Near-infrared down-conversion in Mn~(2+)-Yb~(3+) co-doped Zn2GeO4

摘要

We report on near-infrared (NIR) down-conversion by energy transfer between Mn~(2+) and Yb~(3+) in crystalline Zn_(1.96-x)GeO_(4+1/2x):Mn_(0.04)Yb_x. In the Zn2GeO4 lattice, intrinsic defect transitions and Mn~(2+) ions act as broadband spectral sensitizers by absorbing UV-Vis (280-500 nm) photons and transferring the absorbed energy to Yb~(3+) centers in a cooperative down-conversion process. The Yb~(3+) acceptor is then the source of NIR emission at a wavelength of ~1000 nm. Efficient energy transfer is reflected by a sharp decrease in the excited state lifetime and green photoluminescence (PL) from tetrahedrally coordinated Mn~(2+) with increasing Yb~(3+) concentration, PL-excitation spectra of NIR luminescence from Yb~(3+) are identical to those of from ~(IV)Mn~(2+). A maximal energy transfer efficiency (ETE) from Mn~(2+) to Yb~(3+) and a total theoretical quantum efficiency of 63.8% and 163.8%, respectively, are estimated.