In this era of high-speed information interconnection, key infrastructure such as data centers and enterprise server rooms are experiencing unprecedented development. In this process, OM1, OM2, OM3, OM4 and OM5 multimode optical fibers play an extremely critical role. Whether you are an experienced expert in the field of IT architecture design or a beginner with a strong interest in optical fiber technology, this article will provide you with an in-depth analysis of all aspects of OM1, OM2, OM3, OM4 and OM5 multimode optical fibers. We will discuss their speed, transmission distance, application scenarios in detail, and conduct technical comparative analysis, while answering some common questions about this topic.
What is Multimode Fiber?
To recap Optical Fiber can be divided into Multimode Fiber (MMF) and Single-Mode optical fiber (SMF).
Multimode Fiber (MMF) has a core diameter, typically 50–100 micrometers, has ability to transfer multiple modes of light through the fiber core, uses lower-cost electronics (LED, VCSEL) operates at the 850 nm and 1300 nm wavelength and is used for short distance interconnections (up to 550m) typically within the same building.
Single-Mode Fiber (SMF) has much smaller core diameter 8–9 micrometers, has ability to transfer only one mode of light thought the core, uses higher cost electronics (DML and EML lasers) operating at the 1310 nm and 1550 nm wavelength which result in lower attenuation and dispersion parameters, which makes SMF suitable for long distance interconnections (up to 100km, or even with use of optical amplifiers and dispersion-compensating devices distances can be in thousands of kilometers).
OM1, OM2, OM3, OM4, OM5 Multimode Fiber Differences
OM1, OM2, OM3, OM4, OM5 Multimode Fiber Specifications
OM1, OM2, OM3, OM4, OM5 Multimode Fiber Distances
ISO/IEC 11801 defines the OM1, OM2, OM3, OM4, and OM5 types of multimode fiber. It also lists the key technical requirements for each type. In the two tables above, we’ve summarized the main differences between OM1, OM2, OM3, OM4, and OM5. These differences include the maximum distance and speed, the standard release date, the modal bandwidth, the size of the fiber core, the color of the fiber jacket, and the typical applications from data rate perspective. Most multimode fiber types used today are OM3/OM4 and OM5, but there are still older network infrastructures, where cables inside buildings were laid a long time ago that use OM1, OM2 multimode fiber.
a、OM1 Fiber
OM1 Multimode fiber type was the first MMF version to be standardized in 1989. It has a larger core diameter (62.5 µm), an orange fiber jacket that is standard in the industry, and an Light-Emitting Diode (LED) light source. It was usually used for 100M Ethernet transmission links, but it is capable of transmitting 1G Ethernet up to 275 meters and 10G Ethernet up to 33 meters.
b、OM2 Fiber
The OM2 fiber type of multimode was standardized in 1998. It still uses LEDs as its light source, but its core when compared to OM1 is smaller – 50 µm in diameter. A fiber jacket that is the same color as OM1 fiber – orange. Most of the time, OM2 fiber was used for 1G Ethernet interconnection in distances up to 550 meters, but it can also be used for 10G Ethernet with distance limitation up to 33 meters.nd data, in an efficient and flexible manner.
c、OM3 Fiber
In 2003, the OM3 fiber type was standardized and is closely linked to the IEEE 802.3 10GbE Ethernet standard. It has a core diameter of 50 µm and a modal bandwidth of 2000 MHz/km. Its main advantage is that it uses laser-optimized multimode fiber (LO-MMF), which is designed to work with vertical-cavity surface-emitting lasers (VCSEL) and was made to support faster networking seeds such as 10G, 40G, and 100G Ethernet. Typically OM3 fiber is used for 10G Ethernet and can make connections up to 300 meters long. However, it can also be used for 25G Ethernet connections up to 70 meters long and 40G/100G Ethernet connections up to 100 meters long.
b、OM4 Fiber
The OM4 fiber type was standardized in 2009, and compared to OM3 fiber , it has a higher modal bandwidth of 4700 MHz/km, while OM3 has a modal bandwidth of 2000 MHz/km. This means that OM4 can send more data than OM3 over the same distance. It leads to the fact that OM4 has better attenuation (OM3 is 3.5 dB/Km and OM4 is 3.0 dB/Km) and dispersion parameters, which allows for longer distances between connections. With OM4 fiber, you can transmit a 10G Ethernet signal up to 400 meters, a 25G Ethernet signal up to 100 meters, and a 40G/100G Ethernet signal 150 meters.
