Vacuum-UV to IR supercontinuum in hydrogen-filled photonic crystal fiber

TL;DR

This paper demonstrates the generation of a broad supercontinuum from vacuum ultraviolet to infrared in hydrogen-filled kagome-style hollow-core photonic crystal fiber, enabling new applications in biology, chemistry, and physics.

Contribution

It reports the first development of a bright, ultrabroad supercontinuum spanning 124 nm to over 1200 nm in hydrogen-filled kagome-PCF, including the VUV range.

Findings

Supercontinuum spans from 124 nm to beyond 1200 nm.

Efficient generation of VUV dispersive wave at 182 nm.

Kagome-PCF guides well in the VUV range.

Abstract

Although supercontinuum sources are readily available for the visible and near infrared, and recently also for the mid-IR, many areas of biology, chemistry and physics would benefit greatly from the availability of compact, stable and spectrally bright deep ultraviolet (DUV) and vacuum ultraviolet (VUV) supercontinuum sources. Such sources have however not yet been developed. Here we report the generation of a bright supercontinuum, spanning more than three octaves from 124 nm to beyond 1200 nm, in hydrogen-filled kagom\'e-style hollow-core photonic crystal fiber (kagom\'e-PCF). Few-{\mu}J, 30 fs pump pulses at wavelength 805 nm are launched into the fiber, where they undergo self-compression via the Raman-enhanced Kerr effect. Modeling indicates that before reaching a minimum sub-cycle pulse duration of ~1 fs, much less than one period of molecular vibration (8 fs), nonlinear reshaping of the pulse envelope, accentuated by self-steepening and shock formation, creates an ultrashort feature that causes impulsive excitation of long-lived coherent molecular vibrations. These phase-modulate a strong VUV dispersive wave (at 182 nm or 6.8 eV) on the trailing edge of the pulse, further broadening the spectrum into the VUV. The results also show for the first time that kagom\'e-PCF guides well in the VUV.