Departmental Seminar

Nonlinear optical properties of excitons in transition metal dichalcogenide monolayers

Dr Leonid Golub
Ioffe Institute, St Petersburg, Russia

Linear and nonlinear optical properties of transition metal dichalcogenides monolayers are controlled by the Wannier-Mott excitons forming a series of 1s, 2s, 2p, . . . hydrogen-like states. We demonstrate that p- and s-shell excitons are mixed due to the specific D3h point symmetry of the transition metal dichalcogenide monolayers. Hence, both s- and p-shell excitons are active in both single- and two-photon processes providing an efficient mechanism of second harmonic generation. In addition, s-excitons are active in two-photon absorption due mixing with p-excitons in remote bands. The corresponding contributions to the nonlinear susceptibility are calculated [1]. We also study the Auger exciton-exciton annihilation which results in the photoluminescence upconversion.

[1] Intrinsic exciton-state mixing and nonlinear optical properties in transition metal dichalcogenide monolayers, M. M. Glazov, L. E. Golub, G. Wang, X. Marie, T. Amand, and B. Urbaszek, Phys. Rev. B 95, 035311 (2017).

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