Fiber excess length in a cable containing optical fiber ribbons

Authors

  • Satomi Hatano,

    1. NTT Electrical Communications Laboratories, Ibaraki, Japan 319-11
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    • Satomi Hatano received B.S. in Electrical Engineering, Tohoku University in 1972. Joined NTT Communications Laboratories in the same year, and has been engaged in the studies of optical fibers. Presently, he is also involved in the study of high-density optical fiber cables. Senior research Engineer at NTT, and Member, I.E.E.E.

  • Toshinao Kokubun,

    1. NTT Electrical Communications Laboratories, Ibaraki, Japan 319-11
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    • Toshinao Kokubun received B.S. and M.S. in Electrical Engineering, Ibaraki University in 1980 and 1982, respectively. Joined NTT Communications Laboratories in 1982. Engaged in the study of optical fiber cables. Research engineer in the Subscriber Transmission Line Section, NTT Communications Laboratories.

  • Kazuo Hogari,

    1. NTT Electrical Communications Laboratories, Ibaraki, Japan 319-11
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    • Kazuo Hogari received B.S. in Electronics Engineering, Ibaraki University in 1981 and joined NTT Communications Laboratories. Engaged in the study of subscriber optical fiber cables. Research engineer of the Subscriber Transmission Line Section, NTT Communications Laboratories.

  • Yutaka Katsuyama

    1. NTT Electrical Communications Laboratories, Ibaraki, Japan 319-11
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    • Yutaka Katsuyama received B.S. and M.S. in Mechanical Engineering, Kyoto University in 1971 and 1973, respectively. Joined NTT, Communications Laboratories in 1973. Engaged in the study of optical fiber strength, fiber coating and fiber cabling, and the development of graded index fibers and single mode fibers. Senior research engineer. Ph.D. Recipient of I.E.C.E. Award in 1980. Member, American Optical Society.


Abstract

A cable containing optical fiber ribbons in a loose tube is promising for high-density, multifiber and economical communication. This paper discusses the influence of excess fiber length.

Assuming that the optical fiber excess length (the difference between the lengths of the optical fiber and its container) causes the optical fiber to bend, the relationship between the excess length and sinusoidal bending radius has been obtained. It was found that the optical losses due to the sinusoidal bend of a graded-index multinode fiber with core and outer diameter of 50 and 125 μm respectively, were inversely proportional to the square of the minimum radius of curvature. Also, the loss characteristic is the same as that in case of the uniform spiral bend. Based on these results, the method of estimating the optical losses due to the excess length was obtained. It was confirmed that the measured optical loss agreed with the estimated loss.

It was found that the excess length ratio β should be restricted between −0.05 and 0.2 percent to minimize the optical losses and fiber failure probability.

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