The plasmon resonance modes of gold nanoparticles embedded in an erbium doped germanium-tellurite glass are activated using laser lines at 808 and 550 nm in resonance with radiative transitions of Er³⁺ ions. The gold nanoparticles were grown within the host glass by thermal annealing at several times, leading to diameters lower than 1.6 nm. The resonance wavelengths determined theoretically and experimentally are 770 and 800 nm, respectively. The absorption wavelength of nanoparticles was determined by using the Frohlich condition. Gold nanoparticles provide tunable emission resulting in a large enhancement for the ²H_11/2→⁴I_13/2 (emission at 805 nm) and ⁴S_3/2→⁴I_13/2 (emission at 840 nm) electronic transitions of Er³⁺ ions, this is associate with the quantum yield of the energy transfer transition. We observed that up-conversion is favored by the excited-state absorption due to the presence of the gold nanoparticles coupled with the Er³⁺ ions within the glass matrix.