Observation and characterization of broadband radiation from a mode-locked Nd: glass laser

Broadband continuum radiation on the order of one erg per 100 ${\mathrm{cm}}^{-1\mathrm{}}$ and extending several thousand angstroms outside the gain curve of a Nd: glass laser has been observed and theoretically analyzed to be consistent with an electronic phase modulation process brought about by an intensity-dependent nonlinear index of refraction in the active medium of the mode-locked laser. Possible sideband pulse powers may approach 1 MW for 100 ${\mathrm{cm}}^{-1\mathrm{}}$ linewidth. Temporal and spatial synchronization of the sideband and 1.06-μm laser pulses is verified and utilized when the pulses are optically mixed in a nonlinear ammonium dihydrogen phosphate crystal to extend the region of the intense ultrashort continuum to higher frequencies.