An electrically modulated plasmonic junction generates surface plasmons from an electrical signal from an electrical source, with the tunnel junction having a contact with a tapered end forming the junction in a gap between the contact and a substrate, with the gap serving to translate electrical signals into surface plasmons that are in turn translated into emitted photons communicated externally through a transmissive oxide, so that the junction can function as an electrically controlled light emitter preferably built as a nano-scale broadband optical emitter whose output wavelength can be electrically tuned over hundreds of nanometers, can be directly modulated at high speeds, and can have improved efficiencies compared to standard silicon optical sources, and the junction can also operate in a reserve mode for light detection.