Properties of Ga–La–Na sulphide glasses

A series of Ga–La–Na–S (GLNS) glasses have been investigated as candidate materials for optical fibers operating in the mid-infrared region of 2–5 μm. The GLNS system has been selected as a possible alternative to the Ga–La–S (GLS) system (based around 70Ga2S3/30La2S3) which, due to stability criteria, has proven difficult to fiber draw. The GLNS system was derived by substituting, into the standard GLS system, Na2S in place of La2S3. Seven glasses in total were characterized with compositions containing 0–30 mol% Na2S. Two glasses have been selected that show suitable properties to form a core/clad pair for fiber fabrication. The core glass selected has a 70Ga2S3–10La2S3–20Na2S mol% composition in conjunction with a 70Ga2S3–5La2S3–25Na2S mol% glass as the cladding.