Potassium Dihydrogen Phosphate / Potassium Dideuterium Phosphate ( KDP, DKDP or KD*P )
![]() |
Potassium Dihydrogen Phosphate (KDP) and Potassium Dideuterium Phosphate (DKDP) are nonlinear optical materials (NLO)know for their large NLO coefficients, wide transparency range and high optical damage threshold. These materials are widely used as frequency multipliers for generation of the second, third and fuorth harmonics for Nd:YAG, Nd:YLF lasers. Both crystals are also applied in electro-optics: as Q-switches for Nd:YAG, Nd:YLF, Ti:sapphire and Alexandrite lasers and Pockels cells. Owing to a posibility of growing large crystals, high laser frequency multipliers. Q-switches and Pockels cells, laser damage threshold of witch is over 40 J/cm2 (at lambda=1,06 µm, tau=3 ns). KDP and DKDP crystals possess elctro-optical, nonlinear and piesoelectric properties, high laser damage threshold and are used as the base for the devices and systems of laser engineering: frequency multipliers, modulators, gates, deflectors. |
Basic Properties45 | KDP | DKDP |
Chemical Fomula | KH2PO4 | KD2PO4 |
Class of symmetry | 42m | 42m |
Crystal structure | tetragonal | tretagonal |
Transparency Range, mm | 0,2 – 1,5 | 0,2 – 1,6 |
Wafelength range, nm | 200-1500 | 2 |
Electro – optical Coefficients, pm/V-1. | r41 = 8.8 r63 = 10.3 |
r41 = 8.8 3 = 25 |
Nonlinear Coefficients | d36 = 0.44 pm/V | d36 = 0.40 pm/V |
Refractive index (at 1064 nm) | n0 = 1.4938 nc = 1.4599 |
no = 1.4948 nc = 1.4554 |
Temperature Synchronism Width, oC*cm | 11,5. | 7,4. |
Spectral Synchronism Width, A | *cm | 106 |
Angle Synchronism Width, mrad*cm | 0,84 | 0,94 |
Longitudinal half-wave voltage | Vn = 7.65 KV (l = 546 nm) |
Vn = 2.98 KV (l= 546 nm) |
Absorpion Coefficient, cm-1 | 0.07 | 0.006 |
Optical Damage Threshold (l=1,064 mm, t=10ns) |
>5 GW / cm² | >3 GW / cm² |
ohs Hardness | 2,5 | 2,5 |
Extinction ratio | 30 dB | |
Sellmeier equations of DKDP | ||
n02 = 1.9575544 + 0.2901391 l2 / (l2 – 0.0281399) – 0.02824391 l2 + 0.004977826 l2 | ||
nc2 = 1.5005779 + 0.6276034 l2 / (l2 – 0.0131558) – 0.01054063 l2 + 0.002243821 l4 | ||
Sellmeier equations of KDP | ||
n02 = 2.259276 + 0.01008956 / (l2 – 0.012942625) + 13.00522 l2 / (l2 – 400) | ||
nc2 = 2.132668 + 0.008637494 / (l2 – 0.012281043) + 3.2279924 l2 / (l2 – 400) |
Refractive Index | ||||||||
Sellmeier Equation | n2 = A + B / (l2 – C) + Dl2 / (l2 – E) ( l in mm) | |||||||
Sellmeier Coeficients | KDP | KD*P | ADP | CDA | CD*A | |||
A | no | 2.2576 | 2.2409 | 2.3041 | 0.4204 | 2.4082 | ||
ne | 2.1295 | 2.1260 | 2.1643 | 2.3503 | 2.3458 | |||
B | no | 0.0101 | 0.0097 | 0.0111 | 0.0163 | 0.0156 | ||
ne | 0.0097 | 0.0086 | 0.0097 | 0.0156 | 0.0151 | |||
C | no | 0.0142 | 0.0156 | 0.0133 | 0.0180 | 0.0191 | ||
ne | 0.0014 | 0.0120 | 0.0129 | 0.0168 | 0.0168 | |||
D | no | 1.7623 | 2.2470 | 15.1086 | 1.4033 | 2.2122 | ||
ne | 0.7580 | 0.7844 | 5.8057 | 0.6853 | 0.6518 | |||
E | no | 57.8984 | 126.9205 | 400.0000 | 57 8239 | 126.8709 | ||
ne | 127.0535 | 123.4032 | 400.0000 | 127.2700 | 127.3309 | |||
l = 1064 | no | 1.4942 | 1.4931 | 1.5071 | 1.5515 | 1.5499 | ||
Typical Values |
nm | ne | 1.4603 | 1.4583 | 1.4685 | 1.5356 | 1.5341 | |
l = 532 | no | 1.5129 | 1.5074 | 1.5280 | 1.5732 | 1.5692 | ||
Typical Values |
nm | ne | 1.4709 | 1.4683 | 1.4819 | 1.5516 | 1.5496 | |
l = 355 | no | 1.5317 | 1.5257 | 1.5487 | 1.6026 | 1.5974 | ||
nm | ne | 1.4863 | 1.4833 | 1.4994 | 1.5788 | 1.5759 |