Condensation dynamics in a two-dimensional photonic crystal waveguide

TL;DR

This paper demonstrates engineered multimode exciton-polariton condensation in a two-dimensional photonic crystal waveguide, revealing complex dynamical interactions and providing insights for precise control of condensate formation.

Contribution

It introduces a method to engineer and study multimode condensation and mode interactions in a 2D nanostructure with tailored band-structure.

Findings

Multiple condensates form at high-momenta and the $ ext{Gamma}$-point.

Condensates appear non-simultaneously with complex gain and relaxation dynamics.

Full characterization of static and dynamic properties of the condensates.

Abstract

Exciton-polariton condensation occurs at the extrema of the underlying dispersion where the density of states diverges and carriers can naturally accumulate. The existence of multiple such points leads to coupling and competition between the associated modes and dynamical redistribution of the carriers in the dispersion. Here, we directly engineer the above situation via subwavelength periodic patterning of a two-dimensional nanostructure. This leads to multimode condensation into a pair of symmetric condensates that form at high-momenta, accidental-coupling points, and a high-symmetry $\Gamma$-point with a bound-in-the-continuum (BiC) state. The dynamical behaviour of the system reveals the non-simultaneous appearance of these condensates and the interplay of non-trivial gain and relaxation mechanisms. We fully characterise the quasi-static and dynamical regime of this artificial crystal and the properties of the different condensates. This understanding is necessary when band-structure engineering techniques are used to achieve precise control of condensate formation with given energy and momentum.