Contents
2022
Volume: 42 Issue 20
28 Article(s)
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Diffraction and Gratings
Focusing Analysis of Single-Mode Photon Sieve with Equal-Diameter Pinholes Working in "Water Window" Band
Jirui Zhu, Qing Cao, Changjie Cheng, Chaoyue Li, Wenxuan Chen, and Yaxing Mao
As processing technologies become mature, and the requirement for spatial resolution increases, pinholes on the photon sieve get smaller and smaller. For pinholes with different sizes on the photon sieve, the incident uniform plane wave can excite one or more waveguide modes, which results in the inter-modal dispersionAs processing technologies become mature, and the requirement for spatial resolution increases, pinholes on the photon sieve get smaller and smaller. For pinholes with different sizes on the photon sieve, the incident uniform plane wave can excite one or more waveguide modes, which results in the inter-modal dispersion and phase difference. Even if there is only single-mode transmission in the pinholes, the effective refractive index of the fundamental mode is related to the size of the pinhole, which leads to different phases of pinholes with different diameters at the exit. To eliminate these phase differences, the single-mode photon sieve with equal-diameter pinholes is proposed. The focusing effect of the photon sieve in the "water window" band is studied, and the corresponding Gaussian far-field diffraction model is established. In addition, the distribution of the Gaussian mode field is confirmed based on the numerical simulation through the finite element software, and the effectiveness of the far-field model is verified by calculating the Fresnel diffraction integral..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2005001 (2022)
Fiber Optics and Optical Communications
Transoceanic Fiber Transmission System Based on Probabilistic Shaping and Dual-Subcarrier Multiplexing
Lingmin Xiong, Lianshan Yan, Lin Jiang, Anlin Yi, Wei Pan, and Bin Luo
Given the serious noise accumulation and the nonlinearity effect in transoceanic fiber communication systems, probabilistic shaping (PS) and subcarrier multiplexing (SCM) are combined to alleviate transoceanic transmission link impairments, so as to improve the transmission performance of these systems. The single-carrGiven the serious noise accumulation and the nonlinearity effect in transoceanic fiber communication systems, probabilistic shaping (PS) and subcarrier multiplexing (SCM) are combined to alleviate transoceanic transmission link impairments, so as to improve the transmission performance of these systems. The single-carrier and dual-subcarrier multiplexing systems are simulated by developing a simulation link of transoceanic fiber transmission with the commercial software VPI. The simulation results show that the transmission distances of the uniform (H=4) and PS (H=3.6, H=3.7, H=3.8) dual-subcarrier PDM-16QAM systems are respectively 2.3% (405 km), 21% (3698 km), 19.7% (3468 km), and 14.5% (2549 km) longer than that of the uniform (H=4) single-carrier PDM-16QAM system under the 20% forward error correction (FEC) threshold. Then, an experimental fiber loop transmission platform is built to verify the feasibility of the proposed scheme. According to the experimental results, the transmission distances of the uniform and PS (H=3.8) dual-subcarrier PDM-16QAM systems are respectively 5.6% (282 km) and 46.2% (2323 km) longer than that of the uniform single-carrier PDM-16QAM system under the 20% FEC threshold. In summary, both simulation and experimental results demonstrate that applying PS and SCM to transoceanic fiber communication systems can effectively enhance these systems' transmission performance..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2006001 (2022)
Sensor Based on D-Shaped Photonic Crystal Fiber for Detecting Chemicals with Low Refractive Index
Haiying Zhao, Lijuan Zhao, and Zhiniu Xu
In order to achieve high-sensitivity monitoring of drugs and chemical materials with low refractive index, a surface plasmon resonance (SPR) sensor with gold film plated in an open loop is designed based on the D-shaped photonic crystal fiber (PCF). The finite element method is adopted to systematically investigate theIn order to achieve high-sensitivity monitoring of drugs and chemical materials with low refractive index, a surface plasmon resonance (SPR) sensor with gold film plated in an open loop is designed based on the D-shaped photonic crystal fiber (PCF). The finite element method is adopted to systematically investigate the effects of open loop radius, the distance between the D-shaped structure and fiber core, and the thickness of gold film on the wavelength sensitivity of the proposed sensor. The results reveal that the maximum wavelength sensitivity of the PCF-SPR sensor reaches 15346 nm/RIU (RIU is refractive index unit) when the refractive index of analytes ranges from 1.28 to 1.32, and the corresponding resolution is 6.52×10-9 RIU. In view of the existing researches, the wavelength sensitivity and resolution of the proposed PCF-SPR sensor are 1.28-6.67 times and 153/1000-783/1000 of that of typical available PCF-SPR sensors within the same range of refractive index, respectively. Therefore, the proposed PCF-SPR sensor can be widely applied in fields such as biomedicine, food safety, and material monitoring..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2006002 (2022)
Optical Fiber Multi-Parameter Measurement Based on Machine Learning
Zehang Ma, Rui Gong, Bin Li, Li Pei, and Huai Wei
