Development of a novel laser material for miniaturized laser systems

Our work during this quarter dealt with the growth and evaluation of NPP crystals for a 1.06 micrometer miniature laser and Er(3+) stoichiometric crystals for an eyesafe miniature laser emitting at 1.54 micrometer. Crystals of NPP up to 2x2x20 mm for fabrication of miniature laser rods were grown by a previously described high-temperature, solution-growth technique. Flash-lamp-pumped lasing experiments were conducted using various sizes of NPP crystals, in both the free-oscillation and Q-switched modes at different pulse repetition rates. Output pulse energies and properties of the laser output beam were measured. The efficiencies for the free-oscillation mode were close to the maximum published values; for the Q-switched mode, the efficiencies were low compared to published values. Crystals of ErP5O14 were grown by the same technique used for NPP; crystals of ErLiP4O12 and ErAl3(BO3)4 were grown by related fluxed-melt techniques. These crystals were several millimeters in size. Both Yb and Gd were added in various ratios as sensitizing and/or diluent ions. the absorption and emission properties of the Er3+ luminescence in some samples of ErP5O14, LiErP4O12, and ErAl3(BO3)4 have been studied both in the visible and infrared regions of the spectrum. Preliminary evaluations of these materials for laser applications have been made.