Research On Performance Of OAM Communication System Based On Fiber Coupling Receiver

In recent years,people have increasingly demanded high-speed communications.However,the communication capacity of current communication systems has reached the limit,and it is necessary to develop new technologies to increase the communication capacity.The orbital angular momentum of the beam provides a worthwhile new method for improving the communication capacity of free space optical communication.The OAM beams with different l have orthogonality,which can be used in a multiplexed communication system to increase the communication rate.Therefore,after the OAM-carrying beam has been proved to be able to modulate and transmit information,researchers have set off a research boom in the application of OAM beam to optical communication systems.The OAM optical communication system is divided into free-space optical communication and optical fiber communication.In free-space optical communication,OAM-carrying light is affected by the offset of the receiving end of the communication system in the transmission process,causing mode crosstalk and affecting the quality of communication.Therefore,in this paper,the mode crosstalk and fiber coupling efficiency of the OAM-carrying beam are studied for the offset of the receiving end of the communication system,and then the BER of the system is analyzed.The main content of this article:(1)This article has discussed the current research status of OAM-carrying beams used in optical communications by researchers,introduced the basic knowledge of orbital angular momentum and used MATLAB tools to simulate the intensity distribution and phase distribution of LG-carrying beams;(2)This paper has described the existence of offsets(lateral offsets and angular offsets)at the receiving end of the communication system,and derived the expression of the beam at the receiver's offset,and analyzed the principle of pattern crosstalk.More importantly,we have simulated the crosstalk of OAM beams with different topological charges(l)when the receiver has different offsets,and obtained the relative power of the OAM beam,and analyzed the simulation results.(3)This paper also has introduced the basic model of spatial light coupling to the fiber and the existence of OAM-carrying light in the fiber.We have derived the model of OAM-carrying light coupling to the ring fiber,calculated the fiber coupling efficiency under different offsets.At the end of the third chapter,the graph of the coupling efficiency of optical fibers with different offsets is plotted and analyzed.(4)We have discussed the effects of different offsets on the bit error rate of the system,drawn and analyzed the graphs of the bit error rate and different offsets.Finally,this paper have analyzed the effect of fiber coupling efficiency and bit error rate on the communication system from the perspective of receiver offset.The results provide reference for research on OAM optical communication systems in the future.