Generation of ultra-broadband coherent supercontinua in tapered and dispersion-managed silicon nanophotonic waveguides

The generation of an optimal ultra-broadband supercontinuum (SC) is numerically investigated in tapered and dispersion-managed (DM) silicon nanophotonic waveguides. DM waveguides are structures showing a longitudinally dependent group velocity dispersion that results from the variation of the waveguide width with the propagation distance. A genetic algorithm is used to find the best dispersion map. This allows for the generation of highly coherent supercontinuums that span over 1.14 octaves from 1300 to 2860 nm and 1.25 octaves from 1200 to 2870 nm at the -20 dB level for the tapered and DM waveguides for a 2 mu m, 200 fs and 6.4 pJ input pulse. The comparison of these two structures with the usually considered optimal fixed-width waveguide shows that the SC is broader and flatter in the more elaborated DM waveguide, while the high coherence is ensured by the varying dispersion. (c) 2017 Optical Society of America