High-Power Ultra-Flat Supercontinuum Generation by Pumping Molecular Gas-Filled Hollow-Core Fibres in the Green

Supercontinuum generation in optical fibres is a well-established route towards broadband white-light sources with high spatial coherence and brightness, as required for a variety of applications in science and industry. The use of gas-filled hollow-core anti-resonant fibres [1], allows for tight confinement of both laser pulses and gas over long interaction lengths, with broadband guidance, enabling supercontinuum generation with extreme bandwidth [2]–[4]. Access to such supercontinua has been mainly achieved by pumping in the anomalous dispersion region and driving the electronic nonlinear response (optical Kerr effect) of gases, leading to modulational instability [2] and soliton effects [3], [4]. However, the former produces spectra with low temporal coherence, while the latter require very short pump pulses (few or tens of femtoseconds). Meanwhile, pumping in the normal dispersion region can result in limited spectral broadening through self-phase modulation.