Spectral broadening in hollow-core fibers as a function of input chirp

Summary form only given. Gas filled hollow core fibers are an ideal nonlinear-optical medium for the spectral broadening of high energy ultrashort pulses, and these fibers have been used to compress 20 fs sub-mJ pulses down to /spl sim/5 fs. The spectral broadening of laser pulses is due to the self-phase modulation (SPM) in the gas that fills the fiber. Since SPM induces a positive chirp to the pulse, the initial temporal phase of the input pulse should have an effect on the broadening. We demonstrated experimentally that output spectral width depends strongly on the chirp of the input pulse and can be used to optimize it.