Thermally Induced Reversible Changes in the 7200 cm^–1 Absorption Band in a Fiber Light Guide with a High Concentration of OH Groups in the Core

For a multimode optical fiber, whose core is formed by quartz glass of the KU-1 type with a high content of hydroxyl groups, the dynamics of the reversible (recoverable) change in the optical absorption of these groups near 7200 cm^–1 when the light guide is heated to 1050°C, are studied. Based on the decomposition of the absorption band into spectral components at different temperatures, assumptions are made regarding the structure of absorption centers related to the OH groups.