The thermal characteristics of excess signal loss in unjacketed multimode optical fibers are examined experimentally and theoretically. An unjacketed optical fiber is repeatedly wound under several different tensions and excess optical loss is measured at various temperatures using an Optical Time Domain Reflecto-meter. It is found that excess optical loss increases below 0°C. The fiber buckling model, used in the thermal analysis of jacketed fibers, is considered for the theoretical evaluation of fiber buckling caused by the mismatch of thermal expansion coefficients between the fiber and coating. The mode coupling theory is used to analyze microbending of the fiber caused by lateral shrinkage of the coating and Young's modulus increase at low temperature in the presence of initial fiber imperfections. A comparison of the data and theoretical results indicates that imperfections at the crossovers are the prime contributor to excess loss at low temperature. Results of the data show that excess optical loss at low temperature increases with winding tension.

Date Published: 1 January 1987
PDF: 9 pages
Proc. SPIE 0842, Fiber Optics Reliability: Benign and Adverse Environments, (1 January 1987); doi: 10.1117/12.968174

Published in SPIE Proceedings Vol. 0842:
Fiber Optics Reliability: Benign and Adverse Environments
Dilip K. Paul, Editor(s)