title: Selectively tunable optical Stark effect of anisotropic excitons in atomically thin ReS2.
abstract: The optical Stark effect is a coherent light-matter interaction describing the modification of quantum states by non-resonant light illumination in atoms, solids and nanostructures. Researchers have strived to utilize this effect to control exciton states, aiming to realize ultra-high-speed optical switches and modulators. However, most studies have focused on the optical Stark effect of only the lowest exciton state due to lack of energy selectivity, resulting in low degree-of-freedom devices. Here, by applying a linearly polarized laser pulse to few-layer ReS2, where reduced symmetry leads to strong in-plane anisotropy of excitons, we control the optical Stark shift of two energetically separated exciton states. Especially, we selectively tune the Stark effect of an individual state with varying light polarization. This is possible because each state has a completely distinct dependence on light polarization due to different excitonic transition dipole moments. Our finding provides a methodology for energy-selective control of exciton states.
authors.affiliation: School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
authors.forename: Sangwan
authors.initials: S
authors.lastname: Sim
authors.affiliation: School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
authors.forename: Doeon
authors.initials: D
authors.lastname: Lee
authors.affiliation: School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
authors.forename: Minji
authors.initials: M
authors.lastname: Noh
authors.affiliation: School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
authors.forename: Soonyoung
authors.initials: S
authors.lastname: Cha
authors.affiliation: School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
authors.forename: Chan Ho
authors.initials: CH
authors.lastname: Soh
authors.affiliation: Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang 790-784, Korea.|Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang 790-784, Korea.
authors.forename: Ji Ho
authors.initials: JH
authors.lastname: Sung
authors.affiliation: Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang 790-784, Korea.|Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang 790-784, Korea.|Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-Ro, Pohang 790-784, Korea.
authors.forename: Moon-Ho
authors.initials: MH
authors.lastname: Jo
authors.affiliation: School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
authors.forename: Hyunyong
authors.initials: H
authors.lastname: Choi