The optimal vector phase matching conditions in biaxial crystalline materials determined by extreme surfaces method: the case of orthorhombic crystals

The optimal geometries of vector phase matching are determined for the cases of second harmonic, sum and difference frequency generation in a number of orthorhombic nonlinear optical crystals - KTP, KTA, KB5, KNbO3, LBO, CBO, LRB4. Extreme surface method was used to define wave vectors directions of highest possible generation efficiency. As it is shown, in a significant number of cases vector phase matching ensures higher efficiencies than the scalar one.