Abstract: The present invention proposes optical fiber equipment having a Bragg grating tunable by a piezoelectric actuator, the equipment comprising an optical fiber, a Bragg grating photoinduced in said fiber, a support for supporting said fiber and comprising two uprights at opposite ends of said Bragg grating, each upright having a first holding element for holding said fiber, and a piezoelectric actuator held via its ends between the two uprights, said actuator being longitudinally prestressed in compression between said uprights.

Abstract: The present invention relates to a fiber grating filter optical waveguide device, comprising an optical fiber with an optical filter, both consisting essentially of silica, whereby said optical filter has an area with a grating region, wherein said area with a grating region is covered with a layer comprising a material having a refractive index which is the same or higher than the refractive index of the material of the optical fiber. The variation of the physic-chemical nature of said material allows to match the changes in the refractive index of the optical fiber of the optical filter when specific requirements for a high transmission spectrum of the filter are required.

Abstract: The present invention relates to a Bragg grating filter optical waveguide device, comprising an optical fiber provided with a Bragg grating region which is externally strained to alter the range of chirping. The external strain is induced by a gradient-generating mechanical body bonded onto the length of the fiber grating.

Abstract: An optical filter (20) composed of a concatenation of elementary filters (10) consisting of chirped slanted Bragg gratings written on a continuous portion of an optical waveguide, characterised in that the various gratings in the concatenation have the same angle, identical lengths and a linear chirp.

Abstract: A tuneable optical fibre comprising a long-period Bragg grating (5) written in a portion of an optical waveguide (10) comprising a core and an optical cladding (11), characterised in that the portion of the waveguide comprising the grating (5) is at least partially immersed in an external environment consisting of two distinct sections, a first section (1) whose refractive index is higher than that of the optical cladding (11) and a second section (2) whose refractive index is lower than that of the optical cladding (11), the long-period grating being at least partially immersed in one of the said sections so as to almost independently tune the wavelength and/or the contrast of the spectral response of the filter.

Abstract: The invention relates to compensating chromatic dispersion and chromatic dispersion slope in optical fiber transmission systems. It proposes using dispersion compensating fiber (12) and a plurality of Bragg gratings (15, 16, 17) for compensating chromatic dispersion in the transmission fiber (4i). Each Bragg grating presents a bandwidth that is greater than 25 nm, so as to enable the system to be used in broad bands. In addition, the absolute value of the compensation provided by each Bragg grating is less than 250 ps/nm, thus ensuring that the grating remains easy to manufacture in spite of its broad band. The invention applies in particular to very high data rate systems (above 40 Gbit/s for each channel), with a utilization band extending between 1250 nm to 1650 nm.

Abstract: An optical mode converter comprising an optical guide able to transmit an optical signal in at least one guided mode, characterised in that the optical guide comprises a photosensitive zone inducing a specific index profile along a section of the guide, the said index profile simultaneously defining a longitudinal adiabatic transition and a transverse distribution of the guided mode or modes so as to deconfine the fundamental mode and to maximise the overlap with a higher-order mode.

Abstract: An optical filter includes a coupler having n output branches and an input branch receiving an input signal whose spectrum comprises a comb of wavelengths periodically spaced by a spacing eP. Each of the n output branches is coupled to a waveguide including two or more cascaded copropagated coupling components. Each of the n branches produces an output signal whose spectrum comprises a comb of wavelengths periodically spaced by a spacing equal to n times the spacing eP. Each of the n output signal spectra is complementary to the others.

Abstract: The invention concerns a tunable filter comprising an optical fiber incorporating a Bragg grating on a portion of the fiber. Said fiber portion is coated with a material retained within a confined space and adapted to exert pressure on said Bragg grating to compress said portion of fiber radially and to stretch it longitudinally.

Abstract: The invention relates to polarization mode dispersion; writing index variations in a grating written in an optical fiber generates polarization mode dispersion. The invention proposes to compensate this polarization mode dispersion by mechanical curvature of the fiber. The invention provides a simple method of compensating polarization mode dispersion effectively and improving the performance of a grating written in a fiber; it applies in particular to Bragg gratings.

