Fu Gao, Zhengkai Li, Zhiyao Zhang, Heping Li, Yong Liu
An optimization method to improve the spurious free dynamic range (SFDR) of photonic sampling without sacrificing the signal-to-noise and distortion ratio (SINAD) is proposed and experimentally demonstrated. It is realized by managing the chirp in the generated ultrashort optical pulse train by simply changing the group velocity dispersion (GVD) of the dispersion compensation module (DCM) in the cavity-less ultra-short optical pulse source. In the simulation, the SFDRs of the photonic sampling for the input signals in the frequency range of 0.1 GHz to 40.1 GHz are significantly improved with residual linear chirp in the optical pulse train compared with the situation that the chirp is completely compensated. In the experiment, a 10.1 GHz single-tone microwave signal is sampled and the SFDR is improved by 10.95 dB owing to the residual chirp in the optical pulse train. In addition, the SINAD is improved by 2.76 dB even though the power of the fundamental frequency signal is slightly reduced. The proposed scheme can also be applied to photonic sampling ADCs based on other optical pulse sources, which is favorable for alleviating the limitation from the nonlinearity of the electro-optic amplitude modulator.
{"title":"Dynamic range enhancement of photonic sampling based on chirp management in cavity-less optical pulse source","authors":"Fu Gao, Zhengkai Li, Zhiyao Zhang, Heping Li, Yong Liu","doi":"10.1117/12.3006386","DOIUrl":"https://doi.org/10.1117/12.3006386","url":null,"abstract":"An optimization method to improve the spurious free dynamic range (SFDR) of photonic sampling without sacrificing the signal-to-noise and distortion ratio (SINAD) is proposed and experimentally demonstrated. It is realized by managing the chirp in the generated ultrashort optical pulse train by simply changing the group velocity dispersion (GVD) of the dispersion compensation module (DCM) in the cavity-less ultra-short optical pulse source. In the simulation, the SFDRs of the photonic sampling for the input signals in the frequency range of 0.1 GHz to 40.1 GHz are significantly improved with residual linear chirp in the optical pulse train compared with the situation that the chirp is completely compensated. In the experiment, a 10.1 GHz single-tone microwave signal is sampled and the SFDR is improved by 10.95 dB owing to the residual chirp in the optical pulse train. In addition, the SINAD is improved by 2.76 dB even though the power of the fundamental frequency signal is slightly reduced. The proposed scheme can also be applied to photonic sampling ADCs based on other optical pulse sources, which is favorable for alleviating the limitation from the nonlinearity of the electro-optic amplitude modulator.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138964496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Currently, China is still a major consumer of coal resources. Coal can be used in various fields such as industry and civil use, and can be used for power generation, heating, and building materials. There are many types of coal, each with its unique composition and properties. It has specific requirements for its use in various fields, which make the use of coal more reasonable and important for the sustainable development of the environment and resources. Therefore, the classification research of coal is of great significance. Due to the same component influence among various coals, there are certain challenges for coal classification. Therefore, a laser induced breakdown spectroscopy (LIBS) based on principal component analysis (PCA) combined with convolutional neural network (CNN) method was proposed to classify and recognize coal samples from six different regions. Through laser ablation of coal samples and collection of corresponding data, the data are dimensionalized and standardized, and then the spectral data are classified and trained through PCA-CNN optimization model. The final results indicate that the coal classification accuracy of the PCA-CNN deep learning network model can reach 98.15%. From this result class, it can be seen that laser induced breakdown spectroscopy technology combined with PCA-CNN can achieve rapid and accurate classification of coal samples from different regions, and provide a new coal quality detection data analysis and processing scheme.
{"title":"Classification of different coals using laser induced breakdown spectroscopy (LIBS) combined with PCA-CNN","authors":"Shuaijun Li, Xiaojian Hao, Biming Mo, Junjie Chen, Haoyu Jin, Xiaodong Liang","doi":"10.1117/12.3003983","DOIUrl":"https://doi.org/10.1117/12.3003983","url":null,"abstract":"Currently, China is still a major consumer of coal resources. Coal can be used in various fields such as industry and civil use, and can be used for power generation, heating, and building materials. There are many types of coal, each with its unique composition and properties. It has specific requirements for its use in various fields, which make the use of coal more reasonable and important for the sustainable development of the environment and resources. Therefore, the classification research of coal is of great significance. Due to the same component influence among various coals, there are certain challenges for coal classification. Therefore, a laser induced breakdown spectroscopy (LIBS) based on principal component analysis (PCA) combined with convolutional neural network (CNN) method was proposed to classify and recognize coal samples from six different regions. Through laser ablation of coal samples and collection of corresponding data, the data are dimensionalized and standardized, and then the spectral data are classified and trained through PCA-CNN optimization model. The final results indicate that the coal classification accuracy of the PCA-CNN deep learning network model can reach 98.15%. From this result class, it can be seen that laser induced breakdown spectroscopy technology combined with PCA-CNN can achieve rapid and accurate classification of coal samples from different regions, and provide a new coal quality detection data analysis and processing scheme.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138964971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gaojian Liu, Qinggui Tan, Okky Daulay, Kaixuan Ye, Xiangke Deng, Feiteng Zheng, Hongxi Yu, David Marpaung
In this paper, we reviewed and presented our latest progress of linearization methods for microwave photonic systems based on programmable photonic circuits, including the linearization in microwave photonic transmission links and programmable functional circuits.
{"title":"Research progress of on-chip linearization methods for microwave photonic systems","authors":"Gaojian Liu, Qinggui Tan, Okky Daulay, Kaixuan Ye, Xiangke Deng, Feiteng Zheng, Hongxi Yu, David Marpaung","doi":"10.1117/12.3008150","DOIUrl":"https://doi.org/10.1117/12.3008150","url":null,"abstract":"In this paper, we reviewed and presented our latest progress of linearization methods for microwave photonic systems based on programmable photonic circuits, including the linearization in microwave photonic transmission links and programmable functional circuits.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138965169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Weichao Ma, Ruixuan Wang, Jianwei Liu, Chenyu Liu, Wangzhe Li
A multi-functional microwave photonic circuit with meshed architecture is designed and demonstrated on thin film lithium niobate platform. Taking the advantages of the fast response of the Pockels effect and optimized device design, the operation bandwidth of the chip exceeds 60GHz. By controlling the transmission paths of the photon at each node, the on-chip device resources are configurated as a variety of microwave links, corresponding to different signal processing functions. The capabilities of signal generation, down-conversion mixing with high dynamic range and self-interference cancellation with high suppression ratio are experimentally demonstrated. For signal generation, the chip can be regarded as a frequency doubler, and both linear and nonlinear frequency modulated waveforms are obtained with a time-bandwidth product of 2×105 and an in-band spurious suppression ratio higher than 40dB. When configurated as a mixer, the chip achieves a spurious free dynamic range of 105 dB/Hz2/3 and a down-conversion efficiency of -7.4dB. The lithium niobate avoids the nonlinear carrier transportation and absorption existing in traditional silicon photonics, breaking the limitation of linearity and efficiency. As self-interference cancellation mode is set, the interference is suppressed by 50dB over 1.1GHz span. The uniformity of microfabrication in combination with the precise adjustment of the amplitude and phase of the optical field guarantees the high cancellation ratio. To the best of our knowledge, this photonic chip possesses the largest bandwidth and excellent comprehensive performance in terms of active signal processing among integrated multifunctional microwave photonic circuits.
{"title":"Multi-functional microwave photonic circuit based on thin film lithium niobate platform","authors":"Weichao Ma, Ruixuan Wang, Jianwei Liu, Chenyu Liu, Wangzhe Li","doi":"10.1117/12.3008119","DOIUrl":"https://doi.org/10.1117/12.3008119","url":null,"abstract":"A multi-functional microwave photonic circuit with meshed architecture is designed and demonstrated on thin film lithium niobate platform. Taking the advantages of the fast response of the Pockels effect and optimized device design, the operation bandwidth of the chip exceeds 60GHz. By controlling the transmission paths of the photon at each node, the on-chip device resources are configurated as a variety of microwave links, corresponding to different signal processing functions. The capabilities of signal generation, down-conversion mixing with high dynamic range and self-interference cancellation with high suppression ratio are experimentally demonstrated. For signal generation, the chip can be regarded as a frequency doubler, and both linear and nonlinear frequency modulated waveforms are obtained with a time-bandwidth product of 2×105 and an in-band spurious suppression ratio higher than 40dB. When configurated as a mixer, the chip achieves a spurious free dynamic range of 105 dB/Hz2/3 and a down-conversion efficiency of -7.4dB. The lithium niobate avoids the nonlinear carrier transportation and absorption existing in traditional silicon photonics, breaking the limitation of linearity and efficiency. As self-interference cancellation mode is set, the interference is suppressed by 50dB over 1.1GHz span. The uniformity of microfabrication in combination with the precise adjustment of the amplitude and phase of the optical field guarantees the high cancellation ratio. To the best of our knowledge, this photonic chip possesses the largest bandwidth and excellent comprehensive performance in terms of active signal processing among integrated multifunctional microwave photonic circuits.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138965236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Infrared polarization technology is generally applied in object detection and analysis. However, chromatic aberration restricted the development of Infrared polarization detectors. Metalenses are two-dimensional artificial electromagnetic materials to balance chromatic aberration and an ideal platform for miniaturization and integration of infrared polarization technology. In this paper, a fully polarized detection of mid-infrared achromatic metalens is designed, with a single metalens unit diameter of 30μm, a focal length of 15μm, and a working wavelength of 3μm-5μm. Through FDTD software simulation, the results show that the metalens focuses at focal plane for any polarized state light throughout the working wavelength band, with a full width at half maximum (FWHM) of the peak of less than 6&μm, achieving achromaticity. The maximum aspect ratio of the nanopillar is 15:1, meeting the requirements of electron beam lithography processing. The designed metalens achieves full-polarization detection a wider working wavelength band comparing with existing polarization detection devices, which indicates a potential application value for mid-infrared polarization detection and imaging technology.
