Abstract: The invention is based on a process and system for producing random numbers by means of a quantum random number generator where the method comprises the steps of operating a laser in single mode and high modulation bandwidth by means of an electrical pulse driver, transforming the phase randomized optical pulses produced before in optical pulses with random amplitude and detecting the resulting random amplitude signals by means of a fast photodiode. The numbers thus produced are truly random.

Abstract: Disclosed is an electrode that includes a substrate and a layered structure having an electrically conductive film in contact with at least one ultra thin metal film, wherein the two films are of different materials and the electrically conductive film is one of Cu, Au, Ag, Al and the ultra thin metal film is one of Ni, Cr, Ti, Pt, Ag, Au, Al and their mixtures. The electrode is particularly useful for optoelectronic devices and shows good conductivity, transparency and stability.

Abstract: The present invention relates to a transparent electrode comprising an ultra thin metal conductor (2) with a thickness between 1 nm and 10 nm and a metal grid in contact with the ultra thin metal conductor (3), the metal grid comprising openings. The invention relates also to a method for its manufacture. It can be applied in, for example, optoelectronic devices. Thanks to the metal grid, the sheet resistance of the electrode can be lowered without compromising the transparency of the electrode.

Abstract: The present application discloses a method for producing a stable ultra thin metal film that comprises the following steps: a) deposition, on a substrate, of an ultra thin metal film, such as an ultra thin film of nickel, chromium, aluminium, or titanium; b) thermal treatment of the ultra thin metal film, optionally in combination with an O2 treatment; and c) obtaining a protective oxide layer on top of the ultra thin metal film.

Abstract: A compact and stable interferometer is easily built only with fusion splices. The air-holes of a microstructured fiber are intentionally collapsed in the vicinity of the splices and this broadens the propagating optical mode, allowing coupling from core to cladding modes. The transmission spectrum is sinusoidal and of single frequency, indicating predominant interference between the fundamental core mode (7) and a cladding mode (6). A regular interference spectrum can be observed from 650 nm to 1600 nm with fringe visibility reaching 80%. The fringe spacing is inversely proportional to the distance between the splices. This behavior has a significant impact in optical sensing and communications and so the interferometer can be applied for strain sensing. The device comprises two splices (5) of a microstructured optical fiber (1), said splices (5) determining two regions in which the air-holes (4) are collapsed, separated a length (L) along which said two modes are excited.

Abstract: A compact and stable interferometer is easily built only with fusion splices. The air-holes of a microstructured fiber are intentionally collapsed in the vicinity of the splices and this broadens the propagating optical mode, allowing coupling from core to cladding modes. The transmission spectrum is sinusoidal and of single frequency, indicating predominant interference between the fundamental core mode (7) and a cladding mode (6). A regular interference spectrum can be observed from 650 nm to 1600 nm with fringe visibility reaching 80%. The fringe spacing is inversely proportional to the distance between the splices. This behaviour has a significant impact in optical sensing and communications and so the interferometer can be applied for strain sensing. The device comprises two splices (5) of a microstructured optical fiber (1), said splices (5) determining two regions in which the air-holes (4) are collapsed, separated a length (L) along which said two modes are excited.

Abstract: A method and structure are disclosed with a simplified approach for fabricating a LiNbO3 wafer with Ti indiffusion wafeguide on the surface that is domain inverted. The method involves indiffusing Ti into LiNbO3 with a predefined temperature and time indiffusion range, a Li enriched and dry oxygen atmosphere, which allows making optical waveguides on the z? crystal face without any significant domain inversion occurring on the z+ face of the crystal. This allows for subsequent poling without the need of any additional removal of the thin domain inverted layer which would otherwise appear on the z+ face. Even in instance where a thin domain inversion layer is formed, it is insufficient thick to prevent poling, eliminating the need for the grinding process.

Abstract: Accordingly, a preferred embodiment of the present invention comprises an electro-optical device having an optical waveguide that includes two optical pathways, wherein the optical waveguide is embedded within the substrate. A bias electrode layer is formed on the surface of the substrate. A buffer layer is formed on at least a portion of the bias electrode layer and the surface of the substrate. An RF electrode layer is formed on the buffer layer. A bias-tee electrically couples the bias electrode layer and the RF electrode layer.

Abstract: Accordingly, a preferred embodiment of the present invention comprises an electro-optical device having an optical waveguide that includes two optical pathways, wherein the optical waveguide is embedded within the substrate. A bias electrode layer is formed on the surface of the substrate. A buffer layer is formed on at least a portion of the bias electrode layer and the surface of the substrate. An RF electrode layer is formed on the buffer layer. A bias-tee electrically couples the bias electrode layer and the RF electrode layer.

Abstract: An electro-optical device capable of modulating the amplitude or phase of an optical output in response to an electrical data or control signal, or of switching it, has reduced frequency-dependence and a better combination of operating voltage and bandwidth. It comprises a body of electro-optically active material, waveguides for passing light through the body, and electrodes for applying an electric field with a frequency in the microwave region to the body, and its transverse geometry is such as to maintain adequate phase velocity matching between optical and microwave frequencies. There is a discontinuity in either the body or at least one of the electrodes such that the direction of the electro-optic effect is reversed for a portion of the length of the device at or near its downstream end.

Abstract: A method and structure are disclosed with a simplified approach for fabricating a LiNbO3 wafer with Ti indiffusion wafeguide on the surface that is domain inverted. The method involves indiffusing Ti into LiNbO3 with a predefined temperature and time indiffusion range, a Li enriched and dry oxygen atmosphere, which allows making optical waveguides on the z? crystal face without any significant domain inversion occurring on the z+ face of the crystal. This allows for subsequent poling without the need of any additional removal of the thin domain inverted layer which would otherwise appear on the z+ face. Even in instance where a thin domain inversion layer is formed, it is insufficient thick to prevent poling, eliminating the need for the grinding process.

