Metamaterials made of asymmetric cut wire pairs have theoretically and experimentally demonstrate... more Metamaterials made of asymmetric cut wire pairs have theoretically and experimentally demonstrated a negative refractive index at microwave frequencies. In this paper, using simulations and experiments in the microwave domain, we investigate the influence of oblique incidence on the resonances and retrieved refractive index of the asymmetric cut wire pairs. While it is found that resonances shift in frequency with increasing oblique incidence in the E-plane, it is shown that the structure is angle-independent in the H-plane. It is reported that a diffraction threshold appears in E-plane, that is the (-1,0) mode starts to propagate. Besides, resonances in E-plane shift in frequency with increasing oblique incidence.
Metamaterials made of exclusively metallic cut wire pairs have been experimentally demonstrated t... more Metamaterials made of exclusively metallic cut wire pairs have been experimentally demonstrated to exhibit a negative refractive index at optical frequencies. However, other related works have not shown a negative index. In this paper, we propose an easy way to manipulate the magnetic and electric resonances of these metamaterials to produce a negative index. We show that judiciously breaking the symmetry of the structure allows tuning of both resonances leading to an overlapping between the negative permeability and negative permittivity regions. Numerical and experimental parametric studies of several cut wire pairs metamaterials are presented to validate our method at microwave frequencies.
We present, design and analyze a novel planar Left-Handed (LH) metamaterial in the microwave regi... more We present, design and analyze a novel planar Left-Handed (LH) metamaterial in the microwave region. This metamaterial is composed of only cut metallic wires and is used under normal-to-plane incidence. Using Finite Element Method (FEM) based simulations and microwave experiments, we have investigated the material properties of the structure. Simultaneous negative values are observed for the permittivity e and permeability m by the inversion method from the transmission and reflection responses. A negative index n is verified in a bulk prism engineered by stacking several layers of the metamaterial. Our work demonstrates the feasibility of a LH metamaterial composed of only cut wires.
This article deals with the modeling, practical implementation, and characterization of an azimut... more This article deals with the modeling, practical implementation, and characterization of an azimuthal directive antenna around 10 GHz. The design of the antenna is based on transformation optics concept by transforming the radiation of a plane source into an azimuthal radiation. This coordinate transformation procedure is achieved by modifying the electromagnetic properties of the space around the plane source. Metamaterials presenting electric and magnetic resonances are used to produce the effective material parameters necessary for the transformation. S11 parameter and direct far-field measurements are performed on a fabricated prototype to experimentally demonstrate the narrow beam profile and the beam deflection.
Metamaterials have paved the way to unprecedented control of the electromagnetic field1,2. The co... more Metamaterials have paved the way to unprecedented control of the electromagnetic field1,2. The conjunction with space coordinate transformation has led to a novel "relativity inspired" approach for the control of light propagation. "Invisibility cloak" is the most fascinating proposed devices3,4. However, the realized structures up to now used a graded "metamagnetic" so as to achieve the cloaking function11. Artificial magnetism
2013 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, 2013
ABSTRACT We address the potential of a metamaterials in a guided wave configuration for applicati... more ABSTRACT We address the potential of a metamaterials in a guided wave configuration for applications in the near IR domain. We consider a hybrid type structure made of 2D metamaterial array over a high index slab waveguide, as for instance silicon our case. The experimental and modeling results show that effective index and loss level in such hybrid waveguides can be carefully controlled by the engineering of metamaterial resonances. The investigated approach may constitute a promising alternative to the bulk multi-layers metamaterial structures.
Dielectric substrates supporting planar periodic subwavelength metamaterial-based metallic arrays... more Dielectric substrates supporting planar periodic subwavelength metamaterial-based metallic arrays and presenting frequency dispersive phase characteristics are applied to ultra-compact high-gain and high-directivity planar antennas. In this paper, different models of metamaterial-based surfaces introducing a zero degree reflection phase shift to incident waves are firstly studied numerically using finite-element method analysis where the bandwidth and operation frequency are predicted. These surfaces are then applied in a resonant Fabry-Perot type cavity and a ray optics analysis is used to design different models of ultra-compact high-gain microstrip printed antennas. Firstly, a cavity antenna of thickness λ/60 based on the use of a microstrip patch antenna and two bidimensional metamaterial-based surfaces, the first one acting as a High Impedance Surface (HIS) and the second one acting as a Partially Reflecting Surface (PRS) is designed. This cavity is then optimized for easier fabrication process and loss reduction by the use of only one bidimensionnal composite metamaterial-based surface acting as a PRS. Secondly, another surface presenting a variable phase by the use of a non periodic metamaterial-based metallic strips array is designed for a passive low-profile steering beam antenna application. Finally, a switchable operation frequency cavity by the implementation of varicap diodes is designed and fabricated. All these cavity antennas operate on subwavelength modes, the smallest cavity thickness being of the order of λ/60.
