Two-parameter Optical Sensing Based on Multilayer Parity-time-symmetric Structure

Abstract

A two-parameter sensor that can detect the variation of temperature and refractive index is realized in a multilayer dielectric structure obeying parity-time (PT) symmetry. The sensor can operate near exceptional points (EPs), which have been shown to provide dramatic variations of their eigenvalues in response to small parameter changes. The optical sensing behavior is theoretically investigated based on the transfer matrix method. The results show that the sensor can work within the surrounding temperature (tp) ranging from 0 to 30℃, and the refractive index (ng) of incident medium ranging from 1.0 to 1.4. The detectable variation △ng of the sensor can reach 0.02. The sensitivity of ng and tp can reach 372496.53 RIU-1 and 249.18℃-1, respectively. Our structures show great promise in temperature monitoring in cold environment and identification of chemical gases or liquids.