Anomalous birefringence through metasurface-based cavities with linear-to-circular polarization conversion

We propose the metasurface-based cavities for splitting a linearly polarized (LP) electromagnetic wave into two symmetric circularly polarized (CP) beams with opposite helicities. More specifically, periodic strip slits and rectangular C-slits etched on substrate integrated waveguide cavities are shown to be capable of perfectly coupling the LP wave into the cavities from the strip slit array, and then releasing them with specific polarization directions according to the orientations of the C-slits. Such metasurface-based cavities with gradient oriented C-slit array would further create the opposite equivalent phase gradients for the right-hand and left-hand CP transmitting waves that are decomposed from the released LP wave with anomalous birefractions and polarization conversion simultaneously.