An interesting report written in Russian:
D. A. Dvoreckii, V. F. Hopin, A. N. Gur’yanov, L. K. Denisov, L. D. Ishakova and I. A. Bufetov:
“Optical losses in silica based fibers within the temperature range from 300 to 1500 K”,
Science and Education: electronic scientific-technical journal, 5 (2013).