In the context of non-linear optical fibers, what happens to the speed of light as intensity increases?

In non-linear optical fibers, the relationship between the intensity of light and its propagation speed is influenced by the non-linear refractive index change that occurs with increasing light intensity. As the intensity of light in these fibers rises, the refractive index of the medium also changes, leading to a phenomenon known as self-phase modulation.

This effect causes the light to experience a higher refractive index at higher intensities, effectively leading to an increase in the speed of light through the fiber. In non-linear optics, this behavior is tied to the material properties and the dynamics of light, enabling the light to propagate with different phase velocities at variances in intensity. This unique behavior is essential in applications such as soliton generation and optical signal processing.

Therefore, as the intensity of light increases in non-linear optical fibers, the speed of light indeed increases, resulting in the correct answer being that it increases.