Interferometer filters with compensation structure

Patent metadata

Field	Value
Publication number	US-11048041-B2
Application number	US-201916599526-A
Country	US
Kind code	B2
Filing date	Oct 11, 2019
Priority date	May 21, 2019
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

A Mach-Zehnder interferometer (MZI) filter comprising one or more passive compensation structures are described. The passive compensation structures yield MZI filters that are intrinsically tolerant to perturbations in waveguide dimensions and/or other ambient conditions. The use of n+1 waveguide widths can mitigate n different sources of perturbation to the filter. The use of at least three different waveguide widths for each Mach-Zehnder waveguide can alleviate sensitivity of filter performance to random width or temperature variations. A tolerance compensation portion is positioned between a first coupler section and a second coupler section, wherein the tolerance compensation portion includes a first compensation section having a second width, a second compensation section having a third width and a third compensation section having a fourth width, wherein the fourth width is greater than the third width and the third width is greater than the second width.

First claim

What is claimed is:

1. A method for making a Mach-Zehnder interferometer (MZI) filter, the method comprising:
fabricating a first waveguide having a first length and one or more first compensation sections positioned along the first length, wherein each first compensation section of the one or more first compensation sections includes a respective width; and
fabricating a second waveguide having a second length and two or more second compensation sections positioned along the second length, wherein each second compensation section of the one or more second compensation sections includes a respective increase in width of the second waveguide.

2. The method of claim 1 wherein a sum of the one or more first compensation sections and the two or more second compensation sections is one greater than a selected number of perturbations.

3. The method of claim 2 wherein the selected number of perturbations is three and the sum of the one or more first compensation sections and the two or more second compensation sections is five.

4. The method of claim 2 wherein the selected number of perturbations are selected from a manufacturing tolerance variation in a width of each of the first and the second waveguides, a manufacturing tolerance variation in a thickness of each of the first and the second waveguides and a temperature variation in each of the first and the second waveguides.

5. The method of claim 1 wherein the first length and the second length extend between a first coupler section and a second coupler section.

6. The method of claim 1 wherein the first waveguide has a constant first width along the first length, and the second waveguide has an initial second compensation section having a constant second width, a middle second compensation section having a constant third width, and a final second compensation section having a constant fourth width.

7. The method of claim 6 wherein the second compensation sections are arranged symmetrically and include a pair of initial second compensation sections and a pair of middle second compensation sections.

8. The method of claim 1 wherein the one or more first compensation sections and the two or more second compensation sections reduce a shift in a frequency response of the MZI filter due to a variation in a width of the first waveguide and a variation in a width of the second waveguide.

9. An optical filter comprising:
a first waveguide extending between a first coupler section and a second coupler section; and
a second waveguide extending between the first coupler section and the second coupler section and including at least two compensation sections, each having an increase in a width of the second waveguide.

10. The optical filter of claim 9 wherein the first and second coupler sections and the first and second waveguides comprise a Mach-Zehnder interferometer (MZI) filter.

11. The optical filter of claim 10 wherein the second waveguide includes a first compensation section having a first width, a second compensation section having a second width and a third compensation section having a third width, wherein the third width is greater than the second width and the second width is greater than the first width.

12. The optical filter of claim 11 wherein the second waveguide includes a fourth compensation section having the second width and a fifth compensation section having the first width.

13. The optical filter of claim 10 wherein the at least two compensation sections are configured to reduce a shift in a frequency response of the MZI filter due to variations in a width of the first waveguide and variations in a width of the second waveguide.

14. The optical filter of claim 13 wherein the at least two compensation sections have a number of waveguide widths that are greater than a predetermined number of perturbations.

15. The optical filter of claim 9 wherein the at least two compensation sections include a respective taper portion positioned between each of the increases in width of the second waveguide.

16. A method for making a Mach-Zehnder interferometer (MZI) filter comprising:
fabricating a first waveguide having a first length and a first continuous width; and
fabricating a second waveguide having a second length and a plurality of widths along the second waveguide;
wherein the first and the second waveguides simultaneously satisfy:

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Assignees

• Psiquantum Corp

Inventors

• RAVI Koustuban
• Thompson Mark
• Dudley Eric

Classifications

• G02B2006/12061

  Silicon · CPC title

• G02B2006/12159

  Interferometer · CPC title

• G02B6/29355

  Cascade arrangement of interferometers · CPC title

• G02B6/12007 Primary

  forming wavelength selective elements, e.g. multiplexer, demultiplexer · CPC title

• G02B6/1228

  Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305) · CPC title