I. Introduction

Though their NLO coefficients are relatively low, Potassium Dihydrogen Phosphate (KDP) and Potassium Dideuterium Phosphate (DKDP or KD*P) are among the most widely-used commercial NLO materials, characterized by good UV transmission (up to 180nm and 200nm, respectively), high damage threshold (>5 and 3 GW/cm2, respectively) and high birefringence. They are commonly used for SHG, THG and 4HG of Nd:YAG laser at room temperature. In addition, they are also excellent electro-optic crystals with high electro-optic coefficients, widely used as electro-optical modulators, Q-switches, and Pockels Cells, etc. Both KDP and DKDP crystals are grown by water solution method, and as-grown crystals of very large size can be achieved. So finished KDP and DKDP NLO devices with high quality, large sizes as well as low costs are available in Fuzhou caston optronics co., Ltd. CASTON manufactures and supplies not only as-cut KDP and DKDP blocks, but polished components with large quantities for their main applications. We also provides sealed housing services for polished KDP and DKDP crystals, because their polished surface are easy subject to moisten.

So please contact us for the further information in details of as-cut or polished KDP and DKDP crystals and services. 

KDP

DKDP

Chemical Formula

KH2PO4

KD2PO4

Crystal Structure

Tetragonal

Tetragonal

Symmetry

42m

42m

Density (g/cm3)

2.332

2.355

Mohs Hardness

2.5

2.5

Absorption Coefficient

0.07/cm

0.006/cm

Thermal Expansion Coefficient

-

a11=1.9x10-5/K a33=4.4x10-5/K

Thermal Conductivity Coefficient

-

K11 = 1.9x10-2 W/mK
K33 = 2.1x10-2 W/mK

Electro-Optical Coefficients

r41= 8.8pm/V r63=10.3pm/V

r41=8.8pm/V
r63=25pm/V

Longitudinal Half-Wave Voltage

Vp=7.65KV (l=546nm)

Vp=2.98KV (l=546nm)

Transmission Range

180-1550nm

200-2150nm

Nonlinear Coefficients

d36=0.44 pm/V

d36=0.40 pm/V

Refractive Indexes

Temp. Synchronism Width

11.5oC-cm

7.4oC-cm

Spectral Synchronism Width

106 Å-cm

32 Å-cm

Angle Synchronism Width

0.84 mrad-cm

0.94 mrad-cm

Walk-Off Angle

1.4o

1.4o

Optical Damage Threshold

>5 GW/cm2

>3 GW/cm2

Group Velocity Mismatch

1.3 ps/cm

0.95 ps/cm

Extinction Ratio

30dB

Sellmeier Equations

KDP

no2=2.259276 + 0.01008956/(l2 - 0.012942625) + 13.005522l2/(l2 - 400)
ne2=2.132668 + 0.008637494/(l2 -0.012281043) + 3.2279924l2/(l2 - 400)

DKDP

no2=1.9575544+0.2901391/(l2-0.0281399)-0.02824391l2+0.004977826l4
ne2=1.5005779+0.6276034/(l2-0.0131558)-0.01054063l2+0.002243821l4

 Main applications of KDP and DKDP crystals are listed as follows:

*SHG, THG and 4HG of Nd:lasers

*SHG of Dye laser

*Shutter for high speed photography

*Electro-optical modulators and Q-switches

*For SHG and THG of Nd:YAG laser at 1064nm, both Type I and Type II phase-matchings can be *employed for KDP and DKDP crystal. In the high power case, DKDP crystal with standard size 12x12x25, or 30 mm3 is often used. For 4HG of Nd:YAG laser, KDP crystal is normally recommended.

Typical frequency conversation of Nd:YAG laser for DKDP crystals are listed:

Dimensional Tolerance

(W±0.1mm) x (H±0.1mm) x (L+0.2/-0.0 mm)

Wavefront Distortion

< l/8 @632.8 nm

Crystal Internal Quality

No visible bubbles, inclusions and scattering sites or paths when inspected by a 30mW green laser

Cutting Angle Tolerance

Dq < ±0.3o, Df < ±0.3o

Clear Aperture

> Central 90%

Chamfer

≤ 0.2 mm x 45°

Surface Quality

10/5 Scratch/Dig per MIL-O-13830A

Flatness

< l/8 @632.8 nm

Parallelism

≤ 20 arc seconds

Perpendicularity

≤ 5 arc minutes

Quality Warranty Period

one year under proper use

Part Number

Type

Dimension

Application

Coating

CNKD-2S-1220

II

12x12x20 mm

SHG

uncoated

CNKD-2S-1225#

II

12x12x25 mm

SHG

uncoated

CNKD-2S-1230

II

12x12x30 mm

SHG

uncoated

CNKD-2T-1220#

II

12x12x20 mm

THG

uncoated

CNKD-2T-1225

II

12x12x25 mm

THG

uncoated

CNKD-2T-1230#

II

12x12x30 mm

THG

uncoated

Notes:

1) While putting orders, please indicate the application wavelength(s).

2) DKDP with P/N marked # are in stock now, we can delivery goods with
    24 hrs for polished items only, and within 48-72 hrs for AR coated.

3) DKDP of other dimensions, applications are available upon request.

LiIO3 crystals is available in CASTON .

KDP, DKDP and LiIO3 crystals are highly hygroscopic and the coating can not be available at current.

Because the polished surfaces of KDP, DKDP and LiIO3 are easy subject to moisten, Please keep them in a dry environment (<50%), and sealed housings for preservation is recommended.