Coherent, directional supercontinuum via cascaded dispersive wave generation

TL;DR

This paper introduces a new method for generating a coherent, directional supercontinuum using cascaded dispersive waves in silicon nitride waveguides, promising a stable, high-power, low-noise light source for spectroscopy.

Contribution

The paper presents a novel cascaded dispersive wave technique in normal dispersion regime to produce highly coherent, unidirectional supercontinuum spectra in integrated photonic waveguides.

Findings

Successful experimental demonstration in silicon nitride waveguides

High coherence confirmed via carrier-envelope-offset frequency detection

Potential for stable, high-power supercontinuum sources for spectroscopy

Abstract

We demonstrate a novel approach to producing coherent, directional supercontinuum via cascaded dispersive wave generation. By pumping in the normal group-velocity dispersion regime, pulse compression of the first dispersive wave results in the generation of a second dispersive wave, resulting in an octave-spanning supercontinuum generated primarily to one side of the pump spectrum. We theoretically investigate the dynamics and show that the generated spectrum is highly coherent. We experimentally confirm this dynamical behavior and the coherence properties in silicon nitride waveguides by performing direct detection of the carrier-envelope-offset frequency of our femtosecond pump source using an f-2f interferometer. Our technique offers a path towards a stabilized, high-power, integrated supercontinuum source with low noise and high coherence, with applications including direct comb spectroscopy.