Hot-Electron Plasmonics for Ultrafast Control of Intensity, Phase, and Polarization of light

The term “hot electron” is often used in the literature to describe electrons in a solid with energies exceeding their thermally-created counterparts at room temperature. In plasmonic structures, the nonradiative dephasing of plasmons generates excited (i.e., athermal) electrons in the conduction band of metals and a subsequent electron thermalization step leads to the equilibration of athermal electrons and the formation of a hot-electron distribution. Exploring the dynamics of such energetic electrons has recently gained a growing attention with the hope for the implementation of active plasmonic platforms. Here, we show that the ultrafast transfer of hot electrons from plasmonic metals to dielectric materials allows for the suppicosecond (< 190 fs) modulation of plasmonic responses. Our findings suggest that the activation of hot-electron transfer pathways lower the impact of electron-photon interactions and instead provide an electron-dominated relaxation mechanism. Through the design of a subradiant, high-Q, and polarization-sensitive plasmonic crystal we demonstrate ultrafast control of phase, polarization, and intensity of light in an all-optical manner.

1. Taghinejad et al, Advanced Materials 30, 17049015-21 (2018)

2. Taghinejad et al, Nano Letters 18, 5544-5551 (2018)