Investigation of Photon Redistribution in High Temperature Photonic Crystal Structures
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1162-J02-07
Investigation of Photon Redistribution in High Temperature Photonic Crystal Structures W. Zhao1, R. Biswas1,2,*, I. Puscasu3, A. Greenwald3, E. Johnson3 1 Microelectronics Research Center and Dept. of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011. 2 Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames, IA 50011 3 ICX-Photonics, Billerica, MA 01821
ABSTRACT We have simulated the angle-dependent absorption and thermal emittance of two dimensional metallic and metallodielectric photonic crystals (PCs) with rigorous scattering matrix methodswhere Maxwell’s equations are solved in Fourier space. These metallic photonic crystals exhibit strong thermal emittance and absorption peaks in the normal direction. This peak splits into multiple peaks at larger and shorter wavelengths away from the normal direction. The thermal emission at different wavelengths is redistributed into different emission angles. There is partial suppression of photon emission at long wavelengths and enhancement at the shorter wavelength spectral range where the thermal emittance has a maximum. Angle-dependent measurements of the emission in metallo-dielectric photonic crystals are performed. Simulations compare well with these measurements and are consistent with the surface plasmon model. The strong dependence of the absorption with angle is very important for thermo-photovoltaic devices. INTRODUCTION The thermal emission can be substantially modified from the black-body spectrum by utilizing metallic or metallo-dielectric PCs [1-4]. Such PCs exhibit sharp absorption at a wavelength near the lattice period (a). The thermal emission of the PC is observed in a narrow band of wavelengths controlled by this absorption profile. Depending of the temperature of operation and wavelength of the emissive band, these selective emitters utilizing periodic PCs have many potential applications to infrared sensors, infrared sensors, and efficient incandescent sources. Emerging thermophotovoltaic (TPV) systems [5-7] utilize this novel selective wavelength emission. We examine the basis of the energy conversion process in TPV systems, especially the wavelength selective emission. It was proposed that, in a small cone of angles around the normal direction, the enhanced emission of the PCs at the spectral range is due to the funneling of the thermal emission from the forbidden spectral range of the PC (where the absorption/emission is very low) into the allowed spectral range where there the PC has a large absorption [8]. Previous experiments [9,10,11] and analyses were based on thermal emission in near-normal directions which is easy to measure. We perform detailed calculations of the absorption A(λ,θ,φ) and emission M(λ,T,θ,φ) of metallic and metallodielectric PCs at off normal angles. We compare the simulation results with measurements of the metallodielectric PC. We use a recent metallic PC [Fig. 1(a)] developed at Iowa State University [10] and a metallodielectric PC developed at ICXPhotonics
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