Stimulated light scattering and optical parametric oscillation in noncollinear wave interactions in the xy plane of a KTP crystal excited by the second harmonic of an Nd:YAG laser

The characteristic features of stimulated light scattering and optical parametric oscillation in noncollinear wave interactions, excited by radiation with the wavelength λ_p = 532.1 nm in the xy plane of a KTP crystal, were studied experimentally. Stimulated scattering on polaritons was observed on excitation of the KTP crystal, by an ordinary (o) beam. Radiation in the far IR was generated within the crystal at the wavelength λ_r ≈ 52 μm and the frequency ν_r = 192.3 cm^–1. The generation and amplification of Stokes radiation with λ_s1 = 537.6 nm were achieved (frequency shift ~ 192.3 cm^–1 ) with an efficiency of ~ 18% at 22 °C. It was established from the threshold oscillation characteristics that the stimulated scattering gain was ~ 30 cm GW^–1 . Simultaneous parametric generation of two collinear signal waves with λ_so = 1054.5 nm and λ_se = 1069.2 nm and two noncollinear idler waves with λ_ie = 1074.1 nm and λ_io = 1059.3 nm was observed on excitation by the extraordinary (e) beam. Addition of the frequencies of two collinear signal waves in the KTP crystal led to the appearance of anti-Stokes radiation with λ_as = 530.9 nm.