Pub Date : 2026-07-01Epub Date: 2026-02-12DOI: 10.1016/j.yofte.2026.104589
Andrei A. Stolov, Michael J. Joyce, Matthew Popelka, Ping Lu
Specialty hydrophilic, UV-curable acrylate coatings were engineered to enable distributed humidity sensing through optical fibers. Fibers with such coatings were utilized for relative humidity (RH) sensing using Optical Frequency Domain Reflectometry (OFDR) and Brillouin Optical Time-Domain Analysis (BOTDA). At room temperature, these fibers demonstrated a 5–7 times higher sensitivity to RH in comparison with conventional polyimide-coated fibers. The sensitivity can be further enhanced by applying additional coating layers, which is doable via conventional UV-cure coating method. With the newly designed coatings, the RH-sensitivity was found to decrease with the temperature due to the coating softening effect. A novel method was introduced for simultaneous distributed measurement of humidity and temperature, employing a dual-fiber approach: one fiber with enhanced RH sensitivity and another with standard sensitivity. The proposed approach accounts for the modulus variations of the coating materials as functions of both humidity and temperature, enabling accurate decoupling of the two parameters.
{"title":"Distributed humidity sensing via optical fibers with specialty acrylate coatings","authors":"Andrei A. Stolov, Michael J. Joyce, Matthew Popelka, Ping Lu","doi":"10.1016/j.yofte.2026.104589","DOIUrl":"10.1016/j.yofte.2026.104589","url":null,"abstract":"<div><div>Specialty hydrophilic, UV-curable acrylate coatings were engineered to enable distributed humidity sensing through optical fibers. Fibers with such coatings were utilized for relative humidity (RH) sensing using Optical Frequency Domain Reflectometry (OFDR) and Brillouin Optical Time-Domain Analysis (BOTDA). At room temperature, these fibers demonstrated a 5–7 times higher sensitivity to RH in comparison with conventional polyimide-coated fibers. The sensitivity can be further enhanced by applying additional coating layers, which is doable via conventional UV-cure coating method. With the newly designed coatings, the RH-sensitivity was found to decrease with the temperature due to the coating softening effect. A novel method was introduced for simultaneous distributed measurement of humidity and temperature, employing a dual-fiber approach: one fiber with enhanced RH sensitivity and another with standard sensitivity. The proposed approach accounts for the modulus variations of the coating materials as functions of both humidity and temperature, enabling accurate decoupling of the two parameters.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"99 ","pages":"Article 104589"},"PeriodicalIF":2.7,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-11DOI: 10.1016/j.yofte.2026.104580
Abdulwahhab Essa Hamzah , Nurfarhana Mohamad Sapiee , Mustafa Essa Hamzah , Mahmoud Muhanad Fadhel , Aqilah Baseri Huddin , Mahmood A. Al-Shareeda , Hisham Mohamad , Abdulfatah A.G. Abushagur , Norhana Arsad , Sawal Hamid Md Ali , Mohd Saiful Dzulkefly Zan , Ahmad Ashrif A Bakar
<div><div>Significant advancements have been made in distributed Brillouin optical time-domain analysis (BOTDA) fiber sensing, with a particular focus on rapid measurement techniques. This review comprehensively discusses the latest methods for measuring temperature and strain in dynamic environments subject to vibrations and pressure. We first examine the fundamental principles of BOTDA fiber sensors and evaluate the speed limitations of conventional systems. The paper then analyzes and summarizes modern hardware and software solutions that address the time-consuming nature of traditional frequency scanning. Specifically, we detail advancements in fast frequency scanning, signal detection, and data processing, including the application of machine learning algorithms. The paper also discusses the current challenges and future directions for high-speed BOTDA technology, which are critical for developing more powerful, flexible, and efficient applications. Ultimately, this review serves as a valuable resource for researchers aiming to improve rapid measurement techniques in distributed Brillouin optical time-domain analysis fiber sensors.