Abstract
Strong optical nonlinearities play a central role in realizing quantum photonic technologies. Exciton-polaritons, which result from the hybridization of material excitations and cavity photons, are an attractive candidate to realize such nonlinearities. While the interaction between ground state excitons generates a notable optical nonlinearity, the strength of such interactions is generally not sufficient to reach the regime of quantum nonlinear optics. Excited states, however, feature enhanced interactions and therefore hold promise for accessing the quantum domain of single-photon nonlinearities. Here we demonstrate the formation of exciton-polaritons using excited excitonic states in monolayer tungsten diselenide (WSe2) embedded in a microcavity. The realized excited-state polaritons exhibit an enhanced nonlinear response ∼{g}_{{pol}-{pol}}^{2s} sim 46.4pm 13.9,mu {eV}mu {m}^{2} which is ∼4.6 times that for the ground-state exciton. The demonstration of enhanced nonlinear response from excited exciton-polaritons presents the potential of generating strong exciton-polariton interactions, a necessary building block for solid-state quantum photonic technologies.
Highlights
Strong optical nonlinearities play a central role in realizing quantum photonic technologies
Three layers of hexagonal boron nitride encapsulated WSe2 were transferred on top of the distributed Bragg reflector (DBR) followed by spin coating 212 nm Poly (PMMA)
The WS2 monolayer was encapsulated between the hexagonal boron nitride (hBN) layers and the cavity consisted of a similar bottom DBR mirror as used above for the WSe2 cavity
Summary
Strong optical nonlinearities play a central role in realizing quantum photonic technologies. Exciton-polaritons, quasiparticles arising from the strong coupling between cavity photons and excitons in semiconductors, allow for the observation of exotic physical phenomena such as condensation[1,2,3], superfluidity[4], and quantized vortices[5], can be engineered to emulate systems such as atomic lattices for potential applications as quantum simulators[6], as well as for optoelectronic applications such as low energy switches[7], transistors[8], and interferometers[9] This array of rich physical phenomena and the associated applications stem from the half-light half-matter make up of these quasiparticles. The associated interaction strength of 2 s exciton-polaritons is shown to be ∼4.6 times larger than that of the 1 s exciton-polaritons in similar TMD systems, an enhancement that agrees with the scaling of the Bohr radius[37]
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