A Zero-Bias, Completely Passive 28THz Rectenna for Energy Harvesting from Infrared (Waste Heat)
Waste Heat is available in the mid infrared (IR) range and is a completely untapped area as a renewable energy source. In this work, we show that through the combination of a plasmonic antenna and a high-speed Metal/Insulator/Metal (MIM) diode, a passive rectenna can be formed which can couple and rectify IR to provide useful DC. The plasmonic bowtie antenna has been optimized to provide many orders of field enhancement and then to take advantage of this enhanced localized field. A MIM diode is formed by overlapping the two tips of the bowtie by 200 nm. A 1.5 nm Al2O3 thin film is sandwiched between the two metal arms to realize the MIM diode structure. Two different work function metals (gold and titanium) are used to provide asymmetry, enabling electron tunneling through this MIM diode without any applied bias. A custom optical characterization setup employing a 10.6 µm CO2 laser has been used to demonstrate the IR capture and rectification through the rectenna device. A polarization dependent voltage output which is well above the noise level confirms the successful rectenna operation.