Metamaterials approach for infrared radiation manipulation in dispersed nanowires systems

In recent years, much effort has been expended upon managing and tuning the radiative properties of structures and material surfaces in the infrared (IR) wavelength range for several applications, such as thermal radiation control as well as IR sensing. Metamaterials are artificial electromagnetic materials, composed by periodically or randomly arranged, subwavelength elements. Since the typical dimensions of the constitutive elements of a metamaterials are smaller than the interaction wavelengths, they behave as an effective medium and may give rise to peculiar electromagnetic properties, such as negative refraction, superlensing and cloaking, to name some. In the present work we review the use of metamaterials composed by dispersed nanowires systems into a dielectric matrix, for managing and tuning of the infrared emission. The main homogenization techniques effective medium approach are presented and discussed, along with several parameters such as filling factor, inclusions orientations and shape. We finally show some examples with different materials (metallic or polar nanowires) and many configurations in order to get spectral and/or spatial modulation of the resulting infrared emissivity. Taming and tuning the infrared radiation of a metamaterial allows the design of versatile optical elements as basic elements for further developments of infrared filters, thermal diodes and thermal logic gates.