US Patent 7684695 Optical diagnostic indicator

One apparatus embodiment includes a first light source, a second light source, and a receiver having a photodetector. The first light source emits a first signal at a nonvisible wavelength for data transmission. The second light source emits a second signal at a visible wavelength for fault detection when combined with the first signal for transmission over a fiber optic path. The receiver converts the first signal from the nonvisible wavelength to an electrical signal.