Intensity-modulated direct detection with multi-channel multi-beaming

• US 10,355,780 B2
• Filed: 11/30/2017
• Issued: 07/16/2019
• Est. Priority Date: 12/30/2015
• Status: Active Grant

• Current Assignee: Meta Platforms, Inc. (f/k/a Facebook, Inc.)
• Original Assignee: Meta Platforms, Inc. (f/k/a Facebook, Inc.)
• Inventors: Wang, Shih-Cheng
• Primary Examiner(s): Kretzer, Casey L
• Application Number:
  US15/828,338
• Publication Number:
  US 20180102844A1
• Time in Patent Office: 593 Days
• CPC Class Codes: H04B 10/112 Line-of-sight transmission over an extended range
• CPC Class Codes: H04B 10/1121 One-way transmission
• CPC Class Codes: H04B 10/1129 Arrangements for outdoor wireless networking of information
• CPC Class Codes: H04B 10/501 Structural aspects
• CPC Class Codes: H04B 10/66 Non-coherent receivers, e.g. using direct detection
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04L 1/00 Arrangements for detecting or preventing errors in the information received correcting synchronisation H04L7/00
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 7/0331 with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock H04L7/0337 takes precedence

Abstract

Optical communication systems and methods using coherently combined optical beams are disclosed. A representative system includes a first data source for sending first data at a first frequency of a first optical beam to a first aperture, and at a second frequency of a second optical beam to a second aperture. The system further includes a second data source for sending second data at a third frequency of a third optical beam to the first aperture, and at a fourth frequency of a fourth optical beam to the second aperture. The system also includes a first interleaver of the first aperture configured to interleave the first data at the first frequency and the second data at the third frequency; and a second interleaver of the second aperture configured to interleave the first data at the second frequency and the second data at fourth frequency.

Claims

1. An optical transmitter, comprising:

a first aperture;

a second aperture;

a first data source configured to;

send a first optical beam at a first value of a property to the first aperture, the first optical beam comprising first data; and

send a second optical beam at a second value of the property to the second aperture, the second optical beam comprising the same first data;

a second data source configured to;

send a third optical beam at a third value of the property to the first aperture, the third optical beam comprising second data; and

send a fourth optical beam at a fourth value of the property to the second aperture, the fourth optical beam comprising the same second data;

a first interleaver of the first aperture configured to combine the first optical beam at the first value and the third optical beam at the third value into a first combined optical beam to be sent from the first aperture; and

a second interleaver of the second aperture configured to interleave the second optical beam at the second value and the fourth optical beam at the fourth value into a second combined optical beam to be sent from the second aperture.

2. The optical transmitter of claim 1, wherein timing inaccuracies between the first data and the second data arriving at the first aperture and the second aperture are adjusted by at least one first-in-first-out (FIFO) element or at least one phase-locked-loop (PLL).

3. The optical transmitter of claim 2, wherein the at least one FIFO element or the at least one PLL are connected to a common clock.

4. The optical transmitter of claim 2, wherein the property of a respective optical beam includes at least one of:

a frequency, a wavelength, a phase, or a polarization angle.

5. The optical transmitter of claim 2, wherein the at least one FIFO element is configured to perform a coarse adjustment of at least one optical beam included in the first optical beam, the second optical beam, the third optical beam, or the fourth optical beam.

6. The optical transmitter of claim 2, wherein the at least one PLL is configured to perform a fine adjustment of at least one optical beam included in the first optical beam, the second optical beam, the third optical beam, or the fourth optical beam.

7. The optical transmitter of claim 6, wherein the fine adjustment of the at least one optical beam includes independent adjustment of a phase of the at least one optical beam.

8. The optical transmitter of claim 1, wherein a combination of a fine adjustment of at least one optical beam and a coarse adjustment of the at least one optical beam improves a signal-to-noise ratio of the at least one optical beam, wherein the at least one optical beam is included in the first optical beam, the second optical beam, the third optical beam, or the fourth optical beam.

9. The optical transmitter of claim 1, wherein the property corresponds to a frequency, wherein the first value, the second value, the third value, and the fourth value are successively spaced apart by a constant offset.

10. The optical transmitter of claim 1, wherein the first aperture and the second aperture are spatially separated enough to cause the first combined optical beam and the second combined optical beam to experience statistically uncorrelated fading.