Abstract: The present invention relates to the field of optical fiber telecommunications. More specifically, the subject of the invention is a slanted Bragg grating optical fiber and a process for manufacturing such a fiber. The slanted Bragg grating optical fiber of longitudinal axis Z has slanted Bragg gratings photowritten in said fiber and having refractive index modulations along said axis Z, inclined at a same writing angle with respect to a normal plane to said axis Z and defining planes called writing planes forming the same angle than the writing angle with said normal plane, each writing plane forming with others writing planes specific angles called angles of rotation about said axis Z.

Abstract: The present invention relates to a chromatic dispersion compensator comprising a Bragg grating with quadratically varying pitch, said Bragg grating having a group time response with a quadratic component Q1 and a linear component L1, and the compensator further comprising a Bragg grating with linearly varying pitch, said Bragg grating with linearly varying pitch having a group time response with a linear component L2, and said linear components L1 and L2 being opposite in sign.

Abstract: A system for compensating chromatic dispersion includes a long variable pitch Bragg grating written in an optical fiber in which wavelength division multiplexed transmission channels propagate. A system for generating a thermal gradient includes at least two heating systems distributed over the grating and controlled independently of each other to compensate simultaneously the chromatic dispersion on a plurality of transmission channels.

Abstract: The present invention proposes optical fiber equipment having a Bragg grating tunable by a piezoelectric actuator, the equipment comprising an optical fiber, a Bragg grating photoinduced in said fiber, a support for supporting said fiber and comprising two uprights at opposite ends of said Bragg grating, each upright having a first holding element for holding said fiber, and a piezoelectric actuator held via its ends between the two uprights, said actuator being longitudinally prestressed in compression between said uprights.

Abstract: The invention relates to an optical fiber presenting a core, cladding, and a grating written by irradiation and coupling at least one light mode into the cladding so that it is dissipated therein. The invention proposes causing the mean index to vary progressively along the grating, at least at the ends of the grating. The progressive variation in mean index or in the amplitude of index modulation for writing the grating serves to limit insertion losses to the filter formed by the grating. Analogously, in a written-in grating, the invention provides the equivalent of progressively varying the core size of the fiber for interconnecting two optical fibers presenting different core diameters. The invention is applicable in particular to gain-equalizing filters in WDM transmission systems.

Abstract: A method for imprinting a plurality of slanted Bragg gratings into a photosensitive optical fiber by exposure of said fiber to a pattern of light shaped in space and/or time and of suitable wavelenth is presented. According to the invention a basic slanted Bragg grating of a determined period is imprinted into said fiber, while, simultanously, a periodic apodisation function is applied to said single slanted Bragg grating. In its preferred embodiment the imprinting light pattern is generated by a phase mask from a UV laser, the phase mask being dithered during the imprinting.

Abstract: The invention is related to an optical waveguide device comprising

Abstract: The present invention relates to a Bragg grating filter optical waveguide device, comprising an optical fiber provided with a Bragg grating region which is externally strained to alter the range of chirping. The external strain is induced by a gradient-generating mechanical body bonded onto the length of the fiber grating.

Abstract: The present invention relates to a temperature compensating device for a prestrained fiber grating of an optical fiber, wherein said device comprises a body with a substantially cylindrical form and wherein the fiber grating is wound up on said body, whereby the dimensions of said body vary according to a change in temperature. The temperature compensating devive according to the invention is athermal and allows a tunig of the wavelength of the fiber grating.

Abstract: The invention relates to polarization mode dispersion; writing index variations in a grating written in an optical fiber generates polarization mode dispersion. The invention proposes to compensate this polarization mode dispersion by mechanical curvature of the fiber. The invention provides a simple method of compensating polarization mode dispersion effectively and improving the performance of a grating written in a fiber; it applies in particular to Bragg gratings.