Valley-selective optical Stark effect probed by Kerr rotation
| Autor: | LaMountain, Trevor, Bergeron, Hadallia, Balla, Itamar, Stanev, Teodor K., Hersam, Mark C., Stern, Nathaniel P. |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 97, 045307 (2018) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.97.045307 |
| Popis: | The ability to monitor and control distinct states is at the heart of emerging quantum technologies. The valley pseudospin in transition metal dichalcogenide (TMDC) monolayers is a promising degree of freedom for such control, with the optical Stark effect allowing for valley-selective manipulation of energy levels in WS$_2$ and WSe$_2$ using ultrafast optical pulses. Despite these advances, understanding of valley-sensitive optical Stark shifts in TMDCs has been limited by reflectance-based detection methods where the signal is small and prone to background effects. More sensitive polarization-based spectroscopy is required to better probe ultrafast Stark shifts for all-optical manipulation of valley energy levels. Here, we show time-resolved Kerr rotation to be a more sensitive probe of the valley-selective optical Stark effect in monolayer TMDCs. Compared to the established time-resolved reflectance methods, Kerr rotation is less sensitive to background effects. Kerr rotation provides a five-fold improvement in the signal-to-noise ratio of the Stark effect optical signal and a more precise estimate of the energy shift. This increased sensitivity allows for observation of an optical Stark shift in monolayer MoS$_2$ that exhibits both valley- and energy-selectivity, demonstrating the promise of this method for investigating this effect in other layered materials and heterostructures. Comment: 9 pages, 4 figures, supplementary information |
| Databáze: | arXiv |
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