Projects

 

Refractory Plasmonics

Primary Contact: Dr. Urcan Guler
Additional Contacts: Jingjing Liu, Harshavardhanareddy Eragamreddy
Advisors: Prof. Vladimir M. Shalaev, Prof. Alexandra Boltasseva, Prof. Alexander Kildishev
Collaborators: Prof. Ernesto Marinero, Prof. Peter Bermel, Prof. Tim Sands, Prof. Ali Shakouri, Prof. Ted Norris, Prof. Oana Malis, Prof. Sergey Bozhevolnyi

Short project description:

Some of the proposed plasmonic applications require extreme operating conditions such as high temperatures and chemically aggressive environment. Conventional plasmonic materials such as noble metals bring limitations due to their lower melting point, softness etc. Refractory materials, exhibiting high melting points and chemical stability above 2000 oC, with plasmonic properties in the visible and near infrared regions can be the solutions to major problems hindering the improvement of potentially high-impact applications such as heat assisted magnetic recording (HAMR), solar/thermophotovoltaics (S/TPV) and solar thermoelectric generators (STEG).

Transition metal nitrides, in particular titanium nitride (TiN) and zirconium nitride (ZrN), are known as refractory materials and exhibit plasmonic resonances in the visible and near infrared regions. Nanoantennas made of refractory plasmonic materials can be employed as durable near field transducers for HAMR heads where antenna temperatures are estimated to be above 400°C. Furthermore, ultrathin broadband absorbers and selective emitters made of refractory plasmonic materials offer durability at higher temperatures and higher overall device efficiencies for S/TPVs and STEGs.

Papers:

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Plasmonic Titanium Nitride Powder

Primary Contact: Dr. Urcan Guler
Advisors: Prof. Vladimir M. Shalaev, Prof. Alexandra Boltasseva, Prof. Alexander Kildishev
Collaborators: Dr. Dmitry Zemlyanov, Dr. Alberto Naldoni, Dr. Swati Pol, Prof. Nicholas Kotov, Prof. Ted Norris, Dr. Vladimir Liberman, Prof. Boris N. Chichkov

Short project description:

Transition metal nitrides, particularly titanium nitride and zirconium nitride, exhibit plasmonic resonances in the visible and near infrared region of the electromagnetic spectrum. Combined with their optical properties similar to Au, additional superior material properties such as high melting point, corrosion resistance and hardness offer high potential for several plasmonic applications. In addition, TiN offers CMOS and bio-compatibility where application and process specific requirements are determinative.

Plasmonic properties and material superiority of TiN can be demonstrated with top-down fabrication methods for proof-of-concept studies. However, plasmonic powder of TiN is crucial for many practical applications. We investigate production techniques of TiN powders and their plasmonic properties for several applications such as plasmonic photothermal therapy, drug delivery, photocatalysis, and solar thermophotovoltaics.

Papers Published:

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Quantum Nanophotonics with Color Centers in Diamond

Primary Contact: Mikhail Y. Shalaginov, Dr. Simeon Bogdanov
Advisor:Prof. Alexander Kildishev, Prof. Vladimir Shalaev.
Additional Contact: Dr. Alexei S. Lagoutchev
Collaborators: Dr. Alexey V. Akimov (RQC)

Short project description:

Color centers in diamond are crystalline defects that share many quantum properties with single atoms. At the same time they are easier to manipulate than the latter and can be integrated into a solid state infrastructure. They are promising for realizing quantum devices such as nanoscale sensors, single-photon sources or quantum memories. Our research aims at discovering whether it is possible to draw on the promising potential of the fast developing field of nanophotonics in order to enhance or better harness the quantum properties of such systems. In particular, novel nanophotonic structures such as hyperbolic metamaterials and plasmonic waveguides are good candidates for increasing the color center's spontaneous emission rate and controlling the directionality of their emission in a broad frequency range. The broadband optical Purcell factor in plasmonic systems can be also used to control the spin readout. Conversely, the color centers' spin degree of freedom can simplify the measurement of the photonic density of states on the nanoscale. The use of CMOS-compatible epitaxially grown plasmonic materials in the design of plasmonic structures promises a new level of functionality for a variety of integrated room-temperature quantum devices based on diamond color centers.

