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We have investigated the influence of the poly(3,4-ethylenedioxythiophene)-blend-poly(styrene-sulfonate) (PEDOT:PSS) layer on the short-circuit current density ([J.sub.sc]) of single planar heterojunction organic solar cells based on a copper phthalocyanine (CuPc)-buckminsterfullerene ([C.sub.60]) active layer. Complete optical and electrical modeling of the cell has been performed taking into account optical interferences and exciton diffusion. Comparison of experimental and simulated external quantum efficiency has allowed us to estimate the exciton diffusion length to be 37 nm for the CuPc and 19 nm for the [C.sub.60]. The dependence of short-circuit current densities versus the thickness of the PEDOT:PSS layer is analyzed and compared with experimental data. It is found that the variation in short-circuit current densities could be explained by optical interferences. OCIS codes: 040.5350, 160.4890.

The optogeometric properties of various sensitive thin films involved in gas sensing applications are investigated by using the m-line technique and atomic force microscopy. Variations of these optical properties are studied under butane and ozone exposure. OCIS codes: 310.2790, 310.6860.

The calculated spectral transmittance of a multilayer laser mirror is used to determine the effective index of the single layer equivalent to the multilayer stack. We measure the artificial anisotropy of photoresist thin films whose structure is a one-dimensional, subwavelength grating obtained from interference fringes. The limitation of the theory of the first-order effective index homogenization is discussed. We designed normal-incidence, polarizing coating and a polarization rotator by embedding anisotropic films in simple multilayer structures. OCIS codes: 260.1440, 050.1950.

A pump-and-probe setup that uses a totally reflecting prism coupler is presented. Its electromagnetic and thermal models are described. To our knowledge, the first results are given concerning the measurement of thermal properties of thin films. OCIS codes: 120.6810, 310.2790.

Measurements of [differential]n/[differential]T of thin films by the m-lines technique are presented. The importance of the substrate material is shown. An example of the wavelength shift of an optical thin-film filter with temperature is studied both theoretically and experimentally. The theoretical wavelength shift of a dense wavelength-division multiplexing filter is discussed. OCIS codes: 310.6860, 350.2460.

The design of integrated optics filters by use of refinement software based on the Abeles thin-film computation method and the film mode matching method is studied. The results obtained with the two computation methods are compared. Good agreement is obtained provided that the fill factor of the guided mode in the component is high and that modal losses between waveguide sections are simulated by absorption with the Abeles computation method. Integrated optics devices that manage either the amplitude of guided waves such as a dense wavelength division multiplexing narrow-bandpass filter and a gain-flattening filter or the phase of guided waves such as a broadband dispersion compensator are presented and their optical performance is discussed. OCIS codes: 230.7390, 130.3120, 130.1750.

The m-lines technique is used to measure the refractive indices and thicknesses of layers embedded in a multilayer stack. The multilayer considered is deposited by ion plating. Its formula is silica - 4H-L 4H-L-6H-air, where H and L denote [Ta.sub.2][O.sub.5] and Si[O.sub.2][Lambda]/4 layers, respectively, with [Lambda] = 514.5 nm. Measurements indicate that the refractive index of [Ta.sub.2][O.sub.5] is 5 x [10.sup.-3] greater when the layer is close to air than when the layer is inside the coating and that the [Ta.sub.2][O.sub.5] is slightly more birefringent.

Research was conducted to examine bulk and thin film amorphous silica embedded with titanium by studying the induced modifications of the microstructure and the results on optical features. Titanium distribution was inversely correlated with the refractive index profile. Results showed that the implanted materials exhibited low optical losses during thermal annealing They also indicated that the implanted bulk silica was characterized by a grain structure with microcrystals.

Starting with an accurate linear electromagnetic theory of a totally reflecting prism coupled to a dielectric waveguide, we implement a numerical technique to take into account optogeometric perturbations in stratified media. We calculate both the reflected fields in intensity on the prism base (near field) and in infinity (far field) for an incident Gaussian beam. The study of the variations of the intensity in the reflected beam (near and far fields) versus light power shows thermoinduced dilation of the prism and an intensity-dependent refractive index of thin films composed of tantalium pentoxyde and titanium dioxide. Key words: Intensity-dependent refractive index, thermal effect, prism coupler, dielectric thin films, guided wves.

We study the reversible refractive index variations of optical thin films submitted to a high-power light flux. As a preliminary step, we study the thermorefractive coefficient curly d n/curly d T and the laser damage threshold of our materials. From the hypothesis of a localized optical Kerr-type effect, we use the m-line technique to estimate the nonlinear refractive-index coefficients n(sub 2) of TiO2, Ta2O5, and ZnS films with continuous illumination. Very large values of n(sub 2) are found for the films obtained by conventional evaporation condensation. On the other hand, the study of the change in the decoupling direction of a low-power light guided in a layer disturbed by a pulsed YAG laser gives a first analysis of the phenomena versus time.

The main purpose of this research is to study the anisotropic behavior of dielectric material in thin-film form. First we present a theory based on a 4 X 4 transfer matrix linking tangential components of the electromagnetic field on one interface to the tangential components of the electromagnetic field on the other interface of an anisotropic thin film. A biaxial model is associated with the columnar structure of the layer. The comparison between measurements of the transmission in normal incidence in cross-polarized light and of guided-mode propagation constants with the calculations allows us to study the biaxial behavior of TiO2 films. The excellent consistency between measurements and computations demonstrates the validity of the model based on the columnar structure.

Enhancement of the free-space diffraction efficiency of gratings made by titanium-ion implantation is demonstrated both theoretically and experimentally. Indeed, by insertion of a grating into a multilayer dielectric Fabry-Perot cavity, the diffraction efficiency can be increased to as much as 24 times that of a single grating. The sensitivity of the diffraction efficiency to the optogeometrical parameters of the grating or of the Fabry-Perot cavity is discussed. Moreover, a process for performance of a phase grating inside a Fabry-Perot cavity is described, and experimental results concerning efficiency measurements are compared with computed values for various grating periods. [C] 2001 Optical Society of America OCIS codes: 050.1950, 050.1970, 050.2230.