ABSTRACT Using interferometric measurements and theoretical calculations, we show that a refracti... more ABSTRACT Using interferometric measurements and theoretical calculations, we show that a refractive index can be appropriately assigned to a thin plasmonic metafilm on a high-permittivity dielectric. A full analysis in amplitude and in phase of the composite metafilm made of metallic nanoresonators and wires is reported around the first plasmonic resonance. It reveals that contrary to solely intensity measurements, the phase behavior of the air/metafilm/dielectric system dramatically depends on both the damping effects and the dielectric index. A simple model is derived which can apply to various situations in plasmonics and optical metamaterials.
The so-called PT symmetric devices, which feature * () () x x ε ε − = associated with parity-time... more The so-called PT symmetric devices, which feature * () () x x ε ε − = associated with parity-time symmetry, incorporate both gain and loss and can present a singular eigenvalue behaviour around a critical transition point. The scheme, typically based on co-directional coupled waveguides, is here transposed to the case of variable gain on one arm with fixed losses on the other arm. In this configuration, the scheme exploits the full potential of plasmonics by making a beneficial use of their losses to attain a critical regime that makes switching possible with much lowered gain excursions. Practical implementations are discussed based on existing attempts to elaborate coupled waveguide in plasmonics, and based also on the recently proposed hybrid plasmonics waveguide structure with a small low-index gap, the PIROW (Plasmonic Inverse-Rib Optical Waveguide).
In-plane coupling between the second plasmonic mode of split ring resonators and delocalized plas... more In-plane coupling between the second plasmonic mode of split ring resonators and delocalized plasmons of nanowires is experimentally demonstrated from far-field measurements in metasurfaces with critical separation distances between nanostructures. Near-field calculations show that coupling drastically depends on both ``meta-atom'' shapes and separation distances. The associated field enhancement reveals these metasurfaces as good candidates for applications to sensing and surface enhanced spectroscopy.
Photonics and Nanostructures - Fundamentals and Applications, 2010
ABSTRACT Metamaterial building blocks from microwave to optical range are mainly based on metal-d... more ABSTRACT Metamaterial building blocks from microwave to optical range are mainly based on metal-dielectric composites. In almost all structures with true negative index (not coming from losses), two kinds of meta-atoms (electric and magnetic) are mixed to drive simultaneously the effective permittivity and permeability to negative values leading in turn to a negative index of refraction. In this paper, we show that two coupled structures with localized plasmons modes (e.g. cut-wires or split ring resonators) can exhibit negative refractive index by their own, by appropriately controlling the hybridization scheme of the plasmons modes. Because of small metal filling factor and reduced optical losses, the resulting structures may pave the way to realistic applications of metamaterials at optical frequencies.
Photonics and Nanostructures - Fundamentals and Applications, 2007
In this study, we propose guidelines to optimize the transmission and bandwidth of left handed ma... more In this study, we propose guidelines to optimize the transmission and bandwidth of left handed materials (LHM) composed of two-dimensional lattice of metallic wires interleaved with double split ring resonators (SRRs). Several LHM structures are fabricated to test the proposed rules of design and operate between 7 and 14GHz. In a first step, we show that adding extra SRR layers
Engineering resonances in metamaterials has been so far the main way of reaching simultaneously n... more Engineering resonances in metamaterials has been so far the main way of reaching simultaneously negative permittivity and negative permeability leading to negative index materials. In this paper, we present an experimental and numerical analysis of the infrared response of metamaterials made of continuous nanowires and split ring resonators (SRR) deposited on low-doped silicon when the geometry of the SRRs is gradually altered. The impact of the geometric transformation of the SRRs on the spectra of the composite metamaterial is measured in the 20-200 THz frequency range (i.e., in the 1.5-15 microm wavelength range) for the two field polarizations under normal to plane propagation. We show experimentally and numerically that tuning the SRRs towards elementary cut wires translates in a predictable manner the frequency response of the artificial material. We also analyze coupling effects between the SRRs and the continuous nanowires for different spacings between them. The results of our study are expected to provide useful guidelines for the design of negative index metamaterials on silicon.
Metamaterials made of asymmetric cut wire pairs have theoretically and experimentally demonstrate... more Metamaterials made of asymmetric cut wire pairs have theoretically and experimentally demonstrated a negative refractive index at microwave frequencies. In this paper, using simulations and experiments in the microwave domain, we investigate the influence of oblique incidence on the resonances and retrieved refractive index of the asymmetric cut wire pairs. While it is found that resonances shift in frequency with increasing oblique incidence in the E-plane, it is shown that the structure is angle-independent in the H-plane. It is reported that a diffraction threshold appears in E-plane, that is the (-1,0) mode starts to propagate. Besides, resonances in E-plane shift in frequency with increasing oblique incidence.
