On-chip photonic crystals on magnetic garnet films

By trapping photons in fabricated phase-shift defects magnetic photonic crystals can enhance the Faraday rotation in magneto-optic films. The integration of these structures into on-chip photonic circuits, while advantageous from the point of view of component connectivity in multi-functional systems, faces several challenges. Differences in effective refractive indices between transverse electric (TE) and transverse magnetic (TM) modes engender phase disparities, thus hindering the Faraday response of the material. Moreover, photonic waveguide structures in magnetic films may support more than one mode depending on the waveguide thickness and refractive index. The effects of birefringence and multimodality on the performance of waveguide magnetic photonic crystals in magnetic garnets are discussed in paper. Particular attention is paid to analyzing the effect of Faraday rotation enhancement in magnetophotonic crystals in the presence of waveguide birefringence and modal multiplicity. Multiple stopbands and significant polarization rotation are observed in multimode Bi-substituted iron garnet film waveguides with single-defect photonic crystal structures. A spectrally flat response is predicted for the polarization rotation in first order mode for birefringent waveguides. The photonic crystals for this study are patterned on ridge waveguide films by focused ion beam (FIB) milling