  Supercontinuum (SC) generation based on ultrashort pulse compression
constitutes one of the most promising technologies towards an ultra-wide
bandwidth, high-brightness and spatially coherent light sources for
applications such as spectroscopy and microscopy. Here, multi-octave SC
generation in a gas-filled hollow-core antiresonant fiber (HC-ARF) is reported
spanning from 200 nm in the deep ultraviolet (DUV) to 4000 nm in the
mid-infrared (mid-IR). A measured average output power of 5 mW was obtained by
pumping at the center wavelength of the first anti-resonance transmission
window (2460 nm) with ~100 fs pulses and an injected pulse energy of ~7-8
{\mu}J. The mechanism behind the extreme spectral broadening relies upon
intense soliton-plasma nonlinear dynamics which leads to efficient soliton
self-compression and phase-matched dispersive wave (DW) emission in the DUV
region. The strongest DW is observed at 275 nm having an estimated pulse energy
of 1.42 {\mu}J, corresponding to 28.4 % of the total output energy.
Furthermore, the effect of changing the pump pulse energy and gas pressure on
the nonlinear dynamics and their direct impact on SC generation was
investigated. The current work paves a new way towards novel investigations of
gas-based ultrafast nonlinear optics in the emerging mid-IR spectral regime.
