Fixed single mode and multimode fiber optic attenuators with high-performance doped fiber. 1db to 20db with LC, SC, FC, ST, or MPO connectors available. 2 mm wide key female connector, making it compatible with. Newport's Single-Mode Fixed Fiber Optic Attenuators offer low return loss, high mode stability and a variety of attenuation values: 3, 5, 10, 15 and 20 dB. F-ADAT-13-10-50 Fiber Optic Attenuator, Fixed, 1310 nm. Fiber-optic attenuators are a specific type of optical attenuators which are used in fiber optics, e. for achieving a suitable signal level for a data receiver in a telecom system. Corning's fixed optical attenuators reduce the optical power within a given optical path. A fixed optical attenuator is a passive device that reduces optical signal power by a predetermined, constant amount.