Novel luminescence of bismuth in silica glass and fiber based on nanoporous glass

Abstract

The ultra-broadband emission spectrum of Bi-doped fiber brings new hope for improving communication rate, while there are still many obstacles on the road to its full commercialization. The method of preparing Bi-doped fiber based on nanoporous silica glass (NPSG) is expected to be the key to breaking through the bottleneck of Bi-doped fiber. In this article, we conduct an in-depth study on the luminescence behavior and up-conversion of Bi in NPSG and its fabricated fibers. It was found that aluminum and germanium ions compete for Bi active centers (BACs) in glass, and more BAC-Al is formed when the aluminum-germanium ratio is increased, and more BAC-Ge is formed when the aluminum-germanium ratio is decreased. It is verified that the luminescence principle of bismuth originates from the defects in the glass. Bismuth up-conversion occurs in glasses which possess both BAC-Al and BAC-Ge. Bi-doped fibers were fabricated using the sleeve method, and excited-state absorption was found in the fibers. The energy level diagrams of BAC-Al and BAC-Ge are drawn. This work brings us one step to the near-infrared (NIR) luminescence principle of Bi, and lays a solid foundation for Bi-doped fiber amplifiers.