Potassium Dihydrogen Phosphate / Potassium Dideuterium Phosphate (KDP, DKDP or KD*P)
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 |
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