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.

DKDP device with diameter 75mm

Standard Specifications of KDP & DKDP
Dimension tolerance: (W ± 0.1mm) x (H ± 0.1mm) x (L + 0.2mm / -0.1mm)
Transmitting wavefront distortion: less than l/4 @633nm
Clear aperture: > 90% central area
Flatness: l/8 @633nm
Surface Quality : 20/10 Scratch and Dig to MIL-O-13830A
Parallelism: better than 10 arc seconds
Perpendicularity: 5 arc minutes
Angle tolerance (degree): D(q) < ± 0.5, D(f) < ± 0.5
Size: KDP: 20x20x20mm ~ 200x200x200mm; DKDP: 15x15x15mm ~ 60x60x60mm


1. The surfaces of KDP and its isomorphic crystals are easy to be moistened. Customers should be very careful in the maintenance of crystal surfaces. The sealed housing is recommended for these crystals.

2. KDP isomorphic crystals are widely used as electro-optic modulators.