Nonreciprocal thermal emitter for transverse electric wave via attenuated total reflection

Abstract

Nonreciprocal radiation is very important in essentially improving energy conversion. There have been many approaches to enhance the nonreciprocal thermal radiation properties for transverse magnetic (TM) wave incidence. However, the nonreciprocal thermal emitters for both polarization states are desired in practice, such as solar cells. In this paper, we design and demonstrate a nonreciprocal thermal emitter for transverse electric (TE) wave. By using attenuated total reflection, the nonreciprocal radiation for TE wave in Weyl semimetal film can be notably enhanced. It shows that the reciprocity between absorption and emission can be strongly broken with the difference of 0.93 at wavelength of 12 μm. Furthermore, the co-polarization and cross-polarization in the reflected wave are calculated to analyze the physical mechanism of strong nonreciprocal radiation. In addition, we discuss the influence of structural parameters, such as the thickness of the air gap, the thickness of Weyl semimetal film, the azimuthal angle and the incident angle, on the nonreciprocity. This work not only provides theoretical guidance for the design of nonreciprocal thermal emitters for TE wave, but also has promising applications in solar cells.