阅读说明：本技术 一种电磁超表面、其制备方法及纳米宽带陷波滤波器 (Electromagnetic super-surface, preparation method thereof and nano broadband notch filter ) 是由 黄姗 童志崇 俞挺 邹成武 于 2020-11-30 设计创作，主要内容包括：本发明涉及电磁超表面领域,尤其涉及一种电磁超表面、其制备方法及纳米宽带陷波滤波器。其中,电磁超表面包括第一金属层、第二金属层和介质层,所述第一金属层包括多个阵列排布的第一纳米单元结构,所述第二金属层包括多个阵列排布的第二纳米单元结构,至少部分所述介质层位于所述第一金属层和第二金属层之间。本发明所提出的电磁超表面结合传统光学的透射途径和表面等离激元滤波特性,可以实现宽带滤波的效果。(The invention relates to the field of electromagnetic super surfaces, in particular to an electromagnetic super surface, a preparation method thereof and a nano broadband notch filter. The electromagnetic super-surface comprises a first metal layer, a second metal layer and a dielectric layer, wherein the first metal layer comprises a plurality of first nano unit structures arranged in an array, the second metal layer comprises a plurality of second nano unit structures arranged in an array, and at least part of the dielectric layer is positioned between the first metal layer and the second metal layer. The electromagnetic super-surface provided by the invention can realize the effect of broadband filtering by combining the transmission path of the traditional optics and the surface plasmon filtering characteristic.)

1. An electromagnetic super-surface comprises a first metal layer, a second metal layer and a dielectric layer, and is characterized in that: the first metal layer comprises a plurality of first nano unit structures arranged in an array, the second metal layer comprises a plurality of second nano unit structures arranged in an array, and at least part of the dielectric layer is positioned between the first metal layer and the second metal layer.

2. An electromagnetic super-surface according to claim 1, comprising: at least one section of the first nanometer unit structure and the second nanometer unit structure is square, and the side length of the square is 50-200 nm.

3. An electromagnetic super-surface according to claim 1, comprising: the first and second nano-unit structures have a thickness of 50-100 nm.

4. An electromagnetic super-surface according to any of claims 1-3, comprising: the material of the first metal layer and the second metal layer is at least one selected from gold or silver.

5. A method for preparing an electromagnetic super-surface is characterized by comprising the following steps:

preparing a first metal layer, wherein the first metal layer comprises a plurality of first nano unit structures arranged in an array;

preparing a dielectric layer on the first metal layer;

and preparing a second metal layer on the dielectric layer, wherein the second metal layer comprises a plurality of second nanometer unit structures which are arranged in an array.

6. A method for preparing an electromagnetic super-surface according to claim 5, wherein the preparing a first metal layer comprising a plurality of first nano-unit structures arranged in an array comprises:

providing a first substrate;

forming a first layer of polymeric material on the first substrate;

patterning the first polymer material layer to obtain first patterns, wherein first nanogaps are arranged among the first patterns;

forming a first metal material layer on the first pattern and the first nanogap;

and removing the first pattern and the first metal material layer positioned on the first pattern