In this letter, we describe a very general procedure to obtain a causal fit of the permittivity o... more In this letter, we describe a very general procedure to obtain a causal fit of the permittivity of materials from experimental data with very few parameters. Unlike other closed forms proposed in the literature, the particularity of this approach lies in its independence towards the material or frequency range at stake. Many illustrative numerical examples are given and the accuracy of the fitting is compared to other expressions in the literature.
This document aims at presenting both theoretical and practical aspects of the grating_2D Onelab ... more This document aims at presenting both theoretical and practical aspects of the grating_2D Onelab model (available at http://onelab.info/wiki/Diffraction_grating). This model applies to so-called mono-dimensional grating, i.e. structures having one direction of invariance. Various geometries and materials can be handled or easily added. The two classical polarization cases, denoted here E// and H//, are addressed. The output consists in a full energy balance of the problem computed from the field maps. This model is based on free the GNU softwares Gmsh, GetDP and their interface Onelab.
We extend the design of radially symmetric three-dimensional invisibility cloaks through transfor... more We extend the design of radially symmetric three-dimensional invisibility cloaks through transformation optics to cloaks with a surface of revolution. We derive the expression of the transformation matrix and show that one of its eigenvalues vanishes on the inner boundary of the cloaks, while the other two remain strictly positive and bounded. The validity of our approach is confirmed by finite edge-elements computations for a non-convex cloak of varying thickness.
En 2006, la proposition faite par John Pendry de mettre au point une cape d'invisibilite a co... more En 2006, la proposition faite par John Pendry de mettre au point une cape d'invisibilite a connu un important retentissement mediatique. Derriere cette annonce spectaculaire se profile la silhouette d'une nouvelle approche de l'optique: l'optique transformationnelle. Fondee sur l'invariance des equations fondamentales de l'electromagnetisme par rapport aux deformations de l'espace, elle ouvre une voie novatrice pour la conception des dispositifs nano-technologiques en optique.
Chapter 1: General introduction 1.1 Why have a Science Review? 1.2 What has the Science Review in... more Chapter 1: General introduction 1.1 Why have a Science Review? 1.2 What has the Science Review involved? 1.3 How is scientific knowledge acquired? 1.4 Who has been involved in the Review? 1.5 What is the structure of the Report? 1.6 What is the relationship between this Review and the work of the UK statutory advisory committees on GM? 1.7 How will the Report be used? Chapter 2: Methodology 2.1 Publicity 2.2 The website 2.3 The Science Review Panel 2.4 Open meetings 2.5 Strand coordination 2.6 The Framework of the Review 2.7 The review of public concerns (the Corr Willbourn report) Chapter 3: The role of science in the regulatory process 3.1 Substantial equivalence 3.2 The precautionary principle Chapter 4: How reliable is GM plant breeding? Does GM work? Is GM technology too imprecise? Are GM genes more unstable than resident genes? Is it necessary to produce many transgenic plants to obtain an acceptable one? Chapter 5: The safety of food and animal feed derived from GM crops page 5.4 The fate of transgenic DNA Could transgenes (or parts of their DNA sequences) in food survive digestion and behave differently in comparison to traditional foodstuffs in their ability to relocate, recombine or modify the consumer's genome or that of associated gut microflora? If so, would this pose an increased risk to health compared to the consumption of non-GM derived food? 5.5 The effect of GM derived feed in the food chain Could the consumption of GM derived feed and crops by farm animals prove more of a health hazard to consumers of the resulting food products, or to the animals, than the use of non-GM material? Chapter 6: Environmental impacts of GM crops 6.1 Introduction 6.2 Invasiveness/persistence of GM plants Could GM plants be invasive or persistent, and what might be the impacts? 6.3 Toxicity to wildlife Could GM plants be toxic to wildlife, and what might be the impacts? 6.4 Development of resistance Could crops engineered with novel resistance genes lead to the emergence of new forms of pests, diseases and weeds that are resistant to chemical sprays? Will new forms of insects and diseases evolve which are able to bypass GM resistance genes? 6.5 New weed control strategies offered by GM herbicide tolerant crops Will herbicide tolerant crops offer new weed control strategies and, if so, what are the likely impacts, positive and negative? 