Effect of induced optical inhomogeneity of the refractive index on second harmonic generation in lithium metaniobate crystals

A theoretical analysis is made of second harmonic generation allowing for the induced optical inhomogeneity of the refractive index in lithium metaniobate crystals. It is shown that an optimal nonzero mismatch of the vectors exists at which total conversion of the fundamental-frequency radiation into the second harmonic can be achieved. The characteristics of a frequency converter operating under phasematching conditions are given for comparison.