Modeling and design of a coupled PhC slab sensor for simultaneous detection of refractive index and temperature with strong anti-interference ability

Abstract

In this paper, we propose a coupled-double-photonic-crystal-slab (CDPCS) sensor for simultaneously detecting refractive index (RI) and temperature (T) with high accuracy and strong anti-interference ability, using transverse magnetic-like (TM-like) mode and transverse electric-like (TE-like) mode. Based on the temporal coupled-mode theory, the theoretical model of the structure is established and the transmission formula is derived. The agreement between the theoretical and the simulated transmission spectra is proved. In order to achieve both high quality (Q)-factor and high modulation depth, the structure is optimized by adjusting the geometric parameters. The Q-factors of both TM-like mode and TE-like mode reach a magnitude order of 105. For the dual-parameter sensing, high RI sensitivities of 960 nm/RIU and 210 nm/RIU, and T sensitivities of -66.5 pm/K and 50.75 pm/K, are obtained for TM-like mode and TE-like mode, respectively. The relative deviations of RI and T sensing are as low as 0.6% and 1.0%, respectively, indicating high detection accuracy. Even considering the influence of external interference, the sensor can effectively resist external interference. The proposed CDPCS sensor has remarkable performance improvements in sensitivity, Q-factor, detection accuracy, and anti-interference ability. This study shows great potential in on-chip sensing and multi-parameter detection.