averitt slides
TRANSCRIPT
![Page 1: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/1.jpg)
Introduction to Metamaterials
Richard D. Averitt
![Page 2: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/2.jpg)
Research Themes
“Equilibrium is when all of the fast stuff has happened, and all of the slow stuff hasn’t.” -‐Feynman
![Page 3: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/3.jpg)
Metamaterials: a new field
J. B. Pendry, A. J. Holden, D. J. Robbins, W. J. Stewart, “Magnetism from conductors and enhanced non-linear phenomena,” IEEE Trans. MTT 47, 2075 (1999)
D. R. Smith, et al., Phys. Rev. Lett. 84, 4184 (2000)
![Page 4: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/4.jpg)
New York Times, 2007
The Irresistible Fantasy of the Invisible Man, and Machine
![Page 5: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/5.jpg)
The Chameleon
![Page 6: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/6.jpg)
The Stealth Fighter: Invisible to Radar?
Very small radar cross section: shape and absorbing paint
![Page 7: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/7.jpg)
From: http://www.star.t.u-tokyo.ac.jp
A camera and a projector
![Page 8: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/8.jpg)
by Lee & Kirby (1961)
"... she achieves these feats by bending all wavelengths of light in the vicinity around herself ... without causing any visible distortion.” -- Introduction from Wikipedia
Fantastic 4: The Invisible Woman
![Page 9: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/9.jpg)
"... it was an idea ... to lower the refractive index of a substance, solid or liquid, to that of air — so far as all practical purposes are concerned.” -- Chapter 19 "Certain First Principles"
The Invisible Man by H.G. Wells (1897)
Key Concept: The Refrac2ve Index à n
Velocity of light in free space: c
In a material: c/n
![Page 10: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/10.jpg)
The bending of light due to the gradient in refractive index in a desert mirage
Mirage: Optical Illusion
![Page 11: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/11.jpg)
Tearing Space: conformal map
Wegner, Linden in Physics Today, 2010
We can’t tear space:
Mimic by shaping the refrac2ve index n
![Page 12: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/12.jpg)
The New York Times; 3-‐D model by Christoph Hormann and Gunnar Dolling, Karslruhe University
![Page 13: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/13.jpg)
Snell’s Law
• Reflection: θi = θr
• Refraction: n1sinθi=n2sinθt
The refraction beam is at the other side of the incident normal.
![Page 14: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/14.jpg)
NegaUve RefracUve Index: A long history
• A. Schuster, An IntroducUon to the Theory of OpUcs, (1904) -‐ Discussed in the context of anomalous dispersion as occurs at any absorpUon band.
• L.I. Mandelshtam, May 5 1944 (last lecture)
“In fact, the direction of wave propagation is determined by its phase velocity, while energy is transported at the group velocity.” - Translated by E. F. Keuster
![Page 15: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/15.jpg)
PosiUve RefracUon
X. Huang, W. L. Schaich, Am. J. Phys.72, 1232 (2004)
![Page 16: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/16.jpg)
NegaUve RefracUon
X. Huang, W. L. Schaich, Am. J. Phys.72, 1232 (2004)
![Page 17: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/17.jpg)
Sir John Pendry – leading theorist in the area:
In convenUonal materials, the dielectric response derives from the consUtuent atoms. As discussed, negaUve or posiUve ε(ω) is possible over a broad spectral range. However, natural materials with a resonant magneUc permeability µ(ω) don’t exist above a few THz (e.g. FerromagneUc resonance in Fe at microwave frequencies, or anUferromagneUc resonance in MnF2 at ~2THz).
Pendry, Contemporary Physics
![Page 18: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/18.jpg)
-55
-50
-45
-40
-35
-30
-25
4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5
Tra
nsm
itted
Pow
er (
dBm
)
Frequency (GHz)
J. B. Pendry, A. J. Holden, D. J. Robbins, W. J. Stewart, “Magnetism from conductors and enhanced non-linear phenomena,” IEEE Trans. MTT 47, 2075 (1999).
Metamaterials: Expanding our Space
Pendry et al. suggested that an array of ring resonators could respond to the magnetic component light.
![Page 19: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/19.jpg)
LCR circuits
• A circuit with an inductor (L) and capacitor (C) saUsfies the same equaUon as the mass spring system for simple harmonic oscillaUon.
• If we added a resistor (R) that we get the damped oscillator equaUon.
– as for the mechanical oscillator, the soluUon can be
• under damped: ( γ < 2 ω0 ) • criUcally damped: ( γ = 2 ω0 ) • over damped: ( γ > 2 ω0 )
• We can choose the values of L, C, and R to determine which kind of damping we have.
![Page 20: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/20.jpg)
Comparison between mass-‐spring systems and LCR circuits.
