OM5 WB MMF Vs 50 µm Laser Optimized OM4 Vs Single-Mode Fiber Cables

Network speeds like 40G and 100G Ethernet have already become the mainstream in data centers, and the industry is still working collaboratively on the next-generation development for higher density and faster speed. Multimode fibers, for example, are treated as the cost-effective solutions for short-reach optical interconnects. OM5 fiber, certificated in 2016, is know as the wide band multimode fiber (WBMMF) designed to carry signals over short wavelength (850nm to 950nm). Many enterprise IT and data center managers nowadays are adopting single-mode fiber system or OM4 cabling in the network infrastructure. Will OM5 MMF be a good alternative for 40G/100G network system? This article will provide the detailed information about OM5 fibers, and make a clear comparison between OM5, OM4 MMF and single-mode fiber cables.

Is OM5 WB MMF Fiber A Good Solution for Data Centers?

No exact answer can be provided here as OM5 MMF is still a new product in 2017.

OM5 MMF fiber has the same geometry as OM4: 50 µm of core size and 125 µm of cladding, which make it fully compatible and intermateable with OM3 and OM4 cabling. OM5 fiber specifies a wider range of wavelengths between 850 nm and 953 nm. The additional specifications of effective modal bandwidth and attenuation at 953 nm is identical to specification of OM4.

It was created to support Shortwave Wavelength Division Multiplexing (SWDM), which is one of the new technologies being developed for transmitting 40 Gb/s, 100 Gb/s, and beyond. With the use of SWDM technology, it is desirable to 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.

The 40/100GbE expected maximum operational distances of OM5 fiber is displayed in the above table. OM5 fiber can support longer distance of 440m for 40G SWDM, and 150m for 100G SWDM system.

How Does OM5 Differ From 50 µm Laser Optimized OM4 Fiber?

Wavelength—OM5 WB MMF is intended for operation using vertical-cavity surface-emitting laser (VCSEL) transceivers across the 846 to 953 nm wavelength range, while OM3 and OM4 50 micron laser optimized multimode fiber, whose bandwidth diminishes rapidly above the 850 nm operating wavelength.

Effective Modal Bandwidth (EMB)—the best system performance is achieved by a combination of low chromatic dispersion and high EMB. OM5 EMB values are specified as following at both 850 and 953 nm.

• EMB>4700 MHz.km at 850 nm
• EMB>2470 MHz.km at 953 nm

However, the OM3/OM4 EMB values are 2000/4700 MHz·km at 850nm. We can see that the OM5 EMB is lower at 953nm compared to 850nm.

More capacity—OM5 is designed and specified to support at least four WDM channels at a minimum speed of 28Gbps per channel through the 850-953 window. Compared to OM4, it is specified only to work at the 850 nm window.

Even though signals illuminating at wavelengths greater than 850 nm will be transmitted by OM3 and OM4, the absence of specification and test data outside the 850 nm window makes it difficult to predict and model the performance of short wavelength-based WDM systems. In conclusion, OM5 is specifically designed to carry at least four channels between 850 nm and 953 nm, and guarantees that capacity increases four times.

• OM5 carries at least 4X more capacity than OM4 over a meter of fiber.
• OM5 carries 5.7X more capacity than OM3 over a meter of fiber.
• OM4 only carries 1.4X more capacity than OM3 over a meter of fiber.

Why Should I Consider OM5 Over Single-mode Fiber?

Cost-effective solution—even thought the costs of single-mode transceivers have declined considerably over the past few years, the delta relative to multimode remains approximately 50%. OM5 MMF fiber allows for more cost-effective migration to transmission speeds up to 400Gbps utilizing lower-cost optics as opposed to single-mode fiber.

Easy management & installation—in 40G/100G network, multimode connectivity together with MTP/MPO systems makes for a more user-friendly solution for data centers as well as building and campus backbones, especially in cable installation, troubleshooting, cleaning, and overall maintenance.

Seamless Migration to 400Gbps—OM5 multimode fiber delivers higher value to network owners for distances up to 500m (for data rates up to 40Gbps), and allows for smooth migration to 400Gbps for distances up to 150m. For distances beyond 500m, single-mode fiber is recommended.

