Control of silver clustering for broadband Er³⁺ luminescence sensitization in Er and Ag co-implanted silica

Highlights: • 1.54 µm Er emission enhancement is achieved in Er and Ag coimplanted silica. • Photosensitization process occurs in presence of ultra-small Ag clusters. • Ag-driven energy transfer is proposed as the Er sensitization mechanism. • Ag clustering can be controlled by suitable post-implantation thermal annealing. - Abstract: In this work, the optical properties of Er and Ag co-implanted silica slabs were investigated in order to shed light on the observed improvement of the rare-earth emission properties through a sensitization process activated by Ag implantation. A full ion implantation approach was adopted since it represents an effective way to create a thin doped layer, where luminescent Er ions can interact with Ag-related sensitizing species. The results evidenced that the sensitization process is effectively promoted in presence of Ag ultra-small structures, like few-atom aggregates or multimers, which can be already formed at the early stages of the metal clustering process. On the other hand, the precipitation of large, plasmonic clusters, occurring at high temperature post-Ag implantation annealing, produces a decrease of the fluorescence enhancement effect. Furthermore, it is suggested that the overall sensitization mechanism originates from an Ag-Er energy transfer that determines the possibility of a broadband photostimulation of the rare-earth ions, even by pumping in non-resonant excitation condition. Thanks to these features, the investigated Er and Ag co-implanted system can be considered for the realization of high-performing optical amplifiers in waveguide.