Tuning thermal emission in metamaterials composed by oriented polar inclusions
We investigated a metamaterial composed by silicon carbide (SiC) subwavelength oriented wires, onto silicon substrate in the mid- to long- infrared range. A simple but versatile method was developed and implemented, combining homogenization techniques with the transfer matrix method for birefringent layered materials to model an effective medium layer where different inclusions content (filling factor) as well as different shape and orientation of inclusions (depolarization factors) are taken into account. The typical spectral features associated to oriented inclusions are thus exploited to design a selective emissivity feature, pertaining sharp resonances at infrared wavelengths. Taming and tuning the strength and the position of the phonon resonance of polar materials allows the design of versatile optical elements and infrared filters, in order to design an effective medium with specifically tuned emissive properties.