Optical nano-antennas: a new approach for optical imaging and detection

We study theoretically and experimentally the IR emission properties from gold nano-antenna arrays. A new characterization method based on far field measurements only is developed and presented. Excellent agreement in terms of resonance frequencies, optical bandwidth, and emission efficiency is found between the experimental results and a theoretical analysis based on finite element modeling of the arrays. Extremely high overall emission efficiencies, exceeding 95%, are obtained experimentally. The high efficiency and the simple far-field characterization scheme presented here can facilitate the employment of such nano-antennas for numerous applications in imaging, spectroscopy, and solar energy harvesting.