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This letter presents a simple technique that improves the symmetry of tapered fibers fabricated with a continuous-wave CO2 laser. The uniform heat distribution inside an optical fiber is achieved by using a nonscanning dual-spot laser beam which applies heat on two sides of the optical fiber simultaneously. In so doing, highly symmetric tapers are obtained with an ellipticity close to unity. These tapers can be used as low-loss and polarization-dependent loss optical fiber filters or other optical devices such as symmetric fibers lenses

We herein report the comparison of two independent reconstructions of the distribution of the /spl chi//sup (2)/ nonlinear susceptibility induced by thermal poling in planar silica samples. Both nonlinear profiles are quantitatively in good agreement in terms of /spl chi//sup (2)/ magnitude and nonlinear thickness; and qualitatively in agreement in terms of shape. We conclude that both characterization methods used are efficient for the determination of the /spl chi//sup (2)/ susceptibility spatial distribution in bulk samples.

This paper presents recent scheme based of direct dual wavelength laser writing of lightwave circuits developed in our laboratories. The system allows the fabrication of features of the order of ~1 micron by using a short wavelength laser to ablate a region preheated by a second laser.

A reflectance measurement technique was used to determine the refractive index distribution of optical waveguides fabricated by a CW CO 2 direct writing technique. The uniformity of refractive index has been verified along the waveguides structure and used as input for accurate beam propagation method (BPM) calculations of waveguide devices.

This paper presents recent research undertaken in our laboratory in the field of direct laser writing of microfluidics circuits. Our novel technology allows the rapid fabrication of complex fluidic circuits. The fabricated channel have smooth walls and surfaces enabling the encapsulation of the circuits.

This invited talk presents the most recent work undertaken in our laboratory in the fields of direct laser writing of planar optical integrated circuits, laser written micro fluidics circuits, laser machining of v-grooves and laser machining in diffraction gratings.

Thermal poling of Suprasil 300™ silica glass samples is performed at temperatures up to 800°C. The cathodic current measured during poling shows that significant charge injection occurs. Measurements of the X(2) susceptibility by the Maker fringes technique are shown.

An experimental setup is proposed to obtain the phase of the second-harmonic generated signal when performing Maker fringe measurements. This phase information is useful for the reconstruction of X(2)(z) profiles.

We have developed a 2 layer Laser-Ultrasonics model with interfacial conditions that describes the cohesion of materials. Different materials made with Schott’s BG18 and KG3 glass plates glued on aluminum plates were studied. Our model allows us to fit nicely the experimental results: the reflections coming from the interfacial medium are seen giving us information on the bonding of the two plates.

A new nondestructive characterization technique, based on a modified Maker fringe measurement, is reported that allows the complete determination of complex spatial distributions of the nonlinear χ(2)(z) coefficient in planar samples. Each sample under test was stacked together with a phase reference quartz plate to retrieve both amplitude and phase of the optical second-harmonic signal. The added phase information permits the precise determination of the location of the optically nonlinear region within the sample. Hemicylindrical lenses are used to obtain greater internal propagation angles, with an important increase in the information about the nonlinearity distribution. The technique is demonstrated for two Infrasil glass plates thermally poled in vacuum under the same temperature, voltage, and duration conditions. Very different distributions were obtained for these samples, one nonlinear layer being buried 4 μm under the anodic surface while the other was not, the latter exhibiting maximum χ(2) three times larger than the former. This difference in the χ(2)(z) distribution is explained in terms of charge injection during the poling process.