Curvature sensing is essential in robotics, aerospace, and structural health monitoring, where precise deformation measurements are critical. However, existing curvature sensing technologies—such as strain gauges, inertial measurement units, and various fiber-optic approaches—suffer from limitations including electromagnetic interference, bulky form factors, low spatial resolution, temperature drift, complex fabrication, and restricted measurement ranges, especially for large-curvature and full-direction recognition. Here, we present a Michelson interferometer (MI)-based fiber curvature sensor composed of single-mode fiber, multimode fiber, and three-core fiber (SMF–MMF–TCF). The spatially distributed cores of the TCF inherently provide a directional reference, eliminating the need for inscribed gratings or asymmetric cladding, and enabling ultra-wide curvature measurement from 0 to 5.49 m−1 with a maximum directional sensitivity of 1.07 dB/m−1. Experimental results reveal a sinusoidal curvature sensitivity pattern, allowing precise bending angle recognition with excellent linearity (R2 > 0.98) even at maximum curvature. The temperature sensitivity is −0.073 dB/°C within the temperature range of 25–95 °C, and the corresponding temperature cross-sensitivity is −0.068 m−1/°C, indicating that the proposed sensor exhibits reliable curvature sensing performance in the presence of moderate temperature fluctuations. This plug-and-play design, requiring only simple fusion splicing, offers a low-cost, high-performance, and robust solution for full 360° vector curvature sensing, paving the way for practical deployment in demanding industrial applications.
{"title":"Compact Optical Fiber Directional Curvature Sensor With Large Curvature Range Based on Michelson Interferometer","authors":"Zuoxin Wang;Haojie Zhang;Zhongwei Cao;Zhiguo Zhang","doi":"10.1109/JPHOT.2026.3656017","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3656017","url":null,"abstract":"Curvature sensing is essential in robotics, aerospace, and structural health monitoring, where precise deformation measurements are critical. However, existing curvature sensing technologies—such as strain gauges, inertial measurement units, and various fiber-optic approaches—suffer from limitations including electromagnetic interference, bulky form factors, low spatial resolution, temperature drift, complex fabrication, and restricted measurement ranges, especially for large-curvature and full-direction recognition. Here, we present a Michelson interferometer (MI)-based fiber curvature sensor composed of single-mode fiber, multimode fiber, and three-core fiber (SMF–MMF–TCF). The spatially distributed cores of the TCF inherently provide a directional reference, eliminating the need for inscribed gratings or asymmetric cladding, and enabling ultra-wide curvature measurement from 0 to 5.49 m<sup>−1</sup> with a maximum directional sensitivity of 1.07 dB/m<sup>−1</sup>. Experimental results reveal a sinusoidal curvature sensitivity pattern, allowing precise bending angle recognition with excellent linearity (R<sup>2</sup> > 0.98) even at maximum curvature. The temperature sensitivity is −0.073 dB/°C within the temperature range of 25–95 °C, and the corresponding temperature cross-sensitivity is −0.068 m<sup>−1</sup>/°C, indicating that the proposed sensor exhibits reliable curvature sensing performance in the presence of moderate temperature fluctuations. This plug-and-play design, requiring only simple fusion splicing, offers a low-cost, high-performance, and robust solution for full 360° vector curvature sensing, paving the way for practical deployment in demanding industrial applications.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-8"},"PeriodicalIF":2.4,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11359502","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The output power of fiber lasers with narrow-linewidth is typically limited by stimulated Brillouin scattering (SBS). Spectral broadening via phase modulation is preferred to suppress SBS, but its capability approaches the limit for a given linewidth and modulation signal. Nonlinear phase demodulation based on self-phase modulation (SPM) is able to break through the SBS limit of the phase modulation scheme for further power scaling with narrow linewidth. In this paper, an analytic model of nonlinear phase demodulation is developed to investigate the influence of modulation parameters and output power on spectral evolution. By using this scheme, we realize a 2.35 kW single mode all-fiber amplifier with a full width of half maximum (FWHM) linewidth of 4.68 GHz. The power spectral density (PSD) reaches up to 502.14 W/GHz. Compared to single pseudo-random binary sequence (PRBS) phase modulation, the SBS threshold is enhanced by a factor of 1.44. The nonlinear phase demodulation scheme combining phase modulation has significant potential for achieving higher-power continuous wave (CW) or pulsed fiber lasers with narrow linewidth.
