KDP(Potassium Dihydrogen Phosphate) and DKDP(Potassium Dideuterium Phosphate) are available in extremely large size with high uniformity, high damage threshold and high birefringence, though their NLO coefficients are relatively low. LNG Optics offers KDP and DKDP elements for SHG, THG and FHG of Nd lasers at room temperature, also DKDP elements for Pockels cells.
Features & Standard Specifications from LNG Optics:
Dimensions: Up to 50x50mm2 ±0.1mm
Length: Up to 60mm +0.2/-0.1mm
Orientation Accuracy: Δθ<0.2°Δφ<0.2°
Flatness: λ/8 @ 633nm
Transmitted Wavefront Distortion: λ/8 @ 633nm
Surface quality: 20/10 S/D polished, 40/20 S/D after coating
Clear Aperture: 90% central area
Parallelism: 20 arc seconds
Perpendicularity: 5 arc minutes
Chamfer: 0.2mm x 45°±5°
Laser damage threshold: KDP 5GW/cm2for 1064nm 10ns pulse
DKDP 3GW/cm2for 1064nm 10ns pulse
AR, BBAR and P-Coatings are available
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Physical and Chemical Properties: |
KDP |
DKDP |
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Chemical Formula |
KH2PO4 |
KD2PO4 |
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Crystal Structure |
Tetragonal, space group D4h |
Tetragonal, space group D4h |
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Lattice Parameters (Å) |
a=7.4529, c=6.9751 |
a=7.4697, c=6.9766 |
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Curie point (oC) |
~396 |
~495 |
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Mohs Hardness |
~2.5 |
~2.5 |
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Density (gram/cm3) |
2.332 |
2.355 |
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Hygroscopic Susceptibility |
high |
high |
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Thermal Conductivity (W/cm/K) |
k11 = 1.9 x 10-2 |
k11 = 1.9 x 10-2 k33 = 2.1 x 10-2 |
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Thermal Expansion Coefficients (K-1) |
a11= 2.5 x 10-5 a33= 4.4 x 10-5 |
a11= 1.9 x 10-5 a33= 4.4 x 10-5 |
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Resistivity (ohm•cm) |
10-20 x 106 |
10 x 106 |
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Relative Dielectric Constant @ 25oC and 1KHz |
εT11/ε0 = 43.2, εs11/ε0 = 42.5 εT33/ε0 = 20.8, εs33/ε0 = 20.0 |
εT11/ε0 = 65.0, εs11/ε0 = 62.5 εT33/ε0 = 50.0, εs33/ε0 = 48.0 |
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Optical and Nonlinear Properties: |
KDP |
DKDP |
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Transparency Range |
180-1500nm |
200-2100nm |
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Refractive index at 1064nm |
no＝1.4938, ne＝1.4599 |
no＝1.4948, ne＝1.4554 |
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NLO Coefficient @ 1064nm (pm/V) |
d36=0.44 |
d36=0.40 |
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Electro-Optics Coefficients (pm/V) |
r41=8.8, r63=10.3 |
r41=8.8, r63=25 |
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Sellmeier Equations of KDP (λ in μm) |
no2 = 2.259276 + 0.01008956/(λ2-0.012942625)+13.005522λ2/(λ2-400) |
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Sellmeier Equations of KD*P (λ in μm) |
no2 = 1.9575544 + 0.2901391λ2/(λ2-0.0281399)-0.02824391λ2+0.004977826λ4 |
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