This paper proposes a method to extract the parameters to be measured from the incomplete information of the signal by machine learning. Instead of the data containing all the pulse amplitude and phase information, the method employs the power spectrum amplitude data containing only part of the signal information for pThis paper proposes a method to extract the parameters to be measured from the incomplete information of the signal by machine learning. Instead of the data containing all the pulse amplitude and phase information, the method employs the power spectrum amplitude data containing only part of the signal information for parameter extraction. It overcomes the difficulty in measuring the phase information of complex optical signals. Simulations verify the ability to utilize machine learning algorithms to extract the parameter information of transmission medium from pulse evolution and the feasibility of using the power spectrum of pulse without phase information to realize optical fiber multi-parameter measurement. The simulation results show that the mean square error of this method can be controlled below 0.3% with proper machine learning algorithms..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2006003 (2022)
Refractive Index Sensor Based on Excessively Tilted Fiber Grating Sagnac Vernier Interferometer
Hong Gu, Binbin Luo, Shenghui Shi, Xue Zou, Xiangwen Yang, Yujie Li, Huiji Chen, and Mingfu Zhao
An excessively tilted fiber grating (ExTFG) Sagnac interference loop refractive index sensor based on vernier effect (VE) is proposed. Utilizing the basic principle of the optical VE, a polarization-maintaining fiber Sagnac interferometer with a free spectral range (FSR) of 1.52 nm and a Sagnac interferometer composed An excessively tilted fiber grating (ExTFG) Sagnac interference loop refractive index sensor based on vernier effect (VE) is proposed. Utilizing the basic principle of the optical VE, a polarization-maintaining fiber Sagnac interferometer with a free spectral range (FSR) of 1.52 nm and a Sagnac interferometer composed of ExTFG with an FSR of 1.36 nm are theoretically designed and fabricated. The vernier spectrum is obtained by superimposing two optical paths by cascading. Experimental results show that the characteristics of the vernier envelope are easy to identify, and the refractive index sensitivity reaches -1286.40 nm/RIU through vernier amplification, improved ~8.46 and ~10.55 times than that of the TM and TE polarizations of the ExTFG sensors, respectively, which is in good agreement with the theoretically calculated result. The output spectrum of the sensor is relatively stable, and the sensor has the advantages of simple structure, convenient fabrication, and strong resistance of temperature crosstalk, leading to promising application in the fields of biochemical and biomedical detections..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2006004 (2022)
Mode Transmission Characteristics of Heterogeneous Helical Cladding Large Mode Area Fiber
Xiao Shen, Yingying Li, Tao Yang, Jiajin Zheng, Zuxing Zhang, and Wei Wei
A novel type of large mode area single mode fiber with heterogeneous helical cladding is proposed for 2.0 μm. Based on the coordinate transformation theory and the finite element simulation technology, a two-dimensional simulation model for a three-dimensional helical fiber is established, the mode transmission charactA novel type of large mode area single mode fiber with heterogeneous helical cladding is proposed for 2.0 μm. Based on the coordinate transformation theory and the finite element simulation technology, a two-dimensional simulation model for a three-dimensional helical fiber is established, the mode transmission characteristics of the fiber are analyzed, and the expected conclusions and optimized optical fiber parameters are obtained. The transmission loss of the fundamental mode is less than 0.1 dB/m, the transmission loss of high-order mode is more than 10.0 dB/m, the largest single-mode core diameter is up to 66 μm, and the mode field area is about 2360 μm2. When the fiber is bent, the helical slit width is reduced to about 9 μm. When the helix pitch Λ is increased to 26 mm and the minimum bending radius is 33 cm,the transmission loss of fundamental mode is 0.10 dB/m, and the transmission loss of high-order mode is greater than 10.08 dB/m. The proposed fiber has a long helix pitch and all-solid-state structure, parameters can be coordinated with each other, so it is conducive to preparation and use of optical fibers. The mode discrimination ability meets the requirements of large mode area single mode fiber. It is expected to be well applied in high power fiber lasers..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2006005 (2022)
Fourier Optics and Signal Processing
Low Phase Noise Microwave Signal Generation Based on Soliton Frequency Comb in MgF2 Microresonator
Jian Dai, Xinmin Li, Anni Liu, Yinggang Hou, and Kun Xu
Integration and low phase noise are the inevitable trend and practical basis for the development of microwave signal sources. The highly coherent soliton frequency combs in microresonators provide an effective technical approach for the generation of new integrated low-phase noise microwave signals. In this paper, the Integration and low phase noise are the inevitable trend and practical basis for the development of microwave signal sources. The highly coherent soliton frequency combs in microresonators provide an effective technical approach for the generation of new integrated low-phase noise microwave signals. In this paper, the stable generation and coherent beat frequency of soliton mode-locked frequency comb are realized based on a high-quality magnesium fluoride crystal microdisk cavity. Finally, 15.38 GHz microwave signal with the phase noise of -120 dBc/Hz@10 kHz is obtained, which shows the application advantages of miniaturization and low phase noise. It will provide an important technical support for the development of integrated high-performance microwave signal sources in the future..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2007001 (2022)
Imaging Systems
Simulation Analysis of Target Restoration in Digital Holographic Scattering Imaging
Meifang Xu, Meijie Zhang, Erming Tian, Haoquan Wang, and MinJuan Zhang
