Furthermore, the hysteresis-type dependence of the magnetic permeability on the field intensity allows changing the material from left to right-handed and back.
The unit cells are materials that are ordered in geometric arrangements with dimensions that are fractions of the wavelength of the radiated electromagnetic wave.
[10][11] By having the freedom to alter effects by adjusting the configurations and sizes of the unit cells, control over permittivity and magnetic permeability can be achieved.
[15] Since the repeating, scattering, resonant elements, which make up the engineered material are much smaller than the frequency of propagating light, metamaterials can now, also, be described in terms of macroscopic quantities.
[15][16] Of particular interest regarding nonlinear metamaterials, is the artificially induced macroscopic property known as negative refractive index.
[1][15][16][17][18][19] In NIMs, nonlinear phenomena such as second-harmonic generation and parametric amplification can take on highly unusual characteristics.
[20] Previous studies of left-handed or negative index metamaterials were focused on the linear properties of the medium during wave propagation.
In such cases, the view was that magnetic permeability and material permittivity are each not dependent on the intensity of the electromagnetic field.
[2][17] A composite structure consisting of a square lattice of the periodic arrays of conducting wires and split-ring resonators, produces an enhanced magnetic response.
[2][17] Variable capacitance diodes are incorporated into the split-ring cell producing a dynamic tunable system.
[19] Fabrication and experimental studies of the properties of the first nonlinear tunable metamaterial were operating at microwave frequencies.
[15] The fabrication and experimental studies of the properties of thenonlinear tunable magnetic metamaterial were operating at microwave frequencies.
[21] A novel class of nonlinear metamaterials has been proposed and engineered to demonstrate a resonant electric response within microwave frequency ranges.
This design enables the manipulation of the frequency of the electric mode stop band by modulating the incident power levels.
This is drastically modified when nonlinearity of the magnetic response is taken into account, creating a controllable shielding effect in LHMs, accompanied by a parametric reflection.
A metamaterial comprising a large number of such metadimers can be utilized as an actively tunable medium at optical wavelengths.