CAREER: Coherences and Nonlinear Interactions in Molecular Infrared Polaritons

University Of California-San Diego, La Jolla CA

Investigators

Abstract

Nontechnical Description: Interactions between material at the molecular scale and light can produce a new type of material particle called a polariton. Polaritons have unique properties that make them useful in a broad array of societally relevant applications, including medicine, chemical sensing, and homeland security, to name just a few. While the properties and applications of polaritons resulting from molecule-light interactions for some wavelengths of light have been investigated, relatively less is known about polaritons associated with light at wavelengths in the mid-infrared part of the electromagnetic spectrum. This project uses ultrafast lasers to investigate the fundamental properties of polaritons in the mid-infrared regime, and aims to understand and control interactions among polaritons. The results of this fundamental research are expected to contribute to the eventual development of new technological capabilities in chemical sensing, materials development, and visualization in the dark. Central elements of the education project include development of an online course in photonic materials research aimed at first- and second-year undergraduate students. The course is designed to help overcome many students' fears about math- and science-heavy topics, and to attract a more diverse group of students to the field of materials research. In addition, this project establishes a pipeline for engaging underrepresented minority students in summer research activities at UC San Diego, through collaboration with a faculty member at a historically black college and university (HBCU). Technical Description: Polaritons are hybrid particles resulting from strong coupling between photon and material excitations. The scientific aim of this project is to understand and control the coherences and nonlinear interactions of multiple molecular infrared polaritons, 'on a chip'. The outcome would enable mid-infrared photonic devices, such as mid-infrared optical modulators, waveguides, and lasers, that are crucial for realizing lab-on-chip mid-infrared chemical sensing for the medical and material industries. Polariton research has provided novel photonic applications in the visible and THz regimes, but not in the mid-infrared regime. Yet, mid-infrared polariton photonic devices are critical in developing lab-on-chip chemical sensing. Fundamental knowledge, such as coherent lifetime, spatial coherences, and nonlinear interactions of mid-infrared polaritons remains unclear, which prevents mid-infrared polariton photonic application developments. To advance basic knowledge of mid-infrared polaritons, the research team plans to work on two important aspects: (1) Coherence of mid-infrared polaritons is pushed beyond the natural coherence lifetime of molecular vibrations, breaking limits that currently constrain the use of mid-infrared photons for photonic circuitry and molecular sensing. (2) Coherent and coupled multiple distinguishable polaritons 'on a chip' can open the gateway for creating coherent superpositions of multiple coupled quantum states for multi-color photonic devices. In addition, the novel ultrafast mid-infrared spectroscopic imaging to be developed can be extended into other mid-infrared photonic studies. 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.