Lanthanide optical pumping efficiency

Fluorescence Sensitization. The optical pumping efficiency and thereby the prospects for oscillation of several actinides may be improved by codoping with sensitizer ions using schemes similar to those employed for the lanthanides in Table IV. For example, the first excited J states of l)3+, Np3+, and Pu3+ could be sensitized by energy transfer from lanthanide codopants such as Ho3+, Er3+, Tm3+, and Yb3+ as in the "alphabet" Ho3+ scheme (31). Other schemes using actinides include Cf3+-sensitized Bk3+ ( 4- 6), l)3+-sensitized Np3+... 

Trivalent lanthanide ions are used extensively for optically-pumped solid-state lasers because they possess suitable absorption bands and numerous fluorescence lines of high quantum efficiency in the visible and near-infrared. Figure 35.11 summarizes the energy levels, transitions, and approximate wavelengths of trivalent lanthanide ion lasers. In cases where the transitions are to Stark levels of the ground /-state manifold, operation at low temperatures is usually required. The number of different crystalline hosts in which each ion has lased is indicated in fig. 35.1. For several ions, stimulated emission has been observed between more than one pair of / states. A frequency-selective element (e.g., prism, grating, filter) is usually added to the resonator cavity to accomplish this. 

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