Design and optimization of silicon concentric dual-microring resonators for refractive index sensing

In this paper, a silicon concentric dual-microring resonator for refractive index sensing is designed. The influences of the mode effective index difference, extinction ratio (ER), and sensitivity on the homogeneous sensing of sucrose solutions are investigated by using 3-D finite-difference time-domain (FDTD) method. The geometry structures of the concentric dual-microring resonator are optimized to satisfy the desired sensing performance. Moreover, a refractive index sensor based on the designed concentric dual-microring resonator is proposed, which can realize the ER of 30 dB, sensitivity of 180 nm/refractive index units (RIU), and detection limit of 1.1×10−5 RIU. It is believed that the proposed refractive index sensor can find important application in the refractive index sensing.