</div><div>Abbreviations: AI, Artificial Intelligence; ANN, Artificial Neural Network; AWG, Arbitrary Waveform Generator; BFS, Brillouin Frequency Shift; BGS, Brillouin Gain Spectrum; BOCDA, Brillouin Optical Correlation-Domain Analysis; BOCDR, Brillouin Optical Correlation-Domain Reflectometry; BOTDA, Brillouin Optical Time-Domain Analysis; BOTDR, Brillouin Optical Time-Domain Reflectometry; BP, Back Propagation; BPS, Brillouin Phase Spectrum; CAZAC, Constant Amplitude Zero Auto Correlation; CNN, Convolutional Neural Network; CPCA, Complex Principal Component Analysis; CW, Continuous Wave; DAE, Denoising Autoencoder; DAQ, Data Acquisition; DBOFS, Distributed Brillouin Optical Fiber Sensors; DL, Deep Learning; DNN, Deep Neural Network; DOFS, Distributed Optical Fiber Sensors; DPP, Differential Pulse-Pair; DSS, Distributed Strain Sensing; DTS, Distributed Temperature Sensing; DTSS, Distributed Temperature and Strain Sensing; ELM, Extreme Learning Machine; EOM, Electro-Optic Modulator; ESN, Echo State Network; F-BOTDA, Fast BOTDA; FNN, Feedforward Neural Network; FUT, Fiber Under Test; GAN, Generative Adversarial Network; GLM, Generalized Linear Model; IM-DD, Intensity Modulation-Direct Detection; IQ, In-Phase Quadrature; K-ELM, Kernel Extreme Learning Machine; K-SVD, K-Singular Value Decomposition; KNN, K-Nearest Neighbour; LCF, Lorentz Curve Fitting; LEAF, Large Effective Area Fiber; LSTM, Long Short-Term Memory; MAE, Mean Absolute Error; ML, Machine Learning; OCC, Optical Chirp Chain; OFA, Optical Frequency-Agile; OFC, Optical Frequency Comb; OFDM, Orthogonal Frequency Division Multiplexing; PAPR, Peak-to-Average Power Ratio; PC, Polarization Controller; PCA, Principal Component Analysis; K-ELM, Kernel Extreme Learning Machine; K-SVD, K-Singular Value Decomposition; KNN, K-Nearest Neighbour; LCF, Lorentz Curve Fit
分布式布里渊光时域分析（BOTDA）光纤传感技术取得了重大进展，特别是在快速测量技术方面。本文全面讨论了在振动和压力的动态环境中测量温度和应变的最新方法。我们首先研究了BOTDA光纤传感器的基本原理，并评估了传统系统的速度限制。然后分析和总结了现代硬件和软件解决方案，解决了传统频率扫描耗时的本质。具体来说，我们详细介绍了快速频率扫描、信号检测和数据处理方面的进展，包括机器学习算法的应用。本文还讨论了高速BOTDA技术的当前挑战和未来方向，这对于开发更强大、更灵活和更高效的应用至关重要。最后，本综述为旨在改进分布式布里渊光时域分析光纤传感器快速测量技术的研究人员提供了宝贵的资源。缩写：AI，人工智能；人工神经网络；AWG，任意波形发生器；布里渊频移；布里渊增益谱；布里渊光相关域分析；布里渊光相关域反射法；布里渊光时域分析；布里渊光时域反射法；BP，反向传播；布里渊相谱；等幅零自相关；CNN，卷积神经网络；复合主成分分析；连续波；DAE，去噪自动编码器；DAQ，数据采集；分布式布里渊光纤传感器；深度学习；深度神经网络；分布式光纤传感器；差分脉冲对；分布式应变传感；DTS，分布式温度传感；DTSS，分布式温度应变传感；极限学习机；电光调制器；回声状态网络；F-BOTDA, Fast BOTDA；前馈神经网络；FUT，待测纤维；GAN，生成对抗网络；广义线性模型；强度调制-直接检测；IQ，同相正交；核极限学习机；K-SVD， k奇异值分解；KNN， k -近邻；洛伦兹曲线拟合；LEAF：大有效面积纤维；LSTM，长短期记忆；平均绝对误差；ML，机器学习；OCC，光啁啾链；OFA，光频率捷变；OFC，光频梳；正交频分复用；峰值-平均功率比；PC，偏振控制器；主成分分析；核极限学习机；K-SVD， k奇异值分解；KNN， k -近邻；洛伦兹曲线拟合；LEAF：大有效面积纤维；LSTM，长短期记忆；平均绝对误差；ML，机器学习；OCC，光啁啾链；OFA，光频率捷变；OFC，光频梳；正交频分复用；峰值-平均功率比；PC，偏振控制器；主成分分析；PCA-PDNN， pca训练概率深度神经；、网络;PD,光电探测器;PID, Proportional-Integral-Derivative;PT, Peak-Tracking;强化学习；RNN，递归神经网络；SA, Slope-Assisted;SA-BOTDA，斜坡辅助BOTDA；受激布里渊散射；自去噪网络；单模光纤；信噪比；信噪比；SS-BOTDA，斜率BOTDA；支持向量机；支持向量回归。
{"title":"Advancement in fast measurement and processing techniques of distributed Brillouin optical time-domain analysis fiber sensors: Methods, challenges, and future directions","authors":"Abdulwahhab Essa Hamzah , Nurfarhana Mohamad Sapiee , Mustafa Essa Hamzah , Mahmoud Muhanad Fadhel , Aqilah Baseri Huddin , Mahmood A. Al-Shareeda , Hisham Mohamad , Abdulfatah A.G. Abushagur , Norhana Arsad , Sawal Hamid Md Ali , Mohd Saiful Dzulkefly Zan , Ahmad Ashrif A Bakar","doi":"10.1016/j.yofte.2026.104580","DOIUrl":"10.1016/j.yofte.2026.104580","url":null,"abstract":"<div><div>Significant advancements have been made in distributed Brillouin optical time-domain analysis (BOTDA) fiber sensing, with a particular focus on rapid measurement techniques. This review comprehensively discusses the latest methods for measuring temperature and strain in dynamic environments subject to vibrations and pressure. We first examine the fundamental principles of BOTDA fiber sensors and evaluate the speed limitations of conventional systems. The paper then analyzes and summarizes modern hardware and software solutions that address the time-consuming nature of traditional frequency scanning. Specifically, we detail advancements in fast frequency scanning, signal detection, and data processing, including the application of machine learning algorithms. The paper also discusses the current challenges and future directions for high-speed BOTDA technology, which are critical for developing more powerful, flexible, and efficient applications. Ultimately, this review serves as a valuable resource for researchers aiming to improve rapid measurement techniques in distributed Brillouin optical time-domain analysis fiber sensors.