Multimode Cable and Its Type

Posted byVijay Gupta15/05/20200 Comment(s)

Multimode fiber (MMF) is a kind of optical fiber mostly used in communication over short distances, for example, inside a building or for the campus. Multi-mode fiber patch cables are described by the diameters of their core and cladding. There are two different core sizes of multi-mode fiber patch cords: 50 microns and 62.5 microns. Both 62.5 microns and 50 microns patch cable feature the same glass cladding diameter of 125 microns. Thus, a 62.5/125µm multi-mode fiber patch cable has a 62.5µm core and a 125µm diameter cladding; and a 50/125µm multi-mode fiber patch cable has a 50µm core and a 125µm diameter cladding. The larger core of multi-mode fiber patch cords gathers lighter and allows more signals to be transmitted, as shown below. Transmission of many modes of light down a multi-mode fiber patch cable simultaneously causes signals to weaken over time and therefore travel short distance.

 

Difference Between Single mode and Multimode Patch Cables:

Multimode and single mode fiber optic patch cables are different mainly because they have different sizes of cores, which carry light to transmit data. Single mode fiber optic patch cables have a core of 8 to 10 microns. Multimode fiber patch cable allows multiple beams of light passing through, while single mode fiber cable allows a single beam of light passing through. As modal dispersion happens in multimode fiber cable, the transmission distance is relevantly nearer than single mode fiber cables. Therefore, multimode fiber optic patch cable is generally used in relevantly recent regions network connections, while the single mode fiber cable is often used in broader regions.

 

Types of Multimode Fiber Optic Patch Cable:

Multimode fiber optic cables can be divided into OM1, OM2, OM3, and OM4 based on the types of multimode fiber. The letters "OM" stands for optical multimode. OM1 and OM2 belong to traditional multimode fiber patch cable, while OM3 and OM4 belong to the new generation fiber patch cable which provides sufficient bandwidth to support 10 Gigabit Ethernet up to 300 meters. The connector types include LC, FC, SC, ST, MU, E2000, MPO and so on. Different type of connector is available to different equipment and fiber optic cable.

By the materials of optic fiber cable jackets, multimode fiber patch cord can be divided into four different types, PVC, LSZH, plenum, and armored multimode patch cable. PVC is non-flame retardant, while the LSZH is flame retardant and low smoke zero halogen. Plenum is compartment or chamber to which one or more air ducts are connected and forms part of the air distribution system. Because plenum cables are routed through air circulation spaces, which contain very few fire barriers, they need to be coated in flame-retardant, low smoke materials. Armored fiber patch cable use rugged shell with aluminum armor and Kevlar inside the jacket, and it is 10 times stronger than regular fiber patch cable.

 

OM1: These cables come with an orange jacket and have a 62.5 µm core. They support 10 Gigabit Ethernet applications at 33 meters but are usually used for 100 Megabit Ethernet applications. OM1 cables are commonly used in premises applications.

OM1 are for fiber with 200/500MHz*km overfilled launch (OFL) bandwidth at 850/1300nm.

 

OM2: They also come with an orange jacket but have a 50 µm core instead. It is standardized to support 10 Gigabit Ethernet applications at 82 meters but is usually used for 1 Gigabit Ethernet applications. OM2 are Type A1a.1, for fiber with 500/500MHz*km OFL bandwidth at 850/1300nm

Both OM1 and OM2 cables are used in Short-haul networks, Local Area Networks and Private Networks and work with LED transmitters that send hundreds of light modes down the fiber. But they will not support the future’s higher speed demands.

 

OM3: This type of cables has aqua jackets and a 50 µm core. They can run 10 Gigabit Ethernet applications at 300

meters, though it has been improved to work even with 40 and 100 Gigabit Ethernet applications if using an MPO connector, the first one is the most used. They use fewer light modes, which enables higher speeds. And have 1.5 dB connector loss at all speeds.

They are type A1a.2, for laser-optimized 50um fiber having 2GHz*km effective modal bandwidth (EMB, also known as laser bandwidth), designed for 10 Gb/s transmission.

 

OM4: They also have aqua jackets and 50 µm cores but are optimized to support 10 Gigabit Ethernet at 550 meters lengths and 100 Gigabit Ethernet at 150 meters using MPO connectors. They are usually used in High-Speed Networks, Data Centers, Financial Centers and Corporate Campuses.

They are type A1a.3, for laser-optimized 50um fiber having 4.7GHz*km EMB bandwidth designed for 10 Gb/s, 40 Gb/s, and 100 Gb/s transmission.

Both OM3 and OM4 are optimized to work with laser based equipment and they differ from standard multimode cables because they have graded refractive index, which means the refractive index decreases towards the outer cladding, increasing speeds and ensuring data transmission over great distances.

 

OM5: OM5 wideband multimode bend insensitive fiber optimized for multi-wavelengths transmission systems operating in the range of 850-950nm, enabling optimal support of emerging Shortwave Wavelength Division Multiplexing (SWDM) applications that reduce parallel fiber count by at least a factor of four to allow continued use of just two fibers (rather than eight) for transmitting 40 Gb/s and 100 Gb/s and reduced fiber counts for higher speeds.

OM5 meets TIA-492AAAE and draft IEC 60793-2-10 A1a.4 requirements while completely backward compatible with existing OM4 networks and applications.

 

Advantages:

Although single mode fiber patch cable is advantageous in terms of bandwidth and reach for longer distances, multimode fiber easily supports most distances required for enterprise and data center networks at a cost dramatically less than single mode fiber. Besides, multimode fiber optic cable still has many significant advantages.

  • Multi-user Framework Without Loss Interference

Multimode fiber features carrying multiple signals at the same time in the same line. Most importantly, the total power inside the signals carries almost no loss. Therefore, the network user can send more than one packet in the cable at the same time, and all information will be delivered to their destination without any interference and keep unchanged.

  • Support of Multiple Protocols

Multimode fiber can support many data transfer protocol, including Ethernet, Infiniband, and Internet protocols. Therefore, one can use the cable as the backbone of a series of high value applications.

  • Cost-effective

With a larger fiber core and good alignment tolerances, multimode fiber and components are less expensive and are easier to work with other optical components like fiber connector and fiber adapter, and multimode patch cords are less expensive to operate, install and maintain than single mode fiber cables.

 

Applications of Multimode Fiber Optic Patch Cable:

Multi-mode fiber patch cables are used to connect high speed and legacy networks like Gigabit Ethernet, Fast Ethernet, and Ethernet. OM1 and OM2 cables are commonly used in premises applications supporting Ethernet rates of 10Mbps to 1Gbps, which are not suitable though for today's higher-speed networks. OM3 and OM4 are best multimode options of today. For prevailing 10Gbps transmission speeds, OM3 is generally suitable for distance up to 300 meters, and OM4 is suitable for distance up to 550 meters.

 

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