Observation of Laser-Induced Fluorescence Line Narrowing in Glass: Nd

Laser-induced fluorescence line narrowing has been observed for the first time in a nonresonantly excited rare-earth system. Excitation with the 4727-Å $A^{+}$ line into the ${}_{}{}^4{}_{}{}^{}G_{\frac{11}{2}}^{}{}_{}{}^{}$ level of ${\mathrm{Nd}}^{3+}$ in glass results in narrowing of transitions from the ${}_{}{}^4{}_{}{}^{}F_{\frac{3}{2}}^{}{}_{}{}^{}$ to both the ${}_{}{}^4{}_{}{}^{}I_{\frac{9}{2}}^{}{}_{}{}^{}$ ground manifold and the ${}_{}{}^4{}_{}{}^{}I_{\frac{11}{2}}^{}{}_{}{}^{}$ excited manifold. The concentration dependence of the line narrowing provides information regarding resonant ion-ion energy transfer within the inhomogeneously broadened system.