High-Sensitivity Refractive Index Sensing Based on Fano Resonances in a Photonic Crystal Cavity-Coupled Microring Resonator

Aiming for high-sensitivity refractive index biosensing, we investigate Fano resonance in a one-dimensional photonic crystal cavity-coupled microring resonator (PCMRR) on a silicon chip. Calculated results show that utilizing the asymmetric line shape of the Fano resonance, the detection limit can be reduced by a factor of 5 and the intensity detection sensitivity of PCMRR can be increased by a factor of 5 compared with a regular silicon-on-insulator, reaching the values of ~7.2 × 10
^-4
RIU and ~1.76 × 10
⁴
dB/RIU, respectively. Owing to its simplicity, compact footprint, and excellent performances, our device would be a promising candidate for optical label-free sensing applications.