Optically tunable Goos-Hänchen shift in a metal-clad waveguide structure containing a cold atomic ensemble

Abstract

We propose an efficient scheme to manipulate the Goos-Hänchen (GH) shift of the reflected beam in a metal-clad waveguide structure, where a cold atomic ensemble with four-level ladder-type configuration acts as the substrate. Due to the quantum interference in the two decay pathways from the two upper closely lying levels, spontaneously generated coherence (SGC) is generated. It is demonstrated that the reflected GH shift is sensitively dependent upon the SGC effect. The controllable GH shift originates from the competition between the internal damping and radiation damping. Furthermore, in the presence of SGC, the magnitude, sign, and position of the GH shift can be effectively controlled via adjusting the intensity and detuning of the trigger field. Our scheme may have potential applications in all-optical switching and optical sensor.