{"title":"Fully polarized detection of mid-infrared broadband achromatic metalenses","authors":"Xingwei Liu, Guoguo Kang, Lingxue Wang","doi":"10.1117/12.3005355","DOIUrl":"https://doi.org/10.1117/12.3005355","url":null,"abstract":"Infrared polarization technology is generally applied in object detection and analysis. However, chromatic aberration restricted the development of Infrared polarization detectors. Metalenses are two-dimensional artificial electromagnetic materials to balance chromatic aberration and an ideal platform for miniaturization and integration of infrared polarization technology. In this paper, a fully polarized detection of mid-infrared achromatic metalens is designed, with a single metalens unit diameter of 30μm, a focal length of 15μm, and a working wavelength of 3μm-5μm. Through FDTD software simulation, the results show that the metalens focuses at focal plane for any polarized state light throughout the working wavelength band, with a full width at half maximum (FWHM) of the peak of less than 6&μm, achieving achromaticity. The maximum aspect ratio of the nanopillar is 15:1, meeting the requirements of electron beam lithography processing. The designed metalens achieves full-polarization detection a wider working wavelength band comparing with existing polarization detection devices, which indicates a potential application value for mid-infrared polarization detection and imaging technology.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138965247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lv Wang, Jun-hu Xie, Hongliang Cheng, Yan-ling luo, Fang Liu, Meng Gao, Hemin Meng, Nan Wang, Xicheng Wang, Man Wang
In order to meet the needs of counter photoelectric detection and precision guidance weapons in modern air warfare, the spectral characteristics of smoke image jamming unit were tested. Based on the analysis of the factors affecting the smoke interference performance, a theoretical calculation model is established, and a feasible test method is proposed. A certain type of smoke jamming unit was tested. We obtained the smoke transmittance curveof0.4-0.76um,1.3-3um,3-5um,8-14um and MWIR and LWIR image of typical time period, which laid a foundation for the further development of smoke jamming unit with better performance.
{"title":"Study on spectral characteristics of smoke interference unit","authors":"Lv Wang, Jun-hu Xie, Hongliang Cheng, Yan-ling luo, Fang Liu, Meng Gao, Hemin Meng, Nan Wang, Xicheng Wang, Man Wang","doi":"10.1117/12.3008480","DOIUrl":"https://doi.org/10.1117/12.3008480","url":null,"abstract":"In order to meet the needs of counter photoelectric detection and precision guidance weapons in modern air warfare, the spectral characteristics of smoke image jamming unit were tested. Based on the analysis of the factors affecting the smoke interference performance, a theoretical calculation model is established, and a feasible test method is proposed. A certain type of smoke jamming unit was tested. We obtained the smoke transmittance curveof0.4-0.76um,1.3-3um,3-5um,8-14um and MWIR and LWIR image of typical time period, which laid a foundation for the further development of smoke jamming unit with better performance.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138994680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An improvement project for LAMOST is to be implemented soon. In order to reduce the heat generation of the drive system and improve the observation accuracy. In this paper, an ultra-low power drive system for an integrated fiber positioner robot is designed, and its hardware drive circuit and low-power software driver are described in detail. Each module in the hardware driver circuit is designed with its size and power consumption in mind, and the driver board is powered by time-sharing and partitioning. A task scheduling mechanism based on STM32 low-power mode is designed in the software driver of the fiber positioner robot, which analyzes the idle state between tasks when it receives a control command task, and selectively enters the low-power mode after executing the drive task in each round. In order to evaluate the low-power characteristics of this ultra-low power drive system, we built a power consumption measurement platform. The experimental results show that the static power supply current of each driver board in this designed ultra-low power driver system is 16.20mA, and its static power consumption is reduced by 92.50% compared with the previous generation of fiber positioner robot driver boards.
