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While many studies have been conducted on metamaterials at microwave frequencies, comparatively few have examined their use in high-power applications. Here, we perform a general study of metamaterial geometries to identify config...
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While many studies have been conducted on metamaterials at microwave frequencies, comparatively few have examined their use in high-power applications. Here, we perform a general study of metamaterial geometries to identify configurations that are well-suited for utilization in high-power environments. We further develop a genetic algorithm optimization scheme for synthesizing pixelized geometries with artificial magnetic conducting (AMC) properties and reduced maximum field enhancement factor (MFEF).
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This final report details the theoretical and experimental work performed on the project titled, 'A Tunable Laser Source for the Validation of Homogeneous Negative Refractive Index Materials in the Optical Regime' from (AFOSR gran...
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This final report details the theoretical and experimental work performed on the project titled, 'A Tunable Laser Source for the Validation of Homogeneous Negative Refractive Index Materials in the Optical Regime' from (AFOSR grant FA9550-10-1-0399). As part of this DURIP proposal, we have purchased a Bruker Optics Vertex 80 interferometer incorporating a broadband THz lamp and a room temperature KBr/DTGS-D301 photodetector, the AutoSeagull reflection unit and two sets of lasers (Mid-IR and CO2) to build a system for verifying the negative refractive index properties of our homogeneous, low-loss negative index materials in the mid to far-IR wavelength regime.
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In order to more clearly observe the bianisotropic effects due to fabrication-induced structural asymmetries in negative-index metamaterials based on a fishnet structure, it is necessary to measure the optical properties with symm...
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In order to more clearly observe the bianisotropic effects due to fabrication-induced structural asymmetries in negative-index metamaterials based on a fishnet structure, it is necessary to measure the optical properties with symmetric substrate and superstrate bounding layers. This is accomplished in this report using an index-matching fluid and identical substrate and superstrate glass materials.
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he AFOSR project on structural composites with tunable chiral elements has produced some impressive results in the past few years. These include (1) electronically tunable overall chiral composites, (2) mechanically tunable chiral...
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he AFOSR project on structural composites with tunable chiral elements has produced some impressive results in the past few years. These include (1) electronically tunable overall chiral composites, (2) mechanically tunable chiral composites, (3) flat lenses with soft hyperbolic focusing due to indefinite overall permittivity, (4) a tunable flat lens based on chiral elements with adjustable focal spot based on applied mechanical deformation, and (5) a three-phase periodic composite was created that demonstrates positive and negative refraction depending on the input frequency and angle of incidence. A MATLAB code directly computes the group velocity and pass bands for a given set of wave vectors and generates an intuitive plot for quick, but thorough, analysis.
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Metamaterials are artificially constructed materials. When electromagnetic waves propagate through metamaterials they display properties different from those found in natural materials. These different properties can include negat...
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Metamaterials are artificially constructed materials. When electromagnetic waves propagate through metamaterials they display properties different from those found in natural materials. These different properties can include negative refraction (light is bent in the opposite direction from that expected from general laws of physics), flat lens focusing, and subwavelength imaging. The use of meta-materials to direct electromagnetic beams is a highly promising approach to overcome current limitations of conformal antennas by improving the radiation characteristics of antenna elements, especially those at the edge of phased array antennas.
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Based on modern advanced methods of Quantum Optics, we discuss here the possibility of achieving the negative index of refraction in a semiconductor with donor-like impurities. This approach is genuine microscopic, and uses, inste...
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Based on modern advanced methods of Quantum Optics, we discuss here the possibility of achieving the negative index of refraction in a semiconductor with donor-like impurities. This approach is genuine microscopic, and uses, instead of Maxwell equations (homogeneous NIM designs), the Quantum Mechanical methods. This design requires several specially prepared laser beams, one probe beam and several support beams, with specific intensities, frequencies and polarizations. These laser beams pump energy levels and create the desirable density matrix elements of an interest, which, in their turn, produce coherent permeability and permittivity responses at frequency of the probe laser beam.
