Coherent Contributions to Population Dynamics in a Semiconductor Microcavity

TL;DR

This paper uses multidimensional coherent spectroscopy to distinguish between coherent and incoherent population dynamics in a semiconductor microcavity, revealing complex interactions and decay behaviors in exciton-polariton systems.

Contribution

It introduces a method to separate coherent and incoherent contributions in population dynamics using MDCS and Bloch equation simulations in a semiconductor microcavity.

Findings

Fast decay and oscillations from coherent response observed.

Longer mutual-interaction features do not follow simple decay models.

Simulations qualitatively replicate experimental results and separate interaction contributions.

Abstract

Multidimensional coherent spectroscopy (MDCS) is used to separate coherent and incoherent many-body contributions to the population-time dynamics in a GaAs-based semiconductor microcavity encapsulating a single InGaAs quantum well. In a three-pulse four-wave-mixing scheme, the second delay time is the population time that in MDCS probes excited-state coherences and population dynamics. Nonlinear optical interactions can mix these contributions, which are isolated here for the lower- and upper-exciton-polariton through the self- and mutual-interaction features. Results show fast decays and oscillations arising from the coherent response, including a broad stripe along the absorption energy axis, and longer time mutual-interaction features that do not obey a simple population decay model. These results are qualitatively replicated by Bloch equation simulations for the 1s exciton strongly coupled to the intracavity field. The simulations allow for separation of coherent and incoherent Pauli-blocking and Coulomb interaction terms within the chi^(3)-limit, and direct comparison of each feature in one-quantum rephasing and zero-quantum spectra.