Control of the radiative properties via photonplasmon interaction in Er³⁺-Tm³⁺-codoped tellurite glasses in the near infrared region

The novelty of this paper is that it reports on the tuning of the spectral properties of Er³⁺-Tm³⁺ ions in tellurite glasses in the near-infrared region through the incorporation of silver or gold nanoparticles. These noble metal nanoparticles can improve the emission intensity and expand the bandwidth of the luminescence spectrum centered at 1535 nm, covering practically all the optical telecommunication bands (S, C + L and U), and extended up to 2010 nm wavelength under excitation by a 976 nm laser diode. Both effects are obtained by the combined emission of Er³⁺ and Tm ³⁺ ions due to efficient energy transfer processes promoted by the presence of silver or gold nanoparticles for the (Er³⁺) ⁴I_11/2→(Tm³⁺)³H₅, (Er³⁺)⁴I_13/2→ (Tm³⁺) ³H₄ and (Er³⁺)⁴I _13/2→ (Tm³⁺)³F₄ transitions. The interactions between the electronic transitions of Er³⁺ and Tm³⁺ ions that provide a tunable emission are associated with the dynamic coupling mechanism described by the variations generated by the Hamiltonian HDC in either the oscillator strength or the local crystal field, i.e. the line shape changes in the near-infrared emission band. The Hamiltonian is expressed as eigenmodes associated with the density of the conduction electron generated by the different nanoparticles through its collective free oscillations at each resonance frequency of the nanoparticle and their geometric dependence. A complete description of photon-plasmon interactions of noble metal nanoparticles with the Er³⁺ and Tm³⁺ ions is provided.