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Metallic layer-by-layer photonic crystals for linearly-polarized thermal emission and thermophotovoltaic device including same

United States Patent

9,400,219
July 26, 2016
View the Complete Patent at the US Patent & Trademark Office
Linearly Polarized Thermal Emitter for More Efficient Thermophotovoltaic Devices
Linearly Polarized Thermal Emitter for More Efficient Thermophotovoltaic Devices
Metallic thermal emitters consisting of two layers of differently structured nickel gratings on a homogeneous nickel layer are fabricated by soft lithography and studied for polarized thermal radiation. A thermal emitter in combination with a sub-wavelength grating shows a high extinction ratio, with a maximum value close to 5, in a wide mid-infrared range from 3.2 to 7.8 .mu.m, as well as high emissivity up to 0.65 at a wavelength of 3.7 .mu.m. All measurements show good agreement with theoretical predictions. Numerical simulations reveal that a high electric field exists within the localized air space surrounded by the gratings and the intensified electric-field is only observed for the polarizations perpendicular to the top sub-wavelength grating. This result suggests how the emissivity of a metal can be selectively enhanced at a certain range of wavelengths for a given polarization.
Lee; Jae-Hwang (Chestnut Hill, MA), Ho; Kai-Ming (Ames, IA), Constant; Kristen P. (Ames, IA)
Iowa State University Research Foundation, Inc. (Ames, IA)
12/ 754,657
20100294325
April 6, 2010
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT This invention was made in part with Government support under Grant Number DE-ACO2-06CH11358 awarded by the Department of Energy. The Government has certain rights in this invention.