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

Patent metadata

Field	Value
Publication number	US-9866320-B2
Application number	US-201514984173-A
Country	US
Kind code	B2
Filing date	Dec 30, 2015
Priority date	Dec 30, 2015
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

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.

First claim

The invention claimed is:

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

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 element 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 FIFO elements.

6. The system of claim 5 , further comprising:
a first phase-locked-loop (PLL) connected to the first FIFO element;
a second PLL connected to the second FIFO element;
a third PLL connected to the third FIFO element; and
a fourth PLL connected to the fourth FIFO element,
wherein the PLLs are connected to a common data clock for synchronizing the FIFO elements.

7. The system of claim 1 , further comprising a deinterleaver configured to: receive the first data at the first and the second frequencies from the RX aperture, and to receive the second data at the third and the fourth frequencies from the RX aperture; send the first data at the first and the second frequencies to a first data sink; and send the second data at the third and the fourth frequencies to a second data sink.

8. The system of claim 2 , further comprising:
a receive (RX) aperture configured to receive the first data, the second data, the third data, and the fourth data;
a first deinterleaver configured to receive the first data, the second data, the third data, 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.

9. The system of claim 8 wherein the first data sink comprises:
an optical to electrical conversion unit;
an analog to digital conversion (ADC) unit; and
a digital equalizer.

10. 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 to generate second interleaved data;
sending the first interleaved data from the first aperture to a receive (RX) aperture using a first transmission beam; and
sending the second interleaved data from the second aperture to the RX aperture using a second transmission beam.

11. The method of claim 10 , 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 seco

Assignees

• Facebook Inc

Inventors

• Wang Shih-Cheng

Classifications

• H04J14/02

  Wavelength-division multiplex systems · CPC title

• H04L7/0331

  with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock (H04L7/0337 takes precedence) · CPC title

• H04B10/112 Primary

  Line-of-sight transmission over an extended range · CPC title

• H04B10/501

  Structural aspects · CPC title

• H04B10/66

  Non-coherent receivers, e.g. using direct detection · CPC title