Pub Date : 2025-02-14DOI: 10.1109/JPHOT.2025.3542540
Michal Jelínek;Milan Frank;Václav Kubeček;Ondřej Novák;Jaroslav Huynh;Martin Cimrman;Michal Chyla;Martin Smrž;Tomáš Mocek
Comparative study of nonlinear crystals for picosecond difference frequency generation in mid-IR is presented. Nonlinear crystals of AgGaS2, BaGa4 Se7, LiGaSe2, and LiGaS2 were studied. In order to investigate the dependence of efficiency on the crystal length, three sets of crystals with lengths of 2, 4, or 8 mm were tested. The developed tunable DFG system was driven by the 1.03 µm, 1.8 ps, Yb:YAG thin-disk laser system operated at the repetition rate of 10 or 100 Hz. As the best result, picosecond mid-IR pulses at a wavelength of $sim$7 µm with the energy up to 130 µJ corresponding to the peak power of $sim$72 MW were generated using the 8 mm long LiGaS2 crystal. Using the BaGa4 Se7 crystal, DFG tunability in the wavelength range from 6 up to 13 µm was achieved.
{"title":"70 MW-Level Picosecond Mid-Infrared Radiation Generation by Difference Frequency Generation in AgGaS2, BaGa4Se7, LiGaSe2, and LiGaS2","authors":"Michal Jelínek;Milan Frank;Václav Kubeček;Ondřej Novák;Jaroslav Huynh;Martin Cimrman;Michal Chyla;Martin Smrž;Tomáš Mocek","doi":"10.1109/JPHOT.2025.3542540","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3542540","url":null,"abstract":"Comparative study of nonlinear crystals for picosecond difference frequency generation in mid-IR is presented. Nonlinear crystals of AgGaS<sub>2</sub>, BaGa<sub>4</sub> Se<sub>7</sub>, LiGaSe<sub>2</sub>, and LiGaS<sub>2</sub> were studied. In order to investigate the dependence of efficiency on the crystal length, three sets of crystals with lengths of 2, 4, or 8 mm were tested. The developed tunable DFG system was driven by the 1.03 µm, 1.8 ps, Yb:YAG thin-disk laser system operated at the repetition rate of 10 or 100 Hz. As the best result, picosecond mid-IR pulses at a wavelength of <inline-formula><tex-math>$sim$</tex-math></inline-formula>7 µm with the energy up to 130 µJ corresponding to the peak power of <inline-formula><tex-math>$sim$</tex-math></inline-formula>72 MW were generated using the 8 mm long LiGaS<sub>2</sub> crystal. Using the BaGa<sub>4</sub> Se<sub>7</sub> crystal, DFG tunability in the wavelength range from 6 up to 13 µm was achieved.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-7"},"PeriodicalIF":2.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10890961","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553283","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 : 2025-02-14DOI: 10.1109/JPHOT.2025.3542598
Jos E. Boschker;David Feise;Uwe Spengler;Peter Ressel;Katrin Paschke;Andrea Knigge
High power, compact, red edge-emitting lasers based on GaInP quantum wells are desirable for applications such as laser display technologies or two-photon upconversion. Here, we investigate the influence of passivation methods on the performance of 635 nm ridge waveguide lasers. We demonstrate that vacuum cleaving results in a higher facet stability compared to hydrogen cleaning, resulting in a reliable output power for 7.5 μm wide emitters of 200 mW for one week and 160 mW for 2000 hours. Moreover, our investigation shows that it is essential to consider the thermal budget of passivation methods for the optimization of the laser performance of phosphide-based lasers.
