The influence of annealing at 1000 °C on the absorption and luminescence spectra of chromium in aluminosilicate and gallium silicate fibers at temperatures of 77 and 300 K is investigated. The spectra of initially weak luminescence with a maximum at 1100 nm and a quantum yield of approximately 10<sup>−5</sup> at 300 K shift to the 790–880-nm range in annealed fibers. After annealing the quantum yield increases by as much as 10%. The luminescence lifetime is found to be approximately 20 μs. The luminescence changes are explained by a rearrangement of the nearest environment and recharge of chromium ions (Cr<sup>4+</sup> to Cr<sup>3+</sup>). The results obtained hold promise for the creation of tunable and ultrashort pulse fiber lasers.
© 2003 Optical Society of America
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
(300.6280) Spectroscopy : Spectroscopy, fluorescence and luminescence
Vladislav V. Dvoyrin, Valery M. Mashinsky, Vladimir B. Neustruev, Evgeny M. Dianov, Alexei N. Guryanov, and Andrei A. Umnikov, "Effective room-temperature luminescence in annealed chromium-doped silicate optical fibers," J. Opt. Soc. Am. B 20, 280-283 (2003)