Ultra-broad near-infrared emission of Bi-doped SiO2-Al2O3-GeO2 optical fibers

Bi-doped SiO2-Al2O3-GeO2 fiber preforms are prepared by modified chemical vapor deposition (MCVD) and solution doping process. The characteristic spectra of the preforms and fibers are experimentally investigated, and a distinct difference in emission between the two is observed. Under 808-nm excitation, an ultra-broad near-infrared (NIR) emission with full-width at half-maximum (FWHM) of 495 nm is observed in the Bi-doped fiber. This observation, to our knowledge, is the first in this field. The NIR emission consists of two bands, which may be ascribed to the Bi0 and Bi+ species, respectively. This Bi-doped fiber is promising for broadband optical amplification and widely tunable laser.