integrated optical tornadoes for efficient light harvesting svetlana v. boriskina, selcuk yerci...
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Integrated optical tornadoes for efficient light harvestingSvetlana V. Boriskina, Selcuk Yerci & Gang Chen
NanoEngineering groupDepartment of Mechanical Engineering
Massachusetts Institute of Technology
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Cat. F5 tornado (Manitoba, Canada, June 2007)
Image credit: Juri Hahhal
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Ray picture dominates conventional thinking about light propagation
Image credit: Teresa Matfield
A. Mavrokefalos et al, Nano Lett. 12, 2792-2796, 2012
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Light trapping schemes typically rely on constructive interference of light rays
scattering
J. VanCleave, Colors & Thin-Film Interference, John Wiley & Sons, Inc.
Atwater & Polman, Nature Mater. 2010
field enhancement
waveguiding
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There is another way: making use of destructive interference
‘Black holes are where God divided by zero’Steven Alexander Wright
phase vortex
= indefinite phasezero intensity ))((exp)(),( tit rrUrE
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There is another way: making use of destructive interference
‘Black holes are where God divided by zero’Steven Alexander Wright
= indefinite phasezero intensity
Credit: iStockphoto.com/David Ciemny
))((exp)(),( tit rrUrE
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There is another way: making use of destructive interference
‘Black holes are where God divided by zero’
flow vortex
Steven Alexander Wright
phase vortex
Optical energy flows in the direction of the phase change
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Hydrodynamic analogy of light trapping
S.V. Boriskina, “Plasmonics with a twist,” in Plasmonics in metal nanostructures: Theory & applications ( Shahbazyan & Stockman eds.) Springer, 2013
Image credit: Teresa Matfield Image credit: http://www.forestwander.com
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Hydrodynamic analogy of light flow
Maxwell’s equations:
t
t
ΕJH
HE
H
E
0
S.V. Boriskina & B.M. Reinhard, Nanoscale, 4, 76-90, 2012
)()()()( rrrvr
)()()( rrvrv V
‘mass’ conservation:
momentum conservation:
Navier-Stokes-like equations:
(Madelung, 1926)
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Hydrodynamic analogy of light flow
Maxwell’s equations:
t
t
ΕJH
HE
H
E
0
S.V. Boriskina & B.M. Reinhard, Nanoscale, 4, 76-90, 2012
convective term
)()()()( rrrvr
)()()( rrvrv V
‘mass’ conservation:
momentum conservation:
potential created by the light trapping structure
material loss or gain
Navier-Stokes-like equations:
2|)(|)()( rUrr I
)(rv
‘Photon fluid’ density:
‘Photon fluid’ velocity:
(Madelung, 1926)
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How are optical tornadoes generated?
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By colliding several light beams with appropriate phases …
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… or by strategically positioning obstacles in the light flow path
S.V. Boriskina & B.M. Reinhard, Nanoscale, 4, 76-90, 2012
Zero intensity
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S.V. Boriskina & B.M. Reinhard, Nanoscale, 4, 76-90 (2012)W. Ahn, S.V. Boriskina, et al, Nano Lett. 12, 219-227 (2012)
Example of a vortex-pinning nanostructure
50-nm radius Au nanoparticles
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S.V. Boriskina & B.M. Reinhard, Nanoscale, 4, 76-90 (2012)W. Ahn, S.V. Boriskina, et al, Nano Lett. 12, 219-227 (2012)
Example of a vortex-pinning nanostructure
50-nm radius Au nanoparticles
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S.V. Boriskina & B.M. Reinhard, Nanoscale, 4, 76-90 (2012)W. Ahn, S.V. Boriskina, et al, Nano Lett. 12, 219-227 (2012)
Optical energy is circulating outside the metal volume!
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What is the origin of the strong field enhancement?
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Optical vortices generate local velocity fields
Tangential velocity ~1/r
r
)()()( rrvrv V
• compressible fluid• potential steady-
state flow• local convective
acceleration possible
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‘Photon fluid’ is convectively accelerated in the vortex velocity field…
)()()( rrvrv V
• compressible fluid• potential steady-
state flow• local convective
acceleration possible
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… and when threaded through nanoscale gaps, generates ‘hydraulic jumps’ - areas of high field intensity
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… and when threaded through nanoscale gaps, generates ‘hydraulic jumps’ - areas of high field intensity
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Vortex-pinning nanostructures are photonic analogs of turbopumps
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Optical vortices can be moved and ‘stretched’ by repositioning the obstacles
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Tunable or broadband light trapping possible
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Beyond light trapping …
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Nanoscale light switching
S.V. Boriskina & B.M. Reinhard, Opt. Express, vol. 19, no. 22, pp. 22305, 2011
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Nanoscale light switching
S.V. Boriskina & B.M. Reinhard, Opt. Express, vol. 19, no. 22, pp. 22305, 2011
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Nanoscale light switching
S.V. Boriskina & B.M. Reinhard, Opt. Express, vol. 19, no. 22, pp. 22305, 2011
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Nanoscale light switching
S.V. Boriskina & B.M. Reinhard, Opt. Express, vol. 19, no. 22, pp. 22305, 2011
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Nanoscale light switching
S.V. Boriskina & B.M. Reinhard, Opt. Express, vol. 19, no. 22, pp. 22305, 2011
HT2013-17406 ‘Surface Plasmon Enhanced Radiative Nanoscale Heat Transfer’ Thu, July 18, 3:58pm, Salon G
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Conclusions and outlook
• New way of trapping light by molding it into nanoscale vortices
• Higher field concentration than traditional schemes based on constructive interference
• Strong energy flow outside of the metal volume of nanoparticles – PV applications
• New way of designing light absorbers via the hydrodynamic analogy
Many thanks to
Prof. Gang Chen & MIT NanoEngineering group
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SOLID STATE SOLAR THERMAL ENERGY CONVERSION (S3TEC) CENTER
The audience