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.
J. Liu, U. Guler, A. Lagoutchev, A. Kildishev, O. Malis, A. Boltasseva, V. M. Shalaev, "Quasi-coherent thermal emitter based on refractory plasmonic materials", Opt. Mater. Express, submitted.
U. Guler, S. Suslov, A. V. Kildishev, A. Boltasseva, V. M. Shalaev, "Colloidal plasmonic titanium nitride nanoparticles: Properties and applications", Nanophotonics, DOI: 10.1515/nanoph-2015-0017 (*Invited Research Paper*).
U. Guler, A. Boltasseva, V. M. Shalaev, "Plasmonics on the slope of enlightenment: the role of transition metal nitrides", Faraday Discuss. 178, 71-86 (2015) (*Invited Research Paper*)
U. Guler, V. M. Shalaev, and A. Boltasseva, "Nanoparticle Plasmonics: Going Practical with Transition Metal Nitrides," Materials Today, 18, 227-237 (2015) (*Invited Review Paper*).
W. Li, U. Guler, N. Kinsey, G. V. Naik, A. Boltasseva, J. Guan, V. M. Shalaev, and A. V. Kildishev, "Refractory Plasmonics with Titanium Nitride: Broadband Metamaterial Absorber," Adv. Mater. 26, 7959-7965 (2014). (*Cover Article*)
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.
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.
M. Y. Shalaginov, G. V. Naik, S. Ishii, M. N. Slipchenko, A. Boltasseva, J.-X. Cheng, A. N. Smolyaninov, E. Kochman, and V. M. Shalaev. "Characterization of nanodiamonds for metamaterial applications," Appl.Phys.B 105, 2, 191-195 (2011)
M. Y. Shalaginov, S Ishii, J Liu, A Kildishev, VM Shalaev, "Broadband enhancement of spontaneous emission from nitrogen-vacancy centers in nanodiamonds by hyperbolic metamaterials" in 2013 Conference on Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), San Jose, CA, USA, 2013
M. Y. Shalaginov, S.Ishii, J. Liu, J. Liu, J. Irudayaraj, A. Lagutchev, A.V. Kildishev, and V. M. Shalaev, "Broadband enhancement of spontaneous emission from nitrogen-vacancy centers in nanodiamonds by hyperbolic metamaterials", Appl. Phys. Lett. 102, 173114 (2013)
M. Y. Shalaginov, V. V. Vorobyov, J. Liu, Marcello Ferrera, A. V. Akimov, A. Lagutchev, A. N. Smolyaninov, V. V. Klimov, J. Irudayaraj, A. V. Kildishev, A. Boltasseva and V. M. Shalaev, "Single-photon source based on NV center in nanodiamond coupled to TiN-based hyperbolic metamaterial" in 2014 Conference on Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), San Jose, CA, USA, 2014
M. Y. Shalaginov, V. V. Vorobyov, J. Liu, M. Ferrera, A. V. Akimov, A. Lagutchev, A. N. Smolyaninov, V. V. Klimov, J. Irudayaraj, A. V. Kildishev, A. Boltasseva, and V. M. Shalaev, "Enhancement of single-photon emission from nitrogen-vacancy centers with TiN/(Al,Sc)N hyperbolic metamaterials", Laser Photonics Rev., 9, 1, 120-127 (2015) (*Cover Article*)
M. Y. Shalaginov, A. Lagutchev, V. M. Shalaev, and A. V. Kildishev, "Effect of a hyperbolic metamaterial on radiation patterns of a single-photon source", in 2015 Conference on Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), San Jose, CA, USA, 2015
S. Bogdanov, M. Y. Shalaginov, A. Akimov, P. Kapitanova, J. Liu, D. Woods, M. Ferrera, A. S. Laguchev, P Belov, J. Irudayaraj, A. Boltasseva, and V. M. Shalaev, "Engineering the spin-flip induced fluorescence contrast of diamond nitrogen
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:
PhotonicsDB: approximating and comparing the frequency dispersive optical properties of various materials.
PhotonicsRT: designing planar nanostructured lamellar photonic crystals and non-reflecting coatings.
