Viktor Podolskiy

University of Massachusetts Lowell | UML · Department of Physics and Applied Physics

We demonstrate, experimentally and theoretically, a new class of angle-insensitive band-pass optical filters that utilize anisotropy of plasmonic nanorod metamaterials, in both ε ≃ -1 and epsilon-near-infinity regimes, to minimize dependence of optical path on the incident angle. The operating wavelength and bandwidth of the filter can be engineere...

Hyperbolic metamaterials were initially proposed in optics to boost radiation efficiencies of quantum emitters. Adopting this concept for antenna design allows approaching long-standing contests in radio physics. For example, broadband impedance matching, accompanied with moderately high antenna gain, is among the existent challenges. Here we propo...

The control of spontaneous emission via the design of composite materials with engineered electromagnetic properties is important for the development of new faster and brighter sources of illumination with applications ranging from biophysics to quantum optical technologies. In particular, the fabrication of nanostructures leading to broadband enha...

Pixel size in cameras and other refractive imaging devices is typically limited by the free-space diffraction. However, a vast majority of semiconductor-based detectors are based on materials with substantially high refractive index. We demonstrate that diffractive optics can be used to take advantage of this high refractive index to reduce effecti...

Nonlinear processes are at the core of many optical technologies including lasers, information processing, sensing, and security, and require optimised materials suitable for nanoscale integration. Here we demonstrate the emergence of a strong bulk second-order nonlinear response in a composite plasmonic nanorod material comprised of centrosymmetri...

Recent successes in fabrication, characterization, numerical computations, and theory have brought to life a new class of composite materials with engineered optical properties, metamaterials. Uniaxial anisotropic artificially created structures based on plasmonic nanowire arrays have emerged as a versatile platform for negative refraction, subwave...

Light-matter interactions at a particular point in a material may be dominated by properties of the medium at this point or they could be affected by the electromagnetic properties of the medium in the surrounding regions. In the former case, the medium is said to be local, while in the latter, it is nonlocal. Recent studies of light-matter interac...

We demonstrate strong, narrow-band selective absorption and subsequent selective thermal emission from ultra-thin planar films of polar materials at mid-infrared wavelengths. Our structures consist of AlN layers of varying thicknesses deposited upon molybdenum ground planes. We demonstrate coupling to the Berreman mode at frequencies at, or near, t...

Hot carrier dynamics in plasmonic nanorod metamaterials and its influence on the metamaterial's optical Kerr nonlinearity is studied. The electron temperature distribution induced by an optical pump in the metallic component of the plasmonic metamaterial leads to geometry-dependent variations of the optical response and its dynamics as observed in...

A typo in the software implementation of Diffractive Interface Theory [Opt. Express23, 2764 (2015)10.1364/OE.23.002764] was found during subsequent research. The typo was corrected, yielding better-than-originally-reported agreement between Diffractive Interface Theory and full-wave numerical solutions of Maxwell equations.

Strong coupling of excitons in macroscopic ensembles of quantum emitters and cavities (or surface plasmons) can lead to dramatic change of the optical properties and modification of the dispersion curves, characterized by the normal mode splitting of the order of 1 eV. Such gigantic alteration of the hybrid energy states enables scores of unparalle...

We consider the problem of light transmission from a high refractive index medium into a low index environment. While total internal reflection severely limits such transmission in systems with smooth interfaces, diffractive metasurfaces may help out-couple light that enters an interface at blazing angles. We demonstrate that the profile of the str...

We present a new formalism for understanding the optical properties of metasurfaces, optically thin composite diffractive devices. The proposed technique, Rigorous Diffraction Interface Theory (R-DIT), provides an analytical framework for understanding the transition between optically thin and optically thick structures. For metasurfaces, R-DIT avo...

Fluorescence-based processes are strongly modified by the electromagnetic environment in which the emitters are placed. Hence, the design of nanostructured materials with appropriate electromagnetic properties opens up a new route in the control of, for instance, the spontaneous rate of emission or the energy transfer rate in donor-acceptor pairs....

Light-matter interactions can be dramatically modified by the surrounding environment. Here we report on the first experimental observation of molecular spontaneous emission inside a highly nonlocal metamaterial based on a plasmonic nanorod assembly. We show that the emission process is dominated not only by the topology of its local effective medi...

There has been recent interest in the development of optical analogues of lumped element circuitry, where optical elements act as effective optical inductors, capacitors, and resistors. Such optical circuitry requires the photonic equivalent of electrical wires, structures able to carry optical frequency signals to and from the lumped circuit eleme...

We present an analytical description and an experimental realization of interscale mixing microscopy, a diffraction-based imaging technique that is capable of detecting wavelength/10 objects in far-field measurements with both coherent and incoherent broadband light. This method aims at recovering the spatial spectrum of light diffracted by a subwa...

