Takemura, N.Trebaol, S.Anderson, M. D.Kohnle, V.Leger, Y.Oberli, D. Y.Portella-Oberli, M. T.Deveaud, B.2015-12-022015-12-022015-12-02201510.1103/PhysRevB.92.125415https://infoscience.epfl.ch/handle/20.500.14299/121245WOS:000361037500003We investigate polariton-polariton interactions in a semiconductor microcavity through two-dimensional Fourier transform (2DFT) spectroscopy. We observe, in addition to the lower-lower and the upper-upper polariton self-interactions, a lower-upper cross interaction. This appears as separated peaks in the on-diagonal and off-diagonal parts of 2DFT spectra. Moreover, we elucidate the role of the polariton dispersion through a fine structure in the 2DFT spectrum. Simulations, based on lower-upper polariton basis Gross-Pitaevskii equations including both self-and cross interactions, result in a 2DFT spectra in qualitative agreement with experiments.text::journal::journal article::research article