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.