Potassium Dihydrogen Phosphate (KDP) and Potassium Dideuterium Phosphate (DKDP ) are among the most widely-used commercial NLO materials, characterized by good UV transmission, high damage threshold, and high birefringence, though their NLO coefficients are relatively low. They are usually used for doubling, tripling and quadrupling of a Nd:YAG laser at the room temperature. In addition, they are also excellent electro-optic crystals with high electro-optic coefficients, widely used as electro-optical modulators, such as Q-switches, Pockels Cells, etc.

Notes: Because their polished surface easier moistens, however, the user is advised to provide a dry condition (<50%) and the sealed housing for preservation.