Upconversion luminescence properties of nanocrystallite MgAl2O4 spinel doped with Ho3+ and Yb3+ ions

The upconversion luminescence spectra of nanocrystallite MgAl2O4 doped with 1% of Ho3+ and 5% of Yb3+ ions after excitation at 980 nm were measured. Influence of excitation regime either continuous or pulse on upconversion mechanisms was shown. For continuous wave (CW) laser excitation upconversion process is due to phonon assisted Excited State Absorption (ESA). For pulse laser excitation upconversion emission is due to Energy Transfer Upconversion (ETU).

► Nanocrystallite MgAl2O4 doped with 1% of Ho3+ 5% of Yb3+ were examined.
► Excitation at 980 nm produces upconversion, which depends on excitation regime.
► Continuous excitation produces mainly red emission due to Excited State Absorption.
► After pulse excitation green emission due to Energy Transfer Upconversion is seen.