Near-Field Coupling Dynamics of Erbium Ions and Surface-Plasmon Polaritons in Plasmonic Metasurfaces

Light-matter interactions play a crucial role in numerous scientific and technological domains, including optics, photonics, optoelectronics, and sensing. In recent decades, there has been a burgeoning interest in leveraging plasmons to augment these interactions. Plasmons exhibit the remarkable ability to substantially amplify the local electromagnetic field, thereby significantly enhancing the intensity of light-matter interactions. Nevertheless, the efficacy of these interactions is frequently impeded by the limited absorption and scattering cross-sections of many materials. The advent of plasmonic nanostructures has provided a means to overcome these limitations by generating highly localized and intense electromagnetic fields. These fields can effectively bolster the interaction between light and matter, leading to novel applications in sensing, energy harvesting, nonlinear optics, and engineering light transport at the sub-wavelength scale. The ability to significantly enhance optical and electromagnetic field intensities around metallic nanostructures, which can alter the excitation and emission properties of locally excited quantum systems, is crucial for the development of next-generation photonic devices. In this work, thin films were fabricated using Er³⁺ doped germane-tellurite glass nanoparticles diluted in Polymethylmethacrylate (PMMA). The PMMA solution was deposited on gold plasmonic gratings, a 20x20 µm sequence of 100 nm wide slits separated by 1000 nm, fabricated using Focused Ion Beam lithography. Confocal optical microscopy and confocal lifetime fluorescence techniques were employed to investigate the coupling mechanisms between surface plasmon polaritons located on the metasurface and the rare-earth ions. It was observed that when Er³⁺ ions are positioned close to the surface, a strong coupling mechanism occurs due to the reduction in the radiative lifetime of the Er³⁺ emitter. This coupling is more evident in smaller nanoparticles, which are closer to the interface. The results demonstrate the potential for developing photonic devices using this platform.<br/>Acknowledgments: <i>This work</i> has been <i>supported</i> by the following <i>Brazilian</i> research <i>agencies</i>:<br/>CAPES, CNPQ (314505/2021-0), and FAPESP (2013/07276-1).