{"title":"Influence of the Passivation Method on the Performance of 635 nm Ridge Waveguide Lasers","authors":"Jos E. Boschker;David Feise;Uwe Spengler;Peter Ressel;Katrin Paschke;Andrea Knigge","doi":"10.1109/JPHOT.2025.3542598","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3542598","url":null,"abstract":"High power, compact, red edge-emitting lasers based on GaInP quantum wells are desirable for applications such as laser display technologies or two-photon upconversion. Here, we investigate the influence of passivation methods on the performance of 635 nm ridge waveguide lasers. We demonstrate that vacuum cleaving results in a higher facet stability compared to hydrogen cleaning, resulting in a reliable output power for 7.5 μm wide emitters of 200 mW for one week and 160 mW for 2000 hours. Moreover, our investigation shows that it is essential to consider the thermal budget of passivation methods for the optimization of the laser performance of phosphide-based lasers.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-4"},"PeriodicalIF":2.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10890986","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143535475","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 : 2025-02-14DOI: 10.1109/JPHOT.2025.3542592
Anadi Agnihotri;Pradeep Kumar Krishnamurthy
We demonstrate an all-fiber broadband photon pair source based on four wave mixing (FWM) process in dispersion flattened highly non-linear fiber (DF-HNLF). The fiber exhibits a zero dispersion slope near 1550 nm, allowing phase-matched FWM over entire S, C, and L bands and thus efficient generation of signal and idler photons. A comparative theoretical study between conventional dispersion-shifted fiber (DSF) and DF-HNLF highlights the spectral range differences in the generation of photon pairs. We measure coincidence counts at three different sets of wavelengths. To study the effects of Raman scattering, which acts as noise source in these types of fibers, we calculate the correlation $g^{(2)}(tau)$ at different pump powers. We use stimulated emission tomography to characterize the generation of photon pairs across the S, C, and L bands. We show that DF-HNLF is an ideal medium for generating correlated photons over a broad spectral range ($>!!100,text{nm}$), making it suitable for frequency-multiplexed quantum communication systems. We estimate the photon pair generation efficiency to be 0.05 $text{mW}^{-2}/text{pulse}$.
我们展示了一种全光纤宽带光子对源，它基于色散扁平高非线性光纤（DF-HNLF）中的四波混合（FWM）过程。这种光纤在 1550 nm 附近的色散斜率为零，因此可以在整个 S、C 和 L 波段实现相位匹配的 FWM，从而高效地产生信号光子和惰性光子。通过对传统色散位移光纤（DSF）和 DF-HNLF 进行比较理论研究，我们发现了光子对产生的光谱范围差异。我们测量了三组不同波长下的重合计数。为了研究拉曼散射的影响，我们计算了不同泵浦功率下的相关性 $g^{(2)}(tau)$。我们使用受激发射断层扫描来描述跨 S、C 和 L 波段的光子对的产生。我们的研究表明，DF-HNLF是在宽光谱范围（$>!!100,text{nm}$）内产生相关光子的理想介质，使其适用于频率多路复用量子通信系统。我们估计光子对的生成效率为 0.05 $text{mW}^{-2}/text{pulse}$ 。
{"title":"All-Fiber Broadband Photon Pair Generation in Dispersion Flattened Highly Non-Linear Fibers","authors":"Anadi Agnihotri;Pradeep Kumar Krishnamurthy","doi":"10.1109/JPHOT.2025.3542592","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3542592","url":null,"abstract":"We demonstrate an all-fiber broadband photon pair source based on four wave mixing (FWM) process in dispersion flattened highly non-linear fiber (DF-HNLF). The fiber exhibits a zero dispersion slope near 1550 nm, allowing phase-matched FWM over entire S, C, and L bands and thus efficient generation of signal and idler photons. A comparative theoretical study between conventional dispersion-shifted fiber (DSF) and DF-HNLF highlights the spectral range differences in the generation of photon pairs. We measure coincidence counts at three different sets of wavelengths. To study the effects of Raman scattering, which acts as noise source in these types of fibers, we calculate the correlation <inline-formula><tex-math>$g^{(2)}(tau)$</tex-math></inline-formula> at different pump powers. We use stimulated emission tomography to characterize the generation of photon pairs across the S, C, and L bands. We show that DF-HNLF is an ideal medium for generating correlated photons over a broad spectral range (<inline-formula><tex-math>$>!!100,text{nm}$</tex-math></inline-formula>), making it suitable for frequency-multiplexed quantum communication systems. We estimate the photon pair generation efficiency to be 0.05 <inline-formula><tex-math>$text{mW}^{-2}/text{pulse}$</tex-math></inline-formula>.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-7"},"PeriodicalIF":2.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10890974","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521431","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 : 2025-02-13DOI: 10.1109/JPHOT.2025.3541323
J. Taylor-Mew;L. Li;T. Blain;C. H. Tan;J. S. Ng
Near-infrared Single Photon Avalanche Diodes (SPADs) are the dominant, practical single photon detectors for quantum applications and low-level optical sensing. Although some infrared SPADs can operate at room temperature, thermoelectric coolers are still essential, increasing complexity (operation and device packaging) and power consumption. Passively-cooled SPADs could be realized by avalanche materials exhibiting better temperature stability. A promising candidate is the InGaAs/AlGaAsSb SPAD, because the AlGaAsSb multiplier is highly stable with temperature. In this work, we report single photon detection performance of InGaAs/AlGaAsSb SPADs at room temperature and 1550 nm wavelength using multiple devices for each type of measurements. With 0.1 photons per pulse and 15 μm diameter devices, the maximum SPDE was 14% at DCR of 30 Mc.s−1, respectively. The best NEP value is around an order of magnitude higher than InGaAs/InP SPADs, but are comparable to InGaAs/InAlAs SPADs. Within the relevant overbias range and repetition rate up to 1 MHz, the DCR was unaffected by afterpulsing. Timing jitters were as low as 150 ps, matching InGaAs/InP SPADs. The results of this work are much more competitive than the previous report of InGaAs/AlGaAsSb SPAD, which required cooling to 200 K to detect single photons. Further research could help InGaAs/AlGaAsSb SPADs progressing towards passively-cooled single photon detectors for room temperature operation.
