Exceptional Points in the Dispersion of Optically Anisotropic Planar Microcavities

When incorporating anisotropic materials, planar microcavities can give rise to exceptional points, i.e. propagation directions along which two otherwise polarization-split photonic modes degenerate in energy and broadening. They are non-Hermitian degeneracies revealing complex-square-root topology and chiral eigenstates. We show computations and experiments on ZnO-based microcavities.