{"title":"4.68 GHz, 2.35 kW Single Mode All-Fiber Amplifier Using Nonlinear Phase Demodulation for SBS Suppression and Spectral Compression","authors":"Mengqi Zhang;Hui Shen;Jinwei Xie;Chuanfa Jia;Zhao Quan;Tao Liu;Yunfeng Qi;Lei Zhang;Chunlei Yu","doi":"10.1109/JPHOT.2026.3656230","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3656230","url":null,"abstract":"The output power of fiber lasers with narrow-linewidth is typically limited by stimulated Brillouin scattering (SBS). Spectral broadening via phase modulation is preferred to suppress SBS, but its capability approaches the limit for a given linewidth and modulation signal. Nonlinear phase demodulation based on self-phase modulation (SPM) is able to break through the SBS limit of the phase modulation scheme for further power scaling with narrow linewidth. In this paper, an analytic model of nonlinear phase demodulation is developed to investigate the influence of modulation parameters and output power on spectral evolution. By using this scheme, we realize a 2.35 kW single mode all-fiber amplifier with a full width of half maximum (FWHM) linewidth of 4.68 GHz. The power spectral density (PSD) reaches up to 502.14 W/GHz. Compared to single pseudo-random binary sequence (PRBS) phase modulation, the SBS threshold is enhanced by a factor of 1.44. The nonlinear phase demodulation scheme combining phase modulation has significant potential for achieving higher-power continuous wave (CW) or pulsed fiber lasers with narrow linewidth.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-7"},"PeriodicalIF":2.4,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11359513","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a domain decomposition finite element method (DD-FEM) to accelerate topology optimization of photonic devices. In the proposed approach, the structure invariant region is precomputed and transformed into a reduced boundary conditions for the design region, allowing only the design region to be reanalyzed during optimization. The applicability of the method is demonstrated through the analysis and optimal design of a matching coupler between a strip waveguide and a subwavelength-grating (SWG) waveguide, as well as a waveguide lens. Under the same optimization settings, DD-FEM reduces the computational time per-analysis by approximately a factor of 2–3 and the memory requirement to about one third of that of a standard FEM analysis, making it particularly advantageous when the design region is small relative to the overall computational domain. In addition, we investigate a thresholding method for the dense interface matrix, where small nonzero entries are discarded to further reduce the computational cost of DD-FEM. If an error of about 0.5% in transmitted-power evaluation is acceptable, the linear-system solving time can be reduced to approximately 77% of that without thresholding.
{"title":"Efficient Topology Optimization of Photonic Devices Using Domain Decomposition Finite Element Method","authors":"Fangming He;Taiki Matsuzaki;Akito Iguchi;Yasuhide Tsuji;Takeshi Fujisawa","doi":"10.1109/JPHOT.2026.3655434","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3655434","url":null,"abstract":"This paper presents a domain decomposition finite element method (DD-FEM) to accelerate topology optimization of photonic devices. In the proposed approach, the structure invariant region is precomputed and transformed into a reduced boundary conditions for the design region, allowing only the design region to be reanalyzed during optimization. The applicability of the method is demonstrated through the analysis and optimal design of a matching coupler between a strip waveguide and a subwavelength-grating (SWG) waveguide, as well as a waveguide lens. Under the same optimization settings, DD-FEM reduces the computational time per-analysis by approximately a factor of 2–3 and the memory requirement to about one third of that of a standard FEM analysis, making it particularly advantageous when the design region is small relative to the overall computational domain. In addition, we investigate a thresholding method for the dense interface matrix, where small nonzero entries are discarded to further reduce the computational cost of DD-FEM. If an error of about 0.5% in transmitted-power evaluation is acceptable, the linear-system solving time can be reduced to approximately 77% of that without thresholding.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-7"},"PeriodicalIF":2.4,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11358688","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Long-wave infrared (LWIR) imaging is increasingly required in night vision, compact aerial platforms, and wearable systems, where the demand for lightweight and low-cost optics challenges traditional multi-element refractive lenses. Although metalenses offer strong miniaturization potential, their standalone bandwidth and wide-FOV performance remain constrained. To address these limitations, we propose a target-driven, phase-gradient-aware ring-by-ring optimization for designing an achromatic and coma-corrected LWIR hybrid metalens with an 8.4 mm diameter. The refractive geometry and wavelength-dependent metalens phase compensation is jointly optimized across the 8-12 μm band and a 41.4° full field of view. The resulting hybrid system, with a total track length of only 15.8 mm, delivers diffraction-limited focal spots with very small chromatic focal shifts, well-suppressed off-axis aberrations, and an MTF exceeding 0.37 at 20 lp/mm. Resolution-target imaging further demonstrates substantially clearer feature reproduction than a refractive-only lens. These results establish a viable route toward compact, lightweight, and high-performance LWIR imaging systems.
