Supermodes in Coupled Bigyrotropic Slab Waveguides

We consider a system of two coupled magneto-optical single-mode slab waveguides separated by an isotropic dielectric spacer. In the transverse magneto-optical configuration, the TE/TM states of polarization can be handled separately. The even/odd supermodes are derived in much the same way as in similar non-magnetic coupled systems; perfect phase-matching ensures a total transfer of energy from one waveguide to the other. The coupling constant can be related to the difference between the propagation constants of the even (slow) and odd (fast) supermodes. Besides, while reversing the magnetization in one of the two waveguides does not affect the phase-matching, it does change the coupling mechanism in a subtle way, thus allowing a magnetic control of the supermodes and of the polarization-dependent coupling efficiency.