ABSTRACT
Rare earth-doped oxyfluoride glass-ceramic (GC) demonstrate the physical, chemical, and mechanical stabilities of oxide glass and excellent optical properties of fluoride crystals and is regarded as a potential material for developing advanced optical devices. In the present study, Li+-doped NaYF4:Er,Yb GC was prepared by the traditional melt-quenching method. Upon the excitation of single 980 and 1550 nm lasers, the upconversion (UC) luminescence intensities of green and red emission were enhanced due to the introduction of the crystal field symmetry reducing available Li+ ions of the use of dual-wavelength (980 and 1550 nm) co-excitation and could further enhance the UC luminescence intensity owing to its synergetic effect, which is suitable for the design of all-optical logic gates. The all-optical UC logic gates and complex logic operations ("YES + OR", "INH + YES", "XOR + YES", and "INH + AND + YES + OR") are designed by taking the two excitation sources as input signals and UC emission as output signals. The results provide a novel strategy to enhance UC luminescence and further information for the design of novel photonic logic devices for future optical computing technologies.
ABSTRACT
The rational development of multicolor upconversion (UC) luminescent materials is particularly promising for achieving high-tech anti-counterfeiting and security applications. Here, an Ho3+ and Yb3+ ion co-doped KLa(MoO4)2 material can achieve multicolored UC luminescence by thermally manipulating the electron transition process, which could be developed to execute advanced optical anti-counterfeiting applications. The emission color of this material turns from bright green to deep orange with the temperature controlled from 85 K to 240 K in a cryogenic environment. The maximum absolute sensitivity and relative sensitivity of this temperature-sensing material based on non-thermally coupled levels of Ho3+ ions reached 0.049 K-1 and 4.6% K-1. And utilizing the thermochromic luminescence properties and high sensitivity for low temperature of the KLa(MoO4)2:Yb3+/Ho3+ UC material, we created KLa(MoO4)2:Yb3+/Ho3+ fluorescent security inks and UC photonic barcodes to realize novel visual reading and digital recognition dual-mode anti-counterfeiting in a secure manner. These results may provide useful enlightenment for the design and modulation of high-sensitivity temperature-sensing materials for high-level anti-counterfeiting applications.
