Broadband near-infrared emission in Bi-Er co-doped germanosilicate glasses

Broadband gain materials have garnered considerable attention on account of their practical utilization in optical amplifiers. Among them, Bi -doped glasses depict tremendous potential due to their unique broadband emission. In this paper, we report a series of Bi -Er co-doped germanosilicate glasses exhibiting broadband and tunable near-infrared (NIR) emission. By the strategy of Bi -Er co-doping, the luminescence bandwidth is effectively expanded in two ways: co-excitation and energy transfer between two active centers. Importantly, broadband luminescence covering O -E -S -C -L bands with full width at half maximum (FWHM) more than 320 nm is realized via the way of energy transfer. In addition, ultrabroadband emission covering C -L -U bands with FWHM of -370 nm and relatively flat emission of -170 nm is achieved via the way of co-excitation. Furthermore, the mechanism of energy transfer is discussed. These results indicate that Bi -Er co-doped germanosilicate glasses are the promising candidates in the field of optical fiber amplifiers.