Target restoration in transmission scattering imaging has attracted much attention in the fields of biomedicine, remote sensing, and security. In this paper, we construct a target restoration model based on the digital holographic scattering imaging theory. The key factors affecting the target restoration in the model Target restoration in transmission scattering imaging has attracted much attention in the fields of biomedicine, remote sensing, and security. In this paper, we construct a target restoration model based on the digital holographic scattering imaging theory. The key factors affecting the target restoration in the model are systematically simulated and analyzed, such as the center wavelength of the laser source, target size, observation distance, scattering medium characteristics, and detector resolution. The results show that the laser source with a central wavelength of 635.5 nm, a detector with an observation distance of 50 cm and a spatial resolution of 512 pixel×512 pixel, a diffuser with a root mean square roughness of 333 μm, and the diffuser with Gaussian random distribution model under close root mean square roughness conditions, are more conducive to the target restoration. This research provides a basis for the rapid and accurate construction of an image restoration system applied in transmission scattering imaging..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2011001 (2022)
Ultrafast Imaging Based on Polarization Encoding
Qifan Zhu, Yi Cai, Xuanke Zeng, Hu Long, Liangwei Zeng, Yongle Zhu, Jingzhen Li, and Xiaowei Lu
Among the current single-shot ultrafast imaging methods, the direct imaging methods have high resolutions but complex detection systems, while the computational ones have simple detection systems but easily impaired spatial resolutions. Therefore, ultrafast imaging based on polarization encoding is proposed. This imagiAmong the current single-shot ultrafast imaging methods, the direct imaging methods have high resolutions but complex detection systems, while the computational ones have simple detection systems but easily impaired spatial resolutions. Therefore, ultrafast imaging based on polarization encoding is proposed. This imaging system uses a half-wave plate array and a polarizer array to achieve polarization encoding of the incident femtosecond pulses, emergent femtosecond pulses and dynamic events, and it decodes the ultrafast dynamic time-series images by linear simultaneous equations. Then, several images are accurately restored by constructing an optical model and conducting simulations, and the feasibility of the proposed scheme is verified. In theory, its framing rate can reach more than 1013 frame/s, and its intrinsic spatial resolution can be as high as 114 lp/mm. The proposed imaging system combines the advantages of direct and computational imaging systems. Specifically, the results of linear simultaneous equations are accurate, which frees the optical system from resolution impairments. Besides, the superposition of time-series images allows the detection structure to split beams alone, thereby saving the effort of dividing the images of different moments spatially and ultimately simplifying the detection structure. The temporal resolution of the proposed ultrafast imaging system is only constrained by pulse width. This system can be used to achieve the detection of femtosecond dynamic events, and its temporal resolution can be further enhanced by narrowing pulse width..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2011002 (2022)
Instrumentation, Measurement and Metrology
Global Curve Fitting for Structured Illumination Microscopy with High Thickness Detection Resolution
Kejun Yang, Chenhaolei Han, Lei Liu, Jinhua Feng, Zhongye Xie, Song Hu, and Yan Tang
This paper proposes structured illumination microscopy that utilizes the global information in the curve of modulation depth response to identify overlapping peaks and obtains the height of each surface of the thin film sample analytically with an optimization algorithm under boundary constraints. Measurement of layer This paper proposes structured illumination microscopy that utilizes the global information in the curve of modulation depth response to identify overlapping peaks and obtains the height of each surface of the thin film sample analytically with an optimization algorithm under boundary constraints. Measurement of layer thickness distribution and surface morphology reconstruction are thereby achieved in a manner of high thickness resolution, high accuracy, and rapid calculation. According to the simulation analysis, the proposed method improves the thickness detection resolution from 483 nm to 175 nm under ideal conditions. Furthermore, experiments show that the proposed method reduces the number of iterations and offers high repeatability accuracy..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2012001 (2022)
High-Precision Camera Calibration Method Based on Sub-Pixel Edge Detection
Qun Lou, Lü Junhao, Lihua Wen, Jinyou Xiao, Guangxi Zhang, and Xiao Hou
In many practical application scenarios, the camera calibration is not highly accurate due to unclear calibration images and low target detection accuracy, which limits the improvement of measurement accuracy. To solve this problem, a binocular camera calibration method based on sub-pixel edge detection is proposed. ThIn many practical application scenarios, the camera calibration is not highly accurate due to unclear calibration images and low target detection accuracy, which limits the improvement of measurement accuracy. To solve this problem, a binocular camera calibration method based on sub-pixel edge detection is proposed. The initial integer-pixel edge values of the target identification points are obtained by an adaptive double-threshold Canny operator. In addition, the initial integer-pixel edge values are taken as the center to estimate the second-order edge parameters of a discontinuous edge model based on the partial area effects, and ellipse fitting on the set of sub-pixel edge points is performed to obtain the accurate position of the target identification points. Finally, the set of the identification points used to solve the calibration parameters is obtained by correcting the sorting position of these points, which thus achieves the high precision calibration of cameras under complex environments. The test experiments on typical calibration scenarios show that, compared with the existing methods, the proposed method can improve the calibration accuracy by 23% in a conventional environment and 68% in a high-temperature oven environment with low contrast and relative resolution, respectively..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2012002 (2022)
