High signal to noise ratio optical signal processing system

• US 5,400,038 A
• Filed: 09/25/1992
• Issued: 03/21/1995
• Est. Priority Date: 06/18/1992
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Martin Marietta Corporation
• Inventors: Riza, Nabeel A., DeJule, Michael C.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US07/950,554
• Time in Patent Office: 907 Days
• Field of Search: 342/368, 342/375, 359/629, 359/638, 359/639, 359/640, 250/227.12, 385/11, 385/36, 385/31, 385/32
• US Class Current: 342/375
• CPC Class Codes: H01Q 3/2676 Optically controlled phased array

Abstract

An optical signal processing system includes a number of optical time delay units to generate differentially time-delayed optical signals. Each optical time delay unit includes at least an in put polarizing beam splitter (PBS) system having an input system Thompson prism and an output PBS system including an output Thompson prism. Each Thompson prism has a high extinction ratio and is positioned to act as a polarizing beam splitter, providing a high signal to noise ratio optical signal processing system. Selectively polarized light beams are deflected by the polarizing beam splitters onto predetermined paths that cause the respective light beams to be differentially time delayed dependent on the path that they follow through the optical signal processing system.

Claims

1. An optical time delay unit comprising:

a delay assembly;

an input polarizing beam splitter (PBS) system disposed to receive incident light beams and direct respective ones of said beams along a respective delay path or a respective direct path dependent on the polarization of the respective light beams;

said input PBS system including at least one input system Thompson prism and means for optically coupling said input PBS system to said delay assembly; and

an output PBS system disposed to receive light beams passing along respective ones of said delay paths and respective ones of said direct paths, said output PBS system including at least one output system Thompson prism and means for optically coupling said output PBS system to said delay assembly,

said input PBS system and said output PBS system being optically coupled together such that light beams pass therebetween along respective ones of said direct paths.

2. The optical time delay unit of claim 1 wherein:

said means for optically coupling said input PBS system to said delay assembly comprises a second input Thompson prism disposed to receive light beams deflected by said at least one input Thompson prism towards said delay path such that the deflected light beams are further deflected by said second Thompson prism and coupled to said delay unit.

3. The optical time delay unit of claim 1 wherein:

said means for optically coupling said input PBS system to said delay assembly comprises an input PBS system mirror disposed to receive light beams deflected by said at least one input Thompson prism towards said delay path such that the deflected light beams are further deflected by said input PBS system mirror and coupled to said delay unit.

4. The optical time delay unit of claim 1 wherein:

said means for optically coupling said output PBS system to said delay assembly comprises a second output Thompson prism coupled to said delay assembly to receive light beams passing therefrom such that light beams having the polarization selected to pass along said delay path are deflected to pass into said at least one output Thompson prism.

5. The optical time delay unit of claim 2 wherein:

said means for optically coupling said output PBS system to said delay assembly comprises a second output Thompson prism coupled to said delay assembly to receive light beams passing therefrom such that light beams having the polarization selected to pass along said delay path are deflected to pass into said at least one output Thompson prism.

6. The optical time delay unit of claim 1 wherein:

said means for optically coupling said output PBS system to said delay assembly comprises an output PBS system mirror disposed to receive light beams passing along said delay path from said delay assembly such that the light beams are deflected by said output PBS system mirror into said at least one output Thompson prism.

7. The optical time delay unit of claim 2 wherein:

said means for optically coupling said output PBS system to said delay assembly comprises an output PBS system mirror disposed to receive light beams passing along said delay path from said delay assembly such that the light beams are deflected by said output PBS system mirror into said at least one output Thompson prism.

8. The optical delay unit of claim 2 wherein:

each of the Thompson prisms has a direct-pass-through axis and a light deflection axis having a light deflection angle with respect to said direct-pass-through axis of about 45°

, and

said second input Thompson prism is disposed such that the second input Thompson prism direct-pass-through axis is substantially aligned with the at least one input Thompson prism light deflection axis.

