Optical properties of Cr2+:ZnSe single crystal and film

To realize an electrically pumped compact mid-IR microlaser, the optical properties of a Cr(2+):ZnSe film deposited by rf magnetron cosputtering were compared with those of a single crystal. The mid-IR room temperature photoluminescence efficiency of the film appears only twice less than the one of the single crystal under direct (1850 nm) and indirect (458 nm) excitations. The smaller Cr(2+) fluorescence lifetime values of the film were attributed to the presence in the film of a large amount of chromium in a valence state different from Cr(2+) and of structural defects in the ZnSe host matrix.