</div><div>Abbreviations: AI, Artificial Intelligence; ANN, Artificial Neural Network; AWG, Arbitrary Waveform Generator; BFS, Brillouin Frequency Shift; BGS, Brillouin Gain Spectrum; BOCDA, Brillouin Optical Correlation-Domain Analysis; BOCDR, Brillouin Optical Correlation-Domain Reflectometry; BOTDA, Brillouin Optical Time-Domain Analysis; BOTDR, Brillouin Optical Time-Domain Reflectometry; BP, Back Propagation; BPS, Brillouin Phase Spectrum; CAZAC, Constant Amplitude Zero Auto Correlation; CNN, Convolutional Neural Network; CPCA, Complex Principal Component Analysis; CW, Continuous Wave; DAE, Denoising Autoencoder; DAQ, Data Acquisition; DBOFS, Distributed Brillouin Optical Fiber Sensors; DL, Deep Learning; DNN, Deep Neural Network; DOFS, Distributed Optical Fiber Sensors; DPP, Differential Pulse-Pair; DSS, Distributed Strain Sensing; DTS, Distributed Temperature Sensing; DTSS, Distributed Temperature and Strain Sensing; ELM, Extreme Learning Machine; EOM, Electro-Optic Modulator; ESN, Echo State Network; F-BOTDA, Fast BOTDA; FNN, Feedforward Neural Network; FUT, Fiber Under Test; GAN, Generative Adversarial Network; GLM, Generalized Linear Model; IM-DD, Intensity Modulation-Direct Detection; IQ, In-Phase Quadrature; K-ELM, Kernel Extreme Learning Machine; K-SVD, K-Singular Value Decomposition; KNN, K-Nearest Neighbour; LCF, Lorentz Curve Fitting; LEAF, Large Effective Area Fiber; LSTM, Long Short-Term Memory; MAE, Mean Absolute Error; ML, Machine Learning; OCC, Optical Chirp Chain; OFA, Optical Frequency-Agile; OFC, Optical Frequency Comb; OFDM, Orthogonal Frequency Division Multiplexing; PAPR, Peak-to-Average Power Ratio; PC, Polarization Controller; PCA, Principal Component Analysis; K-ELM, Kernel Extreme Learning Machine; K-SVD, K-Singular Value Decomposition; KNN, K-Nearest Neighbour; LCF, Lorentz Curve Fit","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"99 ","pages":"Article 104580"},"PeriodicalIF":2.7,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, we have studied an exotic incomplete mode locking regime featuring intermittent pulse emission, generated in a thulium-doped fiber laser (TDFL) emitting at 1900 nm, where the deliberate omission of a polarizer plays a crucial role. The emission of this figure-eight laser (F8L) scheme, which includes a peculiar polarization-sensitive NOLM architecture, is formed in one phase by clusters of light with quite irregular but well-delimited temporal profiles, which we have entitled islands; in another phase, it also includes a quasi-continuous mode-locked emission, which we have called the main bunch. While the islands are structures lasting about 100 cycles each (and which are either completely isolated or grouped adjoined into a small number of them), the main bunch is a structure that is maintained for thousands of cycles, undergoing some quasi-periodic fluctuations in its temporal profile that vanish near the middle of its lifespan. The dynamics is further complicated by a significant shifting toward shorter times affecting particularly isolated islands. On the other hand, several islands may appear tightly bound together (adjoined islands). The dynamics change when these structures get very tightly connected and repeat quasi-periodically giving rise to the main bunch, going from irregular oscillations dominated by polarization dynamics to quasi-periodic emissions related to gain dynamics. Although the latter initially presents an adjoined-islands-like profile, with marked and sharp edges over a few hundred cycles, the edges blur and the distinction between individual island structures vanish, giving way to a nearly uniform light flux. A few hundred cycles before its extinction, the pattern of adjoined islands reappears, until the bunch dramatically vanishes in the background radiation. Another particularity of the main bunch is that it continually releases fragments towards shorter times, which either disappear without a trace during the bunch lifetime or promote the formation of islands beyond the main bunch extinction. We believe that this study can contribute to a better understanding of irregular dynamics, as well as the emergence of more stable regimes in these complex systems, which would be useful for industrial or medical applications.
