Nonreciprocal Thermal Radiation With Zero-Contrast Gratings for Extreme Small Incident Angle

To achieve the strong nonreciprocal thermal radiation (NTR), a scheme consisting of zero-contrast gratings (ZCGs) and Weyl semimetal (WSM) interlayer sitting on a silver (Ag) substrate is proposed and studied. This structure can be fabricated through the standard mask-based nano-fabrication processes. An almost complete violation of Kirchhoff’s law through the excitation of guided mode resonance (GMR) of ZCGs with an incident angle of only 1° and without an external magnetic field has been demonstrated. The distributions of magnetic field intensity at resonance have been calculated to reveal the underlying physical mechanism. The thorough analysis of the nonreciprocity with respect to structural parameters provides important insights for the design of future corresponding devices, which identifies unique fundamental and technological prospects of WSMs for engineering NTR.