Near ultraviolet to near infrared luminescence spectroscopy of Er3+ doped K2GdF5 crystal

The detailed luminescent properties of K2GdF5 crystal doped with Er3+ was investigated using excitation spectra, emission spectra and emission decay curve measurements. The excitation bands corresponding to the characteristic Gd3+ 4f-4f transitions in the excitation spectra of Er3+ emission indicate an efficient energy transfer from host Gd3+ to doping Er3+ ions. Meanwhile, the distinct features observed only in the emission spectra excited with shorter wavelengths (≤312 nm) are assigned to the transitions from 2P3/2 levels of Er3+. This assignment is further supported by the decay curves measurements and the obtained lifetime of 2P3/2 emission (460 μs) is longer than that of 4S3/2 emission (248 μs). The luminescence in near infrared (NIR) range from 750 to 1650 nm consists of several well-distinguished bands dominated by the emission around 1540 nm corresponding to the transition of 4I13/2→4I15/2. NIR quantum cutting processes are observed and discussed with reference to the NIR emission spectra.