Electromagnetic Cascade Sensor Based On Two-dimensional Photonic Crystal

With the development of information technology,the electromagnetic environment is becoming more and more complex,and the detection of the electromagnetic environment is of great significance to ensure the normal operation of the equipment.The optical method has the characteristics of anti-electromagnetic interference,and gradually replaces the electrical method and is used in electromagnetic sensing.As a new type of microstructure,photonic crystal has many advantages such as flexible design,small size and easy integration.In this paper,an electromagnetic cascade sensing structure based on two-dimensional photonic crystal microcavity is designed,which can realize the simultaneous detection of voltage and magnetic field,and provide a novel and convenient method of electromagnetic sensing.In this paper,the relationship between the sensitivity S and the quality factor of the side cavity coupled sensor structure H0 cavity and the improved H1 cavity and the characteristic parameters of the sensor structure is analyzed by using the plane wave expansion method and the finite-difference time-domain method with the help of Rsoft and Lumerical-FDTD simulation software.The structural parameters have been optimized.When the moving distance d0=0.06a of H0 cavity and the number of air holes N=4,the optimal structure is obtained.The sensing structure achieves the sensitivity of 210 nm/RIU and the quality factor reaches 3389.When the number of air holes N=7 and the radius of the air hole r1=0.24a,the sensitivity of the improved H1 cavity up to 200nm/RIU is achieved and the quality factor can reach 4207.Based on the above discussion,a voltage and magnetic field cascade sensing structure based on a two-dimensional photonic crystal is proposed,which can be used for voltage and magnetic field detection.The simulation and numerical analysis of the voltage and magnetic field cascade sensing structure are carried out and their parameters are optimized.The two-dimensional photonic crystal with lattice constant a=420nm,and air hole radius r=0.34a=142.8nm is finally optimized.When the moving distance of the air hole in the H0 cavity d₀=0.08a=33.6nm and the radius of the air hole in the H1 cavity r₁=0.20a=84nm,the voltage sensitivity of S_V=1.86nm/V in the range of14-50V,and a magnetic field sensitivity of S_m=13.06nm/m T in the range of 10-40m T of the sensor structure are obtained.In addition,the two pairs of sensor microcavities are independent of each other and have a good linear relationship in the corresponding measurement regions.The two-dimensional photonic crystal electromagnetic cascade sensing structure designed in this paper can not only solve the detection of voltage and magnetic field within a certain range,but also can be used in the integration of other multi-parameter photonic crystal sensing structures by changing the filling material.