Evaluation of cross sections of rare-earth ions in glass

Abstract

ABSTRACT An approach based on the theory of McCumber is described to calculate the emission cross sections of a transition of therare-earth ions in glass. It overcomes the drawback of the theory that the knowledge of the electronic structures of the rare-earth ions is usually demanded to determine the emission cross section. Instead, only the measurement of the absorptionspectra of the ions is necessary. The Judd-Oflet theory is used to determine the energy parameters. The emission cross sections of Tm3, Er and Yb in fluoride glasses are calculated. The results are consistent with those reported before, which indicates the method is simple and quite effective.Key words: Emission cross section, rare-earth ions, optical property, the theory ofMcCumber, the Judd-Oflet theory 1. INTRODUCTION Absorption and emission cross sections are important parameters to analyze the performance of rare-earth ion doped lasersand amplifiers. Absorption cross sections can be easily derived from absorption spectrum if the ion concentration is known.However, the determination of emission cross sections is not so easy. Generally, the Fu chtbauer-Ladenbury (FL) equationis used, in which the emission cross section was obtained from the fluorescence spectrum, the radiative lifetime ofthe upper