This letter proposes a dual-track encryption scheme for ciphertext and key based on dynamic window perturbation, enabling highly secure information transmission in both the key and ciphertext dimensions. For key encryption, a modular exponentiation iteration algorithm is used to process the chaotic initial value key, which not only reduces the risk of key leakage but also expands the key space to $10^{99}$ . For ciphertext encryption, a three-dimensional Lorenz chaotic map is used to generate decision factors. Symbols are grouped according to dynamic window sizes, and each group is perturbed and encrypted based on the decision factors. The core advantage of the scheme lies in its symbol-level dynamic grouping encryption mechanism. Unlike traditional bit-level encryption, this scheme avoids the overhead of encrypting each symbol individually by applying dynamic window perturbation to symbol groups, reducing time costs by approximately 50% and more than doubling efficiency. In the 2 kilometer seven-core fiber experiment, the scheme achieved an encrypted signal transmission rate of 110.74 Gb/s, with all fiber cores meeting the hard-decision forward error correction (FEC) bit error rate (BER) threshold of $3.8{,}times{,}10^{-3}$ . Experimental results demonstrate that even in cases of partial key leakage or key misalignment at an unauthorized receiver, the collaboration between the $10^{99}$ key space and the dynamic window perturbation mechanism ensures both the security and processing efficiency of the communication system.
{"title":"Dual-Track Encryption Scheme for Ciphertext and Key Based on Dynamic Window Perturbation","authors":"Zhi Liu;Bo Liu;Jianxin Ren;Yaya Mao;Jianye Zhao;Xiumin Song;Shuaidong Chen;Tingting Sun;Haojun Liu;Chen Wang;Tao Chen","doi":"10.1109/LPT.2026.3653029","DOIUrl":"https://doi.org/10.1109/LPT.2026.3653029","url":null,"abstract":"This letter proposes a dual-track encryption scheme for ciphertext and key based on dynamic window perturbation, enabling highly secure information transmission in both the key and ciphertext dimensions. For key encryption, a modular exponentiation iteration algorithm is used to process the chaotic initial value key, which not only reduces the risk of key leakage but also expands the key space to <inline-formula> <tex-math>$10^{99}$ </tex-math></inline-formula>. For ciphertext encryption, a three-dimensional Lorenz chaotic map is used to generate decision factors. Symbols are grouped according to dynamic window sizes, and each group is perturbed and encrypted based on the decision factors. The core advantage of the scheme lies in its symbol-level dynamic grouping encryption mechanism. Unlike traditional bit-level encryption, this scheme avoids the overhead of encrypting each symbol individually by applying dynamic window perturbation to symbol groups, reducing time costs by approximately 50% and more than doubling efficiency. In the 2 kilometer seven-core fiber experiment, the scheme achieved an encrypted signal transmission rate of 110.74 Gb/s, with all fiber cores meeting the hard-decision forward error correction (FEC) bit error rate (BER) threshold of <inline-formula> <tex-math>$3.8{,}times{,}10^{-3}$ </tex-math></inline-formula>. Experimental results demonstrate that even in cases of partial key leakage or key misalignment at an unauthorized receiver, the collaboration between the <inline-formula> <tex-math>$10^{99}$ </tex-math></inline-formula> key space and the dynamic window perturbation mechanism ensures both the security and processing efficiency of the communication system.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 8","pages":"551-554"},"PeriodicalIF":2.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/LPT.2026.3653052
Chunyu Deng;Zheng Wu;Wanghua Zhu;Kun Yu
The optical power splitter is one of the crucial components of photonics integrated circuits. In this letter, we propose and demonstrate a broadband, compact and polarization-insensitive Y-junction power splitter based on the lithium niobate-on-insulator (LNOI) platform. This device employs an adiabatic coupling structure to achieve a 1:1 power distribution for both TE polarization and TM polarization. Experimental results show that in the wavelength of 1506-1615 nm, the insertion loss of this device is less than 0.7 dB and 0.5 dB for the TE${}_{mathbf {0}}$ and TM${}_{mathbf {0}}$ modes, respectively. Meanwhile, the polarization dependence loss is less than ±0.5dB. The proposed device can be applied to future high-density photonic integrated links.
{"title":"Polarization-Insensitive Y-Junction Power Splitter on Lithium Niobate-on-Insulator Platform","authors":"Chunyu Deng;Zheng Wu;Wanghua Zhu;Kun Yu","doi":"10.1109/LPT.2026.3653052","DOIUrl":"https://doi.org/10.1109/LPT.2026.3653052","url":null,"abstract":"The optical power splitter is one of the crucial components of photonics integrated circuits. In this letter, we propose and demonstrate a broadband, compact and polarization-insensitive Y-junction power splitter based on the lithium niobate-on-insulator (LNOI) platform. This device employs an adiabatic coupling structure to achieve a 1:1 power distribution for both TE polarization and TM polarization. Experimental results show that in the wavelength of 1506-1615 nm, the insertion loss of this device is less than 0.7 dB and 0.5 dB for the TE<inline-formula> <tex-math>${}_{mathbf {0}}$ </tex-math></inline-formula> and TM<inline-formula> <tex-math>${}_{mathbf {0}}$ </tex-math></inline-formula> modes, respectively. Meanwhile, the polarization dependence loss is less than ±0.5dB. The proposed device can be applied to future high-density photonic integrated links.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 8","pages":"519-522"},"PeriodicalIF":2.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/LPT.2026.3652043
Erfan Seifi;Peter LoPresti
This work presents a reinforcement learning (RL) approach for optimizing beam intensity in free-space optical communication (FSOC) links under thermal turbulence. A Twin Delayed Deep Deterministic Policy Gradient (TD3) agent controls Zernike phase parameters on a high-resolution spatial light modulator (SLM) to maximize received power. Experiments at 72°F, 240°F, and 280°F demonstrate consistent convergence and robust performance across varying turbulence levels, with convergence achieved in under 2.7 minutes and average power gains of 2–2.7 dB relative to a flat phase. The method is designed for next-generation low Earth orbit (LEO) optical links, where it can be applied to compact ground station terminals or feeder links to provide real-time adaptive phase correction and maintain stable communication under dynamic channel conditions.
{"title":"Beam Power Optimization in FSO Links Using Reinforcement Learning and SLM Control","authors":"Erfan Seifi;Peter LoPresti","doi":"10.1109/LPT.2026.3652043","DOIUrl":"https://doi.org/10.1109/LPT.2026.3652043","url":null,"abstract":"This work presents a reinforcement learning (RL) approach for optimizing beam intensity in free-space optical communication (FSOC) links under thermal turbulence. A Twin Delayed Deep Deterministic Policy Gradient (TD3) agent controls Zernike phase parameters on a high-resolution spatial light modulator (SLM) to maximize received power. Experiments at 72°F, 240°F, and 280°F demonstrate consistent convergence and robust performance across varying turbulence levels, with convergence achieved in under 2.7 minutes and average power gains of 2–2.7 dB relative to a flat phase. The method is designed for next-generation low Earth orbit (LEO) optical links, where it can be applied to compact ground station terminals or feeder links to provide real-time adaptive phase correction and maintain stable communication under dynamic channel conditions.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 7","pages":"491-494"},"PeriodicalIF":2.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this letter, a method of mixed contaminants identification based on 3D fluorescent spectroscopy with a novel generative model is proposed. To comprehensively characterize the 3D fluorescent spectra of contaminants, local and global features can be respectively extracted to represent the fluorescent peaks of substances and the overall trend of 3D fluorescent spectroscopy. Local features involving substance properties can be beneficial for improving authenticity, whereas global features can increase diversity as auxiliary information. For that, a Text-to-EEM (TTE) generative model is presented with convolution and retentive self-attention mechanisms to capture local and global features, respectively. In addition, spectral data can be generated from textual descriptions using text generation modules. Experiments using CNN identification network show that the maximum accuracy of samples generated by the TTE model was 67% for all correct and 20% for partially correct, better than GAN, WGAN, and WAE.
