Pub Date : 2025-10-14DOI: 10.1109/JLT.2025.3621219
Shihao Yan;Kai Chi;Xinyi Li;Ke Tian;Qinyi Li;Xin Wang;Elfed Lewis;Gerald Farrell;Pengfei Wang
In this article, we present a high-sensitivity strain sensor based on a femtosecond (fs) laser-inscribed groove-type multimode fiber (MMF) used as the center section of singlemode–multimode–singlemode (SMS) fiber structure. Unlike conventional SMS structures with homogeneous cylindrical MMFs, our design introduces multiple fs-laser-inscribed grooves into the MMF section, significantly enhancing strain sensitivity and also allowing for a more compact center section length of 10 mm. Simulation results indicate that the average mechanical strain within the groove-type MMF increases with groove depth. Experimental results further show that the strain sensitivity of the groove-type MMF formed SMS fiber structure reaches −21.23 pm/μϵ, representing a 10-fold improvement over a SMS fiber structure employing a non-grooved MMF (−2.04 pm/μϵ). Owing to its superior sensitivity and high fabrication precision, the proposed SMS fiber sensor shows good potential for high-accuracy strain measurement applications.
{"title":"High-Sensitivity Strain Sensor Based on Femtosecond Laser-Inscribed Groove- Type Multimode Fiber","authors":"Shihao Yan;Kai Chi;Xinyi Li;Ke Tian;Qinyi Li;Xin Wang;Elfed Lewis;Gerald Farrell;Pengfei Wang","doi":"10.1109/JLT.2025.3621219","DOIUrl":"https://doi.org/10.1109/JLT.2025.3621219","url":null,"abstract":"In this article, we present a high-sensitivity strain sensor based on a femtosecond (fs) laser-inscribed groove-type multimode fiber (MMF) used as the center section of singlemode–multimode–singlemode (SMS) fiber structure. Unlike conventional SMS structures with homogeneous cylindrical MMFs, our design introduces multiple fs-laser-inscribed grooves into the MMF section, significantly enhancing strain sensitivity and also allowing for a more compact center section length of 10 mm. Simulation results indicate that the average mechanical strain within the groove-type MMF increases with groove depth. Experimental results further show that the strain sensitivity of the groove-type MMF formed SMS fiber structure reaches −21.23 pm/μϵ, representing a 10-fold improvement over a SMS fiber structure employing a non-grooved MMF (−2.04 pm/μϵ). Owing to its superior sensitivity and high fabrication precision, the proposed SMS fiber sensor shows good potential for high-accuracy strain measurement applications.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"44 1","pages":"346-352"},"PeriodicalIF":4.8,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145814472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A leaky-wave meta-antenna (LWMA) is first proposed for high-gain co-aperture control of dual-band terahertz (THz) waves, where the meta-slots enable independent full-phase manipulation of two orthogonal waves at distinct frequencies. When used as a transmitting antenna, x- and y-polarized guided waves at the frequencies of 0.14 THz and 0.0972 THz, respectively, are coupled into the parallel-plate metal waveguide via two separate waveguide input ports. The two guided waves are manipulated simultaneously and independently by the meta-slots, enabling directional radiation through a shared aperture. The far-field gains are 35.1 dBi at 0.14 THz and 32 dBi at 0.0972 THz, with aperture efficiencies of 43.8% and 44.6%, respectively. The corresponding cross-polarization levels are –42.8 dB and –31.2 dB below the main lobes, and the isolation levels are as low as –31.3 dB and –31.1 dB. When operated in reverse as a receiving antenna, it converts the two orthogonally polarized incident beams into two-dimensional guided waves, which are then focused onto two distinct receiving ports. The gains at the focal points are 27 dB at 0.14 THz and 26.3 dB at 0.0972 THz. Both the measured far-field radiation patterns and intensity distributions on the focal planes agree well with the simulation results. The dual-band THz LWMA is promising for applications in sixth-generation mobile communications, radar detection, and imaging.
