Harnessing Sub-Wavelength and Symmetry Engineering for the Implementation of High-Performance Silicon Bragg Grating Filters

Bragg filters stand as a key building blocks of the silicon-on-insulator (SOI) photonics platform, allowing the implementation of advanced on-chip signal manipulation. However, achieving narrowband Bragg filters with large rejection levels is often hindered by fabrication constraints and imperfections. Here, we present a new generation of high-performance Bragg filters that exploit subwavelength and symmetry engineering to overcome bandwidth-rejection trade-off in state-of-the-art implementations. We experimentally show flexible control over the width and depth of the Bragg resonance. These results pave the way for the implementation of high-performance on-chip pump-rejection filters with a great potential for Si-based quantum photonic circuits.