Modeling Nonlocal and Nonlinear Response Phenomena of Plasmonic and Biological Systems

Abstract

In this work, we first examine nonlocal behavior in plasmonic systems and develop or expand upon models that enable calculation of higher-order, nonlocal responses for systems with novel geometries. The effects of nonlocality, i.e., spatial dispersion, are prominent in nanostuctures with small feature sizes, and accurate calculations of the nonlocal response of nanostructures are increasingly important for the study of novel physics at the nanoscale. Next, we consider a specific biological system, double-stranded DNA, and investigate the nonlocal and nonlinear model that describes its dynamics. We consider the regime of strong driving with THz radiation and study the parameter-space where molecular damage occurs, motivated by the prospect of using selective damage for potential novel therapies. In a related study, we also consider the possibility of generating THz radiation through the nonlinear, difference-frequency response of a plasmonic system. Plasmonic difference-frequency generation could enable deep penetration of THz signals into the body and, therefore, these projects are intimately connected. Ultimately, these two regimes of behavior, nonlocality and nonlinearity, represent rich areas for applicable research.