Mechanism of the blue up-conversion in Tm3+/Nd3+-doped calcium aluminate glasses

Abstract

Blue up-conversion fluorescence from the Tm3+:(1)G(4)-->H-3(6) (480 nm) transition has been observed from calcium aluminate glass codoped with Tm3+/Nd3+. The mechanism for the up-conversion process consists of a two-photon process. An excitation beam with a wavelength of 791 nm first excites Tm3+ to the H-3(4) level, where Tm3+ again absorbs the 1060 nm emission from Nd3+:F-4(3/2)-->I-4(11/2) to attain the Tm3+:(1)G(4) level, Lifetime and intensity variations with compositions suggest the presence of an efficient energy transfer from Nd3+ to Tm3+, The highest 480 nm emission intensity has been obtained from the glass with 0.1 mol% of Nd2O3 and 0.2 mol% of Tm2O3.