The Power Of Customer Choice: Optical Fiber Cables for Enterprise Networks
Single-mode Fiber Or Multimode Fiber: Which to Choose?
When planning to build a fiber optic network, the first decision you often encounter is single mode fiber or multimode fiber. Hopefully, I can make that decision easier for you by explaining the differences between the two, and why you should choose one over the other. To make a better choice, we’d better have an overall understanding of single mode fiber and multimode fiber respectively.
Single Mode Fiber
Generally, single mode fibers have a small core size (less than 10 µm) that permits only one mode or ray of light to be transmitted typically 1310 or 1550nm. For this reason, there is little light reflection created when light passes through the single mode fiber core. This will lower fiber attenuation and create the ability for the signal to travel further. Thus single mode fibers usually used in long distance, higher bandwidth applications.
Multimode Fiber
Multimode fibers have larger cores (62.5 µm or 50 µm) that guide many modes simultaneously, which means more data can pass through the multimode fiber core at a given time. This will create more light reflections and higher dispersion and attenuation rate, reducing quality of the signal over long distances. Generally, multimode fibers are used in short distance, data and audio/video applications in LANs.
Each “OM” has a minimum Modal Bandwidth (MBW) requirement. OM1, OM2, and OM3 are determined by the ISO 11801 standard, which is based on the modal bandwidth of the multi-mode fiber. In August of 2009, TIA/EIA approved and released 492AAAD, which defines the performance criteria for OM4. While they developed the original “OM” designations, IEC has not yet released an approved equivalent standard that will eventually be documented as fiber type A1a.3 in IEC 60793-2-10.
According to the above table,
- OM1 cable typically comes with an orange jacket and has a core size of 62.5 micrometers (µm). It can support 10 Gigabit Ethernet at lengths up 33 meters. It is most commonly used for 100 Megabit Ethernet applications
- OM2 also has a suggested jacket color of orange. Its core size is 50µm instead of 62.5µm. It supports 10 Gigabit Ethernet at lengths up to 82 meters but is more commonly used for 1 Gigabit Ethernet applications.
- OM3 has a suggested jacket color of aqua. Like OM2, its core size is 50µm. It supports 10 Gigabit Ethernet at lengths up to 300 meters. Besides OM3 is able to support 40 Gigabit and 100 Gigabit Ethernet up to 100 meters. 10 Gigabit Ethernet is its most common use.
- OM4 also has a suggested jacket color of aqua. It is a further improvement to OM3. It also uses a 50µm core but it supports 10 Gigabit Ethernet at lengths up 550 meters and it supports 100 Gigabit Ethernet at lengths up to 150 meters.
OM1 Vs. OM2 Vs. OM3 Vs. OM4 Fiber
There are several differences between the four kinds of multi-mode fiber, and we can see them clearly from the table below:
- Diameter: The core diameter of OM1 is 62.5 µm, however, the core diameter of the OM2, OM3 and OM4 is 50 µm.
- Jacket Color: OM1 and OM2 MMF are generally defined by an orange jacket. OM3 and OM4 are usually defined with an aqua jacket.
- Optical Source: OM1 and OM2 commonly use LED light source. However, OM3 and OM4 usually use 850 nm VCSELs.
- Bandwidth: At 850 nm the minimal modal bandwidth of OM1 is 200MHz*km, of OM2 is 500MHz*km, of OM3 is 2000MHz*km, of OM4 is 4700MHz*km.
Single-mode Fiber vs. Multimode Fiber: What’s the Difference?
As mentioned above, the inner structure of single mode and multimode fibers are diverse, this naturally leads to the following differences:
The light propagation between single mode fiber and multimode fiber is totally different. Multimode fiber has two types of light propagation—step index and graded index, while single mode fiber has only one step index. And the light propagation reduces less in the single mode fibers transmission than that of multimode fibers.
Single-mode Fiber vs. Multimode Fiber: Which One to Choose?
When selecting single mode fiber or multimode fiber, the most important thing to consider is the distance requirement. Within a data center, it’s typical to use multimode fibers which can get you 300-400 meters. If you have very long runs or are connecting over longer distance, single mode fiber can get you 10km, 40km, 80km, and even farther. You just need to use the appropriate optics for the distance required, and again, the prices go up accordingly.
Video: Singlemode Fiber vs Multimode Fiber
Generally, multimode fiber is more cost-effective choice for data center applications up to 550 meters. Single mode fiber is best used for distances exceeding 550 meters. Besides the transmission distance, the overall cost should also be taken into consideration. Whether single mode fiber or multimode fiber, choosing the one that best suits your network is the smartest choice.