Topological Optimization Design of Imaging Primary Mirror Based on Root-Mean-Square Error of Surface Figures
Ke Chen, and Rongsheng Qiu
The topological optimization design of a primary mirror is carried out to resolve the contradiction between the excessive change in the surface figures and the light weight of the primary mirror under high rotation speed. The primary mirror is divided into hexahedral elements by HyperMesh software, and the displacementThe topological optimization design of a primary mirror is carried out to resolve the contradiction between the excessive change in the surface figures and the light weight of the primary mirror under high rotation speed. The primary mirror is divided into hexahedral elements by HyperMesh software, and the displacement of all nodes on the two surfaces of the primary mirror along the central axis of the primary mirror is defined as the response. The root-mean-square (RMS) error of surface figures (relative to static surface figures) is used to evaluate the surface figure change of the primary error and is taken as the optimization constraint, and then the topological optimization of the primary mirror is performed with the goal of the lightest weight. The optimized structure is reconstructed geometrically and substituted into OptiStruct for recalculation; the primary mirror is processed according to the reconstructed model, and the RMS error of surface figures after optical fabrication is measured by an interferometer. The optimization results indicate that the RMS error of the surface figures is below 0.35 μm, and the weight is reduced by 38.54%. The surface figure accuracy of single-point turning is 0.08 μm (obtained by calibration), and thus the RMS error of surface figures after optical fabrication does not exceed (0.35+0.08) μm in theory. The surface figures of mirror 1 and mirror 2 measured by the interferometer after light addition have an error of 0.36 μm and 0.31 μm separately relative to the theoretical surface figures of the single-point turning, which are all less than 0.5 μm..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2012003 (2022)
Moire Fringes Simulation in Liquid Crystal Display
Chengxiang Guo, Qinquan Zhang, Jiarui Ji, Lei Yang, and Hongbo Xie
In the liquid crystal television display module, the multilayer backlight diaphragm and pixel panel both have periodic structures, and their use in combinations often results in obvious moire fringes, which seriously affects the actual visual effect. Therefore, it is important to establish a theoretical model of moire In the liquid crystal television display module, the multilayer backlight diaphragm and pixel panel both have periodic structures, and their use in combinations often results in obvious moire fringes, which seriously affects the actual visual effect. Therefore, it is important to establish a theoretical model of moire fringes in the liquid crystal display (LCD) module and carry out simulation analysis to explore methods for decreasing or eliminating moire fringes. Here, a moire fringe model with bilayer prismatic diaphragm based on Zemax is established, and it is combined with an eye observation model to simulate the visual effect of human eyes on the moire fringes in the LCD screen. In addition, the theoretical models of the backlight diaphragm and pixel panel are constructed in MATLAB. By changing parameters including the cycle size and rotation angle of the backlight diaphragm and the pixel panel, the parameters including the size and angle of the moire fringe are simulated and analyzed, and the effect of moire fringes determined by the human eye observation on the display is considered comprehensively..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2012004 (2022)
Integrated Optics
Delay Measurement Stability of Silicon-Based Optical Switching Delay Line Chip
Shangqing Shi, Pengcheng Liu, and Binfeng Yun
Silicon-based optical switching delay line chip has a good application prospect in microwave photonic beamforming due to its simple structure and large instantaneous bandwidth. However, there are many difficulties in it's high-precision delay measurement, and the factors affecting the delay measurement stability arSilicon-based optical switching delay line chip has a good application prospect in microwave photonic beamforming due to its simple structure and large instantaneous bandwidth. However, there are many difficulties in it's high-precision delay measurement, and the factors affecting the delay measurement stability are needed to be studied. By comparing the delay measurement stabilities of a delay test link based on optical vector network analyzing system, alignment waveguide and delay line, the main factors affecting the delay measurement stability of silicon-based optical switching delay line are analyzed experimentally. Experimental results show that chip insertion loss, input/output grating coupler package and residual Mach-Zehnder interference of delay line chip will deteriorate the on-chip delay measurement stability..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2013001 (2022)
Lasers and Laser Optics
Process Optimization for MOPA Fiber Laser Engraving of Carbon Steel
Dungang Zhang, Wenshu Luo, Jing Dong, Hailin Wang, Xiao Zhu, and Guangzhi Zhu
