Graded index fiber uses multiple layers of glass to reduce which type of dispersion?

Graded index fiber is specifically designed to reduce modal dispersion, which occurs due to the different propagation speeds of light modes within the fiber. In graded index fiber, the refractive index of the core gradually decreases from the center outwards. This design causes light rays traveling at different angles to bend appropriately as they move through the fiber, allowing the rays that take longer paths to travel faster while the rays taking shorter paths slow down.

As a result, all light rays arrive at the end of the fiber more closely synchronized, thus minimizing the spread of light pulses over distance. This is particularly important in high-speed communication systems where pulse broadening can lead to signal degradation and reduced bandwidth. The engineered structure of graded index fibers effectively tackles the issue of modal dispersion, making it a preferred choice for many telecommunications applications.