Research On Fiber Coupling Stability Of Intersatellite Optical Communication Receiving Terminals

In the research of satellite optical communication in recent years,in order to further improve the laser communication rate,spatial light is required to be coupled into the optical fiber.As the optical communication terminal is in the process of working,it will be affected by the vibration of the satellite platform and the deformation of the rigid body,resulting in an angle offset error between the incident signal beam and the receiving optical antenna.The use of single-mode fiber for spatial light coupling reception results in poor coupling stability due to the small core size.With multi-mode reception,the energy of the fundamental mode is greatly reduced due to the excessive number of modes.For this reason,this paper studies a fiber coupling efficiency solution in recent years and proposes a double-clad fiber-single mode fiber optic taper structure as a spatial light-coupled receiver front end based on the feasibility of engineering applications.Above the premise of qualified value,the coupling efficiency can be guaranteed to have better stability under the vibration environment,and the high performance requirement for the tracking system is also reduced.And for the proposed structure,the mode analysis in the fiber is performed,and the coupling curve of the structure in the vibration environment is deduced.An optical experiment was designed.By simulating the inter-satellite vibration environment,the distribution of the coupling curve between the single-mode fiber and the proposed double-clad fiber-single-mode fiber taper structure in the experimental environment was measured,and the two structures were compared with it's experimental curve.The coupling mode was established with experimental data,and then the average of the bit error rate was simulated under single-mode fiber and double-clad fiber-single-mode fiber taper structure as the front end under Gaussian and uniform vibration.In this paper,through theoretical analysis and experimental measurement,it is demonstrated that the proposed double-clad fiber-single-mode fiber taper structure has better stability compared to the single-mode optical fiber used in current engineering under the vibration environment.The communication system can tolerate a more severe vibration environment.This structure can improve the system's bit error rate stability and reduce the tracking accuracy requirements of the PAT system.