Strong Coupling of Light to Collective Terahertz Vibrations in Organic Materials

TL;DR

This paper demonstrates strong coupling of light to collective Terahertz vibrations in organic materials, revealing coherent dynamics and approaching ultra-strong coupling, expanding the scope of polaritonic chemistry to new material classes.

Contribution

It introduces the first demonstration of strong light coupling to collective intermolecular vibrations in the Terahertz range in organic materials.

Findings

Achieved a Rabi splitting of 68 GHz

Observed coherent Rabi oscillations

Approached the ultra-strong coupling regime

Abstract

Several years ago, it was shown that strong coupling between an electronic transition in organic molecules and a resonant photonic structure can modify the electronic landscape of the molecules and affect their chemical behavior. Since then, this new concept has evolved into a new field known as polaritonic chemistry, which employs strong coupling as a new tool for controlling material properties and molecular chemistry. An important ingredient in the progress of this field was the recent demonstration of strong coupling of molecular vibrations to mid-infrared resonators, which enabled the modification of chemical processes occurring at the electronic ground-state of materials. Here we demonstrate for the first time strong coupling with collective, intermolecular vibrations occurring in organic materials in the Terahertz frequency region. Using a tunable, open-cavity geometry, we measure the temporal evolution and observe coherent Rabi oscillations, corresponding to a splitting of 68 GHz and approaching the ultra-strong coupling regime. These results take strong light-matter coupling into a new class of materials, including polymers, proteins and other organic materials, in which collective, spatially extended degrees of freedom participate in the dynamics.