Advanced materials for fibre and waveguide amplifiers

Recent research into optical fibre and waveguide amplifiers has been characterized by steady progress. Advances in the lowest fibre loss 1.5 μm telecommunications window, where newly installed optical networks operate, include erbium-doped materials with flatter gain spectra and planar amplifiers in a broad range of materials including oxide glasses, dielectric crystals and semiconductors. At 1.3 μm, substantial improvements have been made in praseodymium-doped fluoride fibre amplifiers and chalcogenide glasses have shown promise for enhanced gain efficiency.