Enhancement of Transverse Magneto-Optic Kerr effect in subwavelength all-dielectric guided mode gratings with a buffer layer

Abstract

We demonstrate a simple subwavelength all-dielectric photonic device with greatly enhanced transverse magneto-optical Kerr effect (TMOKE) in the transmission mode. The concept utilizes the diffracted waves of the periodic magnetic material bismuth-substituted iron garnet grating to excite the guided mode in the planar waveguide, and adds a buffer layer under the all-dielectric guided mode grating. In the study, it was found that increasing the refractive index of the buffer layer can reduce the coupling between the grating and the waveguide, so that full width at half maximum of the transmission spectra can be narrowed, and the value of TMOKE can be greatly enhanced up to 1.82. It is worth noting that the TMOKE value of the guide mode grating with buffer layer is 3 times that of those without buffer layer, thus opening up different avenues for designing efficient, integrated and low-loss magneto-optical devices. Enhanced TMOKE has great potential for applications such as biosensing/high-resolution sensing, magneto-optical modulation and magnetic measurement.