Electrically driven ultra-small light sources

Optical antennas are used to enhance the transmittance and receiving of signals at visible light frequencies.  The strongest enhancements can be achieved with “gap antennas”. These antennas can be fabricated by nano-structuring with lithography, Focused Ion Beam (FIB) milling with Gallium or Helium ions or with a gold tip approached to a metal surface. By connecting a gap antenna with electrical leads, which have a sufficient small gap to allow tunneling, these structures can be directly driven by inelastic electron tunneling. In STM the involved energy levels can be easily modified by molecules within the gap and give rise to additional radiative decay channels. By nature the smallest structure than is the single molecule in the tunneling junction.