Influence of position of magnetooptic layer on differential phase shift of slab waveguide

This paper examines how the position of a magnetooptic layer inside or outside of the core affects the nonreciprocal phase shift of TM modes in a magnetooptic slab waveguide. We find that, with symmetric slabs, the nonreciprocal phase shift is maximized when the magnetic material fills half the slab core. For asymmetrical slabs, the magnetic material should be located on the side of the core facing the cladding layer with the lower refractive index. For best results, the magnetic material should extend from the core boundary to the point inside the core where the longitudinal component of the electric field changes its sign. Effective nonreciprocal phase shifters can also be built by letting one of the cladding regions outside of the slab core be a magnetic material. For best results, the magnetic material should have a higher index than the nonmagnetic cladding layer on the opposite side of the core. Subject to certain qualifying restrictions, the magnetooptic effect increases with increasing penetration depth of the field into the magnetic cladding layer.