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Papers by François Flory

Research paper thumbnail of Optical anisotropy of thin-film materials measured with guided wave techniques

Annual Meeting Optical Society of America

Accurate measurements of coupling angles (m-lines method) corresponding to different propagation ... more Accurate measurements of coupling angles (m-lines method) corresponding to different propagation modes in a layer can reveal an optical anisotropy of the material constituting that layer. In the case of a layer obtained by evaporation condensation, this anisotropy can be directly correlated with the shape and the direction of the columns which are the main characteristics of the microstructure. Starting with the hypothesis of a birefringent structure with one of the optical axes oriented in the columnar growth direction, we have a calculation method for simultaneously determining the layer thickness and the indices corresponding to the principal axes. We show that the anisotropy depends in a critical way on the evaporation conditions: it is much marked when the layers have a more lacunar structure. And, for a coating made under oblique incidence, anisotropy increases with the angle of incidence. If the substrate is moved during deposition, the columnar growth is perturbed and anisot...

Research paper thumbnail of Interpretation of measurements of both losses on guided propagation and absorption from a model of absorbing transition layers

Optical Interference Coatings, 1994

ABSTRACT

Research paper thumbnail of <title>Utility of multidielectric coatings for realization of waveguides</title>

Optical Interference Coatings, 1994

The usefulness of multilayer optical coatings for realization of waveguides is discussed. Such gu... more The usefulness of multilayer optical coatings for realization of waveguides is discussed. Such guides are used to study the origin of losses. In particular it is shown that a model taking into account transition absorbing layers gives good explanation of the dispersion of the measured losses during propagation for the different guided modes. On the other hand a multilayer structure which could be efficiently coupled to a single mode optical fiber is presented.

Research paper thumbnail of Characterizations of thin films for optical microcomponents

Optical Interference Coatings, 2001

ABSTRACT

Research paper thumbnail of Thin films for optical systems

Research paper thumbnail of Optical Thin Films for Micro-Components

Springer Series in Optical Sciences, 2003

Research paper thumbnail of <title>Ion implantation in dielectric thin films for passive and active components</title>

Third International Conference on Thin Film Physics and Applications, 1998

ABSTRACT The consequences of Ti implantation in silica glasses and Ta2O5 layer are studied. It is... more ABSTRACT The consequences of Ti implantation in silica glasses and Ta2O5 layer are studied. It is shown that the optical losses can be low with a variation of the refractive index which can be well controlled. Results on rectangular waveguides and Y junctions are given. Erbium implanted Ta2O5 layers exhibit a luminescent behavior both in the green and in the infra-red. The emission diagram of the coating can be controlled with a multilayer structure.

Research paper thumbnail of Refractive index modifications and thermal properties of optical thin films with the prism coupler

Fourth International Conference on Thin Film Physics and Applications, 2000

The prism coupler can be used with a single beam to measure the refractive indices of isotropic o... more The prism coupler can be used with a single beam to measure the refractive indices of isotropic or anisotropic single layers and of layers in multilayer stacks with an accuracy of 1. X 10-3. The refractive index modification with temperature can also be measured easily. The refractive index of a thin film can also change under illumination. A two-beam set-up

Research paper thumbnail of Mesures de propriétés non linéaires thermiques de couches minces diélectriques

Optique instrumentale, 1997

Research paper thumbnail of <title>Enhancement of the diffraction efficiency of titanium implanted gratings by associating them with optical interference coatings</title>

Advances in Optical Interference Coatings, 1999

ABSTRACT Refractive index gratings made by titanium ion implantation are studied. Computations us... more ABSTRACT Refractive index gratings made by titanium ion implantation are studied. Computations using the rigorous differential method and otpical measurements show that our gratings implanted in SiO2 substrates have a diffraction efficiency of typically 2 percent in the 1st order. We propose to insert such grating in multilayer dielectric Fabry-Perot cavities in order to enhance the free space diffraction efficiency. Computations are performed by taking into account the index profile of the implanted zone. The best structure is obtained by optimizing the thickness of the implanted silica layer which is embedded between two mirrors. We study the dependence of optical properties of the structure with respect to various characteristic parameters such as the index profile, the multilayer design, the filling factor of the grating and the incident angle. To demonstrate the feasibility of such components, we focus our attention on an implanted grating embedded in a Fabry-Perot cavity whose mirrors have five dielectric layers. This component reaches a theoretical efficiency of 10 percent in the 1st order. First experimental results are presented.

Research paper thumbnail of Integrated Polarization Rotator and Splitter Made of Sputtered Ta<inf>2</inf>0<inf>5</inf> and Inorganic Silica Thin Films

2006 European Conference on Optical Communications, 2006

ABSTRACT Integrated polarization rotator and splitter, made with a new ridge waveguide technology... more ABSTRACT Integrated polarization rotator and splitter, made with a new ridge waveguide technology, have been simulated and realized with optical photolithography and lift off process. Experimental results show effective rotation and splitting with low cross-talk levels.

Research paper thumbnail of Is it opportune to study laser-induced damage of coatings by optical characterization?

SPIE Proceedings, 1999

High quality thin films completely free of defects is the goal for higher damage threshold but it... more High quality thin films completely free of defects is the goal for higher damage threshold but it remains a dream. Specific means of characterization to measure absorption losses by photothermal deflection and scattering losses are currently used. The analysis of experimental results permits to understand how the real behavior of thin films can be affected by localized defects. With the development of the mapping technique, the comparison between absorption and scattering intensity maps of the surface of coatings appears to be a good tool for this study. Moreover we need a more basic information concerning the multilayer under study and characterization by guided wave appears to be really fruitful. It permits the determination of the refractive index and the thickness of the different layers. Additional measurements of attenuation of guided waves can be used for the location of the absorption sites in the depth of the coating.

Research paper thumbnail of <title>Surface plasmon effect on metallic nanoparticles integrated in organic solar cells</title>

Optical Complex Systems: OCS11, 2011

Experimental results concerning the influence of plasmon effect from silver nanoparticles on the ... more Experimental results concerning the influence of plasmon effect from silver nanoparticles on the organic photovoltaic device performance are presented. The metallic nanoparticles (NPs) are placed on top of ITO layer using a physical vapor deposition technique. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) followed by an interpenetrated poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) blend layer are then spin-coated. The aluminum electrode is finally evaporated on.

Research paper thumbnail of Morphology and structure of TiO2 thin layers vs. thickness and substrate temperature

Thin Solid Films, 1989

Abstract TiO 2 thin layers are often used in multilayer coatings for optical filters and this mak... more Abstract TiO 2 thin layers are often used in multilayer coatings for optical filters and this makes their study especially interesting. Different TiO 2 thin layers corresponding to different thicknesses and deposited at different temperatures have been prepared by vapour deposition onto amorphous substrates. Most of these layers are amorphous but small crystals of anatase and rutile can also exist. These crystals are more frequent (i) if the substrate temperature is raised (350 °C) and/or (ii) if the thickness of the thin layer is higher. The surface roughness of TiO 2 thin layers has also been investigated by electron microscopy by two different and complementary methods: direct imaging by transmission electron microscopy and carbon-platinum replica observation. The thin layer surfaces are rather irregular, and this practically independently of the film thickness and of the substrate temperature during the deposition. Surface irregularities have been measured to reach about 10 nm. They have been shown to be slightly reduced on increasing the thin layer thicknesses from 35 to 70 nm. Each layer is made of blocks about 40 nm in size and each block is made of smaller blocks (about ten times smaller). The origin of this phenomenon has been sought. The formation of the smaller blocks is in agreement with existing theories of nucleation and growth of amorphous thin films. An attempt to find the origin of the larger blocks has also been carried out. This could be related to the permanent chemical transformation occuring during the thin layer formation. Finally, we relate the optical properties of the TiO 2 thin layers to their morphology and structure.

