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Enrique Garcia-Caurel

Ecole polytechnique palaiseau, Laboratoire de Physique des Interfaces et des Couches Minces, Faculty Member

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Professional Experience & Goals

I'm looking for opportunities as technology consultant with spectial interest in the areas of optics-photonics, nanotechnology, solar energy generation and micro-electronics.

Research Associate at Ecole Polytechnique since 2003.

My professional activity is focused on
- Research in Ellipsometry and Polarimetry for Materials Characterization
- Research and Development of new optical instruments in collaboration with the industry.
- Exploration of new applications of polarized light.

Specialities
- Development of scientific instruments.
- Optics and Material Science
- Writing Proposals & Management of Reseach Projects
- Reviewer of Research proposals for the ANR (French Research Agengy) and AGAUR (Catalan Research Agency)

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Papers by Enrique Garcia-Caurel

3D structured Bessel beam polarization and its application to imprint chiral optical properties in silica

APL photonics, Jun 1, 2023

Experimental Determination of Optical Constants from Martian Analog Materials Using a Spectro-Polarimetric Approach

HAL (Le Centre pour la Communication Scientifique Directe), Mar 18, 2019

Evidence by Mueller spectropolarimetry of optical rotation imprinted by femtosecond laser in silica

Transmission Mueller-matrix spectroscopy is applied to study femtosecond laser induced modificati... more Transmission Mueller-matrix spectroscopy is applied to study femtosecond laser induced modifications in silica glass in the spectral range 450–1000 nm. Within type II regime, the modifications exhibit not only linear birefringence but also circular birefringence. We reveal that the laser polarization orientation determines the amplitude and the sign of the circular properties.

Ultraviolet phase modulated ellipsometry

HAL (Le Centre pour la Communication Scientifique Directe), 2002

International audienc

Decomposition of angle resolved spectroscopic Mueller matrices from Scarabaeidae beetles

We use angle-dependent Mueller-matrix spectroscopic ellipsometry (MMSE) to determine Mueller matr... more We use angle-dependent Mueller-matrix spectroscopic ellipsometry (MMSE) to determine Mueller matrices of Scarabaeidae beetles which show fascinating reflection properties due to structural phenomena in the exocuticle which are often depolarizing. It has been shown by Cloude [1] that a depolarizing matrix can be decomposed into a sum of up to four non-depolarizing matrices according to M= aM1+bM2+cM3+dM4, where a, b, c and d are eigenvalues of the covariance matrix of M. Using the same eigenvalues the matrices Mi can be calculated. This method provides the full solution to the decomposition with both the non-depolarizing matrices and the weight of each of them in the sum.An alternative to Cloude decomposition is regression decomposition. Here any Mueller matrix can be decomposed into a set of matrices Mi which are specified beforehand. Whereas in Cloude decomposition the only constraint on the matrices is that they are physically realizable non-depolarizing Mueller matrices, we can now limit the constraint and only use Mueller matrices representing pure optical devices having direct physical meaning, such as polarizers, retarders, etc. This leaves a, b, c, d as fit parameters to minimize the Frobenius norm Mexp -Mreg where Mexp is the experimentally determined Mueller matrix to be decomposed and Mreg is the sum of all Mi. Depending on Mexp an appropriate choice of Mreg matrices has to be made and different values of a, b, c and d are obtained through regression analysis.We have previously shown that regression decomposition can be used to show that the Mueller matrix of Cetonia aurata can be decomposed into a sum of a circular polarizer and a mirror [2]. Here we expand the analysis to include angle-resolved spectral Mueller matrices, and also include more species of Scarabaeidae beetles.One effect of the decomposition is that when depolarization is caused by an inhomogeneous sample with regions of different optical properties the Mueller matrices of the different regions can be retrieved under certain conditions. Regression decomposition also has potential to be a classification tool for biological samples where a set of standard matrices are used in the decomposition and the parameters a, b, c, d are used to quantify the polarizing properties of the sample.[1] Cloude S.R. 1989. Conditions for the physical realisability of matrix operators in polarimetry. Proc. SPIE 1166, Polarization Considerations for Optical Systems II, pp. 177-185[2] Arwin H, Magnusson R, Garcia-Caurel E, Fallet C, Jarrendahl K, De Martino A, Ossikovski R, 2015. Sum decomposition of Mueller-matrix images and spectra of beetle cuticles. Opt. Express, vol. 23, no. 3, pp. 1951–1966

