Free-space laser downlinks have the potential to provide high data rates in space-to-earth communications and become a key enabler of future optical information systems in space. However, when a downlink passes through the atmosphere, clear-air turbulence induces serious phase distortion and fading. Here, we show how field conjugation adaptive arrays may function in downlink optical communications, overcoming the limitations imposed by the atmosphere by adaptively tracking and correcting atmospherically distorted signals. The goal of this analysis is to provide measures of performance related to practical downlink coherent receivers using adaptive compensation of atmospheric effects. The analysis reveals that for typical downlink conditions, substantial system performance gains can be obtained using only a small number of apertures, supporting use of the proposed array receivers in future space-based optical communication systems.

Peer Reviewed