Vortical Dichroism of Layered Chiral Media Based on Orbital Angular Momentum

In this communication, the propagation matrix method (PMM) is developed to obtain the vortical dichroism (VD) of layered chiral media based on orbital angular momentum (OAM). The propagation matrices relating four eigenstates and tracing tangential field components through the multilayer are derived by introducing the $y$ component of the wavevector for the vector Bessel vortex electromagnetic (EM) waves. This method allows us to access the VD of the magnetoelectric coupling chiral media via the integration of the angular spectrum expansion method. The effects of chirality, permittivity, topological charge, and thickness on EM characteristics, including the VD for the $s$ and $p$ linearly polarized obliquely incident vortex waves, are investigated. This finding may provide a promising avenue for detecting the chirality and permittivity of a nonhomogeneous chiral structure by wavelength-independent VD.