Journals > > Topics > Special Issue on 70th anniversary of National University of Defense Technology
Special Issue on 70th anniversary of National University of Defense Technology|8 Article(s)
Single-pixel wavefront sensing via vectorial polarization modulation [Invited]|On the Cover
Wunan Li, Yu Cao, Yu Ning, Fengjie Xi, Quan Sun, and Xiaojun Xu
The Shack–Hartmann wavefront sensor (SHWFS) is commonly used for its high speed and precision in adaptive optics. However, its performance is limited in low light conditions, particularly when observing faint objects in astronomical applications. Instead of a pixelated detector, we present a new approach for wavefront sensing using a single-pixel detector, which is able to code the spatial position of a light spot array into the polarization dimension and decode the polarization state in the polar coordinate. We propose validation experiments with simple and complex wavefront distortions to demonstrate our approach as a promising alternative to traditional SHWFS systems, with potential applications in a wide range of fields. The Shack–Hartmann wavefront sensor (SHWFS) is commonly used for its high speed and precision in adaptive optics. However, its performance is limited in low light conditions, particularly when observing faint objects in astronomical applications. Instead of a pixelated detector, we present a new approach for wavefront sensing using a single-pixel detector, which is able to code the spatial position of a light spot array into the polarization dimension and decode the polarization state in the polar coordinate. We propose validation experiments with simple and complex wavefront distortions to demonstrate our approach as a promising alternative to traditional SHWFS systems, with potential applications in a wide range of fields.
Chinese Optics Letters
- Publication Date: Sep. 19, 2023
- Vol. 21, Issue 9, 090008 (2023)
Recent advances in optical fiber high-temperature sensors and encapsulation technique [Invited]
Wenjie Xu, Qiang Bian, Jianqiao Liang, Zhencheng Wang, Yang Yu, and Zhou Meng
In the aerospace field, for aerospace engines and other high-end manufacturing equipment working in extreme environments, like ultrahigh temperatures, high pressure, and high-speed airflow, in situ temperature measurement is of great importance for improving the structure design and achieving the health monitoring and the fault diagnosis of critical parts. Optical fiber sensors have the advantages of small size, easy design, corrosion resistance, anti-electromagnetic interference, and the ability to achieve distributed or quasi-distributed sensing and have broad application prospects for temperature sensing in extreme environments. In this review, first, we introduce the current research status of fiber Bragg grating-type and Fabry–Perot interferometer-type high-temperature sensors. Then we review the optical fiber high-temperature sensor encapsulation techniques, including tubular encapsulation, substrate encapsulation, and metal-embedded encapsulation, and discuss the extreme environmental adaptability of different encapsulation structures. Finally, the critical technological issues that need to be solved for the application of optical fiber sensors in extreme environments are discussed. In the aerospace field, for aerospace engines and other high-end manufacturing equipment working in extreme environments, like ultrahigh temperatures, high pressure, and high-speed airflow, in situ temperature measurement is of great importance for improving the structure design and achieving the health monitoring and the fault diagnosis of critical parts. Optical fiber sensors have the advantages of small size, easy design, corrosion resistance, anti-electromagnetic interference, and the ability to achieve distributed or quasi-distributed sensing and have broad application prospects for temperature sensing in extreme environments. In this review, first, we introduce the current research status of fiber Bragg grating-type and Fabry–Perot interferometer-type high-temperature sensors. Then we review the optical fiber high-temperature sensor encapsulation techniques, including tubular encapsulation, substrate encapsulation, and metal-embedded encapsulation, and discuss the extreme environmental adaptability of different encapsulation structures. Finally, the critical technological issues that need to be solved for the application of optical fiber sensors in extreme environments are discussed.
Chinese Optics Letters
- Publication Date: Sep. 21, 2023
- Vol. 21, Issue 9, 090007 (2023)
Comparison of optical properties of bioaerosols composed of microbial spores and hyphae [Invited]
Xinyu Wang, Yihua Hu, Xing Yang, Youlin Gu, Haihao He, Wanying Ding, and Peng Wang
Bioaerosols exhibit significant broadband extinction performance and have vital impacts on climate change, optical detection, communication, disease transmission, and the development of optical attenuation materials. Microbial spores and microbial hyphae represent two primary forms of bioaerosol particles. However, a comprehensive investigation and comparison of their optical properties have not been conducted yet. In this paper, the spectra of spores and hyphae were tested, and the absorption peaks, component contents, and protein structural differences were compared. Accurate structural models were established, and the optical attenuation parameters were calculated. Aerosol chamber experiments were conducted to verify the optical attenuation performance of microbial spores and hyphae in the mid-infrared and far-infrared spectral bands. Results demonstrate that selecting spores and hyphae can significantly reduce the average transmittance from 21.2% to 6.4% in the mid-infrared band and from 31.3% to 19.6% in the far-infrared band within three minutes. The conclusions have significant implications for the selection of high-performance microbial optical attenuation materials as well as for the rapid detection of bioaerosol types in research on climate change and the spread of pathogenic aerosols. Bioaerosols exhibit significant broadband extinction performance and have vital impacts on climate change, optical detection, communication, disease transmission, and the development of optical attenuation materials. Microbial spores and microbial hyphae represent two primary forms of bioaerosol particles. However, a comprehensive investigation and comparison of their optical properties have not been conducted yet. In this paper, the spectra of spores and hyphae were tested, and the absorption peaks, component contents, and protein structural differences were compared. Accurate structural models were established, and the optical attenuation parameters were calculated. Aerosol chamber experiments were conducted to verify the optical attenuation performance of microbial spores and hyphae in the mid-infrared and far-infrared spectral bands. Results demonstrate that selecting spores and hyphae can significantly reduce the average transmittance from 21.2% to 6.4% in the mid-infrared band and from 31.3% to 19.6% in the far-infrared band within three minutes. The conclusions have significant implications for the selection of high-performance microbial optical attenuation materials as well as for the rapid detection of bioaerosol types in research on climate change and the spread of pathogenic aerosols.
