The Way to Choose Suitable Patch Cable for Optical Transceiver?

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People are always amazed by the fast
development of optical communication. Fiber optic transceiver, a small-size but
important component, can best represent the advancing of the optical
communication industry. The form factor of optical transceiver has changed from
GBIC for Gigabit Ethernet to SFP+ for 10GbE, QSFP+ for 40GbE and CFP or QSFP28
for 100GbE. It is not difficult to tell the differences among these
transceivers. However, users may feel confused about the patch cable which is
used to connect optical transceiver to the telecommunication network. This post
will introduce how to choose the suitable patch cable for optical transceiver
from the aspects of transmission media, transmission distance & rate, and
interface.

 

Optical Transceiver and Patch Cable
Overview

Optical transceiver or optical
transmitter and receiver (shown in the following picture) is a device that uses
fiber optics technology to send and receive data. The transceiver has
electronic components to condition and encode/decode data into light pulses and
then send them to the other end as electrical signals. To send data as light,
it makes use of a light source, which is controlled by the electronic parts,
and to receive light pulses, it makes use of a photodiode semiconductor. There
are different types of transceivers for different Ethernet networks, such as 1G
GBIC, 10G SFP+, 40G QSFP+, etc.

 

A patch cable or patch cord is an
electrical or optical cable used to connect one electronic or optical device to
another for signal routing. It is composed of electrical or optical cable
terminated with connectors at each end. Optical patch cable is the most popular
cable widely applied in data center and telecommunication networks. They can be
differ from different connector types (see in the image below), like LC, SC, ST
and FC, etc, different core diameters, like single-mode optical patch cable,
multimode optical patch cable, and different fiber cable structure, like
simplex optical patch cable and duplex optical patch cable.

 

Factors to Consider When Choosing patch
cable for Optical Transceiver

Transmission Media

As we all know, there are two kinds of
transmission medias in the network—fiber optic and copper. Therefore, based on
these two media types, transceivers can be divided into fiber optic based
transceiver and copper based transceiver. Copper based transceiver, such as
1000Base-T SFP and 10GBase-SFP+, which usually has a RJ45 interface, can achieve
connection to the network with the use of cat5/6/7 patch cables.

 

Compared to copper based transceiver,
patch cable choices for fiber optic based cable are more complicated.
Generally, fiber optic patch cable comes in two types: single-mode fiber patch
cable and multimode fiber patch cable, and each type can be used in different
applications. Single-mode fiber patch cable can be further classified into OS1
and OS2, while multimode fiber patch cable can be further divided into OM1.
OM2, OM3 and OM4. Single-mode fiber optic cable has a small diameter core that
allows only one mode of light to propagate, so it is suitable for long
distances data transmission. On the contrary, multimode fiber optic cable has a
large diameter core that allows multiple modes of light to propagate, thus it
is available for short distance data transmission. Typically, if the
transmission distance is shorter than 500 meters, multimode fiber optic cable
is suggested, otherwise, the single-mode fiber patch cable is a better choice.

 

Transmission Distance and Rate

It is known that the transmission rate
will decrease as the transmission distance increases. Single-mode fiber patch
cable can provide higher performance for different rates in both short and long
distances, but it will cost more. When it comes to short transmission distance,
it’s better to choose multimode fiber patch cable. As we have mentioned above,
multimode fiber patch cable can be classified into OM1, OM2, OM3 and OM4.

 

OM1 patch cable supports 10 Gigabit
Ethernet applications at 33 m, but is usually used for 100 Megabit Ethernet
applications, while OM2 patch cable is standardized to support 10 Gigabit
Ethernet applications at 82 m, but is usually applied for 1 Gigabit Ethernet
applications. OM3 patch cable is commonly used to run 10 Gigabit Ethernet applications
at 300 m, though it has been improved to work with 40G and 100G Ethernet
applications if using a MPO connector. OM4 patch cable is optimized to support
10 Gigabit Ethernet at length up to 550 m, and 100 Gigabit Ethernet at 150 m
with MPO connectors. The different performances of multimode fiber patch cable
types are shown in the table below.

 

Transceiver Interface

Transceiver interface is also an
important factor when selecting patch cable for transceiver. Most optical
transceivers have two ports, one port for transmitting and one port for
receiving, so duplex SC and LC interfaces are usually employed. However, for
BiDi transceiver which has only one port for both transmitting and receiving,
simplex fiber patch cords will be used. For 40G QSFP+ transceivers, which often
use MPO/MTP interfaces, multimode fiber patch cords attached with MPO/MTP
connectors will be deployed.

 

Conclusion

Optical transceiver and patch cable are
both vital components in telecommunication networks. Without any of these two
devices, the network connection can be achieved. Only matched optical
transceivers and patch cables can provide better performance. Through the
information that we have mentioned above, hope you can choose the suitable
patch cable for your optical transceiver.