{"title":"A Dual-Band Terahertz Leaky-Wave Meta-Antenna","authors":"Yitao Ouyang;Yuanzhi Liu;Min Zhang;Hong Su;Yejun He;Huawei Liang","doi":"10.1109/JLT.2025.3620946","DOIUrl":"https://doi.org/10.1109/JLT.2025.3620946","url":null,"abstract":"A leaky-wave meta-antenna (LWMA) is first proposed for high-gain co-aperture control of dual-band terahertz (THz) waves, where the meta-slots enable independent full-phase manipulation of two orthogonal waves at distinct frequencies. When used as a transmitting antenna, <italic>x</i>- and <italic>y</i>-polarized guided waves at the frequencies of 0.14 THz and 0.0972 THz, respectively, are coupled into the parallel-plate metal waveguide via two separate waveguide input ports. The two guided waves are manipulated simultaneously and independently by the meta-slots, enabling directional radiation through a shared aperture. The far-field gains are 35.1 dBi at 0.14 THz and 32 dBi at 0.0972 THz, with aperture efficiencies of 43.8% and 44.6%, respectively. The corresponding cross-polarization levels are –42.8 dB and –31.2 dB below the main lobes, and the isolation levels are as low as –31.3 dB and –31.1 dB. When operated in reverse as a receiving antenna, it converts the two orthogonally polarized incident beams into two-dimensional guided waves, which are then focused onto two distinct receiving ports. The gains at the focal points are 27 dB at 0.14 THz and 26.3 dB at 0.0972 THz. Both the measured far-field radiation patterns and intensity distributions on the focal planes agree well with the simulation results. The dual-band THz LWMA is promising for applications in sixth-generation mobile communications, radar detection, and imaging.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"43 24","pages":"11002-11012"},"PeriodicalIF":4.8,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145674775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-10-10DOI: 10.1109/JLT.2025.3620111
Masashi Kikuchi;Takayoshi Mori;Yusuke Yamada
We propose a high-density cable for controlling differential modal delay (DMD) by using the curvature induced within the cable structure to achieve zero-DMD with low optical loss for arbitrary 2-linearly polarized (LP)-mode graded-index optical fiber. We also present a theoretical model for controlling the curvature of optical fiber to control DMD and clarify, on the basis of the theoretical model, that increasing the diameter of the optical fiber unit enhances DMD controllability and reduces the increase in optical loss. We numerically investigate the curvature to achieve zero-DMD with an arbitrary profile exponent and trench depth of 2-LP-mode graded-index optical fiber. We validate the model by fabricating high-density cables with curvature control and experimentally measuring fiber curvature, DMD, and optical loss. On the basis of these analyses, we identify optimal cable-design parameters that achieve a target fiber curvature with minimal lateral pressure by deriving the relationship between bundle tension, unit diameter, and induced fiber curvature.
{"title":"High-Density Cables for Controlling Differential Modal Delay of 2-LP-Mode Graded-Index Optical Fiber","authors":"Masashi Kikuchi;Takayoshi Mori;Yusuke Yamada","doi":"10.1109/JLT.2025.3620111","DOIUrl":"https://doi.org/10.1109/JLT.2025.3620111","url":null,"abstract":"We propose a high-density cable for controlling differential modal delay (DMD) by using the curvature induced within the cable structure to achieve zero-DMD with low optical loss for arbitrary 2-linearly polarized (LP)-mode graded-index optical fiber. We also present a theoretical model for controlling the curvature of optical fiber to control DMD and clarify, on the basis of the theoretical model, that increasing the diameter of the optical fiber unit enhances DMD controllability and reduces the increase in optical loss. We numerically investigate the curvature to achieve zero-DMD with an arbitrary profile exponent and trench depth of 2-LP-mode graded-index optical fiber. We validate the model by fabricating high-density cables with curvature control and experimentally measuring fiber curvature, DMD, and optical loss. On the basis of these analyses, we identify optimal cable-design parameters that achieve a target fiber curvature with minimal lateral pressure by deriving the relationship between bundle tension, unit diameter, and induced fiber curvature.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"43 24","pages":"11074-11080"},"PeriodicalIF":4.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145665837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-10-10DOI: 10.1109/JLT.2025.3620218
Arthur Poiffaut;Olivier Bélanger;Jean-Sébastien Boisvert;Martin Poinsinet De Sivry-Houle;Rodrigo Itzamná Becerra-Deana;Caroline Boudoux;Sébastien Loranger
We propose a simple and cost-effective distributed force sensing technique based on intermodal coupling in polarization-maintaining few-mode fibers. A broadband linearly polarized optical source is injected into a single-mode-few-mode-single-mode fiber structure, and the resulting interferometric signal is analyzed using an optical spectrum analyzer. Localized external perturbations are detected via the induced coupling to higher-order modes, with spatial information extracted through Fourier-domain analysis of the spectrum, in a manner similar to optical frequency domain reflectometry. Experimental results demonstrate a spatial resolution of 8 cm of a maximum of 38 m sensing length, directional sensitivity, and the capability to resolve multiple force points along meter-scale fiber lengths. Transverse forces ranging from 0.65 N to 3.8 N have been tested, yielding a measurement precision of approximately 0.03 N. This technique offers a compact, temperature-independent method for real-time monitoring, providing an alternative to conventional distributed sensing methods.
