A novel scheme for frequency-modulated continuous-wave (FMCW) laser generation, based on electro-optic modulation and sideband injection locking, is proposed and experimentally demonstrated. By exploiting the nonlinear characteristics of a Mach–Zehnder modulator together with the selective amplification enabled by injection locking, the optical carrier energy is efficiently transferred to the positive second-order modulation sideband. As a result, carrier-suppressed single-sideband FMCW modulation with doubled bandwidth is achieved. This bandwidth enhancement significantly improves the range resolution of FMCW LiDAR. Experimental results show that the proposed FMCW laser scheme achieves a wide frequency bandwidth of 6 GHz, a residual nonlinearity as low as $10.3boldsymbol {times } 10{^{text {-5}}}$ , and a fast chirp rate of 2.4 GHz/$upmu $ s. Additionally, the feasibility of LiDAR ranging based on the proposed FMCW laser scheme was demonstrated. The LiDAR system exhibits a range resolution of 2.5 cm, matching the theoretical value. Notably, the proposed scheme eliminates the need for complex modulators, optical filters, and optical amplifiers, while reducing the required electronic bandwidth, thereby facilitating a significant reduction in system cost.
{"title":"Generation of a Frequency-Modulated Continuous-Wave Laser via Sideband Injection Locking for LiDAR","authors":"Renheng Zhang;Kunpeng Zhai;Wenting Wang;Ninghua Zhu","doi":"10.1109/LPT.2025.3645179","DOIUrl":"https://doi.org/10.1109/LPT.2025.3645179","url":null,"abstract":"A novel scheme for frequency-modulated continuous-wave (FMCW) laser generation, based on electro-optic modulation and sideband injection locking, is proposed and experimentally demonstrated. By exploiting the nonlinear characteristics of a Mach–Zehnder modulator together with the selective amplification enabled by injection locking, the optical carrier energy is efficiently transferred to the positive second-order modulation sideband. As a result, carrier-suppressed single-sideband FMCW modulation with doubled bandwidth is achieved. This bandwidth enhancement significantly improves the range resolution of FMCW LiDAR. Experimental results show that the proposed FMCW laser scheme achieves a wide frequency bandwidth of 6 GHz, a residual nonlinearity as low as <inline-formula> <tex-math>$10.3boldsymbol {times } 10{^{text {-5}}}$ </tex-math></inline-formula>, and a fast chirp rate of 2.4 GHz/<inline-formula> <tex-math>$upmu $ </tex-math></inline-formula>s. Additionally, the feasibility of LiDAR ranging based on the proposed FMCW laser scheme was demonstrated. The LiDAR system exhibits a range resolution of 2.5 cm, matching the theoretical value. Notably, the proposed scheme eliminates the need for complex modulators, optical filters, and optical amplifiers, while reducing the required electronic bandwidth, thereby facilitating a significant reduction in system cost.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 7","pages":"443-446"},"PeriodicalIF":2.5,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145861206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A method for distributed polarization mode dispersion (PMD) measurement based on machine learning assisted POTDR is presented in this study, which extracts the characteristics of polarization optical time-domain reflectometer (POTDR) curves and inputs them into a pre-trained machine learning model to obtain distributed PMD values. Compared with traditional distributed PMD measurement methods, this proposed method achieves an average local differential group delay (DGD) measurement accuracy of 0.05 ps/km over 50 m, while improving measurement efficiency by 75% compared to methods with similar accuracy, and significantly enhancing the simplicity and efficiency of distributed PMD measurement. The performance of multiple machine learning models for distributed PMD measurement is compared, providing a basis for selecting models for real-time measurement of distributed PMD in optical fiber composite overhead ground wire (OPGW) under different dynamic environments.
