1550-nm combined transmission booster amplifier and receiver preamplifier for satellite to satellite laser communication

Satellite-to-satellite laser communication technology underpins high-speed l0-Gbps optical links for the new generation of satellite constellations that will serve as global telecommunications networks. LEO satellite-to-satellite links may extend over distances of >5000 km, necessitating an optical-power budget of ~70 dB to compensate for diffraction-limited opticalbeam divergence. This can be achieved by boosting the transmitted laser diode signal to around 1 W, and by amplifying the received signal by 40 dB. Such performances are attained by terrestrial fiber amplifiers, operating in the telecom 1550- nm wavelength window, which are produced in volume of thousands and are (in relative terms) of low cost. Based on MPBC’s large volume production experience of fiber amplifiers and its heritage of space system design and manufacturing, a new product line of Laser Communication Terminals (LCTs) for space is presented. It is designed to be lower cost, exploiting commercial off-the-shelf (COTS) components whenever possible. Most of these fiber-optic components are extensively employed in large terrestrial telecom equipment and are already qualified to telecommunications standards. However, additional tests are required to ensure reliable long-term operation in a space environment. We have subjected the components, both active and passive, to gamma- and proton-radiation tests including total ionization doses of up to 100 kRad, Temperature vacuum cycling over extended temperature range have been performed and are still ongoing. Finally, considering manufacturing costs, we are packaging both the transmission optical booster unit and receiver optical amplification unit in the same housing, in order to co-locate both the transmit and receive functions of the link. These units are compact and stackable and save on the enclosure weight.