Spectroscopic studies of Er3+ doped Ge-Ga-S glass containing silver nanoparticles

The spectroscopic characteristics of an erbium-doped Ga10Ge25S65 (GGS) glass containing silver were studied and compared with that of an erbium-doped GGS glass without silver. The optical absorption spectra revealed the surface plasmon resonance (SPR) related characteristic of silver nanoparticles (NPs) around 490 nm. Enhancement of Er3+ luminescence was observed for a broad excitation wavelength region, and the largest enhancement was observed for the excitation at 488 nm, which is near the peak of SPR of silver NPs in GGS glass and in resonance with Er3+ ions. For the excitation at 405 nm, enhancement of luminescence from both GGS host and Er3+ ions was observed. A smaller enhancement was observed for a two-step upconversion luminescence excited at 801 nm. The observed enhancement of Er3+ luminescence is mainly attributed to the local field effects: the SPR of Ag NPs causes an intensified electromagnetic field around NPs, resulting in enhanced optical transitions of Er3+ ions in the vicinity.