Increasing Signal-to-Noise Ratio in Over-Determined Mueller Matrices

Optics Express, Jul 6, 2023

This work investigates how the signal-to-noise ratio (SNR) of an over-determined Mueller matrix c... more This work investigates how the signal-to-noise ratio (SNR) of an over-determined Mueller matrix can be improved by changing the method of calculation. Specifically, our investigation focused on comparing SNRs achieved using the vector methodology from the field of partial Mueller polarimetry, and the matrix methodology. We use experimentally derived measurements from an investigation into the time-varying signal produced by the Mueller matrix of an electro-optic Bismuth Silicon Oxide (BSO) crystal undergoing cyclical impact of a Helium plasma ionisation wave. Our findings show that the vector methodology is superior to the matrix methodology, with a maximum SNR of 7.54 versus 4.97. We put forth that the superiority of the vector methodology is due to its greater flexibility, which results in the Mueller matrix being calculated with better condition matrices, and higher levels of SNR in the intensity measurements used for calculation.

<title>Application of Fourier-transform infrared ellipsometry to quantify bioloical molecules in animal tissues</title>

Proceedings of SPIE, Mar 28, 2002

ABSTRACT Immunohistochemistry contributes to determine the site of origin of the tumor, helps set... more ABSTRACT Immunohistochemistry contributes to determine the site of origin of the tumor, helps setting the treatment and the prognosis. However, these assays are both time consuming when treatment may be an emergency, and expensive. Instead of the usual biochemistry we are using for the first time for medical issues Fourier-transform IR ellipsometry, a non- invasive optical characterization technique used in the semiconductor field to characterize bare substrates and thin films. Working in the mid-IR makes this technique sensitive to the molecules present inside the cell. Since the ellipsometric analysis can be performed on tissue slides extended on a specular surface, they may provide the physician with a chemical map of the sample. Here we show that ellipsometry can detect and measure physiological concentration of glycogen diluted in water and retrieve the polysaccharide band in a tissue slide. Our objective is to show that ellipsometry can give a quick and comprehensive analysis of the diverse biological markers forming the living matter.

Model for the depolarizing retarder in Mueller matrix polarimetry

Journal of the Optical Society of America, Apr 19, 2022

We advance an analytical model describing the polarimetric response of a depolarizing retarder wh... more We advance an analytical model describing the polarimetric response of a depolarizing retarder whose retardance varies spatially in magnitude or in orientation. The variation of the retarder parameters may be either of deterministic or of random nature. The model provides both the mean values and the uncertainties of the parameters. Its application is illustrated on two experimental examples, respectively covering the deterministic and the random cases.

Polarizer calibration method for Mueller matrix polarimeters

Applied Optics, Nov 17, 2020

We advance what we believe is a novel eigenvalue-based method for calibrating Mueller matrix pola... more We advance what we believe is a novel eigenvalue-based method for calibrating Mueller matrix polarimeters employing a single calibration optical component: a polarizer. The method is potentially advantageous in high numerical aperture imaging or wide spectral range spectroscopic polarimetric configurations restricting or even prohibiting the standard use of a retarder as a second calibration component.

Structural circular birefringence and dichroism quantified by differential decomposition of spectroscopic transmission Mueller matrices from Cetonia aurata

Optics Letters, Jul 14, 2016

Determination of optical constants from Martian analog materials using a spectro-polarimetric technique

Planetary and Space Science, 2021

The technique of spectroscopic ellipsometry is a powerful tool for the characterization of the op... more The technique of spectroscopic ellipsometry is a powerful tool for the characterization of the optical properties of materials. This technique represents a significant refinement over the semi-empirical approach to optical constants determination using BRDF (Bidirectional Reflectance Distribution Function) measurements of a finite set of grain sizes for each mineral. It also allows obtaining, not only the optical constants, but also information about the dependence of optical response on sample orientation respect to the illuminating light beam. In this work, we present our experimental approach to derive optical constants of Martian analogue materials based on an infrared ellipsometry technique. We derived the optical constants of gypsum between 750 and 5000 cm À1 (2-13 μm) using data obtained with an infrared spectroscopic Mueller ellipsometer. Thanks to the high sensitivity of the ellipsometric measurements, and despite of a rather complex data analysis protocol, the results obtained for the gypsum samples show that it is possible to successfully use this technique for direct determination of optical constants of natural minerals. The method discussed here can provide the planetary science community with laboratory derived optical constants of a large number of minerals and materials (either natural or synthetic).

