METAMATERIALS

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METAMATERIALS

• Atanu Banerjee
• Mechanical Aerospace Engineering
• Microelectronic Fabrication

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CONTENTS

• What is Metamaterial?
• Metamaterials Vs Natural Materials.
• Brief History of Metamaterial Research.
• Classification of Metamaterials.
• Applications of Metamaterials.
• Metamaterial RD.
• Conclusion.

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What is Metamaterial?

• The term Metamaterial is first coined by Roger M
  Walser, University of Texas at Austin in 1999.
• A Metamaterial(MM) is a macroscopic composite of
  periodic or non-periodic structure whose function
  is due to both the cellular architecture as well
  as the chemical composition.
• They exhibit properties generally not found in
  nature.
• Figure Two typical metamaterial structures in
  the microwave regime. (a) A periodic structure,
  which is equivalent to a homogeneous medium. (b)
  A non-periodic structure, which is equivalent to
  an inhomogeneous (gradient) medium.

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Metamaterials Vs Natural Materials

• Most of the natural materials occur at discrete
  points, so most of the material properties have
  to be realized using metamaterials.
• Metamaterials gives us the opportunity to realize
  all possible material properties by designing
  different cellular architecture and using
  different material substrates.

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Metamaterials Vs Natural Materials

• Possible unique functionalities for
  Metamaterials
• the point µ -µ0 and e -e0 represents an
  anti-air in the LHM region, which will produce a
  perfect lens.
• The point µ 0 and e 0 represents a nihility,
  which can yield a perfect tunneling effect.
• The line µ e in both RHM and LHM regions
  represents impedance-matching materials, which
  have perfect impedance matching with air,
  resulting no reflections.

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Brief History of Metamaterial Research

• At the end of 19th century there had been
  extensive search for artificial material for
  manipulating electromagnetic waves.
• Theoretical proposal of Left-handed material was
  first done by Veselago in 1968.
• Mandelshtam published first on negative
  refraction followed by Malyuzhinets in 1951 who
  studied Sommerfield condition on backward wave
  media.
• Pendry et al in 1996 used an artificial wired
  medium whose permittivity is negative to realize
  artificial electric plasma, followed by this in
  1999 magnetic plasma is realized whose
  permeability is negative, using split-ring
  resonators (SRR).
• In 2005 Smith et al realized gradient refractive
  index medium to bend electromagnetic waves. In
  2006 optical transformation is proposed to
  control and manipulate electromagnetic waves and
  proposition of invisible cloak.

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Classification of Metamaterials

• 1) Negative Index Materials.
• 2) Single negative materials.
• 3) Electromagnetic bandgap materials.
• 4) Double positive medium.
• 5) Bi-isotropic and Bi-anisotropic metamaterials.
• 6) Chiral metamaterials.

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Application of Metamaterials
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Terahertz Modulators

• Natural materials do not respond to Terahertz
  frequency, also called Terahertz gap.
• A high passive modulation of the LC resonance has
  been achieved which can used to design terahertz
  modulators.
• -Zhang et al., OSU

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Super Lens

• The light emitted or scattered from an object
  includes not only propagating waves but also
  evanescent waves, which carry the subwavelength
  detail of the object.
• If a lens made of NIM is placed close to an
  object, the near-field evanescent waves can be
  strongly enhanced across the lens.

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Super Lens

• By completely recovering both propagating and
  evanescent waves in phase and amplitude, a
  perfect image is created which is not limited by
  diffraction.

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Metamaterial Absorber

• It uses the loss components of permittivity and
  magnetic permeability to realize a medium which
  has high radiation absorption ratio.
• They have advantages over conventional absorbers
  on enhanced miniaturization, increased
  adaptability and effectiveness.
• These have application in emitters, sensors,
  spatial light modulators, infrared camouflage,
  thermophotovoltaics, etc.

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Cloaking Device

• Metamaterials direct and control the propagation
  and transmission of specified parts of the light
  spectrum and demonstrate the potential to render
  an object seemingly invisible.
• Incident waves are guided around them without
  being affected by the object itself.

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Elastic Metamaterials

• It is defined as a new design for elastic
  metamaterials that can behave either as liquids
  or solids over a limited frequency range may
  enable new applications based on the control of
  acoustic, elastic and seismic waves.
• These can be acoustic metamaterials or can be
  seismic.

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RD in companies

• American Government
• 1. Oak Ridge National Laboratory's Optical
  Metamaterials Program, which focuses only on
  energy related challenges. Research focus
  Photovoltaics, LED Lighting, Thermal PV, Optical
  Microscopy, Sensors, etc.
• 2. U.S. defence focuses mainly on cloaking
  and stealth technology through metamaterials.
• EoPlex Technologies
• Micro Metamaterial antenna which
• shows high efficiency.
• MIT discovered lens for radio waves.

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Conclusion

• Theoretically metamaterial can have desired value
  of µ and e. Hence they can different properties
  and put to different applications.
• It is due to Metamaterials that several phenomena
  that would undoubtedly have been considered
  science fiction only a few years ago have been
  explicitly demonstrated.
• Though, many fascinating linear and nonlinear
  phenomena taking place in metamaterials have been
  theoretically predicted that still remain to be
  experimentally demonstrated.
• With the improvement of micro nano-fabrication
  techniques metamaterials will become efficient
  and cheap.

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