Quantum-plasmonic interaction: Emission enhancement of Er ³⁺-Tm³⁺ co-doped tellurite glass via tuning nanobowtie

Metallic nanobowtie is well known as a suitable structure for development of antennas that can be integrated on wide number of devices, especially in optical communications. Such feature is achieved due the presence of surface plasmon polariton (SPP) that provides a great charge density on nearby region from its tips. Considerable studies have described theoretical and experimentally the influence of gap between tips on radiation emission, once this parameter may improve the local field, as such length decrease. In optical regime, the emission enhancement is due the quantum-plasmonic interaction created from tips region (localized field) and the transition levels from rare earth ion of erbium (Er³⁺) and thulium (Tm³⁺). However, metallic nanobowtie with absence of gap still deserve attention, because in addition to present similar properties from regular case as previously mentioned, can also interacts with different systems, like gain materials, that can be embedded thermically into the substrate. Rare earth ion is one of the remarkable and suitable for our proposition, not only for the enhancement on measured intensity, but also its easiness to implement it on glasses, which constitute the main type of substrate adopted on plasmonic structures. In this work we performed the analysis of effects due implementation of Er³⁺ and Tm³⁺ ions into BK7 glass over a pattern of nanobowtie on absence of gap between its tips, fabricated by focused ion beam (FIB) technique from gold (Au) films. The bowties were vertically excited by an Argon laser (Ar) which wavelength is 488 nm. Furthermore, computational simulations based on finite element method (FEM), were performed to verify the dependence of nanobowtieas geometry over the electric field along its symmetry axis.