Evidence for Polariton-Mediated Biexciton Transition in Single-Walled Carbon Nanotubes

Abstract

Strong coupling of excitonic resonances with a cavity gives rise to exciton-polaritons which possess a modified energy landscape compared to the uncoupled emitter. However, due to the femtosecond lifetime of the so-called bright polariton states and transient changes of the cavity reflectivity under excitation, it is challenging to directly measure the polariton excited state dynamics. Here, near-infrared pump-probe spectroscopy is used to investigate the ultrafast dynamics of exciton-polaritons based on strongly-coupled (6,5) single-walled carbon nanotubes in metal-clad microcavities. We present a protocol for fitting the reflectivity-associated response of the cavity using genetic algorithm-assisted transfer matrix simulations. With this approach are able to identify an absorptive exciton-polariton feature in the transient transmission data. This feature appears instantaneously under resonant excitation of the upper polariton but is delayed for off-resonant excitation. The observed transition energy and detuning dependence point toward a direct upper polariton to biexciton transition. Our results provide direct evidence for exciton-polariton intrinsic transitions beyond the bright polariton lifetime in strongly-coupled microcavities.

References in corpus (6)

• Enhanced Delayed Fluorescence in Tetracene Crystals by Strong Light-Matter Coupling
• Biexciton stability in carbon nanotubes
• Population of Exciton-Polaritons via Luminescent sp${}^3$ Defects in Single-Walled Carbon Nanotubes
• Femtosecond Photophysics of Molecular Polaritons
• Ultrafast Thermal Modification of Strong Coupling in an Organic Microcavity
• Charge Transfer from Photoexcited Semiconducting Single-Walled Carbon Nanotubes to Wide-Bandgap Wrapping Polymer

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