Free space optics (FSO) has been recognized as a crucial technique to meet the high-bandwidth requirements in future wireless information transmission links. It provides a feasible solution to the last-mile bottleneck problem due to its merits that include high-speed data transportation and secure and low-latency networks. Due to these merits, FSO is a reliable technology for future health-care and biomedical services like the transmission of biomedical sensor signals. But the main limiting factor in the data transmission employing FSO links is adverse atmospheric weather conditions. This research work reports the designing and simulative evaluation of the performance of a high-speed orthogonal frequency division multiplexing–based free space optics link by incorporating wavelength division multiplexing of two independent frequency channels (193.1 THz and 193.2 THz) along with mode division multiplexing of distinct spatial laser Hermite–Gaussian modes (HG01 and HG03). Four independent 20-Gbps quadrature amplitude-modulated data signals are transported simultaneously under different atmospheric weather conditions using the proposed link. Also, the link performance has been investigated for an increasing beam divergence angle.

自由空间光学（FSO）已被公认为满足未来无线信息传输链路高带宽要求的关键技术。由于其优点包括高速数据传输和安全且低延迟的网络，它为最后一英里瓶颈问题提供了可行的解决方案。由于这些优点，FSO 是未来医疗保健和生物医学服务（如生物医学传感器信号的传输）的可靠技术。但使用 FSO 链路进行数据传输的主要限制因素是不利的大气天气条件。这项研究工作报告了通过结合两个独立频道的波分复用对基于高速正交频分复用的自由空间光学链路的性能进行设计和仿真评估 (193. 1 THz 和 193.2 THz）以及不同空间激光 Hermite-Gaussian 模式（HG01 和 HG03）的模分复用。四个独立的 20 Gbps 正交调幅数据信号使用建议的链路在不同的大气天气条件下同时传输。此外，还研究了增加光束发散角的链路性能。