THz Generation From GaP Rod-Type Waveguides

Abstract—Terahertz (THz) generation was demonstrated from GaP rod-type waveguides via difference-frequency-mixing of near-infrared light using a collinear phase-matching condition. THz output peaks were observed, and appeared at frequencies corresponding to the fundamental and high-order waveguide modes. Interestingly, the position of the fundamental mode shifted to a higher frequency for a smaller waveguide cross-section, which is attributed to the waveguide confinement of the THz wave. The conversion efficiency was enhanced in the waveguide with a cross section of 200 m 160 m as compared to that in bulk GaP crystals. Index Terms—Collinear phase matching, GaP, optical wave-guide, phonon-polariton, terahertz (THz)-wave. I