Design And Study Of A New Kind Of Photonic Crystal Fiber With Micro-structure Cladding For OAM Modes Transmission

With the rapid growth of the communications industry,the demand for channel capacity has increased correspondingly.To make a breakthrough in the bottleneck of channel capacity and cater to the next general communication system of 5G/6G,the concept of using the orbital angular momentum?OAM?of light beams as an information carrier has been proposed.Some typical type of photonic crystal fibers?PCF?show positive performance in transmitting OAM light beams.Designing a kind of PCF with good transmission qualities for OAM light beams has become a hot research issue.Mode properties,such as dispersion and confinement loss,can be optimized in some ways.In this paper,with the purpose of improving the dispersion and confinement loss qualities,a common kind of PCF is selected as the original structure.And a series of tests are done to explore the relationships between dispersion/confinement loss and the design of cladding area.Two creative ideas are proposed to improve these two transmission qualities respectively——inserting micro-structures and extending outer-cladding air-holes.Combining two ideas above,a new type of PCF with optimized structure is proposed.Simulation results show this PCF can stably transmit 30OAM modes with very low dispersion level in a range from 50 to 110 ps/?nm*km?at 1.55?m and low confinement loss level in an estimated range from 10^-15to 10^-10d B/m.The structure of the optimized PCF can be designed flexibly,and this new type has great potential in improving transmission qualities.