Three- and four-photon excited upconversion luminescence in terbium doped lutetium silicate powders by femtosecond laser irradiation

摘要

Frequency upconversion (UC) luminescence was investigated in terbium (Tb3+) doped lutetium silicate powders when the samples were irradiated with femtosecond lasers operating either at 800 nm or 1500 nm. The samples with three different Tb3+ concentrations were prepared by the combustion synthesis method. Rietveld analysis of the X-ray powder diffraction data showed the predominance of monoclinic Lu2SiO5 phase. UC luminescence signals induced by three- and four-photon absorption were identified. The mechanisms that originate the anti-Stokes luminescence were discussed.