  We study the spin-orbit coupling induced by the splitting between TE and TM
optical modes in a photonic honeycomb lattice. Using a tight-binding approach,
we calculate analytically the band structure. Close to the Dirac point,we
derive an effective Hamiltonian. We find that the local reduced symmetry
($\mathrm{D_{3h}}$) transforms the TE-TM effective magnetic field into an
emergent field with a Dresselhaus symmetry. As a result, particles become
massive, but no gap opens. The emergent field symmetry is revealed by the
optical spin Hall effect.
