Computer backplane employing free space optical interconnect

• US 20020089709A1
• Filed: 06/19/2001
• Published: 07/11/2002
• Est. Priority Date: 01/11/2001
• Status: Active Grant

• Current Assignee: Rdm Foundation
• Original Assignee: Rdm Foundation
• Inventors: Mays, Robert Jr.
• Granted Patent: US 6,452,700 B1
• Time in Patent Office: Days
• US Class Current: 359/15
• CPC Class Codes: H04B 10/801 using optical interconnects, e.g. light coupled isolators, circuit board interconnections

Abstract

Provided is an optical backplane interconnect system, one embodiment of which features transceiver subsystems employing holographic optical elements (HOEs) that define, and discriminate between, differing optical channels of communication. The HOEs employ a holograph transform to concurrently refract and filter optical energy to remove optical energy having unwanted characteristics. To that end, the transceiver subsystem is mounted to an expansion card and includes a source of optical energy and an optical detector. The HOE need not be mounted to the expansion cared. In one embodiment, however, the HOE is mounted to the expansion card and in optical communication with either the source of optical energy, the optical detector or both.

Claims

1. A backplane interconnect system comprising:

an expansion slot;

an expansion card in electrical communication with said expansion slot, said expansion card having a source of optical energy to propagate optical energy along an optical path;

a detector positioned in the optical path; and

a holographic optical element having an arcuate surface and a holographic transform function, with said optical element being disposed to filter the optical energy in accordance with properties of the holographic transform function to remove optical energy having unwanted characteristics, defining transformed optical energy, and refract the transformed energy in accordance with properties of said arcuate surface to impinge upon said detector.

2. The system as recited in claim 1 further including an additional expansion slot and an additional expansion card in electrical communication with said additional expansion slot, with said detector being mounted to said additional expansion card to facilitate data communication between said expansion cards.

3. The system as recited in claim 1 further including an additional expansion slot and an additional expansion card, in electrical communication with said additional expansion slot, said detector being mounted to said additional expansion card, and said source of optical energy including an array of optical emitters to generate optical energy to propagate along a plurality of axes and said detector including an array of optical receivers, each of which is positioned to sense optical energy propagating along one of the plurality of optical axes, with said holographic optical element including an array of lenses, each of which is disposed in one of the plurality of axes and includes the arcuate surface with the holographic transform being disposed within a volume of the array of lenses.

4. The system as recited in claim 1 further including an additional expansion slot and an additional expansion card, in electrical communication with said additional expansion slot, with said detector being mounted to said additional expansion card, said source of optical energy including an array of optical emitters to generate optical energy to propagate along a plurality of axes and the detector includes an array of optical receivers, each of which is positioned to sense optical energy propagating along one of the plurality of optical axes, said holographic optical element including a plurality of lenses having the arcuate surface, with said holographic transform function being disposed within a volume thereof, with said plurality of lenses being arranged in first and second arrays, said first array being disposed between said array of optical emitters and said array of optical receivers and said second array being disposed between said first array and the optical receivers.

5. The system as recited in claim 4 wherein the holographic transform function associated with a subgroup of the lenses of the first array differs from the holographic transform function associated with the remaining lenses of the first array of lenses, and the holographic transform function associated with a subset of the lenses of the second array matching the transfer function.

6. The system as recited in claim 1 wherein said source includes semiconductor lasers.

7. The system as recited in claim 1 wherein said detector comprises charge injection devices.

8. The system as recited in claim 1 wherein said holographic optical element further includes a telecentric lens having a bulk hologram recorded therein.

9. The system as recited in claim 1 wherein said holographic optical element further includes a converging lens having a bulk hologram recorded therein.

10. The system as recited in claim 1 further including a processor in data communication with said expansion card slot over a bus with said source producing modulated optical energy in accordance with instructions received from said processor.

13. The systems as recited in claim 11 wherein each of the optical receivers of said first and second array comprises charge injection devices.

20. The system as recited in claim 1 further including a processor in data communication with said first and second expansion card slots over a bus with said optical emitters of said first and second arrays adapted to produce modulated optical energy in accordance with instructions received from said processor.

11. A backplane interconnect system comprising:

first and second expansion slots;

a first expansion card in electrical communication with said first expansion slot, said first expansion card having a first array of optical emitters to generate optical energy to propagate along a plurality of axes and a first array of optical receivers;

a second expansion card in electrical communication with said second expansion slot, said second expansion card having a second array of optical emitters to generate optical energy to propagate along a plurality of paths, and a second array of optical receivers, each of which is positioned to sense optical energy propagating along one of the plurality of optical axes, with the optical receivers of said first optical array positioned to sense optical energy propagating along said plurality of paths; and

a holographic optical element including a plurality of lens elements, each of which has a holographic transform function recorded therein, defining a plurality of holographic transform functions, each of said plurality of detectors being associated with one of said plurality of holographic transform functions, with the holographic transform function associated with one of said plurality of detectors differing from the holographic transform functions associated with the remaining detectors of said plurality of detectors.

12. The system as recited in claim 11 wherein each of the optical emitters of said first and second arrays comprises semiconductor lasers.

14. The system as recited in claim 11 wherein a subset of said plurality of lens elements comprise telecentric lenses having a bulk hologram recorded therein.

15. The system as recited in claim 11 wherein a subset of said plurality of lens elements comprise converging lenses having a bulk hologram recorded therein.

16. The system as recited in claim 11 further including a processor in data communication with said first and second expansion card slots over a bus with the optical emitters of said first and second arrays adapted to produce modulated optical energy in accordance with instructions received from said processor.

18. The system as recited in claim 17 wherein a subset of said plurality of lens elements comprise telecentric lenses.

19. The system as recited in claim 17 wherein a subset of said plurality of lens elements comprise converging lenses.

17. A backplane interconnect system comprising:

first and second expansion slots;

a first expansion card in electrical communication with said first expansion slot, said first expansion card having a first array of optical emitters to generate optical energy to propagate along a plurality of axes and a first array of optical receivers;

a second expansion card in electrical communication with said second expansion slot, said second expansion card having a second array of optical emitters to generate optical energy to propagate along a plurality of paths, and a second array of optical receivers, each of which is positioned to sense optical energy propagating along one of the plurality of optical axes, with the optical receivers of said first optical array positioned to sense optical energy propagating along said plurality of paths, with the optical emitters of said first and second arrays comprising semiconductor lasers and the optical receivers of said first and second array comprising charge injection devices; and

a holographic optical element including a plurality of lens elements, each of which has a bulk holographic transform function recorded throughout a volume thereof, defining a plurality of holographic transform functions, each of said plurality of detectors being associated with one of said plurality of holographic transform functions, with the holographic transform function associated with one of said plurality of detectors differing from the holographic transform functions associated with the remaining detector of said plurality of detectors.