High-power nanosecond fiber lasers have been widely used in laser engraving. In this paper, the effects of pulse width, energy density, and pulse repetition frequency (PRF) on laser engraving results are studied by using a master oscillator power amplifier (MOPA) fiber laser system, with carbon steel as the research maHigh-power nanosecond fiber lasers have been widely used in laser engraving. In this paper, the effects of pulse width, energy density, and pulse repetition frequency (PRF) on laser engraving results are studied by using a master oscillator power amplifier (MOPA) fiber laser system, with carbon steel as the research material. The material removal rate (MRR) and average surface roughness (Sa) of each group of parameters are measured by a three-dimensional (3D) profilometer. It is found that longer pulse width and higher energy density can result in larger MRR and Sa. Larger MRR and Sa can also be obtained with short pulse width and high energy density, which is caused by a high pulse overlap rate. There is a critical PRF that can simultaneously make MRR large and Sa small. Finally, the optimized process parameters are used to achieve the engraving effects of high quality and high MRR..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2014001 (2022)
Materials
Analysis of Inverted GaInP/GaAs/InGaAs Triple-Junction Solar Cell Failure
Yi Zhang, Junhua Long, Qiangjian Sun, Jingjing Xuan, Xuefei Li, Xia Wang, Zhitao Chen, Xiaoxu Wu, and Shulong Lu
Inverted GaInP/GaAs/InGaAs triple-junction solar cells are fabricated by substrate lift-off and temporary bonding techniques, and their reliability is investigated. The reliability test in an environment with a temperature of 85 ℃ and a relative humidity of 85% finds that the initial photoelectric conversion efficiencyInverted GaInP/GaAs/InGaAs triple-junction solar cells are fabricated by substrate lift-off and temporary bonding techniques, and their reliability is investigated. The reliability test in an environment with a temperature of 85 ℃ and a relative humidity of 85% finds that the initial photoelectric conversion efficiency of the triple-junction cells drops sharply from 31.86% to 24.84% when the damp heat test is performed for 144 h. As the test time increases, the solar cell performance is relatively stable. External quantum efficiency and electroluminescence spectroscopy tests show that the degradation of the triple-junction cell performance mainly comes from the GaInP top cell. Under the high temperature and high humidity environment, the distribution of the element concent in the AlInP window layer changes, which results in the enhanced spectral reflectance of the material in the range from 340 nm to 480 nm. In addition, the aggregation of the high-concent Al element leads to an increase in the defect density of the top cell and a decrease in the carrier's collection efficiency of the GaInP top cell, which thus limits the overall performance of triple-junction solar cells. The results of secondary ion mass spectrometry (SIMS) also visually demonstrate this phenomenon. The results of this study prove that the AlInP window layer has an important impact on the environmental stability of multi-junction solar cells..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2016001 (2022)
Medical Optics and Biotechnology
Optical Fiber Photoacoustic Blood Oxygen Saturation Measurement and Functional Imaging
Wubing Fu, Yizhi Liang, Xiaoxuan Zhong, Jie Huang, Long Jin, and Baiou Guan
Based on the differences of arteriovenous blood in the optical absorption spectrum, photoacoustic functional imaging obtains the spatial distribution of blood oxygen saturation in biological tissues by multi-wavelength photoacoustic excitation and detection, which provides important functional information for medical rBased on the differences of arteriovenous blood in the optical absorption spectrum, photoacoustic functional imaging obtains the spatial distribution of blood oxygen saturation in biological tissues by multi-wavelength photoacoustic excitation and detection, which provides important functional information for medical research and disease diagnosis. However, limited by the ultrasonic detection sensitivity of piezoelectric sensors, miniaturized photoacoustic imaging technology has a large error in the measurement of blood oxygen saturation, and the functional imaging capability is difficult to meet medical requirements. To address this problem, a distributed feedback Bragg fiber laser is considered as a sensitive element to detect weak photoacoustic signals, and the perturbation caused by ultrasound is read by the beat frequency between two orthogonal laser modes. The frequency noise of the laser is effectively suppressed by optical amplification, and thus the high-spatial-resolution functional imaging results of in vivo brain tissues and blood vessels in the rectum lining are obtained..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2017001 (2022)
Optical Design and Fabrication
Validation on Two Optical-Mechanical Integration Modeling Methods for Solar Concentrator Under Load
Jian Yan, Youduo Peng, Yongxiang Liu, and Yaosong Hu
In this paper, we have carried out a validation study on two optical-mechanical integration modeling methods, including the mirror pose reconstruction method that only considers the spatial pose change of mirror surface units under load (ignoring the elastic deformation of the mirror surface) and the plane element subsIn this paper, we have carried out a validation study on two optical-mechanical integration modeling methods, including the mirror pose reconstruction method that only considers the spatial pose change of mirror surface units under load (ignoring the elastic deformation of the mirror surface) and the plane element substitution method proposed in this paper. The proposed method works by converting the reflecting mirror surface of the solar concentrator into many discrete plane elements and directly establishing the geometric optical information from deformation information of plane elements, so as to realize the data unification and integration of the optical-mechanical analysis, and the integration