Tunable nonreciprocal radiation for near vertical incident light based on graphene and Weyl semimetal

The tunable nonreciprocal radiation for near vertical incident light is investigated. The effect is realized by placing a cascaded one-dimensional graphene and Weyl semimetal (WS) nanowire array on a thick metallic layer. It is observed that perfect absorptivity and emissivity can be realized with different resonant wavelengths, resulting in the achievement of perfect nonreciprocity with an angle of merely 1o. This effect results from the cavity mode resonance (CMR) excited by the WS array, and it is disclosed through analyzing the amplitude distribution of electromagnetic field. In addition, the perfect nonreciprocal radiation could be maintained within a large geometrical dimension range. Furthermore, it is shown that the perfect spectral nonreciprocity could be dynamically tuned by controlling the axial vector of the WS as well as the Fermi level of graphene. The findings will provide new possibility for developing novel energy capture and conversion structure also with advanced thermal systems.