Avalanche effects, where a small input is amplified to produce an enormous output, have found various applications in industries such as lasers and avalanching photodiodes. Photon avalanche, an optical avalanche process that exhibits an extremely nonlinear response in lanthanide-doped materials, has garnered significant interest due to its potential impact on numerous applications, including phase-conjugate imaging, infrared quantum counting, and efficient upconverted lasing. Recently, photon avalanche has been observed in single nanoparticles, opening new possibilities for a wide range of novel applications in environmental sensing, super-resolution imaging, and high-density optical memory. In this talk, I will begin by discussing the photon avalanche behavior of Tm3+-doped NaYF4 nanocrystal. I will focus on unique photophysical properties of these avalanching nanocrystals derived from optical experiments and rate equation modeling. Next, I will introduce the photoswitching behavior of avalanching nanoparticles, and present a proposed photoswitching mechanism associated with color center generation. Lastly, I will introduce several applications of these avalanching nanoparticles including 2D and 3D optical patterning as well as scanning- and widefield-based super-resolution imaging.

Changhwan Lee is a postdoctoral researcher working at Schuck lab at Columbia University. He received his Ph.D. in Mechanical Engineering from Columbia University in 2022. During his PhD, He focused on realizing avalanche effects in lanthanide-doped upconverting nanoparticles and exploring their applications.