Title: TUNABLE TERAHERTZ SOURCES BASED ON GRAPHENE PLASMONIC OSCILLATORS
Name: Yuyu Li
Date: December 10, 2019
Location: PHO 536
Advisor: Roberto Paiella, ECE
Chair: Anna Swan, ECE
Committee: Sahar Sharifzadeh, ECE; Xi Ling, Chemistry
The development of optoelectronic devices operating in the terahertz spectral range, lying at the boundary between the microwave and infrared regions, has been a long-standing challenge. Current solutions such as THz quantum cascade lasers (QCLs) and photoconductive antennas all suffer from important limitations that hinder their practical use. A novel compact THz source capable of room-temperature operation is therefore highly desirable. Traditional approaches and materials cannot fulfill this goal. Recently, graphene has emerged as a promising new materials system for basic studies and device applications in THz optoelectronics, with several key functionalities including photodetection and optical modulation already demonstrated.
Here, I propose a new approach for THz light emission based on the reciprocal process of optical plasmonic excitation in graphene. By injecting hot carriers into suitably shaped graphene nanostructures, localized plasmonic oscillations can be excited and radiate into free space. With the proper design, a compact THz source working at room-temperature with reasonable efficiency can be achieved. Initial experimental results, illustrating the promise of this approach, have already been generated in my work so far. This research will also provide a new path for the study of plasmonic and hot-carrier phenomena in graphene.