Nonlocal optical effects on the Goos-Hänchen shift at an interface of a composite material of metallic nanoparticles

Enhancing the nonreciprocal Goos-Hänchen shift by the Fano resonance of coupled gyromagnetic chains at normal incidence

We report a resonance-enhanced nonreciprocal Goos-Hänchen (GH) shift for the wave reflected from the coupled gyromagnetic chains. We demonstrate that the Fano resonance enhances the GH shift with high reflectivity at normal incidence, and the resonance results from the interference between the leaky guided modes of the coupled chains. Furthermore, we show that the GH shift can be controlled by the number of stacked chains. The Fano resonance-enhanced GH shift offers a new efficiently way to enhance and control the GH shift for reflected wave beam. Such coupled gyromagnetic chains provide an extremely compact way for the devices such as unidirectional couplers and other integration photonic components, paving the way for the applications of nonreciprocal GH shift.

Nonreciprocal Goos-Hänchen shift by topological edge states of a magnetic photonic crystal

We demonstrate that a topological edge state can enhance the Goos-Hänchen (GH) shift on the interface of a magnetic photonic crystal (MPC) fabricated by ferrite rings in a square lattice. The GH shift is nonreciprocal because of the time reversal symmetry breaking, and the shift is negative, which is associated with the incident angles and direction of bias DC magnetic field. In particular, the nonreciprocal GH shift presents at normal incidence, and is further verified by experiments. The nonreciprocal negative GH shifts provide a new way to control the flow of light, which could be applied to sensing and even the slow light waveguide to trap the light.

Magnetic control of Goos-Hänchen shifts in a yttrium-iron-garnet film

We investigate the Goos-Hänchen (GH) shifts reflected and transmitted by a yttrium-iron-garnet (YIG) film for both normal and oblique incidence. It is found that the nonreciprocity effect of the MO material does not only result in a nonvanishing reflected shift at normal incidence, but also leads to a slab-thickness-independent term which breaks the symmetry between the reflected and transmitted shifts at oblique incidence. The asymptotic behaviors of the normal-incidence reflected shift are obtained in the vicinity of two characteristic frequencies corresponding to a minimum reflectivity and a total reflection, respectively. Moreover, the coexistence of two types of negative-reflected-shift (NRS) at oblique incidence is discussed. We show that the reversal of the shifts from positive to negative values can be realized by tuning the magnitude of applied magnetic field, the frequency of incident wave and the slab thickness as well as the incident angle. In addition, we further investigate two special cases for practical purposes: the reflected shift with a total reflection and the transmitted shift with a total transmission. Numerical simulations are also performed to verify our analytical results.