Excited state absorption at 1.06 mu m as the origin of non-unity quantum yield in neodymium doped glasses

The presence of excited state absorption at the 1.06 mu m lasing wavelength of Nd doped glasses is demonstrated. The excited state absorption cross-se ction for silicate (LG680) and phosphate (LG760) glasses was extracted from gains measurements associated to a theoretical model which is described in this paper. From both measurements and the Judd-Ofelt formalism calculatio n, we show that excited state absorption effect in Nd-doped glasses is at t he origin of non-unity quantum yield. The values obtained imply that excite d state absorption in Nd doped glasses may constitute a significant optical loss, especially for silicate glass. (C) 1999 Published by Elsevier Scienc e B.V. All rights reserved.