Goos-Hänchen shift of normally incident beam on magneto-optical meta-grating

Goos-Hänchen shift of normally incident optical beam to meta-grating consisted of magneto-optical material are studied. The meta-grating is consisted of compound grating of magneto-optical rod on top of a dielectric slab, which induces zone-folding quasi-bound states in the continuum at the $Γ$ point with non-zero group velocity. By applying stationary-phase theory, the Goos-Hänchen shift of normally incident quasi-plane wave are found to be enhanced at the reflection peak. Simulations of normally incident Gaussian beam with finite beam width show that the Goos-Hänchen shift is dependent on the beam width.