Final answer:
A multimode graded-index fiber uses numerous concentric layers of glass to reduce modal dispersion, ensuring total internal reflection and minimal signal loss.
Step-by-step explanation:
The type of fiber that uses numerous concentric layers of glass to reduce modal dispersion is called a multimode graded-index fiber. In fiber optics, the transmission of light down fibers relies on the principle of total internal reflection. The core of the optic fiber is surrounded by a cladding material that has a lower index of refraction than the core itself, which ensures that light reflects back into the core rather than escaping into the surrounding environment. This design helps maintain the light signal's integrity as it travels through the fiber, thus minimizing signal loss and maintaining a high-quality image or transmission at the other end.