Specialty fibers for optical amplifiers in communications

Various solutions are explored to extend the bandwidth with flat gain of optical amplifiers and to open up new bands for efficient amplification. Many solutions require non-silica fibers, e.g. fluoride fibers or heavy metal oxide fibers of different kinds like tellurite or the newly developed antimony silicate fibers. The main properties of such fibers and their impact on system performance in the S, C and L-bands are described.