阅读说明：本技术 一种基于石墨烯和三层超表面的耦合器结构及制备方法 (Graphene and three-layer super-surface-based coupler structure and preparation method ) 是由 刘敏 胡晓 陈代高 肖希 于 2019-09-10 设计创作，主要内容包括：一种基于石墨烯和三层超表面的耦合器结构,涉及光子集成器件领域,包括：互不接触的至少一个第一层超表面、至少一个第二层超表面以及一第三层超表面,第三层超表面位于最下方；绝缘体结构层；分别设置在绝缘体结构层上、下表面的石墨烯结构层和衬底；第一、二层超表面的折射率大于第一绝缘层,第三层超表面的折射率大于第一子结构的折射率。本发明设计了三层超表面层和石墨烯结构层,通过三层超表面层调整光束传播路径和各层有效折射率,第一子结构与第三层超表面的折射率对比度减小,有效增大耦合器的工作带宽；石墨烯结构层能够进一步增大耦合器的工作带宽,三层超表面矩阵单元阵列排列结构能有效增大耦合器的耦合效率。(A coupler structure based on graphene and three-layer super-surface relates to the field of photonic integrated devices and comprises: at least one first-layer super surface, at least one second-layer super surface and a third-layer super surface which are not in contact with each other, wherein the third-layer super surface is positioned at the lowest part; an insulator structure layer; the graphene structure layer and the substrate are respectively arranged on the upper surface and the lower surface of the insulator structure layer; the refractive index of the first and second super-surfaces is greater than that of the first insulating layer, and the refractive index of the third super-surface is greater than that of the first substructure. According to the invention, three super-surface layers and a graphene structure layer are designed, a light beam propagation path and effective refractive indexes of all layers are adjusted through the three super-surface layers, the refractive index contrast ratio of a first substructure to a third super-surface layer is reduced, and the working bandwidth of the coupler is effectively increased; the graphene structure layer can further increase the working bandwidth of the coupler, and the three-layer super-surface matrix unit array arrangement structure can effectively increase the coupling efficiency of the coupler.)

1. A graphene-based and three-layer super-surface coupler structure, comprising:

at least one first-layer super surface, at least one second-layer super surface and a third-layer super surface which are not in contact with each other, wherein the third-layer super surface is positioned below the first-layer super surface and the second-layer super surface, and the first-layer super surface, the second-layer super surface and the third-layer super surface all adopt a rectangular array structure formed by a plurality of basic units;

the insulator structure layer is composed of a first insulating layer wrapping the first super-surface and the second super-surface and a second insulating layer wrapping the third super-surface, the first super-surface, the second super-surface and the first insulating layer form a first substructure, and the third super-surface and the second insulating layer form a second substructure;

the graphene structure layer and the substrate are respectively arranged on the upper surface and the lower surface of the insulator structure layer;

the refractive indexes of the first and second super surfaces are larger than that of the first insulating layer, and the refractive index of the third super surface is larger than that of the first substructure.

2. The graphene-based and three-layer super-surface coupler structure of claim 1, wherein the refractive indices of the first insulating layer and the second insulating layer are the same.

3. The graphene-and three-layer-super-surface-based coupler structure of claim 1, wherein a difference in refractive index between the third layer super-surface and the second insulating layer is greater than a difference in refractive index between the first layer super-surface and the first insulating layer;

the difference in refractive index between the third layer super surface and the second insulating layer is greater than the difference in refractive index between the second layer super surface and the first insulating layer.

4. The graphene-and tri-layer super surface-based coupler structure of claim 1, wherein the graphene structure layer is comprised of at least one graphene layer stacked arrangement.

5. The graphene-and three-layer super-surface based coupler structure of claim 1, wherein the insulator structure layer has a lower refractive index than the graphene structure layer.

6. The graphene-and three-layer super-surface based coupler structure of claim 1, wherein the first layer super-surface comprises a plurality of first rectangular elementary cells, a plurality of the first rectangular elementary cells constituting a rectangular array, in which,

the transverse length of the first rectangular basic unit of each row is kept unchanged or at least partially decreased, and the transverse interval of the adjacent first rectangular basic units is kept unchanged or at least partially increased;

the longitudinal length of the first rectangular basic units of each column is kept constant or at least partially decreased, and the longitudinal interval between the adjacent first rectangular basic units is kept constant or at least partially increased.