In the scope of this project, we have examined different types of nanodiamonds and identified the characteristics that lead to optimal optical and chemical properties. We have demonstrated broadband enhancement of emission from nitrogen-vacancy (NV) center ensembles in nanodiamonds using conventional gold/alumina hyperbolic metamaterials (HMM). We have theoretically shown that planar multilayer HMM make single photon emission more directional. We have showed both the fluorescence lifetime reduction and the enhancement of single-photon emission from single NV centers in nanodiamonds coupled to an epitaxially grown CMOS-compatible HMM made of novel plasmonic materials TiN/AlScN. In our most recent work, we have studied the correlations between Purcell factor and optical measurements of NV’s spin state and the possibility to perform nanoscale sensing of photonic density of states using NV’s spin properties. Our results may enable CMOS-compatible integrated quantum devices operating at room temperature.

Quantum Nanophotonics with Color Centers in Diamond Project

Papers Published:

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Cloud Computing Nanophotonics Tools @ nanoHUB.org

Primary Contact: Jieran Fang
Additional Contact: Dr. Ludmila Prokopeva, Rohith Chandrasekar, Dr. Urcan Guler
Advisors: Prof. Alexander Kildishev, Prof. Vladimir Shalaev
Collaborators: Dr. Xingjie Ni, Dr. Satoshi Ishii, Dr. Zhengtong Liu, Dr. Uday. K. Chettiar, Jan Trieschmann

Short project description:

We developed simulation tools for nanophotonics, staged at www.nanoHUB.org to deliver a scientific application as a cloud computing service. Our on-line tools provide electromagnetic and multiphysics simulations of planar, circular and spherical multilayered nanophotonic devices, the full list is:

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Nanophotonics Tools @ nanoHUB.org
Nanophotonics Tools @ nanoHUB.org

Publications and other contributions:

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Novel Optics with Metasurfaces

Primary Contact: Amr Shaltout
Additional Contact: Jongbum Kim
Advisors: Prof. Vladimir Shalaev, Prof. Alexander Kildishev

Short project description:

Nanophotonics Tools @ nanoHUB.org

Subwavelength cavities are obtained by replacing conventional mirrors with reflecting metasurfaces that introduce arbitrary phase-shifts compensating for reduced accumulated phase through the ultra-small cavity. Same concept works for waveguides, where propagating modes require round trip phase-shift in the transverse direction to be integer multiple of 2p. This causes the minimum cross-section size to be the diffraction limit of ?/2, and introducing reflecting metasurfaces change the phase condition allowing the cross-section to go below the diffraction limit.

Nanophotonics Tools @ nanoHUB.org

We design, fabricate, and experimentally demonstrate optically active metasurfaces of ?/50 thickness. Our approach is built on supercell metasurface design methodology: by judiciously designing the location and orientation of individual antennas in the structural supercells, we achieve effective chiral metasurfaces through a collective operation of non-chiral antennas.

 
Nanophotonics Tools @ nanoHUB.org

Ultrathin metamaterial layers are modeled by a homogeneous bi-anisotropic film to model various kinds of broken symmetries in photonic nanostructures. It successfully modeled rotational asymmetry, mirror asymmetry and directional asymmetry. It has been also used to replace an array of nanostructured plasmonic elements (e.g. V-shape antennas) with a thin metasurface of equivalent bianisotropic tiles, which enabled significant reduction of computational load for simulation purposes.

Papers Published:

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Nanolasers

Primary Contact: Dr. Xiangeng Meng
Additional Contacts: Jingjing Liu, Jieran Fang, Zhuoxian Wang , Dr. Urcan Guler, Rohith Chandrasekar
Advisors: Prof. Vladimir Shalaev, Prof. Alexander Kildishev
Collaborators: Dr. Alexei S. Lagoutchev

Short project description:

The nanolaser project aims to develop compact light sources using plasmonic nanostructures as resonant cavities. The nanolaser is based on amplification of surface plasmons ? surface waves propagating along a metallic-dielectric interface, thus also entitled spaser (short for surface plasmon amplification by stimulated emission of radiation). The fact that plasmon modes have no cutoff allows for creation of compact light sources at real nanometer scale in terms of either the device size or optical mode volume. There are currently several challenges that are being addressed in this area, including the control of spasing propagation direction and the achievement of spasing in the visible. Numerical simulations are being conducted to help understanding of spasing dynamics.

