Tunable enhanced transmitted group delays of circular polarization enabled by resonant tunneling in Ag/multi-Weyl semimetal/Ag trilayers

Abstract

The 4 × 4 magneto-optical matrix is theoretically established to investigate the group delays of circular polarization, which are generated by the linearly polarized wave crossing through a sandwich composition that consists of a multi-Weyl semimetal (mWSM) layer and two identical Ag layers. Results denote that the cross-polarized transmission of right hand circularly polarized (RCP) and left hand circularly polarized (LCP) waves experience sharp increases from zero transmission to total transmission at their respective resonant tunneling wavelengths because of the nonzero off-diagonal components of mWSM. Based on the steep change of cross-polarized transmissions, the giant enlarged group delays of several picoseconds can be obtained. Furthermore, the resonant tunneling wavelength of RCP and LCP waves exhibit the dependence on tilt degree of Weyl cones, Fermi energy, Weyl nodes separation and topological charge, which provide feasible strategies to achieve the regulable enhanced group delays. Our findings reveal effective methods to acquire the tunable enlarged group delays of circular polarization with mWSM.

Keywords

• Group delay
• Circular polarization
• Multi-Weyl semimetal
• Cross-polarized transmission