Which component of a fiber-optic system is primarily responsible for guiding light?

The core of a fiber-optic system is the critical component responsible for guiding light. It is made of a highly refractive material that allows light to travel through it via the principle of total internal reflection. This means that as light enters the core at a certain angle, it reflects off the walls of the core, allowing it to travel long distances with minimal loss of signal. The core's diameter can vary depending on whether it is single-mode or multi-mode fiber, which affects how light propagates through the system.

While cladding, buffer coating, and sheathing play important roles in the overall structure and protection of the fiber-optic cable, they do not guide light. The cladding surrounds the core and has a lower refractive index, which is crucial for maintaining the total internal reflection that keeps the light traveling within the core. The buffer coating and sheathing provide physical protection and environmental resilience but do not directly interact with the light signal itself. Thus, the core is the key component for light guidance within a fiber-optic system.