model of optical-mechanical information of the reflecting mirror is established. The results of focused flux distributions from the two optical-mechanical integration methods are verified jointly and compared with the measuring results from the experiment of solar concentrator under load, which fully demonstrates the effectiveness of the two methods. When the elastic deformation of all reflecting mirror surfaces in the concentrator is large, the mirror pose reconstruction method cannot accurately predict the optical performance of concentrators. However, the plane element substitution method can fully consider any deformation (elastic deformation and rigid body displacement) of the reflecting mirror under load and accurately predict the focused performance with its universality and simplicity. Experiments show that for low focused flux density, it is feasible to use rough white paper (printing paper) as the Lambertian surface to measure the focused flux density..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2022001 (2022)
Optical Devices
Novel Se Microtube/Spiro-MeOTAD Heterojunction Photodetector
Shiliang Feng, Rongpeng Chen, Weiwei Wang, Pingping Yu, and Yanfeng Jiang
Organic semiconductor materials have been widely used in photodetectors due to their eco-friendly property and excellent photoelectric property. In this paper, a novel Se/Spiro-MeOTAD heterojunction is fabricated by the spin-coating method combining p-type organic semiconductor materials Spiro-MeOTAD and Se microtube (Organic semiconductor materials have been widely used in photodetectors due to their eco-friendly property and excellent photoelectric property. In this paper, a novel Se/Spiro-MeOTAD heterojunction is fabricated by the spin-coating method combining p-type organic semiconductor materials Spiro-MeOTAD and Se microtube (Se-MT). The Se/Spiro-MeOTAD photodetector has excellent responsivity and switching ratio in the wavelength range from 350 nm to 800 nm and consumes no extra bias voltage, which shows favorable self-powered photoelectric properties. Compared with a single Se-MT device (0.1 V), the Se/Spiro-MeOTAD photodetector improves the responsivity by 10 times to 36.5 mA·W-1 when the wavelength is 410 nm and the bias voltage is 0 V. The switching ratio is 156 (an enhancement of 800%), and the rise time and decay time reduce to 22 ms and 35 ms, respectively. The results show that organic semiconductor materials can effectively improve the photoelectric properties of inorganic semiconductors, and inorganic/organic heterojunction can be used to fabricate high-performance photoelectric devices..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2023002 (2022)
Dither-Free Quad- and Null-Bias Point Locking Technique for Mach-Zehnder Silicon Optical Modulator
Jiekui Yu, Honggang Chen, Bo Zhang, Yuan Cheng, Yong Luo, Xuerui Liang, and Leilei Hu
A dither-free Quad- and Null-bias point locking scheme for Mach-Zehnder (MZ) silicon optical modulators is presented. In this scheme, a pair of differential monitoring photodetectors (MPDs) (an inphase-MPD in the same phase as the output and an outerphase-MPD with a 180° phase difference to the output) are used asA dither-free Quad- and Null-bias point locking scheme for Mach-Zehnder (MZ) silicon optical modulators is presented. In this scheme, a pair of differential monitoring photodetectors (MPDs) (an inphase-MPD in the same phase as the output and an outerphase-MPD with a 180° phase difference to the output) are used as the signal feedback components for closing-loop control. The ratio of the inphase-MPD current to the outerphase-MPD current is denoted as the normalized photocurrent, which is then used to construct the error functions for the Quad point (90° phase bias) and the Null point (180° phase bias). For Quad point locking, the error function is the difference between the normalized photocurrent and the responsivity ratio of the inphase-MPD and outerphase-MPD. For Null point locking, the error function is the first derivative of the normalized photocurrent relative to the thermal power bias point of the thermo-optic phase shifter, and the adjustment direction of the bias power is determined by the positive or negative sign of the second derivative. Then, the theoretical expression of the algorithm is derived according to the theoretical model of the MZ silicon optical modulator, and the proposed algorithm is verified by simulation. The verification results are in agreement with the conclusions of the mathematical derivation formula. Finally, a 53 GBaud 4-level pulse amplitude modulation (PAM4) test platform and a 53 GBaud binary phase-shift keying (BPSK) simulation platform are built to validate the accuracy of the proposed algorithm in Quad and Null point locking for MZ silicon optical modulators..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2023003 (2022)
Optics at Surfaces
Design of Terahertz Low-Loss Transmission Line and Band-Stop Filter Based on Spoof Surface Plasmon Polaritons
Huali Zhu, Yong Zhang, Longfang Ye, Yukun Li, Zhang Dang, Yang Chen, Ruimin Xu, and Bo Yan
In this paper, a terahertz low-loss transmission line based on spoof surface plasmon polaritons (SSPPs) is proposed, and a terahertz rejection filter with high isolation is demonstrated by loading split-ring resonators (SRRs). The SSPPs-based transmission line is optimized by an irregular gradient transition structure,In this paper, a terahertz low-loss transmission line based on spoof surface plasmon polaritons (SSPPs) is proposed, and a terahertz rejection filter with high isolation is demonstrated by loading split-ring resonators (SRRs). The SSPPs-based transmission line is optimized by an irregular gradient transition structure, and thus its transmission loss and unevenness in the terahertz frequency band are reduced. Then, the frequency band suppression mechanisms of the SSPPs-based transmission line loaded with SRRs and without SSRs are revealed through the dispersion analysis. When the SSPPs-based transmission