Namolasers

Papers Published:

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Unlocking New Physics and Novel Applications using Nanowire-based Hyperbolic Metamaterials

Contact: Rohith Chandrasekar
Advisors: Dr. Xiangeng Meng, Prof. Alexander Kildishev, Prof. Vladimir Shalaev
Collaborators: Prof. Alexandra Boltasseva, Prof. Alexander Wei, Dr. Yantao Pang (Shandong Jianzhu University)

Short project description:

Hyperbolic metamaterials are a new class of metamaterials that exhibit hyperbolic dispersion, a characteristic that can be applied to achieve exciting phenomena such as subdiffraction imaging, radiative decay engineering, hyperlensing and single-photon sources, to name a few. Hyperbolic metamaterials can be fabricated using two geometries: (1) alternating metal and dielectric layers, or (2) growing metal nanowires in a dielectric host matrix.

In this project, we focus on fabricating highly-ordered, high-quality gold and silver nanowire arrays in an alumina matrix. The samples are grown directly on a glass substrate for ease in characterization and device implementation. Using these new materials, we are currently pushing forward on multiple efforts: (1) measuring lifetime enhancement of dyes and nanodiamonds placed on or embedded in nanowire arrays, (2) studying lasing characteristics of nanowire arrays embedded in laser dyes, and (3) fabricating curved nanowire structures for future studies in hyperlensing and subdiffraction imaging.

Nanowire_HMM

Papers Published:

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Second-Harmonic Generation with Plasmonic Metasurfaces

Primary Contact: Rohith Chandrasekar
Additional Contact: Naresh K. Emani
Advisors:Prof. Alexander Kildishev, Prof. Vladimir Shalaev
Collaborators: Prof. Alexandra Boltasseva; Dr. Alexei S. Lagoutchev, Prof. David R. Smith (Duke University), Dr. Cristian Ciraci (Duke University)

Short project description:

In this project, we would like to directly compare the enhancement provided by electric and magnetic resonances for second harmonic generation (SHG). We study SHG by a metasurface consisting of coupled silver nanostrips that exhibits both electric and magnetic resonance for TM-polarized light. We set the electric resonance at the second harmonic and the magnetic resonance at the fundamental. By tuning the magnetic resonance on and off the fundamental, we can study each resonance individually and study their combined effects. We find that the electric resonance provides twice the enhancement provided by magnetic resonance. We use simulations and fittings to show that SHG by magnetic resonance is inhomogeneously broadened due to its broad tunability.

Namolasers

Papers Published:

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Near field characterization of plasmonic nanostructures

Contact: Clayton DeVault
Additional contacts: Paul West, Alexei Lagoutchev
Advisors: Prof. Vladimir Shalaev, Prof. Alexandra Boltasseva

Short project description:

The ability to "see" at the nano-scale is enormously important to the fields of plasmonics and metamaterials. Although the ultimate spatial resolution of a far-field imaging system is limited by diffraction to roughly half the wavelength of the light source, there are several methods to circumnavigate this diffraction limit. Near-Field Scanning Optical Microscopy (NSOM) is a technique that allows resolution well below the natural restriction imposed by diffraction. This is accomplished by maintaining an optical fiber in extremely close proximity (a fraction of the wavelength) to a sample’s surface. At these distances, the optical probe interacts with non-propagating evanescent fields. The spatial resolution is then limited only by the size of the optical fiber’s aperture, which may be as small as 50nm. We utilize this technique to study structures such as nano-antennas, plasmonic waveguides, and metasurfaces. Our NSOM system is capable of operating in reflection, collection, and illumination modes at wavelengths of 532, 633, 785, and 1550 nm.

Near-Field_Characterization

Papers Published:

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Chemical synthesis of nanomaterials

Contact: Dr. Swati Pol
Advisors: Prof. Vladimir Shalaev, Prof. Alexandra Boltasseva

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Computer modeling of random plasmonic nanostructures

Contact: Jieran Fang
Advisors: Prof. Alexander Kildishev, Prof. Vladimir Shalaev

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