| Summary: | 碩士 === 國立中正大學 === 物理系研究所 === 104 === The enhanced upconversion luminescence of lanthanide-ion(Ln3+) doped upconversion nanoparticles (UCNPs) is particularly important and highly required for their innumerable applications in fluorescence microscope, bio-imaging, sensing, solid-state lasers, 3D displays, and solar cells.In this study, we investigate the enhancement effect of upconversion fluorescence emission of UNCP by using low refractive index resonant waveguide grating(RWG) when both excitation and extraction resonance occur in the waveguide structure.The method to fabricate one-dimensional grating patterns with nanoporous SiO2, a low refractive index material (n=1.22), using nanoimprint lithography is reported. A guided mode resonant structure is obtained by subsequent sputtering of thin film of high refractive index titanium dioxide (TiO2) on the sample surface, and then NaYF4:Yb3+,Tm3+ nanoparticles are deposited onto the top cladding layer of a RWG structure by dip-coating method.We demonstrate the up-conversion photoluminescence signal generated from the rare-earth nanocrystal coated on top of such RWG structure can be enhanced up to 10^4 times when both excitation and extraction resonance are simultaneously achieved, compared with UCNPs on an non-patterned surface.
Keywords : Low-refractive index , Up conversion, Rare earth, Fluorescence, Guided-mode resonance
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