Gain-assisted control of Goos-H¨anchen shifts in three-dimensional Dirac semimetals

Dirac materials are of great interest for their tunable Fermi level via electrostatic gating. Here, we investigate the Goos-H¨anchen (GH) shifts for a light beam reflecting from the surface of a threelayered geometry consisting of a three-dimensional (3D) Dirac semimetal (DSM), a gain medium and a lossless dielectric. The gain medium results in significantly amplified lateral shifts in reflection in comparison to ordinary lossless dielectric. We show that these lateral shifts can be finely tuned by varying the rabi frequencies and detunings of the optical fields coupling the transitions of the three-level gain medium. The GH shifts can be further tuned by adjusting the DSM’s Fermi level and layer thicknesses. This enhanced tunability of GH shifts could enable the development of precise optical sensors and switches.