Enhanced Goos–Hänchen shift at normal incidence using Tamm plasmon polaritons

Abstract The Goos–Hänchen (GH) shift, a lateral displacement of an optical beam under total internal reflection, generally requires oblique incidence and remains reciprocal. Achieving a non-reciprocal GH shift at normal incidence via the magneto-optical effect is of great importance for ultra-compact integrated photonic systems, yet its typically weak magnitude has hindered practical implementation. Here, we propose a novel strategy that exploits the strong field localization of Tamm plasmon polaritons in a simple multilayer structure, enabling orders-of-magnitude enhancement of the non-reciprocal GH shift in both reflection and transmission at normal incidence. Furthermore, by incorporating parity-time symmetry, we demonstrate that this enhancement can be further increased. Our work establishes a compact and versatile platform for realizing pronounced non-reciprocal beam shifts, opening promising pathways toward on-chip photonic devices such as isolators, switchers, and sensors.