Optical QPSK signal regeneration and amplification

1. A method for regenerating and amplifying optical signals, comprising:

determining a source optical signal;

adding a first pump optical signal and a second pump optical signal to the source optical signal to yield an intermediate optical signal;

duplicating the intermediate optical signal to yield a first duplicate signal and a second duplicate signal;

phase-shifting the first duplicate signal;

passing the phase-shifted first duplicate signal and the second duplicate signal bi-directionally through a first nonlinear optical element; and

performing degenerate phase-sensitive amplification on the phase-shifted first duplicate signal and the second duplicate signal.

2. The method of claim 1 , wherein:

the difference between a wavelength of the first pump optical signal and a wavelength of the source optical signal comprises a first wavelength distance;

the difference between a wavelength of the second pump optical signal and a wavelength of the source optical signal comprises a second wavelength distance; and

the first wavelength distance and the second wavelength distance are approximately equal.

3. The method of claim 1 , wherein the source optical signal includes a quadrature phase-shift-keying (“QPSK”) modulated signal.

4. The method of claim 1 , wherein the source optical signal includes a dual-polarized QPSK (“DP-QPSK”) modulated signal.

5. The method of claim 4 , further comprising:

separating the intermediate signal into an x-polarization component and a y-polarization component;

performing degenerate phase-sensitive amplification for the x-polarization component, wherein duplicating the intermediate optical signal includes duplicating the x-polarization component to yield the first duplicate signal and the second duplicate signal;

performing degenerate phase-sensitive amplification for the y-polarization component, comprising:

duplicating the y-polarization component to yield a third duplicate signal and a fourth duplicate signal;

phase-shifting the third duplicate signal; and

passing the phase-shifted third duplicate signal and the fourth duplicate signal bi-directionally through a second nonlinear optical element.

6. The method of claim 4 , further comprising:

separating the first duplicate signal into a first x-polarization component and a first y-polarization component;

separating the second duplicate signal into a second x-polarization component and a second y-polarization component;

performing degenerate phase-sensitive amplification for the x-polarization components, wherein passing the phase-shifted first duplicate signal and the second duplicate signal bi-directionally through the first nonlinear optical element includes passing the first x-polarization component and the second x-polarization component bi-directionally through the first nonlinear optical element; and

performing degenerate phase-sensitive amplification for the y-polarization components, comprising passing the first y-polarization component and the second y-polarization component bi-directionally through a second nonlinear optical element.

7. The method of claim 1 , wherein performing degenerate phase-sensitive amplification comprises performing four-wave mixing utilizing the phase-shifted first duplicate signal and the second duplicate signal.

8. The method of claim 1 , wherein:

performing degenerate phase-sensitive amplification on the phase-shifted first duplicate signal comprises performing degenerate phase-shift amplification on the real portion of the source optical signal; and

performing degenerate phase-sensitive amplification on the second duplicate signal comprises performing degenerate phase-shift amplification on the imaginary portion of the source optical signal.

9. The method of claim 1 , wherein the first duplicate signal is phase-shifted by 90°.

10. The method of claim 1 , wherein the phase-shifted first duplicate signal and the second duplicate signal are simultaneously passed bi-directionally through the first nonlinear optical element.

11. A system for regenerating optical signals, comprising:

an input configured to accept a source optical signal;

a dual-pump source configured to generate a first pump optical signal and a second pump optical signal;

a coupler communicatively coupled to the input and the dual-pump source configured to add the first pump optical signal and the second pump optical signal to the source optical signal to yield an intermediate optical signal;

a first wavelength selective processor configured to accept the intermediate optical signal;

a first nonlinear optical element communicatively coupled at two ends to the first wavelength selective processor;

wherein the first wavelength selective processor is configured to:

duplicate the intermediate optical signal to yield a first duplicate signal and a second duplicate signal;

phase-shift the first duplicate signal; and

send the phase-shifted first duplicate signal and the second duplicate signal through the first nonlinear optical element in opposite directions;

wherein the first nonlinear optical element is configured to perform degenerate phase-sensitive amplification on the phase-shifted first duplicate signal and the second duplicate signal; and

wherein the first wavelength selective processor includes a wavelength selective switch.

