Crystals for nonlinear optics

A review is given of nonlinear optical properties of seven biaxial crystals: KB5, DKB5, LFM, Ba₂NaNb₅O₁₅, KTP, α-HIO₃, and KNbO₃. Typical applications of these crystals are listed. Formulas are given for the calculation of the phase-matching angles of biaxial crystals for the propagation of radiation in principal planes.