Ultrafast valley-selective coherent optical manipulation with excitons in WSe${}_2$ and MoS${}_2$ monolayers

Abstract

Increasing the speed limits of conventional electronics requires innovative approaches to manipulate other quantum properties of electrons besides their charge. An alternative approach utilizes the valley degree of freedom in low-dimensional semiconductors. Here we demonstrate that the valley degeneracy of exciton energies in transition metal dichalcogenide monolayers may be lifted by coherent optical interactions on timescales corresponding to few tens of femtoseconds. The optical Stark and Bloch-Siegert effects generated by strong nonresonant circularly-polarized light induce valley-selective blue shifts of exciton quantum levels by more than 30 meV. We show these phenomena by studying the two most intensive exciton resonances in transiton metal dichalcogenide monolayers and compare the results to a theoretical model, which properly includes the Coulomb interaction and exciton dispersion. These results open the door for ultrafast valleytronics working at multiterahertz frequencies.

6 pages, 3 figures, published in npj 2D Materials and Applications

References in corpus (10)

• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Magnetic Control of Valley Pseudospin in Monolayer WSe2
• Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer WSe2
• Valley susceptibility of an interacting two-dimensional electron system
• Ultrafast Generation of Pseudo-magnetic Field for Valley Excitons in WSe2 Monolayers
• Ultrafast Manipulation of Valley Pseudospin
• Valley Polarization in Si(100) at Zero Magnetic Field
• Large, valley-exclusive Bloch-Siegert shift in monolayer WS2
• Valley-selective optical Stark effect probed by Kerr rotation
• Semiconductor Bloch equation analysis of optical Stark and Bloch-Siegert shifts in monolayers WSe${}_2$ and MoS${}_2$

Cited by in corpus (9)

• Valley Polarization-Electric Dipole Interference and Nonlinear Chiral Selection Rules in Monolayer WSe${}_2$
• Interaction induced AC-Stark shift of exciton-polaron resonances
• High harmonic generation in monolayer MoS2 controlled by resonant and near-resonant pulses on ultrashort time scales
• Exciton migration in two-dimensional materials
• Effects of Floquet Engineering on the Coherent Exciton Dynamics in Monolayer WS${}_2$
• AC-Stark Spectroscopy of Interactions between Moiré Excitons and Polarons
• Real and Reciprocal Space Characterization of the 3-Dimensional Charge Density Wave in Quasi-1-Dimensional CuTe
• Ultrafast room-temperature valley manipulation in silicon and diamond
• Tracking the photoinduced dynamics of a dark excitonic state in single-layer WS${}_2$ via resonant Autler-Townes splitting