6.6 Horizon scanning Apart from herbicide tolerant crops, what are the major new traits that might give rise to significant environmental impacts, positive or negative? 6.7 Changes in agricultural practice Might GM crops change agricultural practice in the UK? If so, what might be the likely consequences? 6.8 Limitations of science Is the science available to predict the environmental impact of GM plants? Chapter 7: Gene flow, detection and impact of GM crops 7.1 Introduction 7.2 Gene flow between crop varieties Can the extent and consequences of gene flow from GM crops to other crop varieties (GM and non-GM) be predicted and controlled? Is coexistence between GM and non-GM crops possible and can we detect unintended GM presence? 7.3 Gene flow from GM crops to agricultural weeds and wild relatives Can the extent and consequences of gene flow from GM crops to agricultural weeds and wild relatives be predicted and controlled? Could gene flow from GM crops generate superweeds or eliminate wild plant populations? 7.4 Can DNA from GM crops transfer to soil microbes? In nature, how important and prevalent is horizontal gene transfer from plants to microbes in the soil, and does the presence of transgenic DNA make this more likely to occur? To what extent are the ecological effects of horizontal gene transfer from plants to soil microbes predictable? 7.5 Can genetic material in GM plants transfer to viruses? Can plant-virus-derived transgenes recombine with, and be transferred to viruses? If horizontal gene transfer is possible between GM plants and viruses could this result in new viruses that could cause irrecoverable damage to the ecosystenm or to crops?
We present exact modal expansions for photonic systems including highly dispersive media. The for... more We present exact modal expansions for photonic systems including highly dispersive media. The formulas, based on a simple version of the Keldyš theorem, are very general since both permeability and permittivity can be dispersive, anisotropic, and even possibly non reciprocal. A simple dispersive test case where both plasmonic and geometrical resonances strongly interact exemplifies the numerical efficiency of our approach.
In this paper we deal with the problem of diffraction of an electromagnetic wave by quasi-periodi... more In this paper we deal with the problem of diffraction of an electromagnetic wave by quasi-periodic multilayered Ž structures. In complete contradiction with the known periodic or random cases, such structures exhibit forbidden bands i.e.. perfect reflection at extremely large wavelengths. q 1998 Elsevier Science B.V.
In this paper, a generalization of cloaking is presented: instead of an empty region of space, an... more In this paper, a generalization of cloaking is presented: instead of an empty region of space, an inhomogeneous structure is transformed via Pendry's map in order to give, to any object hidden in the central hole of the cloak, a completely arbitrary appearance.
We are interested in the two dimensional electromagnetic diffraction by a finite set of parallel ... more We are interested in the two dimensional electromagnetic diffraction by a finite set of parallel non-linear rods (optical Kerr effect). In order to point out the versatility of our approach, a nonlinear (Kerr-effect) finite crystal is considered. Design / methodology / approach We use a method christened "method of the virtual antenna" which allows to simulate an electromagnetic wave radiated by distant sources by the same electromagnetic wave radiated by nearby fictitious sources. This latest problem is then solved by a finite element method. Findings The transmission through a finite Kerr crystal doped by a microcavity is given and a resonant wavelength is obtained. We then show that, at this resonant wavelength, the nonlinearity has a large influence on the local electromagnetic wave. Originality / value We check the results via a verification of the power balance.
Purpose-The purpose of this paper is to present a complete analysis of leaky modes within a micro... more Purpose-The purpose of this paper is to present a complete analysis of leaky modes within a microstructured optical fibre (MOF). Some new numerical results illustrating the versatility and accuracy of our approach are to be given. Design/methodology/approach-A method involving both finite elements and perfectly matched layer (PML) is proposed. Findings-A rigorous definition of the leaky modes is proposed that leads to a proof of the validity of the PML approach together with a rule for the choice of the PML parameters. Originality/value-The choice of parameters associated with the PML are discussed in great detail. The accuracy of the constant of propagation (and especially the imaginary part) are highlighted.
