Abstract
Coherent interaction with off-resonance light can be used to shift the energy levels of atoms, molecules, and solids. The dominant effect is the optical Stark shift, but there is an additional contribution from the so-called Bloch-Siegert shift that has eluded direct and exclusive observation so far, particularly in solids. We observe an exceptionally large Bloch-Siegert shift in monolayer WS2 under infrared optical driving [1]. By controlling the light helicity, we can confine the Bloch-Siegert shift to occur only at one valley and the optical Stark shift at the other valley, because the two effects are found to obey opposite selection rules at different valleys. Such a large and valley-exclusive Bloch-Siegert shift allows for enhanced control over the valleytronic properties of two-dimensional materials.
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Sie, E.J. (2018). Large, Valley-Exclusive Bloch-Siegert Shift in Monolayer WS2 . In: Coherent Light-Matter Interactions in Monolayer Transition-Metal Dichalcogenides. Springer Theses. Springer, Cham. https://doi.org/10.1007/978-3-319-69554-9_6
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DOI: https://doi.org/10.1007/978-3-319-69554-9_6
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