Sum regression decomposition of spectral and angle-resolved Mueller matrices from biological reflectors

Applied optics, May 16, 2016

We show spectroscopic Mueller-matrix data measured at multiple incidence angles of the scarab bee... more We show spectroscopic Mueller-matrix data measured at multiple incidence angles of the scarab beetle C. aurata. The Mueller matrix is decomposed by method of regression decomposition and it is shown that this Mueller matrix can be decomposed into a set of two matrices representing one polarizer and one dielectric reflector. We also report on a tentative decomposition of the beetle C. argenteola using the same method.

IR-Mueller matrix ellipsometry of self-assembled nanopatterned gold grid polarizer

Applied Surface Science, Nov 1, 2017

Abstract A gold nanowired grid polarizer is studied in the mid-IR range by means of spectroscopic... more Abstract A gold nanowired grid polarizer is studied in the mid-IR range by means of spectroscopic Mueller matrix ellipsometry. This material is also an example of a so-called 2-dimensional hyperbolic metamaterial/metasurface, and produced by low-cost large area scalable manufacturing techniques. We present the IR spectroscopic Mueller matrix optical response of such sample for a full azimuthal rotation. It is observed strong in-plane anisotropy due to the gold wire grid. The main objective is to show a characterization methodology to reveal the complete polarimetric response over a large spectral range, providing information about the effective optical properties of the sample. Three different optical models are proposed that catch the main features of experimental data. The first one is based on the Rigorous Coupled-Wave Analysis (RCWA) assuming the profile of the sample to be periodic, second, a Generalized Effective Medium Approximation (G-EMA) assuming oriented gold ellipsoids aligned along the lines of the wire grid, and third, a biaxial dispersion model. Experimental data is compared with simulated data obtained from the three optical models and a comparative analysis between them is presented. The different models allow to retrieve information on the characteristic dimensions of the nanowires, and also to obtain the two in-plane components of the effective dielectric tensor of the nanostructured layer. The tensor component parallel to the nanowires shows a metallic response whereas the component perpendicular to them behaves as a transparent dielectric. Moreover, we have also shown that the nanowired grid behaves as a hyperbolic material.

Conservation of the piezoelectric response of PVDF films under irradiation

Radiation Physics and Chemistry, 2018

As opposed to piezo-ceramics (i.e PZT), flexibility and robustness characterize piezoelectric pol... more As opposed to piezo-ceramics (i.e PZT), flexibility and robustness characterize piezoelectric polymers. The main advantage of a piezoelectric polymer, such as Poly (vinylidene fluoride) (PVDF), is an electric power generation under large reversible elastic deformation. Starting from polarized PVDF, we have shown that, despite the fact that irradiation is known to structurally modify the PVDF by introducing defects (radicals, chain scission and crosslinks), the electro-active properties were not affected. At doses lower than 100 kGy, a comparison between swift heavy-ion (SHI) and e-beam irradiations is presented. A homemade device was realized to measure the output voltage as a function of the bending deformation for irradiated and non-irradiated PVDF film. DSC and FT-IR techniques give new insights on which crystalline part or structural change contributes to the conservation of the output voltage. Results suggest that despite the material after irradiation is composed of smaller crystallites, the β-phase content remains stable around 36%, which explains the remarkable preservation of the piezoelectric response in irradiated polarized PVDF films.

