Affiliation:
1. U.S. Naval Research Laboratory
2. University of Oklahoma
Abstract
Strong coupling of mid-infrared (mid-IR) vibrational transitions to optical cavities provides a means to modify and control a material’s chemical reactivity and offers a foundation for novel chemical detection technology. Currently, the relatively large volumes of the mid-IR photonic cavities and weak oscillator strengths of vibrational transitions restrict vibrational strong coupling (VSC) studies and devices to large ensembles of molecules, thus representing a potential limitation of this nascent field. Here, we experimentally and theoretically investigate the mid-IR optical properties of 3D-printed multimode metal–insulator–metal (MIM) plasmonic nanoscale cavities for enabling strong light–matter interactions at a deep subwavelength regime. We observe strong vibration-plasmon coupling between the two dipolar modes of the L-shaped cavity and the carbonyl stretch vibrational transition of the polymer dielectric. The cavity mode volume is half the size of a typical square-shaped MIM geometry, thus enabling a reduction in the number of vibrational oscillators to achieve strong coupling. The resulting three polariton modes are well described by a fully coupled multimode oscillator model where all coupling potentials are non-zero. The 3D printing technique of the cavities is a highly accessible and versatile means of printing arbitrarily shaped submicron-sized mid-IR plasmonic cavities capable of producing strong light–matter interactions for a variety of photonic or photochemical applications. Specifically, similar MIM structures fabricated with nanoscopic voids within the insulator region could constitute a promising microfluidic plasmonic cavity device platform for applications in chemical sensing or photochemistry.
Funder
Office of Naval Research
U.S. Naval Research Laboratory Base Programs
Subject
Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials