Fictive temperature measurement of single-mode optical-fiber coreand cladding

The fictive temperatures of single-mode optical-fiber core, along with its inner and outer cladding, were measured using an infrared (IR) reflection method on the fiber cross-sectional surface. To allow for usage of a larger IR beam size than the diameter of the fiber core, the cross-sectional area of the fiber was increased by slicing the fiber at an oblique angle, along approximately 3° off the fiber axis direction. The magnitude of the fictive temperature was estimated from the IR peak wavenumber-fictive temperature relation obtained for bulk glasses with the same compositions. The observed fictive temperature was in the range of 1150~1300°C for the core, 1450~1550°C for the inner cladding, and 1620~1660°C for the outer cladding and exhibited good correlation with the fiber cooling rate