Correct option is C
Graded-index optical fiber is designed to reduce modal dispersion, which occurs when different light modes travel at different speeds through the fiber. This is achieved by gradually varying the refractive index of the core.
Refractive Index Profile:
· In a
graded-index fiber, the refractive index of the core decreases gradually from the center to the outer edge. This means that the refractive index is highest at the center and decreases as you move away from the core.
· This gradual change in refractive index helps to focus the light rays and reduce beam spread, allowing for better signal transmission over longer distances.
Comparison with Step-Index Fiber:
· In a
step-index fiber, the refractive index changes abruptly at the core-cladding boundary. This leads to larger beam spread and higher modal dispersion compared to graded-index fiber.
Numerical Aperture:
· The numerical aperture of a graded-index fiber is typically smaller than that of a step-index fiber because the refractive index changes gradually rather than abruptly.
Cladding Layers:
· The cladding in a graded-index fiber does not have multiple layers. Instead, the core itself has a graded refractive index profile.
