Coherent light-matter interaction can transiently modulate the quantum states of matter under nonresonant laser excitation. This phenomenon, called the optical Stark effect, is one of the promising candidates for realizing ultrafast optical switches. However, the ultrafast modulations induced by the coherent light-matter interactions usually involve unwanted incoherent responses, significantly reducing the overall operation speed. Here, by using ultrafast pump-probe spectroscopy, we suppress the incoherent response and modulate the coherent-to-incoherent ratio in the two-dimensional semiconductor ReS2. We selectively convert the coherent and incoherent responses of an anisotropic exciton state by solely using photon polarizations, improving the control ratio by 3 orders of magnitude. The efficient modulation was enabled by transient superpositions of differential spectra from two nondegenerate exciton states due to the light polarization dependencies. This work provides a valuable contribution toward realizing ideal ultrafast optical switches.
Bibliographical noteFunding Information:
S.S. was supported by the National Research Foundation of Korea (NRF) through the government of Korea (MSIP) (Grant NRF-2019R1F1A1063457). J.L., M.N., H.B., and H.C. were supported by the NRF through the government of Korea (MSIP) (Grant NRF-2018R1A2A1A05079060, the Creative Materials Discovery Program (Grant 2017M3D1A1040828), Scalable Quantum Computer Technology Platform Center (Grant 2019R1A5A1027055), and the Institute for Basic Science (IBS), Korea under Project Code IBS-R014-G1-2018-A1). D.L. and K.L. were supported from the U.S. National Science Foundation (NSF) under Grant CMMI-1825256. M.-H. J. and S. Ch. were supported by the Institute for Basic Science (IBS), Korea (project code IBS-R014-A1).
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering