Polarization tuning of third-harmonic generation by coupling of two types of quasi-phase-matched quadratic processes

The configurations for polarization tuning of third-harmonic generation by coupling of type-II and type-I quasi-phase-matched processes are proposed. In comparison with the conventional third-harmonic generation by coupling of two type-0 interactions, these configurations couple two cross-polarized fundamental components and exhibit an additional degree of freedom in controlling the harmonic conversion performance. The related analytical results are deduced systematically and a novel quasi-phase-matched splitting phenomenon is predicted. The polarization dependence of third-harmonic wave is performed experimentally, which coincides with the theory.