Plasmonic structure induced giant Goos-Hänchen shifts in a four-level quantum system

In this study, we explore the role of plasmonic nanostructure on Goos-Hänchen (GH) shifts of the reflected and transmitted probe beams. We suppose that the intracavity medium is consisted of four-level quantum system and plasmonic nanostructure which located at distance d from quantum system. We show that in the presence of plasmonic nanostructure the giant GH shifts obtain in reflected and transmitted light. Moreover, it is finding that the group velocity of the reflected and transmitted light can be switched from slow to fast light simultaneously.