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OPTICAL NANOANTENNA

PRESENTED BY:-PAYAL PRASAD

REGD. NO.-1101227499

Department of Electronics and Telecommunication EngineeringC. V. Raman College Of Engineering, Bhubaneswar

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CONTENTS• INTRODUCTION• DIFFERENCE BETWEEN RF AND NANOANTENNA• HISTORY OF NANOANTENNA• THEORY OF OPERATION• STRUCTURE• PRODUCTION• ADVANTAGES OF USING NANOANTENNA• APPLICATIONS• LIMITATIONS• CONCLUSION• REFERENCES

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INTRODUCTION

An antenna is a part of a system designed totransmmit or receive electromagnetic waves. This device is able to convert the radiation energy ofthe propagating wave into localized energy andvice versa.Optical nanoantennas are important devices forconverting propagating radiation into confined orenhanced fields at nanoscale.

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DIFFERENCE BETWEEN RF AND OPTICAL NANOANTENNA

• RF antennas have feature size of the order of several centimeters whereas optical antennas with that of order of a few hundred nanometers.

RF Antenna Optical nanoantenna

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• In RF antenna conduction phenomena dominates.However, in optical nanoantenna conductivity is lower and polarisation and displacement plays important role.

• Unlike RF antennas, optical antennas need specific design for each application

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HISTORY OF NANOANTENNA

• 1973 : Robert Bailey and James C. Fletcher, received a patent for an “electromagnetic wave converter” similar to modern nanoantenna.

• 1984 : Alvin M. Marks received a patent for a device stating the use of sub-micron antennas for the direct conversion of light power to electrical power.

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• 1996 : Guang H. Lin reported resonant light absorption by a fabricated nanostructure and rectification of light with frequencies in the visible range.

• 2002 : ITN Energy Systems Inc. published a report

on their work on optical antennas coupled with high frequency diodes

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THEORY OF OPERATION• Production of standing-wave electrical current in the

finite antenna array structure by incident electromagnetic radiation .

• Absorption of the incoming EM radiation energy at the designed resonant frequency of the antenna.

• Generation of cyclic plasma movement of free electrons from the metal antenna.

• Free flow of electrons along the antenna generating alternating current at the same frequency as the resonance.

• Current flows towards the antenna feedpoint. • In a balanced antenna, the feedpoint is located at the

point of lowest impedance.

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Flow of THz currents to feedpoint of antenna

10FIGURE SHOWING STRUCTURE OF ANTENNA

Ground plane - reflector

Dielectric resonance layer

Antenna

ANTENNA STRUCTURE

Three main parts :•Antenna•Ground plane•Optical resonance cavity

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• Antenna-absorbs the electromagnetic wave, the

ground plane acts to, and the optical resonance cavity

• Ground plane-reflects the light back towards the antenna

• Optical resonance cavity- bends and concentrates the light back towards the antenna via the ground plane.

FUNCTIONS :

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PRODUCTION LITHOGRAPHY

Figure showing lithography process

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ROLL-TO-ROLL MANUFACTURING• Based on a master pattern• It mechanically “stamps” the precision pattern

onto an inexpensive flexible substrate • Creates the metallic loop elements • Idaho National Laboratories fabricated a

master template (10 billion antenna elements on 8-inch round silicon wafer)

Electron microscope image of master template

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ADVANTAGES OF USING NANOANTENNA

• High theoretical efficiency(greater than 85%)

• Nanoantenna arrays can be designed to absorb any frequency of light

• By varying the size of the nanoantenna, the resonant frequency of the nanoantenna can be engineered to absorb a specific wavelength of light

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APPLICATIONS

• Realization of compact optical sensors

• Designing of integrated optical switches and memories at the nanoscale

• Designing of nanolasers

• In solar cells and photomixers

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LIMITATIONS• Production : -Slow and expensive electron beam lithography -Parallel processing is not possible with e-beam lithography• Operational frequency : -High frequency light in ideal range of wavelength makes the use of Schottky diodes impractical - MIM diodes need more advances to operate efficiently at higher frequencies

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CONCLUSION

In spite of some of its limitations, opticalnanoantenna has come up with many advantages and applications and with a promising future scope also. Future work will focus on designing the nanoantenna structure for operation in other wavelengths.

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REFERENCES

• Andrea Alù and Nader Engheta, “Theory, Modeling and Features of Optical Nanoantennas”, Antennas and propagation,vol. 61,pp. 1508-1517,2013

• P. Muhlschlegel,H. J.Eisler, O. J. F. Martin, B. Hecht, andD.W. Pohl,“Resonant optical antennas,” Science, vol. 308, pp. 1607–1609, 2005.

• P. Bharadwaj, B. Deutsch, and L. Novotny, “Optical antennas,” Adv.Opt. Photon., vol. 1, pp. 438–483, 2009.

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THANK YOU