2024

• Record 385 of
  
  Title:Ultrahigh sensitivity terahertz refractive index sensor based on four-inscribed hole defect photonic crystal structure
  
  Author(s):Wen, Jin(1,2); Sun, Wei(1); Liang, Bozhi(1); He, Chenyao(1); Xiong, Keyu(1); Wu, Zhengwei(1); Zhang, Hui(1); Yu, Huimin(1); Wang, Qian(1)
  Source: Microwave and Optical Technology Letters  Volume: 66  Issue: 1  DOI: 10.1002/mop.33892  Published: January 2024  
  Abstract:We proposed and investigated an ultrahigh sensitivity terahertz (THz) refractive index sensor based on four-inscribed hole defect photonic crystal structure. Due to the formation of resonant modes, the sensing properties can be obtained by shifting the sharp resonance in the transmission spectrum as changing of the analyte refractive index. In addition, the influence of structure parameters on the sensing performance is explored and demonstrated numerically. The numerical results illustrate that the Q-factor and figure of merit reach 323.71 and 167.188 can be obtained under the optimized structural parameters. In particular, an ultrahigh sensitivity of 198.8 μm/RIU can be realized in the frequency range of 0.777–0.779 THz. The proposed sensor may find significant applications in biochemical sensing systems. © 2023 Wiley Periodicals LLC.
  Accession Number: 20233814748894
• Record 386 of
  
  Title:The temperature variation of different cooling methods for the preparation of chalcogenide glasses
  
  Author(s):Fan, Wenwen(1); Xu, Junfeng(1); Yao, Zhirui(1); Li, Na(1); Li, Xuyang(2)
  Source: Infrared Physics and Technology  Volume: 136  Issue:   DOI: 10.1016/j.infrared.2023.105083  Published: January 2024  
  Abstract:The cooling rate has a great influence on the performance of chalcogenide glass, but it is unclear how much the actual cooling rate changes with different cooling methods. In this study, the infrared thermal imaging technology was employed to observe the temperature change in various cooling methods. The temperature curves and the cooling rates between different cooling methods were analyzed from the infrared images. The results show that at 250 °C, the cooling rates follow the order: water quenching > air compressor cooling > salt bath cooling > air cooling > asbestos wrapping cooling; whereas at 150 °C, the sequence is: water quenching > air compressor cooling > air cooling > asbestos wrapping cooling > salt bath cooling. Then the temperature changes inside the sample was simulated and the result shows that the temperature gradient of water quenching is much greater than that of air cooling method, which is why cracks often appear in the glass prepared by water quenching. Finally, Gex-S(90-x)-Sb10 glass was successfully prepared using the air cooling method and it shows excellent optical properties that can transmit both visible and infrared light. © 2023 Elsevier B.V.
  Accession Number: 20240115321626
• Record 387 of
  
  Title:Underwater Blue-green Light Weak Signal Detection Based on Adaptive Stochastic Resonance
  
