Graded index fiber, or also known as gradient index fiber consists of a core that has the characteristics a decreasing refractive index as the radial index increases. Light rays sent through Graded Index fiber do not propagate in a straight line but rather are constantly refracted towards the fiber axis in a parabolic index profile. This is caused by the parts of the core that are closer to the fiber axis having a higher refractive index than the parts near the fiber cladding. The refractive index of the core must be slightly higher than that of the cladding for the light to be guided by the fiber.
Bandwidths for Graded Index fiber can be increased two or three orders larger than that of Step Index fiber. Also, greater propagation speeds can be achieved when the index is smaller in regions that are distant from the core. Those rays propagating through the center travel a shorter distance but because the higher refractive index there, they travel at a lower speed. On the other hand, the smaller refractive index near the cladding causes the rays traveling there to have a higher velocity, but they have a longer distance to travel. By choosing a suitable profile exponent it is possible to compensate for these differences in transit time.
There are two types of GIPOF, one of those being PMMA and the other Perflourinated.
