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Nonlinear

Introduction

Potassium Dihydrogen Phosphate (KDP) and Potassium Dideuterium Phosphate (DKDP) 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.

 

CASTECH's KDP & KD*P products

CASTECH supplies high quality KDP and DKDP crystals in large quantities for these 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, CASTECH also provides polishing, coating and sealed housing services for the KDP family crystals. Our engineers will serve you to select and design the best crystal, according to the laser parameters you provide.

 

Table 1. Basic Properties

 

DKDP

KDP

Chemical Formula

KD2PO4

KH2PO4

Transparency Range

200-2100 nm

(98% deuterium content)

200-1650 nm

Nonlinear Coefficients

d36 = 0.40 pm/V

d36 = 0.44 pm/V

Refractive Index (at 1064 nm)

no = 1.4948, ne = 1.4554

no = 1.4938, ne = 1.4599

Electro-optic Coefficients

r41 = 8.8 pm/V

r63 = 25 pm/V

r41 = 8.8 pm/V

r63 = 10.3 pm/V

Longitudinal Half-wave Voltage

Vπ = 2.98 KV (λ = 546 nm)

Vπ = 7.65 KV (λ = 546 nm)

Absorption Coefficients

0.006 /cm

0.07 /cm

Damage Threshold

>3 GW/cm2

>5 GW/cm2

Extinction Ratio

30 dB

 

Sellmeier Equations of DKDP: (λ in µm)

no2 = 1.9575544 + 0.2901391 λ2 / (λ2 - 0.0281399) - 0.02824391 λ2 + 0.004977826 λ4

ne= 1.5057799 + 0.6276034 λ2 / (λ2 - 0.0131558) - 0.01054063 λ2 + 0.002243821 λ4

Sellmeier Equations of KDP: (λ in µm)

no2 = 2.259276 + 0.01008956 / (λ2 - 0.012942625) + 13.00522 λ2 / (λ2 - 400)

ne= 2.132668 + 0.008637494 / (λ2 - 0.012281043) + 3.2279924 λ2 / (λ2 - 400)

 

Coatings

AR-Coatings are available with high quality upon request.