 (2009)
Removing Characteristics of Ultraprecise Bonnet Polishing on Spatial Optics Elements
Li Hongyu, Zhang Wei, and Yu Guoyu
Theoretical and experimental research on removing characteristics of ultraprecise bonnet polishing methods are made to get an ultra-smooth surface for optical elements. A material removing model of bonnet polishing processional motion is established according to kinematic principle based on Preston equation. The model Theoretical and experimental research on removing characteristics of ultraprecise bonnet polishing methods are made to get an ultra-smooth surface for optical elements. A material removing model of bonnet polishing processional motion is established according to kinematic principle based on Preston equation. The model is modified in terms of Hertz contact theory using the physical characteristics of polishing bonnet tools. The affect of several main technological parameters to removing characteristics of processional polishing motion is analyzed by means of computer simulation, and an orthogonal test is made on an ultraprecise numerical control polishing machine. The simulation results fit well with test results and four important conclusions on bonnet polishing technology are obtained. The span of processional angle and decrement is provided and an ultraprecise smooth surface with RMS=0.024 λ figure precision is achieved, which provides theoretical foundation to research on bonnet polishing technology of optical elements..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 811 (2009)
Quantum Optics
Double-Layer Optical-Trap Arrays for Trapping Cold Atoms or Molecules
Mu Renwang, Ji Xianming, and Yin Jianping
A novel scheme of double-layer optical trap, which is composed of binary π-phase-plate arrays and focusing lens arrays, for trapping cold atoms or molecules was proposed. The double-layer optical trap is formed at the two sides of the focal plane when this optical system is illuminated by plane light wave. The principlA novel scheme of double-layer optical trap, which is composed of binary π-phase-plate arrays and focusing lens arrays, for trapping cold atoms or molecules was proposed. The double-layer optical trap is formed at the two sides of the focal plane when this optical system is illuminated by plane light wave. The principles of producing the double-layer optical trap were introduced and the relations between intensity distribution as well as intensity gradient and parameters of the optical system were analyzed in detail. Moreover, the optical dipole potential and spontaneous scattering speed, including Rayleigh scattering and Raman scattering, of the atoms or molecules trapped by double-layer optical trap were studied. The scheme can be used not only in trapping atoms or molecules of multiple samples and all optical Bose-Einstein condensation (BEC),but also in preparing novel double-layer 2D optical crystal lattice..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 822 (2009)
Separability Condition for Multi-Mode Continuous-Variable Systems
Pu Zhongsheng, Du Xiaofang, Gao Jianlong, and Guan Qiuyun
A separability condition based on the product variance of a pair of Einstein-Podolsky-Rosen (EPR) type operators is obtained for continuous-variable systems by using Heisenberg uncertainty relation and Cauchy-Schwarz inequality. It can be used to detect the entanglement of non-Gaussian states, the entanglement of coherA separability condition based on the product variance of a pair of Einstein-Podolsky-Rosen (EPR) type operators is obtained for continuous-variable systems by using Heisenberg uncertainty relation and Cauchy-Schwarz inequality. It can be used to detect the entanglement of non-Gaussian states, the entanglement of coherent state. Moreover, anther condition used to judge if quantum state gets entangled is obtained by using total variance. Two conditions were discussed contrastively were j was position operator, j was momentum operator and n=2. The result shows that detection ability of the former inequality is stronger than the latter when the coefficient is satisfied with the relatin of ∑｜cjdj｜＞4..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 827 (2009)
Spectroscopy
Cavity-Enhanced Absorption Spectroscopy Based on Diode Laser
Pei Shixin, Cui Fenping, Zhan Yu, and Li Chuanqi
A cavity-enhanced absorption spectroscopy (CEAS) system has been build up, in the system, a tunable near-infrared DFB diode laser is used as the light source, and an optical cavity which is consisted of two mirrors with reflectivity of 99.7% is used as the absorption cell. Based on the working condition of the diode laA cavity-enhanced absorption spectroscopy (CEAS) system has been build up, in the system, a tunable near-infrared DFB diode laser is used as the light source, and an optical cavity which is consisted of two mirrors with reflectivity of 99.7% is used as the absorption cell. Based on the working condition of the diode laser and optical cavity, the technology of CEAS is divided into three kinds: control wavelength CEAS, control cavity length CEAS and both scan wavelength & cavity length CEAS. Carbon dioxide (CO2) and methane (CH4) is used as the main sample gas, control wavelength CEAS and control cavity length CEAS are used to get the absorption spectroscopy of CO2 near the region of 1.573 μm; both scan wavelength & cavity length CEAS are used to get the absorption spectroscopy of CH4 near the region of 1.316 μm, the sensivity and the quantitative analytical ability of the three CEAS is also studied. It demonstrates that CEAS is a quantitative absorption spectroscopy technologic with the advantage of simple setup, easy operation, high sensivity and good stability; the sensivity of both scan wavelength and cavity length CEAS is superior to 1.15×10-7 cm-1..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 831 (2009)
