Li, Z. & Yin, Y. Stimuli‐responsive optical nanomaterials. Adv. Mater. 31, 1807061 (2019).
Blum, A. P. et al. Stimuli-responsive nanomaterials for biomedical applications. J. Am. Chem. Soc. 137, 2140–2154 (2015).
Blblocke, G. & Grabmaier, B. A General Introduction to Luminescent Materials (Springer, 1994).
Liang, Y. et al. Migrating photon avalanche in different emitters at the nanoscale enables 46th-order optical nonlinearity. Nat. Nanotechnol. 17, 524–530 (2022).
Lee, C. et al. Giant nonlinear optical responses from photon-avalanching nanoparticles. Nature 589, 230–235 (2021).
Wang, C., Wen, Z., Pu, R. & Zhan, Q. Giant optical nonlinear response up to 60th-order induced by the ytterbium energy relay mediated photon avalanches. Laser Photon. Rev. 18, 2400290 (2024).
Eaton, D. F. Nonlinear optical materials. Science 253, 281–287 (1991).
Martins, J. C. et al. Upconverting nanoparticles as primary thermometers and power sensors. Front. Photon. 3, 1037473 (2022).
Su, Q. et al. Six-photon upconverted excitation energy lock-in for ultraviolet-C enhancement. Nat. Commun. 12, 4367 (2021).
Haase, M. & Schäfer, H. Upconverting nanoparticles. Angew. Chem. Int. Ed. 50, 5808–5829 (2011).
Liu, Q. et al. Single upconversion nanoparticle imaging at sub-10 W cm−2 irradiance. Nat. Photon. 12, 548–553 (2018).
Auzel, F. Upconversion and anti-stokes processes with f and d ions in solids. Chem. Rev. 104, 139–174 (2004).
Zhang, M. et al. Lanthanide-doped KMgF3 upconversion nanoparticles for photon avalanche luminescence with giant nonlinearities. Nano Lett. 23, 8576–8584 (2023).
Szalkowski, M. et al. Advances in the photon avalanche luminescence of inorganic lanthanide-doped nanomaterials. Chem. Soc. Rev. 54, 983–1026 (2025).
Wu, H. et al. Versatile cascade migrating photon avalanches for full-spectrum extremely nonlinear emissions and super-resolution microscopy. Adv. Photon. 6, 056010 (2024).
Zhu, Z. et al. Three-dimensional, dual-color nanoscopy enabled by migrating photon avalanches with one single low-power CW beam. Sci. Bull. 69, 458–465 (2024).
Denkova, D. et al. 3D sub-diffraction imaging in a conventional confocal configuration by exploiting super-linear emitters. Nat. Commun. 10, 3695 (2019).
Liu, C. et al. Sub-60-nm isotropic 3D super-resolution microscopy through self-interference field excitation. Optica 11, 1324–1333 (2024).
Wang, C. et al. Tandem photon avalanches for various nanoscale emitters with optical nonlinearity up to 41st‐order through interfacial energy transfer. Adv. Mater. 36, 2307848 (2024).
Dudek, M. et al. Size‐dependent photon avalanching in Tm3+ doped LiYF4 nano, micro, and bulk crystals. Adv. Opt. Mater. 10, 2201052 (2022).
Dudek, M. et al. Understanding Yb3+-sensitized photon avalanche in Pr3+ co-doped nanocrystals: modelling and optimization. Nanoscale 15, 18613–18623 (2023).
You, W., Tu, D., Zheng, W., Huang, P. & Chen, X. Lanthanide-doped disordered crystals: site symmetry and optical properties. J. Lumin. 201, 255–264 (2018).
Wisser, M. D. et al. Strain-induced modification of optical selection rules in lanthanide-based upconverting nanoparticles. Nano Lett. 15, 1891–1897 (2015).
Dong, H., Sun, L.-D. & Yan, C.-H. Local structure engineering in lanthanide-doped nanocrystals for tunable upconversion emissions. J. Am. Chem. Soc. 143, 20546–20561 (2021).
Wisser, M. D. et al. Enhancing quantum yield via local symmetry distortion in lanthanide-based upconverting nanoparticles. ACS Photon. 3, 1523–1530 (2016).
Goldner, P. & Pelle, F. Photon avalanche fluorescence and lasers. Opt. Mater. 5, 239–249 (1996).
Bednarkiewicz, A., Chan, E. M., Kotulska, A., Marciniak, L. & Prorok, K. Photon avalanche in lanthanide doped nanoparticles for biomedical applications: super-resolution imaging. Nanoscale Horiz. 4, 881–889 (2019).
