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Natural materials exhibit only a small part of electromagnetic properties which are available in theory. Researchers have made great efforts to explore new materials that are having some specific desired properties. Electromagnetic metamaterials are artificially engineered materials that are designed to interact and control electromagnetic waves at the beginning of the new era. "Meta" in Greek means "beyond", or "higher", "alerted", or "changed". That says, metamaterials are not found in nature. However, they are composed of natural materials. The designers' role is to engineer the composite "atoms" of the metamaterials from natural materials with different shapes or structures. In most cases, metamaterials are composed of sub-wavelength, periodic structures. The goal of many metamaterial simulations is to design and measure the effective material properties of these devices. The operation frequency range can be at RF, microwave, terahertz (THz) and optics.
Photonic metamaterials are periodic optical nanostructures often composed of metallic elements on a dielectric or semiconducting substrate, where the period is shorter than the wavelength of light. They are of large scientific interest as the dielectric response of those materials can be engineered through semiconductor manufacturing to yield interesting physical phenomena at optical wavelengths.
Effects of interest include realizing synthetic optical structures with an effective negative index of refraction, resulting in so-called negative refraction. Negative refraction can be used to realize superlenses which offer enhanced spatial resolution beyond that available via diffraction-limited focusing. Photonic metamaterials can be used to assess split-ring resonators and optical antennas that can be designed to efficiently capture and emit optical radiation.
FDTD Solutions can be used to study sub-wavelength periodic and highly-diffractive optical metamaterial elements and the interesting optical characteristics they exhibit. One can directly measure various quantities of interest, including:
•Field enhancement at different parts of the structures
•Transmission and reflection spectrum
•Scattering and absorption cross sections
•Chirality and circular dichroism
The effective material properties are also a typical quantity of interest and can be calculated with some post-processing of the simulation results. This includes:
•Effective material properties such as the refractive index, impedance permittivity and permeability
In addition, a combination of optical solvers and electrical solvers can be used to characterize active metamaterials. For example, DEVICE can be used to simulate the effect of bias-induced carrier density variations on the refractive index of the metamaterial, and FDTD Solutions can be used to calculate the corresponding optical response.
•FDTD Solutions can easily calculate the power reflection, power transmission, field enhancements, resonant frequencies and associated quality factors, and s-parameters for metamaterials
•Flexible post-processing allows for the extraction of bulk/effective material properties like effective refractive index including the negative index response of metamaterials, effective permittivity and permeability, circular dichroism, scattering and absorption cross sections
•Lumerical’s conformal mesh technology can provide sub-mesh cell accuracy of common materials used in metamaterials, including perfect electrical conductors (PECs), metals, and other dispersive materials
•Multi-coefficient materials (MCMs) can accurately model dispersive materials across wide wavelength ranges
•Simulate metamaterial microbolometers with FDTD Solutions and the heat transport solver in DEVICE.
•Simulate active metamaterials with FDTD Solutions and the charge transport solver in DEVICE.
•Built-in parameter sweep and optimization algorithms make it easy to analyze and optimize parameterized designs