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

The change in the absorption loss relative to room temperature of the infrared (IR)-transmitting Ge15As35Se((50-x))Te-x glass fibers in the temperature 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 greater than or equal to 40 degreesC. This is mainly attributed to thermally activated 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 wavelength region of 5-11 mum, the loss was mainly due to free-carrier absorption, Beyond lambda greater than or equal to 11 mum, multiphonon absorption 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 than or equal to 80 degreesC.