Fourth order method for Maxwell equations on a staggered mesh

We consider fourth order accurate compact schemes for numerical solutions to the Maxwell equations. We use the same mesh stencil as used in the standard Yee scheme. In particular extra information over a wider stencil is not required. Hence, it is relatively easy to modify an existing code based on the Yee algorithm to make it fourth order accurate. Also, a staggered mesh makes the boundary treatment easier. Finally, a staggered grid system gives a lower error than a non-staggered system.