Performance assessment of adaptive optics techniques on FSO communications through the atmosphere

Abstract

Free Space Optical Communications have demonstrated in the recent years to be a feasible alternative to the radiofrequency links due to their advantages in terms of mass, power, cost and exibility. Since 1995, the Optical Ground Station (OGS) at the Teide Observatory is used by ESA to test laser communication terminals on board of LEO and GEO satellites; however, as one side of the link is settled on the Earth surface, the communication performance will suffer from the effects of the atmosphere presence. The use of adaptive optics in both uplink and downlink, and even the use of Laser guide stars, will then contribute to improve link quality parameters. The approach of pre-correcting the uplink with a Deformable Mirror is also applicable to the Laser Guide Star self-propagating path and the fact a LGS will also narrow its beam with AO correction makes possible a more focused spot with lower magnitude up on the sky. With the aim of designing an Adaptive Optics system in the near future to improve the FSO links at the OGS and possibly the quality of LGSs, turbulence conditions regarding both uplink and downlink have been simulated. Expected performance of a proposed AO system to reduce atmospheric aberrations in both propagating directions is also analysed, as well as the application to LGSs and its advantages in comparison to conventional AO.