Design And Performance Analysis Of Dual-Parameter Sensors Based On Photonic Crystal Fano Resonators

Photonic crystals generally refer to materials made of dielectrics with different refractive indices that are periodically arranged in accordance with a certain law.Photonic crystals can be divided into one-dimensional photonic crystals,two-dimensional photonic crystals,and three-dimensional photonic crystals according to the direction in which the refractive index is periodically arranged.The periodic arrangement of the refractive index makes the photonic crystal possess the photonic bandgap characteristic,and the light in the photonic bandgap cannot pass through the photonic crystal structure.By the photonic band gap,photonic crystals are widely used in the design and manufacture of optical devices,such as sensors,optical switches,filters,and light sources.Among them,photonic crystal sensors have the advantages of small structure size,small mode volume,easy integration and reuse,etc.,and have been widely used in various fields of sensing research in recent years.With the complication of sensor application scenarios in recent years,the improvement of sensor performance and the simultaneous sensing of multiple parameters have become difficult problems to be overcome in current sensor research.In this thesis,by coupling continuous light mode and local light mode,the Fano resonance line transmission is obtained,which further improves the detection accuracy of the photonic crystal sensor and reduces the structure size.The sensor structure studied in this thesis is based on one-dimensional photonic crystal nanobeam resonator structure and two-dimensional photonic crystal flat plate structure.The main contents of the thesis include:First,this paper analyzes the characteristics of photonic crystal sensing and Fano resonance,and studies the solution conditions for simultaneous detection of temperature and refractive index.Photonic crystal sensing mainly uses the photonic bandgap characteristics.By designing point defect and line defect structures in a photonic crystal,a resonant mode is designed.The resonant mode is used to sense changes in the environment.Fano resonance is composed of discrete and continuous states(or narrow and wide discrete states).After coupling,the full width at half maximum of the resonance peak will be further reduced based on the original narrow discrete state,thereby improving the sensing performance.Simultaneous two-parameter sensing requires a sensing matrix with a determinant that is not 0.The elements in the matrix are the sensitivities.The amount of change can be obtained by inverting the matrix and calculating the phase shift with the resonance peak.Second,the thesis studies the dual-parameter sensing application of Fano resonance in one-dimensional photonic crystal nanobeam resonator.Three structures are designed:single-cavity dual-mode one-dimensional photonic crystal nanobeam resonator sensor;dual-cavity dual-mode one-dimensional photonic crystal nanobeam resonator sensor and three-cavity dual-mode one-dimensional photonic crystal nanobeam resonator sensor.In the research of single-cavity dual-mode sensors,this paper introduces the design method of nanobeam resonators,studies the various sensor performance indicators of the structure,and verifies the simultaneous transmission of refractive index and temperature.Afterwards,this paper analyzes the structural problems and proposes corresponding solutions.To solve the problems of single-cavity dual-mode sensors,this thesis designs dual-cavity dual-mode sensors and three-cavity dual-mode sensors.In the research of the dual-cavity dual-mode sensor,this paper simplifies the design,analyzes the sensing performance,and verifies the feasibility of simultaneous sensing of refractive index and temperature.Compared with the single-cavity dual-mode sensor,the structural design of the dual-cavity dual-mode sensor is simplified and the sensing performance is improved.In the study of the three-cavity dual-mode sensor,this paper models the"three-cavity coupling" model and derives the transmission formula of the structure.To pursue better sensing performance,it is further optimized.The design of the resonant cavity has verified the feasibility of simultaneous sensing of dual parameters of refractive index and temperature.Compared with single-cavity dual-mode sensors,the sensing performance of three-cavity dual-mode sensors and the accuracy of simultaneous detection have been improved.Third,this paper studies the application of Fano resonance in two-dimensional photonic crystal board sensors.In the case of a normal incident light source,a single-plate two-dimensional photonic crystal flat plate structure based on Fano resonance and a two-plate two-dimensional photon crystal flat plate structure based on Fano resonance are designed.In the study of the single-plate two-dimensional photonic crystal flat plate structure,this paper designs and optimizes the single-plate structure,analyzes the relationship between the structure sensing performance and the structure parameters,and verifies the feasibility of simultaneous sensing of two parameters of refractive index and temperature sensitivities.In the study of the two-plate two-dimensional photonic crystal flat plate structure,the two-parameter sensing parameters are adjusted to the refractive index and molecular size of the object to be detected,and the detection purpose is to initially determine the molecular type of the object to be detected.During the research process,the double-plate structure was designed and optimized,and the three resonance peaks were used in different situations to detect small molecules.The molecular size of the substance to be detected can be distinguished,and the refraction of the substance measured by the intermediate resonance peak.The rate can be used to determine the type of molecule.The one-dimensional photonic crystal nanobeam resonator dual-parameter sensor and two-dimensional photonic crystal flat-plate sensor designed in this paper realize the simultaneous sensing of the refractive index and temperature in a liquid environment.These five sensors provide research ideas for the design of biochemical sensors in liquid environments,and provide the basis for the research of on-chip labelless detection systems.