  Author(s):Zhang, Jianlei(1); Zhang, Juan(1); Zhu, Yunzhou(2); Yao, Xinyu(1); Wu, Qianqian(1); Yang, Yi(1); He, Fengtao(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 53  Issue: 3  DOI: 10.3788/gzxb20245303.0301003  Published: March 2024  
  Abstract:The optical signal is easy to be absorbed and scattered during transmission with Underwater Optical Wireless Communication（UWOC）technology，resulting in serious optical power attenuation and further affecting the signal quality. In order to realize long-distance data transmission，it is very important to recognize，enhance and extract weak light signal under low Signal-to-Noise Ratio（SNR）. Stochastic resonance produces synergistic effect through nonlinear system，weak driving signal and appropriate amount of noise under certain conditions，which not only improves the output signal-to-noise ratio，but also detects useful signals. However，the current parameter selection of stochastic resonance system depends on artificial setting，which is not flexible enough to give full play to the advantages of stochastic resonance signal detection. In this paper，an adaptive stochastic resonance detection scheme based on multi-strategy fusion particle swarm optimization is proposed by analyzing the characteristics of weak underwater light signals and the conditions of stochastic resonance generation. It solves the problem that traditional particle swarm optimization is easy to fall into local optimization resulting in low convergence accuracy and difficult convergence. By introducing adaptive inertia weights to dynamically adjust the local search ability and global search ability of particles，the convergence speed of the algorithm is accelerated. In the process of particle evolution，neighborhood detection is used to strengthen the detection of local extremum location neighborhood，which makes the search radius of the algorithm larger in the initial stage of evolution，and gradually decreases with the increase of iteration times，which increases the refinement ability of the algorithm. Using Cauchy variation and reverse learning interactive strategy to mutate the optimal solution，the local optimal solution in Particle Swarm Optimization is broken，and the ability of the algorithm to escape from local space is effectively improved. In order to evaluate the feasibility and effectiveness of the proposed algorithm，simulation is carried out under the established UWOC weak signal detection system. Considering the special property of pilot signal，that is，some known data is inserted at the sending end and can be accurately extracted at the receiving end，it can be used as a reliable reference signal for parameter estimation. Therefore，this paper selects a specific number of code elements for parameter optimization. By taking the output SNR of the system as the selection index，the optimal system parameter which makes the output SNR maximum is searched and iterated continuously within the preset algorithm parameter range. The optimal system parameters are substituted into the fourth-order Runge-Kutta equation，the output response is obtained by discretization，and the weak light signal is detected. Finally，the error performance of bipolar non-return-to-zero signal with white Gaussian noise is compared under four detection schemes：non-stochastic resonance，fixed parameter stochastic resonance，adaptive stochastic resonance based on particle swarm optimization algorithm and multi-strategy fusion particle swarm optimization algorithm. The simulation results show that the bit error rate performance of the non-stochastic resonance system is worse than that of the other three detection schemes，and the bit error rate performance of the fixed parameter stochastic resonance system has limitations. Adaptive stochastic resonance can significantly improve the bit error rate performance of the system，especially above -6 dB，and the improvement effect is very obvious. Compared with the adaptive stochastic resonance based on particle swarm optimization algorithm，the proposed algorithm has faster convergence speed， more accurate optimization results and less error performance. In order to verify the effectiveness and feasibility of the proposed method， a UWOC experimental system is established. The experimental results show that when the received signal-to-noise ratio is - 1.7 dB，the bit error rate of the proposed algorithm can reach 2×10-4，and its performance is better than that of NO-SR and F-SR， which once again verifies the effectiveness of the proposed algorithm. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20241215774978
• Record 388 of
  
  Title:Direct femtosecond laser writing fiber Bragg gratings in double-D cladding chalcogenide glass infrared fibers
  
  Author(s):Liu, Lutao(1,2); Li, Xingyong(3); Xu, Yantao(1,2); Chen, Fengyi(3); Xiao, Xusheng(1,2); He, Wentao(1,2); Wang, Ruohui(3); Zhang, Peiqing(4); Yu, Yongsen(5); Guo, Haitao(1,2)
  Source: Optics and Laser Technology  Volume: 174  Issue:   DOI: 10.1016/j.optlastec.2024.110586  Published: July 2024  
  Abstract:Chalcogenide glass (ChG) fiber Bragg grating (FBG) is one of the key components in monolithic infrared fiber lasers and sensors. However, its effective fabrication using direct femtosecond laser writing is still seldom reported, owing to complications attributable to ChG. In this study, a double-D shaped ChG fiber was used to fabricate FBGs with high reflectivity (a 20.5 dB dip in the transmittance) and narrow 3-dB bandwidth (164 pm) using direct femtosecond laser writing. The high sensitivity to laser powers of the direct writing of the ChG FBG was revealed and understood from the perspective of the low laser-induced damage threshold of ChGs. Lower-order reflectance of the directly written FBGs at the mid-infrared wavelength region were quantitively predicted to have higher reflectivity. These results provide a robust method of writing FBGs with arbitrary periods in ChG fibers, establishing a solid foundation for the development of infrared fiber lasers and fiber sensors. © 2024 Elsevier Ltd
  Accession Number: 20240415438975
• Record 389 of
  