7. The graphene-based and three-layer super-surface coupler structure according to claim 1, wherein the second layer super-surface comprises a plurality of second rectangular basic units, the plurality of second rectangular basic units form a rectangular array, in the rectangular array, the lateral length of the second rectangular basic units in each row is constant or at least partially decreased, and the lateral spacing between adjacent second rectangular basic units is constant or at least partially increased;

the longitudinal length of the second rectangular basic units of each column is kept constant or at least partially decreased, and the longitudinal interval between the adjacent second rectangular basic units is kept constant or at least partially increased.

8. The graphene-and three-layer-super-surface-based coupler structure of claim 1, wherein the third layer super-surface comprises a multi-aperture parallel-plate waveguide comprised of a plurality of perforated base units, a plurality of the perforated base units comprising a rectangular array, wherein in the rectangular array,

the length of the transverse holes of the basic units with holes in each row is kept constant or at least partially increased, and the interval between the transverse holes of the adjacent basic units with holes is kept constant or at least partially decreased;

the longitudinal hole length of the basic units with holes in each column is kept constant or at least partially increased, and the longitudinal hole interval of the adjacent basic units with holes is kept constant or at least partially decreased.

9. A preparation method of a coupler based on graphene and a three-layer super surface is characterized by comprising the following steps:

step S1, forming a third super-surface by single deposition, and forming an insulating layer, a second super-surface and a first super-surface by multiple depositions to form at least one first super-surface, at least one second super-surface and a third super-surface on the substrate, wherein the first super-surface, the second super-surface and the third super-surface are not in contact with each other, the third super-surface is positioned below the first super-surface and the second super-surface, and the insulating layer forms an insulator structure layer wrapping all the first super-surface, the second super-surface and the third super-surface;

step S2, depositing a graphene structure layer on the upper surface of the insulator structure layer;

the first-layer super surface, the second-layer super surface and the third-layer super surface are all in a rectangular array structure formed by a plurality of basic units;

the insulator structure layer is composed of a first insulating layer wrapping the first super surface and the second super surface and a second insulating layer wrapping the third super surface, the first super surface, the second super surface and the first insulating layer form a first substructure, and the third super surface and the second insulating layer form a second substructure;

the refractive indexes of the first and second super surfaces are larger than that of the first insulating layer, and the refractive index of the third super surface is larger than that of the first substructure.

10. The method of claim 9, wherein the difference in refractive index between the third super surface and the second insulating layer is greater than the difference in refractive index between the first super surface and the first insulating layer;

the difference in refractive index between the third layer super surface and the second insulating layer is greater than the difference in refractive index between the second layer super surface and the first insulating layer.

Technical Field

The invention relates to the field of photonic integrated devices, in particular to a coupler structure based on graphene and three-layer super-surface and a preparation method thereof.

Background

In the field of photonic integrated devices, couplers are used as windows for transmitting optical path information between devices and between the devices and the outside, and are important photonic integrated passive devices. The most important reference performance indicators for coupler goodness are three: coupling efficiency, bandwidth and polarization dependence. How to improve the coupling efficiency, increase the coupling bandwidth and reduce the polarization dependence is the key for designing and researching the coupling device with excellent performance.

There are several drawbacks in existing couplers, such as insufficient coupling efficiency, insufficient bandwidth, and polarization sensitivity.

Disclosure of Invention

Aiming at the defects of the existing coupler, namely the problems of low coupling efficiency, low bandwidth and polarization sensitivity, the invention aims to provide a high-performance multifunctional coupler structure based on graphene and three layers of super surfaces, which can effectively increase the working bandwidth of the coupler, improve the coupling efficiency of the coupler and reduce the polarization sensitivity.

In order to achieve the above object, the present invention provides a coupler structure based on graphene and three-layer super-surface, including:

at least one first-layer super surface, at least one second-layer super surface and a third-layer super surface which are not in contact with each other, wherein the third-layer super surface is positioned below the first-layer super surface and the second-layer super surface, and the first-layer super surface, the second-layer super surface and the third-layer super surface all adopt a rectangular array structure formed by a plurality of basic units;

the insulator structure layer is composed of a first insulating layer wrapping the first super-surface and the second super-surface and a second insulating layer wrapping the third super-surface, the first super-surface, the second super-surface and the first insulating layer form a first substructure, and the third super-surface and the second insulating layer form a second substructure;

the graphene structure layer and the substrate are respectively arranged on the upper surface and the lower surface of the insulator structure layer;

the refractive indexes of the first and second super surfaces are larger than that of the first insulating layer, and the refractive index of the third super surface is larger than that of the first substructure.

