In modern enterprise local area networks, campus communication systems, and high-density data center infrastructure, multimode optical fiber acts as the core transmission medium for short-distance high-speed data connectivity. Unlike single-mode fiber designed for long-haul telecom transmission, multimode fiber features a larger core structure that allows multiple light modes to propagate simultaneously inside the fiber core. It delivers cost-effective, stable, and high-bandwidth signal transmission within limited distances, making it the preferred choice for building internal wiring, server interconnection, and enterprise horizontal cabling projects.
As a professional manufacturer and supplier of premium optical fiber products, Weunion develops and supplies standardized multimode fibers covering OM1, OM2, OM3, OM4, and OM5 specifications. All our multimode fiber products comply with ISO/IEC 11801 international industry standards, undergoing strict quality testing to ensure low signal loss, excellent anti-interference performance, and long-term stable operation in complex network environments. This comprehensive guide elaborates on the definition, classification, core differences, and practical application scenarios of various multimode fiber types, helping you select the most suitable multimode fiber for your networking projects.
What Is Multimode Optical Fiber?
Multimode fiber (MMF) is a special optical transmission medium with a relatively large core diameter, supporting dozens or even hundreds of light propagation modes at the same time. Its common core-cladding sizes are 62.5/125µm and 50/125µm, which are much larger than the 9/125µm core of single-mode fiber. Due to the multi-light-path transmission characteristic, multimode fiber inevitably produces modal dispersion, which limits its effective transmission distance, so it is mainly applied to short-range networking scenarios within data centers, office buildings, and campus areas.
In terms of light source matching, early multimode fibers adopt LED light emitters, while new-generation laser-optimized multimode fibers are compatible with high-efficiency VCSEL light sources, greatly improving transmission bandwidth and supporting faster Ethernet rates from Gigabit to 100G. Multimode fiber stands out for easy installation, low construction costs, and high connection tolerance, occupying an indispensable position in short-distance optical networking worldwide.
Main Types of Multimode Fiber (ISO/IEC 11801 Standard)
According to the unified classification regulations of ISO/IEC 11801 international standards, mainstream commercial multimode fiber is divided into five core grades: OM1, OM2, OM3, OM4, and OM5. Each type differs in core size, outer sheath color, supporting light sources, bandwidth capacity, transmission speed, and applicable scenarios.
OM1 Multimode Fiber
OM1 is the earliest mass-produced multimode fiber specification, featuring a 62.5/125µm core-cladding structure and a unified orange outer jacket for easy identification in engineering wiring. It is matched with traditional LED light sources and cannot adapt to laser transmission equipment.
Thanks to its large core aperture, OM1 has strong light-receiving capability and basic bending resistance, but its overall bandwidth is only 200MHz·km, limiting its supported network rates. It can only run stably under Ethernet standards below 10Gbps. At present, OM1 has been gradually phased out of new high-speed network construction and is only used for renovation and expansion of old legacy wiring systems.
Weunion customized OM1 fiber maintains stable optical parameters and durable environmental adaptability for traditional network upgrading projects.
OM2 Multimode Fiber
OM2 is an upgraded version of early multimode fiber, also equipped with an orange outer jacket consistent with OM1 for engineering compatibility. Its core size is optimized to 50/125µm, effectively reducing modal dispersion during light transmission and boosting overall bandwidth to 500MHz·km.
Still adopting LED light source transmission, OM2 performs better than OM1 in both bandwidth and transmission distance, and is widely used in traditional Gigabit Ethernet construction. However, it cannot meet the demands of large-scale 10Gbps high-speed data centers and has been replaced by laser-optimized multimode fibers in new projects. Weunion OM2 fiber provides reliable basic short-distance Gigabit connectivity for small and medium enterprise office networks.
OM3 Multimode Fiber
OM3 marks a revolutionary upgrade for multimode fiber, belonging to laser-optimized multimode fiber with a standard 50/125µm core and a unique aqua-colored outer jacket for quick distinction from legacy orange multimode fibers. It is professionally matched with VCSEL laser light sources, raising the bandwidth up to 2000MHz·km.
OM3 fully supports 10G, 40G, and even partial 100G high-speed Ethernet transmission, becoming the mainstream configuration for modern medium and large data center internal wiring. Compared with OM1 and OM2, it greatly extends the transmission distance of high-rate optical signals and balances performance and cost perfectly. Weunion OM3 laser-optimized multimode fiber is a classic choice for mainstream high-density data center cabling solutions.
OM4 Multimode Fiber
OM4 is an enhanced upgraded model based on OM3 laser optimization, retaining the 50/125µm core structure, with a standard violet outer jacket (individual manufacturers may use aqua color). It further optimizes internal optical design, lifting the effective bandwidth to 4700MHz·km.
