The effective lorentzian and teleparallel spacetimes generated by a free electromagnetic field

In this paper we show that a free electromagnetic field living in Minkowski spacetime generates an effective Weitzenböck or an effective Lorentzian spacetime whose properties are determined in details. These results are possible because using the Clifford bundle formalism we found a noticeable result that the energy-momentum densities of a free electromagnetic field are sources of the Hodge duals of exact 2-form fields which satisfy Maxwell like equations.