On the basis of the above technical solution, the refractive indexes of the first insulating layer and the second insulating layer are the same.

On the basis of the technical scheme, the difference of the refractive indexes of the third-layer super surface and the second insulating layer is larger than that of the first-layer super surface and the first insulating layer;

the difference in refractive index between the third layer super surface and the second insulating layer is greater than the difference in refractive index between the second layer super surface and the first insulating layer.

On the basis of the technical scheme, the graphene structure layer is formed by stacking at least one graphene layer.

On the basis of the technical scheme, the refractive index of the insulator structure layer is lower than that of the graphene structure layer.

On the basis of the technical scheme, the first-layer super surface comprises a plurality of first rectangular basic units, the first rectangular basic units form a rectangular array, in the rectangular array,

the transverse length of the first rectangular basic unit of each row is kept unchanged or at least partially decreased, and the transverse interval of the adjacent first rectangular basic units is kept unchanged or at least partially increased;

the longitudinal length of the first rectangular basic units of each column is kept constant or at least partially decreased, and the longitudinal interval between the adjacent first rectangular basic units is kept constant or at least partially increased.

On the basis of the technical scheme, the second-layer super surface comprises a plurality of second rectangular basic units, the second rectangular basic units form a rectangular array, in the rectangular array, the transverse length of each row of the second rectangular basic units is kept unchanged or at least partially decreased, and the transverse interval between every two adjacent second rectangular basic units is kept unchanged or at least partially increased;

the longitudinal length of the second rectangular basic units of each column is kept constant or at least partially decreased, and the longitudinal interval between the adjacent second rectangular basic units is kept constant or at least partially increased.

On the basis of the technical scheme, the third-layer super-surface comprises a porous parallel-plate waveguide, the porous parallel-plate waveguide is composed of a plurality of basic units with holes, a rectangular array is formed by the plurality of basic units with holes, in the rectangular array,

the length of the transverse holes of the basic units with holes in each row is kept constant or at least partially increased, and the interval between the transverse holes of the adjacent basic units with holes is kept constant or at least partially decreased;

the longitudinal hole length of the basic units with holes in each column is kept constant or at least partially increased, and the longitudinal hole interval of the adjacent basic units with holes is kept constant or at least partially decreased.

A preparation method of a coupler based on graphene and a three-layer super surface comprises the following steps:

step S1, forming a third super-surface by single deposition, and forming at least one first super-surface, at least one second super-surface and a third super-surface on the substrate by depositing an insulating layer, the second super-surface and the first super-surface for multiple times, wherein the first super-surface, the second super-surface and the third super-surface are not in contact with each other, the third super-surface is positioned below the first super-surface and the second super-surface, and the insulating layer forms an insulator structure layer wrapping all the first super-surface, the second super-surface and the third super-surface;

step S2, depositing a graphene structure layer on the upper surface of the insulator structure layer;

the first-layer super surface, the second-layer super surface and the third-layer super surface are all in a rectangular array structure formed by a plurality of basic units;

the insulator structure layer is composed of a first insulating layer wrapping the first super surface and the second super surface and a second insulating layer wrapping the third super surface, the first super surface, the second super surface and the first insulating layer form a first substructure, and the third super surface and the second insulating layer form a second substructure;

the refractive indexes of the first and second super surfaces are larger than that of the first insulating layer, and the refractive index of the third super surface is larger than that of the first substructure.

On the basis of the technical scheme, the difference of the refractive indexes of the third-layer super surface and the second insulating layer is larger than that of the first-layer super surface and the first insulating layer;

the difference in refractive index between the third layer super surface and the second insulating layer is greater than the difference in refractive index between the second layer super surface and the first insulating layer.

The invention has the beneficial effects that: the invention designs three super-surface layers and a graphene structure layer, a light beam propagation path and effective refractive indexes of all layers are adjusted through the three super-surface layers, the first super-surface layer and the second super-surface layer are made of materials with refractive indexes slightly larger than that of a first insulating layer wrapping the super-surface layers, the third super-surface layer is made of materials with refractive indexes larger than that of the first super-surface layer and the second super-surface layer, so that the integral effective refractive index of a first substructure formed by the first super-surface layer and the second super-surface layer and a first insulating layer wrapping the first super-surface layer and the second super-surface layer is increased, the refractive index contrast of the first substructure and the third super-surface;

the graphene structural layer can further increase the working bandwidth of the coupler;

the three-layer super-surface matrix unit specific arrangement structure has flexible parameter forms, can improve the mode matching degree between the coupler and the optical fiber, reduces the mode mismatch loss, increases the coupling efficiency and reduces the polarization sensitivity. Forming a multi-functional coupler structure.