Method for Terahertz Time-Domain Spectral Analysis Based on Wavelet Transform
Yu Qian, Zhao Yuejin, Yu Fei, Liu Xiaohua, Zhang Liangliang, and Dong Liquan
The conventional terahertz spectral analysis based on Fourier transform needs to measure the terahertz reference signal without simples, and the terahertz spectra measurement is required in nitrogen. A novel method for terahertz time-domain spectral analysis based on wavelet transform is proposed to reduce terahertz spThe conventional terahertz spectral analysis based on Fourier transform needs to measure the terahertz reference signal without simples, and the terahertz spectra measurement is required in nitrogen. A novel method for terahertz time-domain spectral analysis based on wavelet transform is proposed to reduce terahertz spectral measurement steps. Firstly, the de-noising process about the spectroscopic data of the sample is achieved, and then the multi-scale wavelet-transform is realized by Coiflets wavelet base. The wavelet multi resolution entropies of samples under different wavelet decomposition scales are calculated, and the characteristic information describing samples is obtained directly. The experimental results indicate that the wavelet multi-resolution entropies, which are observably different between different samples but adequately stable between the same samples, can provide a valid quantitative criterion for the materials recognition. Spectral signal′s wavelet multi-resolution entropies have good repetition in different humidity, and the average variance of the wavelet multi-resolution entropies is smaller than 0.05..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 838 (2009)
Feature Extraction Based on Multifractal Spectrum for Hyperspectral Data
Liu Xiaogang, Zhao Huijie, and Li Na
Considering the fractal dimension deficiency to process hyperspectral data, a singularity feature extraction method was proposed, and the multifractal spectrum was used to characterize the singularity feature of spectra. In this method, the spectral curves were divided to several segments according to fractal measure, Considering the fractal dimension deficiency to process hyperspectral data, a singularity feature extraction method was proposed, and the multifractal spectrum was used to characterize the singularity feature of spectra. In this method, the spectral curves were divided to several segments according to fractal measure, and the partition function was generated with the spectral probability measure. The multifractal spectrum was extracted with the Legendre transformation of scale exponent. Effective features of multifractal spectrum were selected based on discriminable rule of Bhattacharyya distance. Classification experiments of hyperspectral data are carried out to prove the value of multifractal spectrum, and the classification accuracy reaches 95.2%. With 10% of the original spectra’s dimension, the accuracy reaches 82.2%. The fractal dimension of spectral subset with the same singularity exponent is characterized by multifractal spectrum, and the singularity distribution of spectra are is expressed sufficiently. As a conclusion, the method is appropriate to extract the features of hyperspectral data..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 844 (2009)
Thin Films
Impact of Buffer Layer on Cut-Off Properties of Reflection Spectra for Guided-Mode Resonance Filters
Wang Zhenhua, Wu Yonggang, Sang Tian, Wang Zhanshan, Peng Donggong, Jiao Hongfei, Chen Naibo, and Cao Hong
Guided-mode resonance (GMR) reflection filter is presented by adding a buffer layer which is used in design of homogeneous thin-film reflection filters. We use the rigorous coupled-wave theory for studying the improvement of buffer layer to cut-off properties of reflection spectra. For the double layers structures undeGuided-mode resonance (GMR) reflection filter is presented by adding a buffer layer which is used in design of homogeneous thin-film reflection filters. We use the rigorous coupled-wave theory for studying the improvement of buffer layer to cut-off properties of reflection spectra. For the double layers structures under a TE-polarized plane wave illumination, the width of reflection spectra is broadened obviously from 192.4 nm to 345.6 nm by adding a buffer layer 97.5 nm, and the reflected sideband depressed more than the structure without buffer layer in the wavelength range of 650～1250 nm. Analogously,the similar structure under a TM-polarized plane wave illumination at the Brewster angle can obtain wider cut-off spectral range and lower reflectance than the one without buffer layer in the range of 700～1300 nm. By optimizing the structures and choosing the compatible parameters of grating, we can get better cut-off properties of reflection spectra and hold the line on the resonant wavelength..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 3, 849 (2009)
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