Study of the Influence of Ion-Beam Etching on the Surface Roughness of Single-Crystal Sapphire

To increase the average and peak power of modern laser systems, there is a need for new materials or the possibility of modifying existing ones to create composites based on them. Such composite materials using optical materials with high thermal conductivity can serve to remove heat from the active medium. Most often, this is achieved by planting materials on an optical contact. One of the promising materials for these purposes is single-crystal sapphire, since it has a sufficiently high thermal conductivity (~23–25 W/(m · K) at 323 K) and a low temperature coefficient of linear expansion (~10^–6 K^–1 at T = 323 K). The effect of the energy and angles of incidence of argon ions on the surface roughness of A-cut single-crystal sapphire was studied in this work. In the course of the work, the effect of smoothing the surface roughness by 30% relative to the initial value of roughness in the spatial frequency range 0.049–63 μm^–1 was demonstrated. The possibility of ion treatment of such surfaces is also shown, in particular, at angles of incidence of ions ± 40° on the sample surface, the value of effective roughness does not change much, which allows local correction of shape errors without leading to significant changes.