Villanueva-Delgado, P., Krämer, K. W., Valiente, R., de Jong, M. & Meijerink, A. Modeling blue to UV upconversion in β-NaYF4:Tm3+. Phys. Chem. Chem. Phys. 18, 27396–27404 (2016).
Majak, M., Misiak, M. & Bednarkiewicz, A. The mechanisms behind the extreme susceptibility of photon avalanche emission to quenching. Mater. Horiz. 11, 4791–4801 (2024).
Naccache, R., Yu, Q. & Capobianco, J. A. The fluoride host: nucleation, growth, and upconversion of lanthanide‐doped nanoparticles. Adv. Opt. Mater. 3, 482–509 (2015).
Wang, F., Wang, J. & Liu, X. Direct evidence of a surface quenching effect on size-dependent luminescence of upconversion nanoparticles. Angew. Chem. Int. Ed. 49, 7456–7460 (2010).
Würth, C., Fischer, S., Grauel, B., Alivisatos, A. P. & Resch-Genger, U. Quantum yields, surface quenching, and pblockivation efficiency for ultrasmall core/shell upconverting nanoparticles. J. Am. Chem. Soc. 140, 4922–4928 (2018).
Lage, M. M., Moreira, R. L., Matinaga, F. M. & Gesland, J.-Y. Raman and infrared reflectivity determination of phonon modes and crystal structure of Czochralski-grown NaLnF4 (Ln = La, Ce, Pr, Sm, Eu, and Gd) single crystals. Chem. Mater. 17, 4523–4529 (2005).
He, E. et al. Investigation of upconversion and downconversion fluorescence emissions from β-NaLn1F4:Yb3+, Ln23+ (Ln1 = Y, Lu; Ln2 = Er, Ho, Tm, Eu) hexagonal disk system. Mater. Res. Bull. 48, 3505–3512 (2013).
Tu, D. et al. Breakdown of crystallographic site symmetry in lanthanide‐doped NaYF4 crystals. Angew. Chem. Int. Ed. 4, 1128–1133 (2013).
Dong, H. et al. Efficient tailoring of upconversion selectivity by engineering local structure of lanthanides in NaxREF3+x nanocrystals. J. Am. Chem. Soc. 137, 6569–6576 (2015).
Arteaga Cardona, F. et al. Dramatic impact of materials combinations on the chemical organization of core–shell nanocrystals: boosting the Tm3+ emission above 1600 nm. ACS Nano 18, 26233–26250 (2024).
Liu, Y. et al. Amplified stimulated emission in upconversion nanoparticles for super-resolution nanoscopy. Nature 543, 229–233 (2017).
Liang, L. et al. Continuous-wave near-infrared stimulated-emission depletion microscopy using downshifting lanthanide nanoparticles. Nat. Nanotechnol. 16, 975–980 (2021).
Lee, C. et al. Indefinite and bidirectional near-infrared nanocrystal photoswitching. Nature 618, 951–958 (2023).
Zhou, J. et al. Activation of the surface dark-layer to enhance upconversion in a thermal field. Nat. Photon. 12, 154–158 (2018).
Xu, H. et al. Anomalous upconversion amplification induced by surface reconstruction in lanthanide sublattices. Nat. Photon. 15, 732–737 (2021).
Lamon, S., Yu, H., Zhang, Q. & Gu, M. Lanthanide ion-doped upconversion nanoparticles for low-energy super-resolution applications. Light Sci. Appl. 13, 252 (2024).
Willig, K. I., Keller, J., Bossi, M. & Hell, S. W. STED microscopy resolves nanoparticle blockemblies. New J. Phys. 8, 106 (2006).
Chivian, J. S., Case, W. & Eden, D. The photon avalanche: a new phenomenon in Pr3+‐based infrared quantum counters. Appl. Phys. Lett. 35, 124–125 (1979).
Marciniak, L., Bednarkiewicz, A. & Elzbieciak, K. NIR–NIR photon avalanche based luminescent thermometry with Nd3+ doped nanoparticles. J. Mater. Chem. C 6, 7568–7575 (2018).
Fardian-Melamed, N. et al. Infrared nanosensors of piconewton to micronewton forces. Nature 637, 70–75 (2025).
Casar, J. R. et al. Upconverting microgauges reveal intraluminal force dynamics in vivo. Nature 637, 76–83 (2025).
Skripka, A. et al. Intrinsic optical bistability of photon avalanching nanocrystals. Nat. Photon. 19, 212–218 (2025).
Pan, B. et al. Sidelobe-free deterministic 3D nanoscopy with λ/33 axial resolution. Light Sci. Appl. 14, 168 (2025).