On-Chip Demodulation Approach Based on Microring Resonator for Fiber-Optic Vernier Effect Sensing

We present a chip-scale integrated demodulation approach based on a microring resonator (MRR) for fiber-optic interferometric sensors. The system consists of a temperature sensor based on a Sagnac interferometer (SI) and an on-chip microring filter. The spectral superposition of the two devices generates a Vernier effect, resulting in an approximately eightfold increase in the sensitivity of the SI temperature sensor. In addition to theoretical simulations of the sensitivity amplification principle of the proposed demodulation method, details of its laboratory evaluation are also provided. Furthermore, integrating a suitable filter into the system enables intensity demodulation of the SI sensors. This microdemodulation approach can be extended to other types of interferometric sensors.