Compression of megawatt femtosecond laser pulses using a large-mode-area all-silica photonic band-gap fiber

Energies and peak powers of ultrashort light pulses available directly from laser oscillators continue to grow, calling for compact and efficient pulse-compression solutions. In the megawatt range of peak powers, typical of a broad class of advanced laser systems, including fiber and thin-disk lasers, pulse compression becomes a challenging task, as this level of peak powers is too low for filamentation- or hollow-waveguide-assisted compression in the gas phase [1], but is too high for single-mode compression in conventional fibers. Large-mode area (LMA) photonic-crystal fibers (PCFs) [2] offer promising solutions to this problem, enabling compression of a megawatt short-pulse thin-disk [3, 4] and fiber-laser [5] output with no degradation of beam quality. For a large-core fiber, however, dispersion profile is typically dominated by material dispersion, with the range of fiber dispersion engineering being very limited.