METAMATERIALS

• What is a metamaterial ?• A metamaterial is a macroscopic/nano

composite of periodic or non-periodic structure, whose function is due to both the artificial cellular architecture and chemical composition. These materials exhibit some properties, that are not usually shown by the naturally occurring materials.

Uses of metamaterials

• In sensor technology(sensor metamaterials)• In designer dispersion (EIT, slow light)• In amplification(amplification metamaterials)• In quantum mechanics(quantum metamaterials)• High low epsilon metamaterials• Switchable metamaterials• Non-linear metamaterials• In transformation optics

SOLAR CELL APPLICATION

• Photonic meta-material is used in multi band solar cell.• In designing high efficiency solar cell (composite

metamaterial)• light trapping applications

Schematic diagram of light trapping

Photonic band gap

• Photonic crystals are composed of periodic dielectric, metallodielectric or even superconductor microstructures or nanostructures that affect the propagation of electromagnetic waves (EM) in the same way as the periodic potential in a semiconductor crystal affects the electron motion by defining allowed and forbidden electronic energy bands. Photonic crystals contain regularly repeating regions of high and low dielectric constant. Photons (behaving as waves) propagate through this structure – or not – depending on their wavelength. Wavelengths that are allowed to travel are known as modes; groups of allowed modes form bands. Disallowed bands

of wavelengths are called photonic band gaps.

Negative refractive index

It happens due to the simultaneous existence of 1 negative permeability 2 Negative permittivity

Negative permittivity and permeability

The resonating wires give the material negative permittivity

The resonating loops give the material Negative permeability

HOW??

• Metamaterials are artificial electromagnetic media structured on a scale much shorter than their operating wavelength. Under this condition they can be considered as homogeneous media whose electromagnetic properties rely mainly on the basic cell rather than periodic effects as it is the case for photonic crystal or more generally electromagnetic band gap material. Their basic cells are generally constituted of resonant inclusions which yield a π phaseshift in the material response above the resonant frequency. As a consequence, their effective permittivity and permeability can be negative either in separate or overlapping frequency bands, a unique and distinct property that is not observed in naturally occurring materials1.

Demonstration

FEM (finite element materials)

• the finite element method (FEM) is a numerical technique for finding approximate solutions to boundary value problems fordifferential equations. It uses variational methods (the calculus of variations) to minimize an error function and produce a stable solution. Analogous to the idea that connecting many tiny straight lines can approximate a larger circle, FEM encompasses all the methods for connecting many simple element equations over many small sub-domains, named finite elements, to approximate a more complex equation over a larger domain.

What meshing does:-

• 1. dividing the domain of the problem into a collection of sub-domains, with each sub-domain is represented by a set of element equations to the original problem, followed by

• 2. systematically recombining all the set of element equations for the final equations for the final calculations.

Reasons and Advantages of meshing:-

• Accurate representation of the complex geometry

• Inclusion of dissimilar properties• Easy representation of the total solution• Capture of local effects• Break complex calculations into smaller parts• More accurate calculations and results

Maxwell’s Eqns

Eqns cont…

• The great unification of two field theory was done by Maxwell much before the discovery of electromagnetic wave.

• It shows the inter dependency of the two waves, and are inter convertable