Multi-aperture beam steering system with wavefront correction based on a tunable optical delay line

• US 6,891,987 B2
• Filed: 04/11/2003
• Issued: 05/10/2005
• Est. Priority Date: 04/24/2002
• Status: Expired due to Fees

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Ionov, Stanislav I., Sumida, David S.
• Primary Examiner(s): Ullah, Akm Enayet
• Assistant Examiner(s): Petkovsek, Daniel
• Application Number:
  US10/411,994
• Publication Number:
  US 20030202731A1
• Time in Patent Office: 760 Days
• Field of Search: 359/263, 359/316, 359/318, 359/572, 385/3, 385/15, 385/27, 385/37, 342/368, 342/375
• US Class Current: 385/15
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: H01Q 3/2676 Optically controlled phased array
• CPC Class Codes: H01Q 3/2682 Time delay steered arrays
• CPC Class Codes: H04B 10/1121 One-way transmission

Abstract

A true-time delay feeder for multiple aperture beam steering devices. The feeder comprises a plurality of tunable time delay modules. The tunable time delay modules provide different delays to different beamlets without changing the spectrum of each beamlet. The tunable true-time delay modules provide for temporal synchronization and spatial coherence of the beam front.

Claims

1. An optical true-time delay generator apparatus for multiple aperture beam steering, said apparatus comprising:

means for splitting a time varying signal from an optical source into a plurality of

beamlets; and

means for true-time delaying said plurality of beamlets, said means for true-time delaying comprising;

means for providing a reflection point for each of said plurality of beamlets, said means for providing a reflection point providing a plurality of reflected beamlets; and

means for continuously adjusting said reflection point.

2. The optical true-time delay generator apparatus of claim 1 wherein said means for true-time delaying said plurality of beamlets further comprises a means for phase tuning said plurality of reflected beamlets.

3. The optical true-time delay generator apparatus of claim 2 wherein said means for phase tuning comprises a fiber mounted on a piezo stretcher, a temperature controlled section of fiber, or a phase controlled fiber amplifier.

4. The optical true-time delay generator apparatus of claim 1 further comprising a means for correcting dispersion in said beamlets, said means for correcting dispersion receiving said time varying signal and providing a dispersion corrected time varying signal to said means for splitting.

5. The optical true-time delay generator apparatus of claim 4 wherein said means for correcting dispersion comprises a chirped distributed Bragg reflector coupled to a directional coupler.

6. The optical true-time delay generator apparatus of claim 1 further comprising means for correcting dispersion in said beamlets, said means for correcting dispersion receiving at least one beamlet from said splitting means and providing at least one dispersion corrected beamlet to said means for true-time delaying.

7. The optical true-time delay generator apparatus of claim 1 further comprising a plurality of means for correcting dispersion in said plurality of reflected beamlets, each of said means for correcting dispersion receiving at least one reflected beamlet from said means for true-time delaying.

8. The optical true-time delay generator apparatus of claim 1 further comprising a means for radiating said plurality of reflected beamlets.

9. The optical true-time delay generator apparatus of claim 1 wherein said means for providing a reflection point comprises a chirped distributed Bragg reflector, said means for adjusting said reflection point comprises a stretcher/compressor coupled with the chirped distributed Bragg reflector, and said means for true-time delaying further comprises a directional coupler coupled with said chirped distributed Bragg reflector.

10. The optical true-time delay generator apparatus of claim 9 wherein said directional coupler comprises an optical circulator.

11. The optical true-time delay generator apparatus of claim 1 wherein said means for splitting comprises a star coupler.

12. The optical true-time delay generator apparatus of claim 1 further comprising a means for amplifying said plurality of reflected beamlets.

13. A method for true-time delaying an optical signal for use in multiple aperture beam steering, said method comprising:

splitting a time varying signal into a plurality of beamlets;

adjusting a reflection point of each of said plurality of beamlets resulting in a plurality of reflected true-time delayed beamlets; and

wherein each reflection point may be adjusted independently and continuously.

14. The method of claim 13 further comprising compensating for dispersion created in said plurality of reflected true-time delayed beamlets.

15. The method of claim 14 wherein said compensating for dispersion further comprises adjusting a chirped distributed Bragg reflector coupled to a directional coupler.

16. The method of claim 13 further comprising increasing the spatial coherence of at least one of said plurality of reflected true-time delayed beamlets.

17. The method of claim 16 wherein said increasing the spatial coherence further comprises phase tuning at least one of said plurality of reflected true-time delayed beamlets.

18. The method of claim 17 wherein said phase tuning further comprises mounting a fiber on a piezo stretcher, temperature controlling a section of fiber or phase controlling a fiber amplifier.