Abstract: A conversion method for converting a unipolar voltage data stream into a carrier-suppressed return-to-zero (CSRZ) optical data stream includes modulating a continuous optical wave with an encoded nonreturn-to-zero (NRZ) voltage data stream for providing a CSRZ optical data stream of full-width at half-maximum (FWHM) pulse width less than one-half of the transition time of the encoded nonreturn-to-zero (NRZ) voltage data stream between logical states for a reduced pulse width. The modulating circuit is either a duobinary modulator driven with a swing of ±2V? or an optical time domain multiplexed plurality of nonreturn-to-zero (NRZ) modulators with phase shifting and differential encoding.

Abstract: A method of creating a varying second order non-linearity profile along a waveguide, comprising: providing a waveguide structure with a waveguiding core and a surface adjacent to the waveguiding core; structuring the surface to produce a structured surface defining a varying distance between the structured surface and the waveguiding core along the waveguide; and thermally poling the waveguide structure to generate a varying second order non-linearity profile along the waveguide-derived from the varying distance between the structured surface and the waveguiding core. By the surface structuring the modulation of the second order non-linearly induced by the thermal poling can be enhanced. The waveguide structures can be used for making a variety of quasi-phase-matched (QPM) devices.

Abstract: A conversion method for converting a unipolar voltage data stream into a carrier-suppressed return-to-zero (CSRZ) optical data stream includes modulating a continuous optical wave with an encoded nonreturn-to-zero (NRZ) voltage data stream for providing a CSRZ optical data stream of full-width at half-maximum (FWHM) pulse width less than one-half of the transition time of the encoded nonreturn-to-zero (NRZ) voltage data stream between logical states for a reduced pulse-width. The modulating circuit is either a duobinary modulator driven with a swing of ±2V&pgr; or an optical time domain multiplexed plurality of nonreturn-to-zero (NRZ) modulators with phase shifting and differential encoding.

Abstract: An optical parametric device for broadband parametric processes involving first and second frequencies &ohgr;1 and &ohgr;2. The device comprises an optical fiber comprising a core and a cladding, the cladding being microstructured with holes for providing waveguiding confinement of at least one optical mode in the core. The optical fiber is poled lengthwise with a non-linearity profile having a period that satisfies a quasi phase matching (QPM) condition including the first and second frequencies. Through the use of a poled holey fiber of suitable hole structure, it is possible to increase the second harmonic (SH) efficiency in comparison with poled conventional (non-holey) fiber. This is achieved by a combination of a low mode overlap area between the fundamental and SH waves, a low absolute value of the mode area, and a large SH bandwidth per unit length of the fiber, all of which can be provided together in a poled holey fiber.

Abstract: A coplanar integrated optical waveguide electro-optical modulator comprises a substrate (1) of an electro-optic material, at least two optical waveguides (41, 42) integrated in the substrate in correspondence of a surface (71) thereof, and an electrode system (80, 90, 100; 80, 90, 900; 12-15; 120, 130, 140, 150, 160, 170) arranged on the surface for applying a modulating electric field to the waveguides suitable for causing a modulation of a refractive index of the two waveguides in a device modulation region (50). The waveguides are formed, for at least a section thereof (411, 421) in the device modulation region, in respective substrate regions (61, 62) which have electro-optic coefficients of opposite sign along an axis transversal to the waveguide sections, so that a modulating electric field of same direction and orientation in the waveguide sections causes refractive index modulations of opposite sign in the waveguide sections.

Abstract: A method of and apparatus for creating a second order non-linearity profile along a waveguide. The method comprises: thermally poling a waveguide structure to generate a second order non-linearity; placing a mask adjacent to the waveguide structure; and exposing the waveguide structure with UV light through the mask to selectively erase the second order non-linearity along the waveguide structure. The mask may be an amplitude mask or phase mask. In a preferred embodiment an amplitude mask is used in combination with an incoherent UV light source to produce selective erasure of a thermally poled second order non-linearity. Apparatus for carrying out this method and devices based on waveguide structure fabricated using the method are also described.

Abstract: An electro-optical device capable of modulating the amplitude or phase of an optical output in response to an electrical data or control signal, or of switching it, has reduced frequency-dependence and a better combination of operating voltage and bandwidth. It comprises a body of electro-optically active material, waveguides for passing light through the body, and electrodes for applying an electric field with a frequency in the microwave region to the body, and its transverse geometry is such as to maintain adequate phase velocity matching between optical and microwave frequencies. There is a discontinuity in either the body or at least one of the electrodes such that the direction of the electro-optic effect is reversed for a portion of the length of the device at or near its downstream end.

Abstract: Optical waveguides having a waveguide channel of photosensitive silica glass with a modified refractive index optically written therein, wherein the photosensitive glass comprises oxides of silicon, tin and at least one Group I element, where such optical waveguide devices include optical fiber gratings, optical fiber dispersion compensators, optical fiber sensors, optical fiber lasers, and planar waveguide devices.

Abstract: A photosensitive glass made of a ternary compound SiO2:SnO2:R2O where R is a Group I element such as Na, K or Li. The addition of an oxide of a Group I element increases the solubility of tin oxide in a silica matrix and produces a glass which is highly photosensitive and in which optically written refractive index modulations have remarkable temperature stability (solid circles) at least as good as that of the binary glass SiO2:SnO2 (open circles) and much superior to that of conventional germanosilicate glass (solid triangles) or borogermanosilicate glass (open triangles). The inclusion of the Group I oxide effectively increases the solubility of tin oxide in the non-crystalline silica matrix well above the 1% limit of SiO2:SnO2 photosensitive glass, at which Sn would normally crystallize in the oxide.