Infrared filters for high-efficiency thermovoltaic devices

Three different infrared filter designs are described for application in high-efficiency thermovoltaic power systems. They are two-dimensional periodic grid arrays with square-loop, circular-loop, or cross aperture (or slot) elements printed on thin dielectric films. These three filters' bandpass performances are demonstrated to transmit the wavelength that can be efficiently converted to electricity, and to reflect other wavelengths back to the heat source, hence conserving energy and increasing the power system's efficiency. The design with cross slot elements exhibits the highest Q bandpass property (or the fastest cutoff for out-of-band wavelength). © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 15: 9–12, 1997.