{"title":"Ultra-low power drive system design for fiber positioner robot","authors":"Mengjie Zhu, Zhen Zhang, Chao Zhai","doi":"10.1117/12.3005245","DOIUrl":"https://doi.org/10.1117/12.3005245","url":null,"abstract":"An improvement project for LAMOST is to be implemented soon. In order to reduce the heat generation of the drive system and improve the observation accuracy. In this paper, an ultra-low power drive system for an integrated fiber positioner robot is designed, and its hardware drive circuit and low-power software driver are described in detail. Each module in the hardware driver circuit is designed with its size and power consumption in mind, and the driver board is powered by time-sharing and partitioning. A task scheduling mechanism based on STM32 low-power mode is designed in the software driver of the fiber positioner robot, which analyzes the idle state between tasks when it receives a control command task, and selectively enters the low-power mode after executing the drive task in each round. In order to evaluate the low-power characteristics of this ultra-low power drive system, we built a power consumption measurement platform. The experimental results show that the static power supply current of each driver board in this designed ultra-low power driver system is 16.20mA, and its static power consumption is reduced by 92.50% compared with the previous generation of fiber positioner robot driver boards.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138994946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose a high-order microring filter structure based on the Silicon-On-Insulator (SOI) platform for flattening filtering. This filter structure can achieve a box-like spectral response with large free-spectral-range (FSR) and high out-of-band extinction ratio (ER), which can be widely used in various fields, especially in the wavelength division multiplexing. The filter consists of two or more rings which are connected in series, with Ti electrodes added on them for thermal tuning. According to the proposed requirements of spectral bandwidth and FSR, the physical dimensions of the high-order microring filter structure can be calculated based on theoretical formulas, and we optimize them for better performance. The relationship of the coupling coefficients of each coupling zone is calculated based on the Butterworth spectral responses. Result shows that the higher-order filter has steeper rise-fall edges and a flatter top, and can be designed to achieve a larger FSR. The FSR of the fourth-order microring filter can be designed to 78.4 nm, with ER of 12.6 dB, and the insertion loss of 1.1 dB. The fluctuations at the top of the box-like spectra caused by the fabrication deviations can be compensated by applying voltages to Ti electrodes, which can change the effective refractive index of the waveguide.
{"title":"Thermally tunable high-order microring filters with large free-spectral-range","authors":"Jiamei Gu, Zhaoyu Wang, Xin Chen, Xiao Ma, Mingyu Li, Jianjun He","doi":"10.1117/12.3000512","DOIUrl":"https://doi.org/10.1117/12.3000512","url":null,"abstract":"We propose a high-order microring filter structure based on the Silicon-On-Insulator (SOI) platform for flattening filtering. This filter structure can achieve a box-like spectral response with large free-spectral-range (FSR) and high out-of-band extinction ratio (ER), which can be widely used in various fields, especially in the wavelength division multiplexing. The filter consists of two or more rings which are connected in series, with Ti electrodes added on them for thermal tuning. According to the proposed requirements of spectral bandwidth and FSR, the physical dimensions of the high-order microring filter structure can be calculated based on theoretical formulas, and we optimize them for better performance. The relationship of the coupling coefficients of each coupling zone is calculated based on the Butterworth spectral responses. Result shows that the higher-order filter has steeper rise-fall edges and a flatter top, and can be designed to achieve a larger FSR. The FSR of the fourth-order microring filter can be designed to 78.4 nm, with ER of 12.6 dB, and the insertion loss of 1.1 dB. The fluctuations at the top of the box-like spectra caused by the fabrication deviations can be compensated by applying voltages to Ti electrodes, which can change the effective refractive index of the waveguide.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138995064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuebo Liu, YiXiong Huang, Wenyuan Liao, Hao Niu, Jiahui Yan, Shaohua Yang, Teng Ma, HongYue Wang, C. Lai
The waveguide branch plays an important role in integrated photonic circuits by dividing input light into two or more output lights, thereby facilitating optical power distribution and mode selection. Ordinary optical waveguides used in waveguide branches suffer from excessive optical loss and narrow branch angles, limiting their effectiveness in mode selection among other problems. Photonic crystals are constructed by arranging macroscopically homogeneous dielectric (or metallic) materials into periodic arrays, with carefully designed internal defects that provide them with frequency-selective and spatial properties. In this study, a silicon-based wide-angle waveguide branch composed of two-dimensional photonic crystals has been successfully created. The branch is capable of separating two wavelengths of light, namely 850 nm and 950 nm, by adjusting the positions of silicon cylinders in the two-dimensional photonic crystal with the purpose of optimizing optical power at different wavelengths. The silicon-based wide-angle waveguide branch is expected to be employed in multimode optical communication systems. Its utilization will contribute towards the reduction in size and complexity of integrated optical communication systems, while enhancing system reliability.
