Laser Components now offers a range of gold diffraction gratings, manufactured by Optometrics Corporation, which it says are particularly well suited to use with IR lasers. Custom rulings are made directly into a layer of gold, which can be deposited on a substrate of copper, invar, ceramic or silicon substrate (although it is possible to work with other substrate materials).
In addition to the increase in efficiency exhibited (typically >/= 95 per cent, peak, polarised) the gratings offer a degradation resistance that allows them to be used in high power applications that might damage components with a thinner coating of gold, or those on an aluminium substrate. Gold gratings are offered in rulings from 70 to 450 grooves/mm, covering the 4-12µm wavelength range.