Analysis of adaptive optics-based telescope arrays in a deep-space inter-planetary optical communications link between Earth and Mars

Earth-based telescope array receivers employing optical communications have the potential to fulfill the communication needs of technologically sophisticated, deep-space exploration missions. Atmospheric turbulence is the chief restrictive factor in an optical deep-space channel (ODSC). In this paper, investigation and design of adaptive optics (AO) subsystems are presented for the compensation of the coupled effects of optical turbulence and background noise in telescope array receivers. An end-to-end simulation platform for an ODSC between Mars and Earth is implemented, which incorporates pulse-position modulation (PPM), direct-detection receivers, and detectors with the capability of detection of single photon. The extreme conditions of atmospheric turbulence and background noise are also modeled in the analysis. AO subsystems are incorporated at individual telescopes in the array receiver to mitigate the turbulence effects. The performance of array receivers is evaluated in terms of the probability of error and communication throughput. The analysis in this research depicts that in worst-case turbulence and background noise conditions, inclusion of AO systems results in 8.5 dB performance improvement in communication data rates. The performance improvement of 5.6 dB is achievable in moderate channel conditions. Comparison of performance of array receivers with that of a large monolithic telescope shows that incorporation of AO systems is more feasible in arrays comprising telescopes with relatively smaller diameters.