Sensitizing effect of Yb3+ ions on photoluminescence properties of Er3+ ions in lead phosphate glasses: Optical fiber amplifiers

The Er3+/Yb3+-codoped lead phosphate (PPbKANErYb) glasses have been prepared by using melt quenching technique and characterized through spectroscopic studies such as absorption, emission, decay and upconversion measurements. An intense near-infrared (NIR) emission at 1.53 mu m was observed which has been explained based on the effective energy transfer from Yb3+ to Er3+ ions. The absorption (I-4(15/2) -> I- 4(13/2)) and emission cross-section (I-4(13/2) -> I-4(15/2)) of 1.53 mu m emission band was calculated and found to be of the order of 6.76 x 10(-21) and 7.9 x 10(-21)cm(2), respectively, by using the McCumber theory. The PPbKANErYb glasses exhibit higher luminescence intensity (more than 3 times) and full width at half maxima (55 nm) compared to 1.0 mol% Er3+ singly doped glass (50 nm). All the decay curves of the I-4(13/2) level exhibited single exponential nature and the lifetimes increased (1760, 1776, 1942 and 2830 mu s) with the increase of Yb2O3 (0.5, 1.0, 2.0 and 3.0 mol %) concentration. Intense red band at 670 nm corresponding to F-4(9/2) -> I- 4(15/2) transition and green emission bands at around 530 and 555 nm corresponding to H-2(11/2) -> 4I(15/2) and S-4(3/2) -> I-4(15/2), transitions, respectively, have been observed under the excitation of 980 nm. The intensity of the upconversion emissions is found to be increased with the increase of Yb3+ ion concentration and its mechanism have been explained. The luminescence decay curves of the( 4)S(3/2) -> I-4(15/2) upconversion luminescence of Er3+/Yb3+ codoped PPbKAN glasses under the infrared excitation of 980 nm have been evaluated. The results reveal that the investigated glasses might be potential candidates for optical fiber amplifiers/laser sources at 1.55 mu m band.