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An extensive characterization of the photorefractive bright soliton writing process in a lithium niobate crystal is presented. An interferometric approach based on a digital holographic technique has been used to reconstruct the complex wave field at the exit face of the crystal. Temporal evolution of both intensity and phase profile of the writing beam has been analysed. The effective changes of the refractive index of the medium during the writing process and after the soliton formation are determined from the optical phase distribution. This method provides a reliable way to observe the process of soliton formation, whereas the determination of the intensity distribution of the output beam does not show clearly whether the soliton regime has been achieved or not. Furthermore, a detailed analysis of the soliton in a steady-state situation and with different writing conditions is presented and discussed.

In recent years a variety of liquid bases optical elements have been conceived, designed and fabricated even for commercial products like digital cameras o cellular phone cameras. The impressive development of microfluidic systems in conjunction with optics has led to the creation of a completely new Science field of investigation named optofludics. Optofludics, among others topics, deals with investigation and methods for realizing liquid micro-lenses. A variety of liquid micro-lenses have been designed and realized by using different configurations. We demonstrate that a lensing effect can be obtained in an open microfluidic system by using a thin layer of liquid on a polar electric crystal such as Lithium Niobate (LiNbO3). Electrowetting patterning on LiNbO3 surface is obtained by pyroelectric effect consisting in a simple but reliable electrodes-less and circuit-less configuration. The electrodes are intrinsically embedded into the substrate. The material is functionalised by means of a micro-engineering electric filed poling process. Lens array with variable focus has been demonstrated with a large number of lens elements (10x10) on micrometric scale (aperture of single lens 100 microns).

Resolution is an important issue in inspection of objects on microscopic scale. Various approaches have been investigated to increase the optical resolution behind the diffraction limit of an optical imaging system. Demonstration that super-resolution is possible have been also established in interference microscopy. We have studied the possibility to use diffraction gratings, in different experimental configurations for increasing the aperture of an optical imaging system. The aim of the study is to demonstrate that super-resolution is possible and is a practical and viable method for a coherent optical microscope. We take benefit of the numerical reconstruction properties of DH in combination with diffraction grating to get super-resolution. Various attempts have been performed and results are presented and discussed. The approaches could be used for metrology and imaging application in various fields of engineering and biology.

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We present an adaptive and dynamic hexagonal electro-optic phase array. The proposed device consists of a 2-dimensional hexagonal array of periodically inverted ferroelectric domains, along the z-axis, in lithium niobate crystals. The phase step is achieved via the application of an external electric field, along the z-axis, through transparent electrodes. Thanks to the electro-optic effect the phase step can changed with continuity over all the 0 to 2 by applying a variable voltage. In this way different patterns can be generated. In fact, one important property of this new proposed configuration of array iluminator is the intrinsic flexibility.

We report on the fabrication and characterization of periodic nanoscale one- and two-dimensional surface structures in congruent 500 µm thick lithium niobate crystal samples. Structures with periods from 2 µm down to around 500 nm, lateral feature sizes down to 200 nm and depths compatible with conventional waveguide fabrication, have been obtained. Such structures are fabricated by applying polarity selective etching to periodically domain reversed samples obtained by electric field poling performed by overpoling regime. Holographic lithography is used to obtain sub-micron periodic insulating gratings to be used for selective ferroelectric domain reversal. The short pitch structures are attractive in a wide range of applications ranging from nonlinear optics, for short-wavelength conversion processes or backward second-harmonic generation, to the field of photonic crystals to fabricate novel tunable photonic crystal devices or electro-optically modulated Bragg gratings. Moreover moire beating effect is used in the photolithographic process to fabricate even more complex structures which could find applications in complicated photonic bandgap devices involving for example micro-ring resonators. In order to investigate the possibility to utilize these structures for photonic crystal applications, accurate topography characterization has been performed by using different techniques. Atomic force microscope provides high-resolution information about the lateral and depth feature size of the structures, while interferometric techniques, based on digital holography, have been used for wide field information about the homogeneity and periodicity of the structures.

We realized one and two dimensional periodic ferrolectric domain structurure obtained by an electric- field poling process applied to 500 microns thick lithium niobate crystal samples patterned by means interference litography

Ferroelectric domain micro structuring of bulk lithium Niobate is very useful for optoelectronic applications such as non-linear optic employing Quasi-Phase-Matching for efficient harmonic and parametric conversion processes. We report on the application of digital holography as metrological tol for the inspection and characterization of the domain structures in bulk lithium niobate samples

Very interesting effects can be observed in maneuvering nematic liquid crystal (NLC) droplets onto functionalized polar lithium niobate (LN) crystal surfaces, covered with thin films of Polydimethylsiloxane (PDMS). It has been discovered that pyroelectric effect is able to drive a reversible fragmentation process in liquid crystal drops, starting from nanoliter drops and obtaining pico/femtoliter droplets. These small droplets are patterned according to the geometry of the substrate and aligned along the electric field lines. This novel approach for manipulating different classes of liquids by exploiting the pyroelectric effect, where the strong electric fields generated allow to manipulate liquids in 2D on a substrate or even in 3D, has been recently discovered and exploited for different purposes. In particular, manipulation of liquid crystals by a thermal stimulus could be suitable for applications such as spatial modulation of the wettability (i.e. wettability patterning), or, in principle, a dynamical optical element able to switch from a diffuser (fragmentation) state to a microlens array. Moreover, the biocompatibility of some kinds of nematic or cholesteric liquid crystals makes them suitable as biomaterials for applications in biology and tissue engineering.