Design And Study Of Photonic Crystal All-Optical Switches

The photonic crystal is the optical analogue of the semiconductor, the concept of which was proposed by John,a Canadian physicis who was studying the relationship between the photonic localization state and the refractive coefficient,and Yablonovitch,an Australian physicist who was doing research on the radiative properties of materials, both of whom found that the properties of photonic modes would change with relation to the periodical variation of permittivity. The proposition of photonic crystal shows a new mechanism of controlling photons which is completely different from utilizing total refraction to guide the propagation of light before.Devices made of photonic crystal can control the flow of photons as people wish and display unprecedented developing prospect and application potential just like electrons in semiconductor,as the result of which,theoretical researches,related experiments and practical applications of photonic crystals have developed rapidly and became a research hotspot worldwide.The dissertation mainly consists of the following parts:1. The concept,properties,preparation methods and application of photonic crystals are introduced comprehensively.Moreover,the major research methods are included,especially the plane wave expansion method and finite difference time domain method used by the dissertation which are detailed.2. The current state of photonic crystal research is discussed here. The energy band of a structure of square lattice is calculated with plane wave expansion method, and the frequency spectrogram of a photonic crystal ring resonator with the finite difference time domain method,leading to the resonant frequencies. We also propose a a coupled structure consisting of a single waveguide and a ring resonator, a theoretic analysis of which is conducted and based on which a photonic crystal all-optical switch of extremely high switching efficiency is designed.3. A coupled structure consisting of two waveguides and a ring resonator is presented and the qualitative discussion and quanlitative analysis of it are detailed,leading to the transfer characteristic of it.Based on the work above,we propose a photonic crystal all-optical switch of high switching efficiency.4. The dispersion relation of a waveguide system consisting of two waveguides is calculated with the finite difference time domain method,and the optical transfer characteristic of it is studied. On this basis,we present a photonic crystal all-optical switch of compact structure and high switching efficiency based on a waveguide coupling structure.