INTENSITY-MODULATED DIRECT DETECTION WITH MULTI-CHANNEL MULTI-BEAMING

• US 20180102844A1
• Filed: 11/30/2017
• Published: 04/12/2018
• 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
• Granted Patent: US 10,355,780 B2
• Time in Patent Office: 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 data source configured to send first data—

at a first value of a property of a first optical beam to a first aperture, and

at a second value of the property of a second optical beam to a second aperture;

a second data source configured to send second data—

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

at a fourth value of the property 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 value and the second data at the third value; and

a second interleaver of the second aperture configured to interleave the first data at the second value and the second data at the fourth value.

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 1, 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 constant offset allows the first optical beam, the second optical beam, the third optical beam, or the fourth optical beam to experience to experience statistically uncorrelated fading.

11. An optical receiver comprising:

a receive aperture to receive a combined optical beam from a transmitter, wherein the combined optical beam includes a first optical beam, a second optical beam, a third optical beam, and a fourth optical beam; and

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

a first deinterleaver configured to receive the combined optical beam from the receive aperture;

a second deinterleaver configured to—

receive the first optical beam and the second optical beam from the multi-stage deinterleaver,

send the first optical beam to a first data sink, and

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

a third deinterleaver configured to—

receive the third optical beam and the fourth optical beam from the first deinterleaver,

send the third optical beam to a third data sink, and

send the second optical beam to a fourth data sink.

12. The optical receiver of claim 10, wherein the first optical beam, the second optical beam, the third optical beam, and the fourth optical beam are combined using dense wavelength division multiplexing (DWDM).

13. The optical receiver of claim 10, 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 combined optical beam is received at the first receive aperture, further comprising:

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

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