Research paper thumbnail of Gratings in resonant multilayer structures

Fourth International Conference on Thin Film Physics and Applications, 2000

Enhancement of the free-space diffraction efficiency of titanium-ion implanted gratings by insert... more Enhancement of the free-space diffraction efficiency of titanium-ion implanted gratings by inserting them into multilayer dielectric Fabry-Perot cavities has been demonstrated theoretically in previous works. In this paper, we discuss the sensitivity of the diffraction efficiency to the optogeometrical parameters of the structures obtained using titanium-ion implantation. A process to perform a phase grating in a seven-layer mirror Fabry-Perot cavity

Research paper thumbnail of Laser Deposition of Waveguiding Films

Nato Science Series

ABSTRACT

Research paper thumbnail of Wavelength and temperature dispersion of refractive index of thin films

Optical Complex Systems: Ocs11, 2011

The m-lines guided mode technique is demonstrated as a powerful tool for the measurement of wavel... more The m-lines guided mode technique is demonstrated as a powerful tool for the measurement of wavelength and temperature refractive index dispersion in thin films. The proper treatment of results reveals measurement uncertainties of the order of 10-3 for the refractive index, and a sensitivity to changes in this quantity of the order 10-6. Furthermore, the thickness of the films can

Research paper thumbnail of Nd doped KGW crystalline waveguides fabricated by pulsed laser deposition

... Author(s): Jan Lancok; Miroslav Jelinek; Jiri Oswald; Jiri Bulir; Peter A. Atanasov; Mihaela ... more ... Author(s): Jan Lancok; Miroslav Jelinek; Jiri Oswald; Jiri Bulir; Peter A. Atanasov; Mihaela E. Koleva; Ludovic Escoubas; Francois Flory. ... 4762. ALT'01 International Conference on Advanced Laser Technologies, Dan C. Dumitras; Maria Dinescu; Vitali I. Konov, Editors, pp.162-165. ...

Research paper thumbnail of <title>Structural and optical properties of PLZT thin films deposited by pulsed laser deposition</title>

11th International School on Quantum Electronics: Laser Physics and Applications, 2001

ABSTRACT

Research paper thumbnail of Consequences of the microstructure of thin films on their optical properties

SPIE Proceedings, 1994

Materials in thin film form are well known to have optical properties different from correspondin... more Materials in thin film form are well known to have optical properties different from corresponding bulk materials. The refractive index of films is smaller; their structure may be columnar and this induces water absorption-desorption phenomena, anisotropy and instabilities when illuminated with a high power light flux.

Research paper thumbnail of Optical anisotropy of thin-film materials measured with guided wave techniques

Annual Meeting Optical Society of America

Accurate measurements of coupling angles (m-lines method) corresponding to different propagation ... more Accurate measurements of coupling angles (m-lines method) corresponding to different propagation modes in a layer can reveal an optical anisotropy of the material constituting that layer. In the case of a layer obtained by evaporation condensation, this anisotropy can be directly correlated with the shape and the direction of the columns which are the main characteristics of the microstructure. Starting with the hypothesis of a birefringent structure with one of the optical axes oriented in the columnar growth direction, we have a calculation method for simultaneously determining the layer thickness and the indices corresponding to the principal axes. We show that the anisotropy depends in a critical way on the evaporation conditions: it is much marked when the layers have a more lacunar structure. And, for a coating made under oblique incidence, anisotropy increases with the angle of incidence. If the substrate is moved during deposition, the columnar growth is perturbed and anisot...

Research paper thumbnail of Interpretation of measurements of both losses on guided propagation and absorption from a model of absorbing transition layers

Optical Interference Coatings, 1994

ABSTRACT

Research paper thumbnail of <title>Utility of multidielectric coatings for realization of waveguides</title>

Optical Interference Coatings, 1994

The usefulness of multilayer optical coatings for realization of waveguides is discussed. Such gu... more The usefulness of multilayer optical coatings for realization of waveguides is discussed. Such guides are used to study the origin of losses. In particular it is shown that a model taking into account transition absorbing layers gives good explanation of the dispersion of the measured losses during propagation for the different guided modes. On the other hand a multilayer structure which could be efficiently coupled to a single mode optical fiber is presented.

