Rare-Earth Pentaphosphates for Miniaturized Laser Applications.

Abstract : Neodymium pentaphosphate (DPPN) has recently emerged as a new laser compound offering a considerable improvement in operating efficiency over existing materials. Up to thirty times more Nd can be incorporated than in Nd:yttrium aluminum garnet, without substantial fluorescence quenching, linewidth broadening, life-time reduction and optical degradation of the crystal. The evaluation and testing of NdPP lasers in prototype components using optical pumping has been hindered due to the limited size, availability and quality of the single crystals. Unique modifications of conventional solution growth techniques have been devised which have yielded the largest crystals (greater than 1 cm) of NdPP currently available. Ambient control, growth temperature, rare-earth oxide to phosphoric acid ratio, and seeding were found to greatly influence nucleation, growth rate and crystal quality. An as-grown crystal of NdPP containing 10 percent yttrium, 2.5 x 3.5 x2.2 mm thick, produced 0.24 watts of output power for 1.0 watt of absorbed power using longitudinal pumping with a repetitively pulsed argon laser; the conversion efficiency is approximately 24 percent. (Author)