The strong blue 476 nm cooperative upconversion luminescence of ytterbium Yb<sup>3+</sup>-Yb<sup>3+</sup> clusters in Yb<sup>3+</sup>-doped oxyfluoride glass was studied. The strength of this luminescence was found to be about 100 times greater than that of Yb(3): zirconium, barium, lanthanum, aluminum, and sodium fluoride glass. Such a large enhancement of cooperative upconversion blue luminescence efficiency results from better coupled Yb<sup>3+</sup>-Yb<sup>3+</sup> clusters, less cross relaxation, increased concentration of Yb<sup>3+</sup> activators, nonsaturation effect, and better upconversion luminescence efficiency. Interestingly, the quadruple-quadruple interaction or exchange interaction seems to exert a stronger action than the dipole-dipole interaction. Meanwhile there apparently exists a large energy transfer from a single Yb<sup>3+</sup> ion or a coupled Yb<sup>3+</sup>-Yb<sup>3+</sup> cluster to a Ho<sup>3+</sup> ion, leading to a dramatic decline in the intensity of the upconversion luminescence of Yb<sup>3+</sup>-Yb<sup>3+</sup> clusters in an Yb<sup>3+</sup>-Ho<sup>3+</sup> codoped oxyfluoride glass.
© 2006 Optical Society of America
Original Manuscript: March 20, 2006
Revised Manuscript: July 25, 2006
Manuscript Accepted: August 19, 2006
Xiaobo Chen, Song Li, Zengfu Song, Weimin Du, Ou Wen, and Naruhito Sawanobori, "Study on strong cooperative upconversion luminescence of ytterbium-ytterbium clusters in oxyfluoride glass," J. Opt. Soc. Am. B 23, 2581-2587 (2006)