Chinese Optics Letters
- Publication Date: Sep. 15, 2023
- Vol. 21, Issue 9, 090006 (2023)
Water track laser Doppler velocimeter [Invited]
Rong Huang, Qi Wang, Zhiyi Xiang, Xiaoming Nie, Jian Zhou, and Hui Luo
A water track laser Doppler velocimeter (LDV) is developed with advantages of high update rate, high real-time performance, high concealment, light weight, and small dimensions. The water track LDV measures the advance velocity of the underwater vehicle with respect to the surrounding water. The experimental results show that the water track LDV has an accuracy of 96.4% when the moving velocity of the vehicle with respect to the ground exceeds 0.25 m/s. Thus, the water track LDV is promising in the application of underwater navigation to aid the strapdown inertial navigation system. A water track laser Doppler velocimeter (LDV) is developed with advantages of high update rate, high real-time performance, high concealment, light weight, and small dimensions. The water track LDV measures the advance velocity of the underwater vehicle with respect to the surrounding water. The experimental results show that the water track LDV has an accuracy of 96.4% when the moving velocity of the vehicle with respect to the ground exceeds 0.25 m/s. Thus, the water track LDV is promising in the application of underwater navigation to aid the strapdown inertial navigation system.
Chinese Optics Letters
- Publication Date: Sep. 15, 2023
- Vol. 21, Issue 9, 090005 (2023)
2 kW random fiber laser based on hybrid Yb-Raman gain [Invited]|Editors' Pick
Jun Ye, Yang Zhang, Junrui Liang, Xiaoya Ma, Jiangming Xu, Tianfu Yao, Jinyong Leng, and Pu Zhou
High-power operation is one of the most important research topics surrounding random fiber lasers (RDFLs). Here we optimized the cavity structure and proposed a new scheme based on hybrid gain to address the issue of high-power backward light in traditional kilowatt-level RDFLs. Consequently, a record power of 1972 W was achieved while the maximum backward leaked power only reached 0.12 W. The conversion efficiency relative to the laser diode pump power was 68.4%, and the highest spectral purity of the random lasing reached 98.1%. This work may provide a reference for high-power RDFLs, Raman fiber lasers, and long-wavelength Yb-doped fiber lasers. High-power operation is one of the most important research topics surrounding random fiber lasers (RDFLs). Here we optimized the cavity structure and proposed a new scheme based on hybrid gain to address the issue of high-power backward light in traditional kilowatt-level RDFLs. Consequently, a record power of 1972 W was achieved while the maximum backward leaked power only reached 0.12 W. The conversion efficiency relative to the laser diode pump power was 68.4%, and the highest spectral purity of the random lasing reached 98.1%. This work may provide a reference for high-power RDFLs, Raman fiber lasers, and long-wavelength Yb-doped fiber lasers.
Chinese Optics Letters
- Publication Date: Aug. 18, 2023
- Vol. 21, Issue 9, 090004 (2023)
Analysis of extinction characteristics of non-spherical biological particle aggregates [Invited]
Guolong Chen, Youlin Gu, Yihua Hu, Fanhao Meng, Wanying Ding, and Xi Zhang
In this study, a method was presented to accurately obtain the extinction characteristics of the non-spherical biological particle aggregates. Based on the multi-sphere particle model of non-spherical particles, a randomly oriented aggregation model was firstly built to construct the aggregates. The discrete-dipole approximation method was used to calculate the extinction characteristics of aggregates in the 3–14 µm waveband. The average mass extinction coefficients of three materials are 0.802 m2/g, 0.907 m2/g, and 0.866 m2/g in the 3–5 µm waveband and 0.590 m2/g, 0.402 m2/g, and 0.523 m2/g in the 8–14 µm band, respectively. Smoke chamber experimental results are in good agreement with theoretical analyses. In this study, a method was presented to accurately obtain the extinction characteristics of the non-spherical biological particle aggregates. Based on the multi-sphere particle model of non-spherical particles, a randomly oriented aggregation model was firstly built to construct the aggregates. The discrete-dipole approximation method was used to calculate the extinction characteristics of aggregates in the 3–14 µm waveband. The average mass extinction coefficients of three materials are 0.802 m2/g, 0.907 m2/g, and 0.866 m2/g in the 3–5 µm waveband and 0.590 m2/g, 0.402 m2/g, and 0.523 m2/g in the 8–14 µm band, respectively. Smoke chamber experimental results are in good agreement with theoretical analyses.
