PURPOSE: To improve the emission intensity and stability of a laser by incorporating fluoroalumino zirconate (AZF) containing specified amts. of Er ion as the luminescent center and Yb ion as a sensitizer.

CONSTITUTION: A mixture compsn. of the AZF glass source material is perpared by mixing AlF2, ZrF4, CaF3, MgF2, etc., and adding and mixing desired amts. of ErF3 and YbF3. This compsn. is put in a platinum crucible and molten in an electric furnace in a nitrogen gas atmosphere at about 900°C for about 2 hours. The molten glass is molded to produce a laser glass consisting of AZF containing 8-11cat% Er3+ as the luminescent center and 1-4cat% Yb3+ as a sensitizer. This laser glass is used for 2.7μm emission optically pumped with 0.98μm light.