Tunable bandgap and luminescence properties by engineering exciton coupling in Ag NP embedded Er³⁺ bismuth tellurite glass system

Glass compositions of 20Li₂O-xBi₂O₃-(78-x)TeO₂-1Er₂O₃-1Ag were fabricated to explore exciton-phonon and exciton-plasmon coupling for laser technology. The Urbach tails analysis indicates increased exciton-phonon coupling at x < 11 mol%, inferred from the disorder parameter E_o. The Elliott-Washington hydrogenic excitonic model highlights a decrease in optical bandgap (E_g) at x < 11 mol% before reaching a maximum at x = 11 mol%. Exciton-phonon coupling was analyzed using the Huang-Rhys parameter S. Fano resonance analysis suggests enhanced exciton-plasmon coupling at x = 5 mol%, leading to enhanced luminescence intensity (²H_11/2). Methods including coupling polarizability α(λ), Purcell factor \({F}_{\text{p}}\) , and Lamb shift \({{\Delta }}_{c}\) were employed to analyze the exciton-plasmon coupling. The ability to fine-tune optical properties is crucial for tailored laser emissions, applicable in light-emitting devices and material processing, where precise laser characteristics are essential.