Shah, Raman A.Scherer, Norbert F.Pelton, MatthewGray, Stephen K.2023-08-112023-08-112013-08-12Shah, Raman A., Norbert F. Scherer, Matthew Pelton, and Stephen K. Gray. “Ultrafast Reversal of a Fano Resonance in a Plasmon-Exciton System.” Physical Review B 88, no. 7 (August 12, 2013): 075411. https://doi.org/10.1103/PhysRevB.88.075411.https://doi.org/10.1103/PhysRevB.88.075411http://hdl.handle.net/11603/29189When a two-level quantum dot and a plasmonic metal nanoantenna are resonantly coupled by the electromagnetic near-field, the system can exhibit a Fano resonance, resulting in a transparency dip in the optical spectrum of the coupled system. We calculate the nonlinear response of such a system, for illumination both by continuous-wave and ultrafast pulsed lasers, using both a cavity quantum electrodynamics and a semiclassical coupled-oscillator model. For the experimentally relevant case of thermal broadening of the quantum-dot transition (to meV values consistent with ∼100 K), we predict that femtosecond pulsed illumination can lead to a reversal of the Fano resonance, with the induced transparency changing into a superscattering spike in the spectrum. This ultrafast reversal is due to a transient change in the phase relationship between the dipoles of the plasmon and exciton. It thus represents a new approach to dynamically control the collective optical properties and coherence of coupled nanoparticle systems.7 pagesen-USThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.Public Domain Mark 1.0http://creativecommons.org/publicdomain/mark/1.0/Text