Alexandra Boltasseva, Assistant Professor

Projects


Nate and Sasha in the nanophotonics lab

Alternative Plasmonic Materials

Primary Contacts: Nate Kinsey, Jongbum Kim
Additional Contacts: Bivas Saha, Dr. Marcello Ferrera,
Naresh Emani, Aveek Dutta, Sajid Choudhury
Advisors: Prof. Alexandra Boltasseva
Collaborators: Prof. Tim Sands, Prof. Vladimir Shalaev

Short project description:

Plasmonics is a research area merging the fields of optics and nanoelectronics by confining light with relatively large free-space wavelength to the nanometer scale -thereby enabling a family of novel devices. Current plasmonic devices at telecommunication and optical frequencies face significant challenges due to losses encountered in the constituent plasmonic materials. These large losses seriously limit the practicality of these metals for many novel applications. We are now in the process of finding materials with improved optical performance, as well as applying these new materials to novel devices. These materials include transparent conductive oxides (TCOs) such as indium tin oxide (ITO), gallium zinc oxide (GZO), and aluminum zinc oxide (AZO) and metallic nitrides such as titanium nitride (TiN), zirconium nitride (ZrN), hafnium nitride (HfN). TCOs have been shown to be effective plasmonic materials in the infrared region while transition metal nitrides extend into the visible spectrum. These materials are currently being used by the Boltasseva Group in novel plasmonic applications such as integrated plasmonic devices, tunable plasmonics, and particle trapping.

Selected Papers:

  1. G. V. Naik, V. M. Shalaev, A. Boltasseva, Alternative Plasmonic Materials: beyond gold and silver, Advanced Materials, vol. 25, no. 24, pp. 3264-3294, 2013. (*Inside Cover picture, highlighted by Purdue News*)
  2. G. V. Naik, J. L. Schroeder, X. Ni, A. V. Kildishev, T. D. Sands, A. Boltasseva, "Titanium nitride as a plasmonic material for visible and near-infrared wavelengths," Optical Materials Express 2 (4), 478-489 (April 1 2012) (*Top OSA download in April 2012, highlighted in OSA press release and key industry media outlets Science Daily, NSF Science 360, Red Orbit, Photonics.com, April 2012*)
  3. J. B. Khurgin and A. Boltasseva, Reflecting upon the losses in plasmonics and metamaterials, MRS Bulletin, vol. 37, no. 8, pp. 768-779, 2012. (*Invited*)
  4. A. Boltasseva and H. Atwater, Low-loss plasmonic metamaterials, Science Perspective, Science, vol. 331, pp. 290-291, 2011. (*Featured in Nature photonics 5, 139-140, 2011 and number of scientific and technological websites*)
  5. G. V. Naik, J. Kim, A. Boltasseva, Oxides and nitrides as alternative plasmonic materials in the optical range, Optical Materials Express, vol. 1, no. 6, pp. 1090-1099, 2011. (*Invited*) (*Top downloaded until 2013, Highlighted in OSA News Release, September 22, 2011*)
  6. P. R. West, S. Ishii, G. V. Naik, N. K. Emani, V. M. Shalaev, A. Boltasseva, Searching for better plasmonic materials, Laser & Photonics Reviews, vol. 4, no. 6, pp. 795-808, 2010. (*Cover picture, highlighted by Purdue News*)
  7. G. V. Naik, B. Saha, J. Liu, S. M. Saber, E. Stach, J. MK Irudayaraj, T. D. Sands, V. M. Shalaev, A. Boltasseva, "Epitaxial superlattices with titanium nitride as a plasmonic component for optical hyperbolic metamaterials," submitted to PNAS (2013)
  8. B. Saha, G. Naik, V. P. Drachev, A. Boltasseva, E. E. Marinero, T. D. Sands, "Electronic and optical properties of ScN and (Sc,Mn)N thin films deposited by reactive DC-magnetron sputtering", Journal of Applied Physics 114 (6), 063519, DOI: 10.1063/1.4817715 (August 14 2013
  9. G. V. Naik, J. Liu, A. V. Kildishev, V. M. Shalaev, A. Boltasseva, "Demonstration of Al:ZnO as a plasmonic component of near-infrared metamaterials," Proceedings of the National Academy of Sciences 109 (23), 8834-8838 DOI: 10.1073/pnas.1121517109 (June 5 2012