{"title":"Target-Driven Ring-by-Ring Optimization of an Achromatic and Coma-Corrected Long-Wave Infrared Hybrid Metalens for Large Field of View Imaging","authors":"Xuyong You;Ruirui Zhang;Ziqi Liu;Helun Song;Shuxian Li;Wei Huang","doi":"10.1109/JPHOT.2026.3654923","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3654923","url":null,"abstract":"Long-wave infrared (LWIR) imaging is increasingly required in night vision, compact aerial platforms, and wearable systems, where the demand for lightweight and low-cost optics challenges traditional multi-element refractive lenses. Although metalenses offer strong miniaturization potential, their standalone bandwidth and wide-FOV performance remain constrained. To address these limitations, we propose a target-driven, phase-gradient-aware ring-by-ring optimization for designing an achromatic and coma-corrected LWIR hybrid metalens with an 8.4 mm diameter. The refractive geometry and wavelength-dependent metalens phase compensation is jointly optimized across the 8-12 μm band and a 41.4° full field of view. The resulting hybrid system, with a total track length of only 15.8 mm, delivers diffraction-limited focal spots with very small chromatic focal shifts, well-suppressed off-axis aberrations, and an MTF exceeding 0.37 at 20 lp/mm. Resolution-target imaging further demonstrates substantially clearer feature reproduction than a refractive-only lens. These results establish a viable route toward compact, lightweight, and high-performance LWIR imaging systems.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-6"},"PeriodicalIF":2.4,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11355921","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Surface modification of titanium (Ti) and titanium alloy (Ti6Al4V) for medical implants is frequently required to improve material characteristics and reduce predisposing factors to bacterial invasion and infection. In case of dental abutments, due to close contact of the material with peri-implant soft tissue, it is expected that the surface supports gingival cell adhesion while preventing bacterial diffusion at the interface. Laser surface texturing has demonstrated the possibility to fabricate micro- and nanostructures on large-scale surfaces of various materials with new characteristics and functionalities. Here, we demonstrate the possibility to generate large-scale laser-induced periodic surface structures (LIPSS) by picosecond laser-texturing of Ti and Ti6Al4V surfaces, in a contamination-free approach. Uniform LIPSS formation is confirmed by morpho-chemical analyses using a scanning electron microscopy and a scanning near-field optical microscopy. The behavior of primary human gingival epithelial cells (hGEpiCs) and gingival fibroblast cells (hGFCs) on laser-modified surfaces was evaluated to assess samples biocompatibility. It was shown that LIPSS fabricated on titanium substrates promote more favorable cellular response, including better cell attachment and higher proliferation rates of hGEpiCs. Meanwhile, LIPSS on Ti6Al4V surfaces enhance hGFCs adhesion and proliferation which is essential for improving tissue healing around dental implants. Moreover, laser texturing on Ti6Al4V surfaces induces lower expression of alpha-SMA protein which is associated with fibrosis development, showing positive implications for peri-implant soft tissue integration in implantology.
