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Upconversion superburst with sub-2 μs lifetime


The generation of anti-Stokes emission through lanthanide-doped upconversion nanoparticles is of great importance for technological applications in energy harvesting, bioimaging and optical cryptography1,2,3. However, the weak absorption and long radiative lifetimes of upconversion nanoparticles may significantly limit their use in imaging and labelling applications in which a fast spontaneous emission rate is essential4,5,6. Here, we report the direct observation of upconversion superburst with directional, fast and ultrabright luminescence by coupling gap plasmon modes to nanoparticle emitters. Through precise control over the nanoparticle’s local density of state, we achieve emission amplification by four to five orders of magnitude and a 166-fold rate increase in spontaneous emission. We also demonstrate that tailoring the mode of the plasmonic cavity permits active control over the colour output of upconversion emission. These findings may benefit the future development of rapid nonlinear image scanning nanoscopy and open up the possibility of constructing high-frequency, single-photon emitters driven by telecommunication wavelengths.

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Fig. 1: Upconversion amplification through plasmonic nanocavity coupling.
Fig. 2: Theoretical investigations and experimental demonstrations of the gap-plasmon accelerated upconversion process.
Fig. 3: Spectral properties and luminescence enhancement of UCNPs coupled to a gap-plasmon nanocavity.
Fig. 4: Spontaneous emission rate measurements of UCNPs.


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This work is supported by the Singapore Ministry of Education (MOE2017-T2-2-110), the Agency for Science, Technology and Research (A*STAR; grant no. A1883c0011), the National Research Foundation (NRF), the Prime Minister’s Office, Singapore under its Competitive Research Program (award no. NRF-CRP15-2015-03) and under the NRF Investigatorship Program (award no. NRF-NRFI05-2019-0003), and the National Natural Science Foundation of China (no. 21771135).

Author information




Y.W. and X.L. conceived and designed the experiments. X.L., R.A.L.V., C.-W.Q. and J.K.W.Y. supervised the project and led the collaboration efforts. Y.W. and J.X. synthesized the upconversion nanocrystals and silver nanocubes. Y.W., J.X. and E.T.P. conducted the optical experiments. R.A.L.V., J.X., L.L. and H.L. performed theoretical simulations. Y.W. and X.L. wrote the manuscript, with input from all authors.

Corresponding authors

Correspondence to Renaud A. L. Vallée or Xiaogang Liu.

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The authors declare no competing interests.

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Peer review information Nature Nanotechnology thanks Oscar Loureiro and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–12 and refs. 31–32.

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Wu, Y., Xu, J., Poh, E.T. et al. Upconversion superburst with sub-2 μs lifetime. Nat. Nanotechnol. 14, 1110–1115 (2019).

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