Tip tilt and focus estimation based on LGS and downlink joint measurements for ground to GEO satellite optical communication link

Lognoné, Perrine; Rekaya, Ghaya; Montmerle-Bonnefois, Aurélie; Paillier, Laurie; Conan, Jean-Marc

Abstract

Achieving high data rates in GEO Feeder optical uplinks faces challenges due to the fading nature of the channel induced by atmospheric turbulence. Adaptive optics pre-compensation using downlink measurements is a solution to mitigate the impact of the turbulence. However, the point-ahead angle anisoplanatism, inherent to the bidirectional link geometry, limits the uplink correction efficiency, leading to persistent signal fades and loss of information onboard the satellite. We recently proposed a new minimum mean square error method that improves the phase estimation at the PAA based on the downlink phase and log amplitude measurements, reducing the anisoplanatism impact on the coupled flux. Alternatively, a laser guide star can be used to measure the phase at the PAA. However, it is currently challenging to retrieve the tip, tilt, and focus modes, whose correction is essential to improve the link quality. In this article, we propose to combine both techniques to estimate the tip, tilt, and focus at the PAA by incorporating the LGS high-order measurements in the MMSE formalism. We develop the associated analytical reconstructor and evaluate the performance of the phase estimation and the gain on the coupled flux statistics aboard the GEO satellite, considering an idealized LGS system. The new estimator is shown to reduce the tip, tilt, and focus error variances by up to 70% of their initial value.

Citation

Lognoné, P., Rekaya, G., Montmerle-Bonnefois, A., Paillier, L., & Conan, J.-M. (2024). Tip tilt and focus estimation based on LGS and downlink joint measurements for ground to GEO satellite optical communication link. Optics Express, 32(21), 37739-37757. https://doi.org/10.1364/oe.538333

• Journal Article Type: Article
• Acceptance Date: Sep 26, 2024
• Online Publication Date: Oct 3, 2024
• Publication Date: Oct 7, 2024
• Deposit Date: Oct 10, 2024
• Publicly Available Date: Oct 10, 2024
• Journal: Optics Express
• Electronic ISSN: 1094-4087
• Publisher: Optica
• Peer Reviewed: Peer Reviewed
• Volume: 32
• Issue: 21
• Pages: 37739-37757
• DOI: https://doi.org/10.1364/oe.538333
• Public URL: https://durham-repository.worktribe.com/output/2953112