  We present a thermal rectification device concept based on far-field
radiative exchange between two selective emitters. Rectification is achieved
due to the fact that one of the selective emitters radiative properties are
independent on temperature whereas the other emitter properties are strongly
temperature dependent. A simple device constituted by two multilayer samples
made of metallic (Au) and semiconductor (Si and HDSi) thin films is proposed.
This device shows a rectification up to 70% with a temperature difference
\Delta T = 200 K, a rectification ratio that has never been achieved so far
with radiation-based rectifiers. Further optimization would allow larger
rectification values. Presented results might be useful for energy conversion
devices, smart radiative coolers / insulators engineering and thermal
modulators development.
