Investigation of energy transfer and frequency upconversion in Ho 3+/Yb 3+ co-doped tellurite glasses

Abstract

A serials of Ho 3+/Yb 3+ 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 Ho 3+/Yb 3+ co-doped tellurite glasses centered at 549 and 664 nm corresponding to Ho 3+: 5S 2( 5F 4)→ 5I 8 and 5F 5→ 5I 8 transitions, respectively. The upconversion intensities of red and green emissions in Ho 3+/Yb 3+ co-doped glasses were enhanced largely when increasing Yb 2O 3 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 D 2, C D 3 and C D 4 were C D 2=5.0×10 −18 cm 3/s, C D 3=1.5×10 −17 cm 3/s, C D 4=9.0×10 −17 cm 3/s.