GaAs Microcavity Exciton-Polaritons in a Trap

TL;DR

This paper introduces a simple metal-film method to create controllable in-plane potential traps for exciton-polaritons in GaAs microcavities, enabling new possibilities for polariton condensate arrays and lattices.

Contribution

The authors demonstrate a novel, straightforward technique to generate tunable in-plane potentials in microcavities using metal films, with experimental validation and potential for lattice applications.

Findings

Potential amplitude of a few hundreds of ueV at 6-8 K.

Cavity resonance blue-shifted due to reduced effective cavity length.

Electric voltage modifies exciton modes via quantum confined Stark effect.

Abstract

We present a simple method to create an in-plane lateral potential in a semiconductor microcavity using a metal thin-film. Two types of potential are produced: a circular aperture and a one-dimensional (1D) periodic grating pattern. The amplitude of the potential induced by a 24 nm-6 nm Au/Ti film is on the order of a few hundreds of ueV measured at 6 ~ 8 K. Since the metal layer makes the electromagnetic fields to be close to zero at the metal-semiconductor interface, the photon mode is confined more inside of the cavity. As a consequence, the effective cavity length is reduced under the metal film, and the corresponding cavity resonance is blue-shifted. Our experimental results are in a good agreement with theoretical estimates. In addition, by applying a DC electric voltage to the metal film, we are able to modify the quantum well exciton mode due to the quantum confined Stark effect, inducing a ~ 1 meV potential at ~ 20 kV/cm. Our method produces a controllable in-plane spatial trap potential for lower exciton-polaritons (LPs), which can be a building block towards 1D arrays and 2D lattices of LP condensates.