What is the Difference Between OM5 Fiber and Existing Multimode Fiber?

In recent years, with the emergence of various new technology applications, data center bandwidth and speed requirements are also growing. OM5 is a new type of multimode fiber used for high-speed data center applications, which has received a lot of attention and discussion in the industry. This article will provide you with detailed answers to common questions about OM5 multimode fiber and help you understand it more clearly.

What Standards does OM5 Fiber Follow?

The Telecommunications Industry Association (TIA) created a working group in 2014 whose responsibilities were primarily to develop a standard for bandwidth multimode fiber supporting shortwave wavelength division multiplexing (SWDM) transmission, the TIA-492AAAE standard, which was completed and published in 2016. Meanwhile, the promulgation of the IEC WB MMF standard was completed in 2017.

What is the Effective Mode Bandwidth of OM5 Fiber? How Does It Compare to OM3/OM4?
The effective mode bandwidth (EMB) of OM5 fiber is 4700 MHz-km at 850 nm and 2470 MHz-km at 983 nm. compared to OM3/OM4 fiber, the effective mode bandwidth of OM5 fiber is 950 nm, as shown in the table below.

What is the Difference Between OM5 Fiber and Other Multimode Fiber?

OM5 is designed to support at least four low-cost wavelengths in the 850 to 950 nm range, enabling emerging short wavelength division multiplexing applications with a reduced number of parallel fibers (by a factor of four), i.e., 40 Gb/s and 100 Gb/s network transmissions using only two fibers, i.e., OM5 enables higher speed network transmissions with reduced fiber usage. In addition, the outer jacket color of OM5 fiber is different from other multimode fiber, lemon green.

What is the Difference Between OM5 and OM4? Does It Transmit Farther than OM4?

In fact, for multimode applications based on IEEE standards (including 40GBase-SR4, 100GBase-SR10), the maximum transmission distance of OM5 is the same as that of OM4. Application tests of the 40G SWDM4 optical transceiver have shown that 40G SWDM4 can reach 400 meters on OM4 fiber, while on OM5 fiber, the transceiver can reach 500 meters. . However, if the data center uses a 100G SWDM4 transceiver that is not compliant with IEEE standards, it can only achieve 150 meters on OM5 fiber, which is only 50 meters farther than OM4.

Is OM5 Fiber Compatible with Existing OM3/OM4 Fiber?

Yes, OM5 supports all legacy applications as OM4; and OM5 has the same geometry as OM3/OM4, i.e. 50μm core and 125μm cladding, so it is backward compatible with these fibers.

Is OM5 Fiber Compatible with Existing Optical Transceivers?

In fact, existing optical transceivers are not compatible with OM5 multimode fiber, and only 40G/100G SWDM4 optical transceivers can be used with OM5 multimode fiber. The OM4 optical transceiver uses complex short-wave WDM technology to transmit signals at four wavelengths (i.e., 850nm, 880nm, 910nm and 940nm) over one fiber, i.e., 2 fibers for bidirectional transmission.

Is the Cost of OM5 Patch Cables Lower than OM4?

For multimode fiber cabling, the cost of OM5 cabling is half the cost of OM4 cabling (mainly because the unit cost of OM5 is higher than OM4).

OM5 Multimode Fiber vs. Singlemode Fiber: How to Choose?

Despite recent price reductions for singlemode fiber due to new technology adoption, deployment of singlemode fiber in data centers is still limited given cabling costs. OM5 supports four lower cost wavelengths than single-mode fiber, which can increase data capacity by up to four times with less fiber usage; in addition, multimode fiber offers more advantages in terms of installation, troubleshooting, cleaning and maintenance, which makes OM5 multimode fiber a good choice for data centers. However, the limited transmission distance is the biggest problem of multimode fiber, which decreases as the data transmission rate increases. Therefore, multimode fiber is a better value for networks up to 500 meters, and for applications beyond 500 meters, singlemode is a more appropriate choice.

Is OM5 Multimode Fiber Really Needed for Higher Speed Transmission?

All IEEE standards in Next Generation 100G/200G/400G Ethernet apply to both singlemode fiber and multimode fiber, but in most cases, Next Generation Ethernet prefers singlemode fiber because multimode fiber is better suited to the installed base of future standard cabling and customers can easily upgrade to higher rates. In addition, none of the IEEE standards for next-generation Ethernet will use SWDM technology.

What’s More

1. What is shortwave wavelength division multiplexing (SWDM)?

Shortwave wavelength division multiplexing (SWDM) means that the wavelength range is extended to support four wavelengths in the range of 850~950nm, drawing on the wavelength division multiplexing technology of single-mode fiber. As shown below, in the shortwave wavelength division multiplexing optical transceiver, the optical signals of four different wavelengths from four VCSELs are multiplexed on a single link to complete data transmission through two parallel fibers (i.e. OM5 multimode fiber), and at the receiving end of the transceiver, the signals are demultiplexed and converted into parallel electrical signals.

2. SWDM technology can support how much transmission rate and transmission distance?

According to the specification standard issued by the SWDM MSA group, the maximum transmission distance ranges from 75 meters to 440 meters based on different transmission rates and fiber types, as detailed in the following table.