Open AccessLaser power density dependent energy transfer between Tm^3+ and Tb^3+: tunable upconversion emissions in NaYF_4:Tm^3+,Tb^3+,Yb^3+ microcrystals
Author(s) -
Xiaojie Xue,
Makhin Thitsa,
Tonglei Cheng,
Weiqing Gao,
Dinghuan Deng,
Takenobu Suzuki,
Yasutake Ohishi
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.026307
Subject(s) - photon upconversion , materials science , laser , power density , optoelectronics , optics , population , excitation , doping , phosphor , power (physics) , physics , demography , quantum mechanics , sociology
Energy transfer between Tm 3+ and Tb 3+ dependent on the power density of pump laser was investigated in NaYF 4 : Tb 3+ ,Tm 3+ ,Yb 3+ microcrystals. Under the excitation of a 976-nm near-infrared laser at various power densities, Tb 3+ -Tm 3+ -Yb 3+ doped samples exhibited intense visible emissions with tunable color between green and blue. The ratio of blue and green emission were determined by energy transfer between Tm 3+ and Tb 3+ . When the power density of pump laser was low, the energy transfer process from Tm 3+ ( 3 F 4 ) to Tb 3+ ( 7 F 0 ) occurred efficiently. Upconversion processes in Tm 3+ were inhibited, only visible emissions from Tb 3+ with green color were observed. When the power density increased, energy transfer from the 3 F 4 (Tm 3+ ) to 7 F 0 level (Tb 3+ ) was restrained and population on high energy levels of Tm 3+ was increased. Contribution of upconversion emissions from Tm 3+ gradually became dominant. The emission color was tuned from green to blue with increasing the power density. Energy transfer processes between low-lying levels of activators, such as Tm 3+ will greatly reduce the population on certain levels for further high-order upconversion processes. The Tb 3+ -Tm 3+ -Yb 3+ doped phosphors are promising materials for detecting the condition of power density of the invisible near-infrared laser.