Samarium doped alkaline earth halide thin films as spectrally selective materials for hole burning?

Optical hole burning, a potential technique for spectrally selective Recording, was demonstrated in Sm-doped MBE-grown thin films of CaF₂/Si(111). The inhomogeneous broadening of the corresponding Sm²⁺ 5d(T_1u) ↞ 4f(⁷F₀, A_1g) transition (690 nm) was investigated as a function of substrate temperature and film thickness. The MBE apparatus is briefly described as well as the thin film growth procedure.