Blue cooperative luminescence in Yb3+-doped tellurite glasses excited at 1.064 μm

Laser oscillation of Yb³⁺:Er³⁺ co-doped phosphosilicate microsphere [invited]

A fiber-taper-microsphere-coupled system was used to research the characteristics of laser oscillation and upconversion luminescence of Yb3+:Er3+ co-doped phosphosilicate (YECP) microspheres. The YECP microspheres were fabricated by melting the end of phosphosilicate filaments. Single- and multimode laser oscillation at 1535-1565 nm within the C-band were obtained. In addition, the output power of the single-mode laser at 1545.5 nm can be as high as 48.98 μW, which was achieved under pump power of 9.63 mW, and the side-mode suppression ratio was 51.49 dB. Upconversion fluorescence of Er3+ at 521, 532, and 544 nm also were measured, and the pump power dependence was studied. The fluorescence intensity was lower than that of Yb3+:Er3+ co-doped silica and oxyfluoride glass ceramic microspheres. Moreover, the physical mechanism of upconversion suppression and laser oscillation enhancement observed in our experiment was presented, which is beneficial to the preparation of rare-earth-doped microcavity lasers.

Intense green and red upconversion emissions from Ho(3+) in presence of Yb(3+) in Li:TeO2 glass

Weak visible emission is observed at 545 nm and 660 nm on 976 nm excitation of Ho(3+) ions doped in tellurite glass. Addition of ytterbium to the doped glass causes a large increase in intensity of the green and the red emissions. In addition to these two new emissions of Ho(3+) one in the blue and the other in the NIR region are also observed. This increase in intensity is ascribed to energy transfer from ytterbium ions to holmium ions. Rate equation model has been proposed to study the upconversion emission and its dependence on pumping power. Possible upconversion mechanisms for these emissions are also discussed. Effect of changing the concentration of Yb(3+) on the emission intensity, lifetime and full width at half maximum (FWHM) in (5)F(4)((5)S(2)) --> (5)I(8) transition of Ho(3+) in codoped sample has also been studied.

Structural and chemical characterization of Yb2O3-ZrO2 system by HAADF-STEM and HRTEM

ZrO2:Yb3+ nanocrystalline phosphors with high concentrations of ytterbium ions were prepared using the sol-gel method. X-ray diffraction, high-angle annular-dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy (HRTEM) were used to characterize the nanocrystalline phosphors annealed at 1000 degrees C. Unit-cell distortion and changes in the crystalline structure of the monoclinic zirconia to tetragonal zirconia, and subsequently cubic zirconia, were observed with increased Yb concentration. Yb ions were randomly distributed into the lattice of the crystalline structure. No segregation of Yb2O3 phase was observed. The substitution of Zr atoms by Yb atoms on different crystalline phases was confirmed by the experimental results and theoretical simulations of HRTEM and HAADF-STEM.

Blue Cooperative Luminescence In Yb3+-Doped Barium Gallogermanate Glass Excited At 976 nm

The Yb3+-doped barium gallogermanate glass has been prepared via the conventional melt method. The absorption spectra, the near infrared emission spectra, the upconversion emission spectra and the differential scanning calorimetry have been measured. Bright blue upconversion emission centered at 476 nm has been observed under the 976 nm laser diode excitation at room temperature. The blue upconversion emission mechanism has been discussed on the blue emission intensity and the measured lifetime. The slope of the log-log plot of the blue emission intensity versus the pump power is equal to 1.98, and the blue luminescence decay time is half of the near infrared fluorescence decay time, confirming that the blue emission comes from Yb3+-Yb3+ pairs cooperative upconversion mechanism. The result of differential scanning calorimetry suggests that this type of glass is suitable as a potential candidate for fiber drawing.