Research paper thumbnail of Characterizations of thin films for optical microcomponents

Optical Interference Coatings, 2001

ABSTRACT

Research paper thumbnail of Thin films for optical systems

Research paper thumbnail of Optical Thin Films for Micro-Components

Springer Series in Optical Sciences, 2003

Research paper thumbnail of <title>Ion implantation in dielectric thin films for passive and active components</title>

Third International Conference on Thin Film Physics and Applications, 1998

ABSTRACT The consequences of Ti implantation in silica glasses and Ta2O5 layer are studied. It is... more ABSTRACT The consequences of Ti implantation in silica glasses and Ta2O5 layer are studied. It is shown that the optical losses can be low with a variation of the refractive index which can be well controlled. Results on rectangular waveguides and Y junctions are given. Erbium implanted Ta2O5 layers exhibit a luminescent behavior both in the green and in the infra-red. The emission diagram of the coating can be controlled with a multilayer structure.

Research paper thumbnail of Refractive index modifications and thermal properties of optical thin films with the prism coupler

Fourth International Conference on Thin Film Physics and Applications, 2000

The prism coupler can be used with a single beam to measure the refractive indices of isotropic o... more The prism coupler can be used with a single beam to measure the refractive indices of isotropic or anisotropic single layers and of layers in multilayer stacks with an accuracy of 1. X 10-3. The refractive index modification with temperature can also be measured easily. The refractive index of a thin film can also change under illumination. A two-beam set-up

Research paper thumbnail of Mesures de propriétés non linéaires thermiques de couches minces diélectriques

Optique instrumentale, 1997

Research paper thumbnail of <title>Enhancement of the diffraction efficiency of titanium implanted gratings by associating them with optical interference coatings</title>

Advances in Optical Interference Coatings, 1999

ABSTRACT Refractive index gratings made by titanium ion implantation are studied. Computations us... more ABSTRACT Refractive index gratings made by titanium ion implantation are studied. Computations using the rigorous differential method and otpical measurements show that our gratings implanted in SiO2 substrates have a diffraction efficiency of typically 2 percent in the 1st order. We propose to insert such grating in multilayer dielectric Fabry-Perot cavities in order to enhance the free space diffraction efficiency. Computations are performed by taking into account the index profile of the implanted zone. The best structure is obtained by optimizing the thickness of the implanted silica layer which is embedded between two mirrors. We study the dependence of optical properties of the structure with respect to various characteristic parameters such as the index profile, the multilayer design, the filling factor of the grating and the incident angle. To demonstrate the feasibility of such components, we focus our attention on an implanted grating embedded in a Fabry-Perot cavity whose mirrors have five dielectric layers. This component reaches a theoretical efficiency of 10 percent in the 1st order. First experimental results are presented.

Research paper thumbnail of Integrated Polarization Rotator and Splitter Made of Sputtered Ta<inf>2</inf>0<inf>5</inf> and Inorganic Silica Thin Films

2006 European Conference on Optical Communications, 2006

ABSTRACT Integrated polarization rotator and splitter, made with a new ridge waveguide technology... more ABSTRACT Integrated polarization rotator and splitter, made with a new ridge waveguide technology, have been simulated and realized with optical photolithography and lift off process. Experimental results show effective rotation and splitting with low cross-talk levels.

Research paper thumbnail of Is it opportune to study laser-induced damage of coatings by optical characterization?

SPIE Proceedings, 1999

High quality thin films completely free of defects is the goal for higher damage threshold but it... more High quality thin films completely free of defects is the goal for higher damage threshold but it remains a dream. Specific means of characterization to measure absorption losses by photothermal deflection and scattering losses are currently used. The analysis of experimental results permits to understand how the real behavior of thin films can be affected by localized defects. With the development of the mapping technique, the comparison between absorption and scattering intensity maps of the surface of coatings appears to be a good tool for this study. Moreover we need a more basic information concerning the multilayer under study and characterization by guided wave appears to be really fruitful. It permits the determination of the refractive index and the thickness of the different layers. Additional measurements of attenuation of guided waves can be used for the location of the absorption sites in the depth of the coating.

Research paper thumbnail of <title>Surface plasmon effect on metallic nanoparticles integrated in organic solar cells</title>

Optical Complex Systems: OCS11, 2011

Experimental results concerning the influence of plasmon effect from silver nanoparticles on the ... more Experimental results concerning the influence of plasmon effect from silver nanoparticles on the organic photovoltaic device performance are presented. The metallic nanoparticles (NPs) are placed on top of ITO layer using a physical vapor deposition technique. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) followed by an interpenetrated poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) blend layer are then spin-coated. The aluminum electrode is finally evaporated on.

