Upconversion Luminescence in γ‐AlON:Yb 3+ ,Tm 3+ Ceramic Phosphors

Upconversion emission properties of γ‐AlON:Yb 3+ ,Tm 3+ phosphors were investigated under single‐wavelength diode laser excitation of 980 nm. Blue (479 nm) and red (653 nm) emission bands were observed which correspond to the transitions of 1 G 4 → 3 H 6 and 1 G 4 → 3 F 4 of Tm 3+ ions, respectively. The upconversion spectra show a concentration‐dependent luminescence intensity, reaching its peak at a concentration of 1.2 mol% Yb and 0.5 mol% Tm. Pump power dependence of the upconversion emission intensity ( P – I ) revealed that a two‐photon process was involved in the blue and red emissions.