Independent-regulated double-edge Janus angular absorber for terahertz waves based on photonic edge band gaps and graphene wide-angle absorption

Abstract

In this paper, three categories of Janus angle absorption structures for terahertz (THz) waves are realized by operating the edge hopping property of the photonic band gaps (PBGs) and the wide-angle absorption of graphene heterostructure. The left and right edges of the angle window are determined by the PBGs generated by photonic crystals 1 (PC1) and photonic crystals 2 (PC2), respectively. The appropriate combination of the two can obtain a transmission angle window (TAW), and the edges can be independently manipulated, which makes it possible to construct arbitrary angle filtering structures, making up for the shortage of rigid angle windows in traditional research. Graphene material has absorption potential, and when it is introduced into ternary photonic crystals 3 (PC3), high absorption at large angles will occur. The combination of PC3 and TAW will produce an absorption angle window (AAW) by using the energy cascade transmission features of photonic crystals (PCs). Contributing to the strong absorption properties, the energy transfer on both sides of PC3 is isolated. Consequently, the Janus angle absorption phenomenon will be remarkable by mirroring the PCs structures with different TAWs on both sides of PC3. Through the unique parameter design, the three relationships between the forward AAW and the backward one are investigated, that is inclusion, partial coincidence, and incoherence.