J.A. Bossard

Pennsylvania State University, State College, PA, United States

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Publications (55)97.87 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Nanostructured optical coatings with tailored spectral absorption properties are of interest for a wide range of applications such as spectroscopy, emissivity control, and solar energy harvesting. Optical metamaterial absorbers have been demonstrated with a variety of customized single band, multiple band, polarization, and angular configurations. However, metamaterials that provide near unity ab-sorptivity with super-octave bandwidth over a specified optical wavelength range have not yet been demonstrated experimentally. Here, we show a broadband, polarization-insensitive metamaterial with greater than 98% measured average absorptivity that is maintained over a wide ±45º field-of-view for mid-infrared wavelengths between 1.77 and 4.81 µm. The nearly ideal absorption is realized by using a genetic algorithm to identify the geometry of a single-layer metal nanostructure array that excites multiple overlapping electric resonances with high optical loss across greater than an octave band-width. The response is optimized by substituting palladium for gold to increase the infrared metallic loss and by introducing a dielectric superstrate to suppress reflection over the entire band. This demonstration advances the state-of-the-art in high-performance broadband metamaterial absorbers that can be reliably fabricated using a single patterned layer of metal nanostructures.
    ACS Nano 01/2014; · 12.06 Impact Factor
  • Zhi Hao Jiang, Lan Lin, Jeremy A Bossard, Douglas H Werner
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    ABSTRACT: In this work, we present the design, numerical experiments, and analysis of a plasmonic metamaterial thin film based on subwavelength nano-notch loaded modified fishnet structures. The resulting device offers a simultaneous bandpass filtering functionality with a broad enhanced optical transmission window and a gapless negative-zero-positive index transition to enable polarization-independent passive beam-steering. This unique characteristic is made possible by the introduced subwavelength nano-notches, which provide fine tuning and hybridization of the external and internal surface plasmon polariton modes. This allows tailoring of the dispersive properties of the plasmonic metamaterial for broadband operation. Specifically, a multilayer nanostructured modified fishnet with feature sizes accessible by modern nanofabrication techniques is presented, exhibiting a broad passband at the mid-infrared wavelengths from 3.0 to 3.7 µm and stopbands elsewhere in the 2.5 ~4.5 µm window. The transmittance normalized to area is around 3 dB within the broad 20% bandwidth of the passband. Additionally, the effective index undergoes a smooth transition from negative unity through zero to positive unity with low loss within the passband. The physical mechanism and the angular dispersion of the metamaterial are analyzed in detail. Finally, full-wave simulations of a prism formed from this metamaterial are performed to demonstrate that the proposed structure achieves simultaneous polarization-insensitive passive beam-steering and filtering functionalities.
    Optics Express 12/2013; 21(25):31492-505. · 3.55 Impact Factor
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    ABSTRACT: A new type of nature-inspired global optimization methodology based on atmospheric motion is introduced. The proposed Wind Driven Optimization (WDO) technique is a population based iterative heuristic global optimization algorithm for multi-dimensional and multi-modal problems with the potential to implement constraints on the search domain. At its core, a population of infinitesimally small air parcels navigates over an N-dimensional search space following Newton's second law of motion, which is also used to describe the motion of air parcels within the earth's atmosphere. Compared to similar particle based algorithms, WDO employs additional terms in the velocity update equation (e.g., gravitation and Coriolis forces), providing robustness and extra degrees of freedom to fine tune. Along with the theory and terminology of WDO, a numerical study for tuning the WDO parameters is presented. WDO is further applied to three electromagnetics optimization problems, including the synthesis of a linear antenna array, a double-sided artificial magnetic conductor for WiFi applications, and an E-shaped microstrip patch antenna. These examples suggest that WDO can, in some cases, out-perform other well-known techniques such as Particle Swarm Optimization (PSO), Genetic Algorithm (GA) or Differential Evolution (DE) and that WDO is well-suited for problems with both discrete and continuous-valued parameters.
