Bi-doped glass optical fibers: Is it a new breakthrough in laser materials?

It has been shown recently, that Bi-doped glass optical fibers are a very promising active laser medium. Luminescence of Bi-doped glasses takes place in a spectral region of 1150–1500 nm, where no efficient fiber lasers (or any other efficient lasers) exist. The glasses have very broad luminescence bands (200–400 nm) and long lifetime (200–700 μs). The Bi absorption bands are situated in a spectral region of 500–1100 nm where long-lived high-brightness laser diodes developed for the pumping of lasers and amplifiers are available. Besides, strong luminescence has been observed in a variety of glass compositions. In this paper the recent results on the new laser material – Bi-doped glasses and optical fibers are reviewed. First, luminescence properties of various Bi-doped glasses are discussed. Then we describe the Bi-doped silica-based optical fiber fabrication and the absorption and luminescence properties of the fibers. At last some results on Bi-doped fiber lasers and their applications are presented.