Commissioning/application notes
EK110x, EK15xx
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Version: 3.6
Single mode
Single-mode fibers have a very thin core (9 µm) and therefore conduct only a single mode of the light used,
with high signal quality and virtually without mode dispersion. They are only available as step index fibers.
Due to the high signal quality they are suitable for large transmission bandwidths > 10 GHz*km and
distances > 50 km. The refractive index profile of single-mode fibers is dimensioned such that the multipath
propagation (intermodal dispersion), which is a problem with multi-mode fibers, is omitted – the signal light
propagates in a single-mode fiber only in a single guided fiber mode, hence the designation ‘single-mode’.
This makes considerably larger transmission distances and/or bandwidths possible, and the limiting effect
that arises next is the color distortion of the transmitted mode.
Multimode
Multimode fibers are manufactured as step index or graded index. Step index multimode fiber cables are
suitable for transmission bandwidths up to 100 MHz*km and distances up to 1 km. Graded index multimode
fiber cables with core diameters between 50 and 62.5 µm reach transmission bandwidths > 1 GHz*km and
ranges > 10 km. Multimode means that the core of the optical fiber cable is thick enough to enable several
light modes to propagate reflectively in the cable.
5.2.1.2
Application with EK1501 and EK1501-0010
The EK1501 / EK1501-0010 is intended for application with optical fiber cables with the following
characteristics:
• SC duplex connector
• EK1501: Duplex multimode 50/125 µm or 62.5/125 µm (inner/outer core diameter). The use of both
diameters is possible. However, the use of 50/125 µm is recommended due to the lower attenuation.
• EK1501-0010: Duplex single-mode 9/125 µm (inner/outer core diameter). A typically usable cable can
be manufactured according to the specification IT-T G.652.D (0.4dBm/km at 1300nm).
Note
Recommended connectors
The use of SC/PC connectors is recommended for connecting to the EK1501/
EK1501-0010. The advantage of the "PC" (physical contact) version of this connector is the
crowned end face, which allows the region of the fiber core that is relevant to transmission
to be optimally joined when the connector is pushed together. Other versions include, for
instance, the SC/UPC (ultra-polish PC), SC/HRL (high return loss) and the SC/APC plug
(angled physical contact). An additional feature of these connectors is that light that is re-
flected by the connector's end face, which is at an angle of about 8° to the fiber axis, is re-
fracted from the core by the cladding glass into the air. This avoids interference with the
data transmission, optimizing the core size of the back-scatter.
In optical fibers the wavelengths 850 and 1300 nm are usually used for data transfer. Commercially available
fiber-optic cables are usually optimized for application in one of these ranges, since signal attenuation is
frequency-dependent (like in copper cable), so that large ranges of several km can be achieved for the
respective wavelength. Fiber-optic cables in the 1300 nm window generally have lower attenuation than
cables in the 850 nm window.
In the EK1501/EK1501-0010 a transceiver with the wavelength of 1300 nm is used.
Note
Range and bandwidth product
Optical fiber cables are available in different qualities from reputable manufacturers. One of
the relevant parameters for the user is the frequency-dependent bandwidth product of a ca-
ble, specified in [MHz*km]. The greater the bandwidth product, the lower the attenuation,
and therefore the larger the range that can be achieved with this cable (see ITU-T G-651).
For achieving the maximum range with the EK1501 / EK1501-0010, optical fibers with a
maximum bandwidth product of 1300 nm should therefore be used; we recommended us-
ing class OM2 optical fibers (EN50173:2002). Standard optical fiber cables have a mini-
mum bandwidth product of 500 MHz*km at 1300 nm, higher-quality cables are suitable for
distances > 500 m over > 1000 MHz*km. In order to achieve the maximum range, the de-
vice to which the EK1501/EK1501-0010 is connected must also support such ranges.
