Temporal Characterization of Sub-3-fs, µJ-level Deep UV Pulses Generated by Resonant Dispersive Wave Emission

Abstract

The generation of few-femtoseconds laser pulses in the Deep Ultraviolet (DUV) spectral region (200-300 nm) is crucial for the investigation of ultrafast electronic dynamics in several classes of molecules. As prominent examples, both DNA nucleobases [1], as well as donor-acceptor systems, relevant for optoelectronic applications, readily absorb in this spectral range. In this context, Resonant Dispersive Wave (RDW) emission in gas-filled Hollow Core Fibers (HCF) is a novel and efficient way to generate µJ-level DUV few-fs pulses, continuously tuneable with gas pressure [2], with a consequent advantage in the proper matching of specific molecular excitations. The ultrashort time duration of such pulses is crucial for their application in high temporal resolution pump-probe spectroscopy experiments, but their large bandwidth in a notoriously challenging spectral region also renders their temporal characterization particularly demanding. Here, we report on the direct temporal characterization of few-cycle DUV pulses generated by RDW emission in a Neon-filled HCF, demonstrating near transform-limited pulses in the DUV.