Optical cables are classified primarily by the type of optical fiber they contain, including single-mode and multimode fibers, core size, wavelength, and compliance with international standards.

Core Classification: Single-Mode vs Multimode

Single-mode fibers (SMF) have a small core diameter, typically around 9 microns, allowing only one light path to propagate. This minimizes signal dispersion and supports long-distance, high-bandwidth applications such as telecommunications and cable TV networks (OS1/OS2 standards) . Multimode fibers (MMF) have larger cores, usually 50–62.5 microns, allowing multiple light paths. They are suitable for shorter distances due to higher modal dispersion. Multimode fibers are further classified into OM1, OM2, OM3, OM4, and OM5, with increasing bandwidth and distance capabilities. OM5 supports advanced technologies like short wavelength division multiplexing for higher data rates .

Core/Cladding Size and Wavelength

Optical cables are also classified by core and cladding diameters, which affect transmission mode and compatibility with light sources. Single-mode fibers typically operate at 1310 nm or 1550 nm wavelengths, while multimode fibers use 850 nm or 1300 nm . Wavelength band classification is used to optimize fiber for specific applications, such as CWDM systems or long-haul interconnections, with zero-dispersion points around 1310 nm for G.652 fibers .

Standards and Compliance

Fiber optic cables adhere to international standards such as IEC, ITU-T, and TIA/EIA, which define performance, attenuation, and mechanical properties. For example, G.652D and G.657A2 are common single-mode fiber standards, while OM4 and OM5 define multimode fiber performance .

Applications and Construction

Cables are designed for specific environments:

• Distribution cables: 12–24 fibers for horizontal runs in buildings.
• Patch cords: Short, pre-terminated cables for device connections.
• Aerial, direct burial, duct, and submarine cables: Designed for outdoor, underground, or underwater use with protective jackets and armor . The classification ensures that the optical cable meets the required distance, bandwidth, and environmental conditions for its intended application, making fiber selection critical for network performance and reliability .