Reconfigurable intelligent surface(RIS)is an emerging meta-surface that can provide additional communications links through reflecting the signals,and has been recognized as a strong candidate of 6G mobile communicati...Reconfigurable intelligent surface(RIS)is an emerging meta-surface that can provide additional communications links through reflecting the signals,and has been recognized as a strong candidate of 6G mobile communications systems.Meanwhile,it has been recently admitted that implementing artificial intelligence(AI)into RIS communications will extensively benefit the reconfiguration capacity and enhance the robustness to complicated transmission environments.Besides the conventional model-driven approaches,AI can also deal with the existing signal processing problems in a data-driven manner via digging the inherent characteristic from the real data.Hence,AI is particularly suitable for the signal processing problems over RIS networks under unideal scenarios like modeling mismatching,insufficient resource,hardware impairment,as well as dynamical transmissions.As one of the earliest survey papers,we will introduce the merging of AI and RIS,called AIRIS,over various signal processing topics,including environmental sensing,channel acquisition,beamforming design,and resource scheduling,etc.We will also discuss the challenges of AIRIS and present some interesting future directions.展开更多
A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operati...A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operation was achieved due to the spatial-hole-burning free nature of Raman gain and was maintained at the highest available pump power by suppressing the parasitic stimulated Brillouin scattering(SBS).A folded-cavity design was employed for reducing the perturbing effect of resonances at the pump frequency.At a pump power of 69 W,the maximum Stokes output reached 20.6 W,corresponding to a 30%optical-to-optical conversion efficiency from 1064to 1240 nm.The result shows that parasitic SBS is the main physical process disturbing the SLM operation of Raman oscillator at higher power.In addition,for the first time,the spectral linewidth of a CW SLM diamond Raman laser was resolved using the long-delayed self-heterodyne interferometric method,which is 105 kHz at 20 W.展开更多
基金This work was supported in part by National Key Research and Development Program of China under Grant 2017YFB1010002in part by National Natural Science Foundation of China under Grant 61871455,61831013.
文摘Reconfigurable intelligent surface(RIS)is an emerging meta-surface that can provide additional communications links through reflecting the signals,and has been recognized as a strong candidate of 6G mobile communications systems.Meanwhile,it has been recently admitted that implementing artificial intelligence(AI)into RIS communications will extensively benefit the reconfiguration capacity and enhance the robustness to complicated transmission environments.Besides the conventional model-driven approaches,AI can also deal with the existing signal processing problems in a data-driven manner via digging the inherent characteristic from the real data.Hence,AI is particularly suitable for the signal processing problems over RIS networks under unideal scenarios like modeling mismatching,insufficient resource,hardware impairment,as well as dynamical transmissions.As one of the earliest survey papers,we will introduce the merging of AI and RIS,called AIRIS,over various signal processing topics,including environmental sensing,channel acquisition,beamforming design,and resource scheduling,etc.We will also discuss the challenges of AIRIS and present some interesting future directions.
基金supported by the National Natural Science Foundation of China(No.62005073)the Program of the State Key Laboratory of Crystal Materials(No.KF2101)+3 种基金the National Key Research and Development Program of China(No.2020YFC2200300)the Program of the State Key Laboratory of Quantum Optics and Quantum Optics Devices(No.KF202207)the Research Funds of Hangzhou Institute for Advanced Study(No.2022ZZ01006)the Hangzhou Agricultural and Social Development initiative Design Project(No.2022ZDSJ0846).
文摘A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operation was achieved due to the spatial-hole-burning free nature of Raman gain and was maintained at the highest available pump power by suppressing the parasitic stimulated Brillouin scattering(SBS).A folded-cavity design was employed for reducing the perturbing effect of resonances at the pump frequency.At a pump power of 69 W,the maximum Stokes output reached 20.6 W,corresponding to a 30%optical-to-optical conversion efficiency from 1064to 1240 nm.The result shows that parasitic SBS is the main physical process disturbing the SLM operation of Raman oscillator at higher power.In addition,for the first time,the spectral linewidth of a CW SLM diamond Raman laser was resolved using the long-delayed self-heterodyne interferometric method,which is 105 kHz at 20 W.
