Optical amplifiers solve the fiber-loss problem but, at the same time, make the dispersion problem worse because dispersive effects keep accumulating along the entire chain of amplifiers. Indeed, long-haul WDM systems making use of amplifiers are often limited by the dispersive and nonlinear. When all the spectral components are separated from an optical signal, it is termed dispersion. It usually occurs when optical signals travel along optical fiber from transmitter to receiver in an optic–fiber communication link. One of the most widely used technologies for signal amplification is the Erbium-Doped Fiber Amplifier(EDFA).