Metamaterials made of exclusively metallic cut wire pairs have been experimentally demonstrated t... more Metamaterials made of exclusively metallic cut wire pairs have been experimentally demonstrated to exhibit a negative refractive index at optical frequencies. However, other related works have not shown a negative index. In this paper, we propose an easy way to manipulate the magnetic and electric resonances of these metamaterials to produce a negative index. We show that judiciously breaking the symmetry of the structure allows tuning of both resonances leading to an overlapping between the negative permeability and negative permittivity regions. Numerical and experimental parametric studies of several cut wire pairs metamaterials are presented to validate our method at microwave frequencies.
We present, design and analyze a novel planar Left-Handed (LH) metamaterial in the microwave regi... more We present, design and analyze a novel planar Left-Handed (LH) metamaterial in the microwave region. This metamaterial is composed of only cut metallic wires and is used under normal-to-plane incidence. Using Finite Element Method (FEM) based simulations and microwave experiments, we have investigated the material properties of the structure. Simultaneous negative values are observed for the permittivity e and permeability m by the inversion method from the transmission and reflection responses. A negative index n is verified in a bulk prism engineered by stacking several layers of the metamaterial. Our work demonstrates the feasibility of a LH metamaterial composed of only cut wires.
This article deals with the modeling, practical implementation, and characterization of an azimut... more This article deals with the modeling, practical implementation, and characterization of an azimuthal directive antenna around 10 GHz. The design of the antenna is based on transformation optics concept by transforming the radiation of a plane source into an azimuthal radiation. This coordinate transformation procedure is achieved by modifying the electromagnetic properties of the space around the plane source. Metamaterials presenting electric and magnetic resonances are used to produce the effective material parameters necessary for the transformation. S11 parameter and direct far-field measurements are performed on a fabricated prototype to experimentally demonstrate the narrow beam profile and the beam deflection.
Metamaterials have paved the way to unprecedented control of the electromagnetic field1,2. The co... more Metamaterials have paved the way to unprecedented control of the electromagnetic field1,2. The conjunction with space coordinate transformation has led to a novel "relativity inspired" approach for the control of light propagation. "Invisibility cloak" is the most fascinating proposed devices3,4. However, the realized structures up to now used a graded "metamagnetic" so as to achieve the cloaking function11. Artificial magnetism
2013 7th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, 2013
ABSTRACT We address the potential of a metamaterials in a guided wave configuration for applicati... more ABSTRACT We address the potential of a metamaterials in a guided wave configuration for applications in the near IR domain. We consider a hybrid type structure made of 2D metamaterial array over a high index slab waveguide, as for instance silicon our case. The experimental and modeling results show that effective index and loss level in such hybrid waveguides can be carefully controlled by the engineering of metamaterial resonances. The investigated approach may constitute a promising alternative to the bulk multi-layers metamaterial structures.
Dielectric substrates supporting planar periodic subwavelength metamaterial-based metallic arrays... more Dielectric substrates supporting planar periodic subwavelength metamaterial-based metallic arrays and presenting frequency dispersive phase characteristics are applied to ultra-compact high-gain and high-directivity planar antennas. In this paper, different models of metamaterial-based surfaces introducing a zero degree reflection phase shift to incident waves are firstly studied numerically using finite-element method analysis where the bandwidth and operation frequency are predicted. These surfaces are then applied in a resonant Fabry-Perot type cavity and a ray optics analysis is used to design different models of ultra-compact high-gain microstrip printed antennas. Firstly, a cavity antenna of thickness λ/60 based on the use of a microstrip patch antenna and two bidimensional metamaterial-based surfaces, the first one acting as a High Impedance Surface (HIS) and the second one acting as a Partially Reflecting Surface (PRS) is designed. This cavity is then optimized for easier fabrication process and loss reduction by the use of only one bidimensionnal composite metamaterial-based surface acting as a PRS. Secondly, another surface presenting a variable phase by the use of a non periodic metamaterial-based metallic strips array is designed for a passive low-profile steering beam antenna application. Finally, a switchable operation frequency cavity by the implementation of varicap diodes is designed and fabricated. All these cavity antennas operate on subwavelength modes, the smallest cavity thickness being of the order of λ/60.
