Abstract: A Ge--Ga--S-based glass composition having light amplifying characteristics and an apparatus for optical communications using the glass composition are provided. The present invention includes a sulfur-poor Ge--Ga--S based host glass which includes less S than compositions on the composition line of GeS.sub.2 --G.sub.2 S.sub.3 on the ternary phase diagram of Ge--Ga--S, and a rare earth active material doped on the host glass for luminescence and light amplification. Ga of no more than about 10 mol % is included in the host glass. Also, Pr.sup.3+ ions are used as the rare earth active material. Furthermore, for stable vitrification and a blue shift of a short wavelength absorption band, a vitrification stabilizer such as Br and I is added to the host glass.

Abstract: A Ge--Ga--S-based glass composition for performing an optical amplification and an apparatus for optical communications using the same are provided. In the glass composition according to the present invention, an active material for performing luminescence and optical amplification operations is added to the Ge--Ga--S host glass and a transition metal ion moving the distribution of optical amplification gains is added in a range from 0.01 mole % to 0.2 mol %.