What effect does increased intensity have on a non-linear fiber regarding the index of refraction?

In a non-linear fiber, the index of refraction is not constant but rather varies with the intensity of the light traveling through the fiber. This phenomenon occurs due to the non-linear optical properties of the material. As the light intensity increases, the interactions between the light and the medium can lead to changes in the refractive index, a characteristic known as the Kerr effect. This effect means that higher light intensities can lead to an increase in the refractive index, causing a variety of non-linear optical effects such as self-focusing, modulation instability, and wavelength shifting.

In summary, the relationship between intensity and the index of refraction in non-linear fibers is dynamic; as intensity changes, so too does the refractive index, allowing for a range of interesting and useful optical phenomena.