Design And Performance Optimization Of Optical Fiber Based On Orbital Angular Momentum

With the continuous development and improvement of 5G,6G,big data and other network technologies,people put forward new requirements for the capacity of optical fiber communication.However,the communication capacity of the traditional single-mode fiber for communication is close to the Shannon limit.Therefore,it is very important to find a new multiplexing method to support high-capacity communication.In theory,there are infinite orthogonal bases for the orbital angular momentum of different topological charge numbers carried by vortex optical rotation.If this property is fully utilized,the orbital angular momentum(OAM)can exist as a new multiplexing degree of freedom,so as to greatly improve the capacity of optical fiber communication.Consequently,the current research focus is to study the communication optical fiber that can support as many OAM modes as possible and ensure its excellent optical fiber performance.Based on the previous related research,this paper designs several optical fiber structures by using the finite element analysis software COMSOL,realizes the high-capacity optical fiber communication,and summarizes the universal parameter design and performance optimization rules by using several simple structures.The main achievements are as follows:Firstly,the optical OAM and the OAM modes transmitted in optical fiber are explained mathematically,and then a photonic crystal fiber(PCF)which can transmit 118 OAM modes in the range of 1.2 μm to 1.65 μm has been designed,and its performance is studied.Then,utilizing two simple structures,the effects of the thickness of the ring region of the fiber on the properties of effective index difference,dispersion,effective mode area,nonlinear coefficient,numerical aperture,mode purity,walk off length and confinement loss,and the effects of structural parameters such as the shape,size,number,the number and spacing of cladding pores on dispersion and confinement loss are studied respectively.Moreover,using the universal rules of parameter design and performance optimization obtained from the two structures,a PCF supporting 394 orbital angular momentum modes with high performance in1.48-1.62 μm is proposed.In addition,a circular anti-resonance fiber(ARF)supporting 30 OAM modes is proposed,which has extraordinarily low confinement loss.Several optical fiber structures for transmitting OAM modes are proposed in this paper and they can improve the communication capacity of OAM mode division multiplexing system to a certain extent.The summarized universal parameter design and performance optimization laws can provide reference for designing fiber parameters and optimizing fiber performance in the future.The research results proposed in this paper have important potential value in the field of modern optical fiber communication.