{"title":"An Ultra-Narrow High-Power Faraday Laser Locked to the D1 Line of Rubidium","authors":"Tianyi Du;Fubin Luo;Zining Yang;Longfei Jiang;Ruiyun Tang;Qingshan Liu;Huizi Zhao;Rui Wang;Hongyan Wang;Xiaojun Xu","doi":"10.1109/LPT.2025.3583700","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583700","url":null,"abstract":"We reported a new kind of 795 nm ultra-narrow external cavity diode lasers (ECDLs). A Faraday anomalous dispersion optical filter (FADOF) was used to construct the external cavity. The spectrum of the diode laser was strictly locked to the D1-line (~794.98 nm), and the bandwidth (FWHM) was narrowed from 2.5 nm in the free-running case to 0.005 nm (2.5 GHz) with a side mode suppression ratio of 26 dB. The final output power of the diode laser was 58 W, with an external cavity efficiency of 60%. The diode laser with such spectrum characteristics and output power could have wide applications, including biomedical magnetic resonance imaging (MRI), free-space optical communications, spin-exchange optical pumping, fundamental spin physics research, etc.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 20","pages":"1161-1164"},"PeriodicalIF":2.3,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144640941","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}
Che-Chung Chou;Cheng-Chieh Hsieh;Ko-Han Chen;Yi-Jun Xu;Wang-Yau Cheng;Tyson Lin;Sheng-Hua Lu
{"title":"Simple Hertz-Level Laser Offset Locking by Using a Dual-Bandwidth Digital Band-Pass Filter","authors":"Che-Chung Chou;Cheng-Chieh Hsieh;Ko-Han Chen;Yi-Jun Xu;Wang-Yau Cheng;Tyson Lin;Sheng-Hua Lu","doi":"10.1109/LPT.2025.3583756","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583756","url":null,"abstract":"This letter presents a simple and easy-to-use self-referenced frequency discriminator for laser frequency offset locking. The key component of the “self-referenced” frequency discriminator is a dual bandwidth band-pass filter which is composed of two digital band-pass filters, one having a broader bandwith to provide a large capture range and the other having a narrow bandwidth for tight frequency locking. The digital band-pass filters are based on the PyRPL IQ modules running on a Red Pitaya STEMlab board. All the parameters of the IQ modules can be easily set and adjusted in the PyRPL GUI. To demonstrate the proposed scheme, we offset locked an external cavity diode laser to an iodine-stabilized external cavity diode laser. Their beat note was narrowed down from 500 kHz of the free running to 4 Hz as offset locked. The minimum Allan deviation of the locked offset frequency is 2.4 Hz at 100-s averaging.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 19","pages":"1113-1116"},"PeriodicalIF":2.3,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557755","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}
{"title":"Hyperspectral Phase Imaging via Optical Differential Microscopy","authors":"Ling Ye;An Wang;Xiong Liu;Yurong Liu;Su Li;Lan Luo;Rongchun Ge;Zhiyou Zhang","doi":"10.1109/LPT.2025.3583464","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583464","url":null,"abstract":"Edge detection is critical for emerging image processing technologies. Here, we present a dual-channel optical differential system that faithfully retrieves full edges of two-dimensional (2D) images. The system, leveraging the modified Wollaston prism, is compatible with hyperspectral imaging (HSI), enabling real-time phase imaging across 450-750 nm with 30 spectral channels. Experimental results demonstrate that the peak signal-to-noise ratio (PSNR) of the image is improved over 6 dB with the proposed system. Meanwhile, it indicates that edge imaging can achieve higher contrast on biological samples. This work demonstrates the system’s potential for wide applications like target recognition and image enhancement, laying the foundation for hyperspectral phase edge microscopy.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 19","pages":"1085-1088"},"PeriodicalIF":2.3,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144556573","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}
{"title":"High-Precision Optical Transfer Delay Measurement Using Optical-Comb-Assisted Phase-Derived Ranging","authors":"Xingyu Liu;Xiaolong Zhao;Bin Wang;Weifeng Zhang","doi":"10.1109/LPT.2025.3583484","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583484","url":null,"abstract":"We propose and experimentally demonstrate an approach for high-precision optical transfer delay measurement based on phase-derived ranging powered by a frequency-agile electro-optic comb. When the optical comb passes through a Mach-Zehnder interferometer, a reference frequency-shifted comb and a probe comb carrying distance information of targets are created. After filtering and heterodyne detection, two electrical signals are generated and sent to a narrowband phase detector for phase extraction, from which distance information or transfer delay can be recovered. Thanks to the broad comb spectrum, high-order comb lines exhibit high sensitivity to propagation distance and transfer the phase to the generated low-frequency electrical signals, significantly enhancing measurement precision. Experimental demonstrations show that a precision of ±10.5 fs is achieved, with a measurement range up to 50 km. Furthermore, a free-space distance measurement is performed, and a precision as small as <inline-formula> <tex-math>$2.8~mu $ </tex-math></inline-formula>m is realized. The proposed system holds great potential for widespread use in distributed network systems and 3D imaging systems.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 19","pages":"1093-1096"},"PeriodicalIF":2.3,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557947","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}
