Polarization Maintaining Patchcord and Patch Cable: Features, Types, and Applications

Standard fibre patch cables are well-known in our lives, but Polarization Maintaining Patch Cable also comes in a variety of special forms, such as mode conditioning cables and fibre loopbacks. These customised fibre patch cables are often utilised for specific applications.

Function of PM Patch Cables

In the fibre optic industry, polarisation maintaining fibre is a single-mode fibre that can maintain linear polarisation light propagation throughout the transmission inside the fibre. As long as the light is launched linearly into the fibre, its polarisation along the fibre path remains constant. PM patch cable is a fibre optic cable made out of PM fibres and high-quality ceramic fibre optic connectors. PM patch cables feature the following characteristics: low insertion loss, high extinction ratio, high return loss, excellent changeability across a wide wavelength range, and outstanding environmental stability and reliability.

How Do I Choose PM Patch Cables?

Connector

Polarization Maintaining Patchcord, like normal fibre optic cables, commonly uses LC, SC, FC, and ST connections. Connectors on both ends of the cable may be identical or different, such as LC-LC or LC-SC connectors. The connector ends are closed for improved protection because the PM connectors are designed to be more sophisticated.

All PM fibre patch cables employ PM fibres. However, PM fibres can vary depending on the curvature of the inner rod. This unique rod ensures that input and output light are linearly polarised in the fibre.

Cable Jacket

PM fibre patch cables can come with or without a cable jacket. PM cables are classified into three types: bare fibre (250μm), loose tube jacket (900μm), and loose tube jacket (3mm).

Length

The usual cable length for PM fibre patch cables is one metre. If different lengths are necessary, the cable can be customised accordingly.

Where Can I Use PM Patch Cables?

PM fibres, which are normally employed to guide linearly polarised light from point to point, can be utilised for a variety of unique applications in optical sensors, telecommunications, and sensor research. Polarisation Maintaining Patch Cable is particularly beneficial for polarisation-sensitive fibre optical systems that require optical light to remain linear. PM fibre patch cables can be used in conjunction with interferometric sensors, integrated optics, and fibre amplifiers in high-speed and coherent telecommunications.

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Get to Know All about PM Patch Cables

You may learn about LC fiber patch cables or MTP/MPO fiber cables while talking about fiber optic patch cables. Apart from these cables, there are some special fiber patch cables, such as polarization maintaining patch cable and mode conditioning patch cables that have been introduced in the previous article.

PM Patch Cables

At first, let me check the basic definition of the PM patch cables. On a high precision, the butt-style connection technique is polarization-maintaining the isolator is based. By using male connectors with a positioning key and a bulkhead female receptacle with a tight tolerance keyway the PM axis orientation is maintained, and hence ensures good repeatability in extinction ratios and insertion losses.

Need of PM Patch Cables

Stresses are induced in the fiber when a normal fiber is bent or twisted and the polarization state of light will be changed by the stresses traveling through the fiber. The final output polarization varies with the change in temperature or position of the fiber.

Polarization maintaining circulator is developed to solve this problem. For two perpendicular polarizations traveling through the fiber, inducing a difference in the speed of light will make these fibers perform. Within the fiber, this birefringence creates two principal transmission axes which are known as the fast and slow axes of the fiber.

Provided the input light into a PM fiber is linearly polarized and orientated along with one of these two axes, then from the fiber, the output light will remain linearly polarized and aligned with that axis, even when it is subjected to external stresses. To maintain polarization to at least 30dB at 1550 nm a one-meter-long connector’s patch cord constructed with PM fiber should be properly used. How well a PM fiber maintains polarization will depend on the input launch conditions into the fiber. The alignment between the polarization axes of the light with the slow axis of the fiber is the most important factor.

Conclusion

For transmission of light needing the PM state to be maintained, in polarization-sensitive fiber optic systems PM patch cables are used widely. With various connector types, many companies provide polarization-maintaining patch cables.