    IEEE Transactions on Antennas and Propagation 05/2013; 61(5):2745-2757. · 2.33 Impact Factor
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    ABSTRACT: Metamaterials have the potential to create optical devices with new and diverse functionalities based on novel wave phenomena. Most practical optical systems require that the device properties be tightly controlled over a broad wavelength range. However, optical metamaterials are inherently dispersive, which limits operational bandwidths and leads to high absorption losses. Here, we show that deep-subwavelength inclusions can controllably tailor the dispersive properties of an established metamaterial structure thereby producing a broadband low-loss optical device with a desired response. We experimentally verify this by optimizing an array of nano-notch inclusions, which perturb the mode patterns and strength of the primary and secondary fishnet nanostructure resonances and give an optically thin mid-wave-infrared filter with a broad transmissive pass-band and near-constant group delay. This work outlines a powerful new strategy for realizing a wide range of broadband optical devices that exploit the unique properties of metamaterials.
    Scientific Reports 03/2013; 3:1571. · 2.93 Impact Factor
  • Jeremy A Bossard, Douglas H Werner
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    ABSTRACT: Metamaterials have been previously studied for their ability to tailor the dispersive IR emissivity of a surface. Here, we investigate two metamaterial structures based on an electromagnetic band-gap surface and a dielectric resonator array for use as near-IR emitters with custom angle selectivity. A genetic algorithm is successfully employed to optimize the metamaterial structures to have minimum emissivity in the normal direction and high emissivity at custom off-normal angles specified by the designer. Two symmetry conditions are utilized to achieve emissivity patterns that are azimuthally stable or distinct in the two orthogonal plane cuts.
    Optics Express 03/2013; 21(5):5215-5225. · 3.55 Impact Factor
  • Jeremy A Bossard, Douglas H Werner
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    ABSTRACT: Metamaterials have been previously studied for their ability to tailor the dispersive infrared (IR) emissivity of a surface. Here, we investigate metamaterial coatings based on an electromagnetic band-gap surface for use as near-IR emitters with custom polarization selectivity. A genetic algorithm is successfully employed to optimize the metamaterial structures to exhibit custom linear, circular, and elliptical polarization. A study is also conducted on a bi-anisotropic slab, showing that anisotropic chirality is required in the metamaterial structure in order to achieve circular or elliptical emissivity polarization.
    Optics Express 02/2013; 21(3):3872-3884. · 3.55 Impact Factor
  • J.A. Bossard, D.H. Werner
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    ABSTRACT: Metamaterials have been previously studied for their ability to tailor the dispersive IR emissivity of a surface. Here, we investigate a metamaterial structure based on an electromagnetic band-gap surface for use as near-IR emitters with custom polarization selectivity. A genetic algorithm is successfully employed to optimize a metamaterial structure to exhibit maximum circularly polarized emissivity in the normal direction.
    Antennas and Propagation Society International Symposium (APSURSI), 2012 IEEE; 01/2012
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    ABSTRACT: A parallelized real-valued clonal selection algorithm (CLONALG) is successfully implemented in this paper utilizing message passing interface (MPI) to reduce the computational burden of a large clone pool. CLONALG is one of the many branches of Artificial Immune System (AIS) algorithms with unique inherent properties that make it a very efficient optimization techniques for multimodal problems such as the ones commonly encountered in computational electromagnetic design. As a demonstration of its effectiveness, a numerical study is carried out with known benchmark functions along with the optimization of multi-layered frequency selective surface (FSS) filters in the X-band. Our results show that the CLONALG can consistently outperform a standard GA implementation particularly in multi-modal optimization problems.
    IEEE Transactions on Antennas and Propagation 01/2012; 60(4):1831-1843. · 2.33 Impact Factor
  • J.A. Bossard, Z. Bayraktar, D.H. Werner
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    ABSTRACT: Infrared (IR) absorbers have been previously studied for use in narrow-band and multi-band applications. Here, we investigate a broadband absorber structure comprised of multiple, stacked frequency selective surface screens. A genetic algorithm is successfully employed to optimize a structure with three Au screens to exhibit high absorptivity across the mid-IR range from 3 μm to 5 μm.
