Collaborative Research: Wavelength-Scalable, Room-Temperature Mid-Infrared Photodetectors Based on Multiphoton-Assisted Tunneling

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Title: Collaborative Research: Wavelength-Scalable, Room-Temperature Mid-Infrared Photodetectors Based on Multiphoton-Assisted TunnelingDetection of mid-infrared (MIR) electromagnetic radiation is of central importance in both fundamental sciences and applied technologies. It finds widespread applications ranging from free-space communication, night vision, nondestructive testing, environmental monitoring, medical diagnostics, spectroscopy, and astronomy research, to the sensitive detection of biomolecular and chemical signals. However, current MIR photodetectors based on narrow-bandgap semiconductors typically suffer from several inherent drawbacks, such as slow response time, high cost, low sensitivity, and most critically, the need for cryogenic cooling that practically prohibits them from portable applications. This collaborative research aims to study a new MIR detection mechanism based on a quantum mechanical phenomenon referred to as multiphoton-assisted tunneling in nanoscale metal–insulator–metal structures toward the development of new plasmo-electronic MIR detectors, which enable ultrafast, efficient, cooling-free, and wavelength-scalable photodetection. This interdisciplinary research interfacing quantum mechanics, photonics, electromagnetics, nanotechnologies, and nanomaterials will provide graduate, undergraduate, and K-12 students with unique multidisciplinary research experiences. The project tightly integrates research, education and community outreach efforts through a series of activities, such as Women in Engineering Program and Early Research Scholars Program, to increase the representation of women and underrepresented minorities in the STEM fields.This collaborative research aims to develop fundamentally new plasmo-electronic nanodevices, which can enrich the functional portfolio of plasmonics in the quantum domain and can lead to ultrafast, highly-efficient, room-temperature, and wavelength-scalable mid-infrared (MIR) photodetectors. We will use innovative nanophotonic and nanomaterial techniques to significantly improve the photon-to-electron conversion efficiency of the multiphoton-assisted tunneling (MPAT) processes occurring in metal–insulator–metal (MIM) plasmonic heterostructures. We will first theoretically model, experimentally characterize, and fully elucidate the optical rectification effect associated with MPAT in the MIR and long-wavelength regimes. Then, we will introduce (1) novel optical nanoantennas and MIM-based optical metasurfaces to enhance the coupling efficiency and localization of light into the MIM tunneling nanojunction, and (2) a new class of two-dimensional (2D) transition metal oxides (TMO) serving as controllable, ultrahigh-quality atomic-scale tunnel barriers. The strong optical nonlinearities induced by tunneling plasmons and the plasmonically-enhanced field localization in these plasmo-electronic MIR photodetectors, consisting of optical nanoantenna or metasurface structures loaded with the 2D TMO tunnel barrier, may enable the state-of-the-art photoconversion quantum yields. The knowledge gained from this research will help establish a new paradigm for detecting and harvesting infrared radiation using plasmonic devices operated in the nonlinear quantum regime, and will shed light on other plasmonically-enhanced MPAT processes, such as high harmonic generation, nonlinear wave mixing, and two-photon absorption, in the infrared regime.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.