Study On Polarization Properties Of Hollow Core Anti-resonance Fibers Used In Near Infrared Band

As the application requirements of infrared fibers in the field of high energy transmission growing,the requirements for the polarization characteristics of such optical fibers have also increased for today.Compared with solid-core fibers,hollow core fibers have advantages of high damage threshold,low nonlinearity and low material absorption.Therefore,hollow core anti-resonance fibers is a research hotspot of optical fiber filed.How to design a hollow core anti-resonance fiber with excellent polarization characteristics is a key technique that needs to be solved urgently.In this thesis,we simulate the polarization characteristics of hollow core anti-resonant fiber by the full vector finite element method.At the same time,we design single-mode singlepolarized hollow core anti-resonant fiber and high-birefringent hollow core antiresonant fiber.Firstly,we briefly introduce the research background,significance of the project and the current research status of hollow core anti-resonant fiber at home and abroad.We also describe the guidance mechanisms that anti-resonant reflection and inhibition mode coupling of hollow core anti-resonant fiber.Besides,the related theoretical knowledge about the full vector finite element simulation method is introduced.Secondly,the characteristics such as the birefringence,polarization extinction ratio and confinement loss of hollow core anti-resonance fibers with different structures are studied.We study hollow core anti-resonant fiber of the core with elliptical shape,by changing the ellipse core of aspect ratio,core area and cladding tube shape to study the change of polarization characteristics.We do some experiments to present the polarization characteristics of polarization maintaining hollow core anti-resonant fiber.Thirdly,a method for gaining polarization extinction ratio by coupling the core mode with the surface mode of the cladding tube is proposed.We design a single-mode single-polarization hollow core anti-resonance fiber for operation wavelength of 2940 nm,and give the design process of the fiberFinally,we propose a hollow core anti-resonance fiber of two cladding structure.By changing the geometric parameters of the inner cladding tube,the outer cladding tube and the fiber core,we study the mode coupling for core mode with the surface mode of inner cladding tube and the tube of outer cladding,and design a high birefringence hollow core anti-resonance fiber.