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A broadband light source in near infrared region generated by a bismuth-doped silica fiber

Broadband fluorescent materials are widely applied to practical uses, for example, generating ultra-short pulse laser, special light sources. Fujimoto et al. discovered a new broadband infrared fluorescence from a bismuth-doped silica glass (BiSG) [1]. This broad fluorescence exists between 1000 nm and 1600 nm, and the absorption is in the visible light region. Its lifetime is 630 µs at room temperature. The optical amplification and the laser oscillation of Bi fluorescent materials are already reported by several researchers [2–4]. This broadband optical light source can also be applied to optical coherence tomography technology (OCT), because higher depth resolution is achieved by wider light source according to Δz∼1/Δv (Δz is the depth resolution, Δv is spectral width in frequency region)[5].