ECOC 1975 - ECOC 2013

STEP INDEX TYPE OPTICAL FIBER CABLE
70
Hiroshi Murata, Shozo Inao and Yoshikazu Matsuda
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1. Introduction l )
A low-loss optical fiber has been developed and its application to cable
is now being worked out in many countries. The following are the conditions
required of the optical cable. (1) It can be handled in the same
way as the ordinary communication cable. (2) It permits field jointing.
(3) It has transmission properties fit for specific uses. The optical
cable is expected to be used, first of all, as city junction cable and
intra-office cable and then as short haul toll cable, trunk toll cable
and city distribution cable in that order .
Line Repeater Trans. Attenuation
length spacing capacity const.
City junction
cable
5 - 8 km 5 - 8 km
6 - 100
Mb/s
-
Toll cable 50 - 500km 4.5-8 km
32 - 400
Mb/s
5 - 8 dB/km
4 - 8 dB/km
The table above shows an example of the conditions under which the cable
will be used in Japan. We have succeeded in test production and installation
of an optical cable that meets the conditions required of the city
junction cable which will possibily be the first practical application
for the optical fiber cable.
2. Design of optical fiber cable 2 )3)
2.1. Coating of optical fiber
The coating of optical fiber is required from the standpoint of reinforcement,
protection and crosstalk, and coating material and its
outer diameter must be determined from the following consideration:
(1) stress given to the fiber during cable making process and installation
(tension, bend, torsion, etc.) must not exceed its breaking stress;
(2) Coating material and fiber must adhere to each other to prevent
local stress concentration in the fiber; and (3) Loss increase due to
microbend must be small. We trial-manufactured coated fibers as shown
in Fig. 1 (A)-(C) and found that the construction which best filled the
requirements of (1)-(3) was (A), material Nylon and outer diameter 0.5 ­
1.0 mm.
2.2. Stranding and sheathing
In stranding coated fibers, the cable construction must be fixed taking
the following conditions into account: (1) To reduce the mechanical
H. Murata, S. Inao and Y. Matsuda are with The Furukawa Electric Co., Ltd.
Marunouchi, Chiyodaku, Tokyo 100, Japan.