There has been recent interest in the development of optical analogues of lumped element circuitry, where optical elements act as effective optical inductors, capacitors, and resistors. Such optical circuitry requires the photonic equivalent of electrical wires, structures able carry optical frequency signals to and from the lumped circuit elements...

We analyze the optical properties of composite materials that combine nanowire and nanolayer platforms. We revisit effective-medium theory (EMT) description of wire materials with high filling fraction positioned in anisotropic unit cells and present a simple numerical technique to extend Maxwell–Garnett formalism in this limit. We also demonstrate...

Computationally designed multi-scale gratings demonstrating both diffractive and effective medium properties can dramatically increase optical coupling out of a high-index dielectric. Typical results show increase of transmission on the order of 20%.

Metallic films with subwavelength apertures integrated into a semiconductor exhibit broadband enhancement of light coupling into the semiconductor (compared to an unstructured surface) while providing near uniform electrical contact for potential integration into optoelectronic devices.

Metallic films with subwavelength apertures, integrated into a semiconductor by metal-assisted chemical etch (MacEtch), demonstrate enhanced transmission when compared to bare semiconductor surfaces. The resulting "buried" metallic structures are characterized spectroscopically and modeled using rigorous coupled wave analysis. These composite mater...

The radiation dynamics of optical emitters can be manipulated by properly designed material structures modifying local density of photonic states, a phenomenon often referred to as the Purcell effect. Plasmonic nanorod metamaterials with hyperbolic dispersion of electromagnetic modes are believed to deliver a significant Purcell enhancement with bo...

In Extraordinary Optical Transmission (EOT), a metallic film perforated with an array of [periodic] apertures exhibits transmission over 100% normalized to the total aperture area, at selected frequencies. EOT devices have potential applications as optical filters and as couplers in hybrid electro-optic contacts/devices. Traditional passive extraor...

Plasmonic metamaterial composites are often considered to be promising building blocks for a number of applications that include subwavelength light manipulation, imaging, and quantum optics engineering. These applications often rely on effective medium response of metamaterial composites and require metamaterial to operate in exotic (hyperbolic, o...

Metamaterials with hyperbolic dispersion based on metallic nanorod arrays provide a flexible platform for the design of bio- and chemical sensors and nonlinear devices, allowing the incorporation of functional materials into and onto the plasmonic metamaterial. Here, we have investigated, both analytically and numerically, the dependence of the opt...

We analyze, analytically and computationally, light emission in nonlocal plasmonic nanowire metamaterials and analyze the contribution of longitudinal wave to the density of optical states in the system.

We present a novel formalism to describe diffractive optics of metasurfaces, diffractive interface theory (DIT).

The radiation dynamics of optical emitters can be manipulated by properly designed material structures providing high local density of photonic states, a phenomenon often referred to as the Purcell effect. Plasmonic nanorod metamaterials with hyperbolic dispersion of electromagnetic modes are believed to deliver a significant Purcell enhancement wi...

We demonstrate that the incorporation of nonlocal nanowire metamaterials into Salisbury screens allows for a substantial reduction of the dependence of incident angle on the absorption maximum. Realizations of angle-independent Salisbury screens for the near-IR, mid-IR, and GHz frequencies are proposed and their performances are analyzed analytical...

We present analytical and computational studies of light emission in nonlocal metamaterials formed by arrays of aligned plasmonic nanowires. We demonstrate that emission lifetime in these composites is a complex function of geometrical and material parameters of the system that cannot be reduced to “trivial” hyperbolic or elliptical dispersion topo...

We present a formalism for understanding the elecromagnetism of metasurfaces, optically thin composite films with engineered diffraction. The technique, diffractive interface theory (DIT), takes explicit advantage of the small optical thickness of a metasurface, eliminating the need for solving for light propagation inside the film and providing a...

We analyze, analytically and numerically, optical properties of plasmonic nanowire composites that form a promising platform for nanophotonics, present description of nonlocal electromagnetism in this media, and discuss implications of nonlocal response for different applications.

We present an imaging technique that allows the recovery of the transparency profile of wavelength-scale objects with deep subwavelength resolution based on far-field intensity measurements. The approach, interscale mixing microscopy (IMM), relies on diffractive element positioned in the near-field proximity to the object, to scatter information ca...

We demonstrate that nonlocal nanowire metamaterials can help to alleviate one of the main limitations of Salisbury screens, their dependence on the incident angle.

We present numerically stable expansion basis for diffraction-based far-field computational imaging systems and demonstrate the capabilities of reconstructing wavelength-scale objects with wavelength/20 resolution.

