CN117724205B - Low-loss resonance-free cascade interlayer coupling structure - Google Patents
Low-loss resonance-free cascade interlayer coupling structure Download PDFInfo
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- CN117724205B CN117724205B CN202410113038.3A CN202410113038A CN117724205B CN 117724205 B CN117724205 B CN 117724205B CN 202410113038 A CN202410113038 A CN 202410113038A CN 117724205 B CN117724205 B CN 117724205B
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- 238000009812 interlayer coupling reaction Methods 0.000 title claims abstract description 19
- 230000000737 periodic effect Effects 0.000 claims abstract description 17
- 239000010410 layer Substances 0.000 claims description 34
- 239000011229 interlayer Substances 0.000 claims description 25
- 238000005452 bending Methods 0.000 claims description 15
- 230000010354 integration Effects 0.000 abstract description 8
- 238000000034 method Methods 0.000 abstract description 7
- 230000008878 coupling Effects 0.000 abstract description 5
- 238000010168 coupling process Methods 0.000 abstract description 5
- 238000005859 coupling reaction Methods 0.000 abstract description 5
- 230000008569 process Effects 0.000 abstract description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 9
- 229910052710 silicon Inorganic materials 0.000 description 9
- 239000010703 silicon Substances 0.000 description 9
- 229910052581 Si3N4 Inorganic materials 0.000 description 8
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 8
- 230000005540 biological transmission Effects 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 238000000411 transmission spectrum Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
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Abstract
The invention discloses a low-loss resonance-free cascade interlayer coupling structure, which is formed by connecting a plurality of periodic units, wherein two adjacent periodic units are connected through a bent waveguide, and the two adjacent periodic units are arranged in a staggered manner. The low-loss resonance-free cascade interlayer coupling structure has the advantages that the adjacent cascade structures are staggered, the coupling efficiency is guaranteed, resonance between end faces is effectively avoided, an ultra-narrow tip is not needed, the process requirement is reduced, the size of a device is not needed to be increased, and high integration is guaranteed.
Description
Technical Field
The invention relates to the technical field of optical communication, in particular to a low-loss resonance-free cascade interlayer coupling structure.
Background
Because the photoelectric integration technology is close to the theoretical limit of moore's law, the photoelectric integration technology with the advantages of high bandwidth, low loss, small size and the like has become an important way for realizing future development. The realization of interference-free transmission of optical signals between different devices plays an important role in the design of integrated optical chips. The design of the high-efficiency interlayer coupler can develop the traditional planar technology into a three-dimensional compact integrated technology. The method breaks the layout limitation of waveguide intersections between devices on a single waveguide layer, thereby greatly increasing the number of devices on a chip and promoting the development of a multilayer photonic integrated circuit.
The conventional interlayer coupler adopts tapered graded waveguides, but in a cascading structure, the end faces of the tips of two tapered waveguides are easy to reflect, resonance is generated, and the coupling efficiency and the transmission loss of the device are affected; to eliminate this resonance, two methods are generally employed: one is to narrow the tip, which has high requirements on the process, and the other is to increase the distance between the two tip end surfaces, which increases the size and is not beneficial to integration.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention provides a low-loss resonance-free cascade interlayer coupling structure, which carries out dislocation cascade on two adjacent interlayer coupling structures through a bent waveguide, thereby ensuring the coupling efficiency, effectively avoiding resonance between end surfaces, avoiding ultra-narrow tips, reducing the process requirements, simultaneously avoiding increasing the size of devices and ensuring high integration level.
The specific technical scheme adopted is as follows:
The low-loss resonance-free cascade interlayer coupling structure comprises a cascade interlayer coupling structure formed by connecting a plurality of periodic units, wherein two adjacent periodic units are connected through a bent waveguide, and the two adjacent periodic units are arranged in a staggered mode.
In a further preferred embodiment of the present invention, the periodic unit includes two curved waveguides, the two curved waveguides are arranged in a staggered manner, and the two curved waveguides are connected by an interlayer coupler.
Further preferably, the bending directions of the two bending waveguides in each periodic unit are the same, so as to ensure that the dislocation distance is large.
Further preferably, the bending directions of the bending waveguides in different period units are the same or opposite.
Further preferably, the curved waveguide comprises an upper layer and a lower layer, and the radius of curvature of the upper layer and the lower layer are the same or different. The curved waveguide is required to meet the requirement of nondestructive transmission, and the dislocation gap of the tip of the tapered waveguide is required to be large enough, namely, the curved radius is larger than the minimum radius curved waveguide of the nondestructive transmission, and meanwhile, the mode fields of the two connected tapered waveguides are required to be free from overlapping; the bending waveguide comprises an upper layer and a lower layer, and the bending radius of the upper layer and the lower layer can be the same or different; the optical path is changed, and the dislocation arrangement of the tips of the tapered waveguides is realized, so that resonance caused by end surface reflection is avoided.
