In fiber optics, what does 'core' refer to?

The term 'core' in fiber optics specifically refers to the central part of the fiber where light travels. This core is typically made from a highly refractive material that allows light to be transmitted through it via total internal reflection. The core's diameter can vary depending on whether it is a single-mode or multi-mode fiber, with single-mode fibers having a smaller core that permits the propagation of light in a single path, while multi-mode fibers have a larger core that supports multiple light paths. This characteristic is essential for efficient data transmission, as the design of the core directly impacts the fiber's performance, including aspects such as bandwidth and distance for signal transmission.

The other options describe parts or concepts related to fiber optics but do not accurately define what the core is. For example, the outer layer is called the cladding, which surrounds the core and has a lower refractive index to help maintain total internal reflection. The protective coating, often made of plastic or other materials, serves to protect the fiber but is not part of the core itself. The entire fiber assembly refers to the complete structure, which includes the core, cladding, and protective layers. Understanding the specific role of the core is crucial for anyone studying fiber optics, as it is fundamental to