{"title":"Intermittent irregular, quasi-periodic and quasi-stationary pulse emission in a thulium-doped fiber laser without polarization control","authors":"J.P. Lauterio-Cruz , O. Pottiez , H.E. Ibarra-Villalon , L.A. Rodriguez-Morales , Y.E. Bracamontes-Rodriguez , L.M. Gonzalez-Vidal , J.D. Filoteo-Razo , J.R. Martinez-Angulo , J.C. Hernandez-Garcia","doi":"10.1016/j.yofte.2026.104567","DOIUrl":"10.1016/j.yofte.2026.104567","url":null,"abstract":"<div><div>In this work, we have studied an exotic incomplete mode locking regime featuring intermittent pulse emission, generated in a thulium-doped fiber laser (TDFL) emitting at 1900 nm, where the deliberate omission of a polarizer plays a crucial role. The emission of this figure-eight laser (F8L) scheme, which includes a peculiar polarization-sensitive NOLM architecture, is formed in one phase by clusters of light with quite irregular but well-delimited temporal profiles, which we have entitled islands; in another phase, it also includes a quasi-continuous mode-locked emission, which we have called the main bunch. While the islands are structures lasting about 100 cycles each (and which are either completely isolated or grouped adjoined into a small number of them), the main bunch is a structure that is maintained for thousands of cycles, undergoing some quasi-periodic fluctuations in its temporal profile that vanish near the middle of its lifespan. The dynamics is further complicated by a significant shifting toward shorter times affecting particularly isolated islands. On the other hand, several islands may appear tightly bound together (adjoined islands). The dynamics change when these structures get very tightly connected and repeat quasi-periodically giving rise to the main bunch, going from irregular oscillations dominated by polarization dynamics to quasi-periodic emissions related to gain dynamics. Although the latter initially presents an adjoined-islands-like profile, with marked and sharp edges over a few hundred cycles, the edges blur and the distinction between individual island structures vanish, giving way to a nearly uniform light flux. A few hundred cycles before its extinction, the pattern of adjoined islands reappears, until the bunch dramatically vanishes in the background radiation. Another particularity of the main bunch is that it continually releases fragments towards shorter times, which either disappear without a trace during the bunch lifetime or promote the formation of islands beyond the main bunch extinction. We believe that this study can contribute to a better understanding of irregular dynamics, as well as the emergence of more stable regimes in these complex systems, which would be useful for industrial or medical applications.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"99 ","pages":"Article 104567"},"PeriodicalIF":2.7,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-01-27DOI: 10.1016/j.yofte.2026.104568
Ronghui Xu , Qirui Fang , Yudi Huang , Junhui Hu
We have proposed and experimentally demonstrated a multiwavelength Brillouin-erbium fiber laser (MBEFL) with three output ports and double-Brillouin-frequency spacing. By using a four-port optical circulator(CIR) and three coils of single-mode fiber (SMF), the three-port output MBEFL has been achieved. The three coils of SMF are used to form three laser cavities through three 3 dB fiber optic couplers (OC1/OC2/OC3), and function as the Brillouin gain medium. Three EDFA modules are set in three laser cavities to provide bidirectional optical amplification. In order to optimize the configuration, we systematically investigated the effects of the three cavity lengths, 980 nm pump powers of the three EDFA modules inside the cavity, and Brillouin pump (BP) power on the MBEFL output. The research results indicate that a 10 km long SMF is a more optimized laser cavity length, and the powers of the BP, 980 nm pump powers of the three EDFA have a significant impact on the number and stability of the MBEFL outputs. When 15 mW of BP, 455 mW of Pump1, 450 mW of Pump2 and 36 mW of Pump3 are used, the three output ports produce excellent quality multi-wavelength Brillouin Stokes. In the experiment, twelve even Stokes, eleven odd Stokes and nine even Stokes are simultaneously observed in three output ports, and the average optical signal-to-noise ratio (OSNR) for all three output ports is approximately 24 dB. The wavelength tuning of the MBEFL can be achieved by changing the wavelength of BP light, and the wavelength tuning ranges at all three output ports exceed 15 nm under the optimized configuration, the range at the first output port exceeding 31 nm. This stable and broadly tunable MBEFL holds significant potential for applications in dense wavelength division multiplexing (DWDM) optical communication, optical fiber sensors, and related fields.
