Final answer:
Single mode fiber optic systems typically use laser light sources, which allow for long-distance, high-bandwidth, and low-loss optical communication with reduced crosstalk.
Step-by-step explanation:
Single mode fiber optic systems typically use laser light sources. Optical fiber communication systems, such as those used for telephone and internet communications, rely on the properties of low loss, high bandwidth, and reduced crosstalk that optical fibers provide.
Optical fibers can carry light for many kilometers without significant loss, which is far superior to electrical (copper) systems. Furthermore, lasers emit light that can support a high number of conversations through a single fiber, exploiting the fiber's high bandwidth, with reduced crosstalk ensuring that optical signals in one fiber do not interfere with those in adjacent fibers.