line loaded with SRRs operates under the fundamental mode and the first-order high mode separately, its fundamental mode is characterized by low pass while its first-order high mode features bandpass, and thus the terahertz filtering characteristic of pass-stop-pass-stop is achieved. In addition, by adjusting the geometric parameters of SRRs, we can control the stop-band frequency of the SSPPs-based filter and improve the suppression depth of the SSPPs filter by increasing the number of loaded SRRs. To demonstrate the feasibility of the design, this study conducts terahertz on-wafer tests for the proposed SSPPs-based transmission line and filter prepared by micro-nano fabrication. The results reveal that in the frequency band of 0.11-0.17 THz, the insertion loss of the SSPPs-based transmission line is less than 0.5 dB/mm, and the return loss is better than 10 dB; in the frequency band of 0.142-0.156 THz, the suppression depth of the SSPPs-based filter is greater than 10 dB, and the maximum suppression depth is up to 45 dB at 0.148 THz. The experimental results are in good agreement with the simulated ones. The research is of great significance to the integrated system of terahertz plasmons..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2024001 (2022)
Preparation and Optical Properties of Polarization-Dependent Nano-Gap Array
An Ping, Haibin Ni, Jianxin Cheng, and Jianhua Chang
A metal nano-gap array with polarization-dependent optical properties prepared by self-assembly technology of microspheres is proposed. The structure is fabricated based on the mask of periodic polystyrene (PS) microsphere film, followed with tilted vacuum evaporation coating of metal film. The relationship between theA metal nano-gap array with polarization-dependent optical properties prepared by self-assembly technology of microspheres is proposed. The structure is fabricated based on the mask of periodic polystyrene (PS) microsphere film, followed with tilted vacuum evaporation coating of metal film. The relationship between the transmission spectrum of the nano-gap array and the incident polarization angle is measured, and it exhibits polarization-dependent properties that can be used as optical switches. The finite-difference-time-domain (FDTD) method is used to simulate the transmission spectrum of the nano-gap array and the electric field intensity distributions at the resonant wavelengths. Furthermore, the surface plasmon modes and the influence of geometry parameters on transmission spectra are studied. The refractive index sensitivity of this structure reaches as high as 992 nm/RIU..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2024002 (2022)
Physical Optics
Tight Focusing Properties of Gaussian Beams with Asymmetric Off-Axis Bi-Phase Singularities
Xiyu Yan, Yanfang Yang, Ying He, Lulu Li, and Junjie Wang
The center of a vortex beam is a phase singularity, and in general, the vortex axis (i.e., the phase singularity) of the vortex beam is on the optical axis of the beam. Due to consideration errors, however, a generated vortex beam is off-axis to some extent, and therefore, it is of great application value to investigatThe center of a vortex beam is a phase singularity, and in general, the vortex axis (i.e., the phase singularity) of the vortex beam is on the optical axis of the beam. Due to consideration errors, however, a generated vortex beam is off-axis to some extent, and therefore, it is of great application value to investigate the characteristics of beams with off-axis phase singularities. In this paper, the tight focusing properties of radially polarized Gaussian beams with asymmetric off-axis bi-phase singularities upon passing through a lens with a large numerical aperture are investigated on the basis of the Richards-Wolf vector diffraction theory. In particular, the influences of off-axis distance and the vortex topological charge number on the focusing field are analyzed. The results reveal that the relative quantities of two off-axis distances and the corresponding two topological charge numbers have a consistent influence on the offset direction of the maximum light intensity of the focusing field. In addition, it is found that dark core splitting occurs in the focusing field of high-order vortex beams. Thus, multiple dark cores appear, and the number of dark cores is equal to the sum of two vortex topological charge numbers subtracted by 1..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2026001 (2022)
Circular Airy Amplitude Modulation and Its Optimization for Propagation Characteristics in Turbulence
Zeyu Zhou, Xiuhua Yuan, and Feng Zhou
In this paper, partially coherent beams (PCBs) are modulated by circular Airy amplitude to solve the problem of beam expansion of PCBs. The effects of Airy function scaling factor, truncation radius, and coherence length on the self-focusing distance and focusing intensity of the beam, as well as the optical intensity In this paper, partially coherent beams (PCBs) are modulated by circular Airy amplitude to solve the problem of beam expansion of PCBs. The effects of Airy function scaling factor, truncation radius, and coherence length on the self-focusing distance and focusing intensity of the beam, as well as the optical intensity scintillation index of partially coherent circular Airy beam in turbulent environment, are studied. The results show that by modulating the circular Airy amplitude, the focusing distance of PCBs can be controlled, and the beam divergence can be reduced while retaining PCB to combat turbulence and reducing intensity flicker. The light intensity flicker at the focal point is further reduced compared with the original PCB..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2026002 (2022)
Design of Non-Paraxial Accelerating Array Beams Based on Wigner Function
Yi Li, Xingchun Chu, Zhongxiang Han, and Hanling Tang