Drawings

FIG. 1 is a schematic diagram of a first-layer meta-surface structure of a coupler in an embodiment of the present invention;

FIG. 2 is a schematic diagram of a super-surface structure of a second layer of a coupler according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a super-surface structure of a third layer of a coupler according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a coupler structure according to an embodiment of the present invention;

FIG. 5 is a flow chart of a method of making a coupler according to an embodiment of the present invention;

reference numerals:

the structure comprises a graphene structure layer 1, a first super surface 2, a second super surface 3, a third super surface 4, an insulator structure layer 5, an incident beam 6, a super surface structure 7 and a substrate 8.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "lateral", "longitudinal", "thickness direction", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

The present invention will be described in further detail with reference to the accompanying drawings and examples.

A graphene and three-layer super-surface based coupler structure comprising:

at least one first-layer super surface 2, at least one second-layer super surface 3 and a third-layer super surface 4 which are not in contact with each other, wherein the third-layer super surface 4 is positioned below the first-layer super surface 2 and the second-layer super surface 3, the first-layer super surface 2, the second-layer super surface 3 and the third-layer super surface 4 all adopt a rectangular array structure formed by a plurality of basic units, for example, the first-layer super surface 2 adopts a plurality of first rectangular basic units to form a rectangular array, the second-layer super surface 3 adopts a plurality of second rectangular basic units to form a rectangular array, and the third-layer super surface 4 adopts a plurality of basic units with holes to form a rectangular array;

an insulator structure layer 5 wrapping all the first layer of super-surface 2, the second layer of super-surface 3 and the third layer of super-surface 4, namely a super-surface structure 7 formed by three layers of super-surfaces is formed inside the insulator structure layer 5, the insulator structure layer 5 is composed of a first insulating layer wrapping the first layer of super-surface 2 and the second layer of super-surface 3 and a second insulating layer wrapping the third layer of super-surface 4, the first layer of super-surface 2, the second layer of super-surface 3 and the first insulating layer form a first substructure, and the third layer of super-surface 4 and the second insulating layer form a second substructure;

and the graphene structure layer 1 and the substrate 8 are respectively arranged on the upper surface and the lower surface of the insulator structure layer 5.

The first layer of super surface 2, the second layer of super surface 3 and the third layer of super surface 4 are all in a rectangular array structure formed by a plurality of basic units;

the refractive index of the first and second super-surfaces is greater than that of the first insulating layer, and the refractive index of the third super-surface 4 is greater than that of the first substructure.

In this embodiment, the meta-surface is an artificial layered material with a thickness smaller than the wavelength, and the meta-surface can be regarded as a two-dimensional correspondence of the meta-material. The optical super-surface can regulate and control the characteristics of polarization, phase, amplitude, frequency and the like of electromagnetic waves through a sub-wavelength microstructure, and is a new technology combining optics and nanotechnology.

Due to the unique energy band structure of graphene, graphene has very good optical characteristics, and the absorption rate of single-layer graphene in a wide wavelength range is about 2.3%. In the range of 10 graphene layers, the absorption rate increases by 2.3% for each additional layer. The large-area graphene film also has excellent optical characteristics, and the optical characteristics of the large-area graphene film change along with the change of the thickness of the graphene.

By combining the super-surface and the graphene structure layer 1, the coupling efficiency of the coupler can be improved to a great extent, the coupling bandwidth can be increased, and the polarization correlation can be greatly reduced. Due to the flexible structure, various coupling requirements can be met.

Specifically, incident beam 6 has a variable angle θ. The graphene structure layer 1 can be a single-layer graphene layer and a multi-layer graphene layer, and the coupling bandwidth of the coupler can be effectively ensured by utilizing the optical characteristics of graphene. Taking the first-layer super-surface 2, the second-layer super-surface 3 and the third-layer super-surface 4 as an example, the three-layer super-surface 7 includes the first-layer super-surface 2 and the second-layer super-surface 3 for adjusting the direction and the effective refractive index of an incident light beam 6, and the third-layer super-surface 4 for coupling and transmitting light, and the three-layer super-surfaces are sequentially arranged along the thickness direction.

