Potassium dideuterium phosphate
Deuterated potassium dihydrogen phosphate or DKDP single crystals are widely used in non-linear optics as the second, third and fourth harmonic generators for and lasers. They are also found in electro-optical applications as Q-switches for,, Alexandrite and Ti-sapphire lasers, as well as for Pockels cells.
DKDP is closely related to monopotassium phosphate or KDP or KH2PO4. Replacement of hydrogen by deuterium in DKDP lowers the frequency of O-H vibrations and their overtones. Absorption of light by those overtones is detrimental for the infrared lasers, which DKDP and KDP crystals are used for. Consequently, despite higher cost, DKDP is more popular than KDP.
DKDP crystals are grown by a water-solution method at usual level of deuteration >98%.
