Alcatel

Alcatel Submarine Networks

Alcatel N.v.

Alcatel Alsthom Compagnie Generale D'electricite

Emmanuel Desurvire

Olivier Leclerc

Jose Chesnoy

Patrick Brindel

Sebastien Bigo

Pascale Nouchi

Denis Penninckx

Christian Le Sergent

Jean-Pierre Hamaide

Catherine Martinelli

Bruno Dany

Elisabeth Maunand

Frédéric Seguineau

A multichannel wavelength-division multiplex fiber optic transmission system includes an optical transmitter and an optical receiver connected by an optical line including at least one optical fiber and at least one set of channel regenerators. Successive regenerators regenerate respective groups of channels forming a subset of the set of channels.

WDM regenerated transmission system

A method for remodulation of a modulated optical signal is disclosed which uses a disturbed line signal and an optical clock signal derived from the undisturbed original line signal modulated with the bitrate frequency feeding both signals in a Raman amplifying fiber connected to at least one Raman pump running the clock signal as Raman pump wavelength for the line signal.

Method for remodulation of a modulated optical signal and device for remodulation and transmission system

A synchronous optical regenerator applies intensity modulation and phase modulation. The phase modulation is effected after the intensity modulation by the crossed Kerr effect in a Kerr fiber. The clock used for the phase modulation is obtained by injecting a continuous wavelength into the intensity modulator. The regenerator therefore includes a multiplexer coupling continuous light with the signals transmitted, an intensity modulator modulating the signals transmitted and the continuous light, and a Kerr fiber phase modulating the transmitted signals by crossed phase modulation with the intensity-modulated continuous light. Applications include wavelength division multiplex transmission systems.

Synchronous optical regenerator using intensity modulation and phase modulation by the crossed kerr effect

The invention relates to wavelength division multiplex fiber optic transmission systems. It proposes a regenerator including a demultiplexer for separating the signals of various channels, a plurality of optical modulators each receiving signals from the demultiplexer and a modulation clock from a clock distribution unit, and a multiplexer combining the signals modulated by the modulators. The clock distribution unit includes a reference clock and, for each modulator, means for synchronizing the phase of a copy of the reference clock with the signals applied to the modulator. A phase-locked loop can be used for phase synchronization, with a phase shifter controlled in accordance with the average power of the signals at the output of the modulator. The invention enables only low-frequency components to be used to generate modulation clocks from a single reference clock.

Regenerator for a wavelength division multiplex transmission system

To delay optical signals precisely and continuously in a very small dynamic range, a device for applying a time-delay to optical signals includes a first phase modulator to receive an input optical signal carried by an original center wavelength and to apply a first stage of phase modulation to the carrier wave of the input signal to supply a first intermediate signal carried by a modified center wavelength, a delaying dispersive member having chromatic dispersion to receive the first intermediate signal and to supply a second intermediate signal, and a second phase modulator to receive the second intermediate signal and to apply a second stage of phase modulation to the carrier wave of the second intermediate signal to supply an output signal carried by the original center wavelength. Applications include optical telecommunication systems, in particular converting wavelength division multiplexed signals into time division multiplexed signals and regenerating wavelength division multiplexed signals.

Device for applying time-delays to optical signals

Double filtering fiber optic soliton signal transmission system

A method of detecting one or more free channels in a time-division multiplexed optical signal which may be used for insertion signals in switching nodes of optical communication networks. The method includes sampling successive optical pulses from at least one of said channels, measuring the average optical power of the sampled pulses during a predetermined time period, and generating a detection signal if said average optical power is less than or equal to a predetermined threshold value.

Method of detecting one or more free channels in an optical time-division multiplex, a device for implementing it and the use of the device

The invention enables wavelength division multiplexed (WDM) solitons conveyed by an optical fiber to be regenerated synchronously. The invention consists in using optical delay lines, in particular of the photorefractive filter type, prior to the regenerators so as to resynchronize a subset of the m soliton channels, and in placing the regenerator at a position where the n-m other soliton channels are naturally synchronized.

Method and device for on-line regeneration of a signal transmitted by wavelength division multiplexed solitons and optical telecommunication system comprising such a regenerating device

An optical fiber transmission system for soliton signals with wavelength multiplexing in which the bit times of the various channels &lgr;,to &lgr;,of the multiplex are substantially synchronous, at least at one point. At least one saturable absorber is located at this point. The channels can be made synchronous by an appropriate selection of wavelengths, or by using optical delay lines, or the like. The saturable absorber then modulates the intensity of the soliton signals in the various channels of the multiplex. It is possible to use a clock for remotely driving the saturable absorber. The invention also relates to a corresponding transmission method. The invention makes it possible to transmit over long distances without using active components.

Optical fiber transmission system for soliton signals with wavelength multiplexing and saturable absorbers

The invention concerns a wavelength-division multiplex soliton signal fiber optic transmission system; to reduce the effects of collision jitter on the soliton channels, it proposes quasi-distributed amplification combining lumped amplification and distributed amplification. In this way it is possible to combine pumping of a lightly doped line fiber an dumped amplification by an EDFA in the repeaters. Reduncant and common pumping means are advantageously used for the lumped amplification and the distributed amplification and the gain of the lumped amplification is advantageously controlled automatically.

Quasi-distributed amplification in a fiber optic soliton signal transmission system

A method of regenerating non-soliton RZ optical signals, the method including the steps of: a compression step, whereby the RZ signals are compressed into soliton-type signals; a modulation step whereby synchronous optical modulation is performed on the soliton-type signals, by using a clock; and a decompression step whereby the modulated soliton signals are decompressed into non-soliton RZ signals. The method makes it possible to apply soliton modulation techniques to non-soliton RZ links, so as to increase the data rate or the transmission length of such inks without inducing errors, and without having to modify the transmission medium. The invention also relates to a regenerator operating using the method. It is also possible to apply the method to NRZ signals, by converting them into RZ signals. The invention is also applicable to multiplexed RZ or NRZ signals.

Optical regeneration for optical-fiber transmission systems for non-soliton signals

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

Optical fiber including a fluorescent dopant

The invention relates to an adjustable optical amplitude and phase modulator using a non-linear optical loop mirror having two control inlets and a signal inlet. In a preferred embodiment, a single clock signal is split into two and applied to the two control inlets. The invention also relates to a soliton regenerator including said optical modulator. In an important variant, said modulator receives a soliton bit train on its signal inlet at a bit rate f.sub.s, and on its control inlets it receives a clock signal at half that frequency f.sub.c =f.sub.s /2. In an advantageous embodiment, said clock signal is applied with a phase shift of .pi. between the two control inlets, so as to minimize the effects of collisions between solitons. The invention is applicable to long distance telecommunications by optical fiber.

Adjustable optical amplitude and phase modulator, and a soliton

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.

Growing community of inventors

Bruyeres le Chatel, France

Emmanuel Desurvire