One of the most important drawbacks of popular LiNbO₃ crystal is its susceptibility to photorefractive damage (optically induced change of refractive index, usually under exposure with blue or green CW light). The usual way to eliminate this effect is to keep LN crystals at elevated temperatures (400K or more). Another way to prevent photorefractive damage is MgO-doping (usually at levels of around 5 mol% for congruent LN). What is good is that such MgO-doped congruent LiNbO₃ crystals have a much lower coercive field value than undoped LN crystals.Recently, it was shown that stoichiometric LiNbO3 crystals, doped with only 1 mol% MgO, possess higher photorefractive damage threshold than 5 mol% MgO-doped congruent LN samples.

MgO:LiNbO₃ – A kind of nonlinear crystal optimize the performance of LiNbO₃

Pure LiNb0₃ (LN) is a good candidate for various optical devices, but has a major disadvantage due to its low threshold optical damage. MgO-doped LN(congruent compositions) is one of the possible solutions to deal with this problem. MgO doping has played an important role in LN and shown an increased threshold laser beam strength by 100 times. An interesting point is that every physical property of MgO-doped LN (e.g. transition temperature, activation energy, optical band , optical absorption spectra, shift of OH- vibration frequency, density, and electric activation energy based on our previous measurements4) has threshold composition at just above 5 mole% of MgO concentration.