Co-Doping Effect of Bismuth Ions on the Gain Characteristics of Er-Doped Silica Optical Fiber

By examining the spectral and amplification characteristics of Er-doped silica fiber (EDSF) and Bi/Er co-doped silica fiber (BEDSF), an active doped silica fiber with broadband- and flat-gain is investigated. Results show that the bandwidth of BEDSF with a gain greater than 20 dB is approximately 50 nm. Moreover, in the entire C-band, the gain of BEDSF exceeds 26 dB with a fluctuation range of approximately 2 dB. The excellent performance may mainly come from the role of bismuth ions. Further analysis demonstrates that the emission and gain cross-sections are enhanced, the bandwidth is broadened, and the flatness is also optimized by co-doping Bi ions. The fluorescence lifetime of Er3+ is lengthened by 1.82 ms, illustrating that there may exist energy transfer from Bi-related active centers to Er3+. The results indicate that the proposed BEDSF has significant potential application in optical fiber amplifiers, lasers, sensors, and so on.