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Dynamic Plasmonics with Graphene

Primary Contacts: Naresh Emani
Additional Contacts: Di Wang, Krishnakali Chaudhuri
Advisors: Prof. Alexandra Boltasseva, Prof. Alexander Kildishev, Prof. Vladimir Shalaev
Collaborators: Prof. Yong Chen

Short project description:

Plasmonics offers an exciting route to sub-wavelength optoelectronics by confining the optical fields below the diffraction limit. This is achieved by employing metal nanostructures resonant at a particular optical wavelength. Dynamic control of these plasmonic resonances at optical wavelengths is critical for many applications like integrated modulators and switches. In our group we are exploring the many exciting possibilities that result from real-time tuning of plasmonic resonances using 2D materials like graphene and transparent conducting oxides like AZO, GZO and ITO.

Graphene – a perfect 2D material consisting of single monolayer of carbon atoms, has some fascinating electrical and optical properties. We exploited the highly tunable interband transitions in graphene to dynamically modulate the plasmonic resonance in bow-tie nanoantennas and Fano resonant plasmonic nanostructures. We have also developed an accurate time domain model for performing numerical simulations.

Papers:

  1. Naresh K. Emani, Ting-Fung Chung, Alexander V. Kildishev, Vladimir M. Shalaev, Yong P. Chen, Alexandra Boltasseva, “Electrical modulation of Fano resonance in plasmonic nanostructures using Graphene”, Nano Letters 14 78 (2014).
  2. N. K. Emani, T.-F. Chung, X. Ni, A. V. Kildishev, Y. P. Chen, A. Boltasseva, Electrically tunable damping of plasmonic resonances with graphene, Nano Letters, vol. 12, pp. 5202-5206, 2012.
  3. L. J. Prokopeva, N. K. Emani, A. Boltasseva, and A. Kildishev, "Time Domain Modeling of Tunable Response of Graphene," in CLEO: 2013, San Jose, California, 2013, p. QTh1A.8.
  4. N. K. Emani, T.-F. Chung, L. Prokopeva, A. Kildishev, Y. Chen, and A. Boltasseva, "Tuning Fano Resonances with Graphene," in CLEO: 2013, San Jose, California, 2013, p. CW3O.4.

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Integrated Plasmonic Devices with Alternative Materials

Primary Contacts: Nate Kinsey
Additional Contacts: Dr. Marcello Ferrera
Advisors: Prof. Alexandra Boltasseva
Collaborators: Prof. Vladimir Shalaev, Prof. Sergey Bozhevolnyi

Short project description:

In order to continue the rapid increase the computation technologies, additional solutions should be investigated to supplement current microelectronic chips. One of the most promising technologies is light. Plasmonic devices, which couple light to the oscillations of free electrons at a metal-dielectric interface, provide several advantages over photonic solutions. Plasmonic devices can have reduced coupling loss to ultra-compact active devices (modulators, sensors, switches, etc), have a large sensitivity to the metal-dielectric surface, and can carry both electrical and optical signals. Our research is focused on realizing high-performance devices such as low-loss waveguides, ultra-compact modulators, and sensors using a practical material platform (titanium nitride, doped zinc oxide, and supporting materials) that are compatible with standard semiconductor fabrication techniques. We collaborate with Dr. Bozhevolnyi from the University of Southern Denmark on this project.

Papers:

  1. N. Kinsey, M. Ferrera, G.V. Naik, V.E. Babicheva, V.M. Shalaev, A. Boltasseva, “Experimental demonstration of titanium nitride plasmonic interconnects,” Optics Express in Press, April 2014.
  2. N. Kinsey, M. Ferrera, V.M. Shalaev, A. Boltasseva “A Platform for practical plasmonics,” SPIE Newsroom, in press, April 2014.
  3. V. Babicheva, N. Kinsey, G. Naik, M. Ferrera, A. Lavrinenko, V.M. Shalaev, and A. Boltasseva, “Towards CMOS-compatible nanophotonics: Ultra-compact modulators using alternative plasmonic materials,” Optics Express, vol. 21, no. 22, 2013.
  4. N. Kinsey, M. Ferrera, G. Naik, A. Kildishev, V. Shalaev, A. Boltasseva, “Low-Loss Plasmonic Titanium Nitride Strip Waveguides,” CLEO, 2014.
  5. V. Babicheva, N. Kinsey, G. Naik, M. Ferrera, A. Lavrinenko, V. Shalaev, A. Boltasseva, “CMOS Compatible Ultra-Compact Modulator,” CLEO, 2014.

