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KDP Crystal

POC-OC-122412-KDP Crystal

  • Broad transparency range (200–1500 nm) with excellent UV radiation transmission.
  • High laser-induced damage threshold, exceeding 5 GW/cm² at 1064 nm.
  • Stable electro-optic coefficients suitable for Pockels cells and Q-switches.
  • Custom crystal dimensions and coatings available upon request.
  • High optical homogeneity and low birefringence for precise optical performance.

Customizable Components Available for This Material to Meet Your Specific Needs!

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Material General Description of  KDP Crystal 

Potassium Dihydrogen Phosphate (KDP) is a widely used nonlinear optical (NLO) material, known for its exceptional UV transmission, high damage threshold, and reliable electro-optic performance. Its applications span frequency doubling, tripling, and quadrupling of Nd:YAG lasers at room temperature. Additionally, KDP serves as an excellent electro-optic material in Pockels cells, Q-switches, and modulators due to its high electro-optic coefficients and low refractive indices. These properties make KDP crystals indispensable in applications requiring high optical clarity, minimal birefringence, and high-power laser compatibility. CASTECH offers high-quality, customizable KDP crystals optimized for specific laser parameters and environmental conditions

 

General Applications

  1. Nonlinear Optical Applications
    • Frequency doubling (SHG) of Nd:YAG lasers to generate green light at 532 nm.
    • Frequency tripling (THG) and quadrupling for UV laser generation in high-power laser systems.
    • Second and third harmonic generation in Ti:Sapphire and Alexandrite lasers.
  2. Electro-Optic Applications
    • Widely used in Pockels cells for Q-switching, enabling precise modulation of laser outputs.
    • Essential in optical modulators for laser intensity and polarization control.
  3. Scientific and Industrial Uses
    • UV spectroscopy systems due to excellent UV transmission and high laser-induced damage threshold.
    • Laser-based lithography and precision micromachining.

Examples: KDP crystals are integral in laser frequency doubling, achieving efficient green laser generation (532 nm) and high-energy UV light generation through tripling or quadrupling. They also form the core of Pockels cells in advanced laser systems used in scientific research and industry.

Chemical and Structural Properties

Property

KDP (KH₂PO₄)

DKDP (KD₂PO₄)

Chemical Formula

KH₂PO₄

KD₂PO₄

Transparency Range (nm)

200–1500

200–1600

Lattice Parameters (Å)

a = 7.448, c = 6.977

a = 7.497, c = 6.854

Density (g/cm³)

2.332

2.355

Nonlinear Coefficient (d₃₆) (pm/V)

0.44

0.40

Refractive Indices (1064 nm)

nₒ = 1.4938, nₑ = 1.4599

nₒ = 1.4948, nₑ = 1.4554

Electro-optic Coefficients (pm/V)

λ₄₁ = 8.8, λ₆₃ = 10.3

λ₄₁ = 8.8, λ₆₃ = 25.0

Longitudinal Half-wave Voltage (kV)

Vπ = 7.65 (λ = 546 nm)

Vπ = 2.98 (λ = 546 nm)

Damage Threshold (GW/cm²)

>5

>3

Optical and Nonlinear Optical Properties

Property

Value for KDP

Value for DKDP

Transparency Range (nm)

200–1500

200–1600

Refractive Indices (1064 nm)

nₒ = 1.4938, nₑ = 1.4599

nₒ = 1.4948, nₑ = 1.4554

Nonlinear Coefficients (pm/V)

d₃₆ = 0.44

d₃₆ = 0.40

Sellmeier Equation (λ in µm):

  

– KDP

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

 

– DKDP

nₒ² = 1.957554 + 0.2091391λ² / (λ² – 0.0281399) – 0.02824391λ² + 0.004977826λ²

 

Damage Threshold (1064 nm) (GW/cm²)

>5

>3

Standard Fabrication Specifications

Specification

Value

Dimension Tolerance (mm)

W x H ± 0.1 x L ± 0.2

Angle Tolerance (°)

Δθ ≤ 0.25°, Δφ ≤ 0.25°

Parallelism (arc seconds)

<20

Perpendicularity (arc minutes)

<5

Surface Flatness

λ/8 @ 633 nm

Scratch and Dig

20/10

Damage Threshold (AR Coated)

>5 GW/cm² @ 1064 nm (10 ns, 10 Hz)

Coating

AR coatings on both surfaces

Spectrum Transmission Curve:

(Spectrum transmission curves for KDP crystals can be provided upon request, showcasing excellent UV and visible light transmission characteristics.)

Coating Specification:

  • AR Coatings: Anti-reflective coatings for 532 nm and 1064 nm wavelengths with high durability.
  • Dual-band Coating: Optimized for SHG and THG applications with low reflectance (<0.2% at 1064 nm and <0.5% at 532 nm).
  • Customization: Other coatings (e.g., BBAR, HR) are available upon request based on application requirements.
  • Adhesion Test Compliant with MIL-C-675C military standards, an adhesion test involved applying a tape that meets LT-90 specifications onto the lens film layer. The tape was affixed fully and then removed vertically. This procedure was performed three times, resulting in no blistering or peeling.
  • Temperature Test In line with MIL-C-675C specifications, test pieces were subjected to temperatures of -62±1℃ and 71±1℃. After maintaining them at room temperature (16℃~32℃) for two hours, the adhesion test was repeated, confirming no film detachment.
  • Abrasion Resistance Test Conforming to MIL-C-675C and CCC-C-440 standards, the abrasion resistance test involved a gauze tester applying a minimum force of 1.0 lbs (0.45 kg) to the film. This was repeated 25 times with gauze widths of 1/4 inch (6.4mm) and 3/8 inch (9.5mm), ensuring no damage occurred to the film surface.
  • Humidity Test Under MIL-C-675C criteria, the test piece was placed in a controlled temperature and humidity chamber set to 49 ±2℃ and 95%~100% humidity for 24 hours. The film remained intact, with no peeling, scratches, or other defects.
  • Solvent and Cleaning Testing Following MIL-C-675C specifications, test pieces were exposed to room temperature conditions (16℃~32℃) and tested with acetone and alcohol for at least 10 minutes each. After air drying and subsequent cleaning with a cotton cloth soaked in alcohol, the film surface showed no signs of peeling or scratches.
  • Salt Spray Test After 100 hours in a 35°C environment with a 5% saltwater concentration, the film showed no signs of damage.

 

POC Strength and Capabilities

POC provides superior quality KDP crystals with extensive customization options to suit specific industrial and scientific applications. High optical homogeneity, precision polishing, and robust coatings ensure compatibility with high-power laser systems. Our engineering team assists in designing and producing crystals tailored to your laser parameters, ensuring optimal performance.

Standard Products

Material

Dimensions (mm)

Coatings

Application

Price (USD)

KDP

12 x 12 x 12

AR 532/1064 nm

SHG @ 532 nm

470

DKDP

15 x 15 x 20

AR 1064 nm

THG @ 1064 nm

580

Custom

Upon Request

Custom Coatings

Specified Application

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POC-OC-122412-KDP Crystal

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