Judging from its structure, patch cord seems to be too simple. But actually, it plays a really important role in the overall network performance whose main problems are caused by patch cord performance. Thus, understanding fiber patch cord performance comes as the priority.In order to have an in-depth understanding of fiber patch cord performance, this text will be spread from two aspects: the perfect patch cord and polishing conditions.

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Fiberstore (FS.COM) | Understanding Fiber Patch Cord Performance
With each passing day, fiber optic has become increasingly affordable, widely used for high data-rate
systems such as FDDI, multimedia, ATM, or any other network that requires the transfer of large,
time-consuming data files. As one of the most basic elements consisting of fiber optics in optical
networks, fiber patch cord, or fiber optic patch cable and fiber optic jumper, composes of a fiber
optic cable capped with a connector on each end. (In this sense, fiber patch cord can be classified by
the connector types, like LC fiber cable, SC fiber optic cable, MTP/MPO cables, etc..). Judging from
its structure, patch cord seems to be too simple. But actually, it plays a really important role in the
overall network performance whose main problems are caused by patch cord performance. Thus,
understanding fiber patch cord performance comes as the priority.
In order to have an in-depth understanding of fiber patch cord performance, this text will be spread
from two aspects: the perfect patch cord and polishing conditions.
“Perfect Patch Cord”
When a patch cord made by a mated pair of connectors has near zero insertion loss and a relative
power loss, then it’s called perfect patch cord whose performance should be in accordance with fiber
splicing loss that is on the order of 0.02dB. It needs to meet these requirements: insertion loss
<0.05dB and return loss >58dB.
 Notices on Making “Perfect Patch Cord”
To make a “perfect patch cord”, the endface has to be kept clean, meaning that cleanliness of the
production line and the cleaning technique are very important. Besides, the endface geometry of the
ferrule must be controlled and the proper polishing must be operated.
As for loss reduction, it’s advised to properly align the fiber cores within the ferrules of two mated
patch cords. The main factors that influence core alignment are ferrule inner diameter, ferrule
concentricity, and ferrule outside diameter (OD). Understanding all relevant parameters and putting
them under control are essential in making a “perfect patch cord” which must have sub-micron
connector concentricity. The following figure shows the relation between insertion loss and
connector concentricity.
Understanding Fiber
Patch Cord
Performance

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Fiberstore (FS.COM) | Understanding Fiber Patch Cord Performance
 Notes on Testing “Perfect Patch Cord”
A reference cable is required to test a “perfect patch cord”. This cable should be at least at least
comparable to the “perfect patch cord”. In order to get the accurate measurements, other parameters
also need to be controlled while testing “perfect patch cord”, during which a high quality adapter is
used to insure a consistent insertion loss.
Polishing Connectors
While polishing connectors, the endface on microscopic grits has to be grounded to
remove excess epoxy from the surface and scratches from the fiber endface, as well as shaping the
ferrule and glass.
Most of the current ceramic ferrules are pre-domed. For instance, the endface is shaped to have an
optimum radius of curvature (ROC) and the as-small-as-possible apex offset (AO), as shown below.
Apex offset is an offset of the apex point of ROC. In such case, the polishing must use a polishing
grit hard enough to remove the epoxy from the ferrule and the scratches on the fiber endface, but not
hard enough to significantly alter the ferrule geometry. If a ferrule is not pre-domed, the proper
geometry must be formed through extended polishing.

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Fiberstore (FS.COM) | Understanding Fiber Patch Cord Performance
 Polishing Process
Polishing process is done as followings: firstly to remove epoxy from the ferrule front surface, then
form or keep the dome, and finally to shine the fiber surface. Depending on the polisher and
connectors, an optimization must be made on the polishing pressure, time, and speed.
 Polishing Inspection
After finishing polishing, a microscope with magnification of at least 400x is used for visual
inspection of scratches and damages. A “perfect patch cord” isn’t allowed to have any visible scratch
on the fiber endface. Scratches through the fiber core can not only affect optical performance, but
also damage any other fiber endface they contact. For these reasons, scratches need to be minimized.
In order to guarantee optimal performance, it is not only important to adhere to the polishing
procedure, but also to the cleaning procedures. Once the fiber surface is clean, scratch-free, and
confirmed to have endface geometry within specifications, insertion loss and return loss should fall
into expected specification.
Conclusion
By understanding and controlling factors that have effects on patch cord performance, it’s possible to
build a “perfect patch cord” having an insertion loss equal to that of a fusion splice (near zero
insertion loss). Fiberstore, as a professional fiber patch cord manufacturer, supplies various patch
cords of high quality at low prices, like LC to SC fiber patch cable available at different lengths and
in single-mode and multi-mode versions. For example, the 1m LC UPC to SC UPC 10G 50/125

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Fiberstore (FS.COM) | Understanding Fiber Patch Cord Performance
OM3 Duplex Patch Cord at Fiberstore just costs you US$ 2.60, much less than that’s offered by other
suppliers, say $22.99 at CABLES TO GO.
Contact Us
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Tel: +44 2081441980
Notice: This document is for informational purposes only and does not set forth any warranty, expressed or
implied, concerning any equipment, equipment features, or service offered or to be offered by Fiberstore.
Fiberstore reserves the right to make changes to this document at any time, without notice, and assumes no
responsibility for its use. This information document describes features that may not be currently available.
Contact a Fiberstore sales team for information on feature and product availability.
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