The three-layer super surface layer and the graphene structure layer 1 are designed, a light beam propagation path and effective refractive indexes of all layers are adjusted through the three-layer super surface layer, the first super surface and the second super surface are made of materials with refractive indexes slightly larger than that of a first insulating layer wrapping the super surfaces, the third super surface 4 is made of materials with refractive indexes larger than that of the first super surface and the second super surface, the overall effective refractive index of a first substructure formed by the first super surface and the second super surface and the first insulating layer wrapping the first super surface and the second super surface is increased, the refractive index contrast of the first substructure and the third super surface 4 is reduced, and the working bandwidth of the coupler is effectively increased;

the graphene structural layer 1 can further increase the working bandwidth of the coupler.

The three super-surfaces all adopt flexible parameter forms of matrix unit specific arrangement structures, so that the matching degree of modes between the coupler and the optical fiber can be improved, the mode mismatch loss is reduced, the coupling efficiency is increased, and the polarization sensitivity is reduced. Forming a multi-functional coupler structure.

Taking the top graphene structure layer 1, the first super surface 2, the second super surface 3, the third super surface 4 and the substrate 8 as an example, which are all one in number and are sequentially arranged from top to bottom, the top graphene structure layer 1 and the first super surface 2 are separated by a distance delta h₁，Δh₁The value is greater than or equal to 0 and less than or equal to 500nm。

The distance delta h between the first layer of super surface 2 and the second layer of super surface 3 along the thickness direction₂，Δh₂0 or more and 500nm or less.

The distance delta h between the second layer super surface 3 and the third layer super surface 4 along the thickness direction₃，Δh₃0 or more and 500nm or less.

The distance delta h between the third super surface 4 and the electrolyte substrate 8 layer along the thickness direction₄，Δh₄Greater than or equal to 1 μm and less than or equal to 3 μm.

The materials of the three super-surface layers are not limited, and the refractive indexes of the materials are not limited as long as the refractive indexes of the first super-surface layer and the second super-surface layer are larger than that of the first insulating layer, and the refractive index of the third super-surface layer 4 is larger than that of the first substructure.

Further, the graphene structure layer 1 is formed by stacking at least one graphene layer.

Specifically, the graphene structure layer 1 may be a single graphene layer or a multi-layer graphene layer, and the coupling bandwidth of the coupler can be effectively ensured by using the optical characteristics of graphene.

Further, the above graphene-based and three-layer super-surface-based coupler structure further includes:

and a substrate 8, wherein the insulating structure layer is provided on an upper surface of the substrate 8.

Further, the refractive index of the insulator structure layer 5 is lower than the refractive index of the graphene structure layer 1, the first super-surface layer 2, the second super-surface layer 3, and the third super-surface layer 4.

Further, the first-layer super-surface 2 comprises a plurality of first rectangular basic units, a plurality of first rectangular basic units form a rectangular array, and in the rectangular array,

the transverse length of the first rectangular basic units in each row is kept unchanged or at least partially decreased, and the transverse interval between the adjacent first rectangular basic units is kept unchanged or at least partially increased;

the longitudinal length of the first rectangular basic units in each column is kept constant or at least partially decreased, and the longitudinal interval between the adjacent first rectangular basic units is kept constant or at least partially increased.

Specifically, referring to fig. 1, a top view of the first layer of the super-surface 2 is shown. The first layer of super-surface 2 comprises first rectangular elementary cells having a transverse length l₁+Δl₁，l₁The value is more than 0 and less than 1 mu m, delta l₁The value is more than or equal to 0 and less than or equal to 200nm, wherein each rectangular basic unit takes the same l₁Taking the same delta l₁Then the lateral length of the first plurality of rectangular elementary cells of the row remains unchanged. Each rectangular basic unit takes the same one₁Taking a different and decreasing Δ l₁I.e. how many first rectangular elementary units there may be different and decreasing al₁The value, then the lateral length of the plurality of first rectangular elementary cells of the row decreases. Each rectangular basic unit takes the same one₁Taking different Δ l₁The lateral lengths of the plurality of first rectangular basic cells of the row may decrease at the partially unchanged portion. The same applies to the lateral spacing, the longitudinal length, the longitudinal spacing and the variation of the lateral length.

The first layer of the hypersurface 2 comprises first rectangular elementary cells having a longitudinal length l₂+Δl₂，l₂The value is more than 0 and less than 1 mu m, delta l₂The value is more than or equal to 0 and less than or equal to 200nm, wherein each rectangular basic unit takes the same l₂Taking the same delta l₂The longitudinal length of the plurality of first rectangular basic cells of the row remains unchanged. Each first rectangular basic unit has the same longitudinal length₂Taking a different and decreasing Δ l₂I.e. how many first rectangular elementary units there may be different and decreasing al₂The value, then the longitudinal length of the plurality of first rectangular basic cells of the row decreases. Each first rectangular basic unit has the same longitudinal length₂Taking different Δ l₂I.e. how many first rectangular elementary units there are possible different deltal₂The longitudinal length of the plurality of first rectangular basic cells of the row may decrease at the partially unchanged portion.

