Florian F.L. Bentivegna - Academia.edu (original) (raw)
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Papers by Florian F.L. Bentivegna
HAL (Le Centre pour la Communication Scientifique Directe), 1994
Organically modified silicates (ORMOSILs) were used to encage laser dyes such as rhodamine 6G. Ef... more Organically modified silicates (ORMOSILs) were used to encage laser dyes such as rhodamine 6G. Efficiency as high as 35%, lasing threshold less than 90 muJ, 50 nm tunability around 575 nm and output energy up to 3.5 mJ were achieved. An impregnation process leads to improve the optical properties of solid host matrices.
HAL (Le Centre pour la Communication Scientifique Directe), 1997
We study herein the rotational mobility of organic dye molecules and their ability to align on a ... more We study herein the rotational mobility of organic dye molecules and their ability to align on a strong optical electric field when they are encaged in the pores of an inorganic silica xerogel matrix. We compare the case of dye molecules simply dispersed in the pores of the gel-and possibly held by hydrogen bonds-to the case of molecules chemically grafted on the inner surface of these pores through covalent bonds. The study is led on hybrid silicon-zirconium based inorganic matrices doped with organic rhodamine B molecules. The stronger holding of the dopants when these are grafted to the matrix enhances the molecular alignment-and thus the induced anisotropy-as well as the remanence of this alignment. Furthermore, we show that submitting the samples to a supplementary drying at higher temperature tends to increase both the alignment anisotropy and its stability. We explain these results in terms of mobility of the molecules, in relation to their immediate environment.
Journal of Applied Physics, 2018
We study the influence of the thermo-optic effect and of thermal expansion on the lateral shift e... more We study the influence of the thermo-optic effect and of thermal expansion on the lateral shift experienced by a Gaussian near-infrared beam upon reflection from a voltage-controlled nematic liquid crystal cell deposited on a magnetic yttrium-iron garnet film. Variations of temperature are considered in the range between room temperature and the nematic-isotropic phase transition temperature of the liquid crystal and induce changes in both the layer thicknesses and the permittivity tensor components of the constituents. We show that for all polarization configurations of the incoming and reflected beams, these changes modify the amplitude of the extrema of the lateral beam shift and their position with respect to the incidence angle of the beam and, except in the s-s polarization configuration, to the voltage applied to the liquid crystal cell. In the p-p and p-s polarization configurations, this drift can thus be controlled at some incidence angles by tuning the applied voltage. Moreover, in the p-s configuration, the lateral shift can be also controlled by a magnetization reversal in the magnetic layer. Finally, we discuss the possibility of temperature monitoring using the temperature dependence of the lateral shift in this system.
We theoretically investigate cascading processes for the nonlinear acousto-optical diffraction by... more We theoretically investigate cascading processes for the nonlinear acousto-optical diffraction by standing acoustic waves in a noncentrosymmetric bulk crystal, resulting from the succession of either linear acousto-optic diffraction and sum-frequency generation, or second harmonic generation and linear acousto-optic diffraction. We carefully study the configurations and polarization combinations that allow to distinguish these processes and the direct process of nonlinear acousto-optical diffraction. * * * Nonlinear optical methods are very useful for the investigation of the static and dynamical properties of condensed matter, not only in bulk media, but also in thin films and structured materials. In particular, if a material exhibits a periodic inhomogeneity of its properties, nonlinear diffraction of electromagnetic waves (EMWs) by the resulting permittivity grating can be observed. In a bulk material it is possible to excite transient, dynamic, spatially distributed inhomogenei...
The phenomenon of nonlinear optical diffraction is characterized by diffraction of incident elect... more The phenomenon of nonlinear optical diffraction is characterized by diffraction of incident electromagnetic wave (EMW) with frequency ω at the double frequency 2ω on periodically distributed inhomogeneties which modulate quadratic polarization of a medium, if period of modulation is comparable with the wavelength of second harmonic radiation. If modulation is made by standing acoustic wave in crystal with corresponding wavelength, it would be possible to observe effect of nonlinear acousto-optical diffraction (NAOD) at the frequencies (2ω ± Ω) as was shown in our paper. In this paper we analysed direct transformation of two EMWs into diffracted EMW with doubled frequency which was moduated by standing acoustic wave. In present communication we theoretically investigate cascading effects which also can lead to the NAOD. The sheme of this effect can be presented as follows: in a crystalline plate it is necessary to exite a standing acoustic wave with the wavelength compared with the wavelength of incident EMW. After linear acousto-otical diffraction (stage one), the diffracted beams at frequency (ω ± Ω) may ineract with another incident EMW with frequency ω due to the quadratic nonlinearity (stage two). As the result it would be possible to obtain NAOD signals at frequency (2ω ± Ω). We analyse a possibilities to separate contributions of direct and cascading NAOD signals into observed radiation for nonlinear diffraction by both longitudinal and transversal standing acoustic waves.
