The Basics of PM Fiber Patch Cords

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Polarization
maintaining (PM) fiber optic patch cord is a kind of special fiber patch cord.
It can be used in many areas. Here’s what you need to know about PM fiber patch
cords if your designs require them.

 

What
Is a PM Fiber Patch Cord?

 

A
PM optical fiber is a single mode optical fiber in which linearly polarized
light, if properly launched into the fiber, maintains a linear polarization
during propagation, exiting the fiber in a specific linear polarization state.
PM fiber patch cord is a fiber optic cable made with PM fiber and terminated on
both ends with high-quality ceramic fiber connectors. PM fiber patch cord is a
base device of optical passive component.

 

Characteristics
of PM Fiber Patch Cords

 

If
the polarization of the input light is not aligned with the stress direction in
the fiber, the output light will vary between linear and circular polarization
(and generally will be elliptically polarized). And the exact polarization will
also be sensitive to variations in temperature and stress in the fiber. The
light shall be coupled at the fiber entrance parallel to the slow axis or to
the fast axis, then the maintaining of the polarization is therefore possible.
It is important to make sure that the polarization of the input light is
maintained. PM
fiber patch cords maintain the existing polarization of
linearly-polarized light that is launched into the fiber with the correct
orientation. PM fiber patch cords also feature low insertion loss, high
extinction ratio, high return loss, excellent changeability over a wide
wavelength range and excellent environmental stability and reliability.

 

Types
of PM Fiber Patch Cords

 

There
are a wide variety of PM fiber patch cords available that support different
data rates and suit various connector types. According to different criteria,
PM fiber patch cords can be categorized into various types. The following is
some detailed information about types of PM fiber patch cords based on 4
different criteria:

 

Classification
by connector type―PM fiber patch cords are capped at both ends with fiber
connectors. FC, SC, LC and ST are the commonly used connector types for PM
fiber termination. According to the connectors on the both ends, there are many
different kinds of PM fiber patch cords, such as LC-FC, SC-FC, or FC-FC PM
fiber patch cords.

 

Classification
by fiber type―PM fiber patch cords are built with polarization maintaining
fiber. To ensure the polarization of both the input and output light in a PM
fiber, several different shapes of rod are used, and the resulting fiber is
sold under brand names such as “Panda” and “Bow-tie”. With different PM fiber,
there are corresponding PM fiber patch cords, such as Panda PM fiber patch
cords and Bow-tie PM fiber patch cords.

 

Classification
by cable type―PM fiber patch cords can also be categorized according to the
cable types. There are mainly three kinds of cable types, 250um bare fiber,
900um loose tube jacket and 3mm loose tube jacket. So based on the cable types,
there are 3 kinds of PM fiber patch cords.

 

Classification
by fiber length―The standard length is 1 meter. It can vary for special
requirements. The length of PM fiber patch cords can be custom made.

 

Applications
of PM Fiber Patch Cords

 

PM
fiber patch cords are often used in polarization sensitive fiber optical systems
for transmission of light that requires the PM state to be maintained. PM
optical patch cord is a special optical component using the properties of
optical fibers specially manufactured so that its transmission parameters can
support a particular application. They have a large number of uses, including
high-data-rate communications systems, polarization sensitive components, and
interferometric sensors. They are also widely used in PM fiber amplifiers,
fiber lasers, high speed communication systems, testing equipment and
instrumentation applications. Area of use of PM fiber patch cords is very broad
and includes equipment such as instrumentation, spectroscopy, aerospace,
medical diagnostics and many other industrial applications.

 

Conclusion

 

Understanding
polarization has become a necessity in today’s fiber optic communication
systems and applications. One must understand how to characterize and handle
the effects of polarization in order to maximize the performances of systems
involving polarization-sensitive devices. PM fiber patch cord is based on a
high precision butt-style connection technique to preserve polarization. It has
many types and applications. Knowing more about it can help you to choose.