Study On The Theory And Simulation Of Hollow Core Anti-resonant Fiber

With the continuous growth and rapid development of the global Internet communcation,Internet of Things and other communication requirements,there is a growing demand for the transmission capacity of optical fiber communication systems.The transmission capacity of optical fiber communication systems can be improved by using technologies such as multidimensional optical signal multiplexing and high-order modulation.However,the material nonlinearity of traditional solid-core optical fiber makes it difficult to increase the capacity and has a capacity limit,which is called nonlinear Shannon limit.In addition,in other optical fiber application fields,solid-core optical fiber also shows some limitations due to the intrinsic properties of material.In order to overcome the material defects of solid-core optical fibers,hollow core fibers using air as the light-guiding medium have been proposed and extensively studied.Hollow core fibers have the advantages of low transmission lantency,low dispersion,small nonlinear coefficient,and high power damage threshold.It is a potential ideal transmission fiber that can replace traditional solid-core fiber and break through the limit of fiber nonlinear capacity.Meanwhile,hollow core fibers have broad development prospects in many application scenarios,such as gas sensing,mid-infrared laser,and precision machining.Compared with other types of hollow core fibers,hollow core anti-resonant fibers have unique advantages such as low transmission loss,wide operating band,as well as simple structure,and have become a research hotspot in recent years.At present,the related research on hollow core anti-resonant fibers is still in the early stage.In terms of theoretical research,the existing theoretical models of low loss hollow core anti-resonant fibers still face the problems of narrow operating bandwidth and high complexity structure.In the design of single-polarization hollow core anti-resonant fiber,the reported research mainly focuses on the polarization loss ratio,and there are few studies on the low loss of single-polarization fiber.Aiming at these problems,a novel theoretical model of hollow core anti-resonant fiber has been proposed,and the performance of proposed fiber have been simulated and analyzed.The main work is as follows:1.A novel model of hollow core anti-resonant fiber with U-shaped nested structure is proposed.The confinement loss of proposed fiber is nearly one order of magnitude lower than nested anti-resonant nodeless fiber,which is lower than 0.01 d B/km over 550 nm bandwidth ranging from 1.3 ?m to 1.85 ?m.Through theoretical analysis of mode coupling,the proposed fiber can achieve excellent wideband single-mode performance with high-order mode loss ratio exceeding 100,000 over the entire operating band.2.A novel model of low loss single-polarization hollow core anti-resonant fiber is proposed,which has a confinement loss lower than 1 d B/km in the single-polarization operating band of 10.8 nm and maintains good single-mode performance.The proposed fiber has a polarization loss ratio of 50.3 d B and a confinement loss of 0.44 d B/km at 1543.2 nm,with low loss and good single-polarization single-mode performance.