Spinoptics in a curved spacetime

In this paper we study propagation of the high frequency electromagnetic waves in a curved spacetime. We discuss a so-called spinoptics approach which generalizes a well-known geometric optics approximation and allows one to take into account spin-dependent corrections. A new element proposed in this work is the use of an effective action which allows one to derive spinoptics equations. This method is simpler and more transparent than the earlier proposed methods. It is explicitly covariant and can be applied to an arbitrary spacetime background. We also demonstrate how the initial value problem for the high frequency electromagnetic wave can be solved in the developed spinoptics approximation.