  We study the negative couplings amid local resonances of photonic
metasurfaces. In our analysis, we discover pseudo-spin-orbit coupled bulk modes
leading to lines of circularly polarized radiation eigenstates in
two-dimensional momentum space which were considered to exist only in
three-dimensions. Our theoretical model is exemplified via a guided resonance
dielectric metasurface that possesses Type-II Non-Hermitian diabolical points,
from where the circular polarization lines emanate. The designed metasurface
carries circular polarized radiation eigenstates in both the 0th and the 1st
diffraction orders, allowing spin-selective light deflections. The high quality
factor nature and field enhancement of the designed metasurface could lead to
applications for spin-selective sensing, beam control and nonlinear optics. Our
findings open a gateway for the design of near-field couplings assisted
metasurfaces.