11. An optical receiver comprising:

a receive aperture to receive a first combined optical beam from a transmitter, wherein;

the first combined optical beam includes a second combined optical beam, a third combined optical beam, a fourth combined optical beam, and a fifth combined optical beam;

the second combined optical beam includes multiple optical beams each comprising same first data and having different values of a property;

the third combined optical beam includes multiple optical beams each comprising same second data and having different values of the property;

the fourth combined optical beam includes multiple optical beams each comprising same third data and having different values of the property;

the fifth combined optical beam includes multiple optical beams each comprising same fourth data and having different values of the property; and

a multi-stage deinterleaver configured to deinterleave the first combined optical beam into the second combined optical beam, the third combined optical beam, the fourth combined optical beam, and the fifth combined optical beam, the multi-stage deinterleaver comprising;

a first deinterleaver configured to;

receive the first combined optical beam from the receive aperture; and

deinterleave the first combined optical beam into a sixth combined optical beam and a seventh combined optical beam, wherein;

the sixth combined optical beam includes the second combined optical beam and the third combined optical beam; and

the seventh combined optical beam includes the fourth combined optical beam and the fifth combined optical beam;

a second deinterleaver configured to;

receive the sixth combined optical beam from the first deinterleaver;

deinterleave the sixth combined optical beam into the second combined optical beam and the third combined optical beam;

send the second combined optical beam to a first data sink; and

send the third combined optical beam to a second data sink; and

a third deinterleaver configured to;

receive the seventh combined optical beam from the first deinterleaver;

deinterleave the seventh combined optical beam into the fourth combined optical beam and the fifth combined optical beam;

send the fourth combined optical beam to a third data sink; and

send the fifth combined optical beam to a fourth data sink.

12. The optical receiver of claim 11, wherein the second combined optical beam, the third combined optical beam, the fourth combined optical beam, and the fifth combined optical beam are combined using dense wavelength division multiplexing (DWDM).

13. The optical receiver of claim 11, wherein the first data sink comprises:

an optical to electrical conversion unit;

an analog to digital conversion (ADC) unit; and

a digital equalizer.

14. The optical receiver of claim 11, wherein the receive aperture is a first receive aperture, wherein a portion of the first combined optical beam is received at the first receive aperture, further comprising:

a second receive aperture to receive a remaining portion of the first combined optical beam.

15. The optical receiver of claim 11, wherein frequencies associated with the second combined optical beam, the third combined optical beam, the fourth combined optical beam, and the fifth combined optical beam in the first combined optical beam identically match or approximately match transmitted frequencies of the second combined optical beam, the third combined optical beam, the fourth combined optical beam, and the fifth combined optical beam.

16. An optical communication system, comprising:

an optical transmitter comprising;

a first data source configured to send first data—

at a first frequency of a first optical beam to a first aperture, and

at a second frequency of a second optical beam to a second aperture;

a second data source configured to send second data—

at a third frequency of a third optical beam to the first aperture, and

at a fourth frequency of a fourth optical beam to the second aperture;

a first interleaver of the first aperture configured to interleave the first data at the first frequency and the second data at the third frequency;

a second interleaver of the second aperture configured to interleave the first data at the second frequency and the second data at the fourth frequency; and

wherein timing inaccuracies between the first data and the second data arriving at the first aperture and the second aperture are adjusted by at least one first-in-first-out (FIFO) element or at least one phaselocked-loop (PLL).

17. The optical communication system of claim 16, wherein the at least one FIFO element or the at least one PLL are connected to a common clock.

18. The optical communication system of claim 16, wherein the at least one FIFO element is configured to perform a coarse adjustment of at least one optical beam included in the first optical beam, the second optical beam, the third optical beam, or the fourth optical beam.

19. The optical communication system of claim 16, wherein the at least one PLL is configured to perform a fine adjustment of at least one optical beam included in the first optical beam, the second optical beam, the third optical beam, or the fourth optical beam.

20. The optical communication system of claim 19, wherein the fine adjustment of the at least one optical beam includes independent adjustment of a phase of the at least one optical beam.

21. The optical communication system of claim 16, wherein a combination of a fine adjustment of at least one optical beam and a coarse adjustment of the at least one optical beam improves a signal-to-noise ratio of the at least one optical beam, wherein the at least one optical beam is included in the first optical beam, the second optical beam, the third optical beam, or the fourth optical beam.