Deep-ultraviolet Cherenkov radiation in all-normal-dispersion waveguide enabled by spatial-temporal dynamics

TL;DR

This paper demonstrates high-energy ultraviolet Cherenkov radiation in a gas-filled capillary by leveraging complex spatial-temporal dynamics in multi-mode waveguides, enabling new ultrafast light source applications.

Contribution

It introduces a novel scheme for generating ultraviolet Cherenkov radiation using multi-mode nonlinear dynamics in a gas-filled capillary, achieving high pulse energies and ultrashort durations.

Findings

High-energy ultraviolet Cherenkov radiation achieved with mJ-level pulses.

Spatial-temporal dynamics significantly alter dispersion landscape.

Generated pulses are few femtoseconds with 100 μJ energies.

Abstract

Nonlinear propagation of ultrashort pulses in multi-mode waveguides, featuring complex spatial-temporal dynamics, provides new degrees of freedom in the fields of nonlinear optics and ultrafast lasers. Here, we demonstrate a new scheme of ultraviolet Cherenkov (dispersive-wave) radiation in a gas-filled capillary with unprecedently-high pulse energy, enabled by spatial-temporal dynamics. We found that mJ-level, 40-fs pulses, launched into a large-core capillary filled with high-pressure noble gas, would experience self-phase-modulation and self-steepening effects in this normal-dispersion waveguide, leading to high-intensity shock wave generation and asymmetric spectral broadening. Spatial-temporal dynamics, stemming from strong nonlinear inter-mode coupling, causes spatial shrink and temporal deceleration of the pulse which dramatically alter the capillary dispersion landscape. As a result, a phase-matching point can be created in the ultraviolet, giving rise to the radiation of multi-mode dispersive waves with 100-{\mu}J-level pulse energies and few-fs pulse widths. Our findings inspire new insights into multi-mode nonlinear optics, and the demonstrated high-energy ultraviolet light source with broadband tunability and compact set-up configuration, may find a few applications in time-resolved spectroscopy, ultrafast electronics and femtosecond chemistry.