{"title":"Two-dimensional Si photonic crystal waveguide branch for 850 nm and 950 nm wavelengths","authors":"Yuebo Liu, YiXiong Huang, Wenyuan Liao, Hao Niu, Jiahui Yan, Shaohua Yang, Teng Ma, HongYue Wang, C. Lai","doi":"10.1117/12.3005928","DOIUrl":"https://doi.org/10.1117/12.3005928","url":null,"abstract":"The waveguide branch plays an important role in integrated photonic circuits by dividing input light into two or more output lights, thereby facilitating optical power distribution and mode selection. Ordinary optical waveguides used in waveguide branches suffer from excessive optical loss and narrow branch angles, limiting their effectiveness in mode selection among other problems. Photonic crystals are constructed by arranging macroscopically homogeneous dielectric (or metallic) materials into periodic arrays, with carefully designed internal defects that provide them with frequency-selective and spatial properties. In this study, a silicon-based wide-angle waveguide branch composed of two-dimensional photonic crystals has been successfully created. The branch is capable of separating two wavelengths of light, namely 850 nm and 950 nm, by adjusting the positions of silicon cylinders in the two-dimensional photonic crystal with the purpose of optimizing optical power at different wavelengths. The silicon-based wide-angle waveguide branch is expected to be employed in multimode optical communication systems. Its utilization will contribute towards the reduction in size and complexity of integrated optical communication systems, while enhancing system reliability.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138995233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The high-power picosecond laser systems have been used in many fields, such as materials dynamics research, cancer treatment, and high spatial and temporal resolution backlight radiography[1] . Compared to nanosecond laser, picosecond laser with higher peak intensity can generate more serious fast nonlinear growth, which leads to the small-scale autofocusing (SSSF) effect and the beam splitting into filament, affecting the safe operation of the laser system and limiting its output capability. How to effectively suppress the fast nonlinear growth and improve the near-field quality of the output beam in picosecond laser systems has become a hot topic of interest. In recent years, a band-stop filtering technology based on volume Bragg gratings (VBGs) has been proposed, which can effectively filter out the specific medium-high frequencies (MHFs) of the beam and suppress the SSSF effect. In this paper, a filter based on the composition of two VBGs is designed to take advantage of the excellent angular selectivity of the VBG. The incident angle of the incident beam is matched with the first diffraction zero point of VBGs to constitute a band-stop angular filter (BSF). Combined with the picosecond laser amplification system, the ability of BSF to suppress the fast nonlinear growth generated is investigated. The near-field distribution of the beam through is numerically simulated. This method proposed in this paper effectively suppresses the SSSF effect of the beam in high-power laser systems and provides a new technical approach for picosecond laser amplification.
{"title":"The control of fast nonlinear growth in picosecond laser","authors":"Honggang Zheng, Xiang Zhang, Xiao Yuan","doi":"10.1117/12.2692233","DOIUrl":"https://doi.org/10.1117/12.2692233","url":null,"abstract":"The high-power picosecond laser systems have been used in many fields, such as materials dynamics research, cancer treatment, and high spatial and temporal resolution backlight radiography[1] . Compared to nanosecond laser, picosecond laser with higher peak intensity can generate more serious fast nonlinear growth, which leads to the small-scale autofocusing (SSSF) effect and the beam splitting into filament, affecting the safe operation of the laser system and limiting its output capability. How to effectively suppress the fast nonlinear growth and improve the near-field quality of the output beam in picosecond laser systems has become a hot topic of interest. In recent years, a band-stop filtering technology based on volume Bragg gratings (VBGs) has been proposed, which can effectively filter out the specific medium-high frequencies (MHFs) of the beam and suppress the SSSF effect. In this paper, a filter based on the composition of two VBGs is designed to take advantage of the excellent angular selectivity of the VBG. The incident angle of the incident beam is matched with the first diffraction zero point of VBGs to constitute a band-stop angular filter (BSF). Combined with the picosecond laser amplification system, the ability of BSF to suppress the fast nonlinear growth generated is investigated. The near-field distribution of the beam through is numerically simulated. This method proposed in this paper effectively suppresses the SSSF effect of the beam in high-power laser systems and provides a new technical approach for picosecond laser amplification.","PeriodicalId":298662,"journal":{"name":"Applied Optics and Photonics China","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138995292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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