Guide to Multimode Fiber: OM1, OM2, OM3, OM4, OM5

We have previously discussed the distinction between single-mode and multimode fiber, but it's important to note that multimode fiber can be further categorized into five grades: OM1, OM2, OM3, OM4, and OM5.

These different grades of multimode fiber are utilized in high-speed network installations, each offering varying reach and data-rate capabilities. With such a range of options available, it can be challenging to determine the most suitable multimode fiber for your specific network requirements. In this article, we will delve into the specifics of OM1, OM2, OM3, OM4, and OM5 fibers, highlighting the factors that set them apart from each other.

By understanding the unique characteristics of each multimode fiber grade, you can make an informed decision when selecting the appropriate fiber type for your network setup.

What is Multimode Fiber?

Multimode fiber (MMF) is a specific type of optical fiber designed to enable the transmission of multiple light rays or modes simultaneously. Each mode follows a slightly different reflection angle within the core of the fiber.

The primary application of multimode fiber is for relatively shorter distance transmissions, typically within buildings or campuses. This is because the multiple modes are more prone to dispersion over longer distances. For example, the maximum transmission distance for MMF cables is approximately 550 meters at a speed of 10 Gbps. However, at lower data rates, such as 100 Mbps, it can transmit over longer distances, reaching around 2 kilometers.

In contrast, single-mode fiber is another common type of optical fiber primarily used for longer distance transmissions. It allows a single mode of light to propagate, offering higher bandwidth and enabling transmission over much greater distances than multimode fiber.

How Many Types of Multimode Fiber?

Multimode fiber provides a range of cabling options with five distinct types: OM1, OM2, OM3, OM4, and OM5 fibers.

• OM1: OM1 fiber is often distinguished by its orange jacket and features a core size of 62.5 µm. It has a limited capability to support 10 Gigabit Ethernet at shorter distances, up to 33 meters. However, OM1 fiber is commonly employed in 100 Megabit Ethernet applications. It typically utilizes a LED light source for transmission.

• OM2: OM2 fiber shares similarities with OM1 fiber as it also features an orange jacket and employs a LED light source. However, it differentiates itself by having a smaller core size of 50 µm. OM2 fiber is capable of supporting up to 10 Gigabit Ethernet at distances of up to 82 meters. Nevertheless, it is more frequently utilized in 1 Gigabit Ethernet applications.
• OM3: OM3 fiber is distinguishable by its aqua-colored jacket. Similar to OM2, it possesses a core size of 50 µm, but it is specifically optimized for laser-based equipment. OM3 fiber supports 10 Gigabit Ethernet at distances of up to 300 meters. Additionally, it is capable of supporting 40 Gigabit and 100 Gigabit Ethernet at lengths of up to 100 meters. However, it is worth noting that 10 Gigabit Ethernet is the most frequently utilized application for OM3 fiber.

• OM4: OM4 fiber maintains full backward compatibility with OM3 fiber, and it is identifiable by its aqua blue or violet outer sheath. OM4 fiber was specifically developed to optimize VSCEL (Vertical-Cavity Surface-Emitting Laser) transmission. It offers significantly enhanced performance compared to OM3 fiber, enabling 10 Gigabit per second link distances of up to 550 meters, surpassing the 300-meter limitation of OM3 fiber. Moreover, OM4 fiber has the capability to support 40 Gigabit and 100 Gigabit Ethernet at distances of up to 150 meters, utilizing an MPO (Multi-Fiber Push-On) connector. This improved performance and connectivity make OM4 fiber ideal for high-speed data transmission in various applications.

• OM5: OM5 fiber, the newest addition to multimode fibers, offers backward compatibility with OM4 fiber. It features the same core size as OM2, OM3, and OM4 fibers. Recognizable by its water green jacket, OM5 fiber is designed to support a minimum of four WDM channels, each operating at a speed of at least 28 Gbps per channel within the 850-953 nm wavelength range. This capability allows for efficient and high-speed data transmission, meeting the increasing demands of modern communication systems. OM5 fiber provides a versatile and reliable solution for applications requiring multi-channel transmission.

What’s the Difference between Multimode Fibers?

• The physical differences between multimode fiber types primarily manifest in variations in diameter, jacket color, optical source, and bandwidth.

• The practical differences among multimode fibers lie in their transmission capabilities, encompassing varying distance ranges and data rates. Each type of multimode fiber is designed to support specific link distances and data rates, allowing for the selection of an appropriate fiber type based on the desired transmission requirements of a particular application.

Conclusion

Multimode fiber is commonly employed for backbone applications in buildings, thanks to its reliability and high capacity. It remains a cost-effective option for enterprise and data center applications within the 500-600 meter range. However, it is important to note that multimode fiber cannot replace single mode fiber entirely. The choice between single mode and multimode fiber depends on various factors, including the specific application requirements, desired transmission distance, and available budget. Assessing these factors is crucial in determining the most suitable fiber type for a given scenario.