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Proceedings Paper • Open Access

Demonstrated pre-compensation of a focused laser beam with up to 0.27 mrad point-ahead-angle over a 1-km horizontal communication path
Author(s): A. Brady; N. Leonhard; C. Rößler; M. Gier; P. Böttner; C. Reinlein

Paper Abstract

In the development of laser communication networks, atmospheric turbulence remains an obstacle in the efficiency optimisation of bidirectional optical links. Post-compensation of the downlink signal through adaptive optics (AO) has been verified as a method of increasing the efficiency of satellite-to-ground optical links, however, similar efficiencies have yet to be achieved in the opposite direction (uplink) largely due to the shower curtain effect and the consequent impossibility of conducting post-compensation over the smaller receiver aperture at the satellite terminal. Pre-compensation is anticipated to be a promising method of increasing the efficiency in uplink communications for Earth-to- GEO optical feederlinks, by pre-distorting the uplink wavefront prior to propagation through the atmosphere using measurements of the downlink. Here, we present the recent modifications to our current experimental setup and initial results of a pre-compensation experiment conducted over a 1 km horizontal path. The experiment aimed to investigate pre-compensation under a point-ahead-angle for the special case of a focussed uplink beam. Two optical terminals were developed, a “ground terminal breadboard” (GTB) consisting of a commercially available 30 cm reflective telescope in combination with an AO-box [3] capable of simultaneous post-and pre-compensation and a “satellite terminal breadboard” (STB) with separate transmission and receiving apertures for measurement of the uplink beam under a point-ahead-angle (PAA). We present a first look at and discussion of the experimental results which show that AO pre-compensation increased the measured intensity of the uplink beam over the receiving aperture of the STB for a PAA of up to 0.27 mrad.

Paper Details

Date Published: 12 July 2019
PDF: 9 pages
Proc. SPIE 11180, International Conference on Space Optics — ICSO 2018, 111801E (12 July 2019); doi: 10.1117/12.2535969
Show Author Affiliations
A. Brady, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
N. Leonhard, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
C. Rößler, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
M. Gier, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
Ernst-Abbe-Hochschule Jena Univ. of Applied Sciences (Germany)
P. Böttner, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
C. Reinlein, Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)


Published in SPIE Proceedings Vol. 11180:
International Conference on Space Optics — ICSO 2018
Zoran Sodnik; Nikos Karafolas; Bruno Cugny, Editor(s)

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