{"title":"Room Temperature InGaAs/AlGaAsSb Single Photon Avalanche Diode","authors":"J. Taylor-Mew;L. Li;T. Blain;C. H. Tan;J. S. Ng","doi":"10.1109/JPHOT.2025.3541323","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3541323","url":null,"abstract":"Near-infrared Single Photon Avalanche Diodes (SPADs) are the dominant, practical single photon detectors for quantum applications and low-level optical sensing. Although some infrared SPADs can operate at room temperature, thermoelectric coolers are still essential, increasing complexity (operation and device packaging) and power consumption. Passively-cooled SPADs could be realized by avalanche materials exhibiting better temperature stability. A promising candidate is the InGaAs/AlGaAsSb SPAD, because the AlGaAsSb multiplier is highly stable with temperature. In this work, we report single photon detection performance of InGaAs/AlGaAsSb SPADs at room temperature and 1550 nm wavelength using multiple devices for each type of measurements. With 0.1 photons per pulse and 15 μm diameter devices, the maximum SPDE was 14% at DCR of 30 Mc.s<sup>−1</sup>, respectively. The best NEP value is around an order of magnitude higher than InGaAs/InP SPADs, but are comparable to InGaAs/InAlAs SPADs. Within the relevant overbias range and repetition rate up to 1 MHz, the DCR was unaffected by afterpulsing. Timing jitters were as low as 150 ps, matching InGaAs/InP SPADs. The results of this work are much more competitive than the previous report of InGaAs/AlGaAsSb SPAD, which required cooling to 200 K to detect single photons. Further research could help InGaAs/AlGaAsSb SPADs progressing towards passively-cooled single photon detectors for room temperature operation.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-6"},"PeriodicalIF":2.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10884001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512877","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 : 2025-02-13DOI: 10.1109/JPHOT.2025.3532991
Lu Chen;Lifang Feng;Jianping Wang;Tianyi Zhang;Haijun Zhang;Zhuo Xue
Visible light positioning (VLP) is one of the effective solutions for low-cost and high-precision indoor positioning in the emerging wireless communication ecosystem, particularly in the context of 6G networks, due to its advantages of low latency, high data transmission rates, and immunity from radio frequency induced electromagnetic interference. However, severe performance limitations, including line-of-sight dependency, signal attenuation caused by obstacles, and restricted coverage, present a major challenge for the development of VLP. This article constructs an LED array-based hybrid indoor positioning system. An innovative LED array beacon is developed to simultaneously transmit coordinate and graphical information. A hybrid receiving structure, comprising an image sensor (IS) and a photodetector (PD), is constructed along with a dedicated hybrid positioning algorithm. This algorithm leverages image processing techniques to track the target trajectory, converts light intensity to identify the identification of LED, which finally resolves the target's precise world coordinates. The system's performance was validated through three experimental trials. The results demonstrate that the proposed beacon effectively covers the entire positioning area, achieving an average positioning error of 8.32 cm and a maximum positioning distance of 6.8 m. These results suggest that the proposed system provides a robust and efficient solution for precise indoor positioning applications in next-generation wireless communication networks.
