Multimode fiber (MMF) is commonly used in local area networks (LANs) due to its ability to transmit multiple light signals simultaneously. The different grades of multimode fiber are OM1, OM2, OM3, OM4, and OM5, with each grade having specific characteristics that make it suitable for various applications. We are providing a detailed look at each grade, including their current uses, especially for the higher-level grades.
OM1-OM3
OM1’s core size is 62.5 µm, typically uses an LED light source, has a bandwidth of 200MHz*km, and usually the cable has an orange jacket. OM1 is primarily being phased out for new installations due to its limited bandwidth and distance capabilities, 300 meters for 1 GbE and 33 meters for 10 GbE. This grade of fiber is typically found in existing networks (legacy systems) that have yet to be upgraded and in 100 MbE applications.
Similarly to OM1, OM2 utilizes an LED light source and has an orange cable jacket, however, it has a smaller core size of 50 µm and a bandwidth of 500MHz*km. On top of this, OM2 can go double the distance of OM1 for 1 GbE, 600 meters versus OM1’s 300 meters. For 10 GbE, the maximum length is 82 meters, though it is mostly used for its distance at 1 GbE. This grade of fiber is sometimes used in slightly newer installations, in small-to-medium business environments, however it is also being phased out as companies upgrade to fibers with higher -performance.
From OM2 to OM5, the core size remains 50 µm. For OM3 the maximum length for 10 GbE is 300 meters, and although it can support 40 and 100 GbE at 100 meters, 10 GbE is the most used. OM3 has a bandwidth of 2000MHz*km, an aqua cable jacket, and uses VSCEL as an optical source as it is optimized for laser-based equipment. It supports high-speed data transmission and is often chosen for modern data centers.
OM4, OM5, and SWDM
OM4 has the same colored cable jacket as the OM3 and is also completely backwards compatible with OM3 fiber. OM4 was specifically made for VSCEL transmission and allows 10 GbE link distances of up to 550 meters, 250 more meters than the OM3. It can also support 40 and 100 GbE up to 150 meters. With a bandwidth of 4700MHz*km, it’s usually used in environments that need high bandwidth and low latency, such as high-performance computing, data centers, and enterprise networks.
OM5 is the most recent type of multimode fiber. The cable’s jacket is lime green and it’s backwards compatible with OM4. It is also dubbed “wideband multimode fiber” or WBMMF and is made to support at least four wavelength division multiplexing (WDM) channels at a minimum speed of 28Gbps per channel within the 850-953 nm window. The maximum length for 100 GbE is 150 meters and it has a bandwidth of 28000MHz*km.
OM5 is designed to support shortwave wavelength division multiplexing (SWDM) technology, allowing for multiple wavelengths to be transmitted over the same fiber. It is not only used to future-proof for higher speeds, as networks grow towards higher data rates and the demand for bandwidth continues to increase, but also in high-density data centers looking to maximize bandwidth without requiring extra fiber.
SWDM (Shortwave Wavelength Division Multiplexing) is a technology utilized in fiber optics to increase the data capacity of multimode fibers by transmitting multiple signals at different wavelengths (or colors) over the same optical fiber. SWDM is made to work with OM4 and OM5 multimode fibers, allowing for higher data rates over longer distances without needing more fibers.
Typical Dense Wavelength Division Multiplexing (DWDM) is usually used with single-mode fibers, while SWDM is optimized for multimode fibers, particularly OM5, which has better performance for short wavelengths.
The technology is primarily utilized in high-speed network applications such as data centers, enterprise networks, and telecommunications infrastructure, where high bandwidth is required as well as the efficient usage of fiber resources.
Current Uses of Higher-Level Grades (OM3 to OM5)
High-density environments such as data centers use OM3, OM4, and OM5 fibers to support multiple 10/40/100 GbE connections, optimizing performance and reducing latency. Organizations upgrade to OM4 and OM5 to ensure that their networks can handle increasing data traffic, particularly with the popularization of cloud computing and virtualization.
