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ZGP (ZnGeP2) Crystals

  • Wide transmission region from 0.74μm to 12μm
  • Large nonlinear coefficient
  • Phase matchable over a broad spectral region
  • Applications: SHG, SFG, OPO and OPG/OPA in the mid-infrared region
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Specifications:

Materials ZnGeP2 crystals Thickness Tolerance +/-0.05mm
Orientation Tolerance <0.5° Flatness less than λ/8 @ 633nm
Transmitting Wavefront Distortion less than λ/4 @ 633nm Chamfer ≤0.2mmx45°
Chip ≤0.1mm Surface Quality better than 10/5 S/D (MIL-PRF-13830B)
Parallelism ≤30 arc seconds Perpendicularity ≤15 arc minutes
Aperture >90%

 

Chemical and Physical Properties:

Chemical Formula ZnGeP2 Crystal Structure Tetragonal, 42m
Lattice Parameter a=b=5.467Å, c=12.736Å Mass Density 4.16 g/cm3
Moh Hardness 5.5 Melting Point About 1040°C
Thermal Conductivity 180 W/m/K Thermal Expansion Coefficient β,5x10-6 /K; β⊥,7.8x10-6 /K
Birefringence Positive uniaxial

 

Linear Optical Properties

Transparency range 0.74 - 12μm
Absorption coefficient α<0.05cm-1 @2050-2100nm
Refractive Indices
@ 2.05 μm
@ 2.79 μm
@ 5.30 μm
@ 10.6 μm
no = 3.1478, ne = 3.1891
no = 3.1333, ne = 3.1744
no = 3.1136, ne = 3.1547
no = 3.0729, ne = 3.1143
Sellmeier Equations(λ in μm) no2(λ) = 4.64467+5.10087/(λ2-0.13656)+4.27777λ2/(λ2-1653.89)
ne2(λ) = 4.71539+5.26358/(λ2-0.14386)+2.37310λ2/(λ2-1000.82)

 

Nonlinear Optical Properties

SHG Phase Matchable 3177 ∼ 10357nm (Type I)
NLO coefficients d36=75 ± 8 pm/V
Type Ⅰ deeo=d36 sin2ϴcos2φ
Type Ⅱ doeo=deoo=d36 sinϴsin2φ
Damage Threshold
at 2.79 μm 30 GW/cm2 (150 ps)
at 10.6 μm 1 GW/cm2 (2 ns)

Modules or Types:

Modules Crystal Dimension Application Orientation Theta/Phi deg Coatings
SHZGP-7515-54 7x5x15mm OPO @ 2.1-> 3.5-5 µm 54/0 AR@2.1µm+BBAR@3.5-5µm
SHZGP-7520-54 7x5x20mm OPO @ 2.1-> 3.5-5 µm 54/0 AR@2.1µm+BBAR@3.5-5µm
SHZGP-7525-54 7x5x25mm OPO @ 2.1-> 3.5-5 µm 54/0 AR@2.1µm+BBAR@3.5-5µm

Zinc germanium phosphide (ZnGeP2) is an excellent mid-IR nonlinear crystal with many outstanding fundamental properties. ZnGeP2 (ZGP) crystal has large nonlinear susceptibility (d36~75 pm/V), which is approximately 160 times that of KDP. ZGP exhibits good optical transparency over the 0.74–12μm wavelength region and relatively high laser damage threshold, and is therefore well suited for producing tunable laser output in the near infrared. ZGP is a very promising material for applications such as SHG, SFG, OPO, and OPG/OPA in the mid-infrared region.

 


Curves:


Applications:

  • Second, third, and fourth harmonic generation of CO2 laser
  • Optical parametric generation (OPO) with pumping at a wavelengths of 2.05-2.94μm and possibility to generate effectively 3-10μm ranges
  • Second harmonic generation of CO-laser
  • Producing coherent radiation in sub-millimeter-range from 70.0μm to 1000μm - terahertz range
  • Generation of combined frequencies of CO2- and CO-lasers radiation and other lasers are working in the crystal transparency region