Abstract: An underwater connection assembly comprises an underwater device and an optical cable segment. The optical cable segment is configured to be coupled to a first sea earth by means of a first sea earthing electrode and the underwater device is configured to be coupled to a second sea earth by means of a second sea earthing electrode. In use, the first sea earthing electrode and the second sea earthing electrode are disposed at separated locations from each other.

Abstract: An underwater connection assembly comprises an underwater device and an optical cable segment. The optical cable segment is configured to be coupled to a first sea earth by means of a first sea earthing electrode and the underwater device is configured to be coupled to a second sea earth by means of a second sea earthing electrode. In use, the first sea earthing electrode and the second sea earthing electrode are disposed at separated locations from each other.

Abstract: The fibre is adapted to compensation of the chromatic dispersion and chromatic dispersion slope of an optical fibre with negative chromatic dispersion. It has, in a propagation mode other than the fundamental mode, a positive chromatic dispersion and a negative chromatic dispersion slope. The fibre can be used in compensation dispersion modules or as line fibre, in transmission systems using line fibre with negative chromatic dispersion.

Abstract: The fiber is adapted to compensation of the chromatic dispersion and chromatic dispersion slope of an optical fiber with negative chromatic dispersion. It has, in a propagation mode other than the fundamental mode, a positive chromatic dispersion and a negative chromatic dispersion slope. The fiber can be used in compensation dispersion modules or as line fiber, in transmission systems using line fiber with negative chromatic dispersion.

Abstract: The fibre is adapted to compensation of the chromatic dispersion and chromatic dispersion slope of an optical fibre with negative chromatic dispersion. It has, in a propagation mode other than the fundamental mode, a positive chromatic dispersion and a negative chromatic dispersion slope.

Abstract: The invention relates to non-soliton RZ signal fiber optic transmission systems. To reduce the effects of non-linear interaction between adjacent pulses, it proposes that the phase difference between the end of one pulse and the beginning of the adjacent pulse be in the range from 2&pgr;/3 to 4&pgr;/3.

Abstract: An optical transmission system for transmitting an optical signal through an optical fiber transmission line includes a first optical fiber transmitting the optical signal and having a first zero-dispersion wavelength shorter than a wavelength of the optical signal, and a second optical fiber transmitting the optical signal from the first optical fiber and having a second zero-dispersion wavelength longer than the wavelength of the optical signal. A first nonlinear effective cross-sectional area of the first optical fiber is larger than a second nonlinear effective cross-sectional area of the second optical fiber.

Abstract: To optimize the efficiency of optical amplifiers operating in the L-band, an L-band optical amplifier includes a doped fiber having a cut-off wavelength greater than 1 535 nm and a coupler for coupling into the fiber a pump supplying light in the C-band. The C-band pump is a high-power pump, with a power rating of at least 10 mW, which supplies at least 10% of the pumping energy. A pump operating at a wavelength below the C-band can also be coupled into the fiber, for example a 980 nm or 1 480 nm pump.

Abstract: WDM transmission system comprising transmitters 2 for generating optical signals in different channels, a multiplexer 3 for combining said optical signals into a WDM signals, a transmission line 4 for transmitting said WDM signal, a demultiplexer 6 for demultiplexing the WDM signal received from the transmission line 4 and receivers 7 for receiving the optical signals of each channel, characterized in that it further comprises a Raman depletion compensator 8, 10 for compensating the depletion due to Raman-shift in the power of the wavelength grid spectrum.

Abstract: The invention relates to a system and method for determining wavelength dependent information in optical signal transmission systems. According to the invention after a plurality of optical signals at different wavelengths are launched into the transmission system, backscattered and/or reflected signal portions are received for each wavelength, and subsequently processed to determine wavelength dependent information about the transmission system. With the present invention the gain evolution along the transmission link can be measured, after the transmission system is installed. In particular this is advantegous for submarine optical signal transmission systems.

