Potassium dideuterium phosphate

Deuterated potassium dihydrogen phosphate (KD₂PO₄) or DKDP single crystals are widely used in non-linear optics as the second, third and fourth harmonic generators for Nd:YAG and Nd:YLF lasers. They are also found in electro-optical applications as Q-switches for Nd:YAG, Nd:YLF, Alexandrite and Ti-sapphire lasers, as well as for Pockels cells.^[1]

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 (high-order harmonics). 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%.

See also

• Beta barium borate (BBO) - another popular non-linear crystal
• Lithium triborate (LBO) - another popular non-linear crystal
• Monopotassium phosphate (KDP) - another popular non-linear crystal
• Non-linear optics
• Potassium titanyl phosphate (KTP) - another popular non-linear crystal
• Second harmonic generation (SHG)
• Third harmonic generation (THG)
• Two-photon absorption (TPA)
• Organic nonlinear optical materials

References