Why is single mode fiber preferred for long-distance communication?

Single mode fiber is preferred for long-distance communication primarily because it has lower loss and less signal distortion compared to multimode fiber. The design of single mode fiber allows only one mode of light to propagate through the fiber, which minimizes the dispersion of the light signal as it travels. This characteristic is critical for maintaining signal integrity over long distances since it reduces the likelihood of signal degradation.

When data is sent over long distances, any loss or distortion can result in errors and lower quality of communication. Single mode fibers typically have a smaller core diameter, which helps to limit the number of light modes and hence reduces modal dispersion. This single mode transmission allows for higher bandwidths and longer transmission distances, making it ideal for applications such as telecommunications and data networks requiring high data rates over extensive distances.

In contrast, other options do not provide the same benefits for long-distance communications as single mode fiber does, with costs, core size, and maintenance being secondary to the issues of signal integrity and distance capability.