  Ultrafast supercontinuum generation in gas-filled waveguides is one enabling
technology for many intriguing application ranging from attosecond metrology
towards biophotonics, with the amount of spectral broadening crucially
depending on the pulse dispersion of the propagating mode. Here we show that
the structural resonances in gas-filled anti-resonant hollow core optical fiber
provide an additional degree of freedom in dispersion engineering, allowing for
the generation of more than three octaves of broadband light ranging deep UV
wavelength towards the near infrared.Our observation relies on the introduction
of a geometric-induced resonance in the spectral vicinity of the pump laser
outperforming the gas dispersion, thus yielding a dispersion being independent
of core size, which is highly relevant for scaling input powers.Using a Krypton
filled fiber we observe spectral broadening from 200 nm towards 1.7 \mu m at an
output energy of about 23 \mu J within a single mode across the entire spectral
bandwidth. Simulations show that the efficient frequency generation results
from a new physical effect the soliton explosion originating from the strongly
non-adiabatic mode dispersion profile.This effect alongside with the dispersion
tuning capability of the fiber will enable compact ultrabroadband high energy
sources spanning from the UV to the mid-infrared spectral range.

Optics