Abstract

The ultraviolet upconversion luminescence of the ${\mathrm{Tm}}^{3+}$ ion sensitized by the ${\mathrm{Yb}}^{3+}$ ion in fluoride glass as excited by a $975\mathrm{nm}$ diode laser was studied. Two typical ultraviolet upconversion luminescence lines positioned at 290.6 and $362.0\mathrm{nm}$ were found and could be identified as the fluorescence transitions of ${}^{1}I_6\to {}^{3}H_6$ and ${}^{1}D_2\to {}^{3}H_6$, respectively. The elaborative measurement of the variation of upconversion luminescence intensity F as a function of the $975\mathrm{nm}$ pumping laser power P has proven that the luminescence lines result from five-photon and six-photon upconversion processes, respectively. To our best knowledge, the finding of six-photon ultraviolet upconversion luminescence is original. Moreover, a novel characteristic upconversion luminescence saturation phenomenon was observed, as the $\log F–\log P$ curve of upconversion fluorescence versus pumping laser power is a straight line, while the slopes of these $\log F–\log P$ plots are apparently smaller than the value determined by the normal multiphoton relation. When the pumping laser spot was increased, the slopes were enhanced noticeably from small values to those that are equal to or near what a normal multiphoton relation would determine. The mechanism of this characteristic saturation phenomenon is the energy expansion resulting from the energy resonant migration among ${\mathrm{Yb}}^{3+}$ ions.

© 2007 Optical Society of America

Study on strong cooperative upconversion luminescence of ytterbium-ytterbium clusters in oxyfluoride glass

Xiaobo Chen, Song Li, Zengfu Song, Weimin Du, Ou Wen, and Naruhito Sawanobori
J. Opt. Soc. Am. B 23(12) 2581-2587 (2006)

Intense ultraviolet upconversion luminescence from hexagonal NaYF₄:Yb³⁺/Tm³⁺ microcrystals

Guofeng Wang, Weiping Qin, Lili Wang, Guodong Wei, Peifen Zhu, and Ryongjin Kim
Opt. Express 16(16) 11907-11914 (2008)

Excitation scheme for the upper energy levels in a Tm:Yb:BaY₂F₈ laser crystal

M. A. Noginov, M. Curley, P. Venkateswarlu, A. Williams, and H. P. Jenssen
J. Opt. Soc. Am. B 14(8) 2126-2136 (1997)

Selective sensitization of 480-nm blue upconversion by Tm³⁺–Er³⁺ energy transfer in tellurite glass

S. Tanabe, K. Suzuki, N. Soga, and T. Hanada
J. Opt. Soc. Am. B 11(5) 933-942 (1994)

Two-step upconversion luminescence in Yb:Tb:YSGG crystal

M. A. Noginov, P. Venkateswarlu, and M. Mahdi
J. Opt. Soc. Am. B 13(4) 735-741 (1996)