Implementation of Unilateral thermal nonreciprocity and front and rear electromagnetic nonreciprocity based on Weyl semimetal

The Weyl semimetal-dielectric multi-layer structure (WDMS) is proposed in this work to achieve nonreciprocal thermal absorption and emission in the mid-infrared wavelength range from both structural orientations. Employing the transfer matrix method (TMM), we effectively calculate emissivity and absorptivity. From both directions of the WDMS, it is observed that non-reciprocity originates at an incident angle of around 30°, with a larger incident angle consistently enhancing this characteristic. Upon increasing the incident angle to 45°, thermal absorption peaks at λ = 3.08 μm from the forward direction, showcasing a stronger non-reciprocity phenomenon as the angle increases. Similarly, from the backward direction, the absorption peak is situated at λ = 3.02 μm. Concurrently, we engage in a thorough discussion of pertinent factors, including the thickness of the unit structure. Furthermore, we delve into the specifics of the Weyl semimetal thickness and the number of periods in the dielectric unit layer. Utilizing simulation software, we observe their collective impacts on non-reciprocity, inducing variations in absorption and emission bands across diverse wavelengths (λ) and angular perspectives (θ). Our research underscores the influence of these factors on non-reciprocity and its impact on absorption and emission bands across varying wavelengths and angles. This work not only contributes to a deeper understanding of nonreciprocal thermal behavior but also offers valuable insights for the innovative design and manufacturing of thermal conversion devices and thermal radiation emitters.