Fiber Optic Installer Practice Exam 2025 - Free Fiber Optic Installation Practice Questions and Study Guide

Single-mode fiber optic has a smaller core than multimode fiber optic. This design allows single-mode fibers to transmit light over much longer distances with minimal loss and dispersion. The smaller core size – typically around 8 to 10 micrometers in diameter – enables only a single mode or pathway for light to travel through, thus reducing modal dispersion, which is a common issue in multimode fibers that have larger cores (around 50 to 62.5 micrometers). This characteristic is crucial for long-distance telecommunications, where signal integrity and clarity are paramount.

In contrast, multimode fibers, with their larger core sizes, can carry multiple light modes but are limited in distance due to increased modal dispersion. Therefore, understanding the core size difference is essential in choosing the right type of fiber optic cable for a specific application.