We have extensively investigated heavily doped semiconductors as potential plasmonic metals at long wavelengths. The ability to control the doping level in a semiconductor material, both III-V's (InAs/InSb) and Silicon, allows for control of the metal's optical properties, and adds an intriguing additional controllable parameter to the design of pl...

Having in mind parametric amplification of surface plasmon polaritons (SPPs) as the final goal, we took the first step and studied in the Kretschmann geometry a simpler nonlinear optical process - second harmonic generation (SHG) enhanced by SPPs propagating at the interface between gold film and 2-methyl-4-nitroaniline (MNA). The experimentally de...

We demonstrate excitation of surface phonon polaritons on patterned gallium phosphide surfaces. Control over the light-polariton coupling frequencies is demonstrated by changing the pattern periodicity and used to experimentally determine the gallium phosphide surface phonon polariton dispersion curve. Selective emission via out-coupling of thermal...

We investigate the utility of heavily doped semiconductors as plasmonic materials for mid-IR applications. The wavelength flexibility and design-ability of these materials allow for the demonstration of nanophotonic structures and devices for long-wavelength IR light.

We present a comprehensive analysis of the role of ε-near-zero (ENZ) materials with realistic losses in enhanced light transmission through subwavelength channels. In this work, we utilize a bulk ENZ material consisting of heavily doped semiconductor, operating at the semiconductor's plasma frequency (in mid-infrared regime). Resonant transmission...

We demonstrate epitaxially grown all-semiconductor thin-film midinfrared plasmonic absorbers and show that absorption in these structures is linked to the excitation of highly confined negative-index surface plasmon polaritons. Strong (>98%) absorption is experimentally observed, and the spectral position and intensity of the absorption resonances...

We present an analytical description of the nonlocal optical response of plasmonic nanowire metamaterials that enable negative refraction, subwavelength light manipulation, and emission lifetime engineering. We show that dispersion of optical waves propagating in nanowire media results from coupling of transverse and longitudinal electromagnetic mo...

We propose optical imaging technique that relies on diffractive rather than refractive elements. Our approach takes advantage of metagratings, structures with engineered diffraction properties, and natural materials with sufficiently high refractive indices to achieve significant reduction in pixel size. In contrast to conventional refraction-based...

This special issue presents a cross-section of recent progress in the rapidly developing area of optics of hyperbolic metamaterials.

The hyperbolic and plasmonic properties of silicon nanowire/Ag arrays have been investigated. The aligned nanowire arrays were formed and coated by atomic layer deposition of Ag, which itself is a metamaterial due to its unique mosaic film structure. The theoretical and numerical studies suggest that the fabricated arrays have hyperbolic dispersion...

Hyperbolic materials enable numerous surprising applications that include far-field subwavelength imaging, nanolithography, and emission engineering. The wavevector of a plane wave in these media follows the surface of a hyperboloid in contrast to an ellipsoid for conventional anisotropic dielectric. The consequences of hyperbolic dispersion were f...

We demonstrate a mid-infrared perfect absorber fabricated only from highly-doped semiconductors. A strong (>98%) absorption resonance is observed which is effectively independent of lateral geometry, but highly dependent on the vertical profile.

We present a diffraction-based computational imaging paradigm and illustrate its applications for a highly-compact imaging systems capable of 3D imaging with 2D sensors.

Optical sensors for ultrasound detection provide high sensitivity and bandwidth, essential for photoacoustic imaging in clinical diagnostics and biomedical research. Implementing plasmonic metamaterials in a non-resonant regime facilitates sub-nanosecond, highly sensitive detectors while eliminating cumbersome optical alignment necessary for resona...

We report measurements of near-field absorption in heavily silicon-doped indium arsenide microparticles using atomic force microscope infrared spectroscopy (AFM-IR). The microparticles exhibit an infrared absorption peak at 5.75 μm, which corresponds to a localized surface plasmon resonance within the microparticles. The near-field absorption measu...

Surface plasmon polaritons and their localized counterparts, surface plasmons, are widely used at visible and near-infrared (near-IR) frequencies to confine, enhance, and manipulate light on the subwavelength scale. At these frequencies, surface plasmons serve as enabling mechanisms for future on-chip communications architectures, high-performance...

Nanowire metamaterials are a class of materials formed by an array of aligned plasmonic nanowires embedded in a dielectric host which exhibit strongly anisotropic behavior. For a wide range of excitation frequencies, the optical properties of these systems are dominated by two waves with different polarizations. In contrast to this behavior, in the...

Recent developments in semiconductor technology brought to life a new generation of highly-compact visible-frequency cameras. Unfortunately, straight forward extension of this progress to low-frequency domains (such as mid-IR imaging) is impossible since the pixel size at these frequencies is limited by free-space diffraction limit. Here we present...

