Nonlinear Quantum Tunneling Effects in Nanoplasmonic Environments: Two-Photon Absorption and Harmonic Generation
Journal of the Optical Society of America B
We use a quantum mechanical approach to derive a set of linear and nonlinear quantum conductivity coefficients for metal–insulator–metal structures with nanometer sized gaps. The immediate proximity of metallic objects generates a tunneling AC current density that endows the gap region with additional linear and nonlinear coefficients that in turn trigger linear and nonlinear absorption, and second- and third-harmonic generation. For example, a vacuum gap approximately 0.8 nm thick displays an effective |𝜒(2)|∼0.1 pm/V for adjacent objects composed of dissimilar metals and an effective |𝜒(3)|∼10−20 m2/V2 for either similar or dissimilar metals, increasing exponentially for smaller gaps. Field localization inside the gap ensures that harmonic generation arising from the gap region overwhelms intrinsic metal second- and third-order nonlinearities.
Copyright © 2014, Optical Society of America
Optical Society of America
Haus, Joseph W.; de Ceglia, Domenico; Vincenti, Maria Antonietta; and Scalora, Michael, "Nonlinear Quantum Tunneling Effects in Nanoplasmonic Environments: Two-Photon Absorption and Harmonic Generation" (2014). Electrical and Computer Engineering Faculty Publications. 273.