FSO-Based Space Connectivity Beyond RF Limits

Free-space optical (FSO) communication has emerged as a key enabling technology for future space networks requiring ultra-high-capacity, low-latency, and spectrum-efficient connectivity beyond the limitations of conventional RF systems. This lecture introduces the fundamental principles and motivations of FSO-based communications, with a particular focus on optical inter-satellite links (ISLs) for LEO satellite constellations, integrated space-air-ground networks, and wireless optical interconnects for next-generation AI/HPC data centers.
The lecture covers the characteristics of optical wireless channels in both space and indoor environments, including pointing acquisition and tracking (PAT), atmospheric effects, stochastic channel modeling, alignment challenges, and link reliability issues. System architectures, transmitter/receiver structures, and hybrid RF/FSO approaches are also discussed. In addition to satellite applications, the lecture presents emerging FSO-based wireless rack-to-rack interconnect technologies for data centers, which are attracting significant interest as scalable alternatives to conventional wired optical cabling for ultra-high-throughput computing systems.

Recent advances in AI-driven network optimization, NTN integration, and high-capacity optical networking for future 6G systems will also be presented. The lecture aims to provide both academic researchers and industry engineers with a comprehensive overview of current technologies, practical challenges, and future research directions toward realizing scalable and globally connected optical wireless networks.