Electrical crosstalk reduction in a high-order digital optical modulator

Patent metadata

Field	Value
Publication number	US-9746698-B2
Application number	US-201514832840-A
Country	US
Kind code	B2
Filing date	Aug 21, 2015
Priority date	Aug 21, 2015
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

A digital optical modulator including a waveguide comprising a plurality of light paths, and a plurality of phase shifter segments, each optically coupled to a light path from the plurality of light paths, configured to modulate light carried in the plurality of light paths to generate a modulated light in response to an electrical drive signal, at least two of the plurality of phase shifter segments having the same length. A digital optical modulator comprising a first waveguide arm comprising a first end and a second end, a first plurality of phase shifter segments with at least two of the first plurality of phase shifter segments that are the same length optically coupled to the waveguide arm, and a second waveguide arm optically coupled to the first waveguide arm at the first end and the second end.

First claim

What is claimed is:

1. A transmitter comprising:
an encoder configured to:
encode data to produce encoded data; and
output the encoded data;

an optical source configured to provide light;
a digital optical modulator coupled to the encoder and the optical source and comprising:
a first waveguide arm comprising a plurality of light paths; and
a plurality of phase shifter segments coupled to the light paths and configured to modulate the light using the encoded data to generate a modulated light, wherein the phase shifter segments comprise a first most significant bit (MSB) phase shifter segment configured to receive a first MSB digital electrical drive voltage and a first least significant bit (LSB) phase shifter segment configured to receive a first LSB digital electrical drive voltage, wherein each of the phase shifter segments corresponds with a bit of the encoded data, wherein each bit is associated with only one phase shifter segment in the first waveguide arm, and wherein lengths of the phase shifter segments are not in a binary relationship and the first LSB digital electrical drive voltage is smaller than the first MSB digital electrical drive voltage to reduce electrical crosstalk between the phase shifter segments; and

an electrical driver coupled to the digital optical modulator and configured to provide the first MSB digital electrical drive voltage and the first LSB digital electrical drive voltage.

2. The transmitter of claim 1 , wherein each of the phase shifter segments corresponds to a bit location in a digital electrical word, wherein the first MSB phase shifter segment corresponds with an MSB for the digital electrical word, and wherein the first LSB phase shifter segment corresponds with an LSB for the digital electrical word.

3. The transmitter of claim 2 , wherein the first MSB phase shifter segment is longer than the first LSB phase shifter segment.

4. The transmitter of claim 1 , wherein the modulated light carries digital information.

5. The transmitter of claim 1 , wherein the phase shifter segments are configured to create a binary relationship of phase change.

6. The transmitter of claim 1 , wherein the phase shifter segments comprise a plurality of MSB phase shifter segments and a plurality of LSB phase shifter segments, and wherein the LSB phase shifter segments are longer than a power-of-2 relationship compared to the MSB phase shifter segments.

7. A digital optical modulator comprising:
a first waveguide arm comprising a first end and a second end;
a first plurality of phase shifter segments coupled to the first waveguide arm and comprising a first most significant bit (MSB) phase shifter segment configured to receive a first MSB digital electrical drive voltage and a first least significant bit (LSB) Phase shifter segment configured to receive a first LSB digital electrical drive voltage, wherein each of the phase shifter segments corresponds with a bit, wherein each bit is associated with only one phase shifter segment in the first waveguide arm, and wherein lengths of the phase shifter segments are not in a binary relationship and the first LSB digital electrical drive voltage is smaller than the first MSB digital electrical drive voltage to reduce electrical crosstalk between the phase shifter segments; and
a second waveguide arm optically coupled to the first waveguide area at the first end and the second end.

8. The digital optical modulator of claim 7 , further comprising a plurality of electrical contacts coupled to the phase shifter segments, wherein at least two of the electrical contacts are configured to receive different digital electrical drive voltage levels.

9. The digital optical modulator of claim 8 , wherein the different digital electrical drive voltage levels use a power-of-two voltage reduction relationship.

10. The digital optical modulator of claim 7 , wherein the first plurality of phase shifter segments does not use a power-of-two length reduction relationship.

11. The digital optical modulator of claim 7 , wherein a first portion of the first plurality of phase shifter segments uses a power-of-two length reduction relationship, and wherein a second portion of the first plurality of phase shifter segments does not use a power-of-two length reduction.

12. The digital optical modulator of claim 7 , wherein the first waveguide arm is substantially parallel to the second waveguide arm.

13. The digital optical modulator of claim 7 , further comprising a second plurality of phase shifter segments electro-optically coupled to the second waveguide arm, and wherein at least two of the second plurality of phase shifter segments are the same length.

14. The digital optical modulator of claim 7 , wherein the phase shifter segments are configured to create a binary relationship of phase change.

15. A digital optical modulator comprising:
a first waveguide arm configured to receive a light at a first end and to output a modulated light at a second end; and
a first plurality of phase shifter segments, coupled to the first waveguide arm, comprising a first most significant bit (MSB) phase shifter segment and a first least significant bit (LSB) phase shifter segment, and configured to modulate the light based on digital electrical drive voltages to generate the modulated light,
wherein the first MSB phase shifter segment is configured to receive a first MSB digital electrical drive voltage,
wherein the first LSB phase shifter segment is configured to receive a first LSB digital electrical drive voltage,
wherein each of the phase shifter segments corresponds with a bit, wherein each bit is associated with only one phase shifter segment in the first waveguide arm, and
wherein lengths of the phase shifter segments are not in a binary relationship and the first LSB digital electrical drive voltage is smaller than the first MSB digital electrical drive voltage to reduce electrical crosstalk between the phase shifter segments.

16. The digital optical modulator of claim 15 , further comprising a plurality of electrodes coupled to the first plurality of phase shifter segments, wherein two or more of the electrodes are configured to receive different digital electrical drive voltage levels.

17. The digital optical modulator of claim 15 , wherein a portion of the first plurality of phase shifter segments uses a power-of-two length reduction relationship.

18. The digital optical modulator of claim 15 , further comprising a second waveguide arm optically coupled to the first waveguide arm at the first end and the second end.

19. The digital optical modulator of claim 18 , wherein the second waveguide arm is an idle arm.

20. The digital optical modulator of claim 18 , further comprising a second plurality of phase shifter segments electro-optically coupled to the second waveguide arm, and wherein at least two of the second plurality of phase shifter segments are the same length.

21. The digital optical modulator of claim 15 , wherein the phase shifter segments are configured to create a binary relationship of phase change.

Assignees

• Huawei Tech Co Ltd

Inventors

• Goodwill Dominic John

Classifications

• H04Q11/0005

  Switch and router aspects · CPC title

• G02F1/011 Primary

  in optical waveguides, not otherwise provided for in this subclass · CPC title

• G02F1/225 Primary

  in an optical waveguide structure · CPC title

• H04B10/541

  Digital intensity or amplitude modulation · CPC title

• H04B10/505

  using external modulation · CPC title