The enhanced nonreciprocal radiation in a grating structure containing a Weyl semimetal film under conical incidence

The enhanced nonreciprocal radiation in grating structure for light under conical incidence is investigated. The basic structure is composed of a one-dimensional grating on a continuous Weyl semimetal planar and a thick metallic mirror. The results show that near-perfect nonreciprocal radiation can be observed for transverse electric wave, which cannot be achieved for light in traditional incidence. Such effect results from the guided mode resonance (GMR) excited inside the grating, demonstrated by studying the electromagnetic field amplitude distribution. Moreover, the strong nonreciprocity is also stable for the geometric parameters in a wide varying range, lowering the cost of manufacture. Most of important, the proposed scheme could be employed to realize enhanced nonreciprocity for both TM polarization and TE polarization with different resonant wavelengths along with the same resonant wavelength. The concepts proposed here should pave the way to the development of polarization-dependent and polarization-independent as well as dual-polarization nonreciprocal emitters.