Mach-Zehnder interferometer device for wavelength locking

Patent metadata

Field	Value
Publication number	US-12399412-B2
Application number	US-202318526269-A
Country	US
Kind code	B2
Filing date	Dec 1, 2023
Priority date	Sep 9, 2019
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

Disclosed herein is an integrated photonics device including an on-chip wavelength stability monitor. The wavelength stability monitor may include one or more interferometric components, such as Mach-Zehnder interferometers and can be configured to select among the output signals from the interferometric components for monitoring the wavelength emitted by a corresponding photonic component, such as a light source. The selection may be based on a slope of the output signal and in some examples may correspond to a working zone at or around a wavelength or wavelength range. In some examples, the interferometric components can be configured with different phase differences such that the corresponding working zones have different wavelengths. In some examples, the slopes of the output signals may be weighted based on the steepness of the slope and all of the output signals may include information for wavelength locking the measured wavelength to the target wavelength.

First claim

The invention claimed is:

1. A system comprising:
a pair of light sources configured to emit light;
a splitter configured to receive the light emitted by the pair of light source and split the light between a first output light path and a second output light path;
a wavelength monitor configured to receive incoming light along the second output light path and generate a plurality of output signals; and
a controller configured to determine a power weighted average wavelength of the light emitted by the pair of light sources using the plurality of output signals, wherein:
the wavelength monitor comprises:
a set of splitters configured to split the incoming light into a first portion of the incoming light, a second portion of the incoming light, and a third portion of the incoming light;
a first Mach-Zehnder interferometer (MZI) configured to receive the first portion of the incoming light and generate a first output signal of the plurality of output signals;
a second MZI configured to receive the second portion of the incoming light and generate a second output signal of the plurality of output signals; and
a third MZI configured to receive the third portion of the incoming light and generate a third output signal of the plurality of output signals.

2. The system of claim 1 , wherein:
the pair of light sources comprises a first light source that is operable to emit a first wavelength of light and a second light source that is operable to emit a second wavelength of light; and
the controller is configured to shift at least one of the first wavelength or the second wavelength using the determined power weighted average wavelength.

3. The system of claim 1 , wherein:
the splitter splits the light emitted by the pair of light sources asymmetrically between the first output light path and the second output light path.

4. The system of claim 1 , wherein:
each of the plurality of outputs signals has a sinusoidal relationship between wavelength and intensity and a corresponding phase; and
the corresponding phases of the plurality of output signals are different.

5. The system of claim 1 , wherein the set of splitters comprises:
a first splitter configured to split the incoming light between a first light path and a second light path;
a second splitter configured to split light received along the first light path between a third light path and a fourth light path; and
a third splitter configured to split light received along the second light path between a fifth light path and a sixth light path, wherein:
the first MZI receives the first portion of the incoming light beam along the third light path;
the second MZI receives the second portion of the incoming light beam along the fourth light path; and
the third MZI receives the third portion of the incoming light beam along the fifth light path.

6. The system of claim 5 , wherein the wavelength monitor comprises a power monitor configured to measure an intensity of a fourth portion of the input light received along the sixth light path.

7. The system of claim 1 , wherein the wavelength monitor comprises a plurality of photodetectors configured to measure the plurality of output signals.

8. A method comprising:
generating a first wavelength of light with a first light source and a second wavelength of light using a second light source;
splitting, using a splitter, light received by the first light source and the second light source between a first output light path and a second output light path;
splitting, using a set of splitters of a wavelength monitor, incoming light along the second output light path that includes the first wavelength of light and the second wavelength of light into a first portion of the incoming light, a second portion of the incoming light, and a third portion of the incoming light;
generating, using a first Mach-Zehnder interferometer (MZI) of the wavelength monitor, a first output signal of a plurality of output signals from the first portion of the incoming light;
generating, using a second MZI of the wavelength monitor, a second output signal of a plurality of output signals from the second portion of the incoming light;
generating, using a third MZI of the wavelength monitor, a third output signal of a plurality of output signals from the third portion of the incoming light; and
determining a power weighted average wavelength of the first wavelength and the second wavelength using the plurality of output signals.

9. The method of claim 8 , wherein determining the power weighted average wavelength using the plurality of outputs signals comprises:
selecting an output signal of the plurality of output signals; and
determining the power weighted average wavelength using the selected output signal.

10. The method of claim 8 , comprising:
providing an adjustment signal to the at least one of the first light source or the second light source to shift at least one of the first wavelength or the second wavelength based on the power weighted average wavelength.

11. The method of claim 8 , wherein:
each of the plurality of outputs signals has a sinusoidal relationship between wavelength and intensity and a corresponding phase; and
the corresponding phases of the plurality of output signals are different.

Assignees

• Apple Inc

Inventors

• Wu Yi-Kuei
• Pelc Jason
• Arbore Mark Alan
• Greening Thomas C
• Terrel Matthew A
• Tu Yongming
• MAHMOUD Mohamed

Classifications

• G02F1/212

  Mach-Zehnder type · CPC title

• G02F1/21 Primary

  by interference · CPC title