Measurements of absorption and excitation spectra for Nd<sup>3+</sup> in soda-lime silicate glass, CaWO<sub>4</sub>, and Y<sub>3</sub>Al<sub>2</sub>(AlO<sub>4</sub>)<sub>3</sub> (YAG) are presented. The relative quantum efficiency for <sup>4</sup><i>F</i><sub>3/2</sub> → <sup>4</sup><i>I</i><sub>11/2</sub> fluorescence is evaluated for principal absorptions over the wavelength range 3250–9300 Å. For the crystals, quantum efficiency is found to be independent of the level pumped, to within ±12% for CaWO<sub>4</sub> and ±13% for YAG. Except for slight quenching of levels between 4000 and 5500 Å, quantum efficiency for the glass sample is independent of pumping level to within ±5%. These results indicate that the efficiency of each step in the process which populates the <sup>4</sup><i>F</i><sub>3/2</sub> level is near unity. Also, over the range of structures investigated, relative Nd<sup>3+</sup> quantum efficiency appears to be independent of the details of crystal-field structure.
RICHARD A. BRANDEWIE and CHARLES L. TELK, "Quantum Efficiency of Nd3+ in Glass, Calcium Tungstate, and Yttrium Aluminum Garnet," J. Opt. Soc. Am. 57, 1221-1225 (1967)