Characterization of grating structures by Mueller polarimetry in presence of strong depolarization due to finite spot size and spectral resolution

HAL (Le Centre pour la Communication Scientifique Directe), 2009

In this paper, we present an approach based on Mueller polarimetry for dimensional characterizati... more In this paper, we present an approach based on Mueller polarimetry for dimensional characterization of periodic structures with sample sizes smaller than the illuminating beam spot. The relevant theoretical background based on Mueller matrix formalism is presented. The sample, a photoresist grating box surrounded by silicon substrate, was measured in conical configuration by means of a spectroscopic Mueller polarimeter whose beam was illuminating both the grating and the substrate. By translating the boundary between these two regions through the beam we could follow the depolarization effect related to the incoherent superposition of the light reflected by the grating and the substrate. The grating's optical response was modeled by rigorous coupled-wave analysis. The optimized geometrical parameters of the grating (the line width, the grating depth, and the side-wall angle) show very good consistency for all sample positions with 15% or more of the spot area covered by the grating. Another source of depolarization, the finite spectral resolution of the polarimeter was also taken into account in the analysis, leading to a good quantitative agreement with the sharp ''depolarization lines" observed in the measured Mueller spectra.

Characterization of plasma jets interacting with dielectric and metallic targets: comparison between simulations and experiments

HAL (Le Centre pour la Communication Scientifique Directe), Oct 5, 2020

International audienc

Polarimetric analysis of a fused sphere as a model for adherent particles

Optik, Apr 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Experimental Determination of Optical Constants from Martian Analog Materials Using a Spectro-Polarimetric Approach

HAL (Le Centre pour la Communication Scientifique Directe), Mar 18, 2019

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de

Mueller polarimetric microscopy

HAL (Le Centre pour la Communication Scientifique Directe), 2004

Experimental studies of the transmission of light through low-coverage regular or random arrays of silica micropillars supported by a glass substrate

Applied Optics, 2019

The transmission of light through low coverage regular and random arrays of glass supported silic... more The transmission of light through low coverage regular and random arrays of glass supported silica micropillars of diameters 10 to 40 µm and height 10 µm is studied experimentally. Angle-resolved measurements of the transmitted intensity are performed at visible wavelengths by either a goniospectrophotometer or a multimodal imaging (Mueller) polarimetric microscope. It is demonstrated that for the regular arrays, the angle-resolved measurements are capable of resolving many of the densely packed diffraction orders that are expected for periodic structures of lattice constants 20 to 80 µm, but they also display features that are due to the scattering and guiding of light in individual micropillars or in the supporting glass slides. These latter features are also found in angle-resolved measurements on random arrays of micropillars of the same surface coverage. Finally we perform a comparison of direct measurements of haze in transmission for our patterned glass samples with what can be calculated from the angle-resolved transmitted intensity measurements. Good agreement between the two types of results are found which testifies to the accuracy of the angle-resolved measurements that we report.

3D structured Bessel beam polarization and its application to imprint chiral optical properties in silica

APL photonics, Jun 1, 2023

Experimental Determination of Optical Constants from Martian Analog Materials Using a Spectro-Polarimetric Approach

HAL (Le Centre pour la Communication Scientifique Directe), Mar 18, 2019

Evidence by Mueller spectropolarimetry of optical rotation imprinted by femtosecond laser in silica

Transmission Mueller-matrix spectroscopy is applied to study femtosecond laser induced modificati... more Transmission Mueller-matrix spectroscopy is applied to study femtosecond laser induced modifications in silica glass in the spectral range 450–1000 nm. Within type II regime, the modifications exhibit not only linear birefringence but also circular birefringence. We reveal that the laser polarization orientation determines the amplitude and the sign of the circular properties.

Ultraviolet phase modulated ellipsometry

HAL (Le Centre pour la Communication Scientifique Directe), 2002

International audienc

Decomposition of angle resolved spectroscopic Mueller matrices from Scarabaeidae beetles

