Mitigation of atmospheric effects by adaptive optics for free-space optical communications

Abstract

Data-rates of long-range free-space optical communication links are deteriorated by atmospheric turbulence which causes power in the bucket fluctuations. In order to compensate for those effects the use of adaptive optics is envisioned. Different solutions have been proposed for the correction. We study here the performances of several compensation methods, encompassing both amplitude and phase and phase-only precompensation. In the case of phase-only precompensation we studied two system designs, one which is dedicated to symmetrical communication systems and the other to dissymmetric systems. In the dissymmetric case we studied two ways of driving the deformable mirror : the use of a Shack-Hartmann wavefront sensor and a model-free phase modulation. For each compensation architecture simulation results covered weak, moderate and strong turbulence conditions.

GEOStar: demonstration of laser guide star adaptive optics for free space optical communications

“…Adaptive Optics (AO) systems can be used to mitigate the effects of atmospheric turbulence. 1,2 This is conceptually clear for the downlink light where the communications light itself can be observed by a wavefront sensor and used as a wavefront reference, however improving the uplink stability is more complicated. It is possible to "predistort" the uplink beam with the inverse of the expected phase aberrations, such that the atmosphere flattens the wave-front.…”

Full characterization of the transmission properties of a multi-plane light converter

“…The ability of shaping light's spatial profile is crucial for several different technologies such as imaging through opaque media [1] and biological tissues [2], classical [3] and quantum [4] communication, and quantum information processing [5].…”

Demonstrated pre-compensation of a focused laser beam with up to 0.27 mrad point-ahead-angle over a 1-km horizontal communication path

“…Pre-compensation is anticipated to be a promising method of increasing the efficiency in uplink communications for Earth-to-GEO optical feeder links. Until now, pre-compensation research has largely been implemented via simulation [1][2][3][4] or in laboratory setups using emulated aberrations 5,6 . Before it can be integrated into optical feeder link systems it requires extensive experimentation using real atmospheric turbulence.…”