Multi-mode optical waveguides with deviations in geometric features to improve performance

Patent metadata

Field	Value
Publication number	US-2026072216-A1
Application number	US-202418883035-A
Country	US
Kind code	A1
Filing date	Sep 12, 2024
Priority date	Sep 12, 2024
Publication date	Mar 12, 2026
Grant date	—

Abstract

Systems and methods are provided for designing and fabricating a multi-mode waveguide, such as a waveguide incorporated in a Multi-Mode Interferometer (MMI) device having at least one multi-mode waveguide. According to one implementation, a multi-mode waveguide includes one or more side boundary sections that are non-parallel to a propagation axis of the multi-mode waveguide. In another implementation, a multi-mode waveguide having a propagation axis extending therethrough includes a top planar boundary parallel to the propagation axis and a bottom planar boundary parallel to the propagation axis. Furthermore, the multi-mode waveguide includes a first side boundary having at least one section that is non-parallel to the propagation axis with deviations in geometric features associated therewith. Such deviations are selected based on one or more performance metrics, for improvement thereof.

First claim

What is claimed is:

1 . A multi-mode waveguide having a propagation axis extending therethrough, the multi-mode waveguide comprising:
a top planar boundary parallel to the propagation axis; a bottom planar boundary parallel to the propagation axis; and a first side boundary having at least one section that is non-parallel to the propagation axis with deviations in geometric features associated therewith.

2 . The multi-mode waveguide of claim 1 , further comprising a second side boundary opposite of the first side boundary, the second side boundary having at least one section that is non-parallel to the propagation axis with deviations in geometric features associated therewith.

3 . The multi-mode waveguide of claim 2 , wherein the first and second side boundaries each include multiple sections that are non-parallel to the propagation axis with deviations in geometric features associated therewith.

4 . The multi-mode waveguide of claim 3 , wherein an arrangement of the multiple sections of the first and second side boundaries results in the top planar boundary and bottom planar boundary essentially forming a butterfly-like shape.

5 . The multi-mode waveguide of claim 3 , wherein the multi-mode waveguide includes a rectangular cross-section that varies along its length.

6 . The multi-mode waveguide of claim 1 , wherein the multi-mode waveguide is a first multi-mode waveguide connected directly to a second multi-mode waveguide to form a device having the functionality of an optical hybrid mixer.

7 . The multi-mode waveguide of claim 6 , further comprising multiple input ports at an input face plate of the first multi-mode waveguide, a first set of output ports at an output face plate of the first multi-mode waveguide, and a second set of output ports at an output face plate of the second multi-mode waveguide.

8 . The multi-mode waveguide of claim 7 , wherein each of the multiple input ports is larger than each of the first and second sets of output ports.

9 . The multi-mode waveguide of claim 7 , wherein the multiple input ports are offset from a natural spacing arrangement along the input face plate of the first multi-mode waveguide, and wherein the first and second sets of output ports are offset from a natural spacing arrangement along the output face plates of the first and second multi-mode waveguides.

10 . The multi-mode waveguide of claim 6 , wherein the first multi-mode waveguide is a 2×4 waveguide having two inputs and four outputs, wherein the second multi-mode waveguide is a 2×2 waveguide having two inputs and two outputs, and wherein two of the four outputs of the 2×4 waveguide are configured to propagate optical signals directly to the two inputs of the 2×2 waveguide.

11 . The multi-mode waveguide of claim 6 , wherein the second multi-mode waveguide includes a second top planar boundary and a second bottom planar boundary parallel to a second propagation axis of the second multi-mode waveguide and further includes one or more side boundaries each having at least one section that is non-parallel to the second propagation axis.

12 . The multi-mode waveguide of claim 11 , wherein the second propagation axis of the second multi-mode waveguide is angled with respect to the propagation axis of the first multi-mode waveguide.

13 . The multi-mode waveguide of claim 1 , wherein the geometric features of the first side boundary are configured to improve transmission characteristics with respect to one or more of a) splitting optical signals substantially evenly to a plurality of output ports, b) providing desired equal phase offsets of the optical signals at the plurality of output ports when the multi-mode waveguide in used in an optical hybrid, and c) providing relatively low loss.

14 . The multi-mode waveguide of claim 1 , further comprising one or more single-mode input ports and one or more single-mode output ports with deviations in geometric features associated therewith.

15 . The multi-mode waveguide of claim 1 , wherein the multi-mode waveguide has a non-rectangular, non-parallelogram, and non-trapezoidal profile.

16 . The multi-mode waveguide of claim 1 , wherein the multi-mode waveguide is relatively flat and is fabricated on an optical integrated circuit board.

17 . The multi-mode waveguide of claim 1 , wherein the top planar boundary is parallel with the bottom planar boundary.

18 . The multi-mode waveguide of claim 1 , wherein the geometric features of the first side boundary are determined based on
determining values for the geometric features, creating a waveguide simulation with the values, changing the values based on results of the waveguide simulation, and repeating the creating and changing steps until the waveguide simulation meets a set of performance metrics.

19 . A method for simulating geometric features of a side boundary of a waveguide, the process comprising steps of:
determining values for the geometric features, creating a waveguide simulation with the values, changing the values based on results of the waveguide simulation, and repeating the creating and changing steps until the waveguide simulation meets a set of performance metrics.

20 . An optical mixer comprising:
a first multi-mode waveguide and a second multi-mode waveguide; a plurality of input ports connected to the first multi-mode waveguide; and a plurality of output ports each connected to one of the first multi-mode waveguide and the second multi-mode waveguide, wherein one or more geometric features of any of the first multi-mode waveguide, the second multi-mode waveguide, the plurality of input ports, and the plurality of output ports include deviations selected based on one or more performance metrics.

Assignees

• Ciena Corp

Inventors

• Painchaud Yves

Classifications

• G02B6/2938

  for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM · CPC title

• G02B6/29344 Primary

  operating by modal interference or beating, i.e. of transverse modes, e.g. zero-gap directional coupler, MMI · CPC title

• G02B6/2813

  based on multimode interference effect, i.e. self-imaging · CPC title

• G02B6/125

  Bends, branchings or intersections · CPC title

• G02B27/0012 Primary

  Optical design, e.g. procedures, algorithms, optimisation routines · CPC title