{"title":"Distributed PMD Measurement Based on Machine Learning Assisted POTDR","authors":"Xingrui Su;Kaijing Hu;Wei Li;Ming Luo;Weihua Lian;Chen Qiu;JieKui Yu;Yi Jiang;Ran Yan;Yujia Hu","doi":"10.1109/LPT.2025.3645188","DOIUrl":"https://doi.org/10.1109/LPT.2025.3645188","url":null,"abstract":"A method for distributed polarization mode dispersion (PMD) measurement based on machine learning assisted POTDR is presented in this study, which extracts the characteristics of polarization optical time-domain reflectometer (POTDR) curves and inputs them into a pre-trained machine learning model to obtain distributed PMD values. Compared with traditional distributed PMD measurement methods, this proposed method achieves an average local differential group delay (DGD) measurement accuracy of 0.05 ps/km over 50 m, while improving measurement efficiency by 75% compared to methods with similar accuracy, and significantly enhancing the simplicity and efficiency of distributed PMD measurement. The performance of multiple machine learning models for distributed PMD measurement is compared, providing a basis for selecting models for real-time measurement of distributed PMD in optical fiber composite overhead ground wire (OPGW) under different dynamic environments.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 6","pages":"418-421"},"PeriodicalIF":2.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145830938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1109/LPT.2025.3645230
Yulong Zhao;Shenglin Zeng;Zhijun Sun
Computational spectrometers have strong potentials in miniaturization of spectrometer, and have attracted broad interests. But bottleneck problems still exist in their practical performance, stability, cost and mass production. This work aims on a competitive type of computational spectrometer based on Fabry–Perot (F–P) microcavity array, and proposes methods in facile fabrication of the F–P microcavity array with different thicknesses of cavity media and in–situ characterization of it installed in a spectrometer module to extract preset calibration data for reconstructive measurement of optical spectrum. Fabrication of the F–P microcavity array involves only film deposition and UV photolithography techniques in an elaborately designed multiple–step processing flow. In characterization of the microcavity array, responses of the assembled spectrometer module to monochromatic light at different wavelengths are recorded by an inside image sensor. As–obtained calibration data is supposed to include various system errors and uncertain factors for spectral reconstruction.
{"title":"Fabrication and Characterization of a Fabry–Perot Microcavity Array for Computational Spectrometers","authors":"Yulong Zhao;Shenglin Zeng;Zhijun Sun","doi":"10.1109/LPT.2025.3645230","DOIUrl":"https://doi.org/10.1109/LPT.2025.3645230","url":null,"abstract":"Computational spectrometers have strong potentials in miniaturization of spectrometer, and have attracted broad interests. But bottleneck problems still exist in their practical performance, stability, cost and mass production. This work aims on a competitive type of computational spectrometer based on Fabry–Perot (F–P) microcavity array, and proposes methods in facile fabrication of the F–P microcavity array with different thicknesses of cavity media and in–situ characterization of it installed in a spectrometer module to extract preset calibration data for reconstructive measurement of optical spectrum. Fabrication of the F–P microcavity array involves only film deposition and UV photolithography techniques in an elaborately designed multiple–step processing flow. In characterization of the microcavity array, responses of the assembled spectrometer module to monochromatic light at different wavelengths are recorded by an inside image sensor. As–obtained calibration data is supposed to include various system errors and uncertain factors for spectral reconstruction.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 6","pages":"402-405"},"PeriodicalIF":2.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145808575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1109/LPT.2025.3645227
Feng Xu;Rongqiu Mu;Feixiang Zheng;Zhenyong Dong;Guanghui Wang;Rugang Wang
