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Low-Count Aerial Optical Fiber Cable Capable of Mid-Span
Branching Requiring No Special Tools

1.

INTRODUCTION

With the growing demand for optical communications inrecent years, demand for installation of optical cables insubscribers’ premises is increasing. In an access network, a low-count aerial cable containing eight to twelve
fibers is used to connect a multi-count aerial cable, fromwhich the low-count cable being branched off, with a subscriber drop cable. Conventional cables used for this purpose, however, raise problems such that dedicated tools
are needed for making access to the fiber at intermediate
points, and that loss increase is generated when thefibers are taken out.
Accordingly, we have recently developed a low-countaerial cable accommodating eight fibers that allows for
mid-span branching at any intermediate points after cableinstallation using an off-the-shelf cutting nipper.

2.

electric poles, the cable can be easily fixed using hangers
without resort to cutting the suspension member to fix thecable using insertion-type strain clamp fittings and thelike.

3.

CHARACTERISTICS

Table 1 shows the loss increase during the mid-spanbranching work. The maximum loss variation is 0.1 dB orless for any process, demonstrating superior characteristics.
Table 2 shows general characteristics including transmission, mechanical and temperature characteristics,
exhibiting superior performance.

Suspension member

PE sheath

Two 4-ﬁber QS ribbons（FlexiWave）

FEATURES

2.1

Mid-Span Branching Enabled Structure
Requiring No Special Tools
In order to split the cable sheath without bending the cableso as not to cause loss increase, it is advantageous to split
the sheath by making a longitudinal cut using a tool.
Furthermore, to assure damage-less separation offibers at the time of sheath splitting, it is useful to provide
a kind of additional filler between the sheath and the fiberthat does not stick to either of these, and to give a cut
against the filler.
Taking into consideration the above, a cable structure
has been adopted such that two circular fillers are disposed oppositely at the both ends of the optical fiber
array and these are sheathed in block together with twostrength members. Figure 1 shows a cross section of thecable.
As for the tool for making a longitudinal cut on thecable, angular tooth cutting nipper was adopted considering its widespread availability and cost.
Figures 2 through 6 show every step of mid-spanbranching procedures for the cable.
2.2 Cable Excess Length
A slack structure has been adopted for the cable developed here, where the cable main body is intermittently
joined with the suspension member to provide an excess
length over the suspension member. Thus, at run-throughConnection part

Figure 1NotchFiller

Strength member

Cable cross section.

Angular tooth cutting nippersplitting the connecting part

Figure 2

Cutting the connection part using a cutting nipper.

Furukawa Review, No. 33

200814

Low-Count Aerial Optical Fiber Cable Capable of Mid-Span Branching Requiring No Special Tools

Angular tooth cutting
nipper splitting the sheath

Figure 6 Separating the 4-fiber QS ribbon.

Table 1

Typical loss increase during branching work.
Max. loss variation
Measurement wavelength: 1550 nm
Sampling time: 1 ms

Process

Figure 3

Separating the sheath along the notch using a cutting
nipper to make an initial cut approx. 50 mm in length.

Connection part cutting＜0.1

Sheath separation using nipper＜0.1

Sheath tearing off by hand

＜0.1

Sheath and filler removal＜0.1

QS ribbon separation＜0.1

Table 2
Tear by hand

Cable characteristics.

Test item

Conditions

ResultTransmission
characteristics

1310 nm＜0.34 dB/km

1550 nm＜0.25 dB/km

Tension2500 N＜0.1 dB

Squeezing

R=250 mm, 90°,
700 N, 4 cycle＜0.1 dB

Mechanical
Bendingcharacteristics
Measurement Lateral pressure
wavelength:
Twisting
1550 nm

Figure 4

Tearing off the sheath by hand for a required length.

Figure 5 Removing the sheath and filler.

＜0.1 dB＜0.1 dB±90°/m×1 cycle＜0.1 dB

Impact

300 g・φ20 mm×1 m＜0.1 dB

Vibration

Span 35 m, amplitude:
25 cm, 2 Hz x 1 million cycle＜0.1 dB-30～70℃, 10 cycle＜0.1 dB/km

Temperature characteristics

4.

R=30 mm x 10 cycle
1200 N/25 mm×1 min

CONCLUSION

A low-count aerial optical fiber cable capable of mid-spanbranching using a low-cost, easily available tool of angular tooth cutting nipper has been developed. Use of thiscable developed here can flexibly respond to demands
for opening up optical communications, so that it isexpected that the cable will significantly serve to implement efficient optical distribution networks.

For more information, please contact:
Telecommunications Engineering Dept.,
Telecommunications Co.		 TEL: +81-3-3286-3426
FAX: +81-3-3286-3190

Furukawa Review, No. 33

200815