12. The system of claim 11 , wherein:

the difference between a wavelength of the first pump optical signal and a wavelength of the source optical signal comprises a first wavelength distance;

the difference between a wavelength of the second pump optical signal and a wavelength of the source optical signal comprises a second wavelength distance; and

the first wavelength distance and the second wavelength distance are approximately equal.

13. The system of claim 11 , wherein the source optical signal includes a QPSK modulated signal.

14. The system of claim 11 , wherein the source optical signal includes a DP-QPSK modulated signal.

15. The system of claim 14 , further comprising:

a beam splitter communicatively coupled between the coupler and the first wavelength selective processor configured to separate the intermediate signal into an x-polarization component and a y-polarization component;

a second wavelength selective processor communicatively coupled to the beam splitter, comprising a wavelength selective switch;

a second optical nonlinear element communicatively coupled at two ends to the second wavelength selective processor;

wherein:

the beam splitter is configured to send the x-polarization component to the first wavelength selective processor and the y-polarization component to the second wavelength selective processor;

configuring the first wavelength selective processor to duplicate the intermediate optical signal includes configuring the first wavelength selective processor to duplicate the x-polarization component to yield the first duplicate signal and the second duplicate signal;

the second wavelength selective processor is configured to:

duplicate the y-polarization component to yield a third duplicate signal and a fourth duplicate signal;

phase-shift the third duplicate signal; and

send the phase-shifted third duplicate signal and the fourth duplicate signal through the first nonlinear optical element in opposite directions; and

the second nonlinear optical element is configured to perform degenerate phase-sensitive amplification on the phase-shifted third duplicate signal and the fourth duplicate signal.

16. The system of claim 14 , further comprising:

a second nonlinear optical element communicatively coupled at two ends to the first wavelength selective processor;

a first beam splitter:

communicatively coupled between the first wavelength selective processor and a first terminal of the first optical nonlinear element and between the first wavelength selective processor and a first terminal the second optical nonlinear element;

configured to separate the phase-shifted first duplicate signal into a first x-polarization component and a first y-polarization component; and

configured to send the first x-polarization component to the first terminal of the first optical nonlinear element and to send the first y-polarization component to the first terminal of the second optical nonlinear element;

a second beam splitter:

communicatively coupled between the first wavelength selective processor and a second terminal of the first optical nonlinear element and between the first wavelength selective processor and a second terminal the second optical nonlinear element;

configured to separate the second duplicate signal into a second x-polarization component and a second y-polarization component; and

configured to send the second x-polarization component to the second terminal of the first optical nonlinear element and to send the second y-polarization component to the second terminal of the second optical nonlinear element;

wherein configuring the first nonlinear optical element to perform degenerate phase-sensitive amplification on the phase-shifted first duplicate signal and the second duplicate signal comprises configuring the first nonlinear optical element to perform degenerate phase-sensitive amplification on the first x-polarization component and the second x-polarization component; and

the second nonlinear optical element is configured to perform degenerate phase-sensitive amplification on the first y-polarization component and the second y-polarization component.

17. The system of claim 11 wherein configuring the first nonlinear optical element to perform degenerate phase-sensitive amplification comprises configuring the first nonlinear optical element to performing four-wave mixing utilizing the phase-shifted first duplicate signal and the second duplicate signal.

18. The system of claim 11 , wherein:

configuring the first nonlinear optical element to perform degenerate phase-sensitive amplification on the phase-shifted first duplicate signal comprises configuring the first nonlinear optical element to perform degenerate phase-shift amplification on the real portion of the source optical signal; and

configuring the first nonlinear optical element to perform degenerate phase-sensitive amplification on the second duplicate signal comprises configuring the first nonlinear optical element to perform degenerate phase-shift amplification on the imaginary portion of the source optical signal.

19. The system of claim 11 , wherein the first wavelength selective processor is configured to phase-shift the first duplicate signal by 90°.

20. The system of claim 11 , wherein the first wavelength selective processor is configured to simultaneously send the phase-shifted first duplicate signal and the second duplicate signal bi-directionally through the first nonlinear optical element.