Second-harmonic generation in Bragg-resonant quasi-phase-matched periodically segmented waveguides.

Second-harmonic generation in Bragg-resonant quasi-phase-matched periodically segmented waveguides is studied experimentally and theoretically. At resonance, a deep spectral valley appears in the quasi-phase-matching curve. Nevertheless, in practice, the conversion efficiency is significant, in spite of this effect, because of reduced reflections, especially at 2omega. The mechanism behind this reduction seems to be small random variation in the location and shape of the domain boundaries.