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Feature Articles: Optical Fiber Communications
pared with the step index profile.
As an example, simulated and measured bending
loss at 1650 nm as a function of bending radius for
fibers with the trench-index and step-index profiles
Fig�� Fig�� Fig�� Fig�� Fig�� Simulated Simulated Simulated and and measured measured bending bending loss loss at at ����nm ����nm ����nm ����nm ����nm as as a a func� func� func� func� func�
tion tion of of bending bending radius radius for for for fibers fibers with with trench�index trench�index trench�index trench�index trench�index and and step�index step�index step�index step�index step�index
profiles� profiles� profiles� profiles� profiles�
are shown in Fig.7. The bending loss of the fiber with
a trench index profile is lower than that
of the fiber with a step index profile. A
mechanical splice loss between the
fiber and C-SMF is 0.15 dB in average
and 0.03 dB in standard deviation,
which is acceptable for practical use.
V. EASY-HANDLING Ø0.5
-MM OPTICAL FIBER
It has been necessary to simplify the
installation of cables and to reduce
construction time to popularize FTTH.
A fiber with thicker coating than the
conventional fiber with a diameter of
0.25 mm is expected to ease the handling
in installation and connection.
However, commercially available connection
tools and devices for FTTH are
specialized for Ø 0.25-mm fiber.
The schematic of structure for the
easy-handling Ø0.5-mm optical fiber is shown in
Fig.8. Two layers of UV curable resin and a thin layer
of colorant are applied to Ø0.125 mm silica fiber, and
the outer diameter of this fiber is Ø0.25 mm. The
low-bending-loss single-mode fiber
(FutureGuide ® -SR15) is employed as
the silica fiber in order to reduce bending
radius in storage and loss.
The outer surface of this fiber is coated
with colored UV curable resin, and the
final diameter is 0.5 mm. This layer is
designed to be easily strippable from
the Ø0.25-mm fiber but to be stably
attached to the fiber. As a result, the
existing commercially available splice
tools and devices can be applied to the
new fiber. The characteristics of Ø0.
5mm optical fiber are shown in Table 3.
VI. DROP CABLE
In Japan, the typical drop cable wired from an aerial
Fig��� Fig��� Fig��� Fig��� Fig��� Schematic Schematic Schematic of of the the structure structure for for ��� ��� ��� ��� ��� mm mm mm optical optical fiber fiber in� in� in� in� in�
crease crease in in handling� handling� handling�
handling� handling�
China Communications December 2005