RII Track-4: van der Waals polaritonics for mid-infrared light emitters

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The mid-infrared (mid-IR) is part of optical spectrum that is invisible to the naked eye but important for a wealth of technologies, including biochemical sensing, gas monitoring, thermal illumination and energy control, security and defense, and many others. Despite these vital applications, research and development in the mid-IR have been stymied due to the sparsity of efficient light sources in this wavelength range. This fellowship project aims to develop bright mid-IR light sources by coupling nanometer scale material dots (quantum dots) with propagating nanoscale optical waves (polaritons). By controlling the properties of the polaritons in layer materials, the research team plan to enhance the intensity of light emitted from quantum dots. The PI will collaborate with researchers at the University of Texas at Austin (UT Austin) to synthesis quantum dots-polariton structures and to perform the mid-IR optical characterizations. This fellowship project is expected to develop useful mid-IR light sources that will benefit a broad range of applications listed above. The project will also broaden the research capabilities of the PI and Auburn University in IR optoelectronics and quantum-engineered material synthesis, as well as establish long-term collaborations between Auburn University and other institutions including UT Austin.The primary goal of the project is to develop bright and controllable light emitters for the technically important mid-IR spectra range where light wavelength spans from 3 to 20 m. For this purpose, the PI proposes to incorporate current quantum dots mid-IR emitters with polaritonic van der Waals (vdW) materials. Polaritons in vdW materials are highly confined and relatively low-lossy, therefore possess high photonic density of states to enhance the mid-IR light emission by increasing the radiative recombination rate of electrons in quantum dots. The PI and his collaborators will grow mid-IR semiconductor quantum dots using the state-of-the-art molecular beam epitaxy at UT Austin. The research team will then fabricate vdW polaritonic materials on top of the quantum dots and fine tune the top surface structure to optimize light emission into the free space. Graphene and configurable vdW heterostructures will be involved to implement dynamic tunability for the light emitters. The quantum dot-polariton emitters will finally be characterized by mid-IR photoluminescence spectroscopy to test the light emission performance. The successful demonstration of this project will deliver bright and dynamically tunable mid-IR light sources and complement current knowledge in light-matter interactions with a better understanding of quantum dot – polariton interactions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.