International Journal of Applied Electromagnetics and Mechanics
The propagation of electromagnetic waves in three-dimensional periodic structures is studied here... more The propagation of electromagnetic waves in three-dimensional periodic structures is studied here using the finite (edge) element method. The use of the Floquet-Bloch theory leads to special boundary conditions. In the quasi-static limit, we obtain the effective properties for a periodic array of dielectric spheres and compare these numerical results with two other homogenization approaches, namely Clausius-Mossotti theory and two-scale method.
The photonic-crystal fibre with a suspended core was analyzed in order to explain possibilities o... more The photonic-crystal fibre with a suspended core was analyzed in order to explain possibilities of its using in investigation of electrooptic and magnetooptic effects occurring in the molecules of gas passed into air holes in the fibre. As results from numerical analysis, even 20% of electromagnetic optical energy can be propagating in the area of the air holes. The obtained results indicate the possibility of scanning the electrooptic and magnetooptic effects in photonic-crystal fibres with a suspended core in the case of considerable diminishing of the core (even below 1 µm) or in the case of light applying with its larger wavelengths.
Focusing on the 2p − 1s transition in atomic Hydrogen, we investigate through first order perturb... more Focusing on the 2p − 1s transition in atomic Hydrogen, we investigate through first order perturbation theory the time evolution of the survival probability of an electron initially taken to be in the excited (2p) state. We examine both the results yielded by the standard dipole approximation for the coupling between the atom and the electromagnetic field-for which we propose a cutoff-independent regularisation-and those yielded by the exact coupling function. In both cases, Fermi's golden rule is shown to be an excellent approximation for the system at hand: we found its maximal deviation from the exact behaviour of the system to be of order 10 −8 /10 −7. Our treatment also yields a rigorous prescription for the choice of the optimal cutoff frequency in the dipole approximation. With our cutoff, the predictions of the dipole approximation are almost indistinguishable at all times from the exact dynamics of the system.
In this letter, we describe a very general procedure to obtain a causal fit of the permittivity o... more In this letter, we describe a very general procedure to obtain a causal fit of the permittivity of materials from experimental data with very few parameters. Unlike other closed forms proposed in the literature, the particularity of this approach lies in its independence towards the material or frequency range at stake. Many illustrative numerical examples are given and the accuracy of the fitting is compared to other expressions in the literature.
This document aims at presenting both theoretical and practical aspects of the grating_2D Onelab ... more This document aims at presenting both theoretical and practical aspects of the grating_2D Onelab model (available at http://onelab.info/wiki/Diffraction_grating). This model applies to so-called mono-dimensional grating, i.e. structures having one direction of invariance. Various geometries and materials can be handled or easily added. The two classical polarization cases, denoted here E// and H//, are addressed. The output consists in a full energy balance of the problem computed from the field maps. This model is based on free the GNU softwares Gmsh, GetDP and their interface Onelab.
We extend the design of radially symmetric three-dimensional invisibility cloaks through transfor... more We extend the design of radially symmetric three-dimensional invisibility cloaks through transformation optics to cloaks with a surface of revolution. We derive the expression of the transformation matrix and show that one of its eigenvalues vanishes on the inner boundary of the cloaks, while the other two remain strictly positive and bounded. The validity of our approach is confirmed by finite edge-elements computations for a non-convex cloak of varying thickness.
En 2006, la proposition faite par John Pendry de mettre au point une cape d'invisibilite a co... more En 2006, la proposition faite par John Pendry de mettre au point une cape d'invisibilite a connu un important retentissement mediatique. Derriere cette annonce spectaculaire se profile la silhouette d'une nouvelle approche de l'optique: l'optique transformationnelle. Fondee sur l'invariance des equations fondamentales de l'electromagnetisme par rapport aux deformations de l'espace, elle ouvre une voie novatrice pour la conception des dispositifs nano-technologiques en optique.
