Guide to OM1OM5 Multimode Fiber Optics Performance

In the information age, the speed and distance of data transmission are core elements in building efficient communication networks. Multimode fiber (MMF) serves as a common medium for short-distance communication and is widely used in scenarios such as building interiors and campus networks. This article explores the differences between various types of multimode fiber (OM1 to OM5) in terms of core size, bandwidth, data rates, transmission distance, color coding, and light source selection, providing network engineers and system integrators with valuable insights for decision-making.

Multimode fiber features a larger core diameter (typically 50 or 62.5 microns), allowing multiple light modes to propagate simultaneously, thereby increasing data transmission capacity. However, MMF's transmission distance is limited—at 10 Gbit/s speeds, the maximum distance is approximately 550 meters. At lower data rates, such as 100 Mb/s, the distance can extend up to 2 kilometers.

According to the ISO 11801 standard, multimode fiber is categorized into five types: OM1, OM2, OM3, OM4, and OM5. Below, we examine their characteristics in detail.

OM1 fiber typically features an orange outer jacket and a core size of 62.5 microns. While it supports 10 Gigabit Ethernet, its transmission distance is limited to 33 meters, making it more suitable for 100 Megabit Ethernet applications. OM1 commonly uses LED light sources.

OM2 fiber also uses an orange outer jacket and LED light sources but reduces the core size to 50 microns. It supports 10 Gigabit Ethernet with a transmission distance of up to 82 meters but is more commonly deployed for 1 Gigabit Ethernet applications.

OM3 fiber features an aqua blue outer jacket. Like OM2, its core size is 50 microns, but it is optimized for laser equipment. OM3 supports 10 Gigabit Ethernet with a transmission distance of up to 300 meters. It also accommodates 40 Gigabit and 100 Gigabit Ethernet, though distances are restricted to under 100 meters. The most common application for OM3 is 10 Gigabit Ethernet.

OM4 fiber is fully backward-compatible with OM3 and shares the same aqua blue outer jacket. Designed for VCSEL laser transmission, OM4 achieves a 550-meter range at 10 Gbit/s—nearly double OM3's 300-meter limit. Additionally, OM4 can run 40/100GB using MPO connectors, reaching distances of up to 150 meters.

OM5 fiber, also known as Wideband Multimode Fiber (WBMMF), is the latest MMF type and is backward-compatible with OM4. It shares the same 50-micron core size as OM2, OM3, and OM4 but is distinguished by its lime green outer jacket. OM5 is engineered to support at least four WDM channels, each operating at a minimum speed of 28 Gbps within the 850–953 nm wavelength window.

To better understand the distinctions between these fiber types, we compare them across core diameter, data rates, maximum transmission distance, and color coding.

• OM1 and OM2: Larger core diameter (62.5 microns), supporting multiple light modes but limiting higher data rates over longer distances.
• OM3, OM4, and OM5: Smaller core diameter (50 microns), enabling higher data rates and extended transmission distances.

• OM1 and OM2: Typically support speeds up to 1 Gbit/s, ideal for slower, short-distance connections.
• OM3: Supports speeds up to 10 Gbit/s, suitable for faster network demands.
• OM4: Supports 10 Gbit/s, 40 Gbit/s, and 100 Gbit/s, optimized for high-speed VCSEL-based applications.
• OM5: Supports 10 Gbit/s, 25 Gbit/s, and 100 Gbit/s, designed for emerging high-bandwidth applications.

• OM1: ~300 meters at 1 Gbit/s.
• OM2: ~550 meters at 1 Gbit/s.
• OM3: 300 meters at 10 Gbit/s.
• OM4: Up to 400 meters across multiple data rates (10/40/100 Gbit/s).
• OM5: 150 meters at 100 Gbit/s.

OM1 and OM2 fibers are typically orange, while OM3 and OM4 use aqua blue. OM5 is distinguished by its lime green jacket.

• Core Diameter: Single-mode fiber (SMF) has a smaller core (8.3–10 microns), allowing only one light mode, while MMF's larger core (50–100 microns) supports multiple modes.
• Light Source: MMF uses LEDs or lasers, whereas SMF relies on laser diodes.
• Distance: SMF supports longer distances, while MMF is cost-effective for short-range applications (≤550 meters).
• Bandwidth: SMF offers up to 100,000 GHz, far exceeding MMF.

Common MMF connectors include ST, SC, FC, and LC. Below is a comparison of their key attributes:

Despite single-mode fiber's superior bandwidth and distance capabilities, MMF remains a cost-effective solution for most enterprise and data center needs, offering several key benefits:

• Multi-User Framework: Supports simultaneous transmission of multiple signals without interference.
• Protocol Support: Compatible with Ethernet, Infiniband, and Internet protocols.
• Cost Efficiency: Lower installation and maintenance costs compared to SMF.

• Bandwidth and Distance: OM5 offers higher bandwidth than OM3/OM4, making it ideal for high-throughput applications.
• Channel Loss: OM5 reduces attenuation to 3.0 dB/km (from 3.5 dB/km in OM3/OM4).
• Cost: OM5 cabling costs ~50% more than OM4.

OM5 is backward-compatible with OM3 and OM4, enabling seamless network upgrades. However, for distances exceeding 500 meters, single-mode fiber remains the preferred choice.