Either fixed or variable components that are manufactured for testing electro-optical components or to incorporate a specific amount of loss into an operational optical network. Attenuators also provide a “safety margin” in planned networks to allow for electronics degradation over time, or physical changes to the optical component portion of the network. Available as fixed with specific amounts of attenuation or a variable optical attenuator (VOA) where the attenuation value can be changed for testing optical components or systems.