Polarization Insensitivity Research of the Three-layer Silicon-based Symmetric Cascade Optical Sensor

Abstract

This paper presents a symmetric all-dielectric two-dimensional grating with high transmittance and high figure of merit (FOM) based on cylindrical nanoarrays as a liquid sensing structure with small volume and high sensitivity. The device is optimized using the finite element method to calculate the transmissivity under TE/TM polarization. When the incident angle is 4 degrees, the transmissivity of the grating is nearly 1 with a full width at half maximum of 0.0158 nm and a sensitivity of 256.196 nm/RIU. The FOM is 16214.937. The sensor characteristics of the incident angle on the device are analyzed, and the normalized electric field distribution indicates that the change of the incident angle has a significant modulation ability for the resonance energy distribution. The proposed sensor is independent of polarization state, easy to control and integrate, and has broad application prospects in fields such as liquid solution detection, ocean surveys, and position sensing.