Further preferably, the interlayer coupler comprises an upper layer of forward tapered waveguide and a lower layer of forward tapered waveguide, which are respectively a tapered waveguide and an inverted tapered waveguide. The interlayer coupler is composed of an upper layer of forward tapered waveguide and a lower layer of forward tapered waveguide, ensures that signal light is completely coupled to the reverse tapered waveguide from the forward tapered waveguide, and realizes low-loss or lossless transmission conversion.
Compared with the prior art, the invention has the beneficial effects that:
the low-loss resonance-free cascade interlayer coupling structure provided by the invention has the advantages that two adjacent cascade structures are staggered, and the coupling efficiency is ensured by connecting the adjacent cascade structures through the bent waveguides, so that resonance between end surfaces is effectively avoided, an ultra-narrow tip is not required, the process requirement is reduced, the size of a device is not required to be increased, and the high integration level is ensured.
Drawings
FIG. 1 is a schematic diagram of a non-resonant low-loss cascade interlayer coupling structure in accordance with a first embodiment of the present invention;
FIG. 2 is a schematic diagram of a non-resonant low-loss cascade interlayer coupling structure in a second embodiment of the invention;
FIG. 3 is a graph showing transmission spectrum comparison between a structure and a conventional structure in an embodiment of the present invention;
Reference numerals: 1. a lower layer input waveguide; 2. a first interlayer coupler; 201. a lower tapered waveguide; 202. an upper inverted cone waveguide; 3. an upper layer bending waveguide; 301. the dislocation distance of the upper bent waveguide layer; 4. a second interlayer coupler; 401. a lower inverted cone waveguide; 402. an upper tapered waveguide; 5. a lower layer bending waveguide; 501. the lower layer bends the waveguide dislocation distance.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings, fig. 1 to 3 and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The embodiment is a low-loss resonance-free cascade interlayer coupling structure, which comprises a lower-layer input waveguide 1, a first interlayer coupler 2, an upper-layer bent waveguide 3, a second interlayer coupler 4 and a lower-layer bent waveguide 5, wherein the lower-layer input waveguide 1, the first interlayer coupler 2 consists of a lower-layer tapered waveguide 201 and an upper-layer inverted tapered waveguide 202, the second interlayer coupler 4 consists of a lower-layer inverted tapered waveguide 401 and an upper-layer tapered waveguide 402. The first interlayer coupler 2-the lower bent waveguide 5 are used for forming a periodic unit, and a plurality of periodic units form a cascade interlayer coupler structure.
In this embodiment, the two curved waveguides in one period unit, that is, the upper curved waveguide 3 and the lower curved waveguide 5, are to maintain the same curved direction.
The bending directions of the bending waveguides in different periodic units in the cascade interlayer coupler structure can be the same or opposite.
As shown in fig. 1 and 2, the bending directions of the bent waveguides in different periodic units in the cascade interlayer coupler structure in fig. 1 are different. The bending direction of the bent waveguides in the different periodic units in the cascaded interlayer coupler structure in fig. 2 is the same.
As shown in fig. 1, an example is an interlayer coupler of a silicon waveguide and a silicon nitride waveguide, the lower waveguide is silicon, the upper waveguide is silicon nitride, and the intermediate and cladding materials are silicon oxide. Namely, the lower-layer input waveguide 1 is a silicon waveguide, and the upper-layer curved waveguide 3 is a silicon oxide curved waveguide.
The signal light is input from a silicon waveguide (lower layer input waveguide 1) and passes through a first interlayer coupler 2, wherein the silicon waveguide is gradually narrowed, the light field constraint capacity is weaker, the mode field is gradually expanded to a silicon nitride layer, the silicon nitride waveguide is wider, the constraint energy is gradually increased, and the light field in the silicon waveguide is gradually transferred to the silicon nitride waveguide; then, the optical path is shifted through the silicon nitride curved waveguide (upper curved waveguide 3) and enters the second interlayer coupler 4. When the silicon nitride layer is relatively thin, its mode spot is large, and it covers the underlying silicon waveguide. At the interface of the curved silicon nitride waveguide (upper curved waveguide 3) and the second interlayer coupler 4, there is a refractive index abrupt cross section from silicon dioxide to silicon, where light is reflected and transmitted back perpendicular to the cross section. Meanwhile, due to the existence of the bent waveguide, the optical path is deviated, and the reflected signal cannot return to the tip end face of the silicon waveguide in the first interlayer coupler 2, so that resonance is avoided.