{"title":"Double-frequency-spaced multiwavelength Brillouin-erbium fiber laser with three output ports","authors":"Ronghui Xu , Qirui Fang , Yudi Huang , Junhui Hu","doi":"10.1016/j.yofte.2026.104568","DOIUrl":"10.1016/j.yofte.2026.104568","url":null,"abstract":"<div><div>We have proposed and experimentally demonstrated a multiwavelength Brillouin-erbium fiber laser (MBEFL) with three output ports and double-Brillouin-frequency spacing. By using a four-port optical circulator(CIR) and three coils of single-mode fiber (SMF), the three-port output MBEFL has been achieved. The three coils of SMF are used to form three laser cavities through three 3 dB fiber optic couplers (OC1/OC2/OC3), and function as the Brillouin gain medium. Three EDFA modules are set in three laser cavities to provide bidirectional optical amplification. In order to optimize the configuration, we systematically investigated the effects of the three cavity lengths, 980 nm pump powers of the three EDFA modules inside the cavity, and Brillouin pump (BP) power on the MBEFL output. The research results indicate that a 10 km long SMF is a more optimized laser cavity length, and the powers of the BP, 980 nm pump powers of the three EDFA have a significant impact on the number and stability of the MBEFL outputs. When 15 mW of BP, 455 mW of Pump1, 450 mW of Pump2 and 36 mW of Pump3 are used, the three output ports produce excellent quality multi-wavelength Brillouin Stokes. In the experiment, twelve even Stokes, eleven odd Stokes and nine even Stokes are simultaneously observed in three output ports, and the average optical signal-to-noise ratio (OSNR) for all three output ports is approximately 24 dB. The wavelength tuning of the MBEFL can be achieved by changing the wavelength of BP light, and the wavelength tuning ranges at all three output ports exceed 15 nm under the optimized configuration, the range at the first output port exceeding 31 nm. This stable and broadly tunable MBEFL holds significant potential for applications in dense wavelength division multiplexing (DWDM) optical communication, optical fiber sensors, and related fields.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"99 ","pages":"Article 104568"},"PeriodicalIF":2.7,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146049067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-03DOI: 10.1016/j.yofte.2026.104569
Yujia Yin , Suhua Wang , Hongliang Ren , Juanjuan Li , Mingyi Gao
Time-delayed reservoir computing has emerged as an energy-efficient neuromorphic paradigm due to its minimal physical footprint, yet its reliance on feedback-loop-induced fading memory fundamentally limits scalability and task adaptability. In this work, a novel photonic feedforward architecture that eliminates feedback mechanisms while enabling memory-tunable operation is proposed. By exploiting the intrinsic nonlinear response and the light dispersion characteristic of highly nonlinear fiber (HNLF), the system achieves baseline memory properties suitable for simple temporal tasks. For enhanced memory-intensive processing, a dynamic input encoding scheme that systematically modulates temporal correlations without physical structural modifications is utilized. The passive low-loss HNLF implementation ensures ultralow power consumption and broad operational bandwidth, overcoming the bandwidth constraints of active feedback components. The feasibility and effectiveness of the proposed architecture are experimentally validated on two benchmark tasks with distinct memory requirements, the Santa Fe chaotic time series prediction and the NARMA10 prediction. Competitive performance is achieved, with normalized mean square errors of 0.0049 and 0.2159 for the Santa Fe and NARMA10 tasks, respectively.
{"title":"HNLF-based feedforward photonic reservoir computing with adaptive memory","authors":"Yujia Yin , Suhua Wang , Hongliang Ren , Juanjuan Li , Mingyi Gao","doi":"10.1016/j.yofte.2026.104569","DOIUrl":"10.1016/j.yofte.2026.104569","url":null,"abstract":"<div><div>Time-delayed reservoir computing has emerged as an energy-efficient neuromorphic paradigm due to its minimal physical footprint, yet its reliance on feedback-loop-induced fading memory fundamentally limits scalability and task adaptability. In this work, a novel photonic feedforward architecture that eliminates feedback mechanisms while enabling memory-tunable operation is proposed. By exploiting the intrinsic nonlinear response and the light dispersion characteristic of highly nonlinear fiber (HNLF), the system achieves baseline memory properties suitable for simple temporal tasks. For enhanced memory-intensive processing, a dynamic input encoding scheme that systematically modulates temporal correlations without physical structural modifications is utilized. The passive low-loss HNLF implementation ensures ultralow power consumption and broad operational bandwidth, overcoming the bandwidth constraints of active feedback components. The feasibility and effectiveness of the proposed architecture are experimentally validated on two benchmark tasks with distinct memory requirements, the Santa Fe chaotic time series prediction and the NARMA10 prediction. Competitive performance is achieved, with normalized mean square errors of 0.0049 and 0.2159 for the Santa Fe and NARMA10 tasks, respectively.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"99 ","pages":"Article 104569"},"PeriodicalIF":2.7,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-03DOI: 10.1016/j.yofte.2026.104553
Haoyu Jing , Guoying Feng , Jinghua Han
A dual-layer, elliptical, nested-capsule structure was proposed for hollow-core antiresonant fibers (DENC-ARFs). The key parameters of the newly designed fiber structure were optimized through numerical analysis, and finite-element method simulations were used to evaluate the confinement loss, bending loss, and single-mode performance of the design. The simulation results demonstrated that the confinement loss of the proposed structure remained below 0.01 dB/km over a broad wavelength range from 1.1 to 1.65 μm. This value was nearly an order of magnitude lower than that of most nested anti-resonant five-node fibers. Notably, over the 200 nm wavelength range from 1.4 to 1.6 μm, the confinement loss of the proposed structure fell below 0.001 dB/km, however within in the narrower range of 1.5–1.6 μm, the confinement loss exceeded 0.001 dB/km, reaching a minimum of 1.5549 × 10−7 dB/m at 1.5 μm. Furthermore, the bending loss was 5.79 × 10−4 dB/m at a bending radius of 6 cm, reflecting excellent bending performance. The higher-order mode extinction ratio exceeded 10 dB over the wavelength range of 1.3–1.6 μm, meeting the fundamental requirements for communication systems. These results underscore the potential of the proposed structure for applications in optical communication and gas sensing.