Research paper thumbnail of Morphology and structure of TiO2 thin layers vs. thickness and substrate temperature

Thin Solid Films, 1989

Abstract TiO 2 thin layers are often used in multilayer coatings for optical filters and this mak... more Abstract TiO 2 thin layers are often used in multilayer coatings for optical filters and this makes their study especially interesting. Different TiO 2 thin layers corresponding to different thicknesses and deposited at different temperatures have been prepared by vapour deposition onto amorphous substrates. Most of these layers are amorphous but small crystals of anatase and rutile can also exist. These crystals are more frequent (i) if the substrate temperature is raised (350 °C) and/or (ii) if the thickness of the thin layer is higher. The surface roughness of TiO 2 thin layers has also been investigated by electron microscopy by two different and complementary methods: direct imaging by transmission electron microscopy and carbon-platinum replica observation. The thin layer surfaces are rather irregular, and this practically independently of the film thickness and of the substrate temperature during the deposition. Surface irregularities have been measured to reach about 10 nm. They have been shown to be slightly reduced on increasing the thin layer thicknesses from 35 to 70 nm. Each layer is made of blocks about 40 nm in size and each block is made of smaller blocks (about ten times smaller). The origin of this phenomenon has been sought. The formation of the smaller blocks is in agreement with existing theories of nucleation and growth of amorphous thin films. An attempt to find the origin of the larger blocks has also been carried out. This could be related to the permanent chemical transformation occuring during the thin layer formation. Finally, we relate the optical properties of the TiO 2 thin layers to their morphology and structure.

Research paper thumbnail of Gratings in resonant multilayer structures

Fourth International Conference on Thin Film Physics and Applications, 2000

Enhancement of the free-space diffraction efficiency of titanium-ion implanted gratings by insert... more Enhancement of the free-space diffraction efficiency of titanium-ion implanted gratings by inserting them into multilayer dielectric Fabry-Perot cavities has been demonstrated theoretically in previous works. In this paper, we discuss the sensitivity of the diffraction efficiency to the optogeometrical parameters of the structures obtained using titanium-ion implantation. A process to perform a phase grating in a seven-layer mirror Fabry-Perot cavity

Research paper thumbnail of Laser Deposition of Waveguiding Films

Nato Science Series

ABSTRACT

Research paper thumbnail of Wavelength and temperature dispersion of refractive index of thin films

Optical Complex Systems: Ocs11, 2011

The m-lines guided mode technique is demonstrated as a powerful tool for the measurement of wavel... more The m-lines guided mode technique is demonstrated as a powerful tool for the measurement of wavelength and temperature refractive index dispersion in thin films. The proper treatment of results reveals measurement uncertainties of the order of 10-3 for the refractive index, and a sensitivity to changes in this quantity of the order 10-6. Furthermore, the thickness of the films can

Research paper thumbnail of Nd doped KGW crystalline waveguides fabricated by pulsed laser deposition

... Author(s): Jan Lancok; Miroslav Jelinek; Jiri Oswald; Jiri Bulir; Peter A. Atanasov; Mihaela ... more ... Author(s): Jan Lancok; Miroslav Jelinek; Jiri Oswald; Jiri Bulir; Peter A. Atanasov; Mihaela E. Koleva; Ludovic Escoubas; Francois Flory. ... 4762. ALT'01 International Conference on Advanced Laser Technologies, Dan C. Dumitras; Maria Dinescu; Vitali I. Konov, Editors, pp.162-165. ...

Research paper thumbnail of <title>Structural and optical properties of PLZT thin films deposited by pulsed laser deposition</title>

11th International School on Quantum Electronics: Laser Physics and Applications, 2001

ABSTRACT

Research paper thumbnail of Consequences of the microstructure of thin films on their optical properties

SPIE Proceedings, 1994

Materials in thin film form are well known to have optical properties different from correspondin... more Materials in thin film form are well known to have optical properties different from corresponding bulk materials. The refractive index of films is smaller; their structure may be columnar and this induces water absorption-desorption phenomena, anisotropy and instabilities when illuminated with a high power light flux.