Enhancement of the reflectivity of beryllium oxide in the middle infrared

An analysis is made of the feasibility of enhancing the reflectivity of BeO-based materials in the middle infrared. It is shown that the deposition of a Ge film 0.8 μm thick on a BeO single crystal makes it possible to achieve a reflection coefficient of 0.992 at λ = 10.6 μm. When Ge films of thickness d≥0.3 μm are deposited on a BeO ceramic, the upper limit of the existence of surface polaritons is shifted to the low-frequency part of the spectrum, thereby eliminating their excitation by CO₂ laser radiation and making the reflection coefficient of the ceramic similar to that of single-crystal BeO.