Large optical nonlinearity enhancement under electronic strong coupling

TL;DR

This paper demonstrates a two-order magnitude enhancement of nonlinear optical response and ultrafast reaction times by strongly coupling organic molecule excitons with an optical cavity, opening new avenues for nonlinear optics applications.

Contribution

It introduces a method to significantly boost nonlinear optical effects through strong light-matter coupling in a cavity system, with ultrafast response times.

Findings

Two orders of magnitude increase in nonlinear refractive index.

Ultrafast response time of approximately 120 femtoseconds.

Potential for advanced nonlinear optical applications.

Abstract

Nonlinear optical responses provide a powerful way to understand the microscopic interactions between laser fields and matter. They are critical for plenty of applications, such as in lasers, integrated photonic circuits, biosensing and medical tools. However, most materials exhibit weak optical nonlinearities or long response times when they interact with intense optical fields. Here, we strongly couple the exciton of organic molecules to an optical mode of a Fabry-Perot cavity, and achieve an enhancement of the nonlinear complex refractive index by two orders of magnitude compared with that of the uncoupled condition. Moreover, the coupled system shows an ultrafast response of ~120 fs that we extract from optical cross-correlation measurements. The ultrafast and large enhancement of the nonlinar coefficients in this work paves the way for exploring strong coupling effects on various third-order nonlinear optical phenomena and for technological applications.