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Loss induced negative refraction and super-prism effect at highly absorptive interface
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作者 Jian Wu Tao Wang +4 位作者 tianyue hou Xuefen Kan Cheng Yin Pu Zhou Zhuangqi Cao 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第5期101-105,共5页
It is well-established that waves are inhomogeneous in a lossy isotropic medium, and the validation of the classical Snell's law is still questionable for light refraction at the dissipative and dispersive interfa... It is well-established that waves are inhomogeneous in a lossy isotropic medium, and the validation of the classical Snell's law is still questionable for light refraction at the dissipative and dispersive interface. With high absorption, direct experimental investigation is rather difficult due to the extremely short penetration depth; i.e., the skin depth. In this paper, a simple and unified description of this issue is proposed, which can be applied to both materials with anomalous dispersion and in the Drude region. The gradient ▽_k~ω is found to be incident angle θ_i-dependent, and the direction of the group velocity may deviate significantly from the phase velocity due to the loss induced permittivity structure. The physics behind the negative refraction effect is explained, and a novel loss induced super-prism effect is also predicted. 展开更多
关键词 Snell’s LAW Drude model ANOMALOUS dispersion LOSSY ISOTROPIC media
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First experimental demonstration of coherent beam combining of more than 100 beams 被引量:22
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作者 HONGXIANG CHANG QI CHANG +7 位作者 JIACHAO XI tianyue hou RONGTAO SU PENGFEI MA JIAN WUCAN LI MAN JIANG YANXING MA PU Zhou 《Photonics Research》 SCIE EI CAS CSCD 2020年第12期1943-1948,共6页
Coherent beam combining of 107 beams has been demonstrated for the first time to the best of our knowledge.When the system was in closed loop,the pattern in far-field was stable and the fringe contrast was>96%.The ... Coherent beam combining of 107 beams has been demonstrated for the first time to the best of our knowledge.When the system was in closed loop,the pattern in far-field was stable and the fringe contrast was>96%.The impact of the dynamic tilt error,the piston error,and power inconsistency was theoretically analyzed.Meanwhile,the distribution law of dynamic tilt error was estimated and the correlation of the tilt dithering of different axis was analyzed statistically.The ratio of power in the central lobe was^22.5%.The phase residue error in the closed loop was~λ∕22,which was evaluated by the root-mean-square error of the signal generated from the photoelectric detector. 展开更多
关键词 ERROR BEAM COHERENT
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Deep-learning-based phase control method for tiled aperture coherent beam combining systems 被引量:15
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作者 tianyue hou Yi An +8 位作者 Qi Chang Pengfei Ma Jun Li Dong Zhi Liangjin Huang Rongtao Su Jian Wu Yanxing Ma Pu Zhou 《High Power Laser Science and Engineering》 SCIE CAS CSCD 2019年第4期8-14,共7页
We incorporate deep learning(DL)into tiled aperture coherent beam combining(CBC)systems for the first time,to the best of our knowledge.By using a well-trained convolutional neural network DL model,which has been cons... We incorporate deep learning(DL)into tiled aperture coherent beam combining(CBC)systems for the first time,to the best of our knowledge.By using a well-trained convolutional neural network DL model,which has been constructed at a non-focal-plane to avoid the data collision problem,the relative phase of each beamlet could be accurately estimated,and then the phase error in the CBC system could be compensated directly by a servo phase control system.The feasibility and extensibility of the phase control method have been demonstrated by simulating the coherent combining of different hexagonal arrays.This DL-based phase control method offers a new way of eliminating dynamic phase noise in tiled aperture CBC systems,and it could provide a valuable reference on alleviating the long-standing problem that the phase control bandwidth decreases as the number of array elements increases. 展开更多
关键词 coherent beam combining deep learning phase control
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Comprehensive investigation on producing high-power orbital angular momentum beams by coherent combining technology 被引量:6
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作者 Dong Zhi tianyue hou +5 位作者 Pengfei Ma Yanxing Ma Pu Zhou Rumao Tao Xiaolin Wang Lei Si 《High Power Laser Science and Engineering》 SCIE CAS CSCD 2019年第2期88-96,共9页
High-power orbital angular momentum(OAM)beams have distinct advantages in improving capacity and data receiving for free-space optical communication systems at long distances.Utilizing the coherent combination of a be... High-power orbital angular momentum(OAM)beams have distinct advantages in improving capacity and data receiving for free-space optical communication systems at long distances.Utilizing the coherent combination of a beam array technique and helical phase approximation by a piston phase array,we have proposed a generating system for a novel high-power beam carrying OAM,which could overcome the power limitations of a common vortex phase modulator and a single beam.The characteristics of this generating method and the orthogonality of the generated OAM beams with different eigenstates have been theoretically analyzed and verified.Also a high-power OAM beam produced by coherent beam combination(CBC)of a six-element hexagonal fiber amplifier array has been experimentally implemented.Results show that the CBC technique utilized to control the piston phase differences among the array beams has a high efficiency of 96.3%.On the premise of CBC,we have obtained novel vortex beams carrying OAM of±1 by applying an additional piston phase array modulation on the corresponding beam array.The experimental results agree approximately with the theoretical analysis.This work could be beneficial to areas that need high-power OAM beams,such as ultra-long distance free-space optical communications,biomedical treatments,and powerful trapping and manipulation under deep potential wells. 展开更多
关键词 ORBITAL ANGULAR MOMENTUM BEAMS COHERENT beam combination
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Deep-learning-assisted, two-stage phase control method for high-power mode-programmable orbital angular momentum beam generation 被引量:12
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作者 tianyue hou YI AN +8 位作者 QI CHANG PENGFEI MA JUN LI LIANGJIN HUANG DONG ZHI JIAN WU RONGTAO SU YANXING MA PU Zhou 《Photonics Research》 SCIE EI CSCD 2020年第5期715-722,共8页
High-power mode-programmable orbital angular momentum(OAM)beams have received substantial attention in recent years.They are widely used in optical communication,nonlinear frequency conversion,and laser processing.To ... High-power mode-programmable orbital angular momentum(OAM)beams have received substantial attention in recent years.They are widely used in optical communication,nonlinear frequency conversion,and laser processing.To overcome the power limitation of a single beam,coherent beam combining(CBC)of laser arrays is used.However,in specific CBC systems used to generate structured light with a complex wavefront,eliminating phase noise and realizing flexible phase modulation proved to be difficult challenges.In this paper,we propose and demonstrate a two-stage phase control method that can generate OAM beams with different topological charges from a CBC system.During the phase control process,the phase errors are preliminarily compensated by a deep-learning(DL)network,and further eliminated by an optimization algorithm.Moreover,by modulating the expected relative phase vector and cost function,all-electronic flexible programmable switching of the OAM mode is realized.Results indicate that the proposed method combines the characteristics of DL for undesired convergent phase avoidance and the advantages of the optimization algorithm for accuracy improvement,thereby ensuring the high mode purity of the generated OAM beams.This work could provide a valuable reference for future implementation of high-power,fast switchable structured light generation and manipulation. 展开更多
关键词 MOMENTUM ORBITAL beam
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