Adjacent first moments contained in the first layer of the super-surface 2The basic unit of the shape is transversely spaced by a distance d₁+Δd₁，d₁A value greater than and/or equal to 30nm and less than 600nm, Δ d₁The value is more than or equal to 0 and less than or equal to 200nm, wherein each rectangular basic unit takes the same d₁Take the same Δ d₁Then the lateral spacing distance of the first plurality of rectangular elementary cells of the row remains unchanged. Each first rectangular basic unit takes the same d₁Take different and increasing Δ d₁I.e. how many first rectangular elementary units there may be different and increasing deltad₁The value, then the lateral separation distance of the first plurality of rectangular elementary cells of the row is incremented. Each first rectangular basic unit takes the same d₁Taking the difference Δ d₁I.e. how many first rectangular elementary units there are possible different deltad₁The value, then the lateral separation distance of the first plurality of rectangular elementary cells of the row is constant or partially increasing.

The first layer of the super-surface 2 comprises adjacent first rectangular basic units which are longitudinally spaced by a distance d₂+Δd₂，d₂A value greater than and/or equal to 30nm and less than 600nm, Δ d₂The value is more than or equal to 0 and less than or equal to 200nm, wherein each rectangular basic unit takes the same d₂Take the same Δ d₂The vertical spacing distance of the plurality of first rectangular basic cells of the row remains unchanged. Each first rectangular basic unit takes the same d₂Take different and increasing Δ d₂I.e. how many first rectangular elementary units there may be different and increasing deltad₂The value is obtained. Each first rectangular basic unit takes the same d₂Taking the difference Δ d₂I.e. how many first rectangular elementary units there are possible different deltad₂The value, then the lateral separation distance of the first plurality of rectangular elementary cells of the row is constant or partially increasing.

Further, the second-layer super-surface 3 includes a plurality of second rectangular basic units, and the plurality of second rectangular basic units form a rectangular array;

the transverse length of the second rectangular basic units in each row is kept unchanged or at least partially decreased, and the transverse interval between the adjacent second rectangular basic units is kept unchanged or at least partially increased;

the longitudinal length of the second rectangular basic units in each column is kept constant or at least partially decreased, and the longitudinal interval between the adjacent second rectangular basic units is kept constant or at least partially increased.

Specifically, referring to fig. 2, a top view of the second layer of the super-surface 3 is shown. The second layer of the super-surface 3 comprises a second rectangular basic unit with a transverse length l₃+Δl₃，l₃The value is more than 0 and less than 1 mu m, delta l₃The value is more than or equal to 0 and less than or equal to 200nm, and each second rectangular basic unit is longitudinally the same as one₃Taking different Δ l₃I.e. how many second rectangular elementary units there are possible different deltal₃The value is obtained. The second layer of the super-surface 3 comprises a second rectangular basic unit with a longitudinal length l₄+Δl₄，l₄The value is more than 0 and less than 1 mu m, delta l₄The value is more than or equal to 0 and less than or equal to 200nm, and each second rectangular basic unit is longitudinally the same as one₄Taking different Δ l₄I.e. how many second rectangular elementary units there are possible different deltal₄The value is obtained.

The first layer of the meta-surface 2 comprises adjacent second rectangular elementary units laterally spaced by a distance d₃+Δd₃，d₃A value greater than and/or equal to 30nm and less than 600nm, Δ d₃The value is more than or equal to 0 and less than or equal to 200nm, wherein each second rectangular basic unit takes the same d₃Taking the difference Δ d₃I.e. how many second rectangular elementary units there are possible different deltad₃The value is obtained. The second layer of the super-surface 3 comprises adjacent second rectangular basic units which are longitudinally spaced by a distance d₄+Δd₄，d₄A value greater than and/or equal to 30nm and less than 600nm, Δ d₄The value is more than or equal to 0 and less than or equal to 200nm, wherein each second rectangular basic unit takes the same d₄Taking the difference Δ d₄I.e. how many second rectangular elementary units there are possible different deltad₄The value is obtained.

