Uplink phase estimation for optical ground-to-GEO links using a Rayleigh laser guide star as a ground layer...

Area of Science:

• Optical Communications
• Adaptive Optics
• Atmospheric Turbulence

Background:

• Ground-to-GEO optical feeder links face limitations due to phase angular anisoplanatism, causing tip-tilt errors and signal fades.
• Previous research utilized downlink intensity for turbulence discrimination, improving tip-tilt estimation.
• Adaptive optics systems are crucial for mitigating atmospheric distortions in free-space optical communications.

Purpose of the Study:

• To enhance tip-tilt estimation and reduce signal fades in ground-to-GEO optical feeder links.
• To investigate the effectiveness of incorporating a Rayleigh laser guide star (R-LGS) for uplink phase estimation.
• To separate ground-layer and upper-layer atmospheric turbulence contributions using a minimum mean square error framework.

Main Methods:

• Incorporation of a ground-layer-dominated Rayleigh laser guide star (R-LGS) measurement.
• Development of a minimum mean square error estimation framework accounting for focal anisoplanatism and measurement noise.
• Utilizing measured urban turbulence profiles for performance evaluation.

Main Results:

• Uplink phase estimation using R-LGS measurements significantly improves tip-tilt estimation.
• Deep signal fades are reduced by up to 24 dB, enhancing link stability.
• Performance gains are particularly pronounced under strong turbulence and high angular decorrelation conditions.

Conclusions:

• Rayleigh laser guide stars offer a practical and low-cost solution for robust GEO feeder-link operation.
• The proposed method effectively mitigates atmospheric turbulence effects, improving optical communication reliability.
• This approach demonstrates significant potential for enhancing satellite communication systems.