We report a novel PbS/Er co-doped silica fiber (PEDF) with improved spectral properties in O-band (1260-1360 nm). The results show that the gain of the PEDF exceeds 15 dB in the range of 1150-1360 nm. Compared to PbS-doped silica fiber, the PEDF has a gain improvement of 6.4-10.9 dB in O-band. In addition, the concentration of Pb and S in the PEDF core is significantly higher, and the size distribution of PbS nanoparticles is more concentrated in a narrow range. These factors may account for the enhanced gain characteristics of the PEDF. This work reveals the positive effect of co-doping Er 3+ ions on the gain characteristics of the PEDF in O-band, and suggests an important research direction for the design of broadband amplifiers and light sources for optical communication with zero dispersion. Index Terms-Broadband amplifiers, gain characteristics, PbS nanoparticles, PbS/Er co-doped silica fiber.
I. INTRODUCTIONE XPANDING the bandwidth of optical fiber amplifiers and enhancing the gain characteristics can improve the efficacy of communication systems [1], [2]. Erbium-doped fiber amplifiers and other rare-earth-doped fiber amplifiers can achieve high gain in specific wavelength bands. However, the gain bandwidths are usually limited because of the inherent energy-level structure of rare earth (RE) ions [3], [4]. Bi-doped fiber amplifiers exhibit broadband luminescence and amplification. However, the nature of Bi active centers remains controversial and it is difficult to control during the fabrication process. Hence, it is crucial to identify new materials for improving the optical properties of actively doped fibers in the near-infrared band.Recently, nano-semiconductor materials with high quantum efficiency, bandgap tunability, and broad spectral properties have received widespread attention [5], [6]. Compared to other nano-semiconductors, those in the IV-VI group have significant Manuscript