Laser power density dependent energy transfer between Tm3+ and Tb3+: tunable upconversion emissions in NaYF4:Tm3+,Tb3+,Yb3+ microcrystals.
Opt Express
; 24(23): 26307-26321, 2016 Nov 14.
Article
in En
| MEDLINE
| ID: mdl-27857366
ABSTRACT
Energy transfer between Tm3+ and Tb3+ dependent on the power density of pump laser was investigated in NaYF4 Tb3+,Tm3+,Yb3+ microcrystals. Under the excitation of a 976-nm near-infrared laser at various power densities, Tb3+-Tm3+-Yb3+ 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 Tm3+ and Tb3+. When the power density of pump laser was low, the energy transfer process from Tm3+ (3F4) to Tb3+ (7F0) occurred efficiently. Upconversion processes in Tm3+ were inhibited, only visible emissions from Tb3+ with green color were observed. When the power density increased, energy transfer from the 3F4 (Tm3+) to 7F0 level (Tb3+) was restrained and population on high energy levels of Tm3+ was increased. Contribution of upconversion emissions from Tm3+ 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 Tm3+ will greatly reduce the population on certain levels for further high-order upconversion processes. The Tb3+-Tm3+-Yb3+ doped phosphors are promising materials for detecting the condition of power density of the invisible near-infrared laser.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Opt Express
Journal subject:
OFTALMOLOGIA
Year:
2016
Type:
Article