Lawrence Berkeley National Laboratory

Photon avalanching nanoparticles (ANPs) exhibit extremely nonlinear upconverted emission valuable for subdiffraction imaging, nanoscale sensing, and optical computing. Avalanching has been demonstrated with Tm³⁺-, Pr³⁺-, or Nd³⁺-doped nanocrystals, but their emission is limited to a few wavelengths and materials. Here, we utilize Gd³⁺-assisted energy migration to tune the emission wavelengths of Tm³⁺-sensitized ANPs and generate highly nonlinear emission from Eu³⁺, Tb³⁺, Ho³⁺, and Er³⁺ ions. The upconversion intensities of these spectrally discrete ANPs scale with nonlinearity factor s = 10-17 under 1064 nm excitation at power densities as low as 7 kW cm^-2. This strategy for imprinting avalanche behavior on remote emitters can be extended to fluorophores adjacent to ANPs, as we demonstrate with CdS/CdSe/CdS core/shell/shell quantum dots. ANPs with rationally designed energy transfer networks provide the means to transform conventional linear emitters into a highly nonlinear ones, expanding the use of photon avalanching in biological, chemical, and photonic applications.