{"title":"Mixed Contaminants Identification Based on 3D Fluorescent Spectroscopy With TTE Model","authors":"Yingtian Hu;Xi Cui;Weidang Lu;Qiang Zheng;Dongdong Zhao","doi":"10.1109/LPT.2026.3651744","DOIUrl":"https://doi.org/10.1109/LPT.2026.3651744","url":null,"abstract":"In this letter, a method of mixed contaminants identification based on 3D fluorescent spectroscopy with a novel generative model is proposed. To comprehensively characterize the 3D fluorescent spectra of contaminants, local and global features can be respectively extracted to represent the fluorescent peaks of substances and the overall trend of 3D fluorescent spectroscopy. Local features involving substance properties can be beneficial for improving authenticity, whereas global features can increase diversity as auxiliary information. For that, a Text-to-EEM (TTE) generative model is presented with convolution and retentive self-attention mechanisms to capture local and global features, respectively. In addition, spectral data can be generated from textual descriptions using text generation modules. Experiments using CNN identification network show that the maximum accuracy of samples generated by the TTE model was 67% for all correct and 20% for partially correct, better than GAN, WGAN, and WAE.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 8","pages":"503-506"},"PeriodicalIF":2.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146001855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Titanium dioxide (TiO2) has garnered significant attention in integrated photonics due to its unique negative thermo-optic coefficient (TOC), a property essential for developing athermal devices and efficient thermo-optic switches on flexible platforms. In this paper, we compare sol-gel and magnetron-sputtered TiO2 waveguides, highlighting the dependence of their propagation loss and TOC on the deposition method. Sol-gel amorphous TiO2 waveguides exhibit propagation loss of 4.64 dB/cm at 1296.42 nm and TOC of $-2.58times 10 ^{mathbf {-5}}$ K${}^{mathbf {-1}}$ , while sputtered amorphous TiO2 waveguides show similar propagation loss (4.32 dB/cm at 1304.20 nm) but a three times larger TOC ($- 7.98times 10 ^{mathbf {-5}}$ K${}^{mathbf {-1}}$ ), which is attributed to their higher density and lower porosity. These results provide new insights for the development of waveguide-integrated high-performance thermo-optic devices and are expected to accelerate the advancement of next-generation photonic integrated circuits.
二氧化钛（TiO2）由于其独特的负热光系数（TOC）而在集成光子学中引起了极大的关注，这是在柔性平台上开发非热器件和高效热光开关所必需的特性。在本文中，我们比较了溶胶-凝胶和磁控溅射TiO2波导，强调了它们的传播损耗和TOC与沉积方法的关系。溶胶-凝胶型非晶TiO2波导在1296.42 nm处的传输损耗为4.64 dB/cm， TOC为$-2.58乘以10 ^{mathbf {-5}}$ K ${}}$ mathbf{-1}}$，而溅射型非晶TiO2波导在1304.20 nm处的传输损耗为4.32 dB/cm，但TOC为$- 7.98乘以10 ^{mathbf {-5}}$ K ${}}^{mathbf{-1}}$，这是由于其密度更高，孔隙率更低。这些结果为波导集成高性能热光器件的发展提供了新的见解，并有望加速下一代光子集成电路的发展。
{"title":"Enhanced Negative Thermo-Optic Coefficient in Sputtered Versus Sol-Gel TiO2 Waveguides","authors":"Yiheng Tang;Zequn Chen;Yingchun Wu;Maoliang Wei;Hui Ma;Ji Huang;Yuting Ye;Chunlei Sun;Zongxi Li;Xiaojing Li;Sishuo Zou;Hongtao Lin;Ke Si;Wei Gong;Lan Li","doi":"10.1109/LPT.2026.3652242","DOIUrl":"https://doi.org/10.1109/LPT.2026.3652242","url":null,"abstract":"Titanium dioxide (TiO2) has garnered significant attention in integrated photonics due to its unique negative thermo-optic coefficient (TOC), a property essential for developing athermal devices and efficient thermo-optic switches on flexible platforms. In this paper, we compare sol-gel and magnetron-sputtered TiO2 waveguides, highlighting the dependence of their propagation loss and TOC on the deposition method. Sol-gel amorphous TiO2 waveguides exhibit propagation loss of 4.64 dB/cm at 1296.42 nm and TOC of <inline-formula> <tex-math>$-2.58times 10 ^{mathbf {-5}}$ </tex-math></inline-formula> K<inline-formula> <tex-math>${}^{mathbf {-1}}$ </tex-math></inline-formula>, while sputtered amorphous TiO2 waveguides show similar propagation loss (4.32 dB/cm at 1304.20 nm) but a three times larger TOC (<inline-formula> <tex-math>$- 7.98times 10 ^{mathbf {-5}}$ </tex-math></inline-formula> K<inline-formula> <tex-math>${}^{mathbf {-1}}$ </tex-math></inline-formula>), which is attributed to their higher density and lower porosity. These results provide new insights for the development of waveguide-integrated high-performance thermo-optic devices and are expected to accelerate the advancement of next-generation photonic integrated circuits.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 8","pages":"515-518"},"PeriodicalIF":2.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146001856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/LPT.2026.3651593
