Tag Archives: fiber optic patch cable

Basic Things To Know About PM Patch Cables

Standard fiber patch cables are widely discovered in our life, but fiber patch cables also have other special types, such as the mode conditioning cables, fiber loopbacks, etc. These special fiber patch cables are usually used for some particular applications. In this article, we will mainly introduce the basic knowledge of PM (polarization maintaining) patch cables.

PM-patch-cable

Function of PM Patch Cables

In fiber optic industry, polarization maintaining fiber is a single-mode fiber that can maintain a linear polarization light propagation during the whole transmission inside fiber. As long as the light is linearly launched into the fiber, its polarization in the fiber path will not change. PM patch cable is a fiber optic cable consisting of PM fiber and high-quality ceramic fiber optic connectors. With the special polarization maintaining function, PM patch cables have the characteristics of low insertion loss, high extinction ratio, high return loss, excellent changeability over a wide wavelength range and excellent environmental stability and reliability.

How to Choose PM Patch Cables?

PM patch cables have various types according to different classification bases. To choose the right type of PM fiber patch cable, you may consider the following aspects.

Connector

Similar to standard fiber optic cables, the common connectors for PM fiber patch cables are LC, SC, FC and ST types. Connectors on both ends of the cable can be identical or different, such as LC-LC or LC-SC connectors. The special part is that connector ends are capped for better protection since the PM connectors are made to be more sophisticated.

Fiber

PM fiber patch cables all use the PM fibers. However, PM fibers can be different according to different shapes of the inside rod. This special rod can ensure the linear polarization of input and output light in the fiber. The following picture shows the examples of “Panda” and “Bow-Tie” styles of PM fiber.

PM-fiber

Cable Jacket

With or without cable jacket are both common for PM fiber patch cables. Generally speaking, there are three types of PM cables – 250μm bare fiber PM cable, 900μm loose tube jacket PM cable and 3mm loose tube jacket PM cable.

Length

The standard cable length of PM fiber patch cables is 1 meter. If other lengths are required, the cable is able to be customized to the required lengths as well.

Where to Use PM Patch Cables?

Since PM fibers are typically used to guide linearly polarized light from point to point, PM fibers can be used for many special applications in optical sensors or telecommunications and sensor research. PM fiber patch cables are especially useful for polarization sensitive fiber optical systems where optical light needs to be maintained at a linear state. PM fiber patch cables can be used with other devices like interferometric sensors, integrated optics, fiber amplifiers in high-speed and coherent telecommunications.

Conclusion

As one type of special fiber patch cables, PM patch cables are particularly designed for keeping the polarization of linear optical lights. PM patch cable is definitely a good solution to ensure the high performance of data transmission. FS.COM offers various types of PM patch cables with length customization service. If you are interested in more details, please kindly visit FS.COM or contact us via sales@fs.com.

OM4 vs OM3

40G bandwidths are now being widely adopted within LANs and Data Centres. And 100G will soon be required within your local networks. Here comes the question: what type of fibre network you should choose when planning your 40/100 GbE migration. You have to consider your cabling infrastructure and how it will meet your current and future data requirements. The cables of choice for data center connectivity and what is recommended by the TIA are OM3 and OM4 laser-optimized multimode fiber. In this post, a comparison between OM3 and OM4 fibers will be given.

OM3- or OM4-Preferred Fibers in the Data Center

The IEEE 802.3ba 40/100G Ethernet Standard was ratified in June 2010 and specified parallel optics transmission for multimode fiber. OM3 and OM4 are the only multimode fibers included in the standard. OM3 and OM4 laser-optimized 50/125µm multimode fibers are the choice fiber type for connectivity in the data center. The fibers provide a significant value proposition when compared to single-mode fiber, as multimode fiber utilizes low cost 850 nm transceivers for serial and parallel transmission. Below we look at the differences between OM3 and OM4 multi-mode fibers. The picture shows laser-optimized multimode fiber cables.

laser optimised multi-mode fiber cables

Construction of the Fiber Cable

OM3 is fully compatible with OM4. The connectors are the same, the termination of the connectors is the same, the fibre core size 50/125 is the same, and both fibers are laser optimised multi-mode fiber (LOMMF). The difference is just in the construction of the fibre cable. The difference in the construction means that OM4 cable has better attenuation and can operate at higher bandwidth than OM3.

Attenuation: Attenuation is the reduction in power of the light signal as it is transmitted. It is caused by losses in light through the passive components, such as cables, cable splices, and connectors. The difference in OM3 and OM4 performance is in the loss (dB) in the cable. OM4 causes lower losses.

Dispersion: Dispersion is the spreading of the signal in time due to the differing paths the light can take down the fiber. Modal dispersion, which means that the spreading of the signal in time resulting from the different propagation modes in the fiber. OM3 specifies an effective modal bandwidth (EMB) of 2000 MHz/km, and OM4 of 4700 MHz/km, showing that OM4 can operate at higher bandwidth.

Cost Difference

The cost for OM4 is greater due to the manufacture process and economies of scale that the production of OM3 benefits from due to the volumes currently produced. Costs vary depending on the construction type of the cable (loose tube, tight buffered, etc.). OM4 cable is about twice as expensive as OM3 cable. This means that for lots of products such as standard fibre patch panels, MTP cassette modules, fibre patch cords the cost difference is very small (as the volume of cable is small).

What OM4 Gives You That OM3 Doesn’t?

OM4 effectively provides an additional layer of performance that supports these applications at longer distances, as shown in the following picture. OM4 provides an opportunity to future-proof cabling infrastructure, for it can provide a minimum reach of 125m over multimode fiber within the 40 and 100 GbE standards. Additionally, OM4 provides additional reach at extended bandwidth at an overall cost still less than that of an OS2 singlemode system. In other words, OM4 provides a solution that allows more installations to avoid the significantly higher costs of singlemode systems.

transmission distances

Conclusion

It is important to note that OM4 glass is not necessarily designed to be a replacement for OM3. Despite the relatively long-standing availability of OM4, there are no plans to obsolete OM3 fiber optic cabling. Fiberstore offers you a wide range of cable choices for your 40G Ethernet applications, like OM3 and OM4 fiber optic patch cables. And we also offer other 40G components, such as QSFP+ transceiver, copper cable, active optical cable and QSFP+ cable. You can buy from us with confidence.