Ultra-broadband supercontinuum generation in gas-filled photonic-crystal fibers: The epsilon-near-zero regime

TL;DR

This paper theoretically demonstrates that gas-filled hollow-core photonic crystal fibers can generate broadband supercontinuum light in the mid-infrared by exploiting the interplay of Kerr and photoionisation nonlinearities near the epsilon-near-zero regime.

Contribution

It introduces a novel approach to broadband supercontinuum generation using gas-filled fibers near epsilon-near-zero conditions, highlighting the role of photoionisation and Kerr effects.

Findings

Broadband supercontinuum achieved in the mid-infrared regime.

Enhanced nonlinear effects due to epsilon-near-zero conditions.

Multiple dispersive-wave emissions observed.

Abstract

In this Letter, we show theoretically that the nonlinear photoionisation process of a noble gas inside a hollow-core photonic crystal fibre can be exploited in obtaining broadband supercontinuum generation via pumping close to the mid-infrared regime. The interplay between the Kerr and photoionisation nonlinearities is strongly enhanced in this regime. Photoionisation continuously modifies the medium dispersion, in which the refractive index starts to significantly decrease and approach the epsilon-near-zero regime. Subsequently, the self-phase modulation induced by the Kerr effect is boosted because of the accompanied slow-light effect. As a result of this interplay, an output spectrum that comprises of a broadband light with multiple dispersive-wave emission is obtained.