Annales de Physique, 2007
ABSTRACT
Les trajectoires d'atomes neutres en interaction quasi-résonante avec un rayonnement laser statio... more Les trajectoires d'atomes neutres en interaction quasi-résonante avec un rayonnement laser stationnaire sont calculées numériquement selon .une approximation semi-classique, afin de simuler la déposition de nanostructures par lithographie atomique. Cette itpproche intuitive se prête également à la mise en oeuvre d'un modèle stochastique de diffusion surfacique des atomes sur leur substrat.
SPIE Proceedings, 2004
ABSTRACT Semiconductor Optical Amplifiers (SOAs) are of central interest as multifunctional, easy... more ABSTRACT Semiconductor Optical Amplifiers (SOAs) are of central interest as multifunctional, easy-to-integrate components for the development of future optoelectronic systems. Their dependence upon the incoming light polarization is a well-known, but still debated, issue in the context of emerging optical telecommunication networks, fueling the need for a detailed polarimetric characterization of such structures. In this paper, we present what we believe to be the first systematic polarimetric analysis within the frame of the Mueller-Stokes formalism of an integrated InP/InGaAsP SOA around 1550 nm. The challenge stems from the amplifying, active, spectrally broadband and nonlinear nature of the component. For the sake of our study, we have developed a highly sensitive, free-space, polarimetric set-up, with the additional experimental challenge induced by the spatial constraints of a guided-wave device, most notably in terms of light injection. Physical phenomena (intrinsic noise contribution of internal sources, carrier saturation due in particular to Amplified Spontaneous Emission, modal birefringence for index and gain...) responsible for the polarization dependence of the amplification process are identified, and discussion of the data highlights the need for an extended matrix formalism taking explicitly internal sources into account.
Journal of the European Optical Society: Rapid Publications, 2007
In this paper, we present a full spectro-polarimetric characterization of the Amplified Spontaneo... more In this paper, we present a full spectro-polarimetric characterization of the Amplified Spontaneous Emission (ASE) emitted from a commercial, strained-bulk Semiconductor Optical Amplifier (SOA). A partly polarised, broadband noise source that draws from the same carrier reservoir as the amplified signal, ASE affects the state of polarisation of the overall outgoing signal of a SOA and its polarimetric behaviour is thus of interest. This study was carried out within the frame of the Stokes formalism, which not only allows a determination of the degree of polarisation (DOP) of ASE directly from its Stokes vector, but also gives access to a full, spectrally resolved characterization of its polarised fraction with respect to the applied bias current. Even when that fraction is small, its state of polarisation was shown to be strongly governed by the spectral dependence of the material gain upon polarisation. The same study was performed with a fully polarised signal injected into the SOA.
The influence of a Kerr nonlinearity on the transmission spectra and Faraday rotation of a one-di... more The influence of a Kerr nonlinearity on the transmission spectra and Faraday rotation of a one-dimensional magnetic photonic crystal is theoretically and numerically analysed.
physica status solidi (a), 2008
ABSTRACT
Photonics and Nanostructures - Fundamentals and Applications, 2012
Journal of the Optical Society of America B, 2011
IEEE Photonics Technology Letters, 2005
A two-cascaded semiconductor optical amplifier configuration in a counterpropagating topology is ... more A two-cascaded semiconductor optical amplifier configuration in a counterpropagating topology is proposed for an alloptical wavelength conversion operation. The attractive issue of the proposed method is that the converted signal can be obtained simultaneously with an inverted and noninverted signal. The all-optical noninverted wavelength conversion feasibility is also demonstrated delivering an extinction ratio higher than 7 dB over a wide range of wavelengths.
Applied Physics B: Lasers and Optics, 1999
ABSTRACT
SPIE Proceedings, 1994
We show that including highly polarizable dopants in the pores of a xerogel matrix leads to inter... more We show that including highly polarizable dopants in the pores of a xerogel matrix leads to interesting optical properties and applications, such as an all-optical molecular memory device. By submitting the sample to ultrashort linearly polarized optical pulses, we demonstrate that the dopants tend to align along the direction of the electric field of the optical wave like in classical
Organic-Inorganic Hybrid Materials for Photonics, 1998
We optically functionalized transparent hybrid matrices prepared by the sol-gel process by doping... more We optically functionalized transparent hybrid matrices prepared by the sol-gel process by doping them with organic chromophores. Highly dense and chemically stable bulk and film materials of good optical quality have been synthesized in this way. Such materials can exhibit very different optical properties, depending on the choice of the chromophores and the type of environment provided by the sol-gel
HAL (Le Centre pour la Communication Scientifique Directe), 1994
Organically modified silicates (ORMOSILs) were used to encage laser dyes such as rhodamine 6G. Ef... more Organically modified silicates (ORMOSILs) were used to encage laser dyes such as rhodamine 6G. Efficiency as high as 35%, lasing threshold less than 90 muJ, 50 nm tunability around 575 nm and output energy up to 3.5 mJ were achieved. An impregnation process leads to improve the optical properties of solid host matrices.
