Phase-matched second-harmonic generation in vapor-grown GaP ribbon waveguides

Phase-matched second-harmonic generation has been achieved in twinned as-grown ribbon ’’whiskers’’ of GaP about 50 μm wide and of submicrometer thicknesses. These naturally occurring slab waveguides were pumped with a Nd : YAG laser at a wavelength of 1.064 μm, and the second-harmonic output was observed as greenlight at 0.532 μm wavelength. Experiments concerning the second-harmonic generation are described, and the results are related to those expected from the crystallography of, and the modal dispersion in, the slab-waveguide ribbons.