The visible emission spectra and fluorescent life-time from decayed and nondecayed regions of teeth were measured and compared. The spectrum from carious lesions is different from that of noncarious tooth regions. This may offer a non-X-ray method for diagnosing dental caries in humans.

The time dependence of both the photoluminescence due to carrier recombination and the gratings created by degenerate four-wave mixing were measured in semiconductor-doped color-filter glasses. Values ranging from 80 to less than 16 ps (laser pulse width limited) are measured in several different samples at various excitation levels. A slower mechanism, believed to be thermal in nature, is also observed with a lifetime in excess of 9 ns.