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

• US 20170195061A1
• Filed: 12/30/2015
• Published: 07/06/2017
• 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 9,866,320 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 communication system, 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; 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.

2. The system of claim 1 wherein:

the first data source is further configured to send the first data

at a fifth frequency of a fifth optical beam to a third aperture, and

at a sixth frequency of a sixth optical beam to a fourth aperture;

the second data source is further configured to send the second data

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

at an eighth frequency of an eighth optical beam to the fourth aperture;

the optical system further comprising;

a third data source configured to send third data

at a ninth frequency of a ninth optical beam to the first aperture,

at a tenth frequency of a tenth optical beam to the second aperture,

at an eleventh frequency of an eleventh optical beam to the third aperture, and

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

a fourth data source configured to send fourth data

at a thirteenth frequency of a thirteenth optical beam to the first aperture,

at a fourteenth frequency of a fourteenth optical beam to the second aperture,

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

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

a third interleaver of the third aperture configured to interleave the first data at the fifth frequency, the second data at the seventh frequency, the third data at the eleventh frequency, and the fourth data at the fifteenth frequency; and

a fourth interleaver of the fourth aperture configured to interleave the first data at the sixth frequency, the second data at the eighth frequency, the third data at the twelfth frequency, and the fourth data at the sixteenth frequency.

3. The system of claim 1 wherein adjacent frequencies of the optical beams are offset by a constant difference.

4. The system of claim 2, further comprising:

a first first-in-first-out (FIFO) element between the first data source and the first aperture;

a second FIFO element between the first data source and the second aperture;

a third FIFO element between the second data source and the first aperture; and

a fourth FIFO element between the second data source and the second aperture,

wherein each FIFO is configured to output received data in order of receiving the received data.

5. The system of claim 4, further comprising a common data clock for synchronizing the FIFOs.

6. The system of claim 5, further comprising:

a first phase-locked-loop (PLL) connected to the first FIFO;

a second PLL connected to the second FIFO;

a third PLL connected to the third FIFO; and

a fourth PLL connected to the fourth FIFO,

wherein the PLLs are connected to the common data clock for synchronizing the FIFOs.

7. The system of claim 1, further comprising a receive (RX) aperture configured to receive the first data at the first and second frequencies, and the second data at the third and fourth frequencies.

8. The system of claim 7, further comprising a deinterleaver configured to:

receive the first data at the first and second frequencies from the RX aperture, and to receive the second data at the third and fourth frequencies from the RX aperture;

send the first data at the first and second frequencies to a first data sink; and

send the second data at the third and fourth frequencies to a second data sink.

9. The system of claim 2, further comprising:

a receive (RX) aperture configured to receive the first, the second, the third and the fourth data;

a first deinterleaver configured to receive the first, the second, the third and the fourth data from the RX aperture;

a second deinterleaver configured to

receive the first data and the second data from the first deinterleaver,

send the first data to a first data sink, and

send the second data to a second data sink; and

a third deinterleaver configured to

receive the third data and the fourth data from the first deinterleaver,

send the third data to a third data sink, and

send the second data to a fourth data sink.

10. The system of claim 9 wherein the first data sink comprises:

an optical to electrical conversion unit;

an analog to digital conversion (ADC) unit; and

a digital equalizer.

11. A method for optical communication, comprising:

sending first data from a first data source

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

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

sending second data from a second data source

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

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

interleaving the first data at the first frequency of the first optical beam with the second data at the third frequency of the third optical beam using a first interleaver of the first aperture to generate first interleaved data;

interleaving the first data at the second frequency of the second optical beam with the second data at the fourth frequency of the fourth optical beam using a second interleaver of the second aperture;

sending first interleaved data from the first aperture to a receiver (RX) aperture using a first transmission beam; and

sending second interleaved data from the second aperture to the RX aperture using a second transmission beam.

12. The method of claim 11, further comprising:

sending the first data from the first data source

to a third aperture at a fifth frequency of a fifth optical beam, and

to a fourth aperture at a sixth frequency of a sixth optical beam;

sending the second data from the second data source

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

to the fourth aperture at an eighth frequency of an eighth optical beam;

sending third data from a third data source

to the first aperture at a ninth frequency of a ninth optical beam,

to the second aperture at a tenth frequency of a tenth optical beam,

to the third aperture at an eleventh frequency of an eleventh optical beam, and

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

sending fourth data from a fourth data source

to the first aperture at a thirteenth frequency of a thirteenth optical beam,

to the second aperture at a fourteenth frequency of a fourteenth optical beam,

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

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

using the first interleaver of the first aperture, interleaving the third data at the ninth frequency of the ninth optical beam with the fourth data at the thirteenth frequency of the thirteenth optical beam;

using the second interleaver of the second aperture, interleaving the third data at the tenth frequency of the tenth optical beam with the second data at the fourteenth frequency of the fourteenth optical beam;

using a third interleaver of the third aperture, interleaving the first data at the fifth frequency of the first optical beam, the second data at the seventh frequency of the seventh optical beam, the third data at the eleventh frequency of the eleventh optical beam, and the fourth data at the fifteenth frequency of the fifteenth optical beam; and

using a fourth interleaver of the fourth aperture, interleaving the first data at the sixth frequency of the sixth optical beam, the second data at the eighth frequency of the eighth optical beam, the third data at the twelfth frequency of the twelfth optical beam, and the fourth data at the sixteenth frequency of the sixteenth optical beam; and

sending interleaved data to the RX using the first transmission beam for the first aperture, the second transmission beam for the second aperture, a third transmission beam for the third aperture, and a fourth transmission beam for the fourth aperture.

13. The method of claim 12 wherein adjacent frequencies of the optical beams are offset by a constant difference.

14. The method of claim 13 wherein the constant difference is a first constant difference, and wherein adjacent frequencies of the transmission beams are offset by a second constant difference.

15. The method of claim 11, further comprising:

receiving the first data at the first frequency of the first optical beam by a first first-in-first-out (FIFO) element;

receiving the second data at the third frequency of the third optical beam by a second FIFO element;

synchronizing the first and the second FIFO elements using a common data clock.

16. The method of claim 12, further comprising:

receiving the first data at the first frequency of the first optical beam by a first first-in-first-out (FIFO) element;

receiving the second data at the third frequency of the third optical beam by a second FIFO element;

receiving the third data at the ninth frequency of the ninth optical beam by a third FIFO element;

receiving the fourth data at the thirteenth frequency of the thirteenth optical beam by a fourth FIFO element;

synchronizing the first, the second, and the fourth FIFO elements using a common data clock.

17. The method of claim 16, further comprising:

synchronizing the first FIFO using a first phase-locked-loop (PLL) connected to the common data clock;

synchronizing the second FIFO using a second PLL connected to the common data clock;

synchronizing the third FIFO using a third PLL connected to the common data clock; and

synchronizing the fourth FIFO using a fourth PLL connected to the common data clock.

18. The method of claim 11, further comprising receiving the first data at the first and second frequencies, and the second data at the third and fourth frequencies by a receive (RX) aperture.

19. The method of claim 18, further comprising:

receiving the first data and the second data by a deinterleaver from the RX aperture;

deinterleaving the first data and the second data;

sending the first data at the first and second frequencies to a first data sink; and

sending the second data at the third and fourth frequencies to a second data sink.

20. The method of claim 9 further comprising:

converting the first data and the second data from optical to analog electrical signals;

converting the analog electrical signals to digital electrical signals; and

equalizing the digital electrical signals.