Bandgap formation and selective suppression of Bloch states in birefringent gyrotropic Bragg waveguides

Abstract

Birefringent magnetophotonic crystals are found to exhibit degeneracy breaking for asymmetric contradirectional coupling in planar waveguides. Fundamental to high-order local normal mode coupling leads to partially overlapping gyrotropic bandgaps inside the Brillouin zone and partial suppression of Bloch mode propagation. A large magneto-optically active reorientation in polarization state is found for allowed Bloch modes at bandgap edges.

Elliptical normal modes and stop band reconfiguration in multimode birefringent one-dimensional magnetophotonic crystals

“…Elliptically-polarized normal modes A transfer matrix formulation can be built based on this model to calculate the transmittance of the stack, as described in [17,19,20]. This transfer matrix approach…”

“…Levy and coworkers reported on flat-top response in multiple resonator one-dimensional magnetophotonic crystals [13] and large polarization rotations in waveguide nonreciprocal Bragg systems [14][15][16]. They also studied band gap formation, local normal mode coupling and Bloch states in birefringent magneto-photonic periodic stacks [17][18][19][20]. Degenerate band gap periodic magneto-optic systems were analyzed in [21], while applications of magneto-photonic waveguide Bragg structures to sensors and switches were reported in [22,23].…”

“…Elliptical birefringence arises naturally in magneto-optic waveguides due to the combined effects of magneto-optic gyrotropy and shape anisotropy [14,15,17,19,20]. Stress birefringence, due to lattice mismatch between waveguide film and substrate also contributes to the effect.…”

Gyrotropic band gap optical sensors

“…Previous work by some of us [6][7][8][9] has shown that there is a significant enhancement in polarization rotation near the band edges in magnetophotonic waveguide band gap structures for coupling forward traveling fundamental to backscattered higher-order modes. Preliminary results suggest that this enhancement is due to the combined effect of Faraday rotation and birefringence in waveguide magnetophotonic crystals.…”

“…Magnetophotonic-crystal-enhanced polarization effects provide an interesting alternative platform to explore the RI sensing capability of photonic crystals. [4][5][6][7][8][9] That is because gyrotropic photonic-band gap structures can be made to yield large polarization rotations sensitive to the nature of the cladding in waveguide configurations. [6][7][8][9] In this study we introduce a RI sensor based on the polarization rotation response to changes in cover index in magneto-optic waveguide photonic crystals.…”