As data centers scale to ever larger sizes in recent years, the demand for great bandwidth and higher speed is growing too. Recently, OM5 has been approved to be a new type of multimode fiber (MMF) for high speed data center applications. And various discussions about its characteristics and features attract much attention. This article will illustrate three important points that get the most concerns to help you get a clear view on OM5 fiber cable.
OM5, known as wideband multimode fiber (WBMMF) earlier, is a newly standardized fiber cable by TIA and IEC. OM5 is a 50/125µm laser optimized multimode fiber with bandwidth characteristics specified for WDM (Wavelength Division Multiplexing). Compared with OM3 and OM4 which support a single wavelength of 850nm, OM5 is designed to support multiple relatively short wavelengths between 850nm and 953nm that can be aggregated for higher bandwidth applications. Moreover, in February 2017, TIA has approved lime green as identifying color for OM5 fiber optic cable. And the standard multimode fiber connector and adapters for OM3 and OM4 will still work with OM5 fibers. The only difference is that the color of connector and adapter housing or boot needs to be changed for easy identifications of OM5 connections.
Figure 1. OM5 fiber optic cable
Though OM5 shares the same fiber core size with OM3 and OM4, which makes it fully compatible with these types of fibers. That means the OM5 is able to be used in existing multimode fiber applications and supports future speeds when multi-wavelength devices become available.
As mentioned above, OM5 supports applications that using OM3 and OM4 fiber. But there are still differences between them. Here is a simple comparison among OM5, OM4 and OM3.
Jacket color. Generally speaking, the color of standard OM3 and OM4 fiber is aqua. While OM5 fiber is lime green.
Transmitting wavelengths number. OM5 can support at least four short WDM channels at a minimum speed through 850nm-953nm, which makes it different from OM3 and OM4 fiber that only support one wavelength at a time.
Maximum distance and working wavelength. As we all known, the usual working wavelengths of OM3 and OM4 are 850nm and 1310nm. But OM5 supports wavelengths between 850nm and 953nm. In same wavelength windows, the maximum distance of these three MMFs is different.
Figure 2. Maximum distance of OM3, OM4 & OM5 in different requirements
Although the price of single mode fiber (SMF) is reducing recently due to new technologies application, the cost of pluggable optics still limits the implementation of SMF in data centers. Compared to that, OM5 can multiplex four wavelengths spaced in the range of 850nm to 953nm, increasing data capacity by a factor of four as well as reducing fiber cost. Furthermore, MMF has more advantages on installation, troubleshooting, cleaning and overall maintenance, which makes it a better choice in data centers. However, the problem for MMF is distance. And the maximum distance will decrease as the data speed grows. Therefore, multimode fiber has higher value to network owners for distance up to 500m and OM5 allows for migration to 400Gbps at the distance up to 150m. For applications beyond 500m, single mode fiber should be chosen.
At present, OM5 fiber does not support existing optical transceiver. However, in a recent trade show, Finisar and Lumentum present an interoperability of 100G SWDM4 which is a new type of optical transceiver used with OM5. The SWDM4 transceiver uses a complex short wavelength division multiplex (SWDM) technology. Signals at four wavelengths (850nm, 880nm, 910nm and 940nm) are transmitted over one fiber. And only two fibers are required for bidirectional transmission. But this transmission also has limitation—it only suits for 100G to 100G direct connections, which is similar to the application of 100G CWDM4.
Figure 3. SWDM4 over through OM5 MMF
OM5 fiber, as a newly type of multimode fiber optic cable, has gained much attention among various optical vendors and manufacturers. It’s not denied that OM5 fiber will offer completely changes for data centers. But there is still a long way to go.
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