Multi-Band Up-Converted Lasing Behavior in NaYF₄:Yb/Er Nanocrystals.

Random lasers have attracted great interests and extensively investigation owing to their promising applications. Here, we explored unambiguously the multi-band up-converted random lasing from NaYF₄:Yb,Er nanocrystals (NCs). NaYF₄:Yb,Er NCs exhibit high effective up-conversion luminescence when they are excited by continuous wave 980 nm laser. We investigated a planar microcavities approach wherein the NaYF₄:Yb,Er NCs showed up-converted lasing behavior. The optical pumping of NaYF₄:Yb,Er NCs by 980 nm pulsed laser excitation exhibited multi-band lasing. The NaYF₄:Yb,Er NCs showed multi-band lasing emission with a line width of 0.2 nm at 540 nm and 0.4 nm at 660 nm. This research promotes potential application in bioimaging and biomedical fields.