Things You Should Know About Multimode Fiber Optic Cables

In recent years, fiber optic cables have brought a completed revolution for the data transmission system. It has become apparent that fiber-optics are steadily replacing copper wire as a more appropriate ways of communication signal transmission. They span long distances between local phone systems as well as providing the backbone for many network systems. And there are single-mode and multimode fiber optic cable. However, how much are you aware of multimode fiber optic cables? Now, let’s us get together to gain some basic knowledge about multimode fiber optic cables.

Some optical fiber is made of glass, so is multimode fiber. It can provide high bandwidth at high speeds over medium distances. As light waves move through the cable’s core typically 850 or 1300 nm and they are dispersed into numerous paths, or modes. And the diameters of typical multimode fiber core are 50 µm and 62.5 µm. At present there are four kinds of multimode fiber optic cables: OM1, OM2, OM3 and OM4. Each type of them has their features.

Identification

According to the ISO/IEC 11801 standard, multimode fibers are identified by the OM (“optical mode”) designation. Here are their definitions.

  • OM1, for fiber with 200/500 MHz*km overfilled launch (OFL) bandwidth at 850/1300nm
  • OM2, for fiber with 500/500 MHz*km OFL bandwidth at 850/1300nm
  • OM3, for laser-optimized 50um fiber having 2000 MHz*km effective modal bandwidth (EMB, also known as laser bandwidth)
  • OM4, for laser-optimized 50um fiber having 4700 MHz*km EMB bandwidth

Specification

As we can view from the identification, the four fiber optic cables have different bandwidth. Apart from this one, there are numerous differences among OM1, OM2, OM3 and OM4 fiber optic cables.

OM1, usually colored with orange, has a core size of 62.5 µm. LED light source is the optical sources of OM1 multimodes. It is generally used in systems for 10MB/s to 1GB/s Ethernet. And its transmission distance is up to 33 meters in 10 Gigabit Ethernet.

OM2 usually also has an orange jacket. Compared with OM1, its core size is not 62.5 µm but 50 µm. It works well with LED light source as OM1 does. OM2 supports 10 Gigabit Ethernet at lengths up to 82 meters.

OM3 has a suggested jacket color of aqua. Its core size is equal to OM2–50 µm, but the cable is optimized for laser based equipment that uses fewer modes of light. With this optimization, it is able to run 10 Gigabit Ethernet at lengths up to 300 meters. Since its inception, production techniques have improved the overall capabilities of OM3 to enable its use with 40 Gigabit and 100 Gigabit Ethernet up to 100 meters. 10 Gigabit Ethernet is its most common use. Nowadays, in order to meet the industry development needs, OM4 has made great progress.

OM4 also has a suggested jacket color of aqua. It is an upgraded version of OM3. It also uses a 50µm core but it supports 10 Gigabit Ethernet at lengths up to 400 meters, and it can support 100 Gigabit Ethernet at lengths up to 150 meters.

Application

For many years 62.5/125 µm (OM1) and conventional 50/125 µm multimode fiber (OM2) have been widely deployed in premises applications. These fibers offer easily support applications ranging from Ethernet (10 Mbit/s) to Gigabit Ethernet (1 Gbit/s), and because of their relatively large core size, they were suitable for use with LED transmitters.

Today’s deployments usually use laser-optimized 50/125 µm multimode fiber (OM3). Fibers with this designation provide sufficient bandwidth to support 10 Gigabit Ethernet up to 300 meters. Optical fiber manufacturers have greatly refined their manufacturing process since that standard was issued and cables OM4 can be made that support 10 Gigabit Ethernet up to 400 meters. Laser optimized multimode fiber (LOMMF) is designed for use with 850nm VCSELs.

Conclusion

There are various types of multimode fiber optic cables. It is important to make sure you select the fiber with the correct modal bandwidth and model, otherwise it cannot only affect the outcome of your totally integrated automation or integrated Ethernet chips. loss length test, but it will affect what shows up at the bottom of the test report in LinkWare for Network Compliant Standards. Now, do you have a clearly understanding for multimode fiber optic cables?

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