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An understanding was advanced of nonlinear propagation properties of electromagnetic (EM) waves in double-domain negative/positive index metamaterials (MMs) with focus on the coherent nonlinear-optical (NLO) energy transfer betwee...
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An understanding was advanced of nonlinear propagation properties of electromagnetic (EM) waves in double-domain negative/positive index metamaterials (MMs) with focus on the coherent nonlinear-optical (NLO) energy transfer between the ordinary and backward waves (BWs), i.e. the waves with contra-directed energy flux and phase velocity. A theory was developed and proof-of-principle computational studies were conducted of the outlined processes in the context of particular MMs and their unique potential applications to photonics. Numerical simulations were carried out of the multi-parametric dependences of the solutions to the set of partial differential wave equations accounting for the backwardness of one of the coupled waves. Frequency conversion, which stems from the NLO coupling of contra-propagating short pulses, was studied. A novel approach was proposed to engineering of the MMs, which support coexistence of phase-matched ordinary and BEM eigenmodes satisfying to three-wave mixing. It is based on negative spatial dispersion. A possibility to mimic the outlined extraordinary processes using stimulated Raman scattering on BW optical phonons was shown, which enables greatly enhanced amplification of ordinary Stokes signals.
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This report describes progress accomplished in the past 5 years in the areas of (i) the design of plasmonic near-field plates for visible operation and corrugated near-field plates for point focusing; (ii) synthesis of gold nanopa...
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This report describes progress accomplished in the past 5 years in the areas of (i) the design of plasmonic near-field plates for visible operation and corrugated near-field plates for point focusing; (ii) synthesis of gold nanoparticle patterns; (iii) persistent tuning of metamaterials properties; (iv) experimental demonstration of the magnetic moment of a self- assembled cluster of plasmonic nanoparticles; (v) focused-ion-beam synthesis of nanostructure arrays; (vi) search for negative index in chiral molecule composites; (vii) experimental demonstration of negative-index waves in indefinite-permittivity media, (viii) sub-wavelength mid-IR superlensing and (ix) experimental demonstration of negative-index propagation in sub-wavelength plasmonic metamaterials. We also describe advances in the homogenization theory of arbitrary plasmonic and RF metamaterials and the understanding of bulk properties of low-loss periodic negative index structures, as well as results revealing a close relationship between the dynamic magnetic properties of metamaterials and the permittivity of the inclusions, which impose stringent limits to high-frequency magnetism.
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The research efforts have made following major breakthroughs: 1. Developed new strategy to couple pi-d electrons for the development of molecular metamaterials 2. Explored new mechanism to utilize intermolecular excited states for...
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The research efforts have made following major breakthroughs: 1. Developed new strategy to couple pi-d electrons for the development of molecular metamaterials 2. Explored new mechanism to utilize intermolecular excited states for realizing electric-magnetic coupling towards developing molecular metamaterials 3. Developed new method to use radicals for electric-magnetic coupling towards radicals-based metamaterials 4. Discovered a novel mechanism to generate magneto-optic properties by establishing spin-exchange interaction in electron-hole pairs in ferroelectrically semiconducting materials 5. Developing new strategy to separately control electrical and thermal conductivities by using interfacial polarization
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Metamaterials have ignited a world-wide flurry of research based in part on the realization of negative refractive index, and the idea of coordinate-transformation design of materials leading to exotic phenomena such as electromag...
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Metamaterials have ignited a world-wide flurry of research based in part on the realization of negative refractive index, and the idea of coordinate-transformation design of materials leading to exotic phenomena such as electromagnetic cloaking or energy concentration. The implementation of such ideas is exciting, but is most likely a long-term proposition in terms real- world applications. Briefly, metamaterials are sub-wavelength composites where the electromagnetic response originates from oscillating electrons in highly conducting metals such as gold or copper allowing for a design specific resonant response of the electrical permittivity or magnetic permeability. This is especially important for the technologically relevant terahertz frequency regime where there is a strong need to create components to realize applications ranging from spectroscopic identification of hazardous materials to noninvasive imaging. Our work has been focusing on the development of functional THz metamaterial structures and devices using MEMS technologies, which show extreme power at the micro scale level.
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