Google Inc.

Pirelli Cavi E Sistemi S.p.a.

Mosaid Technologies Corporation

Pgt Photonics, S.p.a

Corning O.t.i. Inc.

Lucia Marazzi

Pierpaolo Boffi

Mario Martinelli

Paola Parolari

Aldo Righetti

Paolo Martelli

Livio Paradiso

Rocco Siano

Giorgio Grasso

Marco Romagnoli

Giovanni Tamiri

A method of phase modulating optical radiation by the steps of phase modulating the optical radiation by using a modulator having an extinction ratio in order to provide a multilevel phase shift key signal, and applying to each optical pulse a phase-shift having an absolute value depending on the extinction ratio and a sign depending, for each of the optical pulses, on the respective optical phase value. An apparatus implementing the method is also disclosed.

Method and apparatus for optical phase modulation

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 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 wavelength converter or demultiplexer device comprising first and second stages (). For wavelength converter action, the first stage impresses an intensity modulation (IM) and phase modulation (PM) on a CW input signal (&#x3bb;) carried by an input DATA signal (&#x3bb;) using cross phase modulation in a non-linear optical element (). The first stage in an embodiment is a semiconductor laser amplifier loop optical mirror (SLALOM) which has a semiconductor optical amplifier (SOA) as the non-linear optical element. The second stage has a non-linear transfer function and impresses a further IM on the optical signal responsive to the PM impressed in the first stage. In an embodiment, the second stage is a polarization maintaining fiber (PMF) optical loop. The transfer function of the overall device is thus improved by making it steeper and more time confined. This is achieved by combining a fast first stage with a second stage that has a non-linear transfer function, so that the residual PM from the first stage synchronously drives a nonlinear process in the second stage.

Intensity modulation of optical signals

An optical device for providing threshold and comparison functions. The device comprises first and second SOA's having respective first and second propagation paths along which the first and second optical signals, input as signals P (&lgr; ) and P (&lgr; ) travel in first and second forward directions. A feedback path is provided using couplers to interconnect the outputs of the SOA's. As a result, a portion of the optical signals output from each SOA is supplied backwards into the output of the other SOA as feedback optical control signals P (&lgr; ) and P (&lgr; ). The feedback optical control signals modulate the gain of the forwards travelling optical signals by cross gain modulation (XGM). In contrast to prior art devices, the optical control signal is supplied backwards into the SOA's in a counter-propagating configuration. This allows much shorter feedback path lengths to be achieved in comparison to what is possible with prior art co-propagating configurations. Consequently, much higher bit rates can be achieved. The device may also be implemented in planar waveguide technology.

Optical threshold and comparison devices and methods

An optical window signal generator which begins generation of an optical output signal in response to an optical activation pulse, and terminates generation of the optical output signal in response to an optical deactivation pulse. The rise time of the optical output signal is equal to the rise time of the optical activation pulse, and its fall time is equal to the rise time of the optical deactivation pulse.

Optical window signal generator

There is provided an optical wavelength converter which allows the rapid and efficient shifting of information modulated on a light signal of one wavelength to a light signal of a second wavelength without the negative effects of noise and other disturbances which have proven to be problems in the prior art. The device splits a CW probe signal of a first wavelength into two components, which propagate with opposite orientations through a Kerr leg. Also propagating in the Kerr leg is a modulated drive signal at a second wavelength. These signals interact in the Kerr leg, and are recombined at an output coupler so as to create interference between the two probe components. An intensity modulated probe signal is output.

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Pavia, Italy

Lucia Marazzi