9. The optical delay unit of claim 4 wherein:

each of the Thompson prisms has a direct-pass-through axis and a light deflection axis having a light deflection angle with respect to said light entry/pass-through axis of about 45°

, and

said second output Thompson prism is disposed such that the second output Thompson prism deflection axis is substantially aligned with the at least one output Thompson prism light deflection axis.

10. The device of claim 1 wherein said delay assembly comprises a free space delay unit.

11. The device of claim 1 wherein said delay assembly comprises an optical fiber array, an input focussing lens array, and an output collimating lens army, said input focussing lens array being disposed to optically couple said input PBS system to said optical fiber array, and said output collimating lens array being disposed to optically couple said optical fiber array to said output PBS system.

12. An optical signal processing system comprising:

an input pixel array having a predetermined input array pattern;

an output pixel array having a predetermined output array pattern, said output army pattern corresponding to said input array pattern; and

an optical time delay unit disposed to optically couple said input pixel array to said output pixel array so that light beams passing from predetermined ones of the pixels in said input pixel army will enter corresponding ones of the pixels in said output pixel array, whereby each of said light beams will pass along a respective delay path or a respective direct path in said optical time delay unit dependent on the polarization of the light beam;

said optical time delay unit comprising an input polarizing beam splitter (PBS) system having at least one input Thompson prism, an output PBS system having at least one output Thompson prism, and means for optically coupling said at least one input Thompson prism to said delay assembly.

13. The system of claim 12 wherein said means for optically coupling said at least one input Thompson prism to said delay assembly comprises a second input Thompson prism disposed to receive light beams deflected towards said delay path by said at least one input Thompson prism such that the deflected light beams having the selected polarization to pass along said delay path are further deflected by said second Thompson prism onto a path to pass into said delay assembly.

14. The system of claim 12 wherein:

said means for optically coupling said at least one input Thompson prism to said delay assembly comprises an input PBS system mirror disposed to receive light beams deflected towards said delay path by said at least one input Thompson prism such that light beams incident on said input PBS system mirror are further deflected onto a path to pass into said delay assembly.

15. The system of claim 12 wherein said means for optically coupling said delay assembly to said at least one output Thompson prism comprises a second output Thompson prism disposed such that light beams passing from said delay assembly are incident on said second output Thompson prism and light beams having the selected polarization for passing along said delay path are deflected into said at least one output Thompson prism.

16. The system of claim 13 wherein:

said means for optically coupling said output PBS system to said delay assembly comprises an output PBS system mirror disposed to receive light beams passing from said delay assembly such that the light beams are deflected by said output PBS system mirror into said at least one output Thompson prism.

17. The optical delay unit of claim 13 wherein:

each of the Thompson prisms has a direct-pass-through axis and a light deflection axis having a light deflection angle with respect to said direct-pass-through axis of about 45°

, and

said second input Thompson prism is disposed such that the second input Thompson prism direct-pass-through axis is substantially aligned with the at least one input Thompson prism light deflection axis.

18. The optical delay unit of claim 15 wherein:

each of the Thompson prisms has a direct-pass-through axis and a light deflection axis having a light deflection angle with respect to said direct-pass-through axis of about 45°

, and

said second output Thompson prism is disposed such that the second output Thompson prism light deflection axis is substantially aligned with the at least one output Thompson prism light deflection axis.

19. The system of claim 12 wherein said input pixel array and said output pixel array each comprises at least two independently controllable patterns of pixels arranged to pass at least a first and a second channel of light beams, each of said channels comprising a corresponding plurality of light beams.

20. In combination, the optical signal processing system of claim 12 and:

a plurality of antenna elements arranged in an array; and

an optoelectronic transceiver array coupled to said optical signal processing system and said antenna army to convert optical signals passing to said antenna array into electrical signals and to convert electrical signals passing from said antenna array into optical signals;

said optical signal processing system being coupled to the antenna array and adapted to generate differentially time-delayed optical signals to control antenna array radiation patterns.