Parameter-free fiber coupling method for inter-satellite laser communications based on Gaussian approximation

Satellite constellation networks play a pivotal role in making Beyond 5G services universally accessible to people worldwide. Inter-satellite laser communication is a crucial component of satellite communication networks. To utilize fiber amplifiers, it is imperative to couple the free-space optical beam into a single-mode fiber. However, vibrations and non-coaxial errors significantly impact coupling efficiency, thereby affecting communication quality. We have developed a parameter-free fiber coupling method based on Gaussian approximation to rectify non-coaxial errors and mitigate incident angle deviations induced by vibrations, ensuring consistently high coupling efficiency. This method is fast, stable, and parameter-free, eliminating the need for manual intervention. Furthermore, experimental results demonstrate the method's effectiveness across the entire correction range of the correction device. In environments with strong vibrations, the communication link experiences a bit error rate of 6.734 E-2, which is reduced to zero bit errors after implementing this method in a closed loop.