Thermally-induced precipitation of gold nanoparticles in phosphate glass: effect on the optical properties of Er3+ ions

• Phosphate glasses doped with Er3+ ions and Au nanoparticles were synthesized. • TEM, optical absorption, and PL spectroscopy analysis were performed. • The influence of Au nanoparticles size on the emission of Er3+ ions was evaluated. • Enhancement of Er3+ photoluminescence in presence of small Au clusters is revealed. • Energy transfer from Au clusters to the excited states of Er3+ ions is presumed. Gold nanoparticles incorporated in glass medium are the object of keen interest due to their unique properties induced by plasmonic effects: coloration, noticeable optical nonlinearity and rare earth ions photoluminescence enhancement. In this work, we examine the structure and optical properties of potassium aluminophosphate glasses doped with Er 3+ ions and Au under the heat treatment below and above glass transition temperature. The heat treatment of the glass at temperatures above T g is shown to facilitate the formation of plasmonic gold nanoparticles and decrease near-infrared luminescence intensity of Er 3+ ions. On the contrary, a similar treatment of the studied glasses at temperatures below T g doesn't induce plasmonic absorption and leads to the intensity enhancement of Er 3+ luminescence. Formation of gold clusters in the glass treated at lower temperatures is supposed to enable the energy transfer process between clusters and rare-earth ions which is expressed in luminescence intensity enhancement.