Investigation of energy transfer and frequency upconversion in Ho3+/Yb3+ co-doped tellurite glasses

摘要

A serials of Ho3+/Yb3+ co-doped tellurite glasses by pumping 970 nm laser diode (LD) were demonstrated to obtain a high efficiency of infrared-to-visible upconversion. Two intense emission bands were observed in Ho3+/Yb3+ co-doped tellurite glasses centered at 549 and 664 nm corresponding to Ho3+: S-5(2)(F-5(4)) -> I-5(8) and F-5(5) -> I-5(8) transitions, respectively. The upconversion intensities of red and green emissions in Ho3+/Yb3+ co-doped glasses were enhanced largely when increasing Yb2O3 content. The dependence of upconversion intensities on excitation power and the possible upconversion mechanisms had been evaluated by a proper rate equation model. The energy transfer coefficients were estimated by fitting the simulated curves to the measured ones. The obtained three energy transfer coefficients C-D2, C-D3 and C-D4 were C-D2 = 5.0 x 10(-18) cm(3)/s, C-D3 = 1.5 x 10(-17) cm(3)/s, C-D4 = 9.0 x 10(-17) cm(3)/s. (C) 2007 Elsevier Ltd. All rights reserved.