A Variable Optical Attenuator (VOA) is a controllable device used to reduce the optical power traveling through a fiber or free-space optical path. Bulk attenuators can operate based on several principles, such as filter wheels with neutral density filters, rotated. A VOA (Variable Optical Attenuator) is a fiber optic device that dynamically adjusts the power level of an optical signal by introducing controlled attenuation (loss). In fact, too much light can actually destroy sensitive receiver components or cause bit errors due to signal distortion. This allows output power, for example, to be stabilized at one value even when input power is unstable.