DEVICES AND TECHNIQUES FOR INTEGRATED OPTICAL DATA COMMUNICATION

• US 20150311982A1
• Filed: 03/15/2013
• Published: 10/29/2015
• Est. Priority Date: 11/29/2012
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Stojanovic, Vladimir Marko, Georgas, Michael Stephen, Orcutt, Jason Scott
• Granted Patent: US 9,768,881 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 10/25891 Transmission components H04B10/40 takes precedence
• CPC Class Codes: H04B 10/60 Receivers
• CPC Class Codes: H04B 10/697 Arrangements for reducing noise and distortion

Abstract

Devices and techniques for integrated optical data communication. An optical receiver may include a photodetector and a differential amplifier. The photodetector is coupled to an optical waveguide. The optical waveguide is configured to provide an optical signal encoding data. A first terminal of the differential amplifier is coupled to receive a photodetection signal from the photodetector. A second terminal of the differential amplifier is coupled to receive, from a noise measurement unit, a reference signal representing a noise component of the photodetection signal. The differential amplifier is configured to provide an amplifier signal encoding at least some of the data.

Claims

1. An optical receiver, comprising:

a photodetector coupled to an optical waveguide, the optical waveguide being configured to provide an optical signal encoding data; and

a differential amplifier with a first terminal and a second terminal, the first terminal being coupled to receive a photodetection signal from the photodetector, the second terminal being coupled to receive, from a noise measurement unit, a reference signal representing a noise component of the photodetection signal,

wherein the differential amplifier is configured to provide an amplifier signal encoding at least some of the data.

2. The optical receiver of claim 1, wherein the photodetector is a first photodetector, wherein the differential amplifier is a first differential amplifier, wherein the photodetection signal is a first photodetection signal, and wherein the optical receiver further comprises:

a second photodetector coupled to the optical waveguide, and

a second differential amplifier coupled to receive a second photodetection signal from the second photodetector,

wherein the optical receiver is configured to provide an electrical data signal encoding the data based, at least in part, on the first photodetection signal, the second photodetection signal, and the reference signal.

3. The optical receiver of claim 2, wherein the amplifier signal is a first amplifier signal, wherein the second differential amplifier is configured to provide a second amplifier signal encoding at least some of the data, and wherein:

the electrical data signal includes at least a portion of the first amplifier signal and at least a portion of the second amplifier signal, and

a data rate of the electrical data signal is approximately a sum of data rates of the first amplifier signal and the second amplifier signal.

4. The optical receiver of claim 2, wherein:

when a most recently encoded bit in the electrical data signal has a first bit value, a next bit to be encoded in the electrical data signal is provided by the first differential amplifier, and

when the most recently encoded bit in the electrical data signal has a second bit value, the next bit to be encoded in the electrical data signal is provided by the second differential amplifier.

5. The optical receiver of claim 2, wherein the first differential amplifier and the second differential amplifier are configured to perform decision-feedback equalization.

6. The optical receiver of claim 1, wherein the photodetector is a first photodetector, wherein the differential amplifier is a first differential amplifier, wherein the photodetection signal is a first photodetection signal, wherein the optical waveguide is a first optical waveguide, wherein the optical signal is a first optical signal, and wherein

the optical receiver further comprises:

a second photodetector coupled to a second optical waveguide, the second optical waveguide being configured to provide a second optical signal encoding the data, and

a second differential amplifier coupled to receive a second photodetection signal from the second photodetector, and

the optical receiver is configured to provide an electrical data signal encoding the data based, at least in part, on the first photodetection signal, the reference signal, and the second photodetection signal.

7. The optical receiver of claim 6, wherein the amplifier signal is a first amplifier signal, wherein the second differential amplifier is configured to provide a second amplifier signal encoding at least some of the data, and wherein:

the electrical data signal includes at least a portion of the first amplifier signal and at least a portion of the second amplifier signal, and

a data rate of the electrical data signal is approximately a sum of data rates of the first amplifier signal and the second amplifier signal.

8. The optical receiver of claim 6, wherein:

when a most recently encoded bit in the electrical data signal has a first bit value, a next bit to be encoded in the electrical data signal is provided by the first differential amplifier, and

when the most recently encoded bit in the electrical data signal has a second bit value, the next bit to be encoded in the electrical data signal is provided by the second differential amplifier.

9. The optical receiver of claim 6, wherein the first differential amplifier and the second differential amplifier are configured to perform decision-feedback equalization.

10. The optical receiver of claim 1, wherein the photodetector is a first photodetector, and wherein:

the optical receiver further comprises the noise measurement unit,

the noise measurement unit includes a second photodetector, and

the second photodetector provides the reference signal.

11. The optical receiver of claim 10, wherein the noise component of the photodetection signal is approximately equal to the reference signal.

12. The optical receiver of claim 1, wherein the differential amplifier is an integrating, clocked differential amplifier.

13. The optical receiver of claim 1, wherein the photodetector, the optical waveguide, and the differential amplifier are monolithically integrated on a semiconductor substrate.

14. A device comprising:

the optical receiver of claim 1;

the optical waveguide to which the photodetector of the optical receiver is coupled; and

an optical modulator coupled to the optical waveguide.

15. The device of claim 14, wherein the optical waveguide, the optical modulator, and the optical receiver are monolithically integrated on a semiconductor substrate.

16. The device of claim 1, wherein a threshold level of the differential amplifier is adjustable.

17. A method comprising:

converting at least a portion of an optical signal to an electrical signal;

determining a difference between the electrical signal and a reference signal representing a noise component of the electrical signal;

comparing the difference to one or more threshold levels; and

providing at least a portion of a data signal based on a result of comparing the difference to the one or more threshold levels.

