Research progress on spectral modulation and sensing applications of Bragg-grating-assisted microring resonators

Silicon-based integrated photonic platforms have become the core infrastructure for next-generation optical devices due to their CMOS compatibility, high integration density, and low cost. A Bragg grating is an optical device based on Bragg diffraction that achieves selective reflection or transmission at specific wavelengths through periodic modulation of the refractive index. As a key component in silicon photonics, the microring resonator features a simple structure and excellent resonant performance, typically exhibiting a Lorentzian-shaped comb spectrum. To overcome the limitations of standalone gratings or microring resonators regarding sensitivity, detection range, and spectral lineshape, and to enable flexible spectral modulation, this paper reviews research progress on Bragg grating-assisted microring resonators. We summarize studies on integrating Bragg gratings into ring and bus waveguides, respectively, and analyze their spectral regulation mechanisms. Emphasis is placed on the generation mechanisms of key spectral effects, such as the electromagnetically induced transparency (EIT)-like effect, Fano resonance, mode splitting, and side-mode suppression. The roles of these spectral regulation techniques in enhancing sensor performance are discussed, including achieving ultra-high sensitivity through lineshape modulation and overcoming free spectral range limitations via side-mode suppression. This work provides a systematic reference for designing and developing high-performance silicon-based integrated optical sensors.