ABSTRACT Using interferometric measurements and theoretical calculations, we show that a refracti... more ABSTRACT Using interferometric measurements and theoretical calculations, we show that a refractive index can be appropriately assigned to a thin plasmonic metafilm on a high-permittivity dielectric. A full analysis in amplitude and in phase of the composite metafilm made of metallic nanoresonators and wires is reported around the first plasmonic resonance. It reveals that contrary to solely intensity measurements, the phase behavior of the air/metafilm/dielectric system dramatically depends on both the damping effects and the dielectric index. A simple model is derived which can apply to various situations in plasmonics and optical metamaterials.
The so-called PT symmetric devices, which feature * () () x x ε ε − = associated with parity-time... more The so-called PT symmetric devices, which feature * () () x x ε ε − = associated with parity-time symmetry, incorporate both gain and loss and can present a singular eigenvalue behaviour around a critical transition point. The scheme, typically based on co-directional coupled waveguides, is here transposed to the case of variable gain on one arm with fixed losses on the other arm. In this configuration, the scheme exploits the full potential of plasmonics by making a beneficial use of their losses to attain a critical regime that makes switching possible with much lowered gain excursions. Practical implementations are discussed based on existing attempts to elaborate coupled waveguide in plasmonics, and based also on the recently proposed hybrid plasmonics waveguide structure with a small low-index gap, the PIROW (Plasmonic Inverse-Rib Optical Waveguide).
In-plane coupling between the second plasmonic mode of split ring resonators and delocalized plas... more In-plane coupling between the second plasmonic mode of split ring resonators and delocalized plasmons of nanowires is experimentally demonstrated from far-field measurements in metasurfaces with critical separation distances between nanostructures. Near-field calculations show that coupling drastically depends on both ``meta-atom'' shapes and separation distances. The associated field enhancement reveals these metasurfaces as good candidates for applications to sensing and surface enhanced spectroscopy.
Photonics and Nanostructures - Fundamentals and Applications, 2010
ABSTRACT Metamaterial building blocks from microwave to optical range are mainly based on metal-d... more ABSTRACT Metamaterial building blocks from microwave to optical range are mainly based on metal-dielectric composites. In almost all structures with true negative index (not coming from losses), two kinds of meta-atoms (electric and magnetic) are mixed to drive simultaneously the effective permittivity and permeability to negative values leading in turn to a negative index of refraction. In this paper, we show that two coupled structures with localized plasmons modes (e.g. cut-wires or split ring resonators) can exhibit negative refractive index by their own, by appropriately controlling the hybridization scheme of the plasmons modes. Because of small metal filling factor and reduced optical losses, the resulting structures may pave the way to realistic applications of metamaterials at optical frequencies.
Photonics and Nanostructures - Fundamentals and Applications, 2007
In this study, we propose guidelines to optimize the transmission and bandwidth of left handed ma... more In this study, we propose guidelines to optimize the transmission and bandwidth of left handed materials (LHM) composed of two-dimensional lattice of metallic wires interleaved with double split ring resonators (SRRs). Several LHM structures are fabricated to test the proposed rules of design and operate between 7 and 14GHz. In a first step, we show that adding extra SRR layers
Engineering resonances in metamaterials has been so far the main way of reaching simultaneously n... more Engineering resonances in metamaterials has been so far the main way of reaching simultaneously negative permittivity and negative permeability leading to negative index materials. In this paper, we present an experimental and numerical analysis of the infrared response of metamaterials made of continuous nanowires and split ring resonators (SRR) deposited on low-doped silicon when the geometry of the SRRs is gradually altered. The impact of the geometric transformation of the SRRs on the spectra of the composite metamaterial is measured in the 20-200 THz frequency range (i.e., in the 1.5-15 microm wavelength range) for the two field polarizations under normal to plane propagation. We show experimentally and numerically that tuning the SRRs towards elementary cut wires translates in a predictable manner the frequency response of the artificial material. We also analyze coupling effects between the SRRs and the continuous nanowires for different spacings between them. The results of our study are expected to provide useful guidelines for the design of negative index metamaterials on silicon.
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Papers by André Lustrac
Element Method (FEM) based simulations and microwave experiments, we have investigated the material properties of the structure. Simultaneous negative values are observed for the permittivity e and permeability m by the inversion method from the transmission and reflection responses. A negative index n is verified in a bulk prism engineered by stacking several layers of the metamaterial. Our work demonstrates the feasibility of a LH metamaterial composed of only cut wires.
Element Method (FEM) based simulations and microwave experiments, we have investigated the material properties of the structure. Simultaneous negative values are observed for the permittivity e and permeability m by the inversion method from the transmission and reflection responses. A negative index n is verified in a bulk prism engineered by stacking several layers of the metamaterial. Our work demonstrates the feasibility of a LH metamaterial composed of only cut wires.