PhotonicsSHA-2D: user customized cascaded photonic or plasmonic 2D metamaterials.
Ludmila Prokopeva; You-Chia Chang; Alexander V. Kildishev (2015), "PhotonicVASEfit: VASE fitting tool," https://nanohub.org/resources/photonicvasefit. (DOI: 10.4231/D3JH3D373).
Rohith Chandrasekar; Urcan Guler; Ludmila Prokopeva; Alexander V. Kildishev (2015), "PhotonicsPOS: Particle on Substrate," https://nanohub.org/resources/photonicspos. (DOI: 10.4231/D3S756M23).
J. Fang, J. Liu, Z. Wang, X. Meng, L. Prokopeva, V. M. Shalaev, and A. V. Kildishev, "Time-Domain Model of 4-Level Gain System Fitted to Nanohole Array Lasing Experiment," in CLEO: 2015, OSA Technical Digest (online) (Optical Society of America, 2015), paper FW3E.5.
J. Fang; L. Prokopeva; J. Trieschmann; N. Arnold; A. V. Kildishev (2013), "PhotonicsGAIN-0D," http://nanohub.org/resources/testgain0d. (DOI: 10.4231/D3PK07200)
Satoshi Ishii; Uday K. Chettiar; Xingjie Ni; Alexander V. Kildishev (2012), "PhotonicsRT: Wave Propagation in Multilayer Structures," https://nanohub.org/resources/photonicsrt. (DOI: 10.4231/D3BG2H902).
Xingjie Ni; Zhengtong Liu; Fan Gu; Marcos Gabriel Pacheco; Joshua Borneman; Alexander V. Kildishev (2012), "PhotonicsSHA-2D: Modeling of Single-Period Multilayer Optical Gratings and Metamaterials," https://nanohub.org/resources/sha2d. (DOI: 10.4231/D3WS8HK4X).
J. Trieschmann, S. Xiao, L. J. Prokopeva, V. P. Drachev, and A. V. Kildishev, "Experimental retrieval of the kinetic parameters of a dye in a solid film" Optics Express, Vol. 19, Issue 19, 18253-18259 (2011)
Xingjie Ni; Fan Gu; Ludmila Prokopeva; Alexander V. Kildishev (2011), "PhotonicsCL: Photonic Cylindrical Multilayer Lenses," https://nanohub.org/resources/photonicscl. (DOI: 10.4231/D3Q52FC6B).
Xingjie Ni; Zhengtong Liu; Alexander V. Kildishev (2010), "PhotonicsDB: Optical Constants," https://nanohub.org/resources/PhotonicsDB. (DOI: 10.4231/D3FT8DJ4J).
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.
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.
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.
A. M. Shaltout, A. V. Kildishev, and V. M. Shalaev "Ultra-Small Cavity with Reflecting Metasurfaces", US patent application.
A. M. Shaltout, A. V. Kildishev, V. M. Shalaev, "Compact Subwavelength Cavities Using Reflecting Metasurfaces," Accepted for 2014 Conference on Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), San Jose, CA, USA, 2014.
A. M. Shaltout, V. M. Shalaev , and A. V. Kildishev "Waveguides with Hyperbolic Metasurface Claddings", ACES 2014 Conference, Jacksonsville, Fl, USA, 2014. (4th place winner of student paper competition)
P.R. West, J. L. Stewart, A. Kildishev, V.M. Shalaev, V. Shkunov, F. Strohkendl, Y. Zakharenkov, R. Dodds, R. Byren, "All-dielectric subwavelength metasurface focusing lens," submitted to Optics Express, 2014.
A. M. Shaltout, J. Liu, V. M. Shalaev, and A. V. Kildishev, "Optically Active Metasurfaces with Nonchiral Plasmonic Nano-antennas" submitted for journal publication.
F. Ding, N. Kinsey, J. J. Liu, Z. X. Wang; V. M. Shalaev and A. V. Kildishev, "Unidirectional Surface Plasmon Polariton Coupler in the Visible Using Metasurfaces," Accepted for 2014 Conference on Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), San Jose, CA, USA, 2014.
