Topological edge state coupled mode-induced tetra-band tunable spin-dependent perfect absorption

Abstract When discussing the spin-dependent optical perfect absorption (PA) phenomenon in a micro-nano structure, the designed structure should contain symmetry-breaking compositions that generally require an applied magnetic field. Fortunately, the multi-Weyl semimetal (mWSM) with natural time-reversal symmetry breaking property reveals available schemes to investigate the spin-dependent PA without an external magnetic field. Recently, most present schemes are primarily restricted to single- or dual-band spin-dependent PA in mWSM-based systems. Here we present a heterostructure comprising five one-dimensional photonic crystals (PCs) and four identical mWSM layers to discuss the tetra-band spin-dependent PA. Results show that, due to the topological edge state-coupled mode and the nonzero off-diagonal term of mWSM, the PA of left-hand circularly polarized and right-hand circularly polarized light is attained at four distinct frequencies, respectively. More importantly, the tetra-band spin-dependent PA phenomenon can be regulated effectively via tilt degree of Weyl cones, Fermi energy, topological charge, Weyl nodes separation, mWSM thickness, and periods of the middle three PCs. The research refers an efficient scheme to acquire the tetra-band adjustable spin-dependent PA without an external magnetic field, and might develop potential values in spin-dependent photonic aspects.