Fiber Optic Attenuator also called optical attenuator, is a passive device used to reduce the power level of an optical signal.
Since too much light may saturate the fiber optic receiver, optical attenuators are often deployed in the system to reduce the light power and achieve the best fiber optic system performance. Generally, multimode systems do not need attenuators as the multimode sources. Instead, for single-mode systems, especially the long-haul DWDM network links, fiber optic attenuators are necessary for balancing the optical power during the transmission.