{"title":"Low confinement loss anti-resonant hollow-core fiber with a nested capsule shape tube","authors":"Haoyu Jing , Guoying Feng , Jinghua Han","doi":"10.1016/j.yofte.2026.104553","DOIUrl":"10.1016/j.yofte.2026.104553","url":null,"abstract":"<div><div>A dual-layer, elliptical, nested-capsule structure was proposed for hollow-core antiresonant fibers (DENC-ARFs). The key parameters of the newly designed fiber structure were optimized through numerical analysis, and finite-element method simulations were used to evaluate the confinement loss, bending loss, and single-mode performance of the design. The simulation results demonstrated that the confinement loss of the proposed structure remained below 0.01 dB/km over a broad wavelength range from 1.1 to 1.65 μm. This value was nearly an order of magnitude lower than that of most nested anti-resonant five-node fibers. Notably, over the 200 nm wavelength range from 1.4 to 1.6 μm, the confinement loss of the proposed structure fell below 0.001 dB/km, however within in the narrower range of 1.5–1.6 μm, the confinement loss exceeded 0.001 dB/km, reaching a minimum of 1.5549 × 10<sup>−7</sup> dB/m at 1.5 μm. Furthermore, the bending loss was 5.79 × 10<sup>−4</sup> dB/m at a bending radius of 6 cm, reflecting excellent bending performance. The higher-order mode extinction ratio exceeded 10 dB over the wavelength range of 1.3–1.6 μm, meeting the fundamental requirements for communication systems. These results underscore the potential of the proposed structure for applications in optical communication and gas sensing.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"99 ","pages":"Article 104553"},"PeriodicalIF":2.7,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-02-13DOI: 10.1016/j.yofte.2026.104583
Ziyi Fu , Qi Xiao , Ruiqi Wang , Tianye Huang , Hongbo Zheng , Mingqi Fan , Jianxing Pan , Zhuo Cheng , Jing Zhang , Zhichao Wu , Xiang Li , Perry Ping Shum
Ultrafast lasers can generate high-repetition-rate ultrashort pulses through various mode-locking mechanisms. However, research on generating high-repetition-rate pulses based on nonlinear multimode interference is still relatively limited. In this paper, we propose and demonstrate a gigahertz (GHz) harmonic mode-locked dual-pumped laser based on nonlinear multimode interference (NL-MMI), which is achieved by enhancing the nonlinearity and compensating the losses through pumping the hybrid NL-MMI saturable absorber (SA). A stable mode-locking was achieved with a pulse width of 0.66 ps and a repetition rate as high as 1.36 GHz, corresponding to the 66th harmonic of the fundamental frequency. Moreover, the threshold of mode-locking is effectively reduced through pumping the hybrid NL-MMI SA. This study provides a new concept and method for the design of low-threshold mode-locking and high-repetition-frequency lasers.
