Integrated Optical Chemical Sensor Based on an SOI Ring Resonator Using Phase-Interrogation

A phase-interrogation approach for the bulk refractive index sensing based on a silicon-on-insulator (SOI) ring resonator is introduced. The rapid phase variation around the resonance of the ring resonator is interrogated, and a single-sideband generation and coherent detection technology is adopted for the phase measurement. In the proposed approach, most of the intensity noise can be shielded, which leads to an ultra-stable reading for the phase signals. A sensitivity of 6 × 10 3 rad/RIU and a detection limit of 2.5 × 10 -6 RIU are demonstrated.