Pirelli Cavi S.p.a.

Google Inc.

Societa Cavi Pirelli S.p.a.

Padtec S.a.

Pgt Photonics, S.p.a

Politecnico Di Milano

Pirelli Cavi E Sistemi S.p.a.

Fondazione Centro Internazionale Della Fotonica Per Energia

Aldo Righetti

Giorgio Grasso

Flavio Fontana

Paolo Martelli

Mario Martinelli

Pierpaolo Boffi

Lucia Marazzi

Fausto Meli

Mario Tamburello

Silvia Maria Pietralunga

Paola Parolari

Maria Chiara Ubaldi

Rocco Siano

Marco Romagnoli

Andrea Ivano Melloni

Francesco Morichetti

Paolo Ottolenghi

Fabio Donati

Giovanni Tamiri

Daniele Androni

Andrea Melloni

The present invention relates to a method to tune a wavelength of a coherent light signal emitted by a tunable laser, the tunable laser comprising:

Tunable laser and method to tune a wavelength of a light emitted by the laser

An optical amplifier (), and a related optical amplification method, comprising an optical path () having an input end () and an output end (), a first erbium doped optical fiber () placed along the optical path, a first gain flatting filter () placed along the optical path downstream the first erbium doped optical fiber, a second erbium doped optical fiber () placed along the optical path downstream the first gain flatting filter, a second gain flatting filter () placed along the optical path downstream the second erbium doped optical fiber, a third erbium doped optical fiber () placed along the optical path downstream the second gain flatting filter, and an optical pump () optically coupled to the optical path so as to optically pump at least the first and the third erbium doped optical fiber.

Optical amplifier and related method

A branching unit () for an optical telecommunication link (), the unit comprising a first (), a second () and a third terminal () for termination of conductors of respective branch cables in use, a fourth terminal () for connection to a sea earth () in use, and a circuit () comprising a plurality of relays comprising at least a first, a second and a third relay associated to respectively the first, second and third terminal, the circuit being structured for connecting together two terminals out of the first, second and third terminal and for connecting the remaining terminal to the fourth terminal, depending on a sequence of power feeding at the first, second and third terminals, in use, wherein the circuit () comprises a sea earth circuit () terminated at one end to the fourth terminal and a bidirectional triode thyristor () placed along the sea earth circuit, a driving circuit () being provided for driving the bidirectional triode thyristor so as to trigger the bidirectional triode thyristor in a conduction state only upon complete switch-over of one relay of the group consisting in the first, second and third relay.

Branching unit for an optical telecommunication link

Optical amplification stage () for OTDR monitoring, comprising a first () and a second optical signal path (), a first () and a second optical amplifier (), a first optical coupler () placed along the first optical signal path downstream the first optical amplifier, a second optical coupler () placed along the second optical signal path downstream the second optical amplifier, an optical by-pass path () optically connecting the first and the second optical coupler, a first () and a second optical reflector () optically connected to respectively the first and second optical coupler, and an optical filter () placed along the optical by-pass path which has attenuation high on the whole WDM band and low at the OTDR wavelength(s).

Optical amplification stage for OTDR monitoring and related method and system for OTDR monitoring of an optical communication link

A solar concentrator () having a longitudinal axis of extension () and a cross-section at right angles to the longitudinal axis substantially equal for a continuum of cross-sections, and comprising a reflective system () and a refractive system (), the reflective system forming an optical inlet () and an optical outlet () and comprising two semi-portions positioned specularly relative to the plane of symmetry, where the cross-section profile of the refractive system is a triangle () having a base () at the optical outlet () and apex () on the axis of symmetry (), where the cross-section profile of each semi-portion of the reflective system comprises a segment () in the shape of a parabola having an axis () forming with the axis of symmetry an acceptance angle (&#x3b8;0) greater than zero and a focus (F) on the axis of symmetry, and where the focus falls inside the triangle.

Solar concentrator for photovoltaic systems

An optical communication system () comprises at least a transmitter () apt to emit a differential phase shift keying (DPSK) optical signal having a bit-rate equal to R, at least a receiving system () for receiving the differential phase shift keying optical signal; and an optical link () optically connecting the transmitter and the receiving system for transmitting the DPSK optical signal from the transmitter to the receiving system, wherein the receiving system comprises a coherent optical receiving device () apt to coherently receive the propagated DPSK optical signal and to emit at least one electrical signal (I) related to the received DPSK optical signal, and wherein the receiving system further comprises at least one electrical filter () for filtering the at least one electrical signal and having &#x2212;3 dB double-side bandwidth greater than or equal to 0.44 R and lower than or equal to 0.68 R, and at least one squarer () for squaring the at least one filtered electrical signal. A related method for optical communication is also disclosed.

