Sensing performance of dual-scale phoxonic crystals based on defect states

Abstract

A dual-scale phoxonic crystal sensing structure based on defect states is designed, and its acousto-optical sensing performance is numerically analyzed via the finite element method. First, the lattice parameters are optimized such that simultaneous photonic and phononic bandgap characteristics are exhibited by the structure within a specific frequency range, and efficient localization of acousto-optic energy is realized via defect states. It is revealed from the analysis of the acoustic and optical transmission spectrum that when the defect cavity is filled with solutions of 1-propanol, sodium chloride, and glucose at different concentrations, the resonant wavelength and frequency are regularly shifted in accordance with the changes in the refractive index and sound velocity of the solutions. It is indicated by the simulation results that a maximum optical sensitivity of 1036.83 nm/RIU (glucose solution) and a maximum acoustic sensitivity of 1.183 MHz/(m·s⁻¹) (sodium chloride solution) are achieved by the sensor, along with excellent quality factor and figure of merit performance. Potential deviations in the fabrication of the sensor structure are taken into account, and the robustness of the sensor within a certain deviation range is verified by introducing random displacement. The accuracy and stability of solution concentration measurements are significantly enhanced by this structure through the synergistic detection of acoustic and optical modes, with a high-precision detection solution provided for the field of biochemical sensing.