19. The method of claim 13 wherein said adjusting a reflection point further comprises:

providing a chirped distributed Bragg reflector coupled with a directional coupler for receiving at least one of said plurality of beamlets; and

adjusting the chirped distributed Bragg reflector.

20. The method of claim 19 wherein said directional coupler is an optical circulator.

21. The method of claim 13 further comprising amplifying at least one of said plurality of reflected true-time delayed beamlets.

22. The method of claim 13 further comprising transmitting at least one of said plurality of reflected true-time delayed beamlets from an optical radiating element.

23. A system comprising:

a beam splitter having a beam splitter input and a plurality of beam splitter outputs, said beam splitter receiving a time varying signal from an optical source, said beam splitter producing a plurality of beamlets; and

a plurality of continuously tunable true-time delay modules, each tunable true-time delay module being coupled with one of said beam splitter outputs, said plurality of tunable true-time delay modules producing a plurality of reflected true-time delayed beamlets,

wherein each of said plurality of tunable true-time delay modules comprises a first adjustable chirped distributed Bragg reflector.

24. The system of claim 23 wherein at least one of said plurality of tunable true-time delay modules further comprises:

a first directional coupler coupled with said first chirped distributed Bragg reflector; and

a means for adjusting the first chirped distributed Bragg reflector, said means being coupled with said first chirped distributed Bragg reflector.

25. The system of claim 24 wherein at least one of said plurality of tunable true-time delay modules further comprises a phase tuning element coupled with said first directional coupler.

26. The system of claim 25 wherein said phase tuning element is a fiber mounted on a piezo stretcher, a temperature controlled section of a fiber or a phase controlled fiber amplifier.

27. The system of claim 24 wherein said first directional coupler is a first optical circulator.

28. The system of claim 23 further comprising a dispersion compensation module having a dispersion compensation input and a dispersion compensation output, said dispersion compensation input being coupled with said optical source and said dispersion compensation output being coupled with said beam splitter input.

29. The system of claim 28 wherein said dispersion compensation module comprises:

a second optical circulator; and

a second chirped distributed Bragg reflector coupled with said second optical circulator.

30. The system of claim 23 further comprising a plurality of dispersion compensation modules, each dispersion compensation module being coupled with one of said plurality of tunable true time delay modules.

31. The system of claim 23 wherein said beam splitter comprises a star coupler.

32. The system of claim 23 further comprising a plurality of amplifiers, at least one of said plurality of amplifiers being coupled with at least one of said plurality of tunable true-time delay modules.

33. The system of claim 23 further comprising a plurality of radiating elements, said plurality of radiating elements radiating said reflected true-time delayed beamlets.

34. A multi-aperture beam steering system comprising:

a dispersion compensation module for receiving a train of optical pulses and providing a train of dispersed pulses;

a coupler having a coupler input and a plurality of outputs, said coupler receiving said train of dispersed pulses; and

a plurality of continuously tunable true-tune delay modules, each tunable true-time delay module having an input and an output, said input of each of said plurality of tunable true-time delay modules connected to at least one of said outputs of said coupler,

wherein each tunable true-time delay module comprises an adjustable chirped distributed Bragg reflector.

35. The multi-aperture beam steering system of claim 34 wherein said coupler is a star coupler.

36. The multi-aperture beam steering system of claim 34 wherein each tunable true-time delay module further comprises:

an optical circulator, having a first delay port, a second delay port and a third delay port wherein said first delay port is said input of said tunable true-time delay module, said chirped distributed Bragg reflector being connected to said second delay port

of said optical circulator;

a means for adjusting said chirped distributed Bragg reflector, said means for adjusting being coupled to said chirped distributed Bragg reflector; and

a phase tuning element, having a phase input and a phase output, said phase input connected to said third delay port of said optical circulator, and wherein said output of said tunable true-time delay module is said phase output.

37. The multi-aperture beam steering system of claim 36 wherein said phase tuning element is a fiber mounted on a piezo stretcher.

38. The multi-aperture beam steering system of claim 34 wherein said dispersion compensation module comprises:

an optical circulator, having a first dispersion port, a second dispersion port and a third dispersion port, wherein said first dispersion port receives said train of optical pulses, and said third dispersion port provides said train of dispersed pulses; and

a chirped distributed Bragg reflector connected with said second dispersion port of said optical circulator.

