Chalcogenide glass host increases gain of 1.3µm fiber amplifiers

A doublecrucible method to fabricate praseodymium (Pr) doped arsenic sulfide chalcogenide fibers for 1.3µm amplifiers has been developed by scientists at NTT OptoElectronics Laboratories (IbarakiKen, Japan). A number of important improvements in Pr:glass properties have been achieved that may make the 1.3µm Pr:doped amplifier more efficient. A gain coefficient of greater than 1 dB/mW is possible in the AsS glass compared to only 0.24 dB/mW for Pr:doped ZBLAN. The AsS chalcogenide system was thermally stable with optical attenuation of only 0.48 and 0.17 dB/m at 1.0 and 1.3 µm, respectively. The refractiveindex difference depended on the sulfur content. The measured difference was 0.6% but differences of more than 4% are reportedly possible, thus allowing high numerical apertures for easy coupling.