{"title":"Distributed Directional Force Sensing in Few-Mode Polarization-Maintaining Fibers via Low-Coherence Interferometry","authors":"Arthur Poiffaut;Olivier Bélanger;Jean-Sébastien Boisvert;Martin Poinsinet De Sivry-Houle;Rodrigo Itzamná Becerra-Deana;Caroline Boudoux;Sébastien Loranger","doi":"10.1109/JLT.2025.3620218","DOIUrl":"https://doi.org/10.1109/JLT.2025.3620218","url":null,"abstract":"We propose a simple and cost-effective distributed force sensing technique based on intermodal coupling in polarization-maintaining few-mode fibers. A broadband linearly polarized optical source is injected into a single-mode-few-mode-single-mode fiber structure, and the resulting interferometric signal is analyzed using an optical spectrum analyzer. Localized external perturbations are detected via the induced coupling to higher-order modes, with spatial information extracted through Fourier-domain analysis of the spectrum, in a manner similar to optical frequency domain reflectometry. Experimental results demonstrate a spatial resolution of 8 cm of a maximum of 38 m sensing length, directional sensitivity, and the capability to resolve multiple force points along meter-scale fiber lengths. Transverse forces ranging from 0.65 N to 3.8 N have been tested, yielding a measurement precision of approximately 0.03 N. This technique offers a compact, temperature-independent method for real-time monitoring, providing an alternative to conventional distributed sensing methods.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"43 24","pages":"11146-11151"},"PeriodicalIF":4.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11199866","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145665809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We demonstrate a four-core erbium-doped fiber amplifier designed for multi-core bidirectional transmission. By using a double-layered planar lightwave circuit with a built-in pump light combiner, we achieved a fan-in/fan-out-less isolator-shared configuration. C-band optical amplification with an average gain of 15.5 dB and a noise figure of 6.8 dB was achieved at the input signal power per core of 0 dBm. Our results demonstrate that the influence of the difference between up- and down-link input signal powers on the amplification performance can be managed by means of pump power control. However, we also found that a difference of more than 2 dB in the up- and down-link input signal power may have a negative effect on the power conversion efficiency.
{"title":"Four-Core Erbium-Doped Fiber Amplifier for Bi-Directional Transmission Using PLC-Type Directional Convertor","authors":"Masaki Wada;Taiji Sakamoto;Takashi Matsui;Kazuhide Nakajima","doi":"10.1109/JLT.2025.3619987","DOIUrl":"https://doi.org/10.1109/JLT.2025.3619987","url":null,"abstract":"We demonstrate a four-core erbium-doped fiber amplifier designed for multi-core bidirectional transmission. By using a double-layered planar lightwave circuit with a built-in pump light combiner, we achieved a fan-in/fan-out-less isolator-shared configuration. C-band optical amplification with an average gain of 15.5 dB and a noise figure of 6.8 dB was achieved at the input signal power per core of 0 dBm. Our results demonstrate that the influence of the difference between up- and down-link input signal powers on the amplification performance can be managed by means of pump power control. However, we also found that a difference of more than 2 dB in the up- and down-link input signal power may have a negative effect on the power conversion efficiency.","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"43 24","pages":"11043-11048"},"PeriodicalIF":4.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145665829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-10-09DOI: 10.1109/JLT.2025.3616695
{"title":"Journal of Lightwave Technology Information for Authors","authors":"","doi":"10.1109/JLT.2025.3616695","DOIUrl":"https://doi.org/10.1109/JLT.2025.3616695","url":null,"abstract":"","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"43 20","pages":"C3-C3"},"PeriodicalIF":4.8,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11197736","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-09DOI: 10.1109/JLT.2025.3616671
{"title":"Journal of Lightwave Technology Information for Authors","authors":"","doi":"10.1109/JLT.2025.3616671","DOIUrl":"https://doi.org/10.1109/JLT.2025.3616671","url":null,"abstract":"","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"43 17","pages":"C3-C3"},"PeriodicalIF":4.8,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11197702","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-09DOI: 10.1109/JLT.2025.3616679
{"title":"Journal of Lightwave Technology Information for Authors","authors":"","doi":"10.1109/JLT.2025.3616679","DOIUrl":"https://doi.org/10.1109/JLT.2025.3616679","url":null,"abstract":"","PeriodicalId":16144,"journal":{"name":"Journal of Lightwave Technology","volume":"43 18","pages":"C3-C3"},"PeriodicalIF":4.8,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11197670","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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