Xiaoyang Li;Jingming Liu;Liuchen Lyu;Jinhui Cui;Vladimir R. Tuz;Yiwei Ma;Yongjun Liu;Tao Geng
In this work, an omnidirectional bending sensor based on dual Fabry-Perot interferometers (DFPIs) is designed and experimentally demonstrated. By eccentrically embedding a thin-diameter fiber (TDF) between two segments of seven-core fiber (SCF), DFPIs are formed and their spectrums are strongly correlated with the bending direction and curvature. A multi-scale convolutional and transformer neural network (MSCTnet) based on a hybrid loss function is employed to model the relationship between the bending state and the spectrum of DFPIs. Compared with other combinations of sensor structures and deep learning methods, the proposed DFPIs integrated with MSCTnet achieves higher prediction accuracy for bending states while requiring fewer training iterations. Experimental results demonstrate that the DFPIs achieve a curvature prediction accuracy of 99.53% with a mean absolute error (MAE) of 0.085 m−1. The azimuth angle prediction accuracy is 99.92%, with an MAE of 1.39°.
{"title":"Deep-Learning-Assisted Vector Bending Sensor Based on Dual-FPI Structure","authors":"Xiaoyang Li;Jingming Liu;Liuchen Lyu;Jinhui Cui;Vladimir R. Tuz;Yiwei Ma;Yongjun Liu;Tao Geng","doi":"10.1109/LPT.2026.3651593","DOIUrl":"https://doi.org/10.1109/LPT.2026.3651593","url":null,"abstract":"In this work, an omnidirectional bending sensor based on dual Fabry-Perot interferometers (DFPIs) is designed and experimentally demonstrated. By eccentrically embedding a thin-diameter fiber (TDF) between two segments of seven-core fiber (SCF), DFPIs are formed and their spectrums are strongly correlated with the bending direction and curvature. A multi-scale convolutional and transformer neural network (MSCTnet) based on a hybrid loss function is employed to model the relationship between the bending state and the spectrum of DFPIs. Compared with other combinations of sensor structures and deep learning methods, the proposed DFPIs integrated with MSCTnet achieves higher prediction accuracy for bending states while requiring fewer training iterations. Experimental results demonstrate that the DFPIs achieve a curvature prediction accuracy of 99.53% with a mean absolute error (MAE) of 0.085 m−1. The azimuth angle prediction accuracy is 99.92%, with an MAE of 1.39°.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 8","pages":"507-510"},"PeriodicalIF":2.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146001857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/LPT.2026.3652977
Ge Li;Jiameng Dong;Song Yu;Shangsu Ding
Laser offset frequency locking systems are essential for achieving high stability and precision in applications such as optical communications and continuous-variable quantum key distribution (CV-QKD). Conventional approaches typically rely on direct frequency measurement to determine the offset between the laser frequency and a target frequency, followed by feedback control to stabilize the output. However, the performance of such systems is often limited by the precision of the frequency measurement. In this work, we propose an offset frequency locking technique based on digital frequency division and time-interval measurement. The core of the technique is low-jitter frequency division combined with high-resolution time-interval measurement to extract the offset frequency deviation. It employs a field-programmable gate array (FPGA) to perform digital frequency division, incorporates a D flip-flop to reduce frequency-division jitter, and uses a high-precision time-to-digital converter (TDC) for time-interval detection. Experimental results show that the proposed system stabilizes the laser offset frequency to a peak-to-peak value of 288 kHz and a jitter of 46 kHz, corresponding to reductions of 64% and 49%, respectively, compared with commercial instruments. These results demonstrate the potential of the method for high-precision applications.