In this letter, symmetry-broken silicon cuboid tetramer clusters (SSCTC) have been proposed for optical separation of enantiomers, leveraging the enhanced electromagnetic field generated by quasi bound states in the continuum (q-BIC). When the SSCTC is excited at its resonant wavelength with arbitrary polarization, q-BIC will be excited and both the electromagnetic chirality gradient and electromagnetic density will be enhanced. This produces a chiral lateral force on a nanoparticle that is one order of magnitude stronger than non-lateral force, causing the sideways motion of paired enantiomers to exhibit different directions. Our comprehensive simulations demonstrate that the SSCTC will offer high efficiency for chiral particle separation with the consideration of Brownian motion and chiral gradient force. Furthermore, the relationships of separation efficiency and chirality or size of nanoparticles have been investigated. We believe that our research will move forward the techniques of chiral optical tweezers and all-optical enantioseparation in pharmaceutical industries
{"title":"Optical Separation of Enantiomers Using Polarization-Independent Quasi BIC","authors":"Feng Xu;Rongqiu Mu;Feixiang Zheng;Zhenyong Dong;Guanghui Wang;Rugang Wang","doi":"10.1109/LPT.2025.3645227","DOIUrl":"https://doi.org/10.1109/LPT.2025.3645227","url":null,"abstract":"In this letter, symmetry-broken silicon cuboid tetramer clusters (SSCTC) have been proposed for optical separation of enantiomers, leveraging the enhanced electromagnetic field generated by quasi bound states in the continuum (q-BIC). When the SSCTC is excited at its resonant wavelength with arbitrary polarization, q-BIC will be excited and both the electromagnetic chirality gradient and electromagnetic density will be enhanced. This produces a chiral lateral force on a nanoparticle that is one order of magnitude stronger than non-lateral force, causing the sideways motion of paired enantiomers to exhibit different directions. Our comprehensive simulations demonstrate that the SSCTC will offer high efficiency for chiral particle separation with the consideration of Brownian motion and chiral gradient force. Furthermore, the relationships of separation efficiency and chirality or size of nanoparticles have been investigated. We believe that our research will move forward the techniques of chiral optical tweezers and all-optical enantioseparation in pharmaceutical industries","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 7","pages":"439-442"},"PeriodicalIF":2.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145861211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1109/LPT.2025.3645225
Jiaqi Wang;Hongjia Lin;Zhi Luo;Chao Lu;Tianhua Feng;Zhaohui Li
In this letter, we present a strategy for compact mid-wave infrared (MWIR) spectrometers based on all-dielectric metasurfaces to address the limitations in spectral resolution and footprint. All-dielectric metasurfaces with both electric and magnetic dipole-like resonances are employed to generate distinct broadband transmission spectra, thereby promising high accuracy and resolution for spectral reconstruction. Using only nine metasurfaces of silicon nanowires on a calcium fluoride substrate in combination with compressed sensing and dictionary learning algorithms, the proposed spectrometer achieves a spectral resolution of 10 nm across the 3-$5~mu $ m wavelength range, leading to a large spectral channel density of up to 200, surpassing most reported MWIR computational spectrometers. Furthermore, the reconstruction of the absorption spectra of both carbon dioxide and ethane is successfully demonstrated.
{"title":"Computational Mid-Wave Infrared Spectrometers Based on All-Dielectric Metasurfaces With Dipole Resonances","authors":"Jiaqi Wang;Hongjia Lin;Zhi Luo;Chao Lu;Tianhua Feng;Zhaohui Li","doi":"10.1109/LPT.2025.3645225","DOIUrl":"https://doi.org/10.1109/LPT.2025.3645225","url":null,"abstract":"In this letter, we present a strategy for compact mid-wave infrared (MWIR) spectrometers based on all-dielectric metasurfaces to address the limitations in spectral resolution and footprint. All-dielectric metasurfaces with both electric and magnetic dipole-like resonances are employed to generate distinct broadband transmission spectra, thereby promising high accuracy and resolution for spectral reconstruction. Using only nine metasurfaces of silicon nanowires on a calcium fluoride substrate in combination with compressed sensing and dictionary learning algorithms, the proposed spectrometer achieves a spectral resolution of 10 nm across the 3-<inline-formula> <tex-math>$5~mu $ </tex-math></inline-formula>m wavelength range, leading to a large spectral channel density of up to 200, surpassing most reported MWIR computational spectrometers. Furthermore, the reconstruction of the absorption spectra of both carbon dioxide and ethane is successfully demonstrated.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 6","pages":"406-409"},"PeriodicalIF":2.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145830930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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