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METAMATERIALS and NEGATIVE REFRACTION
Nandita Aggarwal
Laboratory of Applied Optics
Ecole Polytechnique de Federal Lausanne
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Presentation Overview
Introduction to negative refraction
Theoretical explanation
Experimental verification
Different structures as metamaterials SRR structure
S-SRR structure
EX-SRR structure
Omega type structure
Negative refraction in optical regime
Applications Super lenses High directive Antennas
Cloak invisibility
References
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Reversing light : Negative refraction
Timereversal
NegativeRefraction
(Reversal ofspatial evolution
of phase)
Time reversalandnegativerefraction
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Disobeying Snells Law: Lefthanded materials
Light makes negative angle with the norma
Poynting vector has the opposite sign
to the wave vector
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NegativeRefraction
Practical demonstration of negative Refraction
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Theoretical Explanationin brief
Assumption: Wavelength used > spacing and size ofthe unit cell.
Composite can be assumedhomogeneous.
(eff.) and (eff.) are structure dependent.
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ExperimentalVerification
Al plates separation: 1.2 cm
Radius of circular plates: 15 cm
Detector was rotated around the circumference of circle in 1.5
degree steps
LHM material (Prism)Unit cell : 5mm
Operating wavelength : 3cm (8-
12 GHz)
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ExperimentalVerification
Refractive index of teflon : 1.4+- 0.1
Refractive index of LHM : -2.7
+-0.1
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Split Ring Resonators + Metallic Wires
S shaped Split Ring Resonators
Extended S shape Split Ring Resonator
Fish scale
Omega type
Different Structures asMetamaterials
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Ring Resonator + Metallic Wires
Dispersion curve for the parallel polariraztion.Dashed line shows the SRR with wires placeduniformly between them.
Split RingResonator
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aped Split Ring Resonators
3-D plot of S-shapedSRR
Equivalent electrical circuit ofSRR
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aped Split Ring Resonators
Effective permeability for the S-SRR structure in the case of F1 =F2 = F = 0.3
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aped Split Ring Resonators
Two unit cells of a periodic arrayed structure (a) A broken rodsarray, (b) A capacitance-enlarged rods array, (c) A S- shaped rods
array
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aped Split Ring Resonators
The real part of the effective permittivitymeasured for configuration (b) and (c) withthe change in value of h.
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ded S-shaped Split Ring Resonators
The ES-SRR structure with a period of 2 rings in the zdirection and its analytical model
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ded S-shaped Split Ring Resonators
Extended S-ShapedSRR
Normal S-Shaped SRR
Effective Permeability Vs.Frequency
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ega type structures
Unitcell
Picture of metamaterialactually realized and measured
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ega type structures
Snell refractionexperimental results
3-D result with the three axesrepresenting detected power in mW,
Frequency in GHz and angle in degrees.
2-D curve extracted at 12.6 GHz f3-D results.
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tive refraction in optical regime
Detailed history of development of magnetic resonance frequency
as a function of time
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Applications
Superlens
Highly directive
Antenna
Cloaking
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Superlens
The electric component of the field will be given by some 2D fourier
expansion:
Propagating waves:
Evanescent waves:
Diffraction limit of the lens:
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Superlens
With this new lens, both propagating and evanescent wavescontribute to the resoltuion of the image
Enhancement of evanescent waves i.e. amplification (thoughevanescent waves carry no energy still the results aresurprising) of these waves was proven by Sir John Pendry in2000.
Negative Refraction Makes a Perfect
Lens
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Superlens
Perfect Lensing in Action
A slab of negative material effectively removes an equalthickness of space for
(A) The far field
(B) The near field , translating the object into a perfect image
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Highly DirectiveAntennas
Geometricalinterpretation of theemission of a sourceinside slab of
metamaterial havingoptical index close tozero
Construction in reciprocalspace
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Cloaking
"I still think it is a distant concept, but this latest structure does showclearly there is a potential for cloaking -- in the science fiction sense become science fact at some point," says Smith.
Invisible Man become a reality?
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Cloaking
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Cloaking
Snapshots of time-dependent , steady-state electric fieldpatterns.
Cu cyllinder is cloaked
A: Simulation of cloak with exact material properties
B: Simulation with reduced material properties
C: Experimental measurment of bare conducting cyllinder
D: Experimental measurments of cloaked conducting cyllinder
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References
1. J.B Pendry Physics review Letters, Vol. 85, no. 18
(3966-3969)
2. John B. Pendry and David R. Smith DRS&JBP
(final).doc, Physics Today
3. Costas M. Soukoulis, Stefan Linden, Science, Vol
315, (47-49)
4. H.S Chen et al. PIER 51, 231-247, 2005
5. D. Schurig, J.J. Mock, Science, Vol 314 (977-979);
2006
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THANK YOU
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