Spectral Broadening and Temporal Compression of Ultrashort Pulses in a Gas Cell

Spectral broadening, also known as continuum generation, arising from the interaction of intense ultrashort laser pulses with nonlinear materials is a well known, highly exploited phenomenon.1 White light generated from focusing ultrashort pulses into transparent media or by the propagation of high intensity pulses through fiber is commonly used as a coherent broadband source for applications such as time-resolved spectroscopy2, seeding optical parametric amplifiers3,4, and optical coherence tomography5, just to name a few. The effect of spectral broadening can also be used for generating pulses significantly shorter than the original input pulse (i.e. pulse compression). Utilizing this technique for pulse compression was demonstrated by Ippen et al.6 for the compression of picosecond pulses down to the femtosecond time regime using a single mode fiber and a grating pair. Spectral broadening and the subsequent recompression of high intensity pulses in rare gases was demonstrated by Krausz and coworkers7, and has since become a proven technique for the generation of pulses as short as a few optical cycles (5.1 femtoseconds, FWHM)