On the upconversion emission of rare earth doped zirconia fiber

Optical rare earth doped zirconia fiber were produced using a CO2 laser and upconversion emission from a ZrO2:Er3+:Y3+:Pr3+ crystal fiber sample has b een observed. The experiment was done exciting the Er3+ ion through the 647 -676.4 nm multilines of a Kr+ laser, resulting in a broad and structured em ission around 550 nm. From well known Er3+ doped LiNbO3 emission it is conc luded the upconversion emission results from the (2)H(11/2)double right arr ow(4)I(15/2) (510-540 nm) and from the S-4(3/2) double right arrow I-4(15/2 ) (540-570 nm) Er3+ transitions. Regardless of the Er3+ electron shielding and the broadened emission observed in the zirconia, the shape of the emiss ion spectra is very similar to the one observed in the LiNbO3 sample. Some possibilities arise from these results. The Er3+ ion is sitting in many mul tiequivalent and different sites in the zirconia (cubic symmetry) rather th an in the LiNbO3 (hexagonal symmetry).