A Powder Technique for the Evaluation of Nonlinear Optical Materials

An experimental technique using powders is described which permits the rapid classification of materials according to (a) magnitude of nonlinear optical coefficients relative to a crystalline quartz standard and (b) existence or absence of phase matching direction(s) for second-harmonic generation. Results are presented for a large number of inorganic and organic substances including single-crystal data on phase-matched second-harmonic generation in HIO3, KNbO3, PbTiO3, LiClO4·3H2O, and CO(NH2)2. Iodic acid (HIO3) has a nonlinear coefficient d14∼1.5×d31 LiNbO3. Since it is readily grown from water solution and does not exhibit optical damage effects, this material should be useful for nonlinear device applications.