Solving the puzzle of supercontinuum generation

Summary form only given. Supercontinuum generation (SCG) is the explosive increase in bandwidth suffered by an intense laser pulse propagating through a medium. Although the details vary, it is a universal phenomenon observed in gasses, liquids, and solids using a wide range of pump pulse energies and widths. It arises due to the complex interplay of the Kerr effect, Raman scattering, ionization, and dispersion. Describing even qualitative features in the SCG spectrum generally requires treating the breakdown of the slowly varying envelope approximation and the interplay between the pulse's spatial and temporal evolution. Yet the effort to understand SCG is worthwhile, since there seems to be little limit to its application as a source of tunable short pulse radiation, in communications, in precision measurement, and even in clinical diagnostics. There have been a number of sophisticated treatments of SCG recently that have greatly raised the standard for the quantitative treatment of this phenomenon. We have introduced a novel measurement technique, the spectrally-resolved double pump, that allows us to settle a number of issues important to the understanding of SCG.