Polarization insensitive infrared absorbing behaviour of one-dimensional multilayer stack: a fractal approach.

The control and tailoring of infrared absorbance/emittance is a crucial task for all those applications involving thermal radiation management and detection. We theoretically investigated the peculiar absorbing/emitting behaviour of pre-fractal Cantor multilayers, in order to design a polarization-insensitive multilayer stack absorbing over a wide angular lobe in the mid wavelength infrared range (8-10 μm). Using transfer matrix method, we explored the spectral properties arising from both the material and the geometrical dispersion. We considered several combinations of the constituent materials: SiO2 was combined with TiO2 and Si, respectively.