Here we demonstrate a new class of designer plasmonic materials for use in the mid-infrared (mid-IR) region of the electromagnetic spectrum. By heavily doping epitaxially-grown semiconductor materials, we are able to grow single-crystal materials whose optical properties in the mid-IR mimic those of metals at shorter wavelengths. We demonstrate mat...

We present a diffraction-based imaging paradigm and illustrate its applications for subwavelength imaging and for implementation of highly-compact imaging sensors capable of dynamic refocusing of optical images

We demonstrate reduced reflectance and a corresponding enhancement of transmittance in lamellar hyperbolic metamaterials, with scatterers deposited on the top. The effect is much more significant in curvilinear hyperbolic metamaterials. We also show that absorption strengths of dyes on the top of hyperbolic metamaterials can be tuned and enhanced (...

We demonstrate time-resolved terahertz transmission ellipsometry of vertically aligned multi-walled carbon nanotubes. The angle-resolved transmission measurements reveal anisotropic characteristics of the terahertz electrodynamics in multi-walled carbon nanotubes. The anisotropy is, however, unexpectedly weak: the ratio of the tube-axis conductivit...

We demonstrate that homogeneous naturally-occurring materials can form hyperbolic media, and can be used for nonmagnetic negative refractive index systems. We present specific realizations of the proposed approach for the THz and far-IR frequencies. The proposed structures operate away from resonance, thereby promising the capacity for low-loss dev...

We demonstrate reduced reflectance in curvilinear lamellar hyperbolic metamaterials as well as planar hyperbolic metamaterials consisting of metal/dielectric multilayers, with scatterers deposited on the top. The reduced reflectance is accompanied by a significant enhancement in transmission along with non-reciprocity of transmittance in forward an...

We analyze the propagation of electromagnetic modes guided by periodic plasmonic structures. We use full-wave solutions of Maxwell equations to calculate dispersion of these modes and derive analytical description of their optical properties. Finally, we demonstrate that, at a certain frequency range that can be controlled by the geometry, diffract...

THz ellipsometry with broadband THz pulses reveals anisotropic THz responses from closely packed, vertically grown CNTs. Non-negligible conductivity in a direction normal to the CNT axis indicates carrier transport between adjacent CNTs.

We present detailed description of a computer method for the calculation of the conductivity of inhomogeneous systems based on an exact renormalization group transformation. We study by this method the effective conductivity of the three-dimensional resistor network at the percolation threshold. For lattices ranging in size from 43 to 1403 we measu...

Plasmonic structures, with periodic arrays of thin PMMA ridges on metal substrates have been shown experimentally to overcome the diffraction limit. Here we present a theoretical description of this phenomenon. We use mode matching technique to analyze the dynamics of the electromagnetic waves in the periodic systems, taking into account the extend...

We demonstrate that homogeneous naturally-occurring materials can form non-magnetic negative refractive index systems, and present specific realizations of the proposed approach for the THz and far-IR frequencies. The proposed structure operates away from resonance, thereby promising the capacity for low-loss devices.

We demonstrate strong coupling between a mid-infrared perfect absorber and a molecular absorption resonance embedded in our absorber structure. Anti-crossing behavior is demonstrated as the perfect absorber resonance is tuned through the molecular absorption line, both experimentally and numerically, and is described analytically using a simple cou...

THz ellipsometry with broadband THz pulses reveals anisotropic THz responses from closely packed, vertically grown CNTs. Non-negligible conductivity in a direction normal to the CNT axis indicates carrier transport between adjacent CNTs.

We present numerical and analytical studies of the nonlocal optical response for plasmonic nanorod metamaterials. Dispersion of photonic modes has been studied and an analytical description of the nonlocal effective permittivity has been developed.

We present a numerical analysis of low diffracting states in plasmonic crystals formed by PMMA guides on Au substrate and develop an analytical description of this phenomenon.

We demonstrate excitation of additional electromagnetic waves in plasmonic nanorod metamaterials. These waves arising from a nonlocal optical response of metamaterial results in strongly enhanced ultrafast nonlinear response.

Preface to a focus issue of invited articles that review recent progress in studying the fundamental physics of collective phenomena associated with coupling of confined photonic, plasmonic, electronic and phononic states and in exploiting these phenomena to engineer novel devices for light generation, optical sensing, and information processing.

We present a comprehensive study of enhanced light funneling through a subwavelength aperture with realistic (lossy) epsilon-near-zero (ENZ) materials. We realize experimentally an inclusion-free ENZ material layer operating at optical frequencies and characterize its performance. An analytical expression describing light funneling through several...