KDP &DKDP

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 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, Pocket Cells, etc.

Application

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
 

 

 Basic Properties

  KDP  DKDP
Chemical Formula  KH2PO4  KD2PO
Transparency Range  200-1500nm  200-1600nm 
Nonlinear Coefficients  d36=0.44pm/V  d36=0.40pm/V 
Refractive Index (at 1064nm)  no=1.4938, ne=1.4599  No=1.4948, ne=1.4554 
Electro-optical Coefficients r41=8.8pm/V r41=8.8pm/V
r63=10.3pm/V  r63=25pm/V 
Longitudinal Half-wave Voltage  Vp=7.65KV(λ=546nm) Vp=2.98KV(λ=546nm)
Absorption  0.07/cm  0.006/cm 
Optical Damage Threshold  >5GW/cm2  >3GW/cm2 
Extinction Ratio    30dB 
Sellmeier Equations of KDP 
no2 = 2.259276 + 0.01008956/(λ2 - 0.012942625) + 13.005522λ2/(λ2 - 400)
ne2 = 2.132668 + 0.008637494/(λ2 - 0.012281043) + 3.2279924λ2/(λ2 - 400)
Sellmeier Equations of DKDP 
 no2 = 1.9575544 + 0.2901391/(λ2 - 0.0281399) - 0.02824391λ2 +0.004977826λ4
ne2 = 1.5005779 + 0.6276034/(λ2 - 0.0131558) - 0.01054063λ2 +0.002243821λ4

Orientation

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 0.36 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

Capability

Common Specification
Transmitted Wavefront Distortion ≤Lambda/8@633nm 
Dimension Tolerance ±0.1mm
Flatness Lambda/8@633nm
Parallelism  <20 arc seconds
Perpendicularity  <10 arc minutes
Angle Tolerance <10 arc minutes
Surface Quality (Scratch-Dig) S/D 20-10
Clear Aperture > 90% Central Area
Working Temperature 25˚C