Research On The Automatic Coupling Of Space Light To Single Mode Optical Fiber In Satellite Optical Communication Terminal

In today’s rapid development of social science and technology.In most time human beings’ needs will go beyond the current level,as same as in the field of communication.People are always eager to exchange information more quickly, and the speed of the network is constantly updated to meet the needs of human beings.At present, human beings mainly use microwave communication, but the microwave communication is facing a bottleneck and it is difficult to make outstanding progress.So the satellite optical communication is found to conform to the trend of the times.But the satellite optical communication is still in the initial stage, the distance from the real commercial use may be need a long time to reach.The stability and reliability of the communication quality is very important in the satellite optical communication, and the coupling of the space light to the single mode fiber is an important factor to restrict the quality of the communication.Only when the space light can be efficiently coupled to a single mode optical fiber,it can be carried out in the light amplification and filtering processing and other follow-up work can be done to fully guarantee the quality of communication.Because the core of single mode fiber is very small,any tiny change can have a huge effect on the coupling efficiency.The coupling efficiency of spatial light to single mode fiber is mainly affected by two aspects, one is the coupling pattern matching problem, and the other one is the alignment of the light and the optical fiber.According to the mode matching principle, the paper derives the formula of coupling efficiency and the related simulation, in combination with the offset problem of the possible single-mode fiber are discussed, and derived formula of coupling efficiency in the presence of various drift.In view of the influence of the coupling efficiency, the control algorithm is used to control the spatial light to the single mode optical fiber automatically.In space light to single mode optical fiber automatic coupling control the most important part is the selection of control algorithm.This paper mainly uses the pattern search method and particle swarm optimization algorithm to compare and analyse.First of all, the relevant coupling efficiency formula are used to do the simulation of the two optimization algorithms, to compare the performance of the two algorithms in the simulation.In the simulation, the search times and the final results of each method can be referenced. The particle swarm optimization algorithm has a strong ability to resist external interference and will not be affected too strongly.On the contrary, the pattern search rules are easy to be affected by the interference of the outside world and make the search times change with the size of the interference.During the experiment, a random disturbance is generated by using a fast steering mirror in the light of the coupling to a single mode optical fiber.In order to ensure that the couplingefficiency is at a high level, the two algorithms are used to adjust the single mode fiber’position.The experimental results show that the particle swarm optimization algorithm is more reliable than the pattern search algorithm to compensate the loss of the single mode optical fiber.