Numerical analysis of effective refractive index ultrasonic sensor based on Cantilever arm structure slot-based dual-micro-ring resonator

We propose a novel ultrasonic sensor structure composed of Cantilever arm structure slot dual-micro-ring resonators (DMRR). We present a theoretical analysis of transmission by using the coupled mode theory. The mode field distributions and sound pressure distributions of transmission spectrum are obtained from 3D simulations based on Comsol Multi-physics (COMSOL) method. Our ultrasonic sensor exhibits theoretical sensitivity as high as 1462.5mV/kPa, which is 22 times higher than that of the single slot-based micro-ring ultrasonic sensor. Our ultrasonic sensor offers higher sensitivity and a larger detection frequency range than conventional piezoelectric-based ultrasound transducer. The results show that the sensing characteristics of our system can be optimized through changing the position and the angle of sound field. Our ultrasonic sensor is with an area of 25?m × 60?m, the Q-factor can be approximately 1.54 × 103 with radius of 5?m. We detect an angular range of-90° to 90° and a minimum distance of 0.01?m. Finally, we calculate the Cantilever arm structure slot DMRR array ultrasonic sensor's optical performance. Our proposed design provides a promising candidate for a hydrophone.