CVD Diamond:
Optical Properties

The excellent optical properties of diamond have been known for a long time. However, optical applications require extended discs or thin coatings not provided by natural diamond crystals. With the development of CVD techniques the situation has changed completely.
 

Broadband transparency

Diamond is transparent from the UV (230 nm) to the far infrared. Only minor absorption bands resulting from two phonon absorption exist between 2.5 and 6 µm. Hence diamond is an ideal material for multispectral optical applications. 

Wide band gap

No thermal generation of charge carriers at elevated temperatures, hence no "thermal run away" as in the case of Germanium under laser irradiation. Furthermore, diamond does not become nonlinear at high radiation intensities. 

High thermal conductivity

Absorbed energy is quickly dissipated to the edges of a diamond window where it can be removed by appropriate heat sinks and cooling techniques. 

Mechanical and chemical stability

Diamond is extremely hard, wear resistant and chemically inert. 
It is an ideal material for hostile, highly erosive atmospheres. 

Optical transmission spectrum of CVD diamond