Advanced manipulation of surface plasmon resonance and the Goos-Hänchen shift in a coupler-free system

We present a surface plasmon resonance (SPR) system designed to operate without the need for a conventional coupler. The proposed SPR configuration consists of a simple two-layer structure with an upper metal layer and a lower atomic medium. Surface plasmon polaritons (SPPs) are readily excited when the real part of the permittivity of the atomic medium falls below unity, enabling an efficient and streamlined excitation process. The atomic medium dynamics is modulated by external fields, such as pump fields and microwaves, facilitating precise control over SPP excitation. We investigate the influence of the atomic medium, analyzing the lifetimes and propagation lengths for both gold and silver layers, while also addressing realistic factors such as dipole momenta, the potential for structural damage, and manufacturing imperfections. Additionally, we explore the Goos-H"anchen (GH) shift of the reflected light, noting an enhanced GH shift that aligns with optimal SPP excitation. Both negative and positive GH shifts are observed, with their directions and magnitudes modifiable through external parameters. This system provides a straightforward and viable method for SPP generation and controlled SPR and GH shift modulation, presenting significant potential for tunable optical devices in telecommunication. We expect these findings to contribute to the development of advanced systems with improved data transmission capabilities.