CN115390189A - Planar optical cross waveguide based on adjoint method - Google Patents
Planar optical cross waveguide based on adjoint method Download PDFInfo
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- CN115390189A CN115390189A CN202211341659.4A CN202211341659A CN115390189A CN 115390189 A CN115390189 A CN 115390189A CN 202211341659 A CN202211341659 A CN 202211341659A CN 115390189 A CN115390189 A CN 115390189A
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- optical cross
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- 230000003287 optical effect Effects 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000000463 material Substances 0.000 claims description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000010703 silicon Substances 0.000 claims description 4
- 235000012239 silicon dioxide Nutrition 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 230000007704 transition Effects 0.000 claims description 4
- 230000008569 process Effects 0.000 abstract description 7
- 238000003780 insertion Methods 0.000 abstract description 6
- 230000037431 insertion Effects 0.000 abstract description 6
- 238000005457 optimization Methods 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/125—Bends, branchings or intersections
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12035—Materials
- G02B2006/12061—Silicon
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12083—Constructional arrangements
- G02B2006/12097—Ridge, rib or the like
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The invention discloses a planar optical cross waveguide based on a adjoint method, which comprises a waveguide layer and a waveguide periphery, wherein the waveguide periphery is positioned outside the waveguide layer, the waveguide layer is in a cross structure and consists of a central waveguide and four branch waveguides, and the four branch waveguides are respectively positioned at the periphery of the central waveguide; the outline of the branch waveguide is formed by a smooth curve which is fit by a plurality of key nodes; key nodes forming the smooth curve are distributed equidistantly along the light propagation direction; the key nodes forming the smooth curve are optimized in distance in the direction perpendicular to the light propagation direction by an adjoint method; the smooth curve is formed by fitting key nodes through linear connection or a spline interpolation method. Compared with other traditional planar optical crossed waveguides, the planar optical crossed waveguide is simpler, has lower requirements on optical basis of designers, can obtain lower insertion loss, can strictly ensure the smoothness of the edge of the waveguide, and ensures that the process can be prepared.
Description
Technical Field
The invention relates to the technical field of integrated optical waveguide crossing, in particular to a planar optical crossing waveguide based on a adjoint method.
Background
In the field of integrated optics, optical cross-waveguides are a crucial device. In multi-port photonic switching chips, photonic computing chips, optical cross waveguides are frequently used to meet complex optical circuit wiring requirements. The function of the optical cross waveguide is to realize low-loss and low-crosstalk transmission by two optical waveguides which are vertically and crossly arranged. The traditional design method of the planar optical cross waveguide based on the principles of beam synthesis, multimode interference coupler, sub-wavelength grating and the like needs designers to have better optical basis, more prepositive knowledge, fussy optimization process and higher insertion loss.
Disclosure of Invention
The invention aims to provide a planar optical cross waveguide based on a adjoint method so as to overcome the defects in the prior art.
In order to achieve the purpose, the invention provides the following technical scheme:
the application discloses a planar optical cross waveguide based on a adjoint method, which comprises a waveguide layer and a waveguide periphery, wherein the waveguide periphery is positioned outside the waveguide layer, the waveguide layer is of a cross structure and consists of a central waveguide and four branch waveguides, and the four branch waveguides are respectively positioned at the periphery of the central waveguide; the outline of the branch waveguide is formed by a smooth curve which is fit by a plurality of key nodes; key nodes forming the smooth curve are distributed equidistantly along the light propagation direction; the key nodes forming the smooth curve are optimized in distance in the direction perpendicular to the light propagation direction by an adjoint method; the smooth curve is formed by fitting key nodes through linear connection or a spline interpolation method.
Preferably, the material refractive index of the waveguide layer is larger than the material refractive index of the waveguide periphery.
Preferably, the waveguide layer is made of silicon, and the material on the periphery of the waveguide is silicon dioxide.
Preferably, the cross section of the branch waveguide is a strip waveguide with uniform upper and lower widths.
Preferably, the cross section of the branched waveguide is a ridge waveguide with inconsistent upper and lower widths.
Preferably, the port width of the branch waveguide is smaller than the width of the central waveguide.
Preferably, a vertical transition region is arranged between every two adjacent crossed waveguides.