  Title:A truncated test scheme design method for success-failure in-orbit tests
  
  Author(s):Ding, Wenzhe(1,2); Bai, Xiang(1); Wang, Qingwei(1); Long, Fang(1); Li, Hailin(1); Wu, Zhengrong(1); Liu, Jian(1); Yao, Huisheng(1); Yang, Hong(1)
  Source: Reliability Engineering and System Safety  Volume: 243  Issue:   DOI: 10.1016/j.ress.2023.109782  Published: March 2024  
  Abstract:Based on the success-failure test feature of in-orbit tests (IOTs) for typical space equipment, this paper presents a method for designing a truncated test scheme for success-failure in-orbit tests. With this method, a small upper boundary of the sample size for the IOT verification test can be obtained before the test starts. The method introduces the truncated Bayes-sequential mesh test (SMT) method into the design of the IOT verification test scheme and greatly compresses the continuous test area by incorporating optimization theory, resulting in a smaller upper limit of the IOT sample size. First, this paper derives a specific calculation formula for the Bayes-SMT critical line. Second, the Markov chain model is adopted to calculate the occurrence probabilities of each acceptance and rejection point through state transition. Finally, an optimal truncated test optimization algorithm based on the augmented lagrangian genetic algorithm is proposed. Simulation tests show that, compared with the classical single sampling method, the truncated sequential probability ratio test method, the truncated SMT method, and the truncated Bayes-SMT method based on step-by-step calculation, the method presented in this paper can be used to obtain a sequential test scheme with smaller truncated sample size. © 2023
  Accession Number: 20234715092999
• Record 390 of
  
  Title:Stress-induced Polarization-Maintaining Large-mode-area Photonic Crystal Fibers with Deviation of the Single-mode Transmission Band and Delocalization of Higher-order Modes
  
  Author(s):Ma, Yuan(1); Wan, Rui(2); Yang, Huanhuan(1); Li, Yanfu(1); Chen, Chao(2); Wang, Pengfei(2)
  Source: IEEE Photonics Journal  Volume:   Issue:   DOI: 10.1109/JPHOT.2024.3395776  Published: 2024  
  Abstract:The nonlinear effects and laser-induced optical and thermal damage in optical fibers, together with the limitations of beam quality and mode-field area, restrict the power scaling-up of single-mode output for developing high-power fiber lasers in the kilowatt and above range. The design of photonic crystal fibers (PCFs) with large mode areas is an effective way to address this problem. In this paper, the demands and challenges of designing very large-mode-area (VLMA-) PCFs are discussed, including the overall fiber structure design and property simulation, especially the precise definition of single-mode operating conditions of VLMA-PCFs. Finally, an advanced stress-induced polarizationmaintaining, Yb-doped, PCF structure with a large mode area realized by introducing both leakage channels and higher order mode-filtering units is proposed and analyzed theoretically, for which a maximum core diameter of 101 μm and single-mode field diameter of 76.33 μm at 1064 nm and a birefringence value > 10−4 orders of magnitude are achieved. Authors
  Accession Number: 20241916047122
• Record 391 of
  
  Title:Design of Optical-mechanical System of Catadioptric Aerial Mapping Camera Based on Secondary Mirror Image Motion Compensation
  
