  Recently microcavities with anisotropic materials are shown to be able to
create novel bands with non-zero local Berry curvature. The anisotropic
refractive index of the cavity layer is believed to be critical in opening an
energy gap at the tilted Dirac points. In this work, we show that an
anticrossing between a cavity mode and a Bragg mode can also form within an
empty microcavity without any birefringent materials. Flat bands are observed
within the energy gap due to the particular refractive index distribution of
the sample. The intrinsic TE-TM splitting and XY splitting induce the squeezing
of the cavity modes in momentum space, so that the flat bands are
spin-dependently tilted. Our results pave the way to investigate the spin orbit
coupling of photons in a simple microcavity without anisotropic cavity layers.

Optics;Mesoscale and Nanoscale Physics