Luminescence properties of deformed CaO crystals

In deformed CaO crystals, the predominant optical-absorption band at 270 nm and the corresponding luminescence band at 450 nm have been investigated. The absorption coefficient increases linearly with deformation up to {~}5% whereas the luminescence intensity saturates earlier. Thermal annealing indicates that appreciable decrease in the absorption begins at {~}600 K. In contrast, the luminescence intensity diminishes very rapidly at temperatures not much above room temperature. Time-resolved luminescence indicates that the 450-nm band is composed of two bands: a 475-nm band with lifetimes of 3 ns and {~}10 {μ}s, and a 440-nm band with a lifetime of {~}1 ms at room temperature. In a test for laser action no optical gain was observed in a deformed CaO crystal.