Light-matter interaction involving photons with large period τ of ~ 3 fs (10-15 s) and above, i.e. infrared (IR) to microand radio-waves, displays interesting properties so far mostly unexplored. These photons indeed can produce voltages after activating charges or currents. For example, in the literature it is demonstrated that animals and plants neural system (which is similar to a system consisting of capacitors in series) can be stimulated by IR photons. Additionally, radio waves can activate currents in antennas. However, a systematic investigation of the voltages and currents produced, of the charge density changes, and of the number of photons involved is missing. Here we initiate the investigation of the voltages produced by a capacitor-type device. We shine broadband IR light in the middle IR region (MIR) at a power of 25 mW onto capacitors with capacitance C from 30 to 300 pF. We observe that the voltage produced increases with decreasing C while developing negligible temperature changes. Further increases can be obtained by increasing τ and, modestly, by deviating from normal incidence the angle of incidence θ between the IR light and the illuminated plate of the capacitor. Specifically, here we compare τ in the MIR and far IR (FIR) regions, and θ from 0° (normal incidence) to 45°. The effects of the power of the light will be explored in the near future. These results suggest that it is possible to harvest and transform IR, micro- and radio-waves into usable and sustainable electricity.
Thomas C. St. John, Zachary J. Marinelli, Justin M. Kaczmar, Robert P. Given, Kyle S. Wenger, Brian C. Utter, and Giovanna Scarel, "Conversion of infrared light into usable energy," Proc. SPIE 9927, Nanoengineering: Fabrication, Properties, Optics, and Devices XIII, 99270C (Presented at SPIE Nanoscience + Engineering: August 30, 2016; Published: 15 September 2016); https://doi.org/10.1117/12.2236971.
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