# 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.

## Key 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.

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Source: https://tomesphere.com/paper/1901.02487