CHINESE JOURNAL OF PHYSICS, cilt.41, sa.5, ss.475-485, 2003 (SCI-Expanded)
A general relativistic wave equation is written to deal with the electromagnetic waves in a Bianchi type III metric. We obtain the exact form of this equation in a second order form. On the other hand, by using the spinor form of the Maxwell equations, the propagation problem is reduced to the solution of the second order differential equation of a complex combination of the electric and magnetic fields. For these two different approaches we obtain spinors in terms of the field strength tensor.