In this letter, we predict that radiative surface phonon polariton (RSPhP) modes, in a multilayer structure consisting of thin-film silicon carbide (SiC) bounded by silicon (Si) and diamond (Di), can be used to achieve negative refraction of mid-infrared light at approximately 11 μm. Dispersion relations, calculated for the Si/SiC/Di structure, show that the RSPhP mode exhibits negative dispersion and couples with incident light. Poynting vector calculations show how the energy flux may be refracted, negatively, in the SiC layer.
Black coatings have important applications in space-borne infrared systems, absolute radiometers, and radiometric
temperature measurements. Recently, researchers have demonstrated close-to-unity absorptance, with diffuse reflection,
by using vertically aligned carbon nanotube (VACNT) arrays. The present study deals with the optical properties of
highly absorbing VACNT arrays, with surface features from diffuse to specular. Three CNT arrays were fabricated using
a thermal chemical vapor deposition (CVD) technique with different growth conditions to produce highly aligned multi-walled
CNT arrays. The bidirectional reflectance distribution functions (BRDFs) were measured with a laser
scatterometer at a wavelength of 635 nm. Sharp specular peaks can be seen from the BRDF plots for the relatively
smooth sample; while for the relatively diffuse samples, the specular peaks are significantly lower. The directional-hemispherical
reflectance (DHR) at wavelengths from 400 to 1000 nm was measured with an integrating sphere and a
monochromator. Based on Kirchhoff's law, the absorptance was obtained from the DHR to be between 99.5% and
99.9% for all samples in the measured spectral region.