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Introduction 
Lithium niobate is a ferroelectric material suitable for a variety of applications. Its versatility is made possible by the excellent electro-optic, nonlinear, and piezoelectric properties of the intrinsic material. It is one of the most thoroughly characterized electro-optic materials, and crystal growing techniques consistently produce large crystals of high perfection.

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 thecrystal and the fact that the longer wavelength photons that are generated in the process are less energetic.

Physical and Chemical Properties:
Please view NLO crysals physical Properities.

The Sellmeier equations (l in µm ):
n_o²=4.9048+0.11768/(l ²-0.04750)-0.027169l ² 
ne²=4.5820+0.099169/(l ²-0.004443)-0.021950l ² 

Optical and Spectral Properties:
Please view NLO crysals optical and nonlinear optical Properities. 

the Fe:LiNbO3 and MgO:LiNbO3 crystals is available too. The MgO: LiNbO3 has similar effective nonlinear coefficients to pure LiNbO3. Its Sellmeier equations (for MgO dopant 7 mol%) are: 
n_o²=4.8762+0.11554/(l ²-0.04674)-0.033119l ² 
ne²=4.5469+0.094779/(l ²-0.04439)-0.026721l ²