Exciton-polaritons in GaAsbased slab waveguide photonic crystals

TL;DR

This paper demonstrates the creation of tunable band gaps for exciton-polaritons in GaAs-based photonic crystal waveguides, paving the way for topologically nontrivial quantum states.

Contribution

It reports the experimental observation of tunable band gaps for exciton-polaritons in patterned GaAs waveguides, a novel step towards topological polariton states.

Findings

Observed band gaps of about 10 meV in GaAs photonic crystal waveguides.

Tunable light-matter composition of gaps from photonic to excitonic.

Potential for realizing quantum-Hall-like topological states.

Abstract

We report the observation of band gaps for low loss exciton-polaritons propagating outside the light cone in GaAs-based planar waveguides patterned into two-dimensional photonic crystals. By etching square lattice arrays of shallow holes into the uppermost layer of our structure, we open gaps on the order of 10 meV in the photonic mode dispersion, whose size and light-matter composition can be tuned by proximity to the strongly coupled exciton resonance. We demonstrate gaps ranging from almost fully photonic to highly excitonic. Opening a gap in the exciton-dominated part of the polariton spectrum is a promising first step towards the realization of quantum-Hall-like states arising from topologically nontrivial hybridization of excitons and photons.