Pirelli Cavi E Sistemi S.p.a.

Cisco Photonics Italy S.r.l.

Paolo Ottolenghi

Filippo Bentivoglio Ravasio

Giorgio Grasso

Aldo Righetti

Mauro Macchi

Steffen Schmid

Gainluca Bonato

Fabio Donati

Massimo Frascolla

An optical transmission system and method for reducing non-linear distortion caused by the interaction of Self-Phase Modulation and Group Velocity Dispersion is disclosed. An optical link includes a transmitter for providing signals at a first optical wavelength, a transponder for converting the first optical wavelength to a second optical wavelength, a plurality of spans of optical transmission fiber and optical fiber amplifiers, a dispersion compensating device, and a receiver. The system operates at a relatively high input power level. The transponder includes a device for smoothing edges of the rise and fall times of optical pulses, such as an electrical attenuator and low pass filter, so that sharp-edged pulses received from the transmitter are transformed to a Gaussian shape. A dispersion compensating device, such as an optical fiber grating, also helps to improve the bit error rate as a function of receiver sensitivity despite an overall link length less than 600 km.

Apparatus and method for reducing SPM/GVD in optical systems

An apparatus and method for reducing polarization hole burning in a rare-earth-doped fiber amplifier within an optical communication system by converting an optical carrier having a characteristic wavelength into a polarization-rotating optical carrier is disclosed. The apparatus includes a polarization-fixing device optically coupled in the optical transmission system to transform the optical carrier to a polarized optical carrier, and an acousto-optic modulator positioned to receive a first portion of the polarized optical carrier and to orthogonally convert the polarization of the polarized optical carrier and to shift the polarized optical carrier by a modulation frequency. The apparatus and method further includes a polarization beam combiner optically coupled to receive the orthogonally polarization converted and frequency shifted polarized signal and a portion of the original polarized optical carrier. The polarization beam combiner produces a polarization-rotating carrier signal that is transmitted downstream in the optical communication system to a rare-earth-doped fiber amplifier.

Suppression of polarization hole burning with an acousto-optic modulator

An improvement in the reliability of an optical communication system comprising two optical fiber lines, a first transmitter for transmitting at least a signal in the first optical line, a second transmitter for transmitting at least a signal in the second optical line, at least one two-stage-amplifier in each of said first and second line, laser pumps providing pumping signals to said stages of the amplifiers, a first receiver for receiving the signal from the first optical line, and a second receiver for receiving the signal from the second optical line, wherein said laser pumps form a single system that provides a first pumping signal to at least one stage of said at least one amplifier of each of said first and second line.

Reliability of an optical communication system and of an optical amplifying system, and a method suitable to this aim

Optical telecommunications system

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Sceaux, France

Paolo Ottolenghi