Preferably, the waveguide layer has an axially symmetric property in both the horizontal and vertical directions.
The invention also discloses an optical device which comprises a body and the planar optical cross waveguide based on the adjoint method, wherein the planar optical cross waveguide based on the adjoint method is arranged on the body.
The invention has the beneficial effects that:
compared with other traditional crossed waveguides, the planar optical crossed waveguide based on the adjoint method is simpler in design, concise in optimization process, capable of achieving lower insertion loss and strictly ensuring that the process can be prepared.
The features and advantages of the present invention will be described in detail by embodiments in conjunction with the accompanying drawings.
Drawings
FIG. 1 is a schematic plan view of a companion method based planar optical cross-over waveguide in accordance with the present invention;
FIG. 2 is a schematic representation of two cross-sections of an intersecting waveguide of the present invention;
FIG. 3 is a cross-waveguide optical field transmission diagram of the design of the present invention optimized for the embodiment;
FIG. 4 is an insertion loss spectrum of a crossed waveguide of the design of the present invention optimized for example simulation;
fig. 5 is a cross-talk spectrum of a crossed waveguide of the inventive design optimized by example simulation.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood, however, that the description herein of specific embodiments is only intended to illustrate the invention and not to limit the scope of the invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
Referring to fig. 1, the planar optical cross waveguide based on the adjoint method of the present invention includes a waveguide layer and a waveguide periphery, wherein the waveguide periphery is located outside the waveguide layer, the waveguide layer is in a cross structure and is composed of a central waveguide and four branch waveguides, and the four branch waveguides are respectively located around the central waveguide; the outline of the branched waveguide is formed by a smooth curve which is synthesized by a plurality of key nodes; key nodes forming the smooth curve are distributed equidistantly along the light propagation direction; the key nodes forming the smooth curve are optimized in distance in the direction perpendicular to the light propagation direction by an adjoint method; the smooth curve is formed by fitting key nodes through linear connection or a spline interpolation method.
In a possible embodiment, the material refractive index of the waveguide layer is larger than the material refractive index of the waveguide periphery. The waveguide layer is made of silicon, and the material on the periphery of the waveguide is silicon dioxide.
In a possible embodiment, the cross section of the branched waveguide is a strip waveguide with uniform upper and lower widths, as shown in fig. 2 (b);
in a possible embodiment, the cross section of the branched waveguide is a ridge waveguide with inconsistent upper and lower widths, as shown in fig. 2 (a);
in one possible embodiment, the port width of the branch waveguide is smaller than the width of the central waveguide.
In a possible embodiment, a section of tiny vertical transition region is arranged between every two adjacent crossed waveguides; to ensure that the crossing portion does not create sharp corners during the optimization process, which is not easily manufacturable by CMOS processes.
In a possible embodiment, the waveguide layer has an axially symmetric property in both the horizontal and vertical directions.
Example (b):
as shown in fig. 2 (a), the branched waveguide is a ridge waveguide, the waveguide layer material is silicon, the cladding material is silicon dioxide, the waveguide slab thickness H2 is 90nm, and the waveguide overall thickness H1 is 220nm.
As shown in fig. 1, for each branching waveguide, the waveguide entrance width W0 is fixed to 500nm, the waveguide intersection region width W1 is fixed to 2000nm, and the lateral span L1 from the first key node to the last key node is fixed to 9 μm; in the embodiment, 19 key nodes are arranged at equal intervals along the x direction and are connected by a quadratic spline interpolation method, the head key node and the tail key node are kept fixed in optimization, and the x coordinate of each key node is also kept fixed in optimization; the cross waveguide vertical transition region length L0 was fixed at 50nm.
In this embodiment, by means of 3-dimensional FDTD simulation software, a 1310nm wavelength transverse electric fundamental mode (TE 0) light is input to the 1 port, and the transverse electric fundamental mode power received by the 2 ports is used as an optimized quality Feature (FOM), and the y-coordinate of the middle 17 free nodes is optimized by using a adjoint optimization method based on the gradient descent principle.