We use angle-dependent Mueller-matrix spectroscopic ellipsometry (MMSE) to determine Mueller matr... more We use angle-dependent Mueller-matrix spectroscopic ellipsometry (MMSE) to determine Mueller matrices of Scarabaeidae beetles which show fascinating reflection properties due to structural phenomena in the exocuticle which are often depolarizing. It has been shown by Cloude [1] that a depolarizing matrix can be decomposed into a sum of up to four non-depolarizing matrices according to M= aM1+bM2+cM3+dM4, where a, b, c and d are eigenvalues of the covariance matrix of M. Using the same eigenvalues the matrices Mi can be calculated. This method provides the full solution to the decomposition with both the non-depolarizing matrices and the weight of each of them in the sum.An alternative to Cloude decomposition is regression decomposition. Here any Mueller matrix can be decomposed into a set of matrices Mi which are specified beforehand. Whereas in Cloude decomposition the only constraint on the matrices is that they are physically realizable non-depolarizing Mueller matrices, we can now limit the constraint and only use Mueller matrices representing pure optical devices having direct physical meaning, such as polarizers, retarders, etc. This leaves a, b, c, d as fit parameters to minimize the Frobenius norm Mexp -Mreg where Mexp is the experimentally determined Mueller matrix to be decomposed and Mreg is the sum of all Mi. Depending on Mexp an appropriate choice of Mreg matrices has to be made and different values of a, b, c and d are obtained through regression analysis.We have previously shown that regression decomposition can be used to show that the Mueller matrix of Cetonia aurata can be decomposed into a sum of a circular polarizer and a mirror [2]. Here we expand the analysis to include angle-resolved spectral Mueller matrices, and also include more species of Scarabaeidae beetles.One effect of the decomposition is that when depolarization is caused by an inhomogeneous sample with regions of different optical properties the Mueller matrices of the different regions can be retrieved under certain conditions. Regression decomposition also has potential to be a classification tool for biological samples where a set of standard matrices are used in the decomposition and the parameters a, b, c, d are used to quantify the polarizing properties of the sample.[1] Cloude S.R. 1989. Conditions for the physical realisability of matrix operators in polarimetry. Proc. SPIE 1166, Polarization Considerations for Optical Systems II, pp. 177-185[2] Arwin H, Magnusson R, Garcia-Caurel E, Fallet C, Jarrendahl K, De Martino A, Ossikovski R, 2015. Sum decomposition of Mueller-matrix images and spectra of beetle cuticles. Opt. Express, vol. 23, no. 3, pp. 1951–1966

Increasing Signal-to-Noise Ratio in Over-Determined Mueller Matrices

Optics Express, Jul 6, 2023

This work investigates how the signal-to-noise ratio (SNR) of an over-determined Mueller matrix c... more This work investigates how the signal-to-noise ratio (SNR) of an over-determined Mueller matrix can be improved by changing the method of calculation. Specifically, our investigation focused on comparing SNRs achieved using the vector methodology from the field of partial Mueller polarimetry, and the matrix methodology. We use experimentally derived measurements from an investigation into the time-varying signal produced by the Mueller matrix of an electro-optic Bismuth Silicon Oxide (BSO) crystal undergoing cyclical impact of a Helium plasma ionisation wave. Our findings show that the vector methodology is superior to the matrix methodology, with a maximum SNR of 7.54 versus 4.97. We put forth that the superiority of the vector methodology is due to its greater flexibility, which results in the Mueller matrix being calculated with better condition matrices, and higher levels of SNR in the intensity measurements used for calculation.

<title>Application of Fourier-transform infrared ellipsometry to quantify bioloical molecules in animal tissues</title>

Proceedings of SPIE, Mar 28, 2002

ABSTRACT Immunohistochemistry contributes to determine the site of origin of the tumor, helps set... more ABSTRACT Immunohistochemistry contributes to determine the site of origin of the tumor, helps setting the treatment and the prognosis. However, these assays are both time consuming when treatment may be an emergency, and expensive. Instead of the usual biochemistry we are using for the first time for medical issues Fourier-transform IR ellipsometry, a non- invasive optical characterization technique used in the semiconductor field to characterize bare substrates and thin films. Working in the mid-IR makes this technique sensitive to the molecules present inside the cell. Since the ellipsometric analysis can be performed on tissue slides extended on a specular surface, they may provide the physician with a chemical map of the sample. Here we show that ellipsometry can detect and measure physiological concentration of glycogen diluted in water and retrieve the polysaccharide band in a tissue slide. Our objective is to show that ellipsometry can give a quick and comprehensive analysis of the diverse biological markers forming the living matter.