{"title":"Hybrid Indoor Positioning System Based on LED Array","authors":"Lu Chen;Lifang Feng;Jianping Wang;Tianyi Zhang;Haijun Zhang;Zhuo Xue","doi":"10.1109/JPHOT.2025.3532991","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3532991","url":null,"abstract":"Visible light positioning (VLP) is one of the effective solutions for low-cost and high-precision indoor positioning in the emerging wireless communication ecosystem, particularly in the context of 6G networks, due to its advantages of low latency, high data transmission rates, and immunity from radio frequency induced electromagnetic interference. However, severe performance limitations, including line-of-sight dependency, signal attenuation caused by obstacles, and restricted coverage, present a major challenge for the development of VLP. This article constructs an LED array-based hybrid indoor positioning system. An innovative LED array beacon is developed to simultaneously transmit coordinate and graphical information. A hybrid receiving structure, comprising an image sensor (IS) and a photodetector (PD), is constructed along with a dedicated hybrid positioning algorithm. This algorithm leverages image processing techniques to track the target trajectory, converts light intensity to identify the identification of LED, which finally resolves the target's precise world coordinates. The system's performance was validated through three experimental trials. The results demonstrate that the proposed beacon effectively covers the entire positioning area, achieving an average positioning error of 8.32 cm and a maximum positioning distance of 6.8 m. These results suggest that the proposed system provides a robust and efficient solution for precise indoor positioning applications in next-generation wireless communication networks.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-11"},"PeriodicalIF":2.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10886945","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455329","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 : 2025-02-13DOI: 10.1109/JPHOT.2025.3541933
Georgia Himona;Yannis Kominis
This study explores the dynamics of optically injected semiconductor lasers under current modulation by periodic pulse sequences of various characteristics, focusing on the generation and control of microwave frequency combs (MFCs). Using simplified one-dimensional models –Poincaré circle maps–, the system's response to Dirac-delta, rectangular, and Gaussian pulse trains is analyzed. Modulation parameters such as amplitude, pulse width, and frequency detuning govern the emergence of frequency-locked states and chaotic oscillations, leading to distinct spectral outputs. A modular arithmetic relation between the frequencies of the modulation and the internal oscillation is shown to result in integer and fractional frequency division. The findings offer insights into tuning MFCs for applications in high-resolution measurement, microwave photonics, and data transmission.
{"title":"Modular Arithmetic of Microwave Frequency Combs Generated by a Modulated Photonic Oscillator","authors":"Georgia Himona;Yannis Kominis","doi":"10.1109/JPHOT.2025.3541933","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3541933","url":null,"abstract":"This study explores the dynamics of optically injected semiconductor lasers under current modulation by periodic pulse sequences of various characteristics, focusing on the generation and control of microwave frequency combs (MFCs). Using simplified one-dimensional models –Poincaré circle maps–, the system's response to Dirac-delta, rectangular, and Gaussian pulse trains is analyzed. Modulation parameters such as amplitude, pulse width, and frequency detuning govern the emergence of frequency-locked states and chaotic oscillations, leading to distinct spectral outputs. A modular arithmetic relation between the frequencies of the modulation and the internal oscillation is shown to result in integer and fractional frequency division. The findings offer insights into tuning MFCs for applications in high-resolution measurement, microwave photonics, and data transmission.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-9"},"PeriodicalIF":2.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10884871","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143535447","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 : 2025-02-12DOI: 10.1109/JPHOT.2025.3540839
Hongyu Li;Xinghan Li;Mengfan Cheng;Qi Yang;Ming Tang;Deming Liu;Lei Deng
A fast, accurate automatic bias control (ABC) scheme with low disturbance for optical IQ modulators is proposed by using the dither-vector-mapping monitoring (DVMM) technique. The proposed scheme solely necessitates vector length calculation via addition and subtraction operations and obviates the necessity of employing a direct digital synthesis (DDS) module, in contrast to conventional ABC schemes. By this means, the proposed scheme demonstrates reduced algorithmic complexity and a faster convergence rate, requiring only 0.3∼0.5 s to track and lock from a random bias point to a linear bias point, about 30 times faster than current commercial products. Moreover, unlike the commonly used single-tone dither signal (STDS), the PRBS-based dither signal in this scheme is broadband and has lower power spectral density and peak power at the same power level. Therefore, it not only induces lower nonlinear distortion in the transmitted signal but also has strong noise resistance, contributing to good control accuracy and robustness. The performance of DVMM-based ABC and STDS-based ABC is evaluated in 40/20 Gbaud 16/64 QAM coherent optical transmission systems, showing that DVMM can effectively reduce the bit error rate (BER) and has superior transmission performance.
