Free Space Optical Communications with Multi-Beam Laser Terminals for Satellites

Abstract

Traditional laser communication terminals are limited to point-to-point links, which constrains their scalability and flexibility for global networks that require simultaneous connections with multiple targets. While multiple single-beam terminals can expand capacity, this approach multiplies Size, Weight, Power, and Cost (SWaPC), limiting scalability. Multi-beam laser communication terminals offer a promising alternative, though the design of an effective beam steering system remains a key challenge. This paper explores the design process of such a system, providing an overview of multi-beam steering literature as well as an comparison and trade-off of existing space-borne multi-beam steering technologies. It also analyzes insights from related fields such as terrestrial laser communications, LiFi, single-beam laser communication, optical cross-connects, radio links, and multiple target tracking. Key system functions are identified and visualized in a function flow diagram, and various design options are evaluated, culminating in a design options tree which serves as a design recipe. Two application scenarios, involving high and low target densities, demonstrate that steering systems based on micro-mirror arrays and spatial light modulators present significant advantages over alternatives. This study offers a comprehensive framework for designing multi-beam steering systems for space-based laser communication terminals.