    Antennas and Propagation Society International Symposium (APSURSI), 2012 IEEE; 01/2012
  • J.A. Bossard, D.H. Werner
    [show abstract] [hide abstract]
    ABSTRACT: Metamaterials have been previously studied for their ability to tailor the dispersive IR emissivity of a surface. Here, we investigate two metamaterial structures based on an electromagnetic band-gap surface and dielectric resonators for use as near-IR emitters with custom angle selectivity. A genetic algorithm is successfully employed to optimize the metamaterial structures to have minimum emissivity in the normal direction and high emissivity at desired off-normal angles specified by the designer.
    Antennas and Propagation Society International Symposium (APSURSI), 2012 IEEE; 01/2012
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    ABSTRACT: This paper discusses the use of chalcogenide phase change materials to create tunable metamaterials as potential candidates for application to adaptive coded aperture control in the infrared. Phase change materials exhibit large and reversible changes in optical properties (Deltan, Deltak) when switched between the amorphous and crystalline phases. Thermally-induced phase transitions from the insulating amorphous to the conductive crystalline state can be controlled through external means, facilitating the design of reconfigurable metamaterial devices that operate with ultrafast response times. In this work, robust global stochastic optimization algorithms were combined with full-wave electromagnetic simulation tools to design periodic subwavelength chalcogenide nanostructured arrays to meet the specified device performance goals in each phase. The measured optical properties (n, k) of deposited chalcogenide thin films and nanofabrication constraints were incorporated into the optimization algorithm to guarantee that the designed nanostructures could be manufactured. By choosing the appropriate cost functions, adaptive metamaterials were designed to switch between transmissive and reflective, transmissive and absorptive, and reflective and absorptive states. These design demonstrations represent a significant step forward in the development of adaptive infrared metamaterials.
    Proc SPIE 09/2011;
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    ABSTRACT: Metamaterials provide an unprecedented ability to manipulate electromagnetic waves and are an enabling technology for new devices ranging from flat lenses that focus light beyond the diffraction limit to coatings capable of cloaking an object. Nevertheless, narrow bandwidths and high intrinsic losses arising from the resonant properties of metamaterials have raised doubts about their usefulness. New design approaches seek to turn the perceived disadvantages of dispersion into assets that enhance a device’s performance. Here we employ dispersion engineering of metamaterial properties to enable specific device performance over usable bandwidths. In particular, we design metamaterials that considerably improve conventional horn antennas over greater than an octave bandwidth with negligible loss and advance the state of the art in the process. Fabrication and measurement of a metahorn confirm its broadband, low-loss performance. This example illustrates the power of clever implementation combined with dispersion engineering to bring metamaterials into their full potential for revolutionizing practical devices.
    Nature Material 03/2011; 10(3):252. · 35.75 Impact Factor
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    ABSTRACT: In this paper, we present a method to retrieve the effective electromagnetic parameters of a slab of anisotropic metamaterial from reflection and transmission coefficients (or scattering parameters). In this retrieval method, calculated or measured scattering parameters are employed for plane waves incident obliquely on a metamaterial slab at different angles. Useful analytical expressions are derived for extracting the homogeneous anisotropic medium parameters of a metamaterial. To validate the method, the effective permittivity and permeability tensor parameters for a composite split-ring resonator-wire array are retrieved and shown to be consistent with observations previously reported in the literature. This retrieval method is further incorporated into a genetic algorithm (GA) to synthesize an infrared zero-index-metamaterial with a wide field-of-view, demonstrating the utility of the new design approach. The anisotropic parameter retrieval algorithm, when combined with a robust optimizer such as GA, can provide a powerful design tool for exploiting the anisotropic properties in metamaterials to achieve specific angle dependant or independent responses.
    Journal of Applied Physics 01/2011; 109(1):013515-013515-11. · 2.21 Impact Factor
  • J.A. Bossard, D.H. Werner
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    ABSTRACT: A novel nature-inspired technique is used to synthesize fractal random superlattices with custom multispectral filter properties. Fractal random Cantor bars are utilized in the design to reduce the number of parameters required for optimization. A fractal random superlattice is optimized by a genetic algorithm (GA) to exhibit dual pass-bands in the near-infrared regime.