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Nonlinear Optical Properties of Alternative Plasmonic Materials

Primary Contacts: Nate Kinsey
Additional Contacts: Clayton DeVault , Dr. Marcello Ferrera
Advisors: Prof. Alexandra Boltasseva, Prof. Vladimir Shalaev
Collaborators: Prof. Carl Bonner, Prof. Vladimir Gavrilenko, Prof. Alexander Kildishev

Short project description:

Metals are well known to have large third order nonlinearites, useful for applications in sensing, frequency conversion, and others. However, most metals are also limited for nonlinear use due to their low melting point and propensity for damage with the high fields required for nonlinear optics. The transition metal nitride family (titanium nitride, zirconium nitride, hafnium nitride, and tantalum nitride) are ceramics and can withstand significantly larger temperatures than noble metal films. In addition, they are biocompatible and CMOS compatible. These properties make them ideal for applications in biological/medial sensing and integrated nonlinear optics applications. Our goal is to study the third order nonlinear properties of these materials using the z-scan technique and to compare them to currently known metals. With a better understanding of the nonlinear properties of this family of materials, we hope to develop novel sensing and integrated nonlinear devices. We collaborate with Dr. Carl Bonner and Dr. Vladimir Gavrilenko from Norfolk State University on this project.

Nonlinear Optical Properties of Alternative Plasmonic Materials

Papers:

  1. N. Kinsey, A. Boltasseva, V.M. Shalaev, C.E. Bonner, V.I. Gavrilenko, "Nonlinear Optical Properties of TiN," submitted to Optics Letters, 2014.

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Transparent Conductive Oxides (TCOs) for Metasurface and Epsilon-Near-Zero (ENZ) Applications

Primary Contacts: Jongbum Kim, Aveek Dutta
Additional Contacts: Sajid Choudhury, Katie Kitamura
Advisors: Prof. Alexandra Boltasseva
Collaborators: Prof. Nader Engheta, Prof. Andrea Alu, Prof. Hossein Mosallaei,
Prof. Vladimir Shalaev, Prof. Alexander Kildishev

Short Project Description:

Artificial metasurface is considered as alternative component for three dimensional metamaterials due to its simplicity. Using low-loss plasmonic materials such as transparent conducting oxides (TCO) as alternatives to gold or silver, it is possible to have plasmonic metasurfaces with reduced losses in the near Infrared wavelength. Conventional nanofabrication techniques are employed to realize the metasurface, thereby enabling easy integration of metasurfaces into nanophotonic devices. In addition, thermal and electrical tunability of TCOs offer great possibility to realize switchable metasurfaces.

Epsilon-near-zero (ENZ) materials are the optical materials classified by a real part of the dielectric function close to zero. The resonance of nanoantenna on the ENZ layer can be influenced by the optical properties of ENZ materials. The resonant wavelength and the radiation at plasmon resonance are both dictated by the substrate to a significant extent. ENZ layer isolates the effect of substrate on the nanoantenna by diverting all the radiation into the upper plane and clamping the resonance of the antennas to the ENZ wavelength. In our experiments, AZO and GZO layer serves as an ENZ materials in the near-infrared (?=1.2 and 1.3 µm).

Transparent Cconductive Ooxides

Papers:

