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Over the last decade, there has been tremendous success in developing optical metasurfaces with desired properties using innovative nanopatterned metal-dielectric composite films. However, major problems towards the mass production and use of these metafilms include expensive and poorly-scalable nanofabrication along with ohmic losses in their nanostructured metallic elements. More advanced approaches in this area include designs providing for (i) electrical or all-optical control of the metasurface responses to get their switchable or multi-functional performance, and (ii) ability to compensate loss and achieve lasing by adding gain inclusions. In all these cases, modeling only light propagation in nanostructured and optically dispersive media is not sufficient to fully understand, control and optimize the performance of a given metadevice. Instead, 3D full-wave time-domain electrodynamics should be coupled to additional nanoscale equations describing complex light-matter interactions at ab-initio level, thus providing a designer with an advanced multiphysics and possibly multiscale numerical modeling framework.
Here, we present our multiphysics time-domain modeling framework for tunable and active photonics. First, we start with reviewing our efficient time-domain approach to modeling tunable graphene-based devices, where the integral multi-parametric surface conductivity is reformulated in time domain with physically interpretable and fast-to-compute integration-free terms. Then, we discuss a multiphysics approach to model optically tunable materials, where classical electrodynamics is coupled to non-equilibrium thermodynamics of electrons and lattice ions. Finally, we present our models of non-linear media built on carrier kinetics, including nanolasers and loss-compensated plasmonic metafilms, as well as metadevices with absorption saturation and reversed absorption saturation effects.
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