Photonic crystal concentric dual-microring resonator for refractive index sensing

Abstract

A high-performance photonic crystal (PhC) concentric dual-microring resonator (PhCCDMRR) for refractive index sensing is proposed in this paper. It confines the energy into PhC air holes to enhance the light–matter interaction, and the increased modal area of the concentric rings improves the sensing sensitivity. The slow-light effect near the photonic bandgap results in a PhC waveguide with a maximum group index of 18.2. In the transmission spectrum, a high extinction ratio of 22 dB is achieved. This sensor obtains a refractive index (RI) sensitivity of 265 nm/RIU (RI unit) using sodium chloride solution as samples, which has promising applications in RI sensing.