Free space optical (FSO) transmission has emerged as a key candidate technology for 6G to expand new spectrum and improve network capacity due to its advantages of large bandwidth, low electromagnetic interference, and high energy efficiency. Resonant beam operating in the infrared band utilizes spatially separated laser cavities to enable safe and mobile high-power energy and high-rate information transmission but is limited by line-of-sight (LOS) channel. In this paper, we propose a reconfigurable intelligent surface (RIS) assisted resonant beam simultaneous wireless information and power transfer (SWIPT) system and establish an optical field propagation model to analyze the channel state information (CSI), in which LOS obstruction can be detected sensitively and non-line-of-sight (NLOS) transmission can be realized by changing the phased of resonant beam in RIS. Numerical results demonstrate that, apart from the transmission distance, the NLOS performance depends on both the horizontal and vertical positions of RIS. The maximum NLOS energy efficiency can achieve 55% within a transfer distance of 10m, a translation distance of $\pm$4mm, and rotation angle of $\pm$50{\deg}.

翻译：自由空间光传输凭借其大带宽、低电磁干扰和高能效等优势，已成为6G扩展新频谱和提升网络容量的关键候选技术。工作于红外波段的谐振光束利用空间分离的激光腔实现安全可移动的高功率能量与高速率信息传输，但受限于视距信道。本文提出一种可重构智能表面辅助的谐振光束同时无线信息与功率传输系统，并建立光场传播模型以分析信道状态信息。在该系统中，视距遮挡可被灵敏检测，并通过改变谐振光束在可重构智能表面上的相位实现非视距传输。数值结果表明，除传输距离外，非视距性能还取决于可重构智能表面的水平与垂直位置。在传输距离10米、平移距离±4毫米及旋转角±50°的范围内，非视距最大能量效率可达55%。