Chapter 1: General introduction 1.1 Why have a Science Review? 1.2 What has the Science Review in... more Chapter 1: General introduction 1.1 Why have a Science Review? 1.2 What has the Science Review involved? 1.3 How is scientific knowledge acquired? 1.4 Who has been involved in the Review? 1.5 What is the structure of the Report? 1.6 What is the relationship between this Review and the work of the UK statutory advisory committees on GM? 1.7 How will the Report be used? Chapter 2: Methodology 2.1 Publicity 2.2 The website 2.3 The Science Review Panel 2.4 Open meetings 2.5 Strand coordination 2.6 The Framework of the Review 2.7 The review of public concerns (the Corr Willbourn report) Chapter 3: The role of science in the regulatory process 3.1 Substantial equivalence 3.2 The precautionary principle Chapter 4: How reliable is GM plant breeding? Does GM work? Is GM technology too imprecise? Are GM genes more unstable than resident genes? Is it necessary to produce many transgenic plants to obtain an acceptable one? Chapter 5: The safety of food and animal feed derived from GM crops page 5.4 The fate of transgenic DNA Could transgenes (or parts of their DNA sequences) in food survive digestion and behave differently in comparison to traditional foodstuffs in their ability to relocate, recombine or modify the consumer's genome or that of associated gut microflora? If so, would this pose an increased risk to health compared to the consumption of non-GM derived food? 5.5 The effect of GM derived feed in the food chain Could the consumption of GM derived feed and crops by farm animals prove more of a health hazard to consumers of the resulting food products, or to the animals, than the use of non-GM material? Chapter 6: Environmental impacts of GM crops 6.1 Introduction 6.2 Invasiveness/persistence of GM plants Could GM plants be invasive or persistent, and what might be the impacts? 6.3 Toxicity to wildlife Could GM plants be toxic to wildlife, and what might be the impacts? 6.4 Development of resistance Could crops engineered with novel resistance genes lead to the emergence of new forms of pests, diseases and weeds that are resistant to chemical sprays? Will new forms of insects and diseases evolve which are able to bypass GM resistance genes? 6.5 New weed control strategies offered by GM herbicide tolerant crops Will herbicide tolerant crops offer new weed control strategies and, if so, what are the likely impacts, positive and negative? 6.6 Horizon scanning Apart from herbicide tolerant crops, what are the major new traits that might give rise to significant environmental impacts, positive or negative? 6.7 Changes in agricultural practice Might GM crops change agricultural practice in the UK? If so, what might be the likely consequences? 6.8 Limitations of science Is the science available to predict the environmental impact of GM plants? Chapter 7: Gene flow, detection and impact of GM crops 7.1 Introduction 7.2 Gene flow between crop varieties Can the extent and consequences of gene flow from GM crops to other crop varieties (GM and non-GM) be predicted and controlled? Is coexistence between GM and non-GM crops possible and can we detect unintended GM presence? 7.3 Gene flow from GM crops to agricultural weeds and wild relatives Can the extent and consequences of gene flow from GM crops to agricultural weeds and wild relatives be predicted and controlled? Could gene flow from GM crops generate superweeds or eliminate wild plant populations? 7.4 Can DNA from GM crops transfer to soil microbes? In nature, how important and prevalent is horizontal gene transfer from plants to microbes in the soil, and does the presence of transgenic DNA make this more likely to occur? To what extent are the ecological effects of horizontal gene transfer from plants to soil microbes predictable? 7.5 Can genetic material in GM plants transfer to viruses? Can plant-virus-derived transgenes recombine with, and be transferred to viruses? If horizontal gene transfer is possible between GM plants and viruses could this result in new viruses that could cause irrecoverable damage to the ecosystenm or to crops?
We present exact modal expansions for photonic systems including highly dispersive media. The for... more We present exact modal expansions for photonic systems including highly dispersive media. The formulas, based on a simple version of the Keldyš theorem, are very general since both permeability and permittivity can be dispersive, anisotropic, and even possibly non reciprocal. A simple dispersive test case where both plasmonic and geometrical resonances strongly interact exemplifies the numerical efficiency of our approach.