{"title":"Fabrication, s-SNOM Characterization and in vitro Testing of Laser-Induced Periodic Surface Structures for Dental Abutment Applications","authors":"Paula Florian;Madalina Icriverzi;Florin Jipa;Adrian Cernescu;Gianina Popescu-Pelin;Roxana Eliss Budei;Dragos Budei;Emanuel Axente;Koji Sugioka;Felix Sima","doi":"10.1109/JPHOT.2026.3654754","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3654754","url":null,"abstract":"Surface modification of titanium (Ti) and titanium alloy (Ti6Al4V) for medical implants is frequently required to improve material characteristics and reduce predisposing factors to bacterial invasion and infection. In case of dental abutments, due to close contact of the material with peri-implant soft tissue, it is expected that the surface supports gingival cell adhesion while preventing bacterial diffusion at the interface. Laser surface texturing has demonstrated the possibility to fabricate micro- and nanostructures on large-scale surfaces of various materials with new characteristics and functionalities. Here, we demonstrate the possibility to generate large-scale laser-induced periodic surface structures (LIPSS) by picosecond laser-texturing of Ti and Ti6Al4V surfaces, in a contamination-free approach. Uniform LIPSS formation is confirmed by morpho-chemical analyses using a scanning electron microscopy and a scanning near-field optical microscopy. The behavior of primary human gingival epithelial cells (hGEpiCs) and gingival fibroblast cells (hGFCs) on laser-modified surfaces was evaluated to assess samples biocompatibility. It was shown that LIPSS fabricated on titanium substrates promote more favorable cellular response, including better cell attachment and higher proliferation rates of hGEpiCs. Meanwhile, LIPSS on Ti6Al4V surfaces enhance hGFCs adhesion and proliferation which is essential for improving tissue healing around dental implants. Moreover, laser texturing on Ti6Al4V surfaces induces lower expression of alpha-SMA protein which is associated with fibrosis development, showing positive implications for peri-implant soft tissue integration in implantology.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-13"},"PeriodicalIF":2.4,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11355956","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The sub-wavelength grating NRD guide (SWG-NRD guide) can transmit the single LSM$_{01}$ mode regardless of arbitrary bends without exciting the LSE$_{01}$ mode, unlike the standard NRD guide, making it a promising candidate in developing THz-wave integrated circuits. The simple bending waveguides and power-splitting devices with sharp curvature have been previously investigated on this platform; however, more sophisticated devices with arbitrary bends have yet to be thoroughly examined. This paper presents the design of a SWG-NRD 3-dB wavelength-insensitive coupler (WINC) based on Mach-Zehnder interferometer (MZI) with arbitrary bends, utilizing the topology-optimized matching circuit. The WINC achieves a broadband operational range from 0.93 THz to 1.06 THz with an imbalance of less than $pm$ 0.5 dB and an average coupling ratio of 49.2%. The average return loss and isolation are better than $-$ 21 dB and $-$ 24 dB, respectively, and the average insertion loss is only 0.089 dB. To demonstrate the usefulness of the WINC, a design of an MZI interleaver is presented. The tolerance for fabrication errors in the proposed devices is also thoroughly discussed. The designed devices do not experience LSE$_{01}$ mode excitation at the bends, confirming the platform's relevance and devices' possible application in THz integrated wavelength-division multiplexing (WDM) systems.
{"title":"Study on MZI-Based Advanced SWG-NRD Guide Terahertz Devices Using Topology-Optimized Matching Circuit","authors":"Md. Iquebal Hossain Patwary;Tahir Bashir;Akito Iguchi;Yasuhide Tsuji","doi":"10.1109/JPHOT.2026.3653722","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3653722","url":null,"abstract":"The sub-wavelength grating NRD guide (SWG-NRD guide) can transmit the single LSM<inline-formula><tex-math>$_{01}$</tex-math></inline-formula> mode regardless of arbitrary bends without exciting the LSE<inline-formula><tex-math>$_{01}$</tex-math></inline-formula> mode, unlike the standard NRD guide, making it a promising candidate in developing THz-wave integrated circuits. The simple bending waveguides and power-splitting devices with sharp curvature have been previously investigated on this platform; however, more sophisticated devices with arbitrary bends have yet to be thoroughly examined. This paper presents the design of a SWG-NRD 3-dB wavelength-insensitive coupler (WINC) based on Mach-Zehnder interferometer (MZI) with arbitrary bends, utilizing the topology-optimized matching circuit. The WINC achieves a broadband operational range from 0.93 THz to 1.06 THz with an imbalance of less than <inline-formula><tex-math>$pm$</tex-math></inline-formula> 0.5 dB and an average coupling ratio of 49.2%. The average return loss and isolation are better than <inline-formula><tex-math>$-$</tex-math></inline-formula> 21 dB and <inline-formula><tex-math>$-$</tex-math></inline-formula> 24 dB, respectively, and the average insertion loss is only 0.089 dB. To demonstrate the usefulness of the WINC, a design of an MZI interleaver is presented. The tolerance for fabrication errors in the proposed devices is also thoroughly discussed. The designed devices do not experience LSE<inline-formula><tex-math>$_{01}$</tex-math></inline-formula> mode excitation at the bends, confirming the platform's relevance and devices' possible application in THz integrated wavelength-division multiplexing (WDM) systems.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-9"},"PeriodicalIF":2.4,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11348059","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-01-13DOI: 10.1109/JPHOT.2026.3653792
Tonglu Xing;Hua Tao;Cheng Liu;Jianqiang Zhu
Conjugate image is an inherent problem of coherent diffraction imaging (CDI) and direct analysis and research on them have long been incomplete. By writing diffraction intensities into linear equation set, it was demonstrated that the fundamental mathematical reason for the generation of conjugate image lies on the real-value coefficients of these linear equations, and then the conjugate image could be eliminated by adopting optical alignments that can lead to complex–value coefficients. While theoretical analysis was proposed its feasibility was verified both numerically and experimentally. The study provides new insights into the physical mechanism of CDI and new strategies to improve the image quality of other phase retrieval techniques.
