The influence of silver nanoparticles in the Ybsup(3+) - Ersup(3+) energy transfer mechanism of PbO-GeOsub(2) glasses

Abstract

The influence of silver nanoparticles (NPs) on the frequency upconversion due to the energy transfer between erbium (Fr*) and ytterbium (Yb") ions in a co-doped glass is reported for the first time Erbium doped glasses have been studied and used in a variety of photonic applications. Nevertheless, efficient pumping of this ion is limited by the low absorption cross-section of Fr** around 980 nm that can be improved by co-doping the material with Yb* jons [1]. Recently, Er®* doped lead-germanate glasses containing silver NPs were studicd [2], Lead-germanate glasses are excellent materlals ſor photonic applications due to their high mechanical resistance, high chemical durability and thermal Stability, large transmission window (400 to 4500 nm), high refractive index. large nonlinear optical response, and low cutoff phonon energy (400 - 800 cm™) [3]. Besides, these glasses have proved to be good hosts for NPs nucleation [2]. To the basic glass composition 41Pb0-59.0Ge0, (in mol%) we added 0.5 wt% of Erz0z, 3.0 wi% of YbJO, and 1.0 wt% of AgNO;; the samples were obtained melting the starting oxide powers. quenching and annealing during different times to reduce the Ag’ ions to Ag’ in order to nucleate silver NPs. Measurements of (ransmission electron microscopy were performed and the visible upconversion spectrum was measured by optically pumping the sample with a high power CW diode laser emitting 5 W at 980 nm. Emission bands centered at 524, 547, and 659 nm were abserved corresponding 10 *Hi1g — 5o 'S42 — 15, and Fay — 1152 transitions of Fr' ions, respectively. Measurements of the upconversion intensity as a function of the laser power were performed. The influence of silver NPs in the Yb* — Er"” energy transfer mechanism is discussed and is attributed to the Influence of the surface plasmon resonance (associated to the NPs) that favors the emissions in the green region in comparison with the red emission. We remark that in the absence of the silver NPs green and red emissions have almost the same intensity.