Infrared optical response of geometric diode rectenna solar cells

Optical rectennas, consisting of micron-size antennas coupled to high speed diodes, operate by collecting electromagnetic radiation and converting the high frequency AC field to DC power. We report the demonstration of optical rectennas operating at a wavelength of 10.6 μm. The diode is a graphene device that relies on geometric asymmetry to provide rectification. It is coupled to a metal bowtie antenna 5.1 μm in length. The planar configuration of the diode gives it an extremely low capacitance, making it more suitable for high frequency operation than metal-insulator-metal (MIM) diodes. The theoretical efficiency limit of such devices exceeds the Shockley-Queisser limit, making them suitable for broadband optical operation, and in specific, for thermophotovoltaics.