Generation of a VUV-to-visible Raman frequency comb in hydrogen-filled kagom\'e photonic crystal fiber

TL;DR

This paper demonstrates a hydrogen-filled kagomé photonic crystal fiber that generates a broad Raman frequency comb from vacuum ultraviolet to visible light, enabling tunable UV sources for spectroscopy and biomedical applications.

Contribution

It reports the first generation of a purely vibrational Raman comb spanning from 184 nm to 478 nm in a hydrogen-filled kagomé fiber pumped at 266 nm, highlighting pressure-tunable dispersion effects.

Findings

Generated Raman comb from 184 nm to 478 nm

Higher-order anti-Stokes bands in higher-order fiber modes

Enhanced Raman gain in the ultraviolet

Abstract

We report the generation of a purely vibrational Raman comb, extending from the vacuum ultraviolet (184 nm) to the visible (478 nm), in hydrogen-filled kagom\'e-style photonic crystal fiber pumped at 266 nm. Stimulated Raman scattering and molecular modulation processes are enhanced by higher Raman gain in the ultraviolet. Owing to the pressure-tunable normal dispersion landscape of the fiber-gas system in the ultraviolet, higher-order anti-Stokes bands are generated preferentially in higher-order fiber modes. The results pave the way towards tunable fiber-based sources of deep- and vacuum ultraviolet light for applications in, e.g., spectroscopy and biomedicine.