Residual infrared absorption in as-grown and annealed crystals of Ti:Al/sub 2/O/sub 3/

Data for as-grown and partially oxidized samples of Ti:Al/sub 2/O/sub 3/ grown by the vertical-gradient-freeze technique show that the residual infrared absorption in these samples is largely due to Ti/sup 3+/-Ti/sup 4+/ pairs. In agreement with this pair model, the residual absorption in as-grown samples has been substantially decreased by annealing in a reducing atmosphere. Data for an as-grown crystal grown by the heat exchanger method indicate the presence of a second mechanism for residual absorption that may set a lower limit on the ratio of this absorption to the Ti/sup +3/ absorption used to pump laser emission.<
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