18. The method of claim 17, wherein providing the data signal comprises:

in a case where the difference is greater than a first of the one or more threshold levels, encoding a first bit value in the data signal; and

in a case where the difference is less than the first threshold level, encoding a second bit value in the data signal.

19. The method of claim 17, wherein the portion of the optical signal is a first portion of the optical signal, the electrical signal is a first electrical signal, the difference is a first difference, the reference signal is a first reference signal, the portion of the data signal is a first portion of the data signal, and wherein:

determining the first difference, comparing the first difference, and providing at least the first portion of the data signal are performed with a first differential amplifier, and

the method further comprises;

converting at least a second portion of the optical signal to a second electrical signal,

with a second differential amplifier, determining a second difference between the second electrical signal and a second reference signal representing a noise component of the second electrical signal,

with the second differential amplifier, comparing the second difference to the one or more threshold levels,

with the second differential amplifier, providing a second portion of the data signal based on a result of comparing the second difference to the one or more threshold levels.

20. The method of claim 19, wherein a data rate of the data signal is a sum of data rates of the first differential amplifier and the second differential amplifier.

21. The method of claim 17, wherein:

comparing the difference to one or more threshold levels includes comparing the difference to a first threshold level and to a second threshold level; and

providing the data signal comprises;

in a case where the difference is greater than the first and second threshold levels, encoding a first bit value in the data signal;

in a case where the difference is less than the first and second threshold levels, encoding a second bit value in the data signal;

in a case where the difference is between the first and second threshold levels, determining whether to encode the first bit value or the second bit value in the data signal based on a bit value most recently encoded in the data signal.

22. The method of claim 17, further comprising adjusting at least one of the one or more threshold levels.

23. An optical receiver, comprising:

a photodetection circuit coupled to an optical waveguide, the optical waveguide being configured to provide an optical signal; and

an amplification circuit, including;

a first amplifier configured to provide a first amplifier signal based on a first photodetection signal provided by the photodetection circuit, the first photodetection signal corresponding to a first portion of the optical signal, the first portion of the optical signal encoding a first bit, and

a second amplifier configured to provide a second amplifier signal based on a second photodetection signal provided by the photodetection circuit, the second photodetection signal corresponding to a second portion of the optical signal, the second portion of the optical signal encoding a second bit,

wherein the amplification circuit is configured to provide an electrical data signal encoding the first and second bits.

24. The optical receiver of claim 23, wherein:

the electrical data signal includes at least portions of the first and second amplifier signals,

a data rate of the electrical data signal is approximately a sum of data rates of the first and second amplifier signals.

25. The optical receiver of claim 23, wherein:

when the second bit has a first bit value, a next bit to be encoded in the electrical data signal is provided by the first amplifier, and

when the second bit has a second bit value, the next bit to be encoded in the electrical data signal is provided by the second amplifier.

26. The optical receiver of claim 23, wherein the first amplifier and the second amplifier are configured to perform decision-feedback equalization.

27. The optical receiver of claim 23, wherein the first amplifier is an integrating amplifier.

28. The optical receiver of claim 23, wherein the photodetection circuit, the optical waveguide, and the amplification circuit are monolithically integrated on a semiconductor substrate.

29. The optical receiver of claim 23, wherein the photodetection circuit includes a photodetector configured to convert the first portion of the optical signal into the first photodetection signal, and to convert the second portion of the optical signal into the second photodetection signal.

30. The optical receiver of claim 29, wherein the photodetector is a photodiode.

31. The optical receiver of claim 23, wherein the photodetection circuit includes:

a first photodetector configured to convert the first portion of the optical signal into the first photodetection signal, and

a second photodetector configured to convert the second portion of the optical signal into the second photodetection signal.

32. The optical receiver of claim 31, wherein the first and second photodetectors are coupled to the optical waveguide.

33. The optical receiver of claim 31, wherein:

the first photodetector is coupled to a first branch of the optical waveguide,

the second photodetector is coupled to a second branch of the optical waveguide, and

the first and second branches of the optical waveguide are configured to provide, respectively, the first and second portions of the optical signal.

34. The optical receiver of claim 31, wherein the first photodetector is a photodiode.

35. The optical receiver of claim 23, wherein the photodetection circuit is configured to convert the first portion of the optical signal into the first photodetection signal, and to convert the second portion of the optical signal into the second photodetection signal.

36. A method comprising:

obtaining a first electrical signal and a second electrical signal, the first electrical signal corresponding to a first portion of the optical signal, the second electrical signal corresponding to a second portion of the optical signal;

with a first amplifier, providing a first amplifier signal based on the first electrical signal, the first amplifier signal encoding a first bit;

with a second amplifier, providing a second amplifier signal based on the second electrical signal, the second amplifier signal encoding a second bit; and

providing a data signal including the first amplifier signal and/or the second amplifier signal.

37. The method of claim 36, wherein obtaining the first electrical signal comprises converting the first portion of the optical signal into the first electrical signal.

38. The method of claim 36, wherein:

providing the data signal comprises providing the data signal including the first and second amplifier signals, and

a data rate of the data signal is approximately a sum of data rates of the first and second amplifier signals.

39. The method of claim 36, wherein providing the data signal comprises:

in a case where a most recently encoded bit of the data signal has a first bit value, providing the data signal including the first amplifier signal, and

in a case where the most recently encoded bit of the data signal has a second bit value, providing the data signal including the second amplifier signal.

40. The method of claim 36, further comprising performing decision-feedback equalization with the first and second amplifiers.

41. The method of claim 36, wherein the first amplifier is a clocked amplifier.

42. The method of claim 36, wherein the photodetection circuit, the optical waveguide, and the first and second amplifiers are monolithically integrated on a semiconductor substrate.