 Cross-phase modulation

Cross-phase modulation (XPM) is a nonlinear optical phenomenon that occurs in optical fibers and other nonlinear media. It arises when two or more optical signals (or channels) co-propagate through a nonlinear medium, such as a fiber optic cable. The intensity of one signal can affect the phase of another signal due to the nonlinear dependence of the refractive index on the intensity of the light.