High-flux, ultraviolet-to-visible-tunable, ultrafast light source based on gas-filled capillary fibre system

Abstract

Abstract Ultrafast light sources with broadband wavelength tunability, as useful tools for studying ultrafast phenomena and light-matter interactions, have attracted extensive interests in recent several decades. High-performance ultrafast pulse generation with simultaneously high pulse repetition rate, high photon flux, and broad wavelength-tuning range covering deep ultraviolet to visible has, however, proven difficult to realize. Here, we demonstrate that through cascading two nonlinear pulse compression stages (one is based on a multi-pass-cell cavity and the other based on a 1-m length of hollow capillary fibre), high-repetition-rate pulses from an industrial-grade high-power picosecond laser can be efficiently compressed to ~15 fs durations, giving rise to an ultrahigh compression ratio of ~74. The generated few-cycle optical pulses, exhibiting excellent beam quality and stability, were used in our set-up to drive the high-efficiency dispersive-wave-emission process in another 1-m length of gas-filled capillary fibre, delivering few-cycle short-wavelength pulses with μJ-level pulse energy, 25 kHz/100 kHz pulse repetition rate, >1016 phs/s photon flux and continuous wavelength-tuning ability from 200 nm to 700 nm. The table-top ultrafast laser system, featuring broad wavelength coverage, may have many potential applications in advanced spectroscopy and ultrafast-optics experiments.