Valley-selective optical Stark effect probed by Kerr rotation

作     者：Trevor LaMountain Hadallia Bergeron Itamar Balla Teodor K. Stanev Mark C. Hersam Nathaniel P. Stern 

作者机构：Applied Physics Program Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA Department of Chemistry Northwestern University Evanston Illinois 60208 USA Department of Electrical Engineering and Computer Science Northwestern University Evanston Illinois 60208 USA 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2018年第97卷第4期

页      面：045307-045307页

核心收录：

基　　金：Northwestern University, NU Northwestern University Micro/Nano Fabrication Facility Soft and Hybrid Nanotechnology Experimental Materials Research Science and Engineering Center, Harvard University, MRSEC Natural Sciences and Engineering Research Council of Canada, NSERC Office of Naval Research, ONR, (N00014-16-1-3055) Office of Naval Research, ONR National Science Foundations MRSEC, (DMR-1720139) National Institute of Standards and Technology, NIST, (CHiMaD 70NANB14H012) National Institute of Standards and Technology, NIST National Science Foundation, NSF, (ECCS-1542205) National Science Foundation, NSF 

主　　题：Dielectric properties Excitons Semiconductors Transition metal dichalcogenides Kerr effect Reflectivity 

摘      要：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 WS2 and WSe2 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 fivefold 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 MoS2 that exhibits both valley and energy selectivity, demonstrating the promise of this method for investigating this effect in other layered materials and heterostructures.