Alcatel N.v.

Alcatel Cit

Alcatel Alsthom Compagnie Generale D'electricite

Alcatel Fibres Optiques

Other

Centre National De La Recherche Scientifique

Alcatel Lucent

Alcatel Submarine Networks

Jose Chesnoy

Pierre Sansonetti

Isabelle Riant

Dominique Bayart

Andre Tardy

Emmanuel Desurvire

Claude Brehm

Jean-Yves Boniort

Jean-Pierre Hamaide

Bertrand Clesca

Denis Penninckx

Jean-Michel Gabriagues

Olivier Audouin

Olivier Leclerc

Denis Leclerc

Jean-Pierre Blondel

Jean-Francois Marcerou

Alain Cordier

Jean-Luc Beylat

Jean-Jacques Bernard

Dominique Lesterlin

Laurence Prigent

Elisabeth Brun

Pierre Aussant

Marie-Paule Jurek

Lorenzo Fini

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.

Underwater connection assembly for use in underwater communication systems

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.

Method of manufacturing a multi-core optical fiber

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.

Optical method of transmitting digital data

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.

Method and a system for optical communications with passive routing

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. The invention is applicable to optical telecommunications over great distances by means of solitons.

Synchronous modulation method and apparatus for in-line regeneration of

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.

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.

Method of and system for writing a bragg grating point by point by point

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.

Method of forming a dispersing grating in an optical fiber

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.

Optical fiber amplifier with two directional pumping

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.

Transmission method and an optical link using multiplexing with

Method of applying time offset chromatic dispersion, dispersive optical

An amplifying optical fiber amplifies a plurality of wavelength-multiplexed carrier waves. The invention enables the gain as seen by each of the carrier waves to be maintained, in particular when the total input power varies. For that purpose, amplified spontaneous 'reverse' emission light is servo-controlled in power. After being filtered in a filter and detected by a photodiode, said light controls the powering current supplied to two laser diodes for pumping the fiber. The invention applies in particular to implementing optical transmission networks.

Regulated optical amplifier

An electrical power supply (20, 22) powers a semiconductor laser chip (2) under gain switching conditions so as to make the chip emit light pulses. The light pulses are compressed in a fiber (30) having negative dispersion, so that they constitute solitons. Their spectrum width is decreased by the fact that a gain segment powered by the power supply constitutes only a portion of the length of the resonant cavity of the chip. The invention applies to transmitting data over optical fibers.

Gain-switched semiconductor light pulse source, and a soliton

Transmission line sections in a connection comprise passive portions transmitting the signal without compensating for its natural attenuation and occupying 15% to 65% of the length of the section. They also include active portions that amplify the signal. The invention is particularly applicable to making intercontinental connections.

Connection with amplifying optical fibers

An optical communication link with correction of non-linear effects comprises an optical fiber transmission line subject to chromatic dispersion and non-linear effects and correction means for limiting the disadvantageous consequences of this dispersion and/or these non-linear effects. The correction means comprise at the output of the transmission line a dispersion compensator adapted to apply dispersion in the opposite direction to and of lower absolute value than the dispersion due to the transmission line.

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Paris, France

Jose Chesnoy