metamaterials caleb hughes hassan ismail brett mccutchan eciv 303 11/30/2010
TRANSCRIPT
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?