Undoped yttrium aluminum garnet (YAG) is an optical material similar to sapphire. Undoped YAG is widely used in UV and IR optics due to its mechanical and chemical characteristics.

Unlike other optical glasses with the tendency of absorption owing to strong water molecule bonds, undoped YAG carries no absorption lines in the range of 2-3 μm and can be applied in wide spectral range from 250 to 4000 μm.

High values of durability, thermal conductivity, damage threshold and the absence of birefringence allow undoped YAG to be successfully employed in applications pertaining to aggressive external impact and sensitive to optical distortion, including high temperature utilization and high-power laser usage.

Linear defects deficiency and high material homogeneity of Monocrystal undoped YAG crystals enable to produce polished windows, optical waveguides, prisms and other optical items with clear aperture up to 8".

Yttrium Aluminum Garnet (YAG): Zero-birefringence and High Thermal Conductivity

Thermal conductivity

Significantly higher than that of most glasses.


Exceptionally solid and robust material for the manufacturing of polished items.

High damage threshold

Wide spectral range

From 250 to 4000 μm.

High refraction index

Which allows to produce low aberration lenses.


Properties of yttrium aluminum garnet

Parameter Value
Orientation [100] or [111]
Formula Y3Al5O12
Melting point 1950 °C
Mohs scale hardness 8 - 8,5
Density 4,55 g/cm 3
Thermal conductivity 0,14 W/ cm°C
dn/dt 7,4 х 10 -6 ° С -1
Thermal expansion 6,9 х 10 -6 ° С -1
Index of refraction

  • at 0,8 mm
  • at 0,9 mm
  • at 1,0 mm
  • at 1,2 mm
  • at 1,4 mm

  • 1,8245
  • 1,8222
  • 1,8197
  • 1,8152
  • 1,8121
Damage threshold > 15 J/cm 2
Wavefront distortion < l / 2
Diameter tolerance +/- 0,05 mm
Flatness < l/10 at 633 nm
Scratch-dig (per MIL-O-13830A) 10-5