Granted Patent B2

US 7,002,724 · App. 10/874,594 · Granted Feb 21, 2006

Abstract

Claims (26)

1. An apparatus for generating a 90° alternate phase (AP) optical pulsetrain, comprising:

a phase-modulated optical signal generator configured to generate a phase-modulated optical signal having a carrier band and sidebands phase-shifted relative thereto by multiples of 90°; and

an optical filter coupled to said phase-modulated optical signal generator and configured to 180° phase-shift selected ones of said carrier band and sidebands to generate said 90° AP optical pulsetrain.

2. The apparatus as recited in claim 1 wherein said phase-modulated optical signal generator comprises an electro-optical phase modulator driven at half a desired pulse frequency of said 90° AP optical pulsetrain.

3. The apparatus as recited in claim 1 wherein said phase-modulated optical signal generator is a modulated laser light source.

4. The apparatus as recited in claim 1 wherein said optical filter is an all-pass filter having at least one stage.

5. The apparatus as recited in claim 1 wherein said optical filter is at least one Fabry-Perot filter.

6. The apparatus as recited in claim 1 wherein said optical filter 180° phase-shifts either said carrier band or at least two of said sidebands and has a free spectral range at least three times a spacing of said carrier band and sidebands.

7. The apparatus as recited in claim 1 wherein said 90° AP optical pulsetrain has a pulse frequency of about 40 GHz.

8. A method of generating a 90° alternate phase (AP) optical pulsetrain, comprising:

generating a phase-modulated optical signal having a carrier band and sidebands phase-shifted relative thereto by multiples of 90°; and

180° phase-shifting selected ones of said carrier band and sidebands.

9. The method as recited in claim 8 wherein said generating comprises driving an electro-optical phase modulator at half a desired pulse frequency of said 90° AP optical pulsetrain.

10. The method as recited in claim 8 wherein said generating comprises exciting a modulated laser light source.

11. The method as recited in claim 8 wherein said 180° phase-shifting is carried out in an all-pass filter having at least one stage.

12. The method as recited in claim 8 wherein 180° phase-shifting is carried out in at least one Fabry-Perot filter.

13. The method as recited in claim 8 wherein said 180° phase-shifting comprises 180° phase-shifting either said carrier band or at least two of said sidebands with an optical filter having a free spectral range at least three times a spacing of said carrier band and sidebands.

14. The method as recited in claim 8 wherein said 90° AP optical pulsetrain has a pulse frequency of about 40 GHz.

15. An apparatus for generating a 90° alternate phase (AP) optical pulsetrain, comprising:

a phase-modulated optical signal generator including an electro-optical phase, said phase-modulated optical signal generator configured to generate a phase-modulated optical signal having a carrier band and sidebands phase-shifted relative thereto by multiples of 90°; and

an optical filter coupled to said phase-modulated optical signal generator and configured to 180° phase-shift selected ones of said carrier band and sidebands to generate an 90° AP optical pulsetrain having a pulse frequency of about 40 GHz.

16. The apparatus as recited in claim 15 wherein said optical filter is an all-pass filter having at least one stage.

17. The apparatus as recited in claim 15 wherein said optical filter is at least one Fabry-Perot filter.

18. The apparatus as recited in claim 15 wherein said optical filter 180° phase-shifts either said carrier band or at least two of said sidebands.

19. The apparatus as recited in claim 15 wherein said optical filter has a free spectral range at least three times a spacing of said carrier band and sidebands.

20. The apparatus as recited in claim 15 wherein said optical filter comprises first and second stages having ring resonators.

Assignments (9)