Nonlinear Optical Crystals: KDP & DKDP

Potassium Dihydrogen Phosphate (KDP) and Potassium Dideuterium Phosphate (KD*P ) 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 under 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.

Applications:

• Second, third, and fourth harmonic generation of Nd:lasers.
• Frequency doubling of dyer laser
• High power laser frequency conversion materials
• Shutter for high speed photography
• Electro-optical modulator and Q switches

KDP and KD*P(DKDP) Standard Orientation
Process (PM type)	KDP		KD*P (DKDP)
	Orientation	Deff(pm/V)	Orientation	Deff(pm/V)
SHG (II): 1064 nm -> 532 nm	58.9	0.34	53.5°	0.34
THG (II): 1064+532 -> 355 nm	58.4	0.37	59.4°	0.33
SFG (II): 1064+(421-1000 nm) -> 302-515 nm	61.0	0.36	63.7°	0.31
FHG (I): 532 nm -> 266nm	76.7	0.46	85.9°	0.43
NCPM FHG (I): 532 -> 266 nm	90°(T=250°C)	0.47	90°(T=55°C)	0.43
SHG (I): 1064 nm -> 532 nm	41.1	0.26	36.6°	0.22
THG(I): 1064+532 -> 355 nm	47.4	0.32	46.8°	0.29