System and method for coherent detection of optical signals

An optical transmission system having an optical source, an optical dispersion compensation filter optically connected to the optical source, and a control system. The optical source generates a modulated optical signal having an optical spectrum and a value of dispersion robustness. The optical dispersion compensation filter has at least two cascaded optical resonators and a periodic transfer function rigidly translatable in the frequency spectrum to obtain translation in frequency of the transfer function without a substantial change in shape, and characterized by a free spectral range. The control system acts on the optical dispersion compensation filter in order to rigidly translate the transfer function along the frequency spectrum in first and second positions in the frequency spectrum. The translation of the transfer function between the first and the second positions is smaller than the free spectral range.

Optical transmission system with optical chromatic dispersion compensator

A method of stabilizing the state of polarization of an optical radiation comprises: 1) applying sequentially to the optical radiation a first and a second controllable phase retardation; 2) detecting an optical power of at least a first polarized portion of the optical radiation obtained after step 1; 3) applying sequentially to the optical radiation obtained after step 1 a third and a fourth controllable phase retardation; 4) detecting an optical power of a further polarized portion of the optical radiation obtained after step 3; 5) controlling, responsive to the optical power of said first polarized portion, the second controllable phase retardation so as to maintain the polarization state of the optical radiation obtained after step 1 at a defined great circle r on a Poincare sphere; 6) in case the second controllable phase retardation reaches a first limit value, commuting the first controllable phase retardation between first and second values; 7) controlling, responsive to the optical power of said further polarized portion, the fourth controllable phase retardation so as to maintain the polarization state of the optical radiation obtained after step 3 at a defined state of polarization; 8) in case the fourth controllable phase retardation reaches a second limit value, commuting the third controllable phase retardation between third and fourth values, keeping constant the first controllable phase retardation while the third controllable phase retardation is commuting between said third and fourth values. A polarization stabilizing device based on the method above is also disclosed.

Method and device for polarization of an optical radiation

A device and method for stabilizing the state of polarization of polarization multiplexed optical radiation including an identified channel is disclosed. The device and method comprise providing to the polarization multiplexed optical radiation a first controllable polarization transformation to generate a first transformed optical radiation; detecting a first state of polarization of a first polarized portion with respect to a first polarization parameter; controlling the first controllable polarization transformation so that the first polarization parameter has a predetermined value independent of a polarization state of the polarization multiplexed optical radiation; providing to the first transformed optical radiation a second controllable polarization transformation to generate a second transformed optical radiation; detecting a second state of polarization of a second polarized portion; and controlling the second controllable polarization transformation so that the second state of polarization has a predefined value.

Method and device for stabilizing the state of polarization of a polarization multiplexed optical radiation

A device and method for stabilizing the polarization of polarization multiplexed optical radiation includes an identified channel which is provided with a pilot signal. The device and method are based on providing to the polarization multiplexed optical radiation a controllable polarization transformation; measuring the optical power of a polarized portion of the identified channel downstream the polarization transformation; controlling, responsively to the optical power, the controllable polarization transformation so that the identified channel downstream the polarization transformation has a predefined polarization azimuth; providing to the optical radiation downstream the polarization transformation a further controllable polarization transformation; measuring the optical power of a polarized portion of the identified channel downstream the further controllable polarization transformation; and controlling, responsively to the optical power, the further controllable polarization transformation so that the identified channel downstream the further controllable polarization transformation has a predefined state of polarization.

A polarization stabilizing device and method based on controlling the phase retardations of a pair of variable rotators with an optically interposed quarter-wave plate, with a controller such that the first of the variable rotators has its phase retardation switched between first and second values whenever the phase retardation of the second of the variable rotators reaches an upper or a lower limit. The upper and lower limits of the second rotator and the first and second values of the first rotator are chosen so that discontinuities in the power of the output optical radiation are avoided when the first variable rotator is switched, thereby providing endless polarization stabilization using rotators that themselves may have limited retardation ranges.

Method and device for stabilizing the state of polarization of optical radiation

Optical telecommunications system

An optical fiber power amplifier, particularly for telecommunication lines with optical fibers, including an active fiber doped with Erbium as a fluorescing substance, and with Al.sub.2 O.sub.3 as refraction index modifying dopant. The fiber is pumped with a laser providing a wavelength higher than 520 nm and preferably, 980 nm. The amplifier has a particularly high amplification efficiency close to the theoretical maximum efficiency.

Optical power amplifier with Al.sub.2 O.sub.3 and erbium doped active

An optical signal generator for telecommunication systems, comprising at least a single-frequency active optical fiber laser as an optical signal source at a signal transmission wavelength, at least an active optical fiber optical amplifier operatively connected to said laser and at least one source of pumping optical power at a pumping wavelength, the pumping optical power source being operatively connected to at least one of said active fibers of said laser and amplifier and transfer-means for said pumping optical power being connected to said active fibers of said laser and amplifier, in order to transfer unabsorbed optical power at the pumping wavelength from one of said active fibers to the other of said active fibers.

High-power signals optical generator for telecommunication systems

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.

Growing community of inventors

Milan, Italy

Aldo Righetti