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Date: Tuesday, January 26, 2016
Time: 11:00 am
Speaker: Igal Brener, Center for Integrated Nanotechnologies (CINT), Sandia-Los Alamos National Laboratories
Title: Active Dielectric and Metallic Metasurfaces: Strong Coupling, Tuning and Nonlinearities
Location: 67-3111 Chemla Room


Metasurfaces (2D arrays of metamaterial resonators) can be designed to exhibit strong electromagnetic resonances that can couple efficiently to emitters and a variety of excitations in semiconductors and their heterostructures. For metallic metasurfaces, past studies of this coupling have included phonons, intersubband transitions and plasmons. This coupling can be exploited for fundamental studies of light matter interaction or for optoelectronic functionality such as light modulation, tunable spectral filtering or optical nonlinearities. For example, record second order nonlinearities can be obtained when metallic metasurfaces are coupled with resonant electronic transitions in semiconductors such as intersubband transitions. Additionally, since the nonlinear unit in this case is a single resonator coupled to the semiconductor heterostructure, additional functionality can be obtained at the second harmonic beam. Using this principle, we have created beam and polarization splitters operating at the second harmonic wavelength. This is new functionality that has no counterpart in conventional nonlinear optical materials.

All-dielectric metasurfaces consist of arrays of dielectric nanoresonators that can also be designed to exhibit strong electric and magnetic resonances. Recently, there has been a flurry of activity in dielectric metasurfaces at optical wavelengths for a variety of purposes such as control of emission, beam shaping and holography, chirality, optical magnetism, etc. Also, fabricating such dielectric metasurfaces from different types of semiconductors can be used to enhance their second and third order nonlinearities by several orders of magnitudes.

In this talk I will present an overview of these metasurfaces, both metallic and dielectric, and different coupling mechanisms that can be used for active tuning and enhancement of optical nonlinearities.