What is the key characteristic of single mode fiber optic cable?

The key characteristic of single mode fiber optic cable is that it supports only one mode of light propagation. This characteristic allows single mode fiber to transmit data over longer distances with less signal attenuation compared to multimode fiber. The design of single mode fiber includes a smaller core diameter, typically around 9 micrometers, which is significantly smaller than that of multimode fibers. This smaller core allows light to travel straight down the fiber, reducing modal dispersion—an effect where different light paths cause signals to spread over time. As a result, single mode fibers are ideal for long-distance telecommunications and data transmission applications.

In contrast, the other options do not accurately describe single mode fiber. For instance, multiple modes of light propagation pertain to multimode fiber, which is designed to carry several light paths. Similarly, single mode fiber is actually favored for long distances rather than short applications, which better suit multimode fibers. Additionally, the core diameter of single mode fiber is not larger but smaller than that of multimode fiber, which further distinguishes these two types.