    Antennas and Propagation (APSURSI), 2011 IEEE International Symposium on; 01/2011
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    ABSTRACT: In this paper, the authors present an impedance-matched low loss infrared zero index metamaterials (ZIM) with a wide field-of-view. The ZIM structure is optimized by a genetic algorithm combined with a generalized inversion method capable of retrieving the effective anisotropic constitutive parameters of the metamaterial with its angular response considered.
    Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE; 08/2010
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    ABSTRACT: Over the last few years there has been increasing interest in metamaterials research because of the exciting applications made possible by refractive index engineering. Negative index materials (NIMs) were first theorized in 1968 by Veselago, who predicted that a material possessing simultaneously negative permittivity ε and permeability μ would exhibit novel properties, including backward-propagating waves, near-field focusing, and a modified Snell's law. Pendry's more recent recognition that a flat slab of material with n = -1 could be used as a "perfect lens", started a drive to experimentally demonstrate NIMs from the RF regime through optical wavelengths. However, many NIM experiments have suffered from high absorption and impedance mismatch losses, and most optical NIMs have been very thin with respect to the wavelength, reducing their utility in practical devices. We have previously reported our use of a flexible architecture based on periodic arrays of subwavelength metallo-dielectric structures coupled with genetic algorithm (GA) optimization to minimize the losses inherent in NIMs. We have also investigated optimizing larger metallo-dielectric stacks in order to realize practical, volumetric NIMs. In this paper, we describe our progress in modeling the response of two-layer metallo-dielectric NIMs as well as designing, fabricating and characterizing two-layer metallo-dielectric NIMs for the mid-IR.
    Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE; 08/2010
  • Z. Bayraktar, J.A. Bossard, X. Wang, D.H. Werner
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    ABSTRACT: In this paper, we demonstrate that a successful parallel implementation of CLONALG would decrease the computational burden of multiple calls to the electromagnetic solver by distributing the work load over multiple processors. The optimization of a multi-layered frequency selective surface (FSS) filter for the X-band will be presented and compared with the more traditional parallel genetic algorithm (GA) optimizer in order to demonstrate the effectiveness of the parallel CLONALG implementation in the area of electromagnetics design.
    Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE; 08/2010
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    ABSTRACT: We present several designs for the infrared stand-off detection of passive chemo-sensing absorbers. Two absorbers are implemented as Salisbury Screen Absorbers (SSA) and the third design is implemented using a novel actuated Electromagnetic Band Gap (EBG) structure. Both approaches signal the presence of a chemical analyte via considerable changes in reflectivity. This change is subsequently detected by a thermal imaging camera which operates in the 8-12μm range. In addition to the ease of implementation that results from using ambient lighting, our designs feature a large contrast between states, scalability for long stand-off distances and a wide field of view (FOV). Both designs types are optimized for best performance via a Genetic Algorithm (GA).
    Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE; 08/2010
  • J.A. Bossard, T.M. McManus, D.H. Werner
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    ABSTRACT: Fractal random Cantor superlattices have been proposed in this paper as wavelength selective and broadband filters. Through the use of genetic algorithm optimization, the authors have demonstrated two examples of broadband filters in the mid-IR with a single, broad stop band from 50 THz to 100 THz. These results prove the concept of broadband fractal random superlattices.
    Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE; 08/2010
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    ABSTRACT: In this study, we report multilayer metallo-dielectric stacks that simultaneously possess a zero refractive index and an impedance match to free space in the near-IR. A genetic algorithm (GA) was used to optimize the screen geometries and dimensions of the zero index metamaterials (ZIMs) that consisted of alternating gold (Au) and polyimide films. Examples of three- and nine-layer ZIMs are shown. The fabrication procedure and characterization methods of the multilayer metallo-dielectric ZIMs are also described.
    Proc SPIE 08/2010;