In this paper we deal with the problem of diffraction of an electromagnetic wave by quasi-periodi... more In this paper we deal with the problem of diffraction of an electromagnetic wave by quasi-periodic multilayered Ž structures. In complete contradiction with the known periodic or random cases, such structures exhibit forbidden bands i.e.. perfect reflection at extremely large wavelengths. q 1998 Elsevier Science B.V.
In this paper, a generalization of cloaking is presented: instead of an empty region of space, an... more In this paper, a generalization of cloaking is presented: instead of an empty region of space, an inhomogeneous structure is transformed via Pendry's map in order to give, to any object hidden in the central hole of the cloak, a completely arbitrary appearance.
We are interested in the two dimensional electromagnetic diffraction by a finite set of parallel ... more We are interested in the two dimensional electromagnetic diffraction by a finite set of parallel non-linear rods (optical Kerr effect). In order to point out the versatility of our approach, a nonlinear (Kerr-effect) finite crystal is considered. Design / methodology / approach We use a method christened "method of the virtual antenna" which allows to simulate an electromagnetic wave radiated by distant sources by the same electromagnetic wave radiated by nearby fictitious sources. This latest problem is then solved by a finite element method. Findings The transmission through a finite Kerr crystal doped by a microcavity is given and a resonant wavelength is obtained. We then show that, at this resonant wavelength, the nonlinearity has a large influence on the local electromagnetic wave. Originality / value We check the results via a verification of the power balance.
Purpose-The purpose of this paper is to present a complete analysis of leaky modes within a micro... more Purpose-The purpose of this paper is to present a complete analysis of leaky modes within a microstructured optical fibre (MOF). Some new numerical results illustrating the versatility and accuracy of our approach are to be given. Design/methodology/approach-A method involving both finite elements and perfectly matched layer (PML) is proposed. Findings-A rigorous definition of the leaky modes is proposed that leads to a proof of the validity of the PML approach together with a rule for the choice of the PML parameters. Originality/value-The choice of parameters associated with the PML are discussed in great detail. The accuracy of the constant of propagation (and especially the imaginary part) are highlighted.
International Journal of Applied Electromagnetics and Mechanics
The propagation of electromagnetic waves in three-dimensional periodic structures is studied here... more The propagation of electromagnetic waves in three-dimensional periodic structures is studied here using the finite (edge) element method. The use of the Floquet-Bloch theory leads to special boundary conditions. In the quasi-static limit, we obtain the effective properties for a periodic array of dielectric spheres and compare these numerical results with two other homogenization approaches, namely Clausius-Mossotti theory and two-scale method.
The photonic-crystal fibre with a suspended core was analyzed in order to explain possibilities o... more The photonic-crystal fibre with a suspended core was analyzed in order to explain possibilities of its using in investigation of electrooptic and magnetooptic effects occurring in the molecules of gas passed into air holes in the fibre. As results from numerical analysis, even 20% of electromagnetic optical energy can be propagating in the area of the air holes. The obtained results indicate the possibility of scanning the electrooptic and magnetooptic effects in photonic-crystal fibres with a suspended core in the case of considerable diminishing of the core (even below 1 µm) or in the case of light applying with its larger wavelengths.
Focusing on the 2p − 1s transition in atomic Hydrogen, we investigate through first order perturb... more Focusing on the 2p − 1s transition in atomic Hydrogen, we investigate through first order perturbation theory the time evolution of the survival probability of an electron initially taken to be in the excited (2p) state. We examine both the results yielded by the standard dipole approximation for the coupling between the atom and the electromagnetic field-for which we propose a cutoff-independent regularisation-and those yielded by the exact coupling function. In both cases, Fermi's golden rule is shown to be an excellent approximation for the system at hand: we found its maximal deviation from the exact behaviour of the system to be of order 10 −8 /10 −7. Our treatment also yields a rigorous prescription for the choice of the optimal cutoff frequency in the dipole approximation. With our cutoff, the predictions of the dipole approximation are almost indistinguishable at all times from the exact dynamics of the system.
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Papers by Frédéric Zolla