Applications that use the large nonlinear d coefficient of LiNbO3 include optical parametric oscillaton, difference frequency mixing to generate tunable infrared wavelengths, and second harmonic generation. With a broad spectral transmission, which ranges from 0.4 μm to 5.0 μm with an OH- absorption at 2.87 μm, a large negative birefringence, and a large nonlinear coefficient, phasematching is an effective way to generate tunable wavelengths over a broad wavelength range.
Lithium niobate is particularly effective for second harmonic generation of low power laser diodes in the 1.3 to 1.55 μm range.
For infrared generation by difference frequency mixing, the peak power limit is considerably lower than for 1.064 μm, being about 40 MW/cm2Efficiencies for difference frequency mixing generally are smaller than shg efficicncies with KDP or BBO, which is due to the lower peak powers that can be tolerated by the crystal and the fact that the longer wavelength photons that are generated in the process are less energetic. |
