Transient spectroscopic studies on the co-dependence of hot-carrier dynamics and active optical response of a 1D plasmonic crystal*

Ultrafast nonlinear optical properties of plasmonic systems highly depend on the dynamics of hot carriers, defined as high energy electrons and holes generated upon the nonradiative decay of plasmon resonances. From a microscopic view, the third-order Kerr-type nonlinearity of an optically excited plasmonic metal follows the characteristic timescales of the formation and relaxation of hot carriers, until the electron-phonon scattering brings excited electrons to an equilibrium condition with the metal lattice. Understanding these characteristic timescales is thus pivotal for efficient design of active plasmonic platforms. Here, we present a comprehensive picture that reveals the interplay of hot-carrier transient dynamics and the optical response of a 1D plasmonic crystal. The sensitivity of lattice resonance modes to the in-plane momentum of impinging light allows the spectral tuning of the resonance wavelength. Therefore, exploring the co-dependence of hot-carrier relaxation dynamics and active linear and nonlinear resonance properties of the devised plasmonic crystal can be explored over a wide spectral range. As prospective applications, we demonstrate the ultrafast control of resonance band separation and coherent control of light attributes through hot-carrier dynamics.