非線形光学結晶による可変波長4光子パラメトリック発光

抄録

Tunable four-photon parametric fluorescence, which is valuable for investigating material nonlinearities and parametric devices, was studied theoretically and experimentally. Theoretical analysis leads to the conclusion that the emitted power depends directly on the focusing of the pumping beam, unlike the process of the three-photon parametric fluorescence which is independent of this beam focusing. The calculation of the phase-matching conditions for nonlinear crystals such as KDP, ADP, TiO₂ and CdS shows that collinear phase-matching can be realized over the visible region using a ruby laser for pumping. Tunable emission was observed experimentally in the visible range from 4200 Å to 5300 Å with KDP, ADP and TiO₂ crystals pumped by a Q-switched ruby laser. The magnitude of the third-order nonlinearities for these crystals were also evaluated experimentally, and compared with previous data derived by the three-wave mixing and the third harmonic generation methods.