Second-harmonic generation in plasmonic waveguides with nonlocal response and electron spill-out

Abstract

Plasmonic waveguides provide an integrated platform to develop efficient nanoscale ultrafast photonic devices. Theoretical models that describe nonlinear optical phenomena in plasmonic waveguides, usually, only incorporate bulk nonlinearities, while nonlinearities that arise from metallic constituents remained unexplored. In this work, we present a method that enables a generalized treatment of the nonlinearities present in plasmonic waveguides and use it to calculate secondharmonic generation from free electrons through a hydrodynamic nonlocal description. As a general application of our method we also consider nonlinearities arising from the quantum hydrodynamic theory with electron spill-out. Our results may find applicability in design and analysis of integrated photonic platforms for nonlinear optics incorporating wide variety of nonlinear materials such as heavily doped semiconductors for mid-infrared applications.

Impact of surface charge depletion on the free electron nonlinear response of heavily doped semiconductors

“…plasmonics, has a central role. Plasmonic nanoantennas have been commonly used as local-field amplifier in hybrid systems to enhance optical nonlinearity from dielectric material placed in their vicinity [1][2][3][4], however, the nonlinear response may also arise directly from the plasmonic material itself, specifically from the dynamics of nonequilibrium FEs [5][6][7][8][9][10][11]. Notoriously, noble metals are the main constituents of plasmonic devices in the visible spectrum.…”