Investigation of multiconversion processes in periodically poled LiNbO3-based optical parametric oscillators

The multiconversion processes in optical parametric oscillators based on periodically poled LiNbO3 are investigated. Interpretations based on simultaneous quasiand birefringent phase matching are presented. Three parametric and three harmonic generation processes in a multigrating periodically poled LiNbO3 crystal were observed. Two of the parametric processes and two of the harmonics were quasi-phase matched, and the other conversion processes were phase matched through birefringence in the crystal. The primary parametric process ((omega)p - (omega)s + (omega)i) was obtained through first-order quasi-phase matching. The other quasiphase-matched processes occurred within higher orders. The existence of even-order quasi-phase matching in the crystal is due to other than a 50% duty-cycle grating periods. The tuning range for each of the generated waves is obtained and compared with theoretical fittings.