{"title":"GHz harmonic mode-locked dual-pumped laser based on nonlinear multimode interference","authors":"Ziyi Fu , Qi Xiao , Ruiqi Wang , Tianye Huang , Hongbo Zheng , Mingqi Fan , Jianxing Pan , Zhuo Cheng , Jing Zhang , Zhichao Wu , Xiang Li , Perry Ping Shum","doi":"10.1016/j.yofte.2026.104583","DOIUrl":"10.1016/j.yofte.2026.104583","url":null,"abstract":"<div><div>Ultrafast lasers can generate high-repetition-rate ultrashort pulses through various mode-locking mechanisms. However, research on generating high-repetition-rate pulses based on nonlinear multimode interference is still relatively limited. In this paper, we propose and demonstrate a gigahertz (GHz) harmonic mode-locked dual-pumped laser based on nonlinear multimode interference (NL-MMI), which is achieved by enhancing the nonlinearity and compensating the losses through pumping the hybrid NL-MMI saturable absorber (SA). A stable mode-locking was achieved with a pulse width of 0.66 ps and a repetition rate as high as 1.36 GHz, corresponding to the 66th harmonic of the fundamental frequency. Moreover, the threshold of mode-locking is effectively reduced through pumping the hybrid NL-MMI SA. This study provides a new concept and method for the design of low-threshold mode-locking and high-repetition-frequency lasers.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"99 ","pages":"Article 104583"},"PeriodicalIF":2.7,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-01-09DOI: 10.1016/j.yofte.2026.104554
Ruchi Srivastava , Yatindra Nath Singh
Multi-band elastic optical networks (MB-EONs) have emerged as a promising solution for enhancing transmission capacity by exploiting multiple spectral bands. However, when spectrum allocation is performed without wavelength conversion, a fundamental trade-off arises between spectral efficiency per connection and throughput per connection. Specifically, as additional spectral band combinations are introduced, the throughput per connection improves due to increased available bandwidth, whereas the spectral efficiency per connection degrades because of rigid spectrum and band continuity constraints. The first part of this study investigates this trade-off by evaluating the performance of different multi-band combinations under a without-wavelength-conversion (woC) spectrum allocation framework. To address the resulting loss in spectral efficiency, a wavelength-conversion-enabled (wC) spectrum allocation scheme is proposed, assuming the availability of wavelength converters at all network nodes. The proposed approach relaxes both spectrum and band continuity constraints, thereby enabling flexible per-link spectrum assignment while prioritizing the C-band during allocation. The C-band supports higher-order modulation formats and offers superior transmission characteristics. When combined with wavelength conversion, it allows different links along a path to independently select favorable modulation formats and spectral bands. This flexibility reduces the mean number of frequency slots (FSs) required per connection, which directly improves spectral efficiency across all considered spectral band combinations compared to the woC case. Simulation results obtained on the NSFNET and USNET topologies confirm that the wavelength-conversion-enabled allocation effectively enhances spectral efficiency by efficiently exploiting prioritized C-band resources. In particular, for the C+L band combination, the proposed scheme achieves an average spectral efficiency improvement of at least 0.6% compared to woC, albeit with a marginal reduction in throughput per connection.
{"title":"Spectrum allocation with wavelength conversion for enhanced spectral efficiency in multi-band elastic optical networks","authors":"Ruchi Srivastava , Yatindra Nath Singh","doi":"10.1016/j.yofte.2026.104554","DOIUrl":"10.1016/j.yofte.2026.104554","url":null,"abstract":"<div><div>Multi-band elastic optical networks (MB-EONs) have emerged as a promising solution for enhancing transmission capacity by exploiting multiple spectral bands. However, when spectrum allocation is performed without wavelength conversion, a fundamental trade-off arises between spectral efficiency per connection and throughput per connection. Specifically, as additional spectral band combinations are introduced, the throughput per connection improves due to increased available bandwidth, whereas the spectral efficiency per connection degrades because of rigid spectrum and band continuity constraints. The first part of this study investigates this trade-off by evaluating the performance of different multi-band combinations under a without-wavelength-conversion (woC) spectrum allocation framework. To address the resulting loss in spectral efficiency, a wavelength-conversion-enabled (wC) spectrum allocation scheme is proposed, assuming the availability of wavelength converters at all network nodes. The proposed approach relaxes both spectrum and band continuity constraints, thereby enabling flexible per-link spectrum assignment while prioritizing the C-band during allocation. The C-band supports higher-order modulation formats and offers superior transmission characteristics. When combined with wavelength conversion, it allows different links along a path to independently select favorable modulation formats and spectral bands. This flexibility reduces the mean number of frequency slots (FSs) required per connection, which directly improves spectral efficiency across all considered spectral band combinations compared to the woC case. Simulation results obtained on the NSFNET and USNET topologies confirm that the wavelength-conversion-enabled allocation effectively enhances spectral efficiency by efficiently exploiting prioritized C-band resources. In particular, for the C+L band combination, the proposed scheme achieves an average spectral efficiency improvement of at least 0.6% compared to woC, albeit with a marginal reduction in throughput per connection.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"98 ","pages":"Article 104554"},"PeriodicalIF":2.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145926940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-01-14DOI: 10.1016/j.yofte.2026.104551
Jin Li , Jie Liu , Wei Xu , Lisheng Liu , Guangpeng Zhou , Yaoyuan Zhang , Wenyu Wang , Yue Wang , Boyan Zhang , Jiangyong He , Zhi Wang , Rui Wang , Zhengwei Li
In this study, we observed the dynamic process of the mutual conversion between soliton and noise-like pulse in a spatiotemporal mode-locked fiber laser. Solitons and noise-like pulse exhibit distinct group velocity, and the conversion process is accompanied by energy absorption and release. Through simulation, we further achieved the mutual conversion between soliton and noise-like pulse. The research reveals that when energy fluctuates, mode competition causes the soliton power to increase. Affected by the reverse saturable absorption effect, the soliton transforms into a noise-like pulse. Accompanied by the energy release of the noise-like pulse, it returns to a stable soliton state. The results of our research are of great significance for a deeper understanding of the formation mechanism of noise-like pulse in spatiotemporal mode-locked fiber lasers.