![Page 21: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/21.jpg)
![Page 22: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/22.jpg)
γ is the full-‐width half maximum (fwhm) of the power absorpUon curve quality factor Q :
![Page 23: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/23.jpg)
Magnetic Metamaterials: Shaping a resonance
Dimensions < λ
01LC
ω =
Effective Medium: µ(ω)
![Page 24: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/24.jpg)
![Page 25: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/25.jpg)
The first negative index material, meta or otherwise!
D. R. Smith, W. J. Padilla, et al, Phys. Rev. Leh. 14, 234 (2000)
![Page 26: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/26.jpg)
Experimental Demonstration of NI
Microwave: ease of fabrication
R. A. Shelby, D. R. Smith, S. Schultz, Science 84, 4184 (2001)
![Page 27: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/27.jpg)
The Electromagnetic Cloak (2006)
![Page 28: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/28.jpg)
J. B. Pendry, et al., Science 312, 1780 (2006) D. Schurig, et al., Science, 314, 2006.
The Electromagnetic Cloak
Simulation Experiment
![Page 29: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/29.jpg)
Cloaking Other Waves: Sound, Water, Earth
The Cone of Silence
Would you believe?.........
![Page 30: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/30.jpg)
M. Farhat, S. Enoch, S. Guenneau, and A. B. Movchan, "Broadband cylindrical acoustic cloak for linear surface waves in a fluid", Physical Review Letters 101,.134501 (2008).
Cloaking Water Waves
![Page 31: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/31.jpg)
Cloaking Water Waves
![Page 32: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/32.jpg)
Metamaterials at BU
![Page 33: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/33.jpg)
Terahertz
• Microwave Electronics: Antenna, high speed transistor circuits for microwave generaUon, detecUon, control and manipulaUon ApplicaUons: wireless communicaUons, radar…
• Terahertz gap Progress in sources and detectors. Also need funcUonal devices such as filters, switches, modulators which largely do not exist
• Infrared and visible Photonics: Source: lasers, LEDs Detector: Photodiodes FuncUonal: lens, polarizer,
opUcal switch ApplicaUons: opUcal fiber communicaUons…
1 THz à 4 meV à 48K à 300 μm à 33 cm-1
![Page 34: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/34.jpg)
Terahertz Region of the EM Spectrum
B.B. Hu, M. Nuss, Opt. LeQ. 20, 1716 (1995)
![Page 35: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/35.jpg)
THz Metamaterials
36 µm X 36 µm 4 µm linewidth 2 µm gap
01LC
ω =
![Page 36: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/36.jpg)
Experimental Setup: THz-TDS
![Page 37: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/37.jpg)
Bi-material Cantilever Based Metamaterials A Mechanical Chameleon
Au / Silicon nitride cantilever arrays: Thermal Actuation
Phys. Rev. Lett. 103, 147410 (2009)
The SRRs are 72 µm X 72 µm with an in-plane periodicity of 100 µm and an overall dimension of 1 cm X 1cm.
![Page 38: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/38.jpg)
Turning On The Refractive Index Mechanically
Control of the EM response at the unit cell level
![Page 39: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/39.jpg)
Resonant Detectors Fabricated at 95 and 690 GHz
95 GHz 690 GHz
![Page 40: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/40.jpg)
95 GHz MM-Based Thermal Detector: Single Pixel Characterization
Spectrally Selective and Polarization Sensitive!
• Room T • Ambient • Optical Readout • 15 Hz
![Page 41: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/41.jpg)
![Page 42: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/42.jpg)
Magnetic Metamaterials
![Page 43: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/43.jpg)
3D Stand-up Metamaterials: Pure Magnetic Excitation at Terahertz Frequencies
(a)
(b)
(c)
(d)
(e)
(f)
(g)
Cu electroplaUng with Cu/Ti seed layers
![Page 44: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/44.jpg)
3D Stand-up Metamaterials: Pure Magnetic Excitation at Terahertz Frequencies
![Page 45: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/45.jpg)
Metamaterials
Sub-λ “LC” Resonators Array à effective n(λ)
Create complex materials by combining metamaterials with other materials including transition metal oxides
Correlated Electron Matter
Competing DOF Mode selec. excitationà
Phase control
![Page 46: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/46.jpg)
M. K. Liu, et al, Nature 487, 345 (2012)
![Page 47: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/47.jpg)
Field enhancement in the capacitive gaps
• Large field enhancement
• Extreme sub-λ regime
• Separation of E and H
![Page 48: Averitt slides](https://reader034.vdocuments.us/reader034/viewer/2022052603/55d035aabb61ebd3698b46e1/html5/thumbnails/48.jpg)
Above Damage Threshold: ~4 MV/cm
M. K. Liu, et al, Nature 487, 345 (2012)