The metasurfaces simultaneously exhibit two distinct species of massless Dirac polaritons, namely type-I and type-II. By modifying only the photonic environment via an enclosing cavity, one can manipulate the location of the type-II Dirac points, leading to qualitatively different polariton phases. ...
can be evidently associated with the tilt of thekz-symmetry plane at a Dirac degeneracy point (red line in Fig.2i); and can be, therefore, related to the magnitude of Δns(ts). More specifically, above a critical value (ts,cr), the system transitions to the type-II phase and the ...