Study On Transmission Characteristics Of Dual-Mode Hollow-Core Anti-Resonant Fiber And Refractive Index Sensor

Low-loss transmission of O-L telecommunication band can be achieved in hollow-core anti-resonant fiber,which makes hollow-core anti-resonant fiber to be a favorable candidate for data transmission.Meanwhile,the excellent optical properties such as low loss,low differential delay,low nonlinear coefficient of hollow-core anti-resonant fiber,as well as the absence of distortion when the signal is transmitted through such fiber,which make the few-mode hollow-core anti-resonant fiber for an effective way to improve the transmission capacity of the system.How to design a dual-mode or even few-mode hollow-core anti-resonant fiber that can achieve low-loss transmission of communication frequency band,which becomes one of the research hotspots.In this paper,the full-vector finite element method is used to study the mode coupling characteristics and transmission characteristics of hollow-core anti-resonant fiber.In addition,the refractive index sensor based on hollow-core anti-resonant fiber is also studied.Firstly,the background and practical significance of this research are introduced,and the low loss current research progress of hollow-core anti-resonant fiber at home and abroad is reviewed.Meanwhile,anti-resonant reflection optical waveguide model and mode coupling principle model of the hollow-core anti-resonant fiber are introduced,the full-vector finite element simulation method is described.The characteristics of hollow-core anti-resonant fiber are also introduced.Secondly,by studying the core-cladding mode coupling characteristics of hollow-core anti-resonant fibers with different cladding structures,multi-mode hollow-core anti-resonant fibers transmitted at 1.94μm in the medical band are designed.The types of fibers include single-layer tube,nested circular tube,nested straight sheet,nested curved sheet with circular clad tube,and elliptical clad tube with nested curved sheet hollow-core anti-resonant fiber.Thirdly,by studying the confinement loss characteristics and bending characteristics of hollow-core anti-resonant fibers with different cladding tube structures,the low-loss transmission of LP₀₁and LP₁₁modes are obtained.The hollow-core anti-resonant fiber realizing dual-mode transmission in the communication band is designed.Finally,based on the dual mechanism of bending loss and surface plasmon resonance,the refractive index sensor of hollow-core anti-resonant fiber is designed.The effects of core diameter,cladding tube diameter,cladding tube thickness,gold layer thickness and bending direction on the sensitivity of the sensor are systematically studied.