Pirelli Cavi S.p.a.

Cisco Technology, Inc.

Cisco Photonics Italy S.r.l.

Pirelli Cavi E Sistemi S.p.a.

Corning O.t.i. Inc.

Mario Tamburello

Giorgio Grasso

Stefano Vanoli

Marcos Antonio Brand&atilde;o Sanches

Fausto Meli

Aldo Righetti

Fulvio Arecco

Adriano Nava

Stefano Simone Turzi

Piergiovanni Matrona

Francesca Loseto

Marcos Antonio Brandão Sanches

The spectrum of a received WDM band or subband is analyzed to detect failure of, e.g., fiber or amplifiers along a line. In one implementation, measurements are taken within the optical spectrum at locations of expected data-carrying optical signals and at two locations just outside the wavelength range occupied by these signals. Magnitudes of adjacent measurements are compared to obtain differences. If none of the differences exceed a threshold, a fault may be determined.

Subband spectrum analysis for optical multiplex section protection

Communicating a signal includes receiving the signal at a primary device of a switching system, where the primary device is associated with a primary path along which the signal is propagating. A primary overmodulation signal associated with the primary path is generated. The absence of the primary overmodulation signal is detected, and an operating signal is sent from the primary device to a secondary device of the switching system, where the secondary device is associated with a secondary path. The operating signal operates to initiate propagation of the signal along the secondary path.

Optical communication system

An optical communication system for communicating at least a first optical system. The optical communication system includes a first primary guided optical path and a first secondary guided optical path, through each of which the first optical signal is configured to propagate. A first primary optical amplifier is provided in the first primary guided optical path and is configured to transmit an overmodulation frequency of the first optical signal. A first secondary optical amplifier is provided in the first secondary guided optical path and is configured to transmit the overmodulation frequency of the first optical signal. A controller controls propagation of the first optical signal from the first primary guided optical path to the first secondary guided optical path based on the detected presence of the overmodulation frequency.

Device for adding/dropping optical signals into/from an optical transmission path, including input means for at least two optical signals with distinct wavelengths, comprising spectral selection means for sending at least a first signal to a first optical path and at least a second signal to a second optical path, at least a wavelength selective switching means along at least one of said first and second optical paths, for adding and dropping at least one optical signal having a predetermined wavelength selected from the optical signal wavelengths.

Device for adding and dropping optical signals

A multi-channel optical telecommunication system and method for transmitting optical signals having distinct wavelengths. Spectral selection is provided for the optical signals to add or drop signals of predetermined wavelengths. The signals are divided into at least two series of different wavelengths. The signals of each series are dropped or signals of corresponding wavelengths are added, and the signals are then combined.

A digital optical telecommunication method including the steps of: generating a digital modulated optical signal in an optical transmitting station, which signal corresponds to a first electric input signal carrying a piece of information; feeding the modulated optical signal to an optical-fibre line; receiving the modulated optical signal transmitted from the optical-fibre line at an optical receiving station, converting it to an electric form and thereat generating a second digital electric signal; wherein the modulated optical signal is coded in a sequence of elementary information units at a first frequency and wherein the step of generating a second digital electric signal comprises detecting in said converted signal, an electric signal having a second frequency higher than the first frequency and recognizing in said detected signal, the phase of an electric signal at the first frequency by comparing a received sequence of elementary information units with at least one reference sequence and verifying their correspondence to a predetermined condition.

Optical telecommunication method providing a transmitting and receiving service channel

A digital optical telecommunication method including the steps of: generating a digital modulated optical signal in an optical transmitting station, which signal corresponds to a first electric input signal carrying a piece of information; feeding the modulated optical signal to an optical-fiber line; receiving the modulated optical signal transmitted from the optical-fiber line at an optical receiving station, converting it to an electric form and thereat generating a second digital electric signal; wherein the modulated optical signal is coded in a sequence of elementary information units at a first frequency and wherein the step of generating a second digital electric signal comprises detecting in said converted signal, an electric signal having a second frequency higher than the first frequency and recognizing in said detected signal, the phase of an electric signal at the first frequency by comparing a received sequence of elementary information units with at least one reference sequence and verifying their correspondence to a predetermined condition.

Optical telecommunication method providing a transmitting and receiving

A multi-wavelength optical telecommunication method includes the steps of generating at least one optical transmission signal in a predetermined wavelength band, transmitting the optical transmission signal through an optical fibre to a receiving station, receiving the optical transmission signal through a passband filter and filtering the signal to let the transmission signal alone pass. The wavelength band is scanned in order to identify in the band a recognizable portion of the optical spectrum being received, thus determining, based on the operating conditions corresponding to the recognizable spectrum portion, a search range of the transmission signal within which the transmission signal is searched out and recognized based on its spectral profile.

Telecommunication system and method for wavelength-division multiplexing

A multi-wavelength optical telecommunication method includes the steps of generating at least one optical transmission signal in a predetermined wavelength band, transmitting the optical transmission signal through an optical fiber to a receiving station, receiving the optical transmission signal through a passband filter and filtering the signal to let the transmission signal alone pass. The wavelength band is scanned in order to identify in the band a recognizable portion of the optical spectrum being received, thus determining, based on the operating conditions corresponding to said recognizable spectrum portion, a search range of said transmission signal within which the transmission signal is searched out and recognized based on its spectral profile.

The telecommunication line comprises at least one terminal station having an optical-signal transmitter and an optical-signal receiver, which are operationally connected by an automatic protection device suitable for shutting down said transmitter in the absence of a received optical signal, at least one opticalfibre line for the transmission of the optical signals transmitted by said transmitter and received by said receiver, and at least one optical amplifier included in said line. With said optical amplifier there are associated means for the detection of the presence of light energy at input and means for causing the shut down of the amplifier, which in the absence of light energy at input are caused by said detection means to interrupt substantially any emission of light energy on the part of said optical amplifier.

Fiber optical communication line with shut off control

An optical fiber telecommunications system having two terminals interconnected by optical fibers and active-fiber optical amplifiers. Each terminal has an optical telecommunication signal transmitter associated with an optical signal receiver which are interconnected by a protective device which causes the transmitter to be inoperative when its associated receiver does not receive an optical signal. Optical switches are provided at the downstream sides of active-fiber optical amplifiers and are controlled by detecting devices coupled to amplifier outputs, each of which detecting devices opens the associated switch in the absence of a signal having the characteristics, e.g. an alternating component, of the optical telecommunication signal whereby the protective devices are operated.

Optical-fibre telecommunications line with protection device for optical

Adapters for interconnecting optical fiber lines, including optical amplifiers, with optical transmitters and receivers in which the operating parameters of the optical amplifiers are different from the operating parameters of the transmitters and receivers. The adapters convert the optical signals from a transmitter to those within the operating parameters of the optical amplifier and convert the optical signals from an optical amplifier to those within the operating parameters of the receiver. The adapter receiving the optical signals from the transmitter also has provision for inserting service signals and the adapter receiving signals from an optical amplifier has provision for separating the optical signals from the service signals. Also, switching devices for changing transmitters and/or receivers or lines in the event of component failures.

Amplifier adapter for optical lines

An optical fiber transmission line which includes units for injecting into, and units for extracting, optical service signals from the line's optical fiber. The units include optical service signal emitters and receivers for receiving from the optical line and/or injecting into the optical line service signals in the form of optical signals having a wavelength which is substantially different from the wavelength of the telecommunication signals also transmitted over the optical line, each of the units is associated with an optical coupler which is inserted in the line and which is suitable for coupling it with the line fiber and/or for extracting the optical service signals from the line fiber.

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Vimercate, Italy

Mario Tamburello