Unprecedented multiphonon vibronic transitions of erbium ions on copper nanoparticle-containing tellurite glasses.

Erbium-doped tellurite glass containing copper nanoparticles showed multi-band emission of one particular transition (4I9/2→4I15/2, at 980 nm) due to electron-lattice coupling. The present study reports the vibronic transitions of intraconfigurational 4fn transitions of Er3+ ions in a tellurite host matrix at room temperature for the first time. The mechanisms of multiphoton transitions and the effect of laser heating are discussed here. This unprecedented behavior enables the design of a plethora of different applications spanning from tunable emission in the near infrared, such as lasers for bioimaging and biomedical fields, to energy conversion by thermophotovoltaic conversion of thermal radiation.