Further, the third super-surface 4 comprises a multi-hole parallel-plate waveguide, wherein the multi-hole parallel-plate waveguide is composed of a plurality of basic units with holes, and the basic units with holes form a rectangular array;

the length of the transverse holes of the basic units with holes in each row is kept constant or at least partially increased, and the interval between the transverse holes of the adjacent basic units with holes is kept constant or at least partially decreased;

the longitudinal hole length of the basic units with holes in each row is kept constant or at least partially increased, and the longitudinal hole interval of the adjacent basic units with holes is kept constant or at least partially decreased.

Specifically, referring to fig. 3, a top view of the third layer of the super-surface 4 is shown. The length of the transverse hole of the basic unit with the hole of the porous parallel plate waveguide is l₅+Δl₅，l₅The value is greater than and/or equal to 30nm and less than 600nm, delta l₅The value is more than or equal to 0 and less than or equal to 200nm, and each basic unit with holes is transversely the same₅Taking different Δ l₅I.e. how many perforated basic cells there may be different deltal₅The value is obtained. The length of the longitudinal hole of the basic unit with the hole of the porous parallel plate waveguide is l₆+Δl₆，l₆The value is greater than and/or equal to 30nm and less than 600nm, delta l₆The value is more than or equal to 0 and less than or equal to 200nm, and each basic unit with holes is longitudinally the same as one₆Taking different Δ l₆I.e. how many perforated basic cells there may be different deltal₆The value is obtained.

The distance between the transverse adjacent holes of the basic units with holes of the porous parallel plate waveguide is d₅+Δd₅，d₅The value is more than 0 and less than 1 mu m, delta d₅The value is more than or equal to 0 and less than or equal to 200nm, wherein each basic unit with holes has the same value d₅Taking the difference Δ d₅I.e. how many perforated basic cells there may be different deltad₅The value is obtained. The distance between the longitudinal adjacent holes of the basic units with holes of the porous parallel plate waveguide is d₆+Δd₆，d₆The value is more than 0 and less than 1 mu m, delta d₆The value is more than or equal to 0 and less than or equal to 200nm, wherein each basic unit with holes has the same value d₆Taking the difference Δ d₆I.e. how many perforated basic cells there may be different deltad₆The value is obtained.

A preparation method of a graphene-based and three-layer super-surface coupler comprises the following steps:

step S1, depositing a third super-surface 4 once, and depositing an insulating layer, a first super-surface 2 and a second super-surface 3 multiple times to form at least one first super-surface 2, at least one second super-surface 3 and a third super-surface 4 that are not in contact with each other, where the third super-surface 4 is located below the first super-surface 2 and the second super-surface 3, and the insulating layer deposited multiple times forms an insulator structure layer 5 that wraps all of the first super-surface 2, the second super-surface 3 and the third super-surface 4;

step S2, depositing a graphene structure layer 1 on the upper surface of the insulator structure layer 5.

Each first layer of meta-surface 2 and each second layer of meta-surface 3 is disposed inside the insulator structure layer 5 and is wrapped by the insulator structure layer 5.

First embodiment

A coupler structure based on graphene and three-layer super-surfaces can realize high-performance and multifunctional optical coupling and comprises a top graphene structure layer 1, three-layer super-surfaces (a first-layer super-surface 2, a second-layer super-surface 3 and a third-layer super-surface 4), an insulator structure layer 5 wrapping the three-layer super-surfaces and a bottom electrolyte substrate 8.

The first-layer super-surface 2, the second-layer super-surface 3 and the third-layer super-surface 4 are all single, the three-layer super-surfaces comprise the first-layer super-surface 2 and the second-layer super-surface 3 which are used for adjusting the direction and the effective refractive index of an incident beam 6, and the third-layer super-surface 4 which is used for coupling and transmitting light, and the three-layer super-surfaces are sequentially arranged along the thickness direction. The angle theta of the incident beam 6 is 12.6 deg..

In this embodiment, referring to fig. 1, the number of the first rectangular basic units of the first-layer super-surface 2 is 11. Transverse length of first rectangular basic unitIs 1₁+Δl₁Longitudinal length of l₂+Δl₂. Wherein l₁Taking 182nm,. DELTA.l₁All values are 0, l₂Value and l₁Same, take 182nm,. DELTA.l₂The values are all 0. The first layer of super-surface 2 is laterally spaced from laterally adjacent first rectangular elementary cells by a distance d₁+Δd₁Longitudinally adjacent first rectangular basic units are longitudinally spaced by a distance d₂+Δd₂. Wherein d is₁Values 543nm, Δ d₁Values of 0, d₂Values of 183nm,. DELTA.d₂The values are all 0. Which forms a uniform waveguide array super-surface.

