Supercontinuum generation in silicon Bragg grating waveguide

Abstract

Supercontinuum generation is an extensively studied and arguably the most important and all-encompassing nonlinear phenomenon. Yet, we do not have a good control over all the signals generated in this process. Usually, a large part of an octave spanning spectrum has an orders of magnitude weaker signal than the peak to be useful for any application. In this work, we show strong signal generation within a supercontinuum generated in a complementary metal-oxide-semiconductor compatible silicon Bragg grating waveguide. We show up to 23 dB of signal enhancement over a 10 nm full-width-at-half-maximum bandwidth at the Bragg resonance in the telecom window. Additionally, the grating is made by depositing charge carriers periodically, thus avoiding any dimensional change in the waveguide, and it can allow other functionalities offered by the induced electric field, such as second harmonic generation and free carrier sweeping. We believe this work opens up an avenue for research in nonlinear integrated photonics and signal enhancement in the supercontinuum by the Bragg effect (whether created through grating formation with dimensional variation in insulators and/or periodic charge carrier doping in semiconductors).