{"title":"Laser Offset Frequency Locking Based on Digital Frequency Division and Time-Interval Detection","authors":"Ge Li;Jiameng Dong;Song Yu;Shangsu Ding","doi":"10.1109/LPT.2026.3652977","DOIUrl":"https://doi.org/10.1109/LPT.2026.3652977","url":null,"abstract":"Laser offset frequency locking systems are essential for achieving high stability and precision in applications such as optical communications and continuous-variable quantum key distribution (CV-QKD). Conventional approaches typically rely on direct frequency measurement to determine the offset between the laser frequency and a target frequency, followed by feedback control to stabilize the output. However, the performance of such systems is often limited by the precision of the frequency measurement. In this work, we propose an offset frequency locking technique based on digital frequency division and time-interval measurement. The core of the technique is low-jitter frequency division combined with high-resolution time-interval measurement to extract the offset frequency deviation. It employs a field-programmable gate array (FPGA) to perform digital frequency division, incorporates a D flip-flop to reduce frequency-division jitter, and uses a high-precision time-to-digital converter (TDC) for time-interval detection. Experimental results show that the proposed system stabilizes the laser offset frequency to a peak-to-peak value of 288 kHz and a jitter of 46 kHz, corresponding to reductions of 64% and 49%, respectively, compared with commercial instruments. These results demonstrate the potential of the method for high-precision applications.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 8","pages":"523-526"},"PeriodicalIF":2.5,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Commercially available liquid crystal on silicon (LCoS) spatial light modulators (SLMs) typically consist of a liquid crystal (LC) cell that controls the wavefront of polarized light along its slow axis. In this work, we introduce a dual slow-axis (DSA) SLM based on LCoS technology. This configuration enables independent control of the phase delay for both orthogonally polarized components of light. This device is referred to as DSA SLM, since it contains two cascaded LC cells with their slow axes oriented perpendicular to each other. The proposed method’s functionality has been verified through experimental and simulation studies. The versatile functionality of DSA SLM can be useful for various applications where polarization-dependent light modulation is needed.
{"title":"Generation of Cylindrical-Vector Beams Using a Dual Slow-Axis Liquid Crystal Spatial Light Modulator","authors":"Kushal Kumar Tripathi;Gunjan Sinha;Awakash Dixit;Praveen Kumar","doi":"10.1109/LPT.2026.3651500","DOIUrl":"https://doi.org/10.1109/LPT.2026.3651500","url":null,"abstract":"Commercially available liquid crystal on silicon (LCoS) spatial light modulators (SLMs) typically consist of a liquid crystal (LC) cell that controls the wavefront of polarized light along its slow axis. In this work, we introduce a dual slow-axis (DSA) SLM based on LCoS technology. This configuration enables independent control of the phase delay for both orthogonally polarized components of light. This device is referred to as DSA SLM, since it contains two cascaded LC cells with their slow axes oriented perpendicular to each other. The proposed method’s functionality has been verified through experimental and simulation studies. The versatile functionality of DSA SLM can be useful for various applications where polarization-dependent light modulation is needed.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 8","pages":"539-542"},"PeriodicalIF":2.5,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-05DOI: 10.1109/LPT.2026.3650866
Simon Michael Laube;Christoph Gasser;Horst Zimmermann
In this letter, we report experimental results of two ultra-sensitive direct detection optoelectronic integrated circuits (OEICs), realized in 180 nm high-voltage CMOS. The receivers are comprised of a dot-cathode avalanche photodiode (APD), common-source integrate-and-dump front-end, and correlated double sampling (CDS) equalizer. At 200 Mb/s (100 Mb/s), bit error probability (BER) of $10^{-6}$ , 642 nm wavelength, and 50% return-to-zero on-off keying modulation the best measured sensitivity is −51.8 dBm (−56.4 dBm), equal to a distance of just 12.1 dB (10.5 dB) to the quantum limit. At 100 Mb/s and a BER of 2 $cdot $ $10^{-3}$ , the gap to the quantum limit of 10 dB is achieved.
