Bismuth-doped optical fibers and fiber lasers for a spectral region of 1600-1800 nm.

Bismuth-doped optical fibers and fiber lasers operating in 1625-1775 nm range have been developed for the first time to the best of our knowledge. Now the existing bismuth-doped lasers, including the result presented in this Letter, can cover O, E, S, C, L, and U telecommunication bands. In addition, new data on the nature of the bismuth-related active center were obtained and discussed.