Supercontinuum generation in silicon Bragg grating waveguide.

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 orders of magnitude too much weaker signal than the peak to be useful for any application. In this work we show strong signal generation within a supercontinuum using a 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. Since the grating is made by depositing charge carriers periodically, thus avoiding any dimensional change in the waveguide, it can allow other functionalities offered by the induced electric field, such as second harmonic generation. The ease of grating fabrication, whether with dimensional variation or doping, makes such a device useful for enhancing signal strength at any desired frequencies with high precision within a supercontinuum independent of material platform. We believe this work opens a new avenue for supercontinuum enhancement on demand in integrated photonics.