Which part of the multimode optical fiber has the lowest refractive index?

In multimode optical fiber, the part that has the lowest refractive index is the cladding. The design of an optical fiber involves a core that is surrounded by cladding, which has a lower refractive index than the core. This refractive index difference is crucial for the principle of total internal reflection, which enables light to be transmitted effectively through the core.

The core is the center part of the fiber where light is primarily transmitted, and it has a higher refractive index to ensure that light entering the fiber remains trapped within the core, bouncing off the walls due to total internal reflection. The buffer and coating serve protective functions; the buffer provides mechanical protection and the coating adds a layer of protection against environmental factors. However, neither the buffer nor the coating is involved in the refractive index behavior critical to light transmission within the fiber itself.

Thus, identifying the cladding as the part with the lowest refractive index is vital for understanding how multimode fibers transmit data, emphasizing the importance of material properties in optical engineering.