The finally optimized mode converter structure is shown in fig. 1, and has a smooth waveguide edge shape and is easy to process and prepare; the light field transmission diagram obtained by 3-dimensional FDTD simulation is shown in FIG. 3. The simulated insertion loss and crosstalk spectrum is shown in fig. 4 and fig. 5, the cross waveguide designed by the invention obtains the insertion loss of 0.0038dB and the crosstalk of-51.6 dB at 1310nm, and the cross waveguide designed by the invention has very low loss and crosstalk.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. A planar optical cross-waveguide based on the adjoint method, comprising a waveguide layer and a waveguide periphery, said waveguide periphery being located outside the waveguide layer, characterized in that: the waveguide layer is of a cross structure and consists of a central waveguide and four branch waveguides, and the four branch waveguides are respectively positioned on the periphery of the central waveguide; the outline of the branched waveguide is formed by a smooth curve which is synthesized by a plurality of key nodes; key nodes forming the smooth curve are distributed equidistantly along the light propagation direction; the key nodes forming the smooth curve are optimized in distance in the direction perpendicular to the light propagation direction by an adjoint method; the smooth curve is formed by fitting key nodes through linear connection or spline interpolation.
2. The adjoint-based planar optical cross waveguide of claim 1, wherein: the material refractive index of the waveguide layer is greater than the material refractive index of the waveguide periphery.
3. The adjoint-based planar optical cross waveguide of claim 2, wherein: the waveguide layer is made of silicon, and the material on the periphery of the waveguide is silicon dioxide.
4. The adjoint-based planar optical cross waveguide of claim 1, wherein: the cross section of the branch waveguide is a strip waveguide with the same upper and lower widths.
5. The adjoint-based planar optical cross waveguide of claim 1, wherein: the cross section of the branch waveguide is a ridge waveguide with inconsistent upper and lower widths.
6. The adjoint-based planar optical cross waveguide of claim 1, wherein: the port width of the branch waveguide is smaller than the width of the central waveguide.
7. The adjoint-based planar optical cross waveguide of claim 1, wherein: and a vertical transition region is arranged between every two adjacent crossed waveguides.
8. The adjoint-based planar optical cross waveguide of claim 1, wherein: the waveguide layer has axial symmetry properties in both the horizontal and vertical directions.
9. An optical device, characterized by: the optical device includes a body and a adjoint-based planar optical cross-over waveguide of any one of claims 1-6, wherein the adjoint-based planar optical cross-over waveguide is disposed on the body.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211341659.4A CN115390189A (en) | 2022-10-31 | 2022-10-31 | Planar optical cross waveguide based on adjoint method |
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| CN202211341659.4A CN115390189A (en) | 2022-10-31 | 2022-10-31 | Planar optical cross waveguide based on adjoint method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116774351A (en) * | 2023-08-21 | 2023-09-19 | 之江实验室 | Lithium niobate-based optical power distributor with arbitrary proportion and design method |
| CN117008251A (en) * | 2023-10-07 | 2023-11-07 | 之江实验室 | Vertical cross waveguide, forming method thereof and photonic integrated circuit |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114047578A (en) * | 2022-01-12 | 2022-02-15 | 季华实验室 | Waveguide layer and cross waveguide |
| CN114755757A (en) * | 2022-06-15 | 2022-07-15 | 之江实验室 | TM0-TE1 optical mode converter and optical device based on double-layer curve edge waveguide structure |
| CN115166902A (en) * | 2022-07-12 | 2022-10-11 | 无锡芯光互连技术研究院有限公司 | Waveguide layer and multimode interference cross waveguide thereof |
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- 2022-10-31 CN CN202211341659.4A patent/CN115390189A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114047578A (en) * | 2022-01-12 | 2022-02-15 | 季华实验室 | Waveguide layer and cross waveguide |
| CN114755757A (en) * | 2022-06-15 | 2022-07-15 | 之江实验室 | TM0-TE1 optical mode converter and optical device based on double-layer curve edge waveguide structure |
| CN115166902A (en) * | 2022-07-12 | 2022-10-11 | 无锡芯光互连技术研究院有限公司 | Waveguide layer and multimode interference cross waveguide thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116774351A (en) * | 2023-08-21 | 2023-09-19 | 之江实验室 | Lithium niobate-based optical power distributor with arbitrary proportion and design method |
| CN117008251A (en) * | 2023-10-07 | 2023-11-07 | 之江实验室 | Vertical cross waveguide, forming method thereof and photonic integrated circuit |
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Application publication date: 20221125 |
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