Supercontinuum generation in a methane-filled hollow-core antiresonant fiber.

We report the generation of a multi-octave supercontinuum spanning from 350 nm to 1700 nm with exceptional spectral flatness and high conversion efficiency to both visible and near-infrared regions, by pumping a methane-filled hollow-core antiresonant fiber with 1030 nm laser pulses. The dynamics exhibited signs of both modulational instability (MI) and stimulated Raman scattering (SRS). Fiber lengths ranging from 15 cm to 200 cm were investigated along with gas pressures up to 50 bar and pump pulse durations from 220 fs up to 10 ps.