Selective absorbers and thermal emitters for far-infrared wavelengths

We demonstrate engineered selective absorption and subsequent selective thermal emission from sub-wavelength thickness optical structures at far-infrared (30–40 μm) wavelengths. Control over absorption/emission wavelength is demonstrated, with both polarization-dependent and -independent structures fabricated. Samples are characterized experimentally by Fourier transform infrared reflection and emission spectroscopy, and modeled using three-dimensional rigorous coupled wave analysis. The ability to design and demonstrate strong selective absorption and thermal emission from optical structures in the far-infrared offers a potential route towards low-cost sources for the exploration of Reststrahlen band frequencies.