Fiber optic cables; Fiber optic connectors; Fiber optics; Fibre optic couplings; Laser diodes; Optical semiconductor amplifiers; Photodiodes; Electrical signal attenuators; Electronic and optical communications instruments and components, namely, communication link testers for testing communication links; Electronic and optical communications instruments and components, namely, optical data links; Electronic and optical communications instruments and components, namely, optical receivers; Electronic and optical communications instruments and components, namely, optical transmitters; Electronic and optical communications instruments and components, namely, optical transceivers; Optical fibers; Optical fibres