METAMATERIALS

Caleb HughesHassan Ismail

Brett McCutchan

ECIV 30311/30/2010

Scope

• What are Metamaterials• How They Work• Types• Applications• Recent Advances

What are Metamaterials?

Engineered (at the atomic level) materials that have unique properties not found in nature due to the arrangement and design of their constituents

NOTE: THE PROPERTIES ARE THAT OF THE ENTIRE ARRANGEMENT AND NOT THE CONSTITUENTS THEMSELVES

“Meta” = above, superior, beyond

Some History

• Theoretical design by Victor Veselago in 1968– Predicted metamaterials act in exact opposite manner

than natural materials (like negative refractive index)

• Dr. John Pendry showed practical method of making metamaterials in 1999

V. G. Veselago

Sir John Pendry

http://cobweb.ecn.purdue.edu/~ece695s/Lectures/Lecture_15.pdf

How Does it Work?Normally, waves propagate and

interact with different media according to Snell’s Law

Metamaterials “Grab” waves and smoothly redirects them due to negative index of refraction

Material units must be small relative to the wavelength being manipulated

http://www.newscientist.com/blog/technology/labels/physics.html

Types of Metamaterials

• Electromagnetic– Transverse waves

• Acoustic– Longitudinal waves

• Seismic– Transverse and Longitudinal waves

Electromagnetic MetamaterialsNegative Refractive Index

http://www.imagico.de/pov/metamaterials.html

Refractive index

Electric permittivity

Magnetic permeability

Electromagnetic Metamaterials• Antennas– Negative index of refraction means more wave bending

which means smaller antenna (few mm)

http://www.metacloak.net/FractalMetamaterialMonopoleAntennaWhatWeDid.pdf

―Can double frequency range

―Increase radiated power

Electromagnetic Metamaterials

• Invisibility– Visible light waves must be

manipulated

Cloak ONCloak OFF

http://cobweb.ecn.purdue.edu/~ece695s/Lectures/Lecture_16.pdf

Acoustic Metamaterials

• Acoustic waves are different than electromagnetic waves– Longitudinal waves rather than

Transverse waves• Common physical concepts of waves

– Wave vector– Wave impedence– Power flow

• Negative Refractive index– Negative Mass Density – Negative Bulk Modulus

Refractive indexBulk Modulus

Mass Density

Acoustic Metamaterials

• Soundproof Room• Invisible Submarines (Sonar Blocking)• Seismic Metamaterials

- Negate the destructive effect of seismic waves on surface structures

- Requires the decoupling of longitudinal pressure waves and transverse shear waves, redirecting them around a cylindrical metamaterial cloak

Creation of Metamaterials

• Contact Photolithography used for larger nanomaterials

• Electron Beam Lithography used for smaller, more detailed structures

http://www.memsnet.org/mems/processes/lithography.htmlhttp://en.wikipedia.org/wiki/File:Left-handed_metamaterial_array_configuration.jpg

Limitations

• Small wavelengths require very small units

• Must be able to handle range of wavelengths for some applications– Frequency Selective Surfaces

(FSS aka Tunable)

http://www.joeruff.com/artruff/physics/Light/emspec.gif

Further Reading

Purdue university—Nanophotonics & Metamaterials ECE 695s

http://cobweb.enc.purdue.edu/~ece695s

D.R. Smith at Duke University—

http://people.ee.duke.edu/~drsmith/pubs_smith.htm

Questions?