Ultrafast THz-IR Quantum Optoelectronics with Non-Equilibrium 2D Materials and Inverse-Designed Electromagnetic Structures

Nontechnical Description: Many important signals in the world occur at terahertz and infrared frequencies. These signals can reveal chemical fingerprints, biological structure, security-relevant materials, and high-speed communication waveforms, but today’s detectors and signal-processing components are often bulky, slow, power-hungry, or insufficiently sensitive. This project will develop a new class of compact, ultrafast sensors and signal converters by combining atomically thin materials with specially designed electromagnetic structures. The atomically thin materials provide quantum responses that can be tuned by light and electrical fields, while the engineered structures concentrate weak terahertz and infrared fields into very small regions where they can be detected or converted efficiently. The project will advance the national interest by supporting progress in science and engineering and by enabling technologies relevant to health, security, communications, and environmental monitoring. Potential long-term applications include compact infrared chemical sensors, label-free biomedical imaging tools, terahertz components for future wireless systems, and lightweight sensors for remote detection. The project will also train students at the intersection of physics, electrical engineering, nanofabrication, computational design, and ultrafast spectroscopy. Educational materials, benchmark datasets, and reference device designs will be shared with the broader research community to accelerate progress in this emerging area. Technical Description: This project will establish an integrated platform for ultrafast terahertz-to-mid-infrared quantum optoelectronics based on non-equilibrium two-dimensional van der Waals materials coupled to inverse-designed electromagnetic structures. The research will combine three device thrusts. First, monolayer transition-metal dichalcogenides will be integrated with dual-resonant antennas to enable intra-exciton infrared sensing, in which a mid-infrared field modifies an excitonic optical transition that can be read out with picosecond time resolution. Second, bilayer graphene devices with dynamically driven vertical electric fields will be used to create time-dependent homojunctions for terahertz rectification and frequency doubling. Third, moiré flatband systems will be coupled to tailored terahertz structures to explore dynamic localization, Bloch oscillations, and tunable terahertz emission or amplification. A central technical objective is the co-design of the quantum material, electromagnetic environment, and readout architecture. The project will develop inverse-designed antennas, resonators, couplers, and waveguides that provide strong local field enhancement, controlled mode profiles, and compatibility with realistic gating, biasing, packaging, and nanofabrication constraints. Device performance will be evaluated using ultrafast optical and terahertz spectroscopy, on-chip terahertz measurements, electrical transport, and near-field microwave microscopy. The expected contributions include new physical understanding of driven low-dimensional quantum materials; new computational methods for free-form inverse design of resonant terahertz/infrared electromagnetic structures; and prototype devices for ultrafast sensing, signal conversion, and terahertz generation with a path toward scalable arrays. 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.