  Author(s):Zhang, Hongwei(1); Qu, Rui(1); Chen, Weining(1); Yang, Hongtao(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 53  Issue: 2  DOI: 10.3788/gzxb20245302.0222001  Published: February 2024  
  Abstract:Aerial surveying and mapping is an important technical means of civil/military surveying and mapping，which can quickly obtain large-scale and high-precision scale mapping of the target area in a short period of time，and accurately obtain coordinate information of the target plane and elevation information on the map. The acquired information plays an important supporting role in digital city construction，land resources survey，military strategic planning，etc. With the development of aerial surveying and mapping technology，the requirements for aerial mapping cameras have been further improved. It is required that aerial mapping cameras can achieve wide width，high precision and large scale mapping. In order to meet the above requirements，the aerial mapping camera adopts scan imaging mode，but this imaging mechanism will introduce forward/scan image motion，which will affect the image quality. In order to satisfy the image stabilization accuracy of the aerial mapping camera，it is necessary to compensate the image motions. Therefore，a catadioptric aerial mapping camera based on secondary mirror image motion compensation is designed in this paper. Aiming at the dynamic image motion problem of the aerial mapping camera in the process of ground swing imaging，the vector aberration theory for a two-mirror telescopic systems is adopted. The secondary mirror is used as the image motion compensation element， and the comprehensive image motion compensation of the aerial mapping camera is realized through the secondary mirror multi-dimensional motion. However，in the process of compensating the image motion，the secondary mirror will be eccentric and inclined，which will cause the secondary mirror to be off-axis and affect the image quality. Therefore，a misalignment optical system model is established to study the relationship between the deviation vector of the secondary mirror field and the misalignment of the secondary mirror field，and the influence of the secondary mirror motion on the image quality is analyzed. Meanwhile，a design example of the optical-mechanical system of the catadioptric aerial mapping camera based on the secondary mirror image motion compensation is given. The effective focal length of the optical system is 450 mm，and the working spectrum is 435~900 nm. The field of view of the optical system is 4.17×3.13，and the F-number is 4.2. In the design process，the optical-mechanical system of aerial mapping camera adopts non-thermal design to adapt to the working environment of −40 ℃~60 ℃. In order to verify the image motion compensation ability of multi-dimensional motion of the optical element，an experimental platform is built to conduct laboratory imaging tests and field imaging tests on the aerial mapping camera. The laboratory imaging test results show that the dynamic resolution of the aerial mapping camera using the image motion compensation technology can reach 74 lp/mm，and the image motion compensation accuracy is better than 0.5 pixels，which meets the design expectation. In addition，the field imaging test results show that compared with disable image motion compensation function，the aerial survey camera with enable image motion compensation function can acquire sharp edges，clear images，and image quality can meet the expected requirements. Therefore，the camera has the advantages of high accuracy of image motion compensation，compact volume and high reliability，which lays a theoretical foundation for the direction of light and small，high precision and large scale mapping. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20240715561717
• Record 392 of
  
  Title:Blind deep-learning based preprocessing method for Fourier ptychographic microscopy
  
  Author(s):Wu, Kai(1,2); Pan, An(1); Sun, Zhonghan(1); Shi, Yinxia(1,2); Gao, Wei(1)
  Source: Optics and Laser Technology  Volume: 169  Issue:   DOI: 10.1016/j.optlastec.2023.110140  Published: February 2024  
  Abstract:Fourier ptychographic microscopy (FPM) is a technique for tackling the trade-off between the resolution and the imaging field of view by combining the techniques from aperture synthesis and phase retrieval to estimate the complex object from a series of low-resolution intensity images captured under angle-varied illumination. The captured images are commonly corrupted by multiple noise, leading to the degradation of the reconstructed image quality. Typically speaking, the noise model and noise level of the experimental images are unknown, and the traditional image denoising methods have limited effect. In this paper we model the FPM forward imaging process corrupted by noise and divide the noise in the captured images into two parts: the signal-dependent part and the signal-independent part. Based on the noise model we propose a novel blind deep-learning based Fourier ptychographic microscopy preprocessing method, termed BDFP, for removing these two components of noise. First, from a portion of the captured low-resolution images, a set of blocks corresponding to the smooth area of the object are extracted to model signal-independent noise. Second, under the assumption that the signal-dependent noise follows a Poisson distribution, we add Poisson noise and signal-independent noise blocks to clean images to form a paired training dataset, which is then used for training a deep convolutional neural network (CNN) model to reduce both signal-dependent noise and signal-independent noise. The proposed blind preprocessing method, combining with typical FPM reconstruction algorithms, is tested on simulated data and experimental images. Experimental results show that our preprocessing method can significantly reduce the noise in the captured images and bring about effective improvements in reconstructed image quality. © 2023 Elsevier Ltd
  Accession Number: 20234014830596
• Record 393 of
  
