Self-coherent robust spectrally efficient optical transmission systems

Patent metadata

Field	Value
Publication number	US-2016065314-A1
Application number	US-201514842850-A
Country	US
Kind code	A1
Filing date	Sep 2, 2015
Priority date	Sep 2, 2014
Publication date	Mar 3, 2016
Grant date	—

Abstract

Coherent reconstruction of dual polarized data and pilot signals without local oscillator or laser.

First claim

We claim:

1 . An optical receiver that comprises an extraction circuit, a pilot generator, a first coherent detector and a second coherent detector;
wherein the extraction circuit is configured to (a) receive, from an optical communication link, a received signal that comprise first polarized data, second polarized data, a first polarized pilot component, and a second polarized pilot component and (b) extract the first and second polarized pilot components, the first polarized data and the second polarized data; wherein the first and second polarized pilot components belong to a pilot signal that has a pilot frequency that is within a frequency gap formed in a data spectrum that comprises frequencies of the first and second polarized data; wherein the first polarized data and the first polarized pilot components are of a first polarization and wherein the second polarized data and the second polarized pilot components are of a second polarization that differs from the first polarization; wherein the pilot generator is configured to coherently sum the first and second polarized pilot components and to generate first and second reconstructed pilot signals of substantially a same power; wherein the first coherent detector is configured to receive the first reconstructed pilot signal and the first polarized data and to output at least one first data stream; and wherein the second coherent detector is configured to receive the second reconstructed pilot signal and the second polarized data and to output at least one second data stream.

2 . The optical receiver according to claim 1 wherein the receiver does not include a local oscillator.

3 . The optical receiver according to claim 1 wherein the receiver does not include a laser.

4 . The optical receiver according to claim 1 wherein the pilot generator comprises a controller that is configured to detect a difference between powers of the first and second reconstructed pilot signals and to send a feedback signal that reduces the difference.

5 . The optical receiver according to claim 4 wherein the pilot generator comprises a pair of phase modulators followed by a coupler; wherein the feedback signal is configured to change a phase shift between the pair of phase modulators in response to the difference between powers of the first and second reconstructed pilot signals.

6 . The optical receiver according to claim 1 wherein the pilot generator is a partial Mach Zehnder Modulator that comprises a pair of phase modulators followed by a coupler.

7 . The optical receiver according to claim 6 wherein the pair of phase modulators are configured to operate in a push pull mode.

8 . The optical receiver according to claim 1 wherein the extraction circuit comprises a polarized de-multiplexer followed by a first filter bank and a second filter bank;
wherein the first filter of the first filter bank is configured to output the first polarized data and a second filter of the first bank filter is configured to output the first polarized pilot component; and
wherein the first filter of the second filter bank is configured to output the second polarized data and a second filter of the second bank filter is configured to output the second polarized pilot component.

9 . The optical receiver according to claim 1 wherein the first and second data streams are in phase and quadrature data streams.

10 . The optical receiver according to claim 1 wherein the first and second polarizations are orthogonal to each other.

11 . The optical receiver according to claim 1 wherein the frequency gap is positioned at a center of the data spectrum.

12 . The optical receiver according to claim 1 wherein the first and second coherent detectors are homodyne receiver detectors.

13 . The optical receiver according to claim 1 wherein the first and second coherent detectors are heterodyne receiver detectors.

14 . A optical transceiver that comprises an optical receiver and an optical transmitter;
wherein the optical receiver the comprises an extraction circuit, a pilot generator, a first coherent detector and a second coherent detector; wherein the extraction circuit is configured to (a) receive, from an optical communication link, received signals that comprise first polarized data, second polarized data, a first polarized pilot component, and a second polarized pilot component and (b) extract the first and second polarized pilot components, the first polarized data and the second polarized data; wherein the first and second polarized pilot components belong to a pilot signal that has a pilot frequency that is within a frequency gap formed in a data spectrum that comprises frequencies of the first and second polarized data; wherein the first polarized data and the first polarized pilot components are polarized by a first polarization and wherein the second polarized data and the second polarized pilot components are polarized by a second polarization that differs from the first polarization; wherein the pilot generator is configured to coherently sum the first and second polarized pilot components and to generate first and second reconstructed pilot signals of substantially a same power; wherein the first coherent detector is configured to receive a first portion of the first reconstructed pilot signal and the first polarized data and to output first and second data streams that form the first polarized data; wherein the second coherent detector is configured to receive a first portion of the second reconstructed pilot signal and the second polarized data and to output first and second data streams that form the second polarized data; wherein the optical transmitter is configured to receive four data streams, a second portion of the first reconstructed pilot signal and a second portion of the second reconstructed pilot signal and to output an output signal that represents the four data streams.

15 . A method for self-coherent reception, the method comprises;
receiving, by an extraction circuit and from an optical communication link, received signals that comprise first polarized data, second polarized data, a first polarized pilot component, and a second polarized pilot component; extracting, by the extraction circuit, the first and second polarized pilot components, the first polarized data and the second polarized data; wherein the first and second polarized pilot components belong to a pilot signal that has a pilot frequency that is within a frequency gap formed in a data spectrum that comprises frequencies of the first and second polarized data; wherein the first polarized data and the first polarized pilot components are polarized by a first polarization and wherein the second polarized data and the second polarized pilot components are polarized by a second polarization that differs from the first polarization; coherently summing, by a pilot generator, the first and second polarized pilot components and generating first and second reconstructed pilot signals of substantially a same power; receiving, by a first coherent detector, at least a first portion of the first reconstructed pilot signal and the first polarized data; outputting, by the first coherent detector and in response to the at least first portion of the first reconstructed pilot signal and the first polarized data, at least one first data stream; receiving, by a second coherent detector, at least a first portion of the second reconstructed pilot signal and the second polarized data; outputting, by the second coherent detector and in response to the at least first portion of the second rec

Assignees

• Technion Res & Dev Foundation

Inventors

• Nazarathy Moshe
• Agmon Amos
• Tolmachev Alex

Classifications

• H04B10/63

  Homodyne {, i.e. coherent receivers where the local oscillator is locked in frequency and phase to the carrier signal} · CPC title

• H04B10/64

  Heterodyne {, i.e. coherent receivers where, after the opto-electronic conversion, an electrical signal at an intermediate frequency [IF] is obtained} · CPC title

• H04B10/614

  comprising one or more polarization beam splitters, e.g. polarization multiplexed [PolMux] X-PSK coherent receivers, polarization diversity heterodyne coherent receivers (H04J14/06 takes precedence) · CPC title

• H04B10/6151 Primary

  comprising a polarization controller at the receiver's input stage · CPC title

• H04B10/67

  Optical arrangements in the receiver · CPC title