Low power optical transceiver using orthogonal polarization detection technique

Patent metadata

Field	Value
Publication number	US-8977125-B2
Application number	US-85466810-A
Country	US
Kind code	B2
Filing date	Aug 11, 2010
Priority date	Aug 11, 2010
Publication date	Mar 10, 2015
Grant date	Mar 10, 2015

Abstract

A method and apparatus for simultaneous processing of signals impressed on a horizontal polarization of a light wave and on a vertical polarization of the light wave is provided. In one embodiment, a horizontal polarization pilot tone is impressed on a data signal carried by the horizontal polarization and a vertical polarization pilot tone is impressed on a data signal carried by the vertical polarization. A receiver processes the dual-polarized light wave and converts it to an X channel signal and a Y channel signal. The X and Y channel signals are processed in separate channels to recover a phase and frequency offset between them and a local oscillator. The phase and frequency recovered and frequency de-multiplexed signals are further processed to polarization de-multiplex the data signal carried by the horizontal polarization and the data signal carried by the vertical polarization.

First claim

What is claimed is:

1. A method of performing Orthogonal Polarization Detection, the method comprising:
receiving an optical transmission signal having a first signal associated with a horizontal light wave polarization and a second signal associated with a vertical light wave polarization, the first signal having a horizontal polarization pilot tone, and the second signal having a vertical polarization pilot tone, a spectrum of the first signal and a spectrum of the horizontal polarization pilot tone being offset in frequency from a spectrum of the second signal and a spectrum of the vertical polarization pilot tone;
processing the received optical transmission signal by selecting the horizontal polarization pilot tone and selecting the vertical polarization pilot tone and recovering a phase and frequency recovered first signal associated with the horizontal light wave polarization and a phase and frequency recovered second signal associated with the vertical light wave polarization, wherein processing the received optical transmission signal comprises splitting the received optical transmission signal into a first channel signal and a second channel signal; and
using a vertical polarization pilot tone and a horizontal polarization pilot tone from the first channel signal to produce a first horizontal phase and frequency recovered signal and a first vertical phase and frequency recovered signal and using a vertical polarization pilot tone and a horizontal polarization pilot tone from the second channel signal to produce a second horizontal phase and frequency recovered signal and a second vertical phase and frequency recovered signal.

2. The method of claim 1 , wherein processing the received optical transmission signal comprises:
beam splitting the received optical transmission signal and mixing the received optical transmission signal with an optical local oscillator signal to produce an X channel signal and a Y channel signal.

3. The method of claim 2 , wherein processing the received optical transmission signal comprises:
filtering the X channel signal by a first filter to select an X channel horizontal polarization pilot tone, complex-conjugating the selected X channel horizontal polarization pilot tone, and multiplying the complex-conjugated selected X channel horizontal polarization pilot tone by the X channel signal to select the X channel horizontal polarization pilot tone from the X channel signal to produce a phase and frequency recovered horizontal X channel signal; and
filtering the X channel signal by a second filter to select an X channel vertical polarization pilot tone, complex-conjugating the selected X channel vertical polarization pilot tone, and multiplying the complex-conjugated selected X channel vertical polarization pilot signal by the X channel signal to select the vertical polarization pilot tone from the X channel signal to produce a phase and frequency recovered vertical X channel signal.

4. The method of claim 3 , wherein processing the received optical transmission signal further comprises:
filtering the Y channel signal by a third filter to select a Y channel horizontal polarization pilot tone, complex-conjugating the selected Y channel horizontal polarization pilot tone, and multiplying the complex-conjugated selected Y channel horizontal polarization pilot tone by the Y channel signal to select the Y channel horizontal polarization pilot tone from the Y channel signal to produce a phase and frequency recovered horizontal Y channel signal; and
filtering the Y channel signal by a fourth filter to select a Y channel vertical polarization pilot tone, complex-conjugating the selected Y channel vertical polarization pilot tone, and multiplying the complex-conjugated selected Y channel vertical polarization pilot signal by the X channel signal to select the vertical polarization pilot tone from the Y channel signal to produce a phase and frequency recovered vertical Y channel signal.

