School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea.
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.
Nat Commun. 2016 Nov 18;7:13569. doi: 10.1038/ncomms13569.
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 ReS, 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.
光斯达克效应是一种相干光物质相互作用，描述了在原子、固体和纳米结构中，非共振光照明对量子态的修饰。研究人员一直致力于利用这种效应来控制激子态，旨在实现超高速光开关和调制器。然而，由于缺乏能量选择性，大多数研究都集中在最低激子态的光斯达克效应上，导致自由度低的器件。在这里，通过在少层 ReS 上施加线性偏振激光脉冲，由于对称性降低导致激子的面内各向异性增强，我们控制了两个能量分离的激子态的光斯达克位移。特别是，我们可以通过改变光的偏振选择性地调节单个态的斯达克效应。这是可能的，因为由于不同的激子跃迁偶极矩，每个态对光偏振的依赖完全不同。我们的发现为选择性地控制激子态提供了一种方法。