HAL (Le Centre pour la Communication Scientifique Directe), 1997
We study herein the rotational mobility of organic dye molecules and their ability to align on a ... more We study herein the rotational mobility of organic dye molecules and their ability to align on a strong optical electric field when they are encaged in the pores of an inorganic silica xerogel matrix. We compare the case of dye molecules simply dispersed in the pores of the gel-and possibly held by hydrogen bonds-to the case of molecules chemically grafted on the inner surface of these pores through covalent bonds. The study is led on hybrid silicon-zirconium based inorganic matrices doped with organic rhodamine B molecules. The stronger holding of the dopants when these are grafted to the matrix enhances the molecular alignment-and thus the induced anisotropy-as well as the remanence of this alignment. Furthermore, we show that submitting the samples to a supplementary drying at higher temperature tends to increase both the alignment anisotropy and its stability. We explain these results in terms of mobility of the molecules, in relation to their immediate environment.
Journal of Applied Physics, 2018
We study the influence of the thermo-optic effect and of thermal expansion on the lateral shift e... more We study the influence of the thermo-optic effect and of thermal expansion on the lateral shift experienced by a Gaussian near-infrared beam upon reflection from a voltage-controlled nematic liquid crystal cell deposited on a magnetic yttrium-iron garnet film. Variations of temperature are considered in the range between room temperature and the nematic-isotropic phase transition temperature of the liquid crystal and induce changes in both the layer thicknesses and the permittivity tensor components of the constituents. We show that for all polarization configurations of the incoming and reflected beams, these changes modify the amplitude of the extrema of the lateral beam shift and their position with respect to the incidence angle of the beam and, except in the s-s polarization configuration, to the voltage applied to the liquid crystal cell. In the p-p and p-s polarization configurations, this drift can thus be controlled at some incidence angles by tuning the applied voltage. Moreover, in the p-s configuration, the lateral shift can be also controlled by a magnetization reversal in the magnetic layer. Finally, we discuss the possibility of temperature monitoring using the temperature dependence of the lateral shift in this system.
We theoretically investigate cascading processes for the nonlinear acousto-optical diffraction by... more We theoretically investigate cascading processes for the nonlinear acousto-optical diffraction by standing acoustic waves in a noncentrosymmetric bulk crystal, resulting from the succession of either linear acousto-optic diffraction and sum-frequency generation, or second harmonic generation and linear acousto-optic diffraction. We carefully study the configurations and polarization combinations that allow to distinguish these processes and the direct process of nonlinear acousto-optical diffraction. * * * Nonlinear optical methods are very useful for the investigation of the static and dynamical properties of condensed matter, not only in bulk media, but also in thin films and structured materials. In particular, if a material exhibits a periodic inhomogeneity of its properties, nonlinear diffraction of electromagnetic waves (EMWs) by the resulting permittivity grating can be observed. In a bulk material it is possible to excite transient, dynamic, spatially distributed inhomogenei...
The phenomenon of nonlinear optical diffraction is characterized by diffraction of incident elect... more The phenomenon of nonlinear optical diffraction is characterized by diffraction of incident electromagnetic wave (EMW) with frequency ω at the double frequency 2ω on periodically distributed inhomogeneties which modulate quadratic polarization of a medium, if period of modulation is comparable with the wavelength of second harmonic radiation. If modulation is made by standing acoustic wave in crystal with corresponding wavelength, it would be possible to observe effect of nonlinear acousto-optical diffraction (NAOD) at the frequencies (2ω ± Ω) as was shown in our paper. In this paper we analysed direct transformation of two EMWs into diffracted EMW with doubled frequency which was moduated by standing acoustic wave. In present communication we theoretically investigate cascading effects which also can lead to the NAOD. The sheme of this effect can be presented as follows: in a crystalline plate it is necessary to exite a standing acoustic wave with the wavelength compared with the wavelength of incident EMW. After linear acousto-otical diffraction (stage one), the diffracted beams at frequency (ω ± Ω) may ineract with another incident EMW with frequency ω due to the quadratic nonlinearity (stage two). As the result it would be possible to obtain NAOD signals at frequency (2ω ± Ω). We analyse a possibilities to separate contributions of direct and cascading NAOD signals into observed radiation for nonlinear diffraction by both longitudinal and transversal standing acoustic waves.
