A multiscale nonreciprocal thermal radiation multilayer structure based on Weyl semimetal with angle and refractive index detection

In this paper, a multiscale nonreciprocal multilayer structure based on the Weyl semimetal is investigated. This multilayer structure enables the realization of nonreciprocal thermal radiation, as well as angle and refractive index (RI) detection at both theta and -theta angles of the forward and backward scenarios. Scenarios are used to describe the electromagnetic waves (EWs) incident from forward or backward with theta or -theta direction. When the EWs incident from the four scenarios, the localized electric field energy caused by the defect mode triggers a sharp emission peak (EP) within the terahertz range. Moreover, the frequency points of EP will shift regularly with changes in physical quantities. Hence, by precisely locating the frequency points of EP, the angle and RI across four scenarios can be detected. The broadest detection range for angle and RI is 30 degrees similar to 70 degrees and 1.4-1.9. Furthermore, the best performance of quality factor, the figure of merit, and the detection limit are 508.9, 1.3 degree(-1,) 4.2 x 10(-2) degrees, and 671.7, 63.6 RIU-1, 7.9 x 10(-4) RIU, respectively. The concepts and conclusions obtained from this article can offer new possibilities for the construction of novel sensing devices, energy harvesting devices, energy conversion devices, nonreciprocal thermal emitters, etc.