oh, the picture gets into a mass. hope someboday can understand it.
III and II are the regions just above and below the waveguide core, which is noted as I.
IV and V are the regions on the right and left of the core I.
i am now trying to figure out the electro-field around a rectangle waveguide. the refractive index of the waveguide is n1, which is larger than that of the cladding, namely n2, outside. we may regard the waveguide embeded in the cladding material.
as following shown, the waveguide...