Lanthanide-doped nanomaterials exhibit complex photophysical dynamics that give rise non-linear optical processes such as photon upconversion, which can be leveraged for solution-processable optoelectronics and imaging through biological tissue. I will discuss the high-throughput development and application of a new class of upconverting nanoparticle that uses an avalanche-like energy looping mechanism to non-linearly amplify the population of its excited states.  This unique mechanism, excited at 1064 nm, enables such “energy-looping nanoparticles” (ELNPs) to be imaged through millimeters of brain tissue. Furthermore, by coupling ELNPs to the whispering gallery modes of polystyrene microspheres, the ELNP resonators achieve sufficient optical gain to exhibit continuous-wave, anti-Stokes lasing that is stable for hours under room temperature operation. We use correlative optical and electron microscopy to uncover the chemical and structural factors that govern the assembly of efficient upconversion microlasers. We demonstrate that microlasers with record low thresholds and high quality factors can be fabricated with high fidelity by controlling the number of layers, surface charge, and ligand coordination of the nanoparticles as they assemble onto cavity surfaces. Finally, we demonstrate that these microlasers operate and can be used to measure temperature even in complex biological media such as serum and through tissue-mimicking phantoms. These results suggest that energy looping microlasers, which are smaller than red blood cells, may be applied to in vivo sensing and optogenetic stimulation through tissue.

Discovery and controlled assembly of lanthanide-doped nanoparticles for ultra-low-threshold upconversion microlasers

2019 Fall National Meeting

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