  Using the thin-layer approach, we derive the effective equation for the
electromagnetic wave propagating along a space curve. We find intrinsic
spin-orbit, extrinsic spin-orbit and extrinsic orbital angular momentum and
intrinsic orbital angular momentum couplings induced by torsion, which can lead
to geometric phase, spin and orbital Hall effects. And we show the helicity
inversion induced by curvature that can convert the right-handed circularly
polarized electromagnetic wave into left-handed polarized one, vice verse.
Finally, we demonstrate that the gauge invariance of the effective dynamics is
protected by the geometrically induced gauge potential.

Optics;General Relativity and Quantum Cosmology