Referring to fig. 2, in the present embodiment, the number of the second rectangular basic units of the second-layer super-surface 3 is 11. The second rectangular basic unit has a transverse length of l₃+Δl₃Longitudinal length of l₄+Δl₄. Wherein l₃Values of 313nm,. DELTA.l₃The transverse values are as follows: 87nm, 112nm, 123nm, 94nm, 84nm, 69nm, 67nm, 46nm, 12nm, 0 and 0; l₄Values of 390nm,. DELTA.l₄The values are all 0. The second layer of super-surface 3 is laterally spaced from the laterally adjacent second rectangular basic cells by a distance d₃+Δd₃Longitudinally adjacent second rectangular basic units are longitudinally spaced by a distance d₄+Δd₄. Wherein d is₃Values 153nm,. DELTA.d₃The transverse values are as follows: 13nm, 0, 30nm, 45nm, 72nm, 78nm, 116nm, 144nm, 161 nm; d₄Values of 183nm,. DELTA.d₄The values are all 0.

Referring to fig. 3, in the present embodiment, the third super-surface layer 4 includes an input light transmission waveguide unit length of 2 μm and an end waveguide unit length of 2 μm; the number of basic unit holes with holes of the porous parallel plate waveguide is 12, and the length of a transverse hole is l₅+Δl₅Longitudinal bore length of l₆+Δl₆Wherein l is₅Values of 138nm,. DELTA.l₅The transverse values are as follows: 0nm, 23nm, 54nm, 97nm, 85nm, 100nm, 137nm, 166 nm; l₆Values of 390nm,. DELTA.l₆The values are all 0. Porous parallel plate waveguide with holesThe distance between adjacent transverse holes is d₅+Δd₅The distance between longitudinally adjacent holes is d₆+Δd₆Wherein d is₅Values 342nm,. DELTA.d₅The transverse values are as follows: 148nm, 133nm, 104nm, 57nm, 70nm, 49nm, 27nm, 0; d₆Values of 183nm,. DELTA.d₆The values are all 0.

During specific preparation, the insulating layer is sequentially deposited on the substrate 8 to prepare a third super surface 4, the insulating layer is continuously deposited, and the insulating layer covering and wrapping the third super surface 4 forms a second insulating layer; and continuously depositing an insulating layer, preparing a second super surface 3, continuously depositing the insulating layer, preparing a first super surface 2, and forming the first insulating layer by covering and wrapping the insulating layer of the second super surface 3 and the insulating layer of the first super surface 2. The first insulating layer and the second insulating layer have the same refractive index. The first insulating layer and the second insulating layer form an insulator structure layer 5, the process is based on the preparation of a substrate 8, and finally, a graphene structure layer 1 is formed on the upper surface of the insulator structure layer 5 to form the whole coupler structure.

The third super-surface 4 is made of a material with a larger refractive index, and will form a larger refractive index contrast with the second insulating layer. The first and second super-surfaces are made of a material with a refractive index slightly larger than that of the first insulating layer wrapping the first and second super-surfaces, so that the overall effective refractive index of a first substructure formed by the first and second super-surfaces and the first insulating layer wrapping the first super-surfaces is increased. Meanwhile, the third-layer super surface is made of a material with a refractive index larger than that of the first-layer super surface and that of the second-layer super surface, the contrast ratio of the refractive index of the first substructure to the refractive index of the third-layer super surface is reduced, and the working bandwidth of the coupler is effectively increased;

the graphene structural layer can further increase the working bandwidth of the coupler.

The changed matrix units in the first layer super surface 2, the second layer super surface 3 and the third layer super surface 4 can improve the matching degree with the optical fiber mode, thereby increasing the light coupling efficiency in the coupler and reducing the loss of the whole coupler.

And, the first layer surpasses surperficial 2, the second floor surpasses surperficial 3 and the third layer surpasses the matrix structure parameter form of surperficial 4 nimble, can satisfy multiple demand to form high performance multi-functional coupler structure, novel structure, the practicality is strong.

The light coupling device is convenient to design and simple to manufacture, can realize high-efficiency light coupling, and has a large coupling bandwidth. The super surface of application graphite alkene layer and three-layer and bottom substrate 8 are as the coupler main part, novel structure, excellent performance, and many cases coupling and correlation function can also be realized to this structure simultaneously, and the practicality is strong.

The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.