Near infrared and upconversion luminescence of Tm3+-Yb3+codoped CdF2 single crystals

Abstract

Tm3+, Yb3+: CdF2 single crystals with good optical quality are grown by the standard Bridgman method. The crystal structure is checked by means of X-ray diffraction analysis. Under 800 nm excitation of Tm3+ ions, the samples show an intense infrared band around 1800 nm associated with the 3F4→3H6 transition. The sample exhibit also upconverted luminescence under 975 nm laser excitation which is a signature of an efficient energy transfer between Yb3+ and Tm3+ ions. The pump power dependence of all upconversion intensities have been analyzed in accordance with a proposed upconversion mechanism. The temporal evolution curves of the upconversion emissions obtained for the lowest Tm3+ concentration sample gives longer decays and as result the highest emission upconversion intensities.