# Generation of ultra broadband coherent supercontinuum in tapered and dispersion managed silicon nanophotonic waveguides

## TL;DR

This paper demonstrates the design of tapered and dispersion managed silicon nanophotonic waveguides using genetic algorithms to generate ultra broadband, highly coherent supercontinuum spectra spanning over an octave, outperforming fixed-width waveguides.

## Contribution

It introduces a novel approach combining dispersion management and genetic algorithms to optimize supercontinuum generation in silicon nanophotonic waveguides.

## Key findings

- Supercontinuum spans over 1.14 and 1.25 octaves for DM and tapered waveguides.
- DM waveguides produce broader, flatter supercontinuum spectra.
- High coherence is maintained across the generated supercontinuum.

## Abstract

Tapered and dispersion managed (DM) silicon nanophotonic waveguides are investigated for the generation of optimal ultra broadband supercontinuum (SC). DM waveguides are structures showing a longitudinally dependent group velocity dispersion that results from the variation of the waveguide width with the propagation distance. For the generation of optimal SC, a genetic algorithm has been used to find the best dispersion map. This allows for the generation of highly coherent supercontinuums that span over 1.14 octaves from 1300 nm to 2860 nm and 1.25 octaves from 1200 nm to 2870 nm at -20 dB level for the tapered and DM waveguides respectively, 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.