NLO Crystals

/KDP & DKDP Crystal Potassium Dihydrogen Phosphate and Potassium Dideuterium Phosphate

KDP & DKDP Crystal Potassium Dihydrogen Phosphate and Potassium Dideuterium Phosphate

KDP Potassium Dihydrogen Phosphate and KD*P or DKDP Potassium Dideuterium Phosphate 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.

  • Product Origin:

  • Shipping Port:

    Fuzhou, China
  • Lead Time:

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  • Product Detail


KDP Potassium Dihydrogen Phosphate and KD*P or DKDP Potassium Dideuterium Phosphate are one of the oldest used nonlinear materials. DKDP and KDP are known as analogs, though their properties differ due to DKDP deuteration. They both exhibit excellent ultraviolet transmission and high damage threshold. The nonlinearity of these crystals is relatively low, these crystals can be grown in large size. They found their application as nonlinear frequency doublers, triplers, and quandruplers of Nd-doped lasers and as Q-switch devices for Ti:Sapphire, Alexandrite, Nd-doped lasers. The main drawback is that these crystals are highly hygroscopic, therefore sealed housing and dry operating conditions have to be ensured.

Main applications:

1) Laser frequency conversion — harmonic generation for high pulse energy;

2) Electro-optical modulation;

3) Q-switching crystal for Pockels cells;


1) Good UV transmission;

2) High birefringence

3) High optical damage threshold;

4) High nonlinear coefficients;

5) Non-hygroscopic, chemically and mechanically stable

6) Wide working temperature range

7) Low capacitance

Basic properties



Chemical Formula



Transparency Range



Nonlinear Coefficients



Refractive index@1064nm



Electro-optical Coefficients





Longitudinal half-wave voltage






Optical damage threshold



Extinction ratio


Sellmeier equations of KDP (λ in μm)


Sellmeier equations of KD*P (λ in μm)


HGO offers KDP or DKDP specifications:

Tolerance of cutting angle


Tolerance of dimension

Dimension+0/-0.1 mmL±0.1mm


λ/10 @ 632.8nm

Wavefront distortion

λ/8@ 632.8nm

Surface quality

10/5 per MIL-O-13830A





Clear Aperture:

> 90%


< 0.1 mm @ 45°


Upon customer request


AR/HR coating upon customer’s request

Damage Threshold

750MW/CM2 at 1064nm, TEM00, 10ns, 10Hz

Quality Warranty Period

One year under proper use

Why Choose HGO ?

HGO supplies high quality KDP and KD*P crystals for various applications. Because their polished surfaces are easier to be moistened, the user is advised to provide the dry condition (<50%) and the sealed housing for preservation. For this purpose, HGO also provides polishing and sealed housing services for the KDP-based crystals. Our engineers will serve you to select and design the best crystal, according to the laser parameters you provide.

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