An Optimized Integrated Optical Coupled Micro Ring Resonator for Low Pressure Sensing

In this work, a novel Integrated-optical serially coupled microring resonator-based mechanical pressure sensor is reported. Finite-Difference-Time-Domain (FDTD) approach is used to build, analyze, and optimize $5\mu \text{m}$ and $4\mu \text{m}$ microring resonators(MRs). These optimized MRs are used in the design and analysis of a serially coupled microring resonator (SCMR). The SCMR is used as a sensing element in the pressure sensor. To experience the maximum stress, the sensing element is integrated with the square-shaped mechanical diaphragm. The stress of this diaphragm is analyzed by Finite-Element-Method of COMSOL Multiphysics and the FDTD method of Ansys Lumerical simulation tool is used for the analysis of the field propagation through the SCMR. The Photo-elastic effect is the working principle of this device. The dimensions of this sensor are $25\times 25\mu \text{m}^{2}$ . A sensitivity of 0.34nm per 0.1 MPa, FSR of 94nm, and a Q-factor of 21514 are reported. The sensor can be used to measure the applied pressure range of 0 to 600 kPa. A microring resonator of radius $5\mu \text{m}$ is fabricated and characterized at an operating wavelength of 1550nm.