Design of satellite terminal for Ballistic Missile Defense Organization (BMDO) lasercom technology demonstration

Laser communications offers the potential for transferring information at data rates higher than 1 Gigabit per second (Gb/s) between satellites, aircraft, and ground sites using terminals with weights between 15 and 30 pounds, and volumes less than 1 cubic foot. The Ballistic Missile Defense Organization (BMDO), contracting through the U.S. Army Space and Strategic Command, has been funding the development of laser communications technology and demonstration hardware. Applications of near term interest include inter-satellite crosslinks, Low Earth Orbit satellite downlinks to the ground, and Aircraft-to-Aircraft crosslinks. To demonstrate the capability and readiness of laser communications for these applications, we are building a space capable laser communications terminal to be flown on BMDO's STRV-2 experiment with a projected launch date in 1997. The design of that terminal is based on direct modulation of semiconductor lasers, direct detection using avalanche photodiodes, separate acquisition/tracking and communications wavelengths, separate transmit and receive apertures, and a simple optical transceiver package mounted on a hemispherical field of regard gimbal.