Zinc germanium phosphide (ZGP or ZnGeP2) single crystal has large nonlinear coefficients (d36=75pm/V), wide infrared transparency range(0.75-12μm), high thermal conductivity(0.35W/(cm·K)), high laser damage threshold (2-5J/cm2)and well machining property, ZnGeP2 (ZGP crystal) was called the king of infrared nonlinear optical crystals and is still the best frequency conversion material for high power, tunable infrared laser generation.Because of these unique properties, ZGP crystal is known as one of the most promising materials for nonlinear optical applications. ZGP can generate 3–5 μm continuous tunable laser out put through the optical parametric oscillation (OPO) technology. Lasers, operating in the atmospheric transmission window of 3–5 μm are of great importance for many applications, such as infrared counter measure, chemical monitoring, medical apparatus, and remote sensing.

We provide high optical quality ZGP crystals with extremely low absorption coefficient α < 0.05 cm-1(at pump wavelengths 2.0-2.1 µm), which can be used to generate mid-infrared tunable laser with high efficiency through OPO or OPA processes.

Basic properties:

Crystal Symmetry and Class
tetragonal, -42m
Lattice Parameters
a =  5.467 Å 

c = 12.736 Å

4.162  g/cm3
Mohs Hardness
Optical Class
Positive uniaxial
Userful Transmission Range
2.0 um - 10.0 um
Thermal Conductivity  
@ T= 293 K
35 W/m∙K (⊥c)
 36 W/m∙K ( ∥ c)
Thermal Expansion
@ T = 293 K to 573 K

17.5 x 106 K-1 (⊥c)

15.9 x 106 K-1 ( ∥ c)


  • Second, third, and fourth harmonic generation of      CO2-laser

  • Optical parametric generation with pumping at a wavelength of 2.0 µm

  • Second harmonic generation of CO-laser

  • Producing coherent radiation in submillimeterrange from 70.0 µm to 1000 µm

  • Generation of combined frequencies of CO2- and CO-lasers radiation and other lasers are working in the crystal transparency region.

Technical Parameters:

  • Diameter Tolerance: +0/-0.1 mm

  • Length Tolerance: ±0.1 mm 

  • Orientation Tolerance : <30 arcmin

  • Surface Quality: 20-10 S-D

  • Flatness: λ/4@632.8 nm

  • Parallelism: <30 arcsec

  • Perpendicularity: <5 arcmin

  • Chamfer: <0.1 mm x 45°

  • Transparency range: 0.75 - 12.0 um

  • Damage Threshold: 60 MW/cm2 ,150ns@10.6μm