Novel laser communications transceiver with internal gimbal-less pointing and tracking

This paper describes a novel laser communications transceiver for use in multi-platform satellite networks or clusters that provides internal pointing and tracking technique allowing static mounting of the transceiver subsystems and minimal use of mechanical stabilization techniques. This eliminates the need for the large, power hungry, mechanical gimbals that are required for laser cross-link pointing, acquisition and tracking. The miniature transceiver is designed for pointing accuracies required for satellite cross-link distances of between 500 meters to 5000 meters. Specifically, the designs are targeting Air Force Research Lab's TechSat21 Program, although alternative transceiver configurations can provide for much greater link distances and other satellite systems. The receiver and transmitter are connected via fiber optic cabling from a separate electronics subsystem containing the optoelectronics PCBs, thereby eliminating active optoelectronic elements from the transceiver's mechanical housing. The internal acquisition and tracking capability is provided by an advanced micro-electro-mechanical system (MEMS) and an optical design that provides a specific field-of-view based on the satellite cluster's interface specifications. The acquisition & tracking control electronics will utilize conventional closed loop tracking techniques. The link optical power budget and optoelectronics designs allow use of transmitter sources with output powers of near 100 mW. The transceiver will provide data rates of up to 2.5 Gbps and operate at either 1310 nm or 1550 nm. In addition to space-based satellite to satellite cross-links, we are planning to develop a broad range of applications including air to air communications between highly mobile airborne platforms and terrestrial fixed point to point communications.