As shown in fig. 3, with the same design parameters, the conventional dislocation-free structure is that two adjacent interlayer couplers are connected by adopting a straight waveguide, the tips of the waveguides are directly opposite, and the transmission spectrum is shown as a broken line in the figure, so that obvious resonance phenomenon exists; the staggered arrangement structure is adopted, namely, two adjacent interlayer couplers are connected by adopting a bent waveguide, the tip of the waveguide is staggered, the transmission spectrum is as shown in implementation, and the transmission is flat and has no resonance and keeps low loss.
According to the low-loss resonance-free cascade interlayer coupling structure, two adjacent interlayer coupling mechanisms are connected through the bent waveguide to form a staggered cascade structure, so that the coupling efficiency is guaranteed, resonance between end faces is effectively avoided, an ultra-narrow tip is not needed, the process requirement is reduced, the size of a device is not needed to be increased, and high integration level is guaranteed. If the straight waveguides are connected, the straight waveguides need to be long to achieve similar effects, and the curved waveguides do not need to be long, so that the original length is maintained, and the integration is ensured.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (4)
1. The cascade interlayer coupling structure is characterized by being formed by connecting a plurality of periodic units, wherein two adjacent periodic units are connected through a bent waveguide, and the two adjacent periodic units are arranged in a staggered manner; the periodic unit comprises two curved waveguides which are arranged in a staggered way up and down, and the two curved waveguides are connected through an interlayer coupler; the interlayer coupler comprises an upper layer of forward and reverse tapered waveguides and a lower layer of forward and reverse tapered waveguides, wherein the forward and reverse tapered waveguides are respectively tapered waveguides and reverse tapered waveguides.
2. The low-loss, resonance-free cascading interlayer coupling structure according to claim 1, wherein the bending directions of the two bending waveguides in each period unit are the same.
3. The low-loss, resonance-free, cascade interlayer coupling structure according to claim 1, wherein the bending directions of the bent waveguides in different period units are the same or opposite.
4. The low-loss, resonance-free, cascade interlayer coupling structure according to claim 1, wherein the curved waveguide comprises upper and lower layers having the same or different radius of curvature.
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| CN108693602A (en) * | 2018-06-07 | 2018-10-23 | 上海理工大学 | A kind of three-dimensionally integrated more microcavity resonator, filter devices of silicon nitride and preparation method thereof |
| CN113406743A (en) * | 2021-06-15 | 2021-09-17 | 吉林大学 | Multilayer stack reconfigurable photonic integrated signal cross coupler |
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| JP2015169766A (en) * | 2014-03-06 | 2015-09-28 | 日本電信電話株式会社 | polarization rotation circuit |
| CN106199836B (en) * | 2016-07-21 | 2019-01-25 | 浙江大学 | A Bandwidth Tunable Filter Based on Silicon Waveguide Grating |
| US20190025506A1 (en) * | 2017-07-18 | 2019-01-24 | Finisar Corporation | Polarization splitter rotator |
| CN113496281B (en) * | 2020-03-19 | 2025-03-07 | 光子智能私营科技有限公司 | Optoelectronic computing system |
| US11579367B2 (en) * | 2021-02-10 | 2023-02-14 | Alpine Optoelectronics, Inc. | Integrated waveguide polarizer |
| CN112904478B (en) * | 2021-03-31 | 2021-12-03 | 西南交通大学 | U-shaped waveguide connected two-stage asymmetric directional coupler type light polarization beam splitting rotator |
| CN113933932A (en) * | 2021-09-30 | 2022-01-14 | 中航光电科技股份有限公司 | A Design Method for Multilayer Waveguide Routing and Switching Based on Directional Coupling |
| CN115639646B (en) * | 2022-10-27 | 2025-01-03 | Nano科技(北京)有限公司 | A silicon photonic chip end coupler and output control method thereof |
| CN115857086B (en) * | 2023-03-02 | 2023-05-12 | 北京航空航天大学 | Low-loss four-level symmetrical optical waveguide ring on single substrate |
| CN115857098B (en) * | 2023-03-02 | 2023-05-09 | 北京航空航天大学 | Optical circulator on silicon substrate |
| CN116736564A (en) * | 2023-06-07 | 2023-09-12 | 桂林电子科技大学 | Polymer three-dimensional waveguide mode optical switch based on graphene electrode |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108693602A (en) * | 2018-06-07 | 2018-10-23 | 上海理工大学 | A kind of three-dimensionally integrated more microcavity resonator, filter devices of silicon nitride and preparation method thereof |
| CN113406743A (en) * | 2021-06-15 | 2021-09-17 | 吉林大学 | Multilayer stack reconfigurable photonic integrated signal cross coupler |
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