Visible Upconversion in Rare-earth Ion-doped NaYF4 Crystals and Nanocoloids

D.N. Patel, M. Jumper, D.M. Wright III, S. Sarkisov
Oakwood University, US

Keywords: crystals, nanocolloids, rare-earth


Nano-colloids and nano-crystals doped with rare-earth elements have recently attracted a lot of attention in the scientific community. This attention is due to unique physical, chemical and optical properties attributed to nanometer size of the particles. They have great potential of being used in applications from new types of lasers, blue and UV ones, display monitors, optical communications and fluorescence imaging. The photonic crystal fiber was filled with nano-colloids. The phosphors were prepared by using simple co-precipitation synthetic method. The initially prepared phosphor has very week or no fluorescence signals. Nano-colloids were obtained using methanol as solvents and they were utilized as laser filling medium in photonic crystal fibers. Under 980 nm laser excitation ytterbium and erbium co-doped NaYF4 phosphor showed upconversion signals at 408 nm, 539 nm and 655 nm, the ytterbium and holmium co-doped NaYF4 phosphor showed upconversion at 540 nm, 646 nm and 751 nm and the ytterbium and thulium co-doped NaYF4 phosphor showed upconversion at 376 nm, 476 nm, 647 nm, 689 nm and 802 nm. The reported nano-colloids are good candidates for fluorescent biosensing applications and also as a new laser filling medium in fiber lasers.