Understanding the Distinction Between OM4 and OM5, Half 1
Partially one in every of this two-part weblog, we overview the important thing traits of the multi-mode fiber specified by the ISO/IEC 11801 commonplace. Half two will element when OM4 is preferable and when customers can derive profit from utilizing OM5.
Multi-mode fiber is a mainstay of the info middle and campus networking area. Nonetheless, it may be a problem to decide on the precise kind of multi-mode fiber to your cable infrastructure. Of the 5 lessons of multi-mode fiber specified by the ISO/IEC 11801 commonplace, three are in frequent use: OM3, OM4 and probably the most not too long ago outlined model, OM5. OM5 could also be obscure, notably its capabilities and when it supplies benefits over OM4. To make clear the scenario, we overview the usual and how you can quantify the fiber’s efficiency.
The impact of core diameter on fiber modes
Gentle propagates by an optical fiber as a group of spatial modes. Every mode travels a distinct optical path down the fiber, with a various transit time. The broader the core diameter of the fiber, the better the variety of modes it might probably assist. Single-mode fiber has a core diameter 8 to 10 µm, which limits it to supporting just one mode. Multi-mode fiber has a core diameter of 50-62.5 µm, which allows it to assist a number of modes.
We classify multi-mode fiber by its modal bandwidth. The ISO/IEC 11801 commonplace encompasses a number of generations of multi-mode fibers developed with growing bandwidth and, therefore, attain: OM1, OM2, OM3, OM4 and OM5. The usual defines OM1 and OM2 for core diameters of each 50 and 62.5 µm, whereas it calls out OM3, OM4 and OM5 specs for 50-µm core diameters solely.
OM1 and OM2 had been created to be used with LED (Gentle Emitting Diode) sources. The arrival of VCSELs (Vertical Cavity Floor Emitting Lasers) within the late 90s, with their capability to maintain excessive modulation speeds, led to the event of OM3, a brand new class of 50-µm-core multi-mode fiber. OM3 helps 10-Gb/s speeds over hyperlinks of as much as 300 m.
Growing demand for bandwidth prompted producers to work towards a better grade of fiber: LO-MMF (Laser-Optimized Multi-Mode Fiber) with tighter specs. The end result was OM4, which allows 10-Gb/s operation over distances of as much as 400 m. Alternatively, OM4 helps point-to-point 40 Gb/s and 100 Gb/s Ethernet hyperlinks of 4 or 10 pairs of fibers over distances of as much as 150 m.
Most not too long ago, the trade launched OM5. OM5 is a 50/125 µm LO-MMF that’s optimized for efficiency over the operational band of 850 nm to 953 nm. Does this imply OM5 is best to your utility? Not essentially.
Partially two, we are going to overview a key metric used to characterize multi-mode fiber efficiency.
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