Abstract
Two-dimensional semiconductors provide an ideal platform for exploration of linear exciton and
polariton physics, primarily due to large exciton binding energy and strong light-matter coupling. These
features, however, generically imply reduced exciton-exciton interactions, hindering the realization of
active optical devices such as lasers or parametric oscillators. Here, we show that electrical injection of itinerant electrons into monolayer molybdenum diselenide allows us to overcome this limitation:
dynamical screening of exciton-polaritons by electrons leads to the formation of new quasiparticles
termed polaron-polaritons that exhibit unexpectedly strong interactions as well as optical amplification by Bose-enhanced polaron-electron scattering. To measure the nonlinear optical response, we carry out timeresolved pump-probe measurements and observe polaron-polariton interaction enhancement by a factor of 50 (0.5 μeV μm2) as compared to exciton-polaritons. Concurrently, we measure a spectrally integratedntransmission gain of the probe field of ≳2 stemming from stimulated scattering of polaron-polaritons. We show theoretically that the nonequilibrium nature of optically excited quasiparticles favors a previously unexplored interaction mechanism stemming from a phase-space filling in the screening cloud, which provides an accurate explanation of the strong repulsive interactions observed experimentally. Our findings show that itinerant electron-exciton interactions provide an invaluable tool for electronic manipulation of optical properties, demonstrate a new mechanism for dramatically enhancing polariton-polariton interactions, and pave the way for realization of nonequilibrium polariton condensates. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000410130Publication status
publishedExternal links
Journal / series
Physical Review XVolume
Pages / Article No.
Publisher
American Physical SocietyOrganisational unit
03636 - Imamoglu, Atac / Imamoglu, Atac
Funding
671000 - Interacting polaritons in two-dimensional electron systems (EC)
178909 - Quantum photonics using van der Waals heterostructures (SNF)
Related publications and datasets
Is cited by: https://doi.org/10.3929/ethz-b-000401640
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