Polariton simulators

Lead Research Organisation: University of Southampton
Department Name: School of Physics and Astronomy

Abstract

Polaritons are quasiparticles arising from the state of strong coupling between an exciton - another quasiparticle, made from an electron hole pair - with a photon trapped in a microcavity. The high binding energy of Frenkel excitons allows for polariton condensation to occur at room temperature, leading to the possibility for polaritons to be used in optoelectronic devices. The weaker bound Wannier-Mott excitons in inorganic semiconductors require cryogenic temperatures to be excited, but, due to years of investigation, are being made into largely disorder free cavities allowing for the possible study of more exotic phenomena, such as giant vortices, and periodic and non-periodic lattices of condensates - a possible platform for quantum simulators. Both regimes have their clear advantages and disadvantages, but ultimately, it is the study of both that will lead to a deeper understanding of the field. Polariton condensation in the yellow part of the visible spectrum from a planar organic semiconductor microcavity containing the molecular dye BODIPY-Br is shown. The ex-perimental ngerprints of polariton condensation under non-resonant optical excitation are presented , including the non-linear dependence of the emission intensity, linewidth narrowing and wavelength blueshift with increasing excitation density, obtained from single pulse dispersion imaging which allows us to visualise the collapse of the energy distribution upon reaching threshold. Also single pulse interferometry is exploited to measure the long-range coherence of the polariton condensate.
The creation of multiply-quantized vortices is demonstrated. By injecting an odd number of polariton condensates at the vertices of a regular polygon and imposing frustration into the system by controlling the interactions across vertices, stable spatially localised circular energy ows can be formed of non-trivial angular momentum. Multiply-quantized vortices, formed at the centre of a polygon on a non-zero density background, allow for the study of vorticity with large topological charges in super fluids.

Polaritons are quasiparticles arising from the state of strong coupling between a an exciton - another quasiparticle made from an electron hole pair - with a photon trapped in a microcavity. The high binding energy of Frenkel excitons allows for polariton and photon lasing to occur at room temperature, making them an ideal candidate for optoelectronic applications. We observe polariton lasing in the yellow part of the visible spectrum from a planar organic semiconductor microcavity containing the molecular dye BODIPY-Br. We present experimental fingerprints of polariton condensation under non-resonant optical excitation, including the non-linear dependence of the emission intensity, linewidth narrowing and wavelength blueshift with increasing excitation density, obtained from single pulse dispersion imaging which allows us to visualise the collapse of the energy distribution upon reaching threshold. We also present single pulse interferometry which allows us to measure the long-range coherence of the polariton condensate.

Publications

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Cookson T (2017) A Yellow Polariton Condensate in a Dye Filled Microcavity in Advanced Optical Materials

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509747/1 01/10/2016 30/09/2021
1753551 Studentship EP/N509747/1 06/06/2016 05/12/2019 Tamsin Cookson
 
Description We have discovered a new class of materials of organic semiconductor microcavities which are able to undergo room temperature polariton condensation, namely, those of molecular dyes suspended in a polymer matrix. This could provide a new platform for the polariton simulator to be performed at room temperature.
Exploitation Route We need to test more dyes and find a more stable candidate for the polariton simulator research.
Sectors Other