Fiber optic cables used in data centers are available in two types—multimode and single-mode fiber optic cable. All fiber optic cables feature a glass core on which light travels. These glass strands are then protected by a plastic coating, the cable construction itself and its jacketing material.
According to CABLExpress, single-mode fiber is fiber optic cable that has a core diameter of 9 µm and offers a higher bandwidth than multimode. This makes them more expensive than their multi-mode counterparts. Single-mode fiber is typically used for longer distance transmissions between buildings.
Additionally, single-mode fiber cables have extremely fast transmission speeds and are immune to distortion, again making them ideal for longer distance runs.
Typical applications include facilities with large campuses, such as colleges and universities, hospital systems, CATV and more.
On the other hand, multi-mode fiber is fiber optic cable that has a core diameter of 50 or 62.5 µm. It is typically used in data centers, where shorter cable lengths are required, and other areas that require high bandwidth and uptime connectivity. On longer runs, they can experience signal distortion and loss of data transmission.
Multi-mode fiber optic cables are commonly used in medical applications, aerospace and LAN networks.
Cable run distance should be your deciding factor when selecting a single- or multi-mode fiber optic cable, with cost being the number two concern. If you’re running more than 2 miles of cable, single-mode fiber should be used.
According to Josh Taylor, Senior Product Manager at CABLExpress, “Single-mode channels can cost an average of 4X more than multi-mode channels, but that includes the electronics that drive the data. While the lasers used in single-mode transceivers are more expensive than those in multi-mode, the cable assemblies themselves are not necessarily more expensive. However, the cost increase to the end-user is in the transceiver that the cable plugs into. Someone installing a single-mode channel will pay more overall, due to the higher cost of the hardware.”
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The advice in this article seems a bit dated to me. FIrst, 62.5 µm multimode cores are obsolete. While there may be a large installed base it is ludicrous to for any new installations to install this first generation OM1 or FDDI grade cabling. At ethernet speeds over 1GB it is virtually useless.
Second, I disagree that MM fiber is less expensive than SM. SM has been around forever and it is a commodity. OM3 MM fiber is vastly more expensive than SM. It is true that the laser based optical transceivers required for SM are much more (4x) expensive than the LED transceivers used by MM. Overall, given the superior capacity and cheaper cost of SM fiber I opt for this in any installation exceeding more than a few hundred meters.