Stable broadband fiber-coupled near infrared light sources based on a bismuth heavily doped aluminosilicate optical fiber

Abstract

Bismuth centers doped in glasses and crystals exhibit broadband near-infrared luminescence covering a spectral range from ∼1100 nm to ∼1800 nm, which could not be easily achieved with rare-earth ions. The luminescence between ∼1100 nm and 1250 nm of bismuth-doped aluminosilicate optical fibers depends on the concentration of Al3+ dopants and the bismuth active center. Nevertheless, conventional bismuth-doped aluminosilicate optical fiber fabricated by modified chemical vapour deposition exhibits strong quenching effect for near-infrared luminescence, which limits the optical gain per unit length for the optical fiber. As an alternative, using Bi-doped fiber preforms obtained from a nano-porous glass route, we have demonstrated the fabrication of bismuth-doped aluminosilicate optical fibers with Bi concentration of ∼5000 ppm without quenching. Here, we report a stable and reliable spontaneous emission spanning across 1070 nm–1250 nm with center wavelength of ∼1160 nm and 3-dB spectral bandwidth of ∼81 nm in this aluminosilicate bismuth-doped optical fiber. The spectral result could be promising for application in tunable and ultrafast fiber lasers.