Models of Single-mode and Multimode Optical Fibers

Single-mode fibers include OS1 and OS2, while multimode fibers include OM1, OM2, OM3, OM4, and OM5, each optimized for specific distances, bandwidths, and applications.

Single-Mode Optical Fibers

Single-mode fibers have a small core diameter of about 8–10 microns, allowing only a single light mode to propagate. This minimizes modal dispersion, enabling long-distance transmission with high signal integrity, making them ideal for backbone networks and long-haul communications . Types of Single-Mode Fibers:

• OS1: Designed for indoor use, typically in buildings or campus networks. It supports distances up to 2 km and operates at wavelengths of 1310 nm and 1550 nm .
• OS2: Optimized for outdoor and long-haul applications, capable of distances up to 40 km or more. It has lower attenuation and higher bandwidth than OS1, suitable for metropolitan and wide-area networks . Single-mode fibers generally use laser light sources for high-speed data transmission and have higher bandwidth compared to multimode fibers, often exceeding 100,000 GHz .

Multimode Optical Fibers

Multimode fibers have a larger core diameter, typically 50 or 62.5 microns, allowing multiple light modes to propagate simultaneously. This makes them suitable for short-distance, high-capacity applications, such as data centers and LANs . However, modal dispersion limits their effective transmission distance. Types of Multimode Fibers:

• OM1: Core diameter 62.5 µm, supports up to 1 Gbps over short distances (~300 m at 850 nm). It is the least expensive and lowest performing multimode fiber .
• OM2: Core diameter 50 µm, supports 1 Gbps up to 600 m. Slightly better performance than OM1 .
• OM3: Laser-optimized 50 µm fiber, supports 10 Gbps up to 300 m. Common in modern data centers .
• OM4: Enhanced laser-optimized 50 µm fiber, supports 10 Gbps up to 550 m and 40/100 Gbps up to 150 m. Offers higher bandwidth and longer reach than OM3 .
• OM5: Wideband multimode fiber supporting shortwave wavelength division multiplexing (SWDM), enabling multiple wavelengths over a single fiber for higher data rates and future-proofing high-speed networks . Multimode fibers typically use LED or VCSEL light sources, are easier to terminate, and are more cost-effective for short-distance applications compared to single-mode fibers .

Summary

• Single-mode fibers (OS1, OS2): Small core, single light mode, long-distance, high bandwidth, laser sources.
• Multimode fibers (OM1–OM5): Larger core, multiple light modes, short-distance, moderate bandwidth, LED or laser sources, cost-effective for LANs and data centers. Choosing the right fiber type depends on distance, bandwidth requirements, cost, and installation environment, with single-mode preferred for long-haul and multimode for short-range, high-capacity networks .