Which fiber type supports very long distances up to 100 kilometers?

Which fiber type supports very long distances up to 100 kilometers?

• A. Multimode Fiber
• B. Cat6a
• C. Single-Mode Fiber
• D. 802.11a

Answer: (C)

Long-distance optical links rely on minimizing how far the signal spreads as it travels. Single-mode fiber uses a very small core, so light travels in essentially one path. This greatly reduces modal dispersion, meaning pulses stay sharp over long distances. With low attenuation and the right wavelengths (around 1310–1550 nm), signals can traverse tens to hundreds of kilometers, often with amplifiers to extend the reach. Multimode fiber has a larger core and multiple propagation paths, which causes more dispersion and limits practical distance to much shorter ranges, like within a building or campus. Copper like Cat6a is limited to about 100 meters, and wireless 802.11a covers only short-range indoor or urban environments.

Long-distance optical links rely on minimizing how far the signal spreads as it travels. Single-mode fiber uses a very small core, so light travels in essentially one path. This greatly reduces modal dispersion, meaning pulses stay sharp over long distances. With low attenuation and the right wavelengths (around 1310–1550 nm), signals can traverse tens to hundreds of kilometers, often with amplifiers to extend the reach. Multimode fiber has a larger core and multiple propagation paths, which causes more dispersion and limits practical distance to much shorter ranges, like within a building or campus. Copper like Cat6a is limited to about 100 meters, and wireless 802.11a covers only short-range indoor or urban environments.