Coherent optical feeder links for very high throughput satellite systems

Abstract

Satellite-to-ground optical feeder links are envisioned in the framework of Very-High-Throughput-Satellite (VHTS) systems. Such optical feeder links need to provide aggregated useful data rates in the range of several hundred Giga-bitsper-second (Gbps). To reach this goal, one of the required fundamental technologies consists in the transmission of more spectrally and energy efficient modulation format relying on coherent intradyne detection. The latter enables complex modulation formats and the use of both polarizations of the signal to transmit polarization-multiplexed data streams. Such coherent intradyne transceivers commonly used for fiber-based applications rely on digital signal processing to recover information after having compensated a range of transmission impairments. Free-space optical communication through the atmosphere for satellite-to-ground link presents fundamentally different characteristics from which stem deleterious impairments to the signal's quality. We present an investigation through end-to-end simulations of the performance of coherent transceivers for use in optical feeder links based VHTS systems. To base our analysis on realistic channel conditions, we use data acquired during the first demonstration of an adaptive optics (AO) pre-compensated uplink to a Geosynchronous (GEO) satellite as well as data generated by a representative laboratory emulator.