Chinese Optics Letters
- Publication Date: Aug. 23, 2023
- Vol. 21, Issue 9, 090003 (2023)
High-power single-frequency fiber amplifiers: progress and challenge [Invited]
Can Li, Yue Tao, Man Jiang, Pengfei Ma, Wei Liu, Rongtao Su, Jiangming Xu, Jinyong Leng, and Pu Zhou
Unlike conventional continuous-wave lasers with wide spectra, the amplification of single-frequency lasers in optical fibers is much more difficult owing to the ultra-high power spectral density induced nonlinear stimulated Brillouin scattering effect. Nevertheless, over the past two decades much effort has been devoted to improving the power scaling and performance of high-power single-frequency fiber amplifiers. These amplifiers are mostly driven by applications, such as high precision detection and metrology, and have benefited from the long coherence length, low noise, and excellent beam quality of this type of laser source. In this paper, we review the overall development of high-power single-frequency fiber amplifiers by focusing on its progress and challenges, specifically, the strategies for circumventing the stimulated Brillouin scattering and transverse mode instability effects that, at present, are the major limiting factors of the power scaling of the single-frequency fiber amplifiers. These factors are also thoroughly discussed in terms of free-space and all-fiber coupled architecture. In addition, we also examine the noise properties of single-frequency fiber amplifiers, along with corresponding noise reducing schemes. Finally, we briefly envision the future development of high-power single-frequency fiber amplifiers. Unlike conventional continuous-wave lasers with wide spectra, the amplification of single-frequency lasers in optical fibers is much more difficult owing to the ultra-high power spectral density induced nonlinear stimulated Brillouin scattering effect. Nevertheless, over the past two decades much effort has been devoted to improving the power scaling and performance of high-power single-frequency fiber amplifiers. These amplifiers are mostly driven by applications, such as high precision detection and metrology, and have benefited from the long coherence length, low noise, and excellent beam quality of this type of laser source. In this paper, we review the overall development of high-power single-frequency fiber amplifiers by focusing on its progress and challenges, specifically, the strategies for circumventing the stimulated Brillouin scattering and transverse mode instability effects that, at present, are the major limiting factors of the power scaling of the single-frequency fiber amplifiers. These factors are also thoroughly discussed in terms of free-space and all-fiber coupled architecture. In addition, we also examine the noise properties of single-frequency fiber amplifiers, along with corresponding noise reducing schemes. Finally, we briefly envision the future development of high-power single-frequency fiber amplifiers.
Chinese Optics Letters
- Publication Date: Aug. 14, 2023
- Vol. 21, Issue 9, 090002 (2023)
Adaptive microwave photonic angle-of-arrival estimation based on BiGRU-CNN [Invited]
Yin Li, Qiaosong Cai, Jie Yang, Tong Zhou, Yuanxi Peng, and Tian Jiang
An adaptive microwave photonic angle-of-arrival (AOA) estimation approach based on a convolutional neural network with a bidirectional gated recurrent unit (BiGRU-CNN) is proposed and demonstrated. Compared with the previously reported AOA estimation methods based on phase-to-power mapping, the proposed method is unnecessary to know the frequency of the signal under test (SUT) in advance. The envelope voltage correlation matrix is obtained from dual-drive Mach–Zehnder modulator (N-DDMZM, N > 2) optical interferometer arrays first, and then AOA estimations are performed on different frequency signals with the aid of BiGRU-CNN. A three-DDMZM-based experiment is carried out to assess the estimation performance of microwave signals at three different frequencies, and the mean absolute error is only 0.1545°. An adaptive microwave photonic angle-of-arrival (AOA) estimation approach based on a convolutional neural network with a bidirectional gated recurrent unit (BiGRU-CNN) is proposed and demonstrated. Compared with the previously reported AOA estimation methods based on phase-to-power mapping, the proposed method is unnecessary to know the frequency of the signal under test (SUT) in advance. The envelope voltage correlation matrix is obtained from dual-drive Mach–Zehnder modulator (N-DDMZM, N > 2) optical interferometer arrays first, and then AOA estimations are performed on different frequency signals with the aid of BiGRU-CNN. A three-DDMZM-based experiment is carried out to assess the estimation performance of microwave signals at three different frequencies, and the mean absolute error is only 0.1545°.
Chinese Optics Letters
- Publication Date: Sep. 15, 2023
- Vol. 21, Issue 9, 090001 (2023)
Topics
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20