Abstract: The present invention provides a method of dispersion compensation comprising the steps of:

Abstract: A method of manufacturing a multi-core optical fiber, the method including assembling together a plurality of substantially identical single-core optical fiber preforms (2', 2"), referred to as "single-core preforms", each of which includes a core bar (3) surrounded by a layer of optical cladding (4), so as to form a "multi-core preform" (10) and drawing down the multi-core preform (10) so as to obtain the multi-core optical fiber. The assembly step includes securing the single-core preforms (2', 2") to one another by fusing them over their entire lengths or over portions thereof along their tangential lines of contact (T), without inserting the multi-core preform (10) into a holding tube. A vacuum is maintained in the preform during the drawing step, the vacuum being formed before or during the drawing step.

Abstract: To increase the transmission length in an optical fiber, a method of transmitting digital data uses both power modulation and phase modulation of an optical carrier. To compensate the chromatic dispersion produced by the fiber, a phase-shift is applied to the wave within each time cell in which the optical power is low and that precedes or follows a cell in which the power is high. Applications include long-distance optical transmission using standard fibers.

Abstract: Optical pulses carrying information to be conveyed are routed, for each pulse, by the intensity of the pulse. The pulses may be solitons. The invention is particularly applicable to long distance communications.

Abstract: The object of the invention enables wavelength division multiplexed solitons conveyed by an optical fiber to be regenerated synchronously. The method uses clock recovery from the WDM signal, and synchronous modulation of the solitons at the clock rate recovered in this way. The locations for the optical modulators are selected to be at a distance between the transmitter and the first modulator or between successive modulators along the optical link such that the signals at different wavelengths are synchronous. The apparatus of the invention regenerates solitons in-line by synchronously modulating said solitons using an optical modulator, clock recovery, and multichannel filtering at the output from the modulator. In a particular embodiment, the telecommunications system of the invention also includes fiber lengths having different dispersion relationships depending on their position within the link, so as to achieve "dispersion management" within the link.

Abstract: A method of manufacturing a multi-core optical fiber, the method including assembling together a plurality of substantially identical polished single-core optical fiber preforms (2', 2"), referred to as "single-core preforms", each of which includes a core bar (3) surrounded by a layer of optical cladding (4), so as to form a "multi-core preform" (10), and drawing down the multi-core preform (10) so as to obtain the multi-core optical fiber. The assembly step includes securing the single-core preforms (2', 2") to one another by fusing them over their entire lengths or over portions thereof along their tangential lines of contact (T), without inserting the multi-core preform (10) into a holding tube. A vacuum is maintained in the preform during the drawing step, the vacuum being formed before or during the drawing step.

Abstract: A system for writing a Bragg grating point-by-point in an optical waveguide includes an illumination system for producing a primary beam. It further includes a diffraction grating to receive the primary beam and to produce a zero order secondary beam and two symmetrical secondary beams of higher order and a focusing optical device for focusing the secondary beams onto a writing area of the waveguide. The diffraction grating and the focusing optical device define an intensity function of writing in the area of the guide including a central peak and two secondary peaks spaced from the central peak by a distance equal to the pitch of the grating.

Abstract: A laser source supplies a primary laser beam. A phase grating generates two secondary beams from the primary beam so as to form interference fringes that are inscribed in an optical fiber by photo-refraction. An optical system of variable focal length varies the gap between the interference fringes so as to vary the pitch of the Bragg grating discretely for successive segments of the optical fiber. Means displace the primary laser beam and the optical fiber relative to each other by successive segments of said fiber. These means are synchronized with the variation of the focal length of the optical system. Application to telecommunications.

Abstract: An amplifying fiber is connected at both ends to two respective pump-forming semiconductor lasers. The connections are made via two pump injection fibers and two multiplexers. According to the invention, each of the two pump injection fibers includes a respective photorefractive filter constituting a portion of the resonant cavity of the associated pump, and serving to separate the spectrum bands of the pumps. The invention is particularly applicable to optical fiber telecommunications networks.

Abstract: A link using spectrum multiplexing, in which link an amplifying fiber amplifies a plurality of multiplexed carrier waves. The invention makes it possible to maintain a flat spectrum distribution of the gain of the amplifying fiber when the number of carrier waves varies. For that purpose, light that is amplified by the amplifying fiber and that is independent of the carrier waves is servo-controlled in power. The light is constituted by a reverse amplified spontaneous emission. After being filtered in a filter and detected by a photodiode, the light controls the power supplied to two laser diodes for pumping the fiber. The invention applies in particular to implementing optical transmission networks.