{"title":"Fast, Accurate, and Low-Disturbance Automatic Bias Control for Coherent Optical Transmitter Using Dither Vector Mapping Monitoring","authors":"Hongyu Li;Xinghan Li;Mengfan Cheng;Qi Yang;Ming Tang;Deming Liu;Lei Deng","doi":"10.1109/JPHOT.2025.3540839","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3540839","url":null,"abstract":"A fast, accurate automatic bias control (ABC) scheme with low disturbance for optical IQ modulators is proposed by using the dither-vector-mapping monitoring (DVMM) technique. The proposed scheme solely necessitates vector length calculation via addition and subtraction operations and obviates the necessity of employing a direct digital synthesis (DDS) module, in contrast to conventional ABC schemes. By this means, the proposed scheme demonstrates reduced algorithmic complexity and a faster convergence rate, requiring only 0.3∼0.5 s to track and lock from a random bias point to a linear bias point, about 30 times faster than current commercial products. Moreover, unlike the commonly used single-tone dither signal (STDS), the PRBS-based dither signal in this scheme is broadband and has lower power spectral density and peak power at the same power level. Therefore, it not only induces lower nonlinear distortion in the transmitted signal but also has strong noise resistance, contributing to good control accuracy and robustness. The performance of DVMM-based ABC and STDS-based ABC is evaluated in 40/20 Gbaud 16/64 QAM coherent optical transmission systems, showing that DVMM can effectively reduce the bit error rate (BER) and has superior transmission performance.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-5"},"PeriodicalIF":2.1,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10882879","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518846","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 : 2025-02-06DOI: 10.1109/JPHOT.2025.3539420
Hannes F. Dreier;Ali Derakhshandeh;Andrej Harlakin;Peter A. Hoeher
A novel technique is proposed for estimating the angle-of-arrival (AOA) in free-space laser communication based on the shape of a laser beam spot on a flat surface. Two methods are introduced: one where ellipses are fitted to the intensity contour of the beam spot, and another where a least-squares fit of an AOA-dependent two-dimensional Gaussian distribution is applied to the intensity distribution. The effects of beam displacement, discretization, and noise on estimation performance are analyzed. The Cramér-Rao lower bound is derived and examined in relation to the true AOA. Both methods are verified through numerical simulations and experiments. For experimental validation, a novel beam sampling technique using a liquid-crystal display and a single photodiode is developed.
{"title":"Beam-Shape-Based Angle-of-Arrival Estimation in Free-Space Laser Communication","authors":"Hannes F. Dreier;Ali Derakhshandeh;Andrej Harlakin;Peter A. Hoeher","doi":"10.1109/JPHOT.2025.3539420","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3539420","url":null,"abstract":"A novel technique is proposed for estimating the angle-of-arrival (AOA) in free-space laser communication based on the shape of a laser beam spot on a flat surface. Two methods are introduced: one where ellipses are fitted to the intensity contour of the beam spot, and another where a least-squares fit of an AOA-dependent two-dimensional Gaussian distribution is applied to the intensity distribution. The effects of beam displacement, discretization, and noise on estimation performance are analyzed. The Cramér-Rao lower bound is derived and examined in relation to the true AOA. Both methods are verified through numerical simulations and experiments. For experimental validation, a novel beam sampling technique using a liquid-crystal display and a single photodiode is developed.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-16"},"PeriodicalIF":2.1,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10876596","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455320","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}
To address thermal effects in end-pumped solid-state lasers, this paper introduces a new motion concept called “quasi-rotating” and proposes a specialized method for evaluating the thermal focal length of dynamic gain medium, which proves valuable for resonator design. Using the finite element numerical analysis method, we analyze the changes of the temperature field distribution within the crystal and demonstrate the effectiveness of the “quasi-rotating” cooling system in thermal management. The results show that the “quasi-rotating” frequency and pump power have a more significant influence on the thermal lens effect than the cooling water temperature. Compared to previous studies, our new method accurately predicts the thermal focal length of the moving crystal and provides direct guidance for resonator design, as shown in this paper. These findings provide a theoretical foundation for the design and enhancement of high-power solid-state lasers. Moreover, the approach offers meaningful insights for the design of other non-traditional lasers with dynamic gain medium.