5. The method of claim 4 , wherein processing the received optical transmission signal further comprises:
adding the phase and frequency recovered horizontal X channel signal to the phase and frequency recovered horizontal Y channel signal to produce the first signal associated with the horizontal light wave polarization; and
adding the phase and frequency recovered vertical X channel signal to the phase and frequency recovered vertical Y channel signal to produce the second signal associated with the vertical light wave polarization.

6. The method of claim 1 , further comprising recovering the first signal by adding the first horizontal phase and frequency recovered signal and the second horizontal phase and frequency recovered signal, and recovering the second signal by adding the first vertical phase and frequency recovered signal and the second vertical phase and frequency recovered signal.

7. The method of claim 1 , wherein the offset between the spectrum of the horizontal polarization pilot tone and the spectrum of the vertical polarization pilot tone is less than 5% of a bandwidth of the first signal or the second signal.

8. The method of claim 1 , wherein the offset between the spectrum of the horizontal polarization pilot tone and the spectrum of the vertical polarization pilot tone is less than 2% of a bandwidth of the first signal or the second signal.

9. A method of Orthogonal Polarization Multiplexing, the method comprising: forming an optical transmission signal having a first signal associated with a horizontal light wave polarization and a second signal associated with a vertical light wave polarization, the first signal having a horizontal polarization pilot tone, and the second signal having a vertical polarization pilot tone, the first signal having a spectrum that is offset in frequency from a spectrum of the second signal, and the horizontal polarization pilot tone having a spectrum that is offset in frequency from a spectrum of the vertical polarization pilot tone;
processing the optical transmission signal by selecting the horizontal polarization pilot tone and selecting the vertical polarization pilot tone and recovering a phase and frequency recovered first signal associated with the horizontal light wave polarization and a phase and frequency recovered second signal associated with the vertical light wave polarization, wherein processing the optical transmission signal comprises splitting the received optical transmission signal into a first channel signal and a second channel signal;
using a vertical polarization pilot tone and a horizontal polarization pilot tone from the first channel signal to produce a first horizontal phase and frequency recovered signal and a first vertical phase and frequency recovered signal and using a vertical pilot tone and a horizontal pilot tone from the second channel signal to produce a second horizontal phase and frequency recovered signal and a second vertical phase and frequency recovered signal; and
wherein processing the optical transmission signal comprises:
beam splitting the optical transmission signal and mixing the optical transmission signal with an optical local oscillator signal to produce an X channel signal and a Y channel signal; and
filtering the X channel signal by a first filter to select an X channel horizontal polarization pilot tone, complex-conjugating the selected X channel horizontal polarization pilot tone, and multiplying the complex-conjugated selected X channel horizontal polarization pilot tone by the X channel signal to select the X channel horizontal polarization pilot tone from the X channel signal to produce a phase and frequency recovered horizontal X channel signal; and filtering the X channel signal by a second filter to select an X cha

Assignees

• Grigoryan Vladimir S
• Pelekhaty Vladimir
• Frankel Michael Y
• Ciena Corp

Inventors

• Grigoryan Vladimir S
• Pelekhaty Vladimir
• Frankel Michael Y

Classifications

• H04B10/613

  including phase diversity, e.g., having in-phase and quadrature branches, as in QPSK coherent receivers · CPC title

• H04B10/548

  Phase or frequency modulation · CPC title

• H04B10/5053

  using a parallel, i.e. shunt, combination of modulators · CPC title

• H04J14/06 Primary

  Polarisation multiplex systems · CPC title

• H04B10/65

  Intradyne, i.e. coherent receivers with a free running local oscillator having a frequency close but not phase-locked to the carrier signal · CPC title