{"title":"Study on the Generation and Elimination of Conjugate Image in Coherent Different Imaging","authors":"Tonglu Xing;Hua Tao;Cheng Liu;Jianqiang Zhu","doi":"10.1109/JPHOT.2026.3653792","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3653792","url":null,"abstract":"Conjugate image is an inherent problem of coherent diffraction imaging (CDI) and direct analysis and research on them have long been incomplete. By writing diffraction intensities into linear equation set, it was demonstrated that the fundamental mathematical reason for the generation of conjugate image lies on the real-value coefficients of these linear equations, and then the conjugate image could be eliminated by adopting optical alignments that can lead to complex–value coefficients. While theoretical analysis was proposed its feasibility was verified both numerically and experimentally. The study provides new insights into the physical mechanism of CDI and new strategies to improve the image quality of other phase retrieval techniques.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 2","pages":"1-8"},"PeriodicalIF":2.4,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11348091","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-01-12DOI: 10.1109/JPHOT.2026.3651843
Dongqin Guo;Gang Xin;Qi Wu;Jian Zhang
To improve the security performance of Visible Light Communications (VLC) systems, this paper explores a novel secure scheme that incorporates reconfigurable intelligent surfaces (RIS) and jamming technologies. Specifically, the system includes a transmitter, a legitimate user who can control the jamming, and an eavesdropper. In addition, a mirror array-based RIS (mRIS) is arranged on the wall of the room. Adjusting the configuration of the mRIS units enables the reshaping of the channel environment, thereby improving the system’s secrecy rate. Then, a secrecy rate maximization problem is formulated. To address the proposed optimization problem, a genetic algorithm-based (GA)-based optimization algorithm is put forward. Simulation results demonstrate that the proposed VLC security system, combined with the optimization algorithm, can effectively enhance the system’s security performance.
{"title":"RIS-Aided Physical Layer Security for Visible Light Communication Systems","authors":"Dongqin Guo;Gang Xin;Qi Wu;Jian Zhang","doi":"10.1109/JPHOT.2026.3651843","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3651843","url":null,"abstract":"To improve the security performance of Visible Light Communications (VLC) systems, this paper explores a novel secure scheme that incorporates reconfigurable intelligent surfaces (RIS) and jamming technologies. Specifically, the system includes a transmitter, a legitimate user who can control the jamming, and an eavesdropper. In addition, a mirror array-based RIS (mRIS) is arranged on the wall of the room. Adjusting the configuration of the mRIS units enables the reshaping of the channel environment, thereby improving the system’s secrecy rate. Then, a secrecy rate maximization problem is formulated. To address the proposed optimization problem, a genetic algorithm-based (GA)-based optimization algorithm is put forward. Simulation results demonstrate that the proposed VLC security system, combined with the optimization algorithm, can effectively enhance the system’s security performance.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 1","pages":"1-6"},"PeriodicalIF":2.4,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11340672","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-01-12DOI: 10.1109/JPHOT.2026.3652318
Ryotaro Harada;Akihiro Maruta;Ken Mishina
Multilevel modulation schemes based on the inverse scattering transform (IST) are some of the promising technologies for achieving a significant advancement in transmission capacity within optical fiber communication systems overcoming the nonlinear Shannon limit. Despite the recognized potential of multilevel modulation using the scattering coefficient $b$ to enhance the transmission capacity, previous studies assumed that the distributions of eigenvalues and $b$ follow a Gaussian distribution for the signal point assignment. Because the distributions of eigenvalues and $b$ do not exactly follow a Gaussian distribution, signal design considering these distributions is to be studied. In this paper, we propose a novel signal point arrangement method for the $b$-modulation considering the distribution to maximize transmission capacity. The amplitude and argument of $b$ correspond to the temporal center position $T_{c}$ and phase $theta$ of the soliton component, respectively. Therefore, we arrange the signal points of the $b$-modulation after converting the coefficient $b$ from the $b$-plane to the $T_{c}$-$theta$ -plane in this paper. Through numerical simulations in the back-to-back configuration, we demonstrate that the proposed method improves the bit error rate (BER) performance by approximately 10–12dB compared with a conventional signal point assignment method such as QAM. Moreover, the result of the transmission simulation demonstrates that the proposed method can extend the achievable transmission distance by 1000–3000 km. Furthermore, by performing the analysis of the noise characteristics of $b$ on the $T_{c}$-$theta$-plane, the estimation accuracy of the generalized mutual information can be improved in the $b$ modulation scheme.
