Study On Transmission Characteristics And Related Sensors Of Hollow Core Negative Curvature Fiber

With the development of optical fiber communication technology,the demand for various special optical fibers is gradually increasing.Hollow core negative curvature fibers have attracted a lot of interests because they have many advantages compared with the silica core fiber.So it is important for the researchers to design the fibers with excellent transmission characteristics and widen the applications of hollow core negative curvature fiber.In this thesis,we simulate the transmission and sensing characteristics of hollow core negative curvature fibers by the full vector finite element method.Firstly,we briefly introduce the research background,significance of the project and the current research status of hollow core negative curvature fiber at home and abroad.We also describe the guidance mechanisms that anti-resonant reflection and inhibition mode coupling of hollow core negative curvature fiber.And the related theoretical knowledge about the full vector finite element simulation method is also introduced.Secondly,the transmission characteristics such as confinement loss,bending loss and single-mode properties of hollow core negative curvature fibers with different structures are studied.We studied the effect of the single cladding tube with circular and elliptical shape,as well as transmission characteristics of the different nested tubes.Thirdly,a temperature sensor based on hollow core negative curvature fiber is designed.According to the refractive index changed with temperature of thermosensitive liquid and the surface plasmon resonance of the gold layer,the coupling between the core mode and surface plasmon resonance polariton induces the loss peaks.We can obtain the sensitivity by the drift of the peaks with the temperature increasing.Finally,a refractive index sensor based on hollow core negative curvature fiber is also designed.We studied the effect of the wall thickness of the circular cladding tube,the gap between adjacent cladding tubes and the ellipticity of the elliptical cladding tube on the sensitivity of the refractive index sensor.