Resonant Control and Enhancement of Upconversion Luminescence of NaYF₄:Yb,Er Nanoparticles on Metal Gratings

Abstract

Large plasmonic enhancements of upconversion luminescence (UCL) of lanthanide‐doped materials are achieved usually by plasmon resonances at excitation wavelengths. Here, moderately high‐Q plasmon resonance modes at emission wavelengths are used to control and enhance the UCLs of NaYF4:Yb,Er nanoparticles on metal gratings. It is experimentally shown that, as Bloch‐type plasmon resonance modes locate at/near the green‐ (≈540 nm) or red‐emission (≈654 nm) wavelengths, the UCL is strongly enhanced (e.g., up to ≈117 times for the green and ≈272 times for the red), as well as large modifications of the green‐to‐red intensity ratios. The enhancement factors are comparable to or even much larger than those for plasmon resonances at excitation wavelengths reported in literatures. Importantly, it is disclosed that localized plasmon resonance modes in grooves of the metallic gratings, usually invisible in far‐field characterization, can be excited by the emission dipoles (Er3+) in vicinity (i.e., in the near‐field) to play an important role on UCL emissions. It is also inferred that the plasmon resonance modes at the emission wavelengths improve not only the Purcell factor for UCL emissions but also the energy transfer (Yb3+→Er3+) rates in excitation.

Regulative control and enhancement of multi-color upconversion luminescence with DBR cavities

“…In the study, a Ln 3+ -doped nanomaterial of β-NaYF 4 : Yb 3+ (18%)/Er 3+ (2%) upconversion nanoparticles (UCNPs) is used, synthesized following a co-precipitation procedure [35,36]. Figure 1(a) schematically illustrates structure of the DBR cavity on a glass substrate, in which the UCNPs are embedded in the cavity region sandwiched between two symmetric DBRs.…”

“…In the study, UCL spectra of the UCNPs are characterized by focusing an excitation beam from a diode laser (975 nm in wavelength) onto the sample surface and collecting the emitted light by the same focal lens (NA = 0.45) for spectral analyzing, as illustrated in figure 1(d) [28,36]. The focusing spot size is estimated to be ∼80 µm in diameter.…”

Enhanced upconversion based on surface plasmon resonance in a multilayered UCNPs-metamaterial absorber

“…Metamaterial is the material engineered to have extraordinary property, such as negative index [1], plasmon induced transparency [2,3] and perfect absorption [4]. The metamaterial with high absorption can lead to strong local field enhancement, which is very promising in improving the upconverison efficiency of the lanthanide doped upconversion nanoparticles [5][6][7]. However, rare attention was paid into the plasmon enhanced upconversion by metamaterial with high absorption and the related mechanism.…”

Enhancement of upconversion photoluminescence in phosphor nanoparticle thin films using metallic nanoantennas fabricated by colloidal lithography

“…An alternative route to tailoring LSPRs relies on the use of lithographic methods. Indeed, a variety of techniques have been used for this purpose, including laser interference, 34 nanoimprint, 33,41 electron beam [42][43][44][45] or a combination of lithography, chemical etching, 35,46 and thermal evaporation. 33,34 Although, these techniques allow the fabrication of nanostructures with fine precision, they have the disadvantage of requiring costly steps.…”