{"title":"Dynamics of soliton and noise-like pulse conversion in spatiotemporal mode-locked fiber lasers","authors":"Jin Li , Jie Liu , Wei Xu , Lisheng Liu , Guangpeng Zhou , Yaoyuan Zhang , Wenyu Wang , Yue Wang , Boyan Zhang , Jiangyong He , Zhi Wang , Rui Wang , Zhengwei Li","doi":"10.1016/j.yofte.2026.104551","DOIUrl":"10.1016/j.yofte.2026.104551","url":null,"abstract":"<div><div>In this study, we observed the dynamic process of the mutual conversion between soliton and noise-like pulse in a spatiotemporal mode-locked fiber laser. Solitons and noise-like pulse exhibit distinct group velocity, and the conversion process is accompanied by energy absorption and release. Through simulation, we further achieved the mutual conversion between soliton and noise-like pulse. The research reveals that when energy fluctuates, mode competition causes the soliton power to increase. Affected by the reverse saturable absorption effect, the soliton transforms into a noise-like pulse. Accompanied by the energy release of the noise-like pulse, it returns to a stable soliton state. The results of our research are of great significance for a deeper understanding of the formation mechanism of noise-like pulse in spatiotemporal mode-locked fiber lasers.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"98 ","pages":"Article 104551"},"PeriodicalIF":2.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The vast extent of railway networks and their complex environmental dynamics pose significant challenges for traditional intrusion recognition methods. Fiber-optic distributed acoustic sensing (DAS) technology offers a promising solution due to its capabilities in distributed, long-distance, and continuous vibration monitoring. However, most existing research focuses on improving recognition accuracy under the closed-set assumption, overlooking the open-set nature of real-world scenarios and limiting practical applicability. To address this, we propose a novel open-set railway intrusion recognition method based on multi-task learning. Specifically, the closed-set classification and open-set rejection task branches share a common backbone feature extractor, while soft-attention modules are integrated into each task branch to extract task-specific features. Compared with conventional single-task open-set recognition methods, information sharing across tasks enhances the model’s generalization ability. Furthermore, the decoupled design of classification and rejection enables dedicated optimization and decision-making for each objective, improving both classification and rejection performance. Experimental results on railway field data demonstrate that the proposed method achieves an overall recognition accuracy of 92.43% and an AUROC of 0.9791, significantly outperforming traditional approaches and showcasing its substantial potential for railway intrusion recognition applications.
{"title":"Towards open-set intrusion recognition in railway environments: Multi-task learning meets fiber-optic distributed acoustic sensing","authors":"Yuewen Yin , Xiangqian Liu , Zhenshan Zhang , Hongze Xu","doi":"10.1016/j.yofte.2025.104542","DOIUrl":"10.1016/j.yofte.2025.104542","url":null,"abstract":"<div><div>The vast extent of railway networks and their complex environmental dynamics pose significant challenges for traditional intrusion recognition methods. Fiber-optic distributed acoustic sensing (DAS) technology offers a promising solution due to its capabilities in distributed, long-distance, and continuous vibration monitoring. However, most existing research focuses on improving recognition accuracy under the closed-set assumption, overlooking the open-set nature of real-world scenarios and limiting practical applicability. To address this, we propose a novel open-set railway intrusion recognition method based on multi-task learning. Specifically, the closed-set classification and open-set rejection task branches share a common backbone feature extractor, while soft-attention modules are integrated into each task branch to extract task-specific features. Compared with conventional single-task open-set recognition methods, information sharing across tasks enhances the model’s generalization ability. Furthermore, the decoupled design of classification and rejection enables dedicated optimization and decision-making for each objective, improving both classification and rejection performance. Experimental results on railway field data demonstrate that the proposed method achieves an overall recognition accuracy of 92.43% and an AUROC of 0.9791, significantly outperforming traditional approaches and showcasing its substantial potential for railway intrusion recognition applications.</div></div>","PeriodicalId":19663,"journal":{"name":"Optical Fiber Technology","volume":"98 ","pages":"Article 104542"},"PeriodicalIF":2.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145841807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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