Abstract: Disclosed herein is a low phonon energy glass and a fiber made therefrom. e glass includes the following components given in mol percent:______________________________________ germanium 0.1-30 arsenic 0-40 X 0.01-20 Y 40-85 ______________________________________wherein X is selected from the group consisting of gallium, indium and mixtures thereof wherein Y is selected from the group consisting of selenium, and mixtures of selenium and up to 50% of sulfur substituted for selenium and the glass also contains 0.001-2 weight percent of a rare earth, based on the weight of said components. The fiber has a minimum loss of less than 5 dB/m.

Abstract: Disclosed herein is an amplification method, an optical glass amplifier, a laser based on the amplifier and an amplification optical communication system, all based on a limited length of a single-mode glass fiber made from glass having phonon energy of less than about 350 cm.sup.-1 and doped with dysprosium. The glass includes 0.1-30 mol % germanium, 0-40 mol % arsenic, 0.01-20 mol % X, 0.01-20 mol % Y, and 0.001-2 weight % dysprosium, wherein X is selected from the group consisting of gallium, indium and mixtures thereof selenium; and wherein Y is selected from the group consisting of selenium, and mixtures of selenium and up to 50% of sulfur. The system includes a coupler, a silica-based signal fiber carrying the optical signal that is to be amplified in communication with said coupling means, a pump light source in communication with the coupler, an amplifier in communication with the coupler at one end and another silica-based fiber joined to the amplifier at its other end.