OM4 boasts longer high-speed transmission distances and lower signal loss than OM3, effectively supporting stable operation of 40G and 100G Ethernet in large-scale data centers. It is the preferred multimode fiber for high-performance cloud computing data hubs and large enterprise core network building. Weunion high-quality OM4 fiber delivers ultra-stable high-bandwidth transmission for demanding high-speed networking environments.
OM5 Multimode Fiber
OM5 is the latest generation of wideband multimode fiber in the industry, adopting a distinctive lime green outer jacket, with the universal 50/125µm core size same as OM2/OM3/OM4. It is optimized for VCSEL light sources and the SWDM wavelength division multiplexing technology, covering the wide spectral range of 850nm to 953nm and supporting four independent transmission channels simultaneously.
With a bandwidth of 4700MHz·km, OM5 not only inherits all high-performance advantages of OM4 but also realizes higher-density parallel optical signal transmission, perfectly catering to future 200G/400G ultra-high-speed data center construction needs. It is the most future-proof multimode fiber on the current market. Weunion OM5 wideband multimode fiber creates long-term scalable optical infrastructure for next-generation intelligent data centers.
Comprehensive Performance Comparison of OM1 ~ OM5 Multimode Fiber
Basic Physical & Bandwidth Parameters
| Fiber Grade |
Core/Cladding Size |
Jacket Color |
Matching Light Source |
Bandwidth (MHz·km) |
| OM1 |
62.5/125µm |
Orange |
LED |
200 |
| OM2 |
50/125µm |
Orange |
LED |
500 |
| OM3 |
50/125µm |
Aqua |
VCSEL Laser |
2000 |
| OM4 |
50/125µm |
Violet |
VCSEL Laser |
4700 |
| OM5 |
50/125µm |
Lime Green |
VCSEL Laser |
4700 |
Maximum Transmission Distance under Different Ethernet Rates
| Fiber Grade |
100Mbps Fast Ethernet |
1Gbps Gigabit Ethernet |
10Gbps Ethernet |
40Gbps Ethernet |
100Gbps Ethernet |
| OM1 |
2000m |
275m |
33m |
Not Supported |
Not Supported |
| OM2 |
2000m |
550m |
82m |
Not Supported |
Not Supported |
| OM3 |
2000m |
Unlimited |
300m |
100m |
100m |
| OM4 |
2000m |
Unlimited |
550m |
150m |
150m |
| OM5 |
2000m |
Unlimited |
550m |
150m |
150m |
Core Advantages of High-Quality Multimode Fiber from Weunion
- Standard Compliance: All Weunion multimode fibers strictly meet ISO/IEC 11801 and TIA/EIA international specifications, ensuring full compatibility with mainstream optical transceivers, patch panels, and connection components on the market.
- Low Signal Attenuation: Adopting high-purity silica core raw materials, our fibers feature extremely low optical loss, guaranteeing stable signal transmission and reducing network delay and packet loss.
- Durable Outer Protection: Custom anti-UV, flame-retardant, and weather-resistant outer jackets adapt to indoor wiring, outdoor overhead, and complex building pipeline laying scenarios.
- Complete Product Line: Weunion provides full-range OM1 to OM5 multimode fibers with customizable core counts, meeting diverse needs from small office networking to large high-density data center construction.
- Cost-Effective Custom Solutions: Professional R&D and production teams support personalized optical fiber customization, balancing project performance budget and long-term network scalability.
How to Choose the Right Multimode Fiber for Your Project
- For old network renovation, legacy low-speed office networks: Choose economical OM1 or OM2 multimode fiber to match existing LED optical equipment.
- For mainstream 10G enterprise networks and conventional data centers: Select laser-optimized Weunion OM3 fiber for balanced performance and cost.
- For large high-speed 40G/100G cloud data centers: Pick high-bandwidth Weunion OM4 fiber to achieve longer high-rate transmission distances.
- For new-built future-proof ultra-high-density data centers and SWDM parallel transmission systems: Adopt cutting-edge Weunion OM5 wideband multimode fiber to reserve upgrade space for 200G/400G networks.
Conclusion
Multimode optical fiber is an indispensable foundational medium for short-distance high-speed optical communication. From the earliest legacy OM1 and OM2 to laser-optimized OM3, high-performance OM4, and the latest wideband OM5, each generation of multimode fiber evolves to meet growing network bandwidth and speed demands. Differences in core structure, color identification, light source matching, bandwidth capacity, and transmission distance determine their unique applicable scenarios in various networking projects.
Selecting high-quality standardized multimode fiber directly affects the stability, speed, and service life of the entire optical network infrastructure. As a reliable global supplier of optical communication products, Weunion offers a complete portfolio of OM1 to OM5 multimode fiber solutions with strict quality control, excellent technical parameters, and customized service support. Whether you are building a small enterprise LAN, a medium campus network, or a large high-speed intelligent data center, Weunion can provide targeted multimode fiber products to help you build efficient, stable, and future-proof optical networking systems.
If you want to know more detailed parameters, quotations, and application cases of Weunion multimode fibers, please contact our professional sales and technical support team at any time.
