Gallium Arsenide (GaAs)

Gallium Arsenide used for lenses and beam splitters provides an alternative to ZnSe in medium and high power CW CO2 laser systems. It is most useful in applications where toughness and durability are important. Its hardness and strength make it a good choice where dust or abrasive particles tend to build up on or bombard the optical surfaces. When frequent cleaning by wiping is required, GaAs is excellent. The material is nonhygroscopic, safe to use in laboratory and field conditions and is chemically stable except when in contact with strong acids.

Specifications of GaAs
Transmission Range 0.6 to 21.0μm
Refractive Index 2.4028 at 10μm
Reflection Loss 29.1% at 10.6μm (2 surfaces)
Absorption Coefficient 0.0005cm-1 at 10.6μm
Restrahlen Peak 45.7microns
dn/dT +61 x 10-6/°C at 10.6μm at 298K
dn/dμ = 0 5.5μm
Density 5.27g/cm3
Melting Point 1525°C (dissociates about 700°C)
Thermal Conductivity 18 W/(m K) at 298K
Thermal Expansion 7.1 x 10-6/ °C at 273K
Hardness Knoop 120 with 50g indenter
Specific Heat Capacity 339 J · kg-1 · K-1
Bulk Modulus (K) 40 GPa
Young's Modulus (E) 67.2 GPa
Apparent Elastic Limit 55.1 MPa (8,000psi)
Poisson Ratio 0.28