  Title:Fourier ptychographic reconstruction with denoising diffusion probabilistic models
  
  Author(s):Wu, Kai(1,2); Pan, An(1); Gao, Wei(1)
  Source: Optics and Laser Technology  Volume: 176  Issue:   DOI: 10.1016/j.optlastec.2024.111016  Published: September 2024  
  Abstract:Fourier ptychographic microscopy (FPM) is a promising computational imaging technique that can bypass the diffraction limit of the objective lens and achieve high-resolution, wide field-of-view imaging. The FPM setups firstly capture a series of low-resolution (LR) intensity images by angle-varied illumination and then reconstruction algorithms recover the high-resolution (HR) complex-valued object from the LR measurements. The image acquisition process commonly introduces noise, ultimately leading to degradation in the quality of the reconstruction results. In this paper, we report a noise-robust Fourier ptychographic reconstruction method that generates the HR complex-valued object estimation using the image priors specified by denoising diffusion probabilistic models (DDPM). First, the initial estimation of the HR complex-valued object is matched with an intermediate state in the Markov chain defined by DDPM. Then, the noisy initial solution is iteratively updated to a high-quality reconstruction result in the reverse process of DDPM and gradient descent correction is incorporated to enforce data consistency with the LR measurements. The proposed method integrates DDPM specified image priors and gradient descent correction, achieving solutions with less noise-related artifacts and high fidelity for HR complex-valued object estimation in Fourier ptychographic reconstruction. We apply the proposed method on both synthetic and real captured data. The experimental results show that our method can efficiently suppress the impact of noise and improve reconstruction results quality. © 2024 Elsevier Ltd
  Accession Number: 20241715963426
• Record 394 of
  
  Title:Dual Optical Target Recognition Method for Collimated Images Based on BLOB Region and Edge Feature Analysis
  
  Author(s):He, Wenxuan(1,2); Wang, Zhengzhou(1); Wei, Jitong(1); Wang, Li(1); Yi, Dongchi(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 53  Issue: 2  DOI: 10.3788/gzxb20245302.0210001  Published: February 2024  
  Abstract:In order to solve the problem that the collimated target recognition algorithm of optical path docking cannot distinguish the adhesive state of double targets，a new method of collimated image dual optical target recognition based on Binary Large Object（BLOB）region feature analysis is proposed. There are two optical targets in the optical alignment image，that is，the simulated optical target and the main laser target. In the initial beam control stage，the positions of the two optical targets are random and uncertain，and there is a possibility of the two optical targets sticking together，which causes great difficulties in beam control. Therefore，optical path alignment needs to solve the image recognition problem in two cases：1）In the initial beam control stage，when the main laser beam and the analog beam are just introduced，the adhesion recognition algorithm needs to be used to identify the adhesion state of the two optical targets. If the two optical targets are in the adhesion state，the two targets need to be completely separated by adjusting the 2D frame BM6XY motor；2） In the case of two optical targets completely separated，it is necessary to distinguish between the analog light target and main laser target in the two optical targets. Firstly，the binary image is processed by digital morphology to calculate the area，center Cxy，axis length lenxy and region Reginxy，of each BLOB region in the whole image. Secondly，the number of valid BLOB regions vblobcount is counted，and the distance between the two maximum connected domains dir is calculated. When vblobcount>1 and dir>100，the collimation image is the completely separated double target image，otherwise it is the adhered image. Then，for the completely separated dual-target image，the number of BLOBs located in the two largest BLOB regions with the center of each BLOB region is counted. The small number of candidate BLOB regions is the main laser target，and the large number of candidate BLOB regions is the analog light target. Finally，for the adhered image，when dir © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20240715561765
• Record 395 of
  
  Title:Temperature Measurement Method for Small Target Medium-Wave Infrared Spectral Radiation Based on Distance Correction
  
  Author(s):Li, Wen-Kai(1,2); Zhou, Liang(1); Liu, Zhao-Hui(1); Gui, Kai(1); Liu, Kai(1); Li, Zhi-Guo(1); Xie, Mei-Lin(1)
  Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis  Volume: 44  Issue: 4  DOI: 10.3964/j.issn.1000-0593(2024)04-1158-07  Published: April 2024  
  Abstract:For long-distance space targets moving at high speeds, temperature is one of the important parameters to characterize their working state and performance. Accurately obtaining the temperature of the target has an important reference value for judging its motion state and predicting its situation development. At present, the commonly used processing method of surface target or point target is no longer applicable to the measurement of the radiation characteristics of small targets. At the same time, spectral detection increases the distinguishable information of the target in the wavelength dimension, which can accurately obtain the distribution of the target energy with wavelength, providing a possibility for the inversion of the target temperature, and has great application potential. The slitless spectrometer can reduce the requirements for tracking and stabilization accuracy of space targets, has the characteristics of simple structure, high frame rate and fast response speed, and has high application value in astronomical observation and spacecraft observation. In this paper, we analyzed the spectral calibration model of target infrared radiation characteristic measurement and determined the main parameters in the linear response model of infrared detector pixels. In order to reduce the influence of imaging distance on temperature measurement accuracy, we proposed a target temperature inversion model based on distance correction. The improved temperature measurement accuracy meets the accuracy requirements in practical engineering applications and greatly affects infrared radiation spectrum temperature measurement. Certain guiding significance. © 2024 Science Press. All rights reserved.
  Accession Number: 20241515866101
• Record 396 of
  
  Title:An Infrared Evanescent Wave Sensor for Detection of Ascorbic Acid in Food and Drugs
  
  Author(s):You, Tianxiang(1); Zhao, Yongkun(1); Xu, Yantao(2); Guo, Haitao(2); Zhu, Jihong(3); Tao, Haizheng(1); Zhang, Xianghua(4); Xu, Yinsheng(1)
  Source: Journal of Lightwave Technology  Volume: 42  Issue: 9  DOI: 10.1109/JLT.2024.3357491  Published: May 1, 2024  
  Abstract:An infrared evanescent wave sensor was developed to accurately detect ascorbic acid (vitamin C) in food and drugs. The sensor was fabricated by tapering and bending of As2S3 infrared fibers. Due to the broad transmission range (5000-1500 cm-1) of the infrared fibers, covering the characteristic absorption peak of ascorbic acid (C = O at 1760 cm-1 and C = C at 1690 cm-1), the sensor is capable of accurately identifying and detecting the concentration of ascorbic acid. Experimental results demonstrated that a conically tapered fiber sensor with a waist diameter of 50 μm, waist length of 30 mm, and a radius of 2 mm achieved a maximum sensitivity of 0.1257 (a.u./(mg·ml-1)) and a limit of detection (LoD) of 0.917 mg/ml. Furthermore, the application of this fiber sensor in various vitamin C-containing tablets and juices validated its high accuracy and minimal measurement deviation (as low as 0.19 mg/ml). Compared to traditional detection methods, the sensor not only provides a faster and cost-effective solution to identify the substance but also maintains high accuracy. It offers a new approach to quantitative and qualitative analysis of food and drugs. © 1983-2012 IEEE.
  Accession Number: 20240615489260