Supercontinuum Generation in Gases

Abstract

Supercontinua extending from the ultraviolet to the infrared are observed from high-pressure (1-40 atm) Ar, Kr, Xe, ${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, or C${\mathrm{O}}_{2}$ illuminated with 2-psec or 70-fsec, 0.6-\ensuremath{\mu}m pulses with an energy \ensuremath{\lesssim}500 \ensuremath{\mu}J. The blue spectral component is shown to display a nearly universal behavior for all gases and pulse durations. Although the maximum intensity of the focused, femtosecond pulse in an evacuated cell was \ensuremath{\sim}${10}^{13}$ W/${\mathrm{cm}}^{2}$, continuum generation was only observed with the femtosecond pulse when the threshold for self-focusing was exceeded.