Optical fiber loss increase due to hydrogen and long-term loss stability for optical fiber cables

• Published in: Electronics & communications in Japan. Part 2, Electronics Vol. 69; no. 5; pp. 1 - 9
• Main Authors: Noguchi, Kazuhiro, Shibata, Nori, Uesugi, Naoshi, Ishihara, Koushi, Negishi, Yukiyasu
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 1986
• ISSN: 8756-663X; 1520-6432
• DOI: 10.1002/ecjb.4420690501

Recently, it has become clear that the long‐term loss of an optical fiber increases if the fiber is exposed to hydrogen. This phenomenon indicates that the loss in the optical fiber installed in a cable can increase if for some reason hydrogen is generated in the fiber cable. Therefore, this phenomenon is important for reliability design consideration. When the optical communication system with the 1.3 μm band is in actual use and the one with the 1.5 μm band is nearing its preparation for actual use, it is especially important to understand clearly the guarantee of long‐term reliability of an optical fiber cable and prevention of the effects of hydrogen. In this paper, the loss increase characteristics are formulated for optical fiber with germanium as an only dopant placed in a hydrogen atmosphere. The formulation is done from the results of increased temperature tests in hydrogen. From the formula, an allowable level of hydrogen pressure in the cable is calculated such that the loss increase of the fiber is kept below a specified value. It is also shown that the loss increase is sufficiently suppressed for practice by preventing water leakage into the cable.