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ZGP (ZnGeP2) Crystals

  • Wide transmission region from 0.74μm to 12μm
  • Large nonlinear coefficient
  • Broad phase-matching bandwidth
  • AR/BBAR coatings 
  • Applications: SHG, SFG, OPO and OPG/OPA in the mid-infrared region
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Specifications:

Material ZnGeP2 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 a promising mid-IR nonlinear crystal, exhibiting outstanding NLO properties. ZnGeP2 (ZGP) crystals have large nonlinear susceptibility (d36~75 pm/V), which is approximately 160 times that of KDP. ZGP crystals are also optically transparent over the 0.74–12μm wavelength region, with a relatively high laser damage threshold, and are therefore recommendable for producing tunable laser output in the near-infrared spectrum. ZGP Crystals could accommodate various applications including SHG, SFG, OPO, and OPG/OPA.


Applications of ZGP Crystals:

1. Second, third, and fourth harmonic generation of CO2 laser

2. Optical parametric generation (OPO) with pumping at wavelengths of 2.05-2.94μm and the possibility to generate effectively 3-10μm light

3. Producing coherent radiation in sub-millimeter-range from 70.0μm to 1000μm - terahertz range

4. Generation of combined frequencies of CO2 and CO lasers radiation and other lasers working in the crystal transmission range

Curves: