SPATIAL, TEMPORAL, AND SPECTRAL EFFECTS AND CONVERSION EFFICIENCIES IN 2ND-HARMONIC GENERATION FROM MODE-LOCKED LASERS IN SURFACE-EMITTING GEOMETRY

We have theoretically investigated ultrafast surface-emitting second-h armonic (SH) generation from mode-locked laser pulses with arbitrary p ulse shapes. The spatial dependence of the SH energy density per pulse is almost the same as the temporal profile of the SH power emitted fr om the entire surface per waveguide width for a long waveguide. For a sine fundamental pulse, we have obtained, rich and unique, temporal, s patial, and spectral behavior of the second harmonic. We have found th at both the temporal and spectral profiles of the emitted second harmo nic depend on the location at the surface. These effects can be observ ed with lasers currently available, and used for auto correlation, in optical signal processing, optical communications, and practical frequ ency doubling of ultrafast optical pulses with an advantage of no broa dening of the SH pulse. We have compared these results with those for a Gaussian fundamental pulse. After introducing saturation intensity t o quantify the saturation regime, we have obtained quantitative expres sion on the second-harmonic intensity in terms of the pump and saturat ion intensities. (C) 1997 American Institute of Physics.