Abstract: Disclosed are laser glasses composed of a Ga--Na--S glasses doped with one or more kinds of activating ions, laser glass fibers comprising a core and a clad wherein the core is composed of the above-mentioned laser glasses of the present invention and optical fiber amplifiers comprising a pumping source, a laser glass fiber and a means for introducing pumping light and signal light into the laser glass fiber wherein the laser glass fiber is the above-mentioned laser glass fiber of the present invention. The laser glasses of the present invention show high radiative quantum efficiency and host glass stability and can be produced easily.

Abstract: Faraday rotation glass having a practically sufficiently large Verdet's constant, which contains 60 to 75 mol % of P.sub.2 O.sub.5, 10 to 20 mol % of Tb.sub.2 O.sub.3 and 10 to 25 mol % of K.sub.2 O and having substantially no platinum inclusion.

Abstract: Disclosed is halide laser glass which comprises cationic components and anionic components. The cationic components are constituted by: Al ions; Zr ions and/or Hf ions; at least one kind of ions selected from the first group consisting of Ca ions, Sr ions and Ba ions; at least one kind of ions selected from the second group consisting of Mg ions, Y ions and alkali metal ions; and Er ions, the cationic components being present within the ranges: Al ions in a range of from 20 to 45 mol %, Zr ions and/or Hf ions in a range of from 0.