Multidimensional Coherent Spectroscopy of a Semiconductor Microcavity

TL;DR

This study employs multidimensional coherent spectroscopy to map and analyze the exciton-polariton interactions and biexciton features in a semiconductor microcavity across various detuning conditions, revealing detailed interaction dynamics.

Contribution

It provides the first detailed mapping of intra- and inter-polariton interactions and biexciton effects in a semiconductor microcavity using 2D coherent spectra.

Findings

Identification of intra-action and interaction features related to polariton branches.

Observation of biexciton features shifted by binding energy.

Detuning-dependent modulation and asymmetry of spectral features.

Abstract

Rephasing and non-rephasing two-dimensional coherent spectra map the anti-crossing associated with normal-mode splitting in a semiconductor microcavity. For a 12-meV detuning range near zero detuning, it is observed that there are two diagonal features related to the intra-action of exciton-polariton branches and two off-diagonal features related to coherent interaction between the polaritons. At negative detuning, the lineshape properties of the diagonal intra-action features are distinguishable and can be associated with cavity-like and exciton-like modes. A biexcitonic companion feature is observed, shifted from the exciton feature by the biexciton binding energy. Closer to zero detuning, all features are enhanced and the diagonal intra-action features become nearly equal in amplitude and linewidth. At positive detuning the exciton- and cavity-like characteristics return to the diagonal intra-action features. Off-diagonal interaction features exhibit asymmetry in their amplitudes throughout the detuning range. The amplitudes are strongly modulated (and invert) at small positive detuning, as the lower polariton branch crosses the bound biexciton energy determined from negative detuning spectra.