“…For example, materials, such as KBr and NaCl, are transparent in the wavelength range up to ∼20 m, but have very low strength; ZnSe and ZnS are transparent up to ∼15 microns, but their strength is still low; more traditional materials for photonics, such as Si and Ge, are quite strong, but they are transparent only up to ∼9 m and ∼13 m, respectively. Due to the transparency of diamond at wavelengths >6 m [ 17 ] and record values of hardness, it is a promising material for IR photonics [ 18 , 19 ]. For IR applications mentioned above, we need to use the diamond membranes with an aperture of about 1 mm and with thickness providing the propagation of quasi-waveguide modes, which corresponds to the range of 5–9 m. Specifically, nanocrystalline diamond (NCD) film is perfect for this goal.…”