Study On The Sensing Properties Of One-Dimensional Annular Photonic Crystal With Defect State

In recent years,the study of artificial microstructure materials such as photonic crystals is very extensive.Because of its special bandgap characteristics and photonic local characteristics,the transmission of photons can be manually controlled.The unique optical properties of photonic crystals have opened up a new path for the development of photonics,and have important application value in many fields.In this paper,photonic crystals are applied to sensing technology.The paper mainly includes the following aspects:Firstly,the basic concepts,classification and basic characteristics of photonic crystals are studied from the basic theoretical knowledge of photonic crystals.By applying the electromagnetic wave Maxwell equation,the reflection law and the refraction law of the light in the medium and the Fresnel equation are analyzed.The eigenvalue equation of photonic crystals is introduced.The theoretical method of photonic crystal is studied,and the derivation process of transmission matrix method and finite element method is introduced in detail.By using these two methods,On the basis of the given structure,the conditions of the photon crystal optical properties such as the transmittance,reflectivity,dispersion relation and group velocity of the photonic crystal can be obtained.The coupling effect between different defect modes is also described.Secondly,the basic theory and research methods of photonic crystals are used to study the optical properties of typical one-dimensional photonic crystals.The influence of the refractive index,thickness,the number of cycles and the incident angle of light on the optical transmission characteristics of a typical one-dimensional photonic crystal is analyzed.On this basis,the doping method of the photonic crystal is introduced.The difference of the two doping modes is compared with the electric field characteristics.The optical resonance principle and the Prague condition of the defect peak are analyzed.Furthermore,the influence factors of the optical properties of the photonic crystals with the doping type are studied.Finally,a one-dimensional annular defective photonic crystal is proposed.Based on the basic characteristics of the photonic crystal combined with the transfer matrix method and the optical resonance principle,the mathematical model of the structure is established,and the sensing mechanism is analyzed to simulate the resonant mode of the ring defective photonic crystal Field distribution.The Q value characteristics of the sensing structure are studied,and the parameters are optimized,and the sensitivity characteristics are analyzed.In order to improve the Q value and the sensitivity,a special ring photonic crystalone-dimensional ring air gate photonic crystal sensing structure is proposed.The mathematical model between the defect peak and the refractive index of the gas to be measured is established by the optical resonance principle.By adjusting the number of cycles of the ring air gate photonic crystal,the resolution of the structure is improved,and by selecting a certain sample to be tested,the sensitivity of the photonic crystal sensing structure in the ring defect state is analyzed.