Bulk and plasma fluorescence of lithium niobate during nanosecond and picosecond laser irradiation

Time and wavelength resolved broad-band fluorescence centered at approximately 560 nm was observed using a streak camera during laser irradiation of single-crystal congruent lithium niobate. Fluorescence was monitored from approximately 40K to room temperature. Either two bands of differing lifetimes are present or else a different model such as a donor-acceptor model is necessary. An excimer laser was used to produce 24 ns pulses at 308 nm and an amplifier chain produced amplified ps pulses also at 308 nn. Fluorescence intensity depended on the pulse repetition rate. Fluorescence emission from the plasma plume was also observed for sufficiently intense emission along with evidence of incubation effects. We also present visible absorption data obtained following excimer laser irradiation at low temperature. No significant difference in fluorescence was observed between ns and amplified ps pulses.