Second harmonic generation from an ITO nanolayer: experiment versus theory

Abstract

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Electrodynamics of conductive oxides: Intensity-dependent anisotropy, reconstruction of the effective dielectric constant, and harmonic generation

“…Differing explanations have been provided regarding the source of third-order phenomena [3,4], and practically no good insight into second-order, surface, and magnetic phenomena outside of the context found in Refs. [1] and [5]. In Ref.…”

“…In a recent paper [1] experimental and theoretical results on second and third-harmonic generation (SHG and THG) were reported near the ENZ condition of an ITO nanolayer, which manifested itself near 1240 nm. The pulse propagation model that was used comprised a hydrodynamic description of the material equations that takes into account free and bound charges, nonlocal effects, a time-dependent freeelectron plasma frequency, surface, magnetic, and convective second and third-order nonlinearities, as well as the inclusion of linear and nonlinear contributions of the background medium to the dielectric constant.…”

“…The local dielectric constant of any material may be expressed as a superposition of Lorentz and Drude oscillators, which in the simplest case of two polarization species (one free and one bound electron contribution, as in the case of ITO [1]) may be written as follows:…”

“…If the free-electron effective mass changes approximately linearly with temperature, as shown below using the two-temperature model, the equations of motion are reproduced from Ref. [1], and may be written as follows:…”

“…where˜ is a constant of proportionality, follows from the expansion of the effective mass as a function of temperature and absorption [1,8] (as the summation index indicates, looking ahead to our results our parameter choices demand we retain hot electron nonlinearities up to seventh order);…”