Model for the depolarizing retarder in Mueller matrix polarimetry

Journal of the Optical Society of America, Apr 19, 2022

We advance an analytical model describing the polarimetric response of a depolarizing retarder wh... more We advance an analytical model describing the polarimetric response of a depolarizing retarder whose retardance varies spatially in magnitude or in orientation. The variation of the retarder parameters may be either of deterministic or of random nature. The model provides both the mean values and the uncertainties of the parameters. Its application is illustrated on two experimental examples, respectively covering the deterministic and the random cases.

Polarizer calibration method for Mueller matrix polarimeters

Applied Optics, Nov 17, 2020

We advance what we believe is a novel eigenvalue-based method for calibrating Mueller matrix pola... more We advance what we believe is a novel eigenvalue-based method for calibrating Mueller matrix polarimeters employing a single calibration optical component: a polarizer. The method is potentially advantageous in high numerical aperture imaging or wide spectral range spectroscopic polarimetric configurations restricting or even prohibiting the standard use of a retarder as a second calibration component.

Structural circular birefringence and dichroism quantified by differential decomposition of spectroscopic transmission Mueller matrices from Cetonia aurata

Optics Letters, Jul 14, 2016

Determination of optical constants from Martian analog materials using a spectro-polarimetric technique

Planetary and Space Science, 2021

The technique of spectroscopic ellipsometry is a powerful tool for the characterization of the op... more The technique of spectroscopic ellipsometry is a powerful tool for the characterization of the optical properties of materials. This technique represents a significant refinement over the semi-empirical approach to optical constants determination using BRDF (Bidirectional Reflectance Distribution Function) measurements of a finite set of grain sizes for each mineral. It also allows obtaining, not only the optical constants, but also information about the dependence of optical response on sample orientation respect to the illuminating light beam. In this work, we present our experimental approach to derive optical constants of Martian analogue materials based on an infrared ellipsometry technique. We derived the optical constants of gypsum between 750 and 5000 cm À1 (2-13 μm) using data obtained with an infrared spectroscopic Mueller ellipsometer. Thanks to the high sensitivity of the ellipsometric measurements, and despite of a rather complex data analysis protocol, the results obtained for the gypsum samples show that it is possible to successfully use this technique for direct determination of optical constants of natural minerals. The method discussed here can provide the planetary science community with laboratory derived optical constants of a large number of minerals and materials (either natural or synthetic).

Sum regression decomposition of spectral and angle-resolved Mueller matrices from biological reflectors

Applied optics, May 16, 2016

We show spectroscopic Mueller-matrix data measured at multiple incidence angles of the scarab bee... more We show spectroscopic Mueller-matrix data measured at multiple incidence angles of the scarab beetle C. aurata. The Mueller matrix is decomposed by method of regression decomposition and it is shown that this Mueller matrix can be decomposed into a set of two matrices representing one polarizer and one dielectric reflector. We also report on a tentative decomposition of the beetle C. argenteola using the same method.

IR-Mueller matrix ellipsometry of self-assembled nanopatterned gold grid polarizer

Applied Surface Science, Nov 1, 2017

Abstract A gold nanowired grid polarizer is studied in the mid-IR range by means of spectroscopic... more Abstract A gold nanowired grid polarizer is studied in the mid-IR range by means of spectroscopic Mueller matrix ellipsometry. This material is also an example of a so-called 2-dimensional hyperbolic metamaterial/metasurface, and produced by low-cost large area scalable manufacturing techniques. We present the IR spectroscopic Mueller matrix optical response of such sample for a full azimuthal rotation. It is observed strong in-plane anisotropy due to the gold wire grid. The main objective is to show a characterization methodology to reveal the complete polarimetric response over a large spectral range, providing information about the effective optical properties of the sample. Three different optical models are proposed that catch the main features of experimental data. The first one is based on the Rigorous Coupled-Wave Analysis (RCWA) assuming the profile of the sample to be periodic, second, a Generalized Effective Medium Approximation (G-EMA) assuming oriented gold ellipsoids aligned along the lines of the wire grid, and third, a biaxial dispersion model. Experimental data is compared with simulated data obtained from the three optical models and a comparative analysis between them is presented. The different models allow to retrieve information on the characteristic dimensions of the nanowires, and also to obtain the two in-plane components of the effective dielectric tensor of the nanostructured layer. The tensor component parallel to the nanowires shows a metallic response whereas the component perpendicular to them behaves as a transparent dielectric. Moreover, we have also shown that the nanowired grid behaves as a hyperbolic material.

