@article{ffd0498008ad4a459971fe082b59f0ae,
title = "Valley-selective optical Stark effect probed by Kerr rotation",
abstract = "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.",
author = "Trevor Lamountain and Hadallia Bergeron and Itamar Balla and Stanev, {Teodor K.} and Hersam, {Mark C.} and Stern, {Nathaniel P.}",
note = "Funding Information: This work was primarily supported by the Office of Naval Research under Grant No. N00014-16-1-3055 (valley manipulation). Sample preparation, characterization, and spectroscopy were supported by the National Science Foundations MRSEC program (DMR-1720139) at the Materials Research Center of Northwestern University. Chemical vapor deposition of monolayer was supported by the National Institute of Standards and Technology (NIST CHiMaD 70NANB14H012). This work utilized Northwestern University Micro/Nano Fabrication Facility (NUFAB), which is partially supported by Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the Materials Research Science and Engineering Center (NSF DMR-1720139), the State of Illinois, and Northwestern University. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship. H.B. acknowledges support from the NSERC Postgraduate Scholarship-Doctoral Program. N.P.S. gratefully acknowledges support as an Alfred P. Sloan Research Fellow. Funding Information: This work was primarily supported by the Office of Naval Research under Grant No. N00014-16-1-3055 (valley manipulation). Sample preparation, characterization, and spectroscopy were supported by the National Science Foundations MRSEC program (DMR-1720139) at the Materials Research Center of Northwestern University. Chemical vapor deposition of monolayer MoS 2 was supported by the National Institute of Standards and Technology (NIST CHiMaD 70NANB14H012). This work utilized Northwestern University Micro/Nano Fabrication Facility (NUFAB), which is partially supported by Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the Materials Research Science and Engineering Center (NSF DMR-1720139), the State of Illinois, and Northwestern University. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship. H.B. acknowledges support from the NSERC Postgraduate Scholarship-Doctoral Program. N.P.S. gratefully acknowledges support as an Alfred P. Sloan Research Fellow. ",
year = "2018",
month = jan,
day = "25",
doi = "10.1103/PhysRevB.97.045307",
language = "English",
volume = "97",
journal = "Physical Review B",
issn = "2469-9950",
publisher = "American Physical Society",
number = "4",
}