Phase-matched second-harmonic generation in GaAs optical waveguides by focused laser beams

Using a tunable parametric oscillator operating near 2 μm, we have observed second-harmonic generation in a GaAs double-heterostructure waveguide in the region of phase matching. The harmonic intensity is strongly peaked when the guide propagation constants of the TE (m=0) fundamental and TM (m=2) harmonic are equal. Away from phase matching, the characteristic effects of strong focusing in the plane of the guide are observed. These are the one-dimensional analogs of the harmonic generation effects observed using two-dimensional focused laser beams.