62.5 micron fiber, known as OM1, is a multimode optical cable with a 62.5 µm core and 125 µm cladding. It uses LED light sources and supports data speeds up to 1 Gbps over 275 m and 10 Gbps up to 33 m. OM1 is common in legacy LAN systems but has been replaced by 50 µm fibers in modern networks.

In the world of networking and data transmission, fiber optic cables are the backbone of high-speed, reliable connections. If you’ve landed here searching for what is 62.5 micron fiber, you’re likely dealing with legacy systems, upgrades, or curious about this classic cable type. Simply put, 62.5 micron fiber optic cable refers to a specific multimode fiber with a core diameter of 62.5 micrometers (µm), designed for short-distance, high-bandwidth applications like local area networks (LANs). Often called 62.5/125 multimode fiber (core/cladding size), it’s an older standard that’s still in use today, especially in enterprise environments.

In the early days of fiber optic networking, 62.5 micron fiber was the standard choice for local area networks (LANs) and enterprise backbones. Known by its ISO classification OM1, this fiber type offered reliable short-distance transmission using LED-based light sources. Although it has since been replaced by higher-performance multimode fibers, OM1 still appears in many legacy installations across offices, campuses, and industrial facilities.

Here’s a quick specs table for 62.5 micron fiber to make it easy to grasp:

Understanding 62.5 Micron Fiber: The Basics

62.5 micron fiber is a type of multimode fiber optic cable (MMF), where light signals travel through a larger core that allows multiple paths (or “modes”) of light to propagate. This contrasts with single-mode fiber (SMF), which uses a tiny 9-micron core for long-haul transmissions.

The “62.5 micron” specifically denotes the core diameter—the glass center where light travels—paired with a 125-micron cladding layer that reflects the light back into the core. Developed in the 1980s and standardized under OM1 (Optical Multimode 1), it was a go-to for early Ethernet networks. Today, it’s synonymous with legacy installations but remains cost-effective for certain setups.

These specs make 62.5/125 multimode fiber ideal for indoor, short-run applications where cost trumps ultra-high speeds.

Common Uses of 62.5 Micron Fiber Optic Cable

62.5 micron fiber shines in scenarios requiring reliable, affordable data transfer over moderate distances. It’s not for long-haul telecom but perfect for:

• Enterprise LANs and Data Centers: Connecting switches, servers, and storage in buildings up to 300 meters apart. Many older offices still run Gigabit Ethernet over this cable.
• Industrial and Warehouse Networks: Dust-resistant variants handle harsh conditions for inventory systems or CCTV.
• Educational and Healthcare Facilities: Low-cost backbone for campus or hospital networks.
• Legacy Upgrades: Extending existing OM1 infrastructure without full rewiring—enhanced 62.5-micron cables now support 300–500 meters for Gigabit Ethernet.

In 2025, with hybrid work and IoT booming, 62.5 micron fiber type is often retrofitted for 10G upgrades in budget-conscious setups, though it’s being phased out for newer OM3/OM4 fibers.

Pros and Cons of 62.5 Micron Fiber

Like any cable, 62.5 micron multimode fiber has trade-offs. Here’s a balanced view:

Pros:

• Affordable: Cheaper than single-mode or laser-optimized multimode (LOMMF) options—ideal for small-to-medium networks.
• Easy to Install: Larger core accepts more light, forgiving for less precise terminations.
• Backward Compatible: Works with legacy equipment like Fast Ethernet (100 Mbps) up to Gigabit speeds.
• Short-Distance Powerhouse: Handles 1 Gbps over 220+ meters without boosters.

Cons:

• Limited Bandwidth: Only 200 MHz·km vs. 500+ MHz·km for 50-micron OM2—struggles with 10G+ speeds beyond short runs.
• Modal Dispersion: Multiple light modes cause signal blurring over distance, capping performance.
• Legacy Status: New installs favor 50-micron fibers for future-proofing; OM1 is “orange jacket” code for outdated.
• Heat and EMI Resistance: Fine indoors, but not as robust as armored single-mode for outdoors.

62.5 Micron vs. 50-Micron Fiber: Which to Choose?

A common search alongside what is 62.5 micron fiber is its rivalry with 50-micron (OM2/OM3/OM4) cables. The key difference? Bandwidth and distance.

• 62.5-Micron (OM1): Broader core (62.5 µm) means more light modes but higher dispersion. Best for <275m Gigabit runs.
• 50-Micron (OM2+): Narrower core (50 µm) reduces modes, boosting bandwidth to 500 MHz·km over 500m at 850 nm—up to 3x farther for Gigabit Ethernet.

Recommendation: Stick with 62.5 micron fiber for maintaining legacy systems (cost savings up to 30%). For new builds, upgrade to 50-micron OM3 for 10G support up to 300m. Always check your transceivers—VCSEL lasers pair better with 50-micron.

Comparison: 62.5 Micron vs 50 Micron Fiber

The smaller core of 50 micron fiber enables better modal control and supports VCSEL laser transmitters, making it ideal for 10G, 40G, and 100G networks.

Is 62.5 Micron Fiber Still Relevant in 2025?

Absolutely—despite the shift to laser-optimized fibers, 62.5 micron fiber optic cable powers millions of networks worldwide, especially in cost-sensitive sectors. With 5G and edge computing, hybrid setups blending OM1 with newer types are common. If you’re searching 62.5 micron fiber type for a project, test your run lengths and consult a fiber certifier for optimal performance.

Ready to spec out your next install? Contact a supplier for OM1 patch cords or consult our fiber buying guide.

62.5 micron fiber—the reliable workhorse of multimode cabling—offers a sweet spot for short-haul, budget-friendly networking. From its 62.5 µm core to Gigabit-ready specs, it’s a staple for legacy and transitional setups. If you’re upgrading, weigh it against 50-micron alternatives for the best ROI.

Got questions on 62.5/125 fiber? Ask us!