{"title":"Dot-Cathode APD Receiver OEICs Achieving Sensitivity Gaps to the Quantum Limit Down to 10 dB","authors":"Simon Michael Laube;Christoph Gasser;Horst Zimmermann","doi":"10.1109/LPT.2026.3650866","DOIUrl":"https://doi.org/10.1109/LPT.2026.3650866","url":null,"abstract":"In this letter, we report experimental results of two ultra-sensitive direct detection optoelectronic integrated circuits (OEICs), realized in 180 nm high-voltage CMOS. The receivers are comprised of a dot-cathode avalanche photodiode (APD), common-source integrate-and-dump front-end, and correlated double sampling (CDS) equalizer. At 200 Mb/s (100 Mb/s), bit error probability (BER) of <inline-formula> <tex-math>$10^{-6}$ </tex-math></inline-formula>, 642 nm wavelength, and 50% return-to-zero on-off keying modulation the best measured sensitivity is −51.8 dBm (−56.4 dBm), equal to a distance of just 12.1 dB (10.5 dB) to the quantum limit. At 100 Mb/s and a BER of 2 <inline-formula> <tex-math>$cdot $ </tex-math></inline-formula> <inline-formula> <tex-math>$10^{-3}$ </tex-math></inline-formula>, the gap to the quantum limit of 10 dB is achieved.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 8","pages":"547-550"},"PeriodicalIF":2.5,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11328804","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2026-01-05DOI: 10.1109/LPT.2026.3650783
Siyu Bai;Yibin Li;Zehua Xu;Qian Li;H. Y. Fu
We propose and experimentally demonstrate a distribution-adaptive quantization scheme, termed the fuzzy-minimized mapping (FMM) quantizer, for high-speed ACO-OFDM VLC transmitters employing low-resolution DACs. The FMM quantizer combines fuzzy c-means (FCM) clustering with minimum mean-square error (MMSE) refinement to adaptively optimize quantization under non-Gaussian signal distributions. Experimental results over a 1 m free-space VLC link using a red VCSEL transmitter show that FMM outperforms conventional Lloyd–Max and round-off (RO) quantizers, achieving a BER of ($2.3times {10}^{-3}$ ) for 16-QAM at 0.75 GBaud with 2-bit resolution and supporting 64-QAM at 0.625 GBaud (3-bit) with a BER of ($2.8times {10}^{-3}$ ). Constellation diagrams further illustrate these gains, confirming the FMM quantizer’s practical effectiveness for Gbps-level VLC with low-resolution transmitter hardware.
{"title":"Distribution-Adaptive Quantization for Ultra-Low-Resolution Transmitter in IM/DD VLC Links","authors":"Siyu Bai;Yibin Li;Zehua Xu;Qian Li;H. Y. Fu","doi":"10.1109/LPT.2026.3650783","DOIUrl":"https://doi.org/10.1109/LPT.2026.3650783","url":null,"abstract":"We propose and experimentally demonstrate a distribution-adaptive quantization scheme, termed the fuzzy-minimized mapping (FMM) quantizer, for high-speed ACO-OFDM VLC transmitters employing low-resolution DACs. The FMM quantizer combines fuzzy c-means (FCM) clustering with minimum mean-square error (MMSE) refinement to adaptively optimize quantization under non-Gaussian signal distributions. Experimental results over a 1 m free-space VLC link using a red VCSEL transmitter show that FMM outperforms conventional Lloyd–Max and round-off (RO) quantizers, achieving a BER of (<inline-formula> <tex-math>$2.3times {10}^{-3}$ </tex-math></inline-formula>) for 16-QAM at 0.75 GBaud with 2-bit resolution and supporting 64-QAM at 0.625 GBaud (3-bit) with a BER of (<inline-formula> <tex-math>$2.8times {10}^{-3}$ </tex-math></inline-formula>). Constellation diagrams further illustrate these gains, confirming the FMM quantizer’s practical effectiveness for Gbps-level VLC with low-resolution transmitter hardware.","PeriodicalId":13065,"journal":{"name":"IEEE Photonics Technology Letters","volume":"38 9","pages":"563-566"},"PeriodicalIF":2.5,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146139117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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