OM2、OM3、OM4、OM5マルチモード光ファイバーの概要

Optical fiber cables fall into two primary categories: single-mode and multimode. Per the ISO/IEC 11801 industry specification, multimode optical fibers are further classified into four standard grades marked with the OM (optical multimode) suffix, namely OM2, OM3 OM4 and OM5.

The classification of multimode fiber is mainly based on the dimensions of its core and cladding, with the most common specifications being 50/125 µm and 50/125 µm. The performance parameters for OM2, OM3 OM4 and OM5 fibers are defined in the ISO 11801 standard, whereas the technical specifications for OM4 fiber are formalized under the TIA/EIA 492AAAD standard. Each OM-grade fiber is therefore assigned a distinct minimum modal bandwidth benchmark to regulate its transmission performance.

When undertaking network upgrade projects, it is essential to evaluate the existing cable infrastructure thoroughly. A well-designed cabling system must be capable of accommodating current data transmission needs while leaving sufficient headroom for future network expansion and rising data traffic demands. Below is a detailed breakdown of the technical specifications and key differences among the four types of OM-series multimode fibers.

OM2: This fiber variant also features an orange outer casing but utilizes a smaller 50 µm core. According to industry standards, OM2 fiber is able to support 10 Gigabit Ethernet transmission at distances up to 82 meters. Despite this capability, it is most commonly deployed for standard 1 Gigabit Ethernet network connections in regular cabling setups.

OM3: Identifiable by its aqua-toned outer jacket, this fiber model adopts a 50 µm core structure. It is engineered to support 10 Gigabit Ethernet connections over a maximum distance of 300 meters. Equipped with MPO connectors, the cable can be upgraded to accommodate 40 Gigabit and 100 Gigabit Ethernet operations, with 10 Gigabit Ethernet still serving as its primary and most widely implemented application. By limiting the number of light transmission modes within the core, OM3 fiber achieves significantly boosted data transfer speeds. Furthermore, it maintains a fixed connector loss value of 1.5 dB across all operational speed grades.

OM4: Boasting the same aqua-colored sheath and 50 µm core specification as OM3 fiber, this upgraded multimode fiber is professionally optimized for longer-distance high-speed transmission. It can deliver stable 10 Gigabit Ethernet transmission over 550 meters, while supporting 100 Gigabit Ethernet connectivity up to 150 meters when paired with MPO connector assemblies. Tailored for premium network scenarios, OM4 fiber is extensively deployed in high-speed network systems, large-scale data centers, financial service hubs and enterprise campus network infrastructures.

Unlike conventional basic multimode fiber types, both OM3 and OM4 cables are optimized for compatibility with laser-based transmission devices. These advanced fiber variants feature a graded refractive index structure, where the refractive index gradually diminishes from the core center toward the outer cladding layer. This specialized structural design effectively enhances overall transmission speeds and enables stable, long-range data delivery, delivering far superior network performance compared to traditional multimode cabling solutions.

OM5: OM5 FIiber cable also known as Wideband Multimode Fiber (WBMMF), is designed to support Short Wavelength Division Multiplexing (SWDM). Unlike previous generations, it uses four distinct wavelengths (850nm to 950nm) to transmit data over a single pair of fibers. This allows for high-speed transmission (40G, 100G, 400G) while significantly reducing the number of cables needed in data centers. It is fully backward compatible with OM3 and OM4 systems but offers greater efficiency for future network upgrades.