The Propagation Properties Of Parity-Time Symmetric Photonic Crystal Waveguides

Photonic crystal waveguides are the basic components of many optical devices because of their special photonic band structure.They play an important role in the fields of nonlinear optics,optical logic gates,all-optical cache,slow light waveguides,photonic crystal lasers and high sensitivity sensors.In recent years,Parity-time(PT)symmetry structure has been widely used in the field of optics because of its special optical properties,and a number of excellent achievements have emerged.The main idea of this thesis is to combine photonic crystal waveguide with PTsymmetry structure to design a PT-symmetry structure photonic crystal waveguide with special transmission properties.For example,two kinds of PT-symmetry photonic crystal waveguides with different properties are obtained by introducing different PT-symmetry structures in the twodimensional photonic crystal waveguides.In addition,PT-symmetry microcavity structure is also introduced into one-dimensional photonic crystals.The special sensing mechanism of the structure was found.Based on this,a sensor was designed to measure the blood glucose concentration of human body.In this thesis,a PT-symmetry structure is introduced in a two-dimensional photonic crystal waveguide.The mode evolution and coupling of the waveguide with PT-symmetry structure are theoretically analyzed by introducing PT-symmetry structure at the edge of the waveguide.At the same time,singularities are found in the energy band of the waveguide,and the properties of the singularities are studied by COMSOL simulation software.Finally,we replace all the dielectric columns on both sides of the waveguide with those with PT-symmetry structure.In this waveguide structure,we find a special waveguide mode,which is embedded in the passband but retains the properties of the waveguide mode,and we call it a new local state.We also use COMSOL software to analyze the properties of the special mode and study the transmission properties of the structure waveguide.In addition to introducing PT symmetry structure into two-dimensional photonic crystals,a coupled resonator system based on PT-symmetry structure was constructed.Through structural optimization,the system reached the pole state of PT-symmetry.Based on the linear relationship between blood glucose concentration and blood refractive index,since the transmission of the pole-state system is very sensitive to blood glucose refractive index,the measurement of blood glucose concentration is converted into the measurement of system transmission,so as to achieve the purpose of blood glucose sensing.A sensor is designed to measure blood glucose concentration in human body.By adjusting the input of the sensor,the sensor can switch between measuring low blood glucose concentration and high blood glucose concentration.