{"title":"Design and Analysis for Multilevel-Modulated Signal Using the Scattering Coefficient $b$ in Inverse Scattering Transform","authors":"Ryotaro Harada;Akihiro Maruta;Ken Mishina","doi":"10.1109/JPHOT.2026.3652318","DOIUrl":"https://doi.org/10.1109/JPHOT.2026.3652318","url":null,"abstract":"Multilevel modulation schemes based on the inverse scattering transform (IST) are some of the promising technologies for achieving a significant advancement in transmission capacity within optical fiber communication systems overcoming the nonlinear Shannon limit. Despite the recognized potential of multilevel modulation using the scattering coefficient <inline-formula><tex-math>$b$</tex-math></inline-formula> to enhance the transmission capacity, previous studies assumed that the distributions of eigenvalues and <inline-formula><tex-math>$b$</tex-math></inline-formula> follow a Gaussian distribution for the signal point assignment. Because the distributions of eigenvalues and <inline-formula><tex-math>$b$</tex-math></inline-formula> do not exactly follow a Gaussian distribution, signal design considering these distributions is to be studied. In this paper, we propose a novel signal point arrangement method for the <inline-formula><tex-math>$b$</tex-math></inline-formula>-modulation considering the distribution to maximize transmission capacity. The amplitude and argument of <inline-formula><tex-math>$b$</tex-math></inline-formula> correspond to the temporal center position <inline-formula><tex-math>$T_{c}$</tex-math></inline-formula> and phase <inline-formula><tex-math>$theta$</tex-math></inline-formula> of the soliton component, respectively. Therefore, we arrange the signal points of the <inline-formula><tex-math>$b$</tex-math></inline-formula>-modulation after converting the coefficient <inline-formula><tex-math>$b$</tex-math></inline-formula> from the <inline-formula><tex-math>$b$</tex-math></inline-formula>-plane to the <inline-formula><tex-math>$T_{c}$</tex-math></inline-formula>-<inline-formula><tex-math>$theta$</tex-math></inline-formula> -plane in this paper. Through numerical simulations in the back-to-back configuration, we demonstrate that the proposed method improves the bit error rate (BER) performance by approximately 10–12dB compared with a conventional signal point assignment method such as QAM. Moreover, the result of the transmission simulation demonstrates that the proposed method can extend the achievable transmission distance by 1000–3000 km. Furthermore, by performing the analysis of the noise characteristics of <inline-formula><tex-math>$b$</tex-math></inline-formula> on the <inline-formula><tex-math>$T_{c}$</tex-math></inline-formula>-<inline-formula><tex-math>$theta$</tex-math></inline-formula>-plane, the estimation accuracy of the generalized mutual information can be improved in the <inline-formula><tex-math>$b$</tex-math></inline-formula> modulation scheme.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"18 1","pages":"1-13"},"PeriodicalIF":2.4,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11339870","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2026-01-12DOI: 10.1109/JPHOT.2026.3652683
Ziming Dong;Yuqing Zhao;Guoqing Sun;Yaxin Wang;Lei Ding;Liqin Tang;Yigang Li
Integrated optical waveguide amplifiers outperform in terms of compact footprint and low power consumption in a scalable manner, serving as the foundation for optical communications and laser technology. The realization of high gain for such integrated devices is made more challenging by tight optical confinement and low propagation loss. In this work, we present efficient amplification in erbium-ytterbium-based heterogeneous paperclip slot waveguide via silicon nitride photonics integrated circuits. By carefully designing a heterogeneous device using optical mode propagation and dispersion engineering, this heterostructure features a low propagation loss and high single-mode conservation at 1530 nm. A comprehensive erbium-ytterbium co-doped amplifier dynamic modeling is established by introducing a quenching process, which further optimizes the parameters to improve the amplifier performance. The simulation results demonstrate that a heterogeneous paperclip slot waveguide can potentially achieve up to 27 dB/cm modal gain per unit length. This work provides a predictive design framework for endowing silicon nitride photonic integrated circuits with efficient amplification and enriches the integration of active functionalities on silicon.
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