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 0.7412 um 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.
Features
Wide transmission region from 0.74 um to 12um
Large nonlinear coefficient
Good mechanical and physical properties
Relatively high damage threshold
Phase matchable over a broad spectral region
High thermal conductivity
Applications
Second, third, and fourth harmonic generation of CO2 laser
Optical parametric generation (OPO) with pumping at a wavelengths of 2.05-2.94 m and possibility to generate effectively 3-10 m ranges
Second harmonic generation of CO-laser
Producing coherent radiation in sub-millimeter-range from 70.0 m to 1000 m - terahertz range
Generation of combined frequencies of CO2 - and CO-lasers radiation and other lasers are working in the crystal transparency region
Chemical and Physical Properties
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Property
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Value
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Chemicalformula
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ZnGeP2
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Crystalstructure
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Tetragonal,`42m
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LatticeParameter
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a=b=5.467,c=12.736
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Massdensity
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4.16 g/cm3
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Mohhardness
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5.5
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Meltingpoint
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About1040°C
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Thermalconductivity
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180W/m/K
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Thermalexpansion coefficient
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‖,5x10-6/K; ⊥,7.8x10-6/K
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Birefringence
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positiveuniaxial
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Linear Optical Properties
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Property
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Value
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TransparencyRange
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0.74- 12 um
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AbsorptionCoefficient:
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<0.05cm-1@2050-2100 nm
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RefractiveIndices
@2.05 um
@2.79 um
@5.30 um
@10.6 um
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no= 3.1478, ne = 3.1891
no= 3.1333, ne = 3.1744
no= 3.1136, ne = 3.1547
no= 3.0729, ne = 3.1143
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SellmeierEquations( in m)
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no2() = 4.64467+5.10087/(2-0.13656)+4.277772/(2-1653.89)
ne2() = 4.71539+5.26358/(2-0.14386)+2.373102/(2-1000.82)
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Nonlinear Optical Properties
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Property
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Value
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SHGPhase Matchable Range
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317710357nm (Type I)
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NLOcoefficients
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d36=758 pm/V
Typedeeo=d36 sin2cos2
Typedoeo=deoo=d36 sinsin2
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DamageThreshold
at2.79 um
at10.6 um
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30GW/cm2 (150 ps)
1 GW/cm2 (2 ns)
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