Authors: D. G. Suárez-Forero, F. Riminucci, V. Ardizzone, N. Karpowicz, E. Maggiolini, G. Macorini, G. Lerario, F. Todisco, M. De Giorgi, L. Dominici, D. Ballarini, G. Gigli, A. S. Lanotte, K. West, K. Baldwin, L. Pfeiffer, and D. Sanvitto

Physical Review Letters, Vol. 126, Iss. 13 — 2 April 2021, 137401
DOI:  https://doi.org/10.1103/PhysRevLett.126.137401

Abstract: Exciton-polaritons are hybrid light-matter excitations arising from the nonperturbative coupling of a photonic mode and an excitonic resonance. Behaving as interacting photons, they show optical third-order nonlinearities providing effects such as optical parametric oscillation or amplification. It has been suggested that polariton-polariton interactions can be greatly enhanced by inducing aligned electric dipoles in their excitonic part. However, direct evidence of a true particle-particle interaction, such as superfluidity or parametric scattering, is still missing. In this Letter, we demonstrate that dipolar interactions can be used to enhance parametric effects such as self-phase modulation in waveguide polaritons. By quantifying these optical nonlinearities, we provide a reliable experimental measurement of the direct dipolar enhancement of polariton-polariton interactions.