Symmetry points of Photonic Crystal and R-Soft FDTD

Hello All (and Irfan):

It is mentioned in the R-Soft Full Wave manual that one should avoid launching the field at the symmetry points of the crystal. Why is this?

Thanks in Advance.

V

the coupling between the source and eigenmode may be suppressed due to symmetry. As a result you may not be able to excite certain modes. In this case, these modes will not appear in the band diagram. The eigenmodes have certain symmetries related to the symmetry of the crystal. In short, in order to avoid poor coupling you need to put the source at a low symmetry point.