Pioneering the use of a plenoptic Adaptive Optics system for Free Space Optical Communications

Abstract

In this thesis, an Adaptive Optics proposal is presented and experimentally verified at both laboratory and telescope, with the objective of compensating the atmospheric aberrations in the uplink beam and, therefore, ameliorate Free Space Optical Communication links performance and the generation of Laser Guide Stars for conventional AO systems. The research focuses on the active correction of Ground to Space laser beams (optical links and artificial stars), as downlink communications resemble conventional astronomical observations when applying Adaptive Optics techniques: the light is originated in space and it travels downwards through the atmosphere to the receiver (where the AO system would be placed), whereas the uplink needs to be corrected before existing the launching telescope by measuring the atmospheric wavefront with an a-priori unknown reference source. The uplink pre-compensation entails a scientific and technological challenge. The uplink correction problem was deeply studied by the formulation of all possible solutions, which are properly modelled and simulated with an already existing Adaptive Optics Matlab toolbox, into which new functionalities were coded and integrated (upwards Fresnel propagation, new concept wavefront sensor, etc.). Based on the simulation outcome, the corresponding requirements were formulated for the design of an uplink corrector AO system from the very last element to the control strategy. After the proper hardware acquisition (of both COTS elements and custom-built components), the uplink corrector laboratory scale prototype was built and integrated at IAC laboratory facilities. Finally from January 2019 to May 2019, the Uplink Wavefront Corrector System was integrated at the Optical Ground Station telescope at Teide Observatory, successfully demonstrating the uplink precompensation of the laser beam.