39. A sequential true-time delay system comprising:

an optical source, having a source output;

a dispersion compensation module comprising;

a first optical circulator, having a first dispersion port, a second dispersion port and a third dispersion port, wherein said first dispersion port of said first optical circulator is connected with said source output; and

a first chirped distributed Bragg reflector connected with said second dispersion port of said first optical circulator;

a star coupler having a star input and a plurality of outputs, said star input connected to said third dispersion port of said first optical circulator; and

a plurality of tunable true-time delay modules, each tunable true-time delay module comprising;

a second optical circulator, having a first delay port, a second delay port and a third delay port, wherein said first delay port of said second optical circulator is connected with one of said plurality of outputs of said star coupler;

a second chirped distributed Bragg reflector grating connected with said second delay port of said second optical circulator;

a means for adjusting said chirped distributed Bragg reflector, said means for adjusting being coupled to said chirped distributed Bragg reflector; and

a phase control element having a phase input and a phase output, said phase input connected to said third delay port of said second optical circulator.

40. An optical true-time delay generator apparatus for multiple aperture beam steering, said apparatus comprising:

means for splitting a time varying signal from an optical source into a plurality of beamlets; and

means for true-time delaying said plurality of beamlets, said means for true-time delaying comprising;

means for providing a reflection point for each of said plurality of beamlets, said means for providing a reflection point providing a plurality of reflected beamlets; and

means for adjusting said reflection point,

wherein said means for true-time delaying said plurality of beamlets further comprises a means for phase tuning said plurality of reflected beamlets, said means for phase tuning comprising a fiber mounted on a piezo stretcher, a temperature controlled section of fiber, or a phase controlled fiber amplifier.

41. An optical true-time delay generator apparatus for multiple aperture beam steering, said apparatus comprising:

means for splitting a time varying signal from an optical source into a plurality of beamlets; and

means for true-time delaying said plurality of beamlets, said means for true-time delaying

comprising;

means for providing a reflection point for each of said plurality of beamlets, said means for providing a reflection point providing a plurality of reflected beamlets; and

means for adjusting said reflection point,

wherein said means for providing a reflection point comprises a chirped distributed Bragg reflector, said means for adjusting said reflection point comprises a stretcher/compressor coupled with the chirped distributed Bragg reflector, and said means for true-time delaying further comprises a directional coupler coupled with said chirped distributed Bragg reflector.

42. The optical true-time delay generator apparatus of claim 41 wherein said directional coupler comprises an optical circulator.

43. A method for true-time delaying an optical signal for use in multiple aperture beam steering, said method comprising:

splitting a time varying signal into a plurality of beamlets;

adjusting a reflection point of each of said plurality of beamlets resulting in a plurality of reflected true-time delayed beamlets, wherein each reflection point may be adjusted independently; and

phase tuning at least one of said plurality of reflected true-time delayed beamlets, wherein said phase tuning is provided by mounting a fiber on a piezo stretcher, temperature controlling a section of fiber or phase controlling a fiber amplifier.

44. A system comprising:

a beam splitter having a beam splitter input and a plurality of beam splitter outputs, said beam splitter receiving a time varying signal from an optical source, said beam splitter producing a plurality of beamlets; and

a plurality of tunable true-time delay modules, each tunable true-time delay module being coupled with one of said beam splitter outputs, said plurality of tunable true-time delay modules producing a plurality of reflected true-time delayed beamlets,

wherein each of said plurality of tunable true-time delay modules comprises a first chirped distributed Bragg reflector, and

wherein at least one of said plurality of tunable true-time delay modules further comprises;

a first directional coupler coupled with said first chirped distributed Bragg reflector; and

a means for adjusting the first chirped distributed Bragg reflector, said means being coupled with said first chirped distributed Bragg reflector; and

a phase tuning element coupled with said first directional coupler, wherein said phase tuning element is a fiber mounted on a piezo stretcher, a temperature controlled section of a fiber or a phase controlled fiber amplifier.

45. A multi-aperture beam steering system comprising:

a dispersion compensation module for receiving a train of optical pulses and providing a train of dispersed pulses;

a coupler having a coupler input and a plurality of outputs, said coupler receiving said train of dispersed pulses; and

a plurality of tunable true-time delay modules, each tunable true-time delay module having an input and an output, said input of each of said plurality of tunable true-time delay modules connected to at least one of said outputs of said coupler,

wherein each tunable true-time delay module comprises;

a chirped distributed Bragg reflector,

an optical circulator, having a first delay port, a second delay port and a third delay port wherein said first delay port is said input of said tunable true-time delay module, said chirped distributed Bragg reflector being connected to said second delay port of said optical circulator;

a means for adjusting said chirped distributed Bragg reflector, said means for adjusting being coupled to said chirped distributed Bragg reflector; and

a phase tuning element, having a phase input and a phase output, said phase input connected to said third delay port of said optical circulator, and wherein said output of said tunable true-time delay module is said phase output.

46. The multi-aperture beam steering system of claim 45 wherein said phase tuning element is a fiber mounted on a piezo stretcher.