Optical Absorption, Depolarization, and Scatter of Epitaxial Single-Crystal Chemical-Vapor-Deposited Diamond at 1.064 μm

Epitaxial single-crystal chemical-vapor-deposited diamond with (100) crystal orientation is obtained from Element Six (Ascot, United Kingdom) and Apollo Diamond (Boston, Massachusetts). Both companies supply 5×5-mm squares with thicknesses of 0.35 to 1.74 mm. Element Six also provides disks with a state of the art diameter of 10 to 11 mm and a thickness of 1.0 mm. The absorption coefficient measured by laser calorimetry at 1.064 μm is 0.003 cm -1 for squares from Element Six and 0.07 cm -1 for squares from Apollo. One Apollo specimen has an absorption coefficient near those of the Element Six material. Absorption coefficients of Element Six disks are 0.008 to 0.03 cm -1 . Each square specimen can be rotated between orientations that produce minimum or maximum loss of polarization of a 1.064-μm laser beam transmitted through the diamond. Minimum loss is in the range 0 to 11% (mean=5%) and maximum loss is 8 to 27% (mean=17%). Element Six disks produce a loss of polarization in the range 0 to 4%, depending on the angle of rotation of the disk. Part of the 0.04 to 0.6% total integrated optical scatter in the forward hemisphere at 1.064 μm can be attributed to surface roughness.