Xiaoheng Chen received his B.S. degree in physical chemistry from the University of Science and Technology of China. Now he is a graduate student at Kaifeng Wu’s group in Dalian Institute of Chemical Physics. His research focuses on ultrafast spectroscopy and quantum dots.
Kaifeng Wu obtained his B.S. degree in materials physics from University of Science and Technology of China (2010) and his PhD degree in physical chemistry from Emory University (2015). After his postdoctoral research at Los Alamos National Laboratory, he moved to Dalian Institute of Chemical Physics, Chinese Academy of Sciences to start his independent research in 2017. His current work focuses on the ultrafast spectroscopy of carrier and spin dynamics in low-dimensional optoelectronic materials, as well as relevant applications in quantum information and energy conversion technologies.
Fig. 1.
(Color online) (a) Valley-dependent optical selection rules for interband transitions in monolayer TMDs. σ+ polarized light couples to the K (red) valley, and σ− polarized light couples to the K’ (blue) valley[4]. (b) Generation of pump pulse pair using TWINS and measuring valley dynamics through TRFR. (c) TRFR experimental results obtained by continuously varying the delay between the pump pulses (t12) and keeping the probe pulse delay (tPR) fixed. (d) Three-level V-type system illustrating valley decoherence and depolarization. (e) Pulse sequence used for the experiments and simulations in panel f and g. (f, g) TRFR data (circles) obtained by scanning the pump–probe delay (tPR), with the delay between the two pulse pairs (t23) set to 59.9 fs (switching, panel f) or to 58.9 fs (amplification, panel g). For both sets of experiments, t12 = t34 = 41.2 fs. Solid lines are simulations. Panels b–g are from ref.[3].
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