J. Liu, A. M. Shaltout, X. Ni, V. M. Shalaev, and A. V. Kildishev, "Approximating metasurfaces with bianisotropic tiles" ACES 2014 Conference (Invited paper), Jacksonsville, Fl, USA, 2014.
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.
X. Meng, U. Guler, A. V. Kildishev, K. Fujita, K. Tanaka, and V. M. Shalaev, "Unidirectional Spaser in Symmetry-Broken Core-Shell Nanocavity", Sci. Rep. 3, 1241 (2013).
X. Meng, A. V. Kildishev, K. Fujita, K. Tanaka, and V. M. Shalaev, "Wavelength-Tunable Spasing in the Visible", Nano Lett. 13, 4106-4112 (2013).
X. Meng, J. Liu, A. V. Kildishev, and V. M. Shalaev, "Highly Directional Spaser Array for the Red Wavelength Region", Laser Photonics Rev. 8, 896-903 (2014).
J. Fang; L. Prokopeva; J. Trieschmann; N. Arnold; A. V. Kildishev, "PhotonicsGAIN-0D," DOI: 10.4231/D3PK07200, (2013)
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.
Y. Pang, R. Chandrasekar, "Cylindrical and spherical membranes of anodic aluminium oxide with highly ordered conical nanohole arrays" Natural Science 7, 232-237 (2015)
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.
R. Chandrasekar, N. K. Emani, A. Lagutchev, V.M. Shalaev, A.V. Kildishev, C. Ciraci, and D.R. Smith, "Second Harmonic Generation by Metamagnetics: Interplay of Electric and Magnetic Resonances" Frontiers in Optics 2014
R. Chandrasekar, N. K. Emani, A. Lagutchev, V.M. Shalaev, C. Ciraci, D.R. Smith, and A.V. Kildishev, "Studying the Interplay of Electric and Magnetic Resonance-Enhanced Second Harmonic Generation: Theory and Experiments" CLEO/QELS 2015, San Jose CA.
R. Chandrasekar, N. K. Emani, A. Lagutchev, V.M. Shalaev, C. Ciraci, D.R. Smith, and A.V. Kildishev, "Second Harmonic Generation by Plasmonic Metasurfaces: Direct Comparison of Electric and Magnetic Resonances" (Submitted to Optical Materials Express Special Optics on Plasmonics)
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.
M. D. Thoreson, R. B. Nielsen, P. R. West, A. Kriesch, Z. Liu, J. Fang, A. V. Kildishev, U. Peschel, V. M. Shalaev, A. Boltasseva, Studies of plasmonic hot-spot translation by a metal-dielectric layered superlens, Proc. SPIE, 2011.
DReuben M Bakker, Vladimir P Drachev, Zhengtong Liu, Hsiao-Kuan Yuan, Rasmus H Pedersen, Alexandra Boltasseva, Jiji Chen, Joseph Irudayaraj, Alexander V Kildishev and Vladimir M Shalaev, Nanoantenna array-induced fluorescence enhancement and reduced lifetimes, New Journal of Physics 10, 125022 (2008).
Reuben M. Bakker, Hsiao-Kuan Yuan, Zhengtong Liu, Vladimir P. Drachev, Alexander V. Kildishev, Vladimir M. Shalaev, Rasmus H. Pedersen, Samuel Gresillon, Alexandra Boltasseva, Enhanced localized fluorescence in plasmonic nanoantennae, Appl. Phys. Lett. 92, 043101 (2008)
Reuben M. Bakker, Alexandra Boltasseva, Zhengtong Liu, Rasmus H. Pedersen, Samuel Gresillon, Alexander V. Kildishev, Vladimir P. Drachev, and Vladimir M. Shalaev, Near-field excitation of nanoantenna resonance, Optics Express, Vol. 15, Issue 21, pp. 13682-13688 (2007)
R.M. Bakker, V.P. Drachev, H.-K. Yuan, and V.M. Shalaev, Enhanced transmission in near-field imaging of layered plasmonic structures, Optics Express, v. 12, #16, pp. 3701-3706 (2004)