Conclusion

OM5 MMF fiber has a long way to go even though it is being presented as a potential next-generation option for data centers. So far, I don’t see any tempting reasons to recommend OM5 relative to OM4 cables or single-mode fibers for 40G/100G data centers. But FS.COM will keep you upgraded with the latest development of wide band multimode fibers. For more about our 25G/40G/100G optical solutions, please directly visit our website.

DWDM System Helps Expand the 10GbE Network

Dense Wavelength Division Multiplexing (DWDM) network is regarded as the feasible solution to achieve long-distance fiber expansion. DWDM system, with the channel density of 96, has much narrower channel spacing than CWDM system, which allows extremely high utilization of a single fiber strand to pass up to many clients. 10G DWDM SFP+ modules can support a link length of up to 80km. However, the transmission distance of fiber optical network will be affected by factors like date rate, optical signal loss, etc. This article will introduce three instances of how to use DWDM system to extend the transmission distance of 10GbE network.

Basic DWDM Concepts

DWDM uses single-mode fiber to carry multiple light waves of differing frequencies. With the advent of 10G DWDM optics, customers can easily connect up to 80 channels over a single pair of fibers for a maximum distance of 80 km without the need for complicated, bulky and expensive separate DWDM chassis systems. Figure 1 shows the basic working principle of DWDM system.

On the client side, the DWDM node converts the local connection to a channelized frequency or wavelength, which is then multiplexed with other lambdas and transmitted over a single fiber connection. The Transponder interface in a DWDM node performs the conversion from the client side grey wavelength to a channelized lambda or colored wave.

The colored wave is then transported to an optical Mux/Demux port matching the tuned wavelength. Mux/Demux multiplexes multiple colored wavelengths together onto an aggregated signal over a single fiber. The aggregated signals are next passed into a Reconfigurable Optical Add-Drop Multiplexer (ROADM), which is configured to add specific lambdas from the node to the dark fiber line.

The aggregated signal from the ROADM is then passed on to an amplifier to boost the signal on the outbound connection. The node may also employ a pre-amplifier that boosts an incoming aggregated signal as it comes into the node from another location, prior to passing on to a ROADM to drop or pass signals at that node. This is the ring of DWDM system.

Several 10G DWDM Network Solutions

Different specifications of DWDM have different supporting transmission distances. For example, the theoretical transmission distance of 1G DWDM SFP optical modules can reach 100km, while 10G DWDM SFP+ optical module support theoretically up to 80km, so it is essential to choose a kind of optical module that meets the practical needs. However, in the some cases, we may need to extend the transmission distance of the network without replacing optical module, so that some other devices will be required to ensure the transmission quality of the optical signal. Here we will take the DWDM network of 10G DWDM SFP+ optical module as an example to explain the fact that how to extend transmission distance by increasing devices.

• Instance 1: 31km DWDM network

There are two strands of optical signal transmitted between site 1 and site 2, which are operated over C21 and C50 10G DWDM SFP+ transceiver modules separately. The 80km DWDM SFP+ module can support an actual distance of 31 km without increasing other devices, and the data transmission rate can reach to 10Gbps. The light loss of whole solution is 9dB. 40CH DWDM mux/demux is needed for future proofing.

• Instance 2: 57km DWDM network

For longer distance of the DWDM network, OEO is required to transfer all the regular signals into DWDM signals to decrease the risks of fault caused by high power consumption. According to the figure 3, there are two 1G signals and eight 10G signals that are operated on different wavelengths with 80km DWDM modules between site A and site B. The actual linking distance of this layout is 57km with the light loss of 17dB.

• Instance 3: 24km + 47km DWDM network

This solution is the backup plan for instance 2. To overcome the light loss, apart from deploying OEO and DWDM MUX/DEMUX, OADM is also necessary to support the same 6 wavelengths added in Site 4 to ensure Link D and Link E to work independently.

Conclusion

The three instances above are the actual calculated transmission distance of 10G DWDM networks. The solution seems to be quite easy, but you need to pay attention to the optical loss and the budget of dispersion compensation. Besides the DWDM optics, FS.COM offers a full range of WDM devices including EDFA. OEO, DCM, OLP, VOA, etc. For the detailed information about the above layout, please contact us directly.