Method and system for waveguide delay based equalization with summing at single-ended to differential converters in optical communication

• US 10,439,734 B2
• Filed: 06/28/2017
• Issued: 10/08/2019
• Est. Priority Date: 07/01/2016
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Luxtera Incorporated (Cisco Systems, Inc.)
• Inventors: Pang, Simon, Balardeta, Joseph
• Primary Examiner(s): Sandhu, Amritbir K
• Application Number:
  US15/636,540
• Publication Number:
  US 20180006732A1
• Time in Patent Office: 832 Days
• Field of Search: 398202-214
• CPC Class Codes: H04B 10/25891 Transmission components H04B10/40 takes precedence
• CPC Class Codes: H04B 10/691 Arrangements for optimizing the photodetector in the receiver
• CPC Class Codes: H04B 10/6931 Automatic gain control of the preamplifier

Abstract

Methods and systems for waveguide delay based equalization summing at single-ended to differential converters in optical communication are disclosed and may include: in an optoelectronic receiver including a directional coupler, photodetectors, transimpedance amplifiers (TIAs), and a gain stage, receiving an input optical signal; splitting the input optical signal into first and second optical signals using the directional coupler; generating a first current from the first optical signal using a first photodetector; generating a first voltage from the first current using a first TIA; communicating the first voltage to a first input of the gain stage; generating a second current from the second optical signal using a second photodetector; generating a second voltage from the first signal using a second TIA; communicating the second voltage to a second input of the gain stage; and generating a differential output voltage from the first and second voltages using the gain stage.

Claims

1. A method for communication, the method comprising:

in an optoelectronic receiver comprising a directional coupler, first and second photodetectors, first and second transimpedance amplifiers (TIAs), and a gain stage;

receiving an input optical signal;

splitting the input optical signal into first and second optical signals using the directional coupler;

delaying the first optical signal received from the directional coupler using an optical delay at an output of the directional coupler;

generating a first electrical current from the first optical signal using the first photodetector;

generating a first voltage from the first electrical current using the first TIA;

communicating the first voltage to a first input of the gain stage;

generating a second electrical current from the second optical signal using the second photodetector;

generating a second voltage from the first electrical signal using the second TIA;

communicating the second voltage to a second input of the gain stage; and

generating a differential output voltage from the first and second voltages using the gain stage.

2. The method according to claim 1, comprising delaying the first optical signal using a waveguide delay.

3. The method according to claim 2, wherein the waveguide delay is coupled to an output of the directional coupler.

4. The method according to claim 1, wherein the first and second photodetectors comprise photodiodes.

5. The method according to claim 1, comprising splitting the second optical signal into third and fourth optical signals using a second directional coupler before generating the second electrical signal.

6. The method according to claim 5, comprising coupling the delayed fourth optical signal to a third photodetector and summing its output current with an output current from the second photodetector.

7. The method according to claim 1, comprising weighting the second optical signal by configuring a gain of the second TIA.

8. The method according to claim 1, comprising weighting the second optical signal by configuring a gain of the second TIA.

9. The method according to claim 1, comprising weighting the first and second optical signals by configuring a coupling coefficient of the directional coupler.

10. The method according to claim 1, wherein the optoelectronic receiver is on a silicon complementary-metal oxide semiconductor (CMOS) photonics die.

11. A system for communication, the system comprising:

an optoelectronic receiver comprising a directional coupler, first and second photodetectors, first and second transimpedance amplifiers (TIAs), and a gain stage, the optoelectronic receiver being operable to;

receive an input optical signal;

split the input optical signal into first and second optical signals using the directional coupler;

delay the first optical signal received from the directional coupler using an optical delay at an output of the directional coupler;

generate a first electrical current from the first optical signal using the first photodetector;

generate a first voltage from the first electrical current using the first TIA;

communicate the first voltage to a first input of the gain stage;

generate a second electrical current from the second optical signal using the second photodetector;

generate a second voltage from the first electrical signal using the second TIA;

communicate the second voltage to a second input of the gain stage; and

generate a differential output voltage from the first and second voltages using the gain stage.

12. The system according to claim 11, wherein the optoelectronic receiver is operable to delay the first optical signal using a waveguide delay.

13. The system according to claim 12, wherein the waveguide delay is coupled to an output of the directional coupler.

14. The system according to claim 11, wherein the first and second photodetectors comprise photodiodes.

15. The system according to claim 11, wherein the optoelectronic receiver is operable to split the second optical signal into third and fourth optical signals using a second directional coupler before generating the second electrical signal.

16. The system according to claim 15, wherein the optoelectronic receiver is operable to couple the delayed fourth optical signal to a third photodetector and summing its output current with an output current from the second photodetector.

17. The system according to claim 11, wherein the optoelectronic receiver is operable to weight the first optical signal by configuring a gain of the first TIA.

18. The system according to claim 11, wherein the optoelectronic receiver is operable to weight the second optical signal by configuring a gain of the second TIA.

19. The system according to claim 11, wherein the optoelectronic receiver is operable to weight the first and second optical signals by configuring a coupling coefficient of the directional coupler.

20. A system for communication, the system comprising:

an optoelectronic receiver in a complementary metal-oxide semiconductor (CMOS) die, said optoelectronic receiver comprising a directional coupler, first and second photodetectors, first and second transimpedance amplifiers (TIAs), and a gain stage, the optoelectronic receiver being operable to;

receive an input optical signal;

split the input optical signal into first and second optical signals using the directional coupler;

delay the first optical signal using an optical delay at an output of the directional coupler;

generate a first electrical current from the delayed first optical signal using the first photodetector;

generate a first voltage from the first electrical current using the first TIA;

communicate the first voltage to a first input of the gain stage;

generate a second electrical current from the second optical signal using the second photodetector;

generate a second voltage from the first electrical signal using the second TIA;

communicate the second voltage to a second input of the gain stage; and

generate a differential output voltage from the first and second voltages using the gain stage.