d、OM5 Fiber
OM5 fiber, also called Wide Band Multimode Fibre (WB-MMF), is the newest type of multimode fiber cable standard. It was released in 2016 and is made to support short wavelength division multiplexing (SWDM) transmission. Compared to OM4, the OM5 standard calls for a modal bandwidth of both 4700 Mhz/km at 850 nm and 2470 Mhz/km at 953 nm. What does it mean? It means that OM5 will work much better with multi-wavelength SWDM transceivers (850 nm to 940 nm) like 40 SWDM4, 100G SWDM4, and 400G-BD4.2, but won’t add any extra value when used with standard 1G, 10G, 25G, 40G, and 100G transceivers working at 850 nm range.
Conclusion
Multimode fiber (MMF) is a key part of building short-range connections in data centers or enterprise networks. It is important to know the differences between OM1, OM2, OM3, OM4, and OM5 multimode fiber types and how they are usually used in order to build networks that are both cost-effective and reliable.
FAQ
01、VCSEL vs LED – what are the differences?
VCSELS (vertical-cavity surface-emitting lasers) have a smaller beam angle than LEDs (Light-Emitting Diodes) ; in result VCSEL has more optical power that can be used with the same amount of current or less, resulting in longer-range interconnections. LEDs have their data rate limitation of 622 Mbit/s and as they can’t be turned on and off quickly enough they are unable to support high bandwidth applications. VCSELs can be modulated at speeds over 10 Gbps and are used in high-speed applications.
02、What is effective modal bandwidth (EMB)?
Effective modal bandwidth (EMB), or how much data a certain fiber can send at a certain wavelength, is one of the most important characteristics about multimode fibers. EMB is measured in Megahertz over 1 Kilometer, or MHz/km. For example, OM3 fiber has an EMB of 2000 MHz/km and OM4 fiber has an EMB of 4700 MHz/km, therefore maximum distance for transporting 10G Ethernet over OM3 fiber is 300 meters and over OM4 fiber it is 400 meters.
03、OM3 vs OM4?
OM3 and OM4 are both types of multimode fiber. Both are laser-optimized multimode fibers (LO-MMF) that operate at 850nm. However, OM3 fiber has an EMB of 2000 MHz/km, while OM4 fiber has an EMB of 4700 MHz/km. This means that the maximum distance for 10G Ethernet with OM3 fiber is 300 meters, while with OM4 fiber it is 400 meters.
04、OM4 vs OM5?
OM4 and OM5 are both types of multimode fiber. OM4 is specified at 850nm and has an EMB of 4700 MHz/km. OM5 fiber, also known as Wide Band Multimode Fibre (WB-MMF), has an EMB of 4700 MHz/km at 850 nm and 2470 MHz/km at 953 nm. OM5 is designed to work with multi-wavelength SWDM transceivers, such as 40 SWDM4, 100G SWDM4, and 400G-BD4.2.
05、What is LOMMF – Laser-Optimized Multimode Fiber?
LOMMF is Laser-Optimized Multimode Fibre that is used with VCSELs (Vertical-Cavity Surface Emitting Lasers) to send 10 GbE over long distances in the 850nm wavelength window. Term was first introduced with the OM3 standard.
06、OM1, OM2, OM3, OM4 and OM5 – what does OM stand for?
The letters “OM” stand for optical multi-mode.
07、Are OM1, OM2, OM3, OM4, OM5 backwards compatible?
Yes, you can use a higher OM type to replace a lower OM type. For example, you can use OM3/OM4 or OM5 fiber to replace OM1/OM2 fiber. But because the core sizes are different, you can’t mix OM1 with OM2, OM3, OM4, or OM5.
08、What is multimode fiber max distance?
Multimode fiber max distance will depend on OM type and data rate. For example when using OM3, or OM4 type fiber 1 GbE max distance will be 550 meters, 10 GbE will be 300 meters (OM3), or 400 meters (OM4), 40G/100 GbE 100 meters (OM3), 150 meters (OM4).
