1540 nm fiber laser excited upconversion luminescence in erbium-doped lead–fluoride nanocrystals

Upconversion luminescence in erbium-doped PbGeO3–PbF2–CdF2-based vitroceramic under 1540 nm infrared excitation is investigated. Luminescence signals around 410, 525, 550, 660 and 850 nm were generated and attributed to the 2H9/2, 2H11/2, 4S3/2 and 4F9/2 transitions to the 4I15/2 ground-state, and 4S3/2–4I13/2, respectively. The erbium ions excited-state emitting levels were populated through a combination of stepwise ground-state absorption, phonon-assisted excited-state absorption and cross-relaxation processes. The results also disclosed that all emission signals obtained with vitroceramic samples presented intensities three times higher when compared to the precursor glass samples. In addition, the red emission signal at 660 nm for 1540 nm pumping exhibited an expressively high intensity when compared to the green signal.