Granted Patent B2

US 12,598,002 · App. 18/478,417 · Granted Apr 7, 2026

Inventors: Ricardo Saad (San Jose, CA); Chiachen Chang (Saratoga, CA)

Assignee: Lumentum Technology UK Limited

H04B10/5057H04B10/564

Abstract

Claims (69)

1 . An optical transmitter, comprising:

an optical source configured to output an optical signal that is to be modulated with a primary data signal and a secondary data signal,

wherein a data rate of the primary data signal is greater than a data rate of the secondary data signal;

a semiconductor optical amplifier configured to modulate the optical signal with the secondary data signal;

an optical modulator configured to modulate the optical signal with the primary data signal;

a photodetector configured to generate a feedback signal based on the optical signal modulated with at least the secondary data signal; and

a controller configured to:

output the secondary data signal to the semiconductor optical amplifier,

wherein the secondary data signal has a modulation amplitude to control a modulation of the optical signal by the semiconductor optical amplifier;

obtain the feedback signal based on outputting the secondary data signal to the semiconductor optical amplifier;

determine, based on the feedback signal, an actual modulation index of the optical signal modulated with at least the secondary data signal; and

adjust the modulation amplitude of the secondary data signal based on a difference between the actual modulation index and a target modulation index.

2 . The optical transmitter of claim 1 , wherein the controller, to determine the actual modulation index, is configured to:

obtain a plurality of samples of the feedback signal,

wherein the plurality of samples include a plurality of high level samples and a plurality of low level samples;

determine a high level value based on the plurality of high level samples and a low level value based on the plurality of low level samples; and

determine the actual modulation index based on the high level value and the low level value.

3 . The optical transmitter of claim 2 , wherein the controller, to determine the high level value and the low level value, is configured to:

determine an average high level value of the plurality of high level samples and an average low level value of the plurality of low level samples; and

convert the average high level value to a first optical power value and the average low level value to a second optical power value,

wherein the high level value is the first optical power value, and the low level value is the second optical power value.

4 . The optical transmitter of claim 1 , wherein the photodetector is optically coupled to an output of the optical modulator.

5 . The optical transmitter of claim 1 , wherein the photodetector is optically coupled to an output of the semiconductor optical amplifier.

6 . The optical transmitter of claim 1 , further comprising:

a filter configured to filter the feedback signal,

wherein the photodetector is configured to output the feedback signal to the filter.

7 . The optical transmitter of claim 1 , wherein the optical modulator includes a Mach-Zehnder modulator.

8 . An optical transmitter, comprising:

a transmitter device configured to modulate an optical signal with a data signal; and

a controller configured to:

output the data signal to the transmitter device,

wherein the data signal has a modulation amplitude to control a modulation of the optical signal by the transmitter device;

obtain a feedback signal based on outputting the data signal to the transmitter device;

determine, based on the feedback signal, an actual modulation index of the optical signal modulated with the data signal; and

adjust the modulation amplitude of the data signal based on a difference between the actual modulation index and a target modulation index.

9 . The optical transmitter of claim 8 , wherein the transmitter device comprises:

a semiconductor optical amplifier configured to modulate the optical signal with the data signal.

10 . The optical transmitter of claim 8 , further comprising:

a photodetector configured to generate the feedback signal based on the optical signal modulated with the data signal.

11 . The optical transmitter of claim 10 , further comprising:

a filter configured to filter the feedback signal,

wherein the photodetector is configured to output the feedback signal to the filter.

12 . The optical transmitter of claim 8 , wherein the controller comprises an analog-to-digital converter configured to sample the feedback signal.

13 . The optical transmitter of claim 8 , wherein the controller comprises a digital-to-analog converter configured to output the data signal.

14 . The optical transmitter of claim 8 , wherein the controller, to determine the actual modulation index, is configured to:

obtain a plurality of samples of the feedback signal,

wherein the plurality of samples include a plurality of high level samples and a plurality of low level samples;

determine a high level value based on the plurality of high level samples and a low level value based on the plurality of low level samples; and

determine the actual modulation index based on the high level value and the low level value.

15 . A method, comprising:

outputting, by a controller, a low-speed data signal to a transmitter device,

wherein the low-speed data signal has a modulation amplitude to control a modulation of an optical signal by the transmitter device,

wherein the optical signal is to be modulated with a high-speed data signal and the low-speed data signal, and

wherein the low-speed data signal indicates diagnostic information, associated with a controlled network node of an optical network, and for a controlling network node of the optical network;

obtaining, by the controller and based on outputting the low-speed data signal to the transmitter device, a feedback signal generated by a photodetector based on the optical signal modulated with at least the low-speed data signal;

determining, by the controller and based on the feedback signal, an actual modulation index of the optical signal modulated with at least the low-speed data signal; and

adjusting, by the controller, the modulation amplitude of the low-speed data signal based on a difference between the actual modulation index and a target modulation index.

16 . The method of claim 15 , wherein the low-speed data signal is based on Manchester encoding.

17 . The method of claim 15 , wherein a data rate of the low-speed data signal is less than or equal to 10 kilobits per second, and a data rate of the high-speed data signal is greater than or equal to 1 gigabit per second.

18 . The method of claim 15 , wherein determining the actual modulation index of the optical signal comprises:

obtaining a plurality of samples of the feedback signal,

wherein the plurality of samples include a plurality of high level samples and a plurality of low level samples;

determining a high level value based on the plurality of high level samples and a low level value based on the plurality of low level samples; and

determining the actual modulation index based on the high level value and the low level value.

19 . The method of claim 18 , wherein determining the high level value and the low level value comprises:

determining an average high level value of the plurality of high level samples and an average low level value of the plurality of low level samples; and

converting the average high level value to a first optical power value and the average low level value to a second optical power value,

wherein the high level value is the first optical power value, and the low level value is the second optical power value.

20 . The method of claim 15 , wherein the target modulation index is in a range from 3% to 10%.

Assignments (2)

Continuity (2)

References Cited (15)