A tunable non-paraxial accelerating beam generation method is proposed, which can make the beam propagate along arbitrary convex trajectories without paraxial approximation. The explicit expression between amplitude phase in Fourier space and accelerating propagation trajectory is derived by using the Wigner function aA tunable non-paraxial accelerating beam generation method is proposed, which can make the beam propagate along arbitrary convex trajectories without paraxial approximation. The explicit expression between amplitude phase in Fourier space and accelerating propagation trajectory is derived by using the Wigner function and the caustics principle. Moreover, a non-paraxial accelerating array beam with self-focusing properties is generated by designing the initial angular spectra of the Fourier space. The influences of beam number, array radius, and beam parameter size on focus position and autofocus performance are analyzed. The results show that the self-focusing array beam generated by this method breaks through the limit of paraxial approximation, and the beam trajectory and control method are more flexible and efficient..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2026003 (2022)
Coherence Switch in Spatiotemporal Coherent Vortices
Chaoliang Ding, Xiexing Qi, and Liuzhan Pan
The coherence theory of the non-stationary light field is combined with the generalized Huygens-Fresnel diffraction integral to investigate the evolution of spatiotemporal coherent vortices (STCVs) during the propagation in a dispersive medium. The expression of the mutual coherent function of partially coherent pulsedThe coherence theory of the non-stationary light field is combined with the generalized Huygens-Fresnel diffraction integral to investigate the evolution of spatiotemporal coherent vortices (STCVs) during the propagation in a dispersive medium. The expression of the mutual coherent function of partially coherent pulsed beams with STCVs at the propagation distance z is derived, and the mathematical and physical description of the STCVs is obtained. The results show that a coherence switch of STCVs occurs during the propagation in the fused silica medium. The spatial coherence width and temporal coherence length of the pulsed light source can be regarded as the control parameters of the coherence switch to control the transmission of STCV information. The size of the coherence switch area depends heavily on the propagation distance. The size of the coherence switch area is large when the propagation distance is short, otherwise, it is small. Moreover, an optical communication model based on a coherence switch is designed..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2026004 (2022)
Spectroscopy
Calibration-Free Wavelength Modulation Spectroscopy Method Based on the Height-Width Characteristic of Second Harmonic
Yihong Wang, Bin Zhou, Rong Zhao, and Bubin Wang
This paper proposes a calibration-free wavelength modulation spectroscopy (WMS) method based on the height-width characteristic of the second harmonic and gives the analytical expression of the height and width of the second harmonic for the spectral adsorption factor considering the Voigt line-shape function under arbThis paper proposes a calibration-free wavelength modulation spectroscopy (WMS) method based on the height-width characteristic of the second harmonic and gives the analytical expression of the height and width of the second harmonic for the spectral adsorption factor considering the Voigt line-shape function under arbitrary modulation index. Compared with the traditional harmonic waveform fitting method, this method only requires filtering processing once and has lower requirements for computing resources. Instead of using spectral parameters such as collisional broadening coefficients and temperature-dependent indexes from the HITRAN 2020 database, it is theoretically more suitable for measurements under complex gas components. A WMS measurement system is set up in the laboratory to measure the mole fraction of CH4 at room temperature. The experimental results reveal that when the mole fraction of CH4 is greater than 2.08×10-3 under the 20 cm optical path, the relative deviation of the proposed method is less than 2%..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2030001 (2022)
Detection Method of Bubble Characteristic Parameters Based on Optical Fiber Spectroscopy
Zhicheng Liu, Xichen Wang, Chao He, Jiannan Yao, Ke Yang, Feng Ge, and Nianbing Zhong
To quantitatively detect the bubble size (cross-sectional diameters of bubbles), bubble frequency, and bubble rising velocity in gas-liquid two-phase flow, this study proposes a method for quantitative detection of the bubble characteristic parameters based on optical fiber spectroscopy. First, an optical system for thTo quantitatively detect the bubble size (cross-sectional diameters of bubbles), bubble frequency, and bubble rising velocity in gas-liquid two-phase flow, this study proposes a method for quantitative detection of the bubble characteristic parameters based on optical fiber spectroscopy. First, an optical system for the detection of bubble characteristic parameters is constructed with the near-infrared optical fiber spectrometer, plano-convex lens, multi-mode silica optical fiber, high-speed camera, gas-liquid two-phase flow pipeline, and syringe pump. Second, the theoretical models for quantitative detection of bubble size, frequency, and velocity in gas-liquid two-phase flow are built. Third, Zemax is used to simulate and analyze the optical transmission path in the optical measurement system. Finally, the performance of the optical measurement system in quantitative detection of bubble characteristic parameters is experimentally studied. The results indicate that the bubble size, frequency, and velocity in gas-liquid two-phase flow can be detected quantitatively by the proposed method, and the maximum relative detection errors of them are 9.8%, 8.1%, and 8.7%, respectively..
Acta Optica Sinica
- Publication Date: Oct. 25, 2022
- Vol. 42, Issue 20, 2030002 (2022)
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