Abstract
Recently, coherent thermal emission characteristics have been demonstrated for both polarizations from a multilayer structure consisting of a one-dimensional (ID) photonic crystal (PC) coated on a silver layer, i.e., PC-on-Ag structure. The key to enabling coherent emission is to excite a surface wave at the PC-Ag interface in the stop band of the PC. A detailed experimental investigation is conducted to demonstrate coherent thermal emission in the near-infrared region from the fabricated PC-on-Ag structure. A Fourier-transform infrared spectrometer, together with a specular reflectance accessory and a polarizer, is used to measure the reflectance at incidence angles of 30° and 45°. In addition, an angle-resolved scatterometer is used to measure the reflectance at the wavelength of 891 nm. Measured reflectance shows very good temporal and spatial coherence. Furthermore, the magnitude of the evanescent waves at the PC-Ag interface is plotted in terms of the wavelength and the incidence angle. It is found that dip locations of the measured reflectance precisely match with the condition when the field intensity is largely enhanced. Copyright © 2007 by ASME.