Free-space, twisted light optical communication system

• US 10,581,522 B1
• Filed: 12/06/2018
• Issued: 03/03/2020
• Est. Priority Date: 12/06/2018
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Innes, Timothy, Russ, Keith
• Primary Examiner(s): Tran, Dzung D
• Application Number:
  US16/211,809
• Time in Patent Office: 453 Days
• CPC Class Codes: H04B 10/11 Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
• CPC Class Codes: H04B 10/1123 Bidirectional transmission
• CPC Class Codes: H04B 10/40 Transceivers

Abstract

Aspects of the subject disclosure may include, determining a twist number based on digital input data, wherein the twist number corresponds to a predetermined orbital angular momentum of a photon. An adjustment value is generated based on the twist number, and multiple orbital angular momentum modulators are adjusted, wherein the modulators are adapted to change orbital angular momenta of photons of an input optical beam according to the adjustment value. Application of a light beam to the multiple orbital angular momentum modulators applies orbital angular momenta to the input optical beam resulting in a modulated optical beam having a predetermined number of twists based on the predetermined orbital angular momentum. Other embodiments are disclosed.

Claims

1. A device, comprising:

a processing system including a processor; and

a memory that stores executable instructions that, when executed by the processing system, facilitate performance of operations, the operations comprising;

receiving digital input data;

determining a twist number based on the digital input data, wherein the twist number corresponds to a predetermined orbital angular momentum;

deriving an adjustment value based on the twist number; and

controlling a plurality of orbital angular momentum modulators adapted to change orbital angular momenta of an input, free-space optical beam according to the adjustment value,

wherein application of a free-space light beam to the plurality of orbital angular momentum modulators applies orbital angular momenta to the input, free-space optical beam resulting in a modulated free-space optical beam having a predetermined number of twists based on the predetermined orbital angular momentum.

2. The device of claim 1, wherein the plurality of orbital angular momentum modulators comprise spiral phase plates.

3. The device of claim 2, wherein the spiral phase plates are adjustable to apply a selectable value of orbital angular momentum.

4. The device of claim 1, wherein the operations further comprise:

receiving the modulated free-space optical beam to obtain a received, twisted free-space optical beam;

generating a first image based on the received, twisted free-space optical beam;

applying a threshold filter to the first image, wherein the threshold filter is adapted to determine a comparison of an optical angular momentum of the received, twisted free-space optical beam to a predetermined threshold number of twists; and

re-directing the received, twisted free-space optical beam according to the comparison of the optical angular momentum of the received, twisted free-space optical beam to the predetermined threshold number of twists, to obtain a re-directed received, twisted free-space optical beam.

5. The device of claim 4, wherein the operations further comprise:

determining a second image based on the re-directed received, twisted free-space optical beam; and

evaluating the second image to detect a number of twists of the re-directed received, twisted free-space optical beam, resulting in a detected number of twists, wherein the detected number of twists.

6. The device of claim 5, wherein the operations further comprise decoding the detected number of twists to determine the digital input data.

7. The device of claim 1, wherein the device is mounted proximal to a power line, the operations further comprising obtaining first electrical power from an electromagnetic field of the power line, wherein the device is adapted to operate using the first electrical power.

8. The device of claim 7, wherein the operations further comprise obtaining second electrical power from a local, renewable energy source, when available, wherein the device is adapted to operate using the second electrical power, the operations further comprising using the second electrical power, when available, exclusively.

9. A method, comprising:

obtaining, by a processing system including a processor, input data;

identifying, by the processing system, a twist number based on the input data, wherein the twist number corresponds to a predetermined orbital angular momentum;

determining, by the processing system, an adjustment value based on the twist number; and

controlling, by the processing system, a plurality of orbital angular momentum modulators adapted to change orbital angular momenta of an input optical beam according to the adjustment value,

wherein application of a light beam to the plurality of orbital angular momentum modulators applies orbital angular momenta to the input optical beam resulting in a modulated optical beam having a predetermined number of twists based on the predetermined orbital angular momentum.

10. The method of claim 9, further comprising:

receiving, by the processing system, the modulated optical beam to obtain a received optical beam;

obtaining, by the processing system, a first image based on the received optical beam;

applying, by the processing system, a threshold filter to the first image, wherein the threshold filter is adapted to determine a comparison of an optical angular momentum of the received optical beam to a predetermined threshold number of twists; and

controlling, by the processing system, an optical directing device to redirect the received optical beam according to the comparison of the optical angular momentum of the received optical beam to the predetermined threshold number of twists, to obtain a re-directed received, twisted optical beam.

11. The method of claim 10, further comprising:

determining, by the processing system, a second image based on the re-directed received, twisted optical beam; and

evaluating, by the processing system, the second image to detect a number of twists of the re-directed received, twisted optical beam, resulting in a detected number of twists, wherein the detected number of twists.

12. The method of claim 11, further comprising:

decoding, by the processing system, the detected number of twists to determine the input data.

13. The method of claim 11, wherein the evaluating of the second image further comprises utilizing, by the processing system, an image processing technique.

14. The method of claim 9, further comprising obtaining first electrical power from an electromagnetic field of a power line, wherein the processing system is mounted proximal to the power line, and wherein the processing system is adapted to operate using the first electrical power.

15. The method of claim 14, further comprising:

obtaining, by the processing system, second electrical power from a local, renewable energy source, when available,

wherein the processing system is adapted to operate using the second electrical power, and wherein the second electrical power, when available, is used exclusively.

16. A non-transitory, machine-readable medium, comprising executable instructions that, when executed by a processing system including a processor, facilitate performance of operations, the operations comprising:

determining a twist number based on digital input data, wherein the twist number corresponds to a predetermined orbital angular momentum of a photon;

generating an adjustment value based on the twist number; and

adjusting a plurality of orbital angular momentum modulators adapted to change orbital angular momenta of photons of an input optical beam according to the adjustment value,

wherein application of a light beam to the plurality of orbital angular momentum modulators applies orbital angular momenta to the input optical beam resulting in a modulated optical beam having a predetermined number of twists based on the predetermined orbital angular momentum.

17. The non-transitory, machine-readable medium of claim 16, wherein the operations further comprise:

generating a first image based on a received, twisted optical beam;

applying a threshold filter to the first image, wherein the threshold filter is adapted to determine a comparison of an optical angular momentum of the received, twisted optical beam to a predetermined threshold number of twists; and

adjusting an optical directing device to redirect the received, twisted optical beam according to the comparison of the optical angular momentum of the received, twisted optical beam to the predetermined threshold number of twists, to obtain a re-directed received, twisted optical beam.

18. The non-transitory, machine-readable medium of claim 17, wherein the operations further comprise:

determining a second image based on the re-directed received, twisted optical beam; and

processing the second image to detect a number of twists of the re-directed received, twisted optical beam, resulting in a detected number of twists, wherein the detected number of twists.

19. The non-transitory, machine-readable medium of claim 18, wherein the processing of the second image further comprises applying image processing to the second image.

20. The non-transitory, machine-readable medium of claim 16, wherein the operations further comprise:

obtaining first electrical power from an electromagnetic field of a power line, wherein the processing system is adapted to operate using the first electrical power.