Optical attenuator is a passive device used to reduce the power level of an optical signal. It is generally used in single-mode long-haul applications to prevent optical overload at the receiver.

Optical attenuator is widely used in CWDM&DWDM, CATV systems, data center networks, test equipment and other high power applications. As optical passive devices, Fiber optic attenuators are primarily used in fiber optic systems to debug optical power performance by providing desired fiber signal attenuation to ensure the optical power to be stable and at a desired level in the link without any changes on its original transmission wave.