Enhanced upconversion emission in Er3+-doped tellurite glass containing silver nanoparticles

Er³⁺-doped tellurite glass containing silver nanoparticles (NPs) has been synthesized. Detailed structural and optical characterizations have been carried out. Infrared to visible frequency upconversion (UC) emission has been observed in Er³⁺-doped tellurite glass on pumping with the 976 nm radiation. Further, an enhancement in UC emission intensity of green bands (²H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2) of Er³⁺ ion has been observed up to four times in presence of silver NPs in the glass annealed at 240 °C for 40 h. Though, there is enhancement in intensity in the red band (⁴F_9/2 → ⁴I_15/2) also but it is smaller. The enhancement in fluorescence intensity is attributed to local field effect due to the silver NPs.