Optical refrigeration and superradiance with fluorescent materials
Sushrut Ghonge
PhD Candidate
Department of Physics & Astronomy
University of Notre Dame
Lead halide perovskite nanocrystals and rare-earth-doped solids have near-unity fluorescence quantum yields, which makes them suitable for optical refrigeration. In this seminar, I will show that one can optically cool these materials with incoherent light sources like sunlight just as efficiently as with lasers. I will then present the microscopic mechanism of anti-Stokes photoluminescence, which underlies optical refrigeration. When self-assembled into superlattices and cooled, the same materials cooperatively emit coherent radiation, a phenomenon known as superradiance. I will show how optimizing the geometrical arrangement of nanocrystals makes superradiant emission robust to thermal decoherence and nanocrystal size fluctuations.