Abstract: An integrated optical waveguide device comprises: a substrate (10) of a ferroelectric material; at least one waveguide (13;13A,13B) integrated in the substrate in correspondence of a surface (11) thereof; at least a longitudinal section (13;131,132,133;13A,13B) of the at least one waveguide is formed in a respective first substrate region (14;141,142,143;14A,14B;140A,140B;140C,140D) having a first orientation of spontaneous polarization. The first substrate region is sandwiched between at least two second substrate regions (15,16;151,161,152,162,153,163;15A,15B,17A,17B,16A,16B;150,1 60) which have a second orientation of spontaneous polarization, opposite to the first orientation, and are located at opposite sides of the waveguide section with respect to a longitudinal direction thereof.

Abstract: A system based on integrated optical technologies for the measurement and diagnostics of physical parameters on whatever structure, by the use of optical sensors, made by the fiber embedded Bragg grating method and by the use of a planar integrated optics device for the analysis of the optical signal. The sensors may be embedded or bonded to the structure, allowing the measurement of parameters like strain and temperature, in either a static or dynamic regime. The system pertains to the technical field of the diagnostics and measurements of mechanical or thermal parameters and to the application field of ground, water and aerospace transportation and also to the application field of construction.

Abstract: An embedded optical sensor has a plurality of layers 10-20 and an optical fiber 21 with a fiber grating 28, disposed between the layers 14,16. The layers 10-20 comprise filaments 22 and resin 24 which have different thermal expansion coefficients and the filaments 22 are oriented so as to create unequal transverse residual stresses that act through the geometry of a resin-rich region that surrounds on the grating 28 in the fiber 21. The unequal transverse residual stresses cause birefringence in the grating 28, thereby causing the grating 28 to reflect light 32 having two wavelengths with a predetermined separation, each along a different polarization axis. The wavelength separation and average wavelength between such separation have different sensitivities to temperature and strain, thereby allowing independent temperature and strain measurements using only a single grating.

Abstract: A manufacturing process for high performance single mode channel optical guides of the LiNbO.sub.3 using five successive steps: photo-etched optical path definition, deposition of the dielectric layer, lift-off definition of the channels, proton exchange and thermal cycling. The method can be used to produce multi-function devices to be interfaced with optical fibers to obtain sensors, telecommunications devices and devices for processing wide-band microwave signals the proton exchange is affected in benzoic acid diluted with lithium benzoate and eliminates the time instability of the electro-optical structure due to the presence of an insulating layer above the optical guide.

Abstract: Lithium niobate is Li.sup.+ /H.sup.+ proton exchange in two stages. The first masked stage is a treatment with benzoic acid followed by a thermal treatment in oxygen at about 400.degree. C. The thermal treatment is followed by masking a second coincident area and treating that area in a second Li.sup.+ /H.sup.+ proton exchange with benzoic acid and lithium benzoate without altering the refractive index of the region outside the second area.