Very large temperature-induced absorptive loss in high Te-containing chalcogenide fibers

The change in the absorption loss relative to room temperature of the infra red (IR)-transmitting Ge15As35Se((50-x))Te-x glass fibers in the temperatur e range of -110 degreesC less than or equal to T less than or equal to 110 degreesC was investigated. The attenuation increased significantly at T gre ater than or equal to 40 degreesC. This is mainly attributed to thermally a ctivated free carriers associated with the semimetallic character of the Te atom. For lambda less than or equal to 4.2 mum, the loss due to electronic and free-carrier absorption was strongly affected by temperature. In the w avelength region of 5-11 mum, the loss was mainly due to free-carrier absor ption, Beyond lambda greater than or equal to 11 mum, multiphonon absorptio n dominated the loss spectrum at T less than or equal to 60 degreesC while free-carrier absorption contributed mainly to the total loss at T greater t han or equal to 80 degreesC.