Study On Sensoring Characteristics Of Photonic Crystal Fiber Evanescent Wave

ABSTRACT:Fiber-evanescent wave sensor is a research focus of optical sensor in recent years. Fiber-evanescent wave sensor has many advantages such as simple structure, small volume, high cost-performance and remote analysis, which could be widely applied in biomedical, food testing, environmental testing and biological and chemical warfare agent detection. PCF-evanescent wave sensor is the important research direction of fiber-evanescent wave sensor, PCF has special guiding system and model characteristics, which make it have a lot of advantages that traditional fiber-evanescent wave sensor do not have. So the researches in the PCF-evanescent wave sensor have great scientific and application significance.The theoretical study in transmission properties of the refractive index guided photonic crystal fiber and evanescent wave sensing properties of photonic crystal fiber are discussed in this paper. The summary of the dissertation is as follows:(1) The basic conceptions of photonic crystal and the status of fiber-evanescent wave sensor and photonic crystal fiber sensor are introduced.(2) Numerical simulation methods of photonic crystal fiber are introduced, the finite element method is described in detail.(3) Based on the finite element method, three different types of photonic crystal fibers with different air-hole in cladding region are proposed and investigated. The concept of equivalent refractive index of cladding is introduced from the equivalent refractive index method, which can rule out the false solutions of FEM. For numerical simulation of photonic crystal fibers with FEM, the effect of material dispersion is considered in the transmission properties. The differences of three different photonic crystal fibers' transmission characteristics are discussed.(4) The theories of evanescent wave sensor and the kinds of evanescent wave sensors are introduced first. Based on FEM, we investigated the relative sensitivity of the PCF-evanescent wave sensor and the effect of the structure of pcf. The effect of confinement loss is also considered. We design a THz photonic crystal fiber and a THz porous fiber and investigate the evanescent wave sensing properties of the two THz waveguide.