Optical Antennas
Tajim Md Hasibur Rahman
Student ID: 35176358
Date: 13.12.2017
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Contents
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Introduction
Motivation
Classification of Optical Antennas
Near Field Optical Probes
Optical Resonant Antennas
Difference between Optical Antenna & RF Antenna
Recent Success
Conclusion
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Introduction:
Optical “Antenna”
• What is Optical Antenna?
• What is Antenna?
Figure 1: Field distribution of accelerated charge*
*http://www.antenna-theory.com/basics/whyantennasradiate.php
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Introduction: (cont.)
Antenna & Wavelength
• Is any transmission line antenna?
Figure 2: (a) Transmission line, (b) Antenna [6]
• Wavelength – the most important parameter
Figure 3: Current distributions in antenna for different lengths [6]
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Introduction: (cont.)
Optical Nano-antenna
• Optical Regime – Nano Antenna
Figure 5: Optical Rectifying Antenna**
Figure 4: A 70m dish antenna situated in NASA’s
Jet Propulsion Laboratory (JPL)*
*http://www.antenna-theory.com/intro/main.php
**https://www.energymatters.com.au/renewable-news/optical-rectenna-solar-em5103/
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Motivation
• Why we need optical antenna?
• Light-Matter Interaction
– Maximum solar cell efficiency
46% (World record Dec’14 –
Collaboration effort of Soitec,
CEA-Leti, France & Fraunhofer ISE,
Germany).*
Figure 6: Solar Panel**
• Optical Nano-antenna applications:
– Solar Cell (energy efficiency)
– Photo-detector (SNR)
– Nano-imaging (resolution)
*https://en.wikipedia.org/wiki/Solar_cell_efficiency
**https://www.nrel.gov/workingwithus/re-photovoltaics.html
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Classification of Optical Antennas
1. Near Field Optical Probes
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First realization in 1980s
Experimentally proved 10 years later
Developed with respect to optical microscopy
“Nano Plasmonic Era”
2. Resonant Optical Antennas
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First proposed in 1997 by Robert Grober the bow-tie structure
A technology more advance than Optical Probes
Exploring various geometries started afterwards
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Near Field Optical Probes
• Structure & Physics
– Positioned in near field
– Electromagnetic field enhancement
due to surface plasmons
– The gap between the probes is
‘feed gap’
– Two approaches:
Figure 7: Gold Nano-shell Optical Probes*
a) Local scattering approach
b) Local excitation approach
• Advantages
– Overcoming diffraction barrier
– Increase resolution
Figure 8: Airy Disc**
*https://www.youtube.com/watch?v=nuJT1BN6sco
**https://en.wikipedia.org/wiki/Airy_disk
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Resonant Optical Antennas
• Structure & Physics
– Downscaled replicas of RF antennas
– Translation of RF antenna theory to nano-scale
– Requirement of nano-circuit theory
• Plasmonic Effect
• Displacement Effect
– Consequences of these effects
• Effective length > Physical length
• Advantages
Figure 9: Optical Nano-dipole Antenna
with Thevenin equivalent circuit model [7]
– Optimal conversion of localized field into propagating field
– Field line concentration on the gap
– Optimum impedance matching
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Difference between Optical Antenna
and Conventional RF Antenna
• Direct translation of RF antenna theory is not possible due to
– Physical operation
– Material property
– Wave matter interaction process
• Differences
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Conductivity
Plasmonic effect
Displacement effect
Loss & absorption
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Recent Success
•
Georgia Institute of Technology – World’s First Optical
Rectifying Antenna [9]
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The antenna matches with the energy of sunlight
Electricity conversion is done in world’s fastest rectifying diode
Claims that efficiency increased twice than today’s solar cells
(greater than 40%)
Simplicity in structure
Figure 10: Optical Rectifying Antenna*
*https://www.energymatters.com.au/renewable-news/optical-rectenna-solar-em5103/
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Conclusion
• A potential technology
• Comparatively new research field
• Prospective applications
– Efficient photovoltaics
– Photo detection
– Nano imaging
– Nonlinear signal conversion & information processing
• Probable replacement of RF Antennas
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References
[1] Bharadwaj, P., Deutsch, B. and Novotny, L., 2009. Optical antennas. Advances in Optics and Photonics, 1(3),
pp.438-483.
[2] Novotny, L., 2009. Optical Antennas A New Technology That Can Enhance Light-Matter Interactions.
[3] Novotny, L. and Stranick, S.J., 2006. Near-field optical microscopy and spectroscopy with pointed
probes. Annu. Rev. Phys. Chem., 57, pp.303-331.
[4] Klar, T.A., Jakobs, S., Dyba, M., Egner, A. and Hell, S.W., 2000. Fluorescence microscopy with diffraction
resolution barrier broken by stimulated emission. Proceedings of the National Academy of
Sciences, 97(15), pp.8206-8210.
[5] Novotny, L. and Van Hulst, N., 2011. Antennas for light. Nature photonics, 5(2), pp.83-90.
[6] Hecht, B., Muehlschlegel, P., Farahani, J.N., Eisler, H.J., Pohl, D.W., Martin, O.J. and Biagioni, P., 2006.
Prospects of resonant optical antennas for nano-analysis. CHIMIA International Journal for
Chemistry, 60(11), pp.765-769.
[7] Alu, A. and Engheta, N., 2013. Theory, modeling and features of optical nanoantennas. IEEE Transactions on
Antennas and Propagation, 61(4), pp.1508-1517.
[8] Hecht, B., Farahani, J., Mühlschlegel, P., Eisler, H.J., Pohl, D.W. and Martin, O.J., 2006. Resonant optical
antennas. In Proc. 9th Int. Conf. Near-field Optics and Related Techniques(Vol. 1, No. EPFL-CONF-175055, p.
114).
[9] Sharma, A., Singh, V., Bougher, T.L. and Cola, B.A., 2015. A carbon nanotube optical rectenna. Nature
nanotechnology, 10(12), pp.1027-1032.
[10] http://www.antenna-theory.com/
[11] https://www.energymatters.com.au/renewable-news/optical-rectenna-solar-em5103/
[12] https://en.wikipedia.org/wiki/Solar_cell_efficiency
[13] https://www.youtube.com/watch?v=nuJT1BN6sco
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Thank you
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Questions??
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