Annales de Physique, 2007
ABSTRACT
Les trajectoires d'atomes neutres en interaction quasi-résonante avec un rayonnement laser statio... more Les trajectoires d'atomes neutres en interaction quasi-résonante avec un rayonnement laser stationnaire sont calculées numériquement selon .une approximation semi-classique, afin de simuler la déposition de nanostructures par lithographie atomique. Cette itpproche intuitive se prête également à la mise en oeuvre d'un modèle stochastique de diffusion surfacique des atomes sur leur substrat.
SPIE Proceedings, 2004
ABSTRACT Semiconductor Optical Amplifiers (SOAs) are of central interest as multifunctional, easy... more ABSTRACT Semiconductor Optical Amplifiers (SOAs) are of central interest as multifunctional, easy-to-integrate components for the development of future optoelectronic systems. Their dependence upon the incoming light polarization is a well-known, but still debated, issue in the context of emerging optical telecommunication networks, fueling the need for a detailed polarimetric characterization of such structures. In this paper, we present what we believe to be the first systematic polarimetric analysis within the frame of the Mueller-Stokes formalism of an integrated InP/InGaAsP SOA around 1550 nm. The challenge stems from the amplifying, active, spectrally broadband and nonlinear nature of the component. For the sake of our study, we have developed a highly sensitive, free-space, polarimetric set-up, with the additional experimental challenge induced by the spatial constraints of a guided-wave device, most notably in terms of light injection. Physical phenomena (intrinsic noise contribution of internal sources, carrier saturation due in particular to Amplified Spontaneous Emission, modal birefringence for index and gain...) responsible for the polarization dependence of the amplification process are identified, and discussion of the data highlights the need for an extended matrix formalism taking explicitly internal sources into account.
Journal of the European Optical Society: Rapid Publications, 2007
In this paper, we present a full spectro-polarimetric characterization of the Amplified Spontaneo... more In this paper, we present a full spectro-polarimetric characterization of the Amplified Spontaneous Emission (ASE) emitted from a commercial, strained-bulk Semiconductor Optical Amplifier (SOA). A partly polarised, broadband noise source that draws from the same carrier reservoir as the amplified signal, ASE affects the state of polarisation of the overall outgoing signal of a SOA and its polarimetric behaviour is thus of interest. This study was carried out within the frame of the Stokes formalism, which not only allows a determination of the degree of polarisation (DOP) of ASE directly from its Stokes vector, but also gives access to a full, spectrally resolved characterization of its polarised fraction with respect to the applied bias current. Even when that fraction is small, its state of polarisation was shown to be strongly governed by the spectral dependence of the material gain upon polarisation. The same study was performed with a fully polarised signal injected into the SOA.
The influence of a Kerr nonlinearity on the transmission spectra and Faraday rotation of a one-di... more The influence of a Kerr nonlinearity on the transmission spectra and Faraday rotation of a one-dimensional magnetic photonic crystal is theoretically and numerically analysed.
physica status solidi (a), 2008
ABSTRACT
Photonics and Nanostructures - Fundamentals and Applications, 2012
Journal of the Optical Society of America B, 2011
IEEE Photonics Technology Letters, 2005
A two-cascaded semiconductor optical amplifier configuration in a counterpropagating topology is ... more A two-cascaded semiconductor optical amplifier configuration in a counterpropagating topology is proposed for an alloptical wavelength conversion operation. The attractive issue of the proposed method is that the converted signal can be obtained simultaneously with an inverted and noninverted signal. The all-optical noninverted wavelength conversion feasibility is also demonstrated delivering an extinction ratio higher than 7 dB over a wide range of wavelengths.
Applied Physics B: Lasers and Optics, 1999
ABSTRACT
SPIE Proceedings, 1994
We show that including highly polarizable dopants in the pores of a xerogel matrix leads to inter... more We show that including highly polarizable dopants in the pores of a xerogel matrix leads to interesting optical properties and applications, such as an all-optical molecular memory device. By submitting the sample to ultrashort linearly polarized optical pulses, we demonstrate that the dopants tend to align along the direction of the electric field of the optical wave like in classical
Organic-Inorganic Hybrid Materials for Photonics, 1998
We optically functionalized transparent hybrid matrices prepared by the sol-gel process by doping... more We optically functionalized transparent hybrid matrices prepared by the sol-gel process by doping them with organic chromophores. Highly dense and chemically stable bulk and film materials of good optical quality have been synthesized in this way. Such materials can exhibit very different optical properties, depending on the choice of the chromophores and the type of environment provided by the sol-gel