Abstract
Summary form only given. Interesting classes of solid state hosts for diode pumped lasers or for short pulse emission could be those with broad spectral bands. Although rare earth ions in glasses satisfy this condition, their use in diode pumped lasers is limited by the small stimulated emission cross section and thermal conductivity. Therefore, a crystal that fulfils all these three requirements is expected to give better performances. These characteristics could be satisfied by crystals with disordered structure such as calcium niobium gallium garnet Ca/sub 3/Nb/sub 1.6875/Ga/sub 3.187/O/sub 12/ (CNGG) and calcium lithium niobium gallium garnet Ca/sub 3/Nb/sub 1.775/Ga/sub 2.95/Li/sub 0.275/O/sub 12/ (CLNGG). These crystals have several advantages compared with ordered garnet crystals, such as YAG: low melting point (smaller than 1500/spl deg/C), broad absorption and emission bands, larger doping level with ions such as Nd/sup 3+/, better thermal properties than glasses. Though laser emission was reported for Nd/sup 3+/ in CNGG and CLNGG, the growth conditions for homogeneous crystals or fibres, the spectroscopic characteristics, the nature of nonequivalent centers, and the energy transfer peculiarities are still problems to investigate. The paper attempts to elucidate the nature of non-equivalent Nd/sup 3+/ centers leading to Nd/sup 3+/ multisites in both crystals, CNGG and CLNGG, and to discuss the energy transfer processes.
Published Version
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