What is a primary advantage of using single-mode fiber over multi-mode for long-distance links?

What is a primary advantage of using single-mode fiber over multi-mode for long-distance links?

• A. Higher bandwidth over long distances
• B. Cheaper installation
• C. Easier to splice
• D. More rugged

Answer: (A)

The main idea is that single-mode fiber minimizes modal dispersion, which is the spread of light pulses as they travel. In multi-mode fiber, light can take many paths of different lengths inside the core. Those paths cause signals to arrive at the end at slightly different times, broadening pulses and limiting how fast you can reliably transmit data over a given distance. With a single path for the light, pulses stay sharp, so you can push higher data rates over much longer distances. That is why single-mode is favored for long-haul links—the bandwidth over distance product is much larger. The other factors—installation cost, ease of splicing, and ruggedness—do not address this dispersion issue, so they’re not the primary advantage for long-distance use.

The main idea is that single-mode fiber minimizes modal dispersion, which is the spread of light pulses as they travel. In multi-mode fiber, light can take many paths of different lengths inside the core. Those paths cause signals to arrive at the end at slightly different times, broadening pulses and limiting how fast you can reliably transmit data over a given distance. With a single path for the light, pulses stay sharp, so you can push higher data rates over much longer distances. That is why single-mode is favored for long-haul links—the bandwidth over distance product is much larger. The other factors—installation cost, ease of splicing, and ruggedness—do not address this dispersion issue, so they’re not the primary advantage for long-distance use.