{"title":"Numerical Simulation of Thermal Lens Effect in Laser Diode End-Pumped Solid-State “Quasi-Rotating” Lasers","authors":"Minghai Wang;Zhuanglin Qian;Xuan Lv;Ying Wang;Peifeng Chen","doi":"10.1109/JPHOT.2025.3539517","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3539517","url":null,"abstract":"To address thermal effects in end-pumped solid-state lasers, this paper introduces a new motion concept called “quasi-rotating” and proposes a specialized method for evaluating the thermal focal length of dynamic gain medium, which proves valuable for resonator design. Using the finite element numerical analysis method, we analyze the changes of the temperature field distribution within the crystal and demonstrate the effectiveness of the “quasi-rotating” cooling system in thermal management. The results show that the “quasi-rotating” frequency and pump power have a more significant influence on the thermal lens effect than the cooling water temperature. Compared to previous studies, our new method accurately predicts the thermal focal length of the moving crystal and provides direct guidance for resonator design, as shown in this paper. These findings provide a theoretical foundation for the design and enhancement of high-power solid-state lasers. Moreover, the approach offers meaningful insights for the design of other non-traditional lasers with dynamic gain medium.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-9"},"PeriodicalIF":2.1,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10876626","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143496588","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}
In this paper, a novel strategy of employing microwave photonic (MWP) time-frequency limiter (TFL) for microwave photonic multiband radar is proposed to suppress the interference, achieving real-time response to the interference scenarios and high-resolution target detection. By mapping the echo signal into optical domain, the time-frequency characteristic is re-constructed through stimulated Brillouin scattering (SBS), realizing the selective suppression on high-power optical signal mapped by the interference. Based on this concept, a MWP TFL system based on the optical spectrum processing is constructed, and proof-of-concept experiments are demonstrated to verify the feasibility of the proposed strategy under different interference scenarios. Employing the proposed MWP TFL, the signal-to-noise ratio of the detection results, which is severely degraded by asynchronous interference, can be improved by 27.97 dB, and the suppression ratio on the false targets generated by the synchronous interference can reach 34.10 dB. The experimental results shows that the strategy can further enhance the survivability of multiband radar without compromising the range resolution for target detection. In addition, experiments are carried out to demonstrate the capability of the proposed strategy under different interference-to-signal ratios, showing a good adaptability to the complex interference scenarios.
{"title":"Multiband Radar Using Microwave Photonic Time-Frequency Limiter for Real-Time Detection in Interference Scenarios","authors":"Luhang Xing;Shangyuan Li;Xiaoxiao Xue;Xiaoping Zheng;Bingkun Zhou","doi":"10.1109/JPHOT.2025.3537684","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3537684","url":null,"abstract":"In this paper, a novel strategy of employing microwave photonic (MWP) time-frequency limiter (TFL) for microwave photonic multiband radar is proposed to suppress the interference, achieving real-time response to the interference scenarios and high-resolution target detection. By mapping the echo signal into optical domain, the time-frequency characteristic is re-constructed through stimulated Brillouin scattering (SBS), realizing the selective suppression on high-power optical signal mapped by the interference. Based on this concept, a MWP TFL system based on the optical spectrum processing is constructed, and proof-of-concept experiments are demonstrated to verify the feasibility of the proposed strategy under different interference scenarios. Employing the proposed MWP TFL, the signal-to-noise ratio of the detection results, which is severely degraded by asynchronous interference, can be improved by 27.97 dB, and the suppression ratio on the false targets generated by the synchronous interference can reach 34.10 dB. The experimental results shows that the strategy can further enhance the survivability of multiband radar without compromising the range resolution for target detection. In addition, experiments are carried out to demonstrate the capability of the proposed strategy under different interference-to-signal ratios, showing a good adaptability to the complex interference scenarios.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-8"},"PeriodicalIF":2.1,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10870138","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430457","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}
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