Polarization rotation enhancement by high-order waveguide mode coupling in magnetophotonic crystals

Inter-modal coupling in photonic bandgap optical channels in magnetic films is used to leverage the transverse-electric (TE) to transverse-magnetic (TM) mode conversion due to the Faraday Effect. The underlying mechanism is traced to the dependence of the grating coupling-constant on the modal refractive index and the mode profile of the propagating beam, a feature that arises in waveguide propagation and is not present in normal-incidence stack magnetophotonic crystals. Large changes in polarization near the band edges are observed in first and second orders as a result of the photonic bandgap structure. Extreme sensitivity to linear birefringence exists in second order.