Upconversion luminescence in europium doped Y2O3 powder excited by absorption of three, four, and five infrared photons

Frequency upconversion (UC) luminescence was observed in yttrium oxide (Y2O3) powders doped with trivalent europium ions (Eu3+) when the samples were irradiated with a femtosecond laser system operating either at 1275 nm or 1500 nm. The samples, prepared by low temperature combustion synthesis, were characterized by X-ray diffraction, scanning electronic microscopy, spontaneous Raman scattering and photoluminescence. The UC luminescence, corresponding to the 5D0 → 7FJ (J = 1, 2, 3, 4) transitions of Eu3+, characterized by measuring the amplitude of the UC signal versus the laser intensity, is attributed to the simultaneous absorption of three, four and five infrared photons. The results indicate that Eu3+ doped Y2O3 powder is an efficient upconverter for excitation using femtosecond near-infrared lasers.