{"title":"Enhancing Excitation Efficiency of Spoof Surface Plasmons in Backward-Wave Regime","authors":"Yong-Qiang Liu;Jinhai Sun;Wei Dai;Chao-Hai Du","doi":"10.1109/LPT.2025.3583489","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583489","url":null,"abstract":"Spoof surface plasmons (SSPs) on the periodic structures have aroused great attentions due to its extraordinary properties and novel applications. Up to now, the studies are limited to forward SSPs mode and the backward-wave SSPs (BWSSPs) have received little attentions in the community. In this letter, a new excitation method of BWSSPs on the uniform metal grating by using electron beam is proposed and validated by numerical simulations in Terahertz (THz) band. Due to its distinct dispersion characteristic in the first negative spatial harmonic wave region (<inline-formula> <tex-math>$n=-1$ </tex-math></inline-formula>), the propagation direction of generated BWSSPs is inverse to the electron beam. Besides, the matched momentum of BWSSPs which couples to free electron beam is larger than that of forward SSPs, thus leads to the required electron beam voltage significantly decreases. As a result, the excitation efficiency of BWSSPs by low-voltage electron beam is enhanced by double times compared to forward mode excitation according to the SSPs power spectrums. This work can provide a simple yet high-efficiency excitation method of SSPs mode working at backward regime. Moreover, it can open up new ways for the development of novel BWSSPs-based devices (e. g., sensors, couplers and radiation sources, etc.) in THz and/or microwave band.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 19","pages":"1089-1092"},"PeriodicalIF":2.3,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144556575","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}
{"title":"Generation of 435 MHz, Ultrafast Cylindrical Vector Pulses From a Mode-Locked Fiber Laser","authors":"Chixuan Zou;Zichen Zhao;Mengyun Hu;Guangyi Wu;Junyu Chen;Yanshu Wu;Tao Liu;Shuai Yuan","doi":"10.1109/LPT.2025.3583586","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583586","url":null,"abstract":"Cylindrical vector beams have spawned numerous applications in modern optics. Although cylindrical vector pulses with several tens of megahertz repetition rate can be obtained directly at the laser source with high-purity structured modes, cylindrical vector pulses with hundreds of megahertz or gigahertz repetition rate have greater application prospects in the fields of laser processing and super-resolution imaging. Here, we report on the generation of a repetition-rate of 435.8 MHz, cylindrical vector pulses from a fundamentally mode-locked Yb-doped solid-state fiber laser. The nonlinear-polarization-evolution (NPE) mode-locking and high pump power injection enabled short pulses with high repetition rate, while on-demanded cylindrical vector beams including radially and azimuthally polarized beams were yielded by adjusting the polarization control elements inside the cavity. Mode-locked pulses were delivered with an average power of 315 mW, a spectrum bandwidth of 23 nm, and a pulse duration of 904 fs. To the best of our knowledge, it is the highest repetition rate from a fundamentally mode-locked Yb-fiber laser which directly generates cylindrical vector pulses.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 20","pages":"1145-1148"},"PeriodicalIF":2.3,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597656","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}
Yixian Dong;Qing Zhang;Yiqian Shi;Wentao Lv;Xihua Zou;Wei Pan;Lianshan Yan
{"title":"Enhanced Reservoir Computing With Simplified Feedback for IMDD Transmission Equalization","authors":"Yixian Dong;Qing Zhang;Yiqian Shi;Wentao Lv;Xihua Zou;Wei Pan;Lianshan Yan","doi":"10.1109/LPT.2025.3583440","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583440","url":null,"abstract":"By eliminating redundant feedback mechanisms, we propose and experimentally validate an enhanced reservoir computing (RC)-based equalizer with simplified feedback for intensity modulation direct detection (IMDD) short-reach optical transmission systems. Experimental results demonstrate that the simplified model, which retains only the reservoir feedback loop and reduces the number of trainable parameters, achieves bit error rate (BER) performance comparable to the dual-feedback model. Without compromising equalization effectiveness, the proposed architecture reduces computational complexity and enhance scalability for practical deployment in high-speed optical networks.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 19","pages":"1137-1140"},"PeriodicalIF":2.3,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597918","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}
