Broadband 2 μm fluorescence and energy transfer evaluation in Ho3+/Er3+ codoped germanosilicate glass

This work reports the broadband 2 mu m emission from Ho3+/Er3+ codoped germanosilicate glasses. Spectral components of the 2 mu m emission band were analyzed and an equivalent model of four-level system was proposed to describe the 2 mu m emission band. The results suggested that Ho3+/Er3+ codoped germanosilicate glass has high effective emission bandwidth (172 nm), large emission cross section (5.18 x 10(-21) cm(-2)) and gain bandwidth (891 x 10(-28) cm(3)) which is a promising candidate for 2 mu m laser and amplifier. In addition, energy transfer mechanism between Ho3+ and Er3+ ions was investigated based on the measured fluorescence spectra and decay curves of Er3+:I-4(11/2) and I-4(13/2) levels. Energy transfer efficiency and microscopic parameters were calculated to evaluate the 2 mu m fluorescence. Moreover, a rate equation model between Ho3+ and Er3+ ions was developed to elucidate 2 mu m fluorescence behaviors. This work might provide useful guide to investigate fluorescence behavior and energy transfer mechanism of rare earth ions. (C) 2015 Elsevier Ltd. All rights reserved.