Ultranarrow linewidth transverse magneto-optical Kerr Effect in all-dielectric waveguide structures coupled with 2D nanopore arrays for sensing applications

We propose a three-layer all-dielectric waveguide structure incorporating a subwavelength nanopore array in the top layer to enhance the transverse magneto-optical Kerr effect (TMOKE) in reflection mode. The design employs a periodic bismuth-substituted yttrium iron garnet nanoporous grating, which diffracts incident light and enables lateral leakage of guided mode resonance within the dielectric layer. This mechanism leads to a pronounced TMOKE response of up to 0.98, approaching the theoretical maximum of 1. Numerical simulations confirm that the enhancement is robust across a wide range of surrounding refractive indices, indicating strong potential for sensing applications. The proposed structure offers a promising route toward low-loss, highly efficient integrated magneto-optical devices.