High-power ultra-flat supercontinuum generation in molecular-gas-filled anti-resonant fibres

We report on ultra-flat supercontinuum generation spanning from the deep ultraviolet to infrared based on anti-resonant hollow-core fibres filled with molecular gases. We utilise the comb-to-continuum supercontinuum technique which initially establishes a vibrational frequency comb and then merges the comb lines to form a continuous flat spectrum. We demonstrate high-power scalability, achieving spectral power densities reaching up to 10 mW/nm in the ultraviolet-visible spectral region at repetition rates exceeding 1 MHz. We have investigated many different molecular gases, pump pulse parameters (duration, wavelength) and fibre structures, and will report on optimised routes to ultimate supercontinuum performance.