摘要： In this study, we investigated the temperature dependence of cascaded parametric generations in nonlinear photonic crystals based on 2D periodically poled LiTaO3 (2D-PPLT) of square lattice structure. After establishing simultaneous multi-groups of frequency conversion from optical parametric generation (OPG) [1], it was found that the interaction of the signal ((cid:79)s), the idler ((cid:79)i) and the pump can further lead to several cascaded nonlinear processes such as SHG, SFG and DFG. The latter suggest existence of what can be called “magic” crossing points when mapping the nonlinear interactions vs temperature. We used a square lattice of 2D-PPLT with a period of 8.52μm and a filling factor of 38%. The crystal length was 2cm with a thickness of 0.5mm and pumped with a pulse 532nm green laser with a peak power of 80kW and a pulse width of 0.5ns. The measured spectra of the cascaded frequency conversion processes reveal 10 wavelength peaks at 393nm, 402nm,518nm, 532nm, 548nm, 787nm, 820nm, 1518nm, 1576nm and 1642nm at a crystal temperature of T= 110°C. More importantly, when the parametrically generated wavelengths were mapped as a function of the sample temperature (Fig. 1.a), an interesting phenomenon was observed at T = 64°C where four groups of wavelengths crossing at (cid:79) = 399nm ((cid:95)1(cid:178)), 532nm ((cid:95)2(cid:178)), 798nm ((cid:95)3(cid:178)), and 1596nm ((cid:95)4(cid:178)) concurred. By changing the crystal temperature, it would be possible to switch the involved nonlinear optical processes from degenerated to non- degenerated states. In addition to that, it implied a novel approach to generate entangled photons with controlled spectral features by parametric down conversion in a 2D nonlinear crystal [2]. We, then, took advantage of the Sellmeier equation for the crystal refractive index to evaluate the temperature effect on the QPM-parametric processes. Our study indicates that it is essential to carefully exert the parameters of Sellmeier equation reported in literature. Little changes of Sellmerier coefficients might induce an important misunderstanding of experimental data as well as erroneous design of efficient QPM frequency-conversion devices. The weight of this effect is more important when considering cascaded nonlinear interactions.