{"title":"SnS2 and SnS Heterostructure Based High Responsivity Broadband Photodetector","authors":"Akshay Yadav;Tulika Bajpai;Satyabrata Jit;Shweta Tripathi","doi":"10.1109/LPT.2025.3583064","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583064","url":null,"abstract":"This study reports the fabrication, and performance evaluation of an innovative Al/PEDOT: PSS/SnS/SnS2/FTO/Glass photodetector. Utilizing a layered architecture, the device incorporates Al as an electrode, PEDOT: PSS as a hole transport layer (HTL), SnS and SnS2 as the active layer, fabricated on FTO coated glass substrate. The photodetector demonstrates high external quantum efficiency across a broad spectral range of UV, visible and near-infrared (NIR) regions. The proposed device displays a high External Quantum Efficiency EQE (%)/Responsivity Rs(A/W) of <inline-formula> <tex-math>$1.98 times 10~^{4}$ </tex-math></inline-formula>%/56.14, <inline-formula> <tex-math>$7.61 times 10~^{4}$ </tex-math></inline-formula>%/307.15, <inline-formula> <tex-math>$7.74 times 10~^{3}$ </tex-math></inline-formula>% / 71.70 at 350 nm (UV), 500 nm (Visible) and 1150 nm (NIR) respectively, at −1Vbias.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 20","pages":"1149-1152"},"PeriodicalIF":2.3,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597782","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}
Yan Song;Zhezheng Wang;Bingrui Sun;Bo Peng;Tiantao Hu;Zhiyao Zhang;Bao Sun;Yong Liu
{"title":"A Compact and Temperature-Insensitive Optical Electric Field Sensor Based on Thin-Film Lithium Niobate Waveguides","authors":"Yan Song;Zhezheng Wang;Bingrui Sun;Bo Peng;Tiantao Hu;Zhiyao Zhang;Bao Sun;Yong Liu","doi":"10.1109/LPT.2025.3583002","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583002","url":null,"abstract":"We propose a temperature-insensitive sensor using a compact X-cut thin-film lithium niobate (TFLN) Mach-Zehnder interferometer with quasi-symmetric arms (<inline-formula> <tex-math>$700times 900~mu $ </tex-math></inline-formula>m) and non-obstructive electrodes, suppressing thermal imbalance between waveguide arms. By optimizing the optical path difference and leveraging the low thermal expansion coefficient of silicon substrate, the sensor achieves intrinsic thermal stability without active tuning. Experimental results demonstrate 0.2 rad bias stability across <inline-formula> <tex-math>$0~^{circ } $ </tex-math></inline-formula>C to <inline-formula> <tex-math>$70~^{circ } $ </tex-math></inline-formula>C with <2 dB RF response error for fields spanning 250 MHz–3 GHz and 0 dBV/m–45 dBV/m.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 20","pages":"1153-1156"},"PeriodicalIF":2.3,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597874","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}
{"title":"Beam Shaping of VCSEL Arrays Utilizing Liquid Crystal Spatial Light Modulation","authors":"Dong Sun;Hesen Dai;Hongyi Lin;Wei Qiao;Zichen Zhang;Shufan Li;Jianjian Ruan","doi":"10.1109/LPT.2025.3583264","DOIUrl":"https://doi.org/10.1109/LPT.2025.3583264","url":null,"abstract":"Beam shaping and uniformity are critical requirements in various optical applications, including laser processing, aesthetic treatments, medical therapies, holography, and optical communication. The Gerchberg-Saxton (GS) algorithm and the hybrid input-output (HIO) algorithm are widely used for beam shaping; however, they exhibit notable limitations. While the GS algorithm converges quickly, it is prone to stagnation at local minima. Conversely, the HIO algorithm improves exploration but suffers from instability due to fixed parameter settings. This study proposes an improved phase retrieval algorithm that integrates the strengths of both GS and HIO. It introduces an adaptive damping factor (<inline-formula> <tex-math>$alpha $ </tex-math></inline-formula>) that increases over iterations to enhance uniformity while maintaining stability. Additionally, a dynamic interpolation strategy is applied to the <inline-formula> <tex-math>$beta $ </tex-math></inline-formula> parameter to prevent divergence. Numerical simulations confirm the superior performance of the proposed method, achieving a beam uniformity of 88.62% and an energy efficiency of 72.63%, outperforming both the GS and HIO algorithms. This method effectively balances convergence speed, stability, and uniformity, offering a promising solution for high-precision beam shaping. In the experimental validation, the generated grayscale hologram is uploaded to the liquid crystal spatial light modulator (LCSLM), thereby facilitating the homogenization of the vertical-cavity surface-emitting laser (VCSEL) beam. This process yields a rectangular flat-top beam with a measured beam uniformity of 83.85%.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"37 19","pages":"1097-1100"},"PeriodicalIF":2.3,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144556574","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}