Conservation of the piezoelectric response of PVDF films under irradiation

Radiation Physics and Chemistry, 2018

As opposed to piezo-ceramics (i.e PZT), flexibility and robustness characterize piezoelectric pol... more As opposed to piezo-ceramics (i.e PZT), flexibility and robustness characterize piezoelectric polymers. The main advantage of a piezoelectric polymer, such as Poly (vinylidene fluoride) (PVDF), is an electric power generation under large reversible elastic deformation. Starting from polarized PVDF, we have shown that, despite the fact that irradiation is known to structurally modify the PVDF by introducing defects (radicals, chain scission and crosslinks), the electro-active properties were not affected. At doses lower than 100 kGy, a comparison between swift heavy-ion (SHI) and e-beam irradiations is presented. A homemade device was realized to measure the output voltage as a function of the bending deformation for irradiated and non-irradiated PVDF film. DSC and FT-IR techniques give new insights on which crystalline part or structural change contributes to the conservation of the output voltage. Results suggest that despite the material after irradiation is composed of smaller crystallites, the β-phase content remains stable around 36%, which explains the remarkable preservation of the piezoelectric response in irradiated polarized PVDF films.

Characterization of grating structures by Mueller polarimetry in presence of strong depolarization due to finite spot size and spectral resolution

HAL (Le Centre pour la Communication Scientifique Directe), 2009

In this paper, we present an approach based on Mueller polarimetry for dimensional characterizati... more In this paper, we present an approach based on Mueller polarimetry for dimensional characterization of periodic structures with sample sizes smaller than the illuminating beam spot. The relevant theoretical background based on Mueller matrix formalism is presented. The sample, a photoresist grating box surrounded by silicon substrate, was measured in conical configuration by means of a spectroscopic Mueller polarimeter whose beam was illuminating both the grating and the substrate. By translating the boundary between these two regions through the beam we could follow the depolarization effect related to the incoherent superposition of the light reflected by the grating and the substrate. The grating's optical response was modeled by rigorous coupled-wave analysis. The optimized geometrical parameters of the grating (the line width, the grating depth, and the side-wall angle) show very good consistency for all sample positions with 15% or more of the spot area covered by the grating. Another source of depolarization, the finite spectral resolution of the polarimeter was also taken into account in the analysis, leading to a good quantitative agreement with the sharp ''depolarization lines" observed in the measured Mueller spectra.

Characterization of plasma jets interacting with dielectric and metallic targets: comparison between simulations and experiments

HAL (Le Centre pour la Communication Scientifique Directe), Oct 5, 2020

International audienc

Polarimetric analysis of a fused sphere as a model for adherent particles

Optik, Apr 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Experimental Determination of Optical Constants from Martian Analog Materials Using a Spectro-Polarimetric Approach

HAL (Le Centre pour la Communication Scientifique Directe), Mar 18, 2019

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de

Mueller polarimetric microscopy

HAL (Le Centre pour la Communication Scientifique Directe), 2004

Experimental studies of the transmission of light through low-coverage regular or random arrays of silica micropillars supported by a glass substrate

Applied Optics, 2019

The transmission of light through low coverage regular and random arrays of glass supported silic... more The transmission of light through low coverage regular and random arrays of glass supported silica micropillars of diameters 10 to 40 µm and height 10 µm is studied experimentally. Angle-resolved measurements of the transmitted intensity are performed at visible wavelengths by either a goniospectrophotometer or a multimodal imaging (Mueller) polarimetric microscope. It is demonstrated that for the regular arrays, the angle-resolved measurements are capable of resolving many of the densely packed diffraction orders that are expected for periodic structures of lattice constants 20 to 80 µm, but they also display features that are due to the scattering and guiding of light in individual micropillars or in the supporting glass slides. These latter features are also found in angle-resolved measurements on random arrays of micropillars of the same surface coverage. Finally we perform a comparison of direct measurements of haze in transmission for our patterned glass samples with what can be calculated from the angle-resolved transmitted intensity measurements. Good agreement between the two types of results are found which testifies to the accuracy of the angle-resolved measurements that we report.