  1. J. Kim, G. V. Naik, N. K. Emani, U. Guler, A. Boltasseva, “Plasmonic Resonances in Nanostructured Transparent Conducting Oxide Films,” IEEE Journal of Selected Topics in Quantum Electronics 19, 4601907, 2013 (*invited*)
  2. J. Kim, Y. Zhao, G. Naik, N. Emani, U. Guler, A. Kildishev, A. Alu, A. Boltasseva, ''Nanostructured Transparent Conductive Oxide Films for Plasmonic Applications,'' contribution QTh3B.8, CLEO/QELS 2013, San Jose, CA, USA, June 9-14, 2013
  3. J. Kim, B. Memarzadeh, A. Dutta, S. M. Choudhury, A. V. Kildishev, H. Mosallaei, and A. Boltasseva, “GZO/ZnO Multilayered nanodisk metasurface to engineer the plasma frequency” CLEO, 2014
  4. J. Kim, Y. Zhao, A. Dutta, S. M. Choudhury, A. V. Kildishev, A. Alu, and A. Boltasseva, “Nanostructured Transparent Conducting Oxide Films for Polarization Control with Plasmonic Metasurfaces” CLEO, 2014

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Hybrid Electro-Plasmonic Tweezers

Primary Contacts: Justus Ndukaife
Additional Contacts: Dr. Urcan Guler
Advisors: Prof. Alexandra Boltasseva
Collaborators: Prof. Alexander Kildishev, Prof. Vladimir Shalaev, Prof. Steve Wereley

Short Project Description:

Plasmonic trapping offers an exciting route to trapping of nano-scale objects due to possibility of confining electromagnetic field within subwavelength dimensions, which is not readily accomplished with diffraction-limited laser tweezers. However, excitation of localized surface plasmons is normally accompanied by resonant light absorption, which results in local heating around plasmonic nanostructures. While efficient heat generation by plasmonic particles is very useful for certain applications like plasmonic photothermal therapy, it has so far been considered undesirable in plasmonic tweezers, due to the generation of increased Brownian motion, thermophoresis, and convection, which acts to prevent stable trapping of particles. We ask the question: can the localized heating or (thermal hot-spots) work in a synergistic manner with optical hot spots? To address this question, we are coupling plasmonics with AC electrokinetics to design plasmonic tweezers that efficiently utilize not only the optical hot-spots but also thermal hot spots for particle trapping. We hope to use this approach to overcome the diffusion-limited transport of particles to trapping sites, which would have important applications for biosensing, while achieving stable trapping of particles. We explore trapping and nanopositioning of single nanodiamonds hosting nitrogen vacancy centers to plasmonic optical hotspots.

Hybrid Electro-Plasmonic Tweezers

In addition we explore Fano resonances in plasmonic nanostructures, and the trapping of nanoscale objects with such Fano resonant nanoantennas which could find applications in biological and chemical sensing. We collaborate with Prof. Steve Wereley (School of Mechanical Engineering Purdue University) on this project.

Papers:

  1. Justus Ndukaife, Avanish Mishra, Urcan Guler, George Nnanna, Steve Wereley, Alexandra Boltasseva, "Photothermal heating enabled by plasmonic nanoantennas for electrokinetic manipulation and sorting of particles", submitted to ACS Nano.
  2. Justus Ndukaife, Avanish Mishra, Urcan Guler, George Nnanna, Steve Wereley, Alexandra Boltasseva, "Photothermal heating enabled by plasmonic nanoantennas for electrokinetic manipulation and sorting of submicron particles", CLEO 2014.

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Glancing Angle Deposition

Primary Contacts: Paul West
Additional Contacts: Zhouxian Wang
Advisors: Prof. Alexandra Boltasseva, Prof. Vladimir Shalaev
Collaborators: Prof. Alexander Kildishev

Short Project Description:

While conventional physical vapor deposition evaporators deposit material at near-normal angle of incidence, the Glancing Angle Deposition system allows thin films to be deposited onto three-dimensional structures with non-conformal geometries at very sharp angles (up to 90 degrees). Additionally, our evaporator is fully automated - with computer controlled 2 axes of rotation, deposition monitoring, and source selection. Automation of the system allows for the many multi-layer deposition required for the future generation of optical metamaterial devices.

One example of a sample fabricated with glancing angle deposition is shown below. This image shows the result of silver deposited on a 5 micron silicon sphere at a glancing angle. As can be seen in the image, a gradient thickness of silver is distributed along the surface of the sphere, with each thickness providing unique optical properties.

Glancing Angle Deposition

Papers:

  1. P.R. West, N. Kinsey, M. Ferrera, A. Kildishev, V.M. Shalaev, A. Boltasseva, “Engineered Outcoupling of Adiabatically Tapered Hyperbolic Metamaterials,” CLEO, 2014.

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