Microcavity design for low threshold polariton condensation with ultrashort optical pulse excitation

TL;DR

This paper introduces a novel microcavity design with a shifted photonic stop-band that significantly enhances polariton condensation efficiency under ultrashort optical pulse excitation, demonstrated through theory and experiments.

Contribution

The study presents a new microcavity structure that improves polariton injection efficiency and reduces condensation threshold using broad femtosecond pulses, validated both theoretically and experimentally.

Findings

Microcavity design enhances injection efficiency by 4 times at 740 nm.

Efficiency improvement reaches 270 times at 750 nm.

Lower threshold for polariton condensation compared to conventional microcavities.

Abstract

We present a microcavity structure with a shifted photonic stop-band to enable efficient non-resonant injection of a polariton condensate with spectrally broad femtosecond pulses. The concept is demonstrated theoretically and confirmed experimentally for a planar GaAs/AlGaAs multilayer heterostructure pumped with ultrashort near-infrared pulses while photoluminescence is collected to monitor the optically injected polariton density. As the excitation wavelength is scanned, a regime of polariton condensation can be reached in our structure at a consistently lower fluence threshold than in a state-of-the-art conventional microcavity. Our microcavity design improves the polariton injection efficiency by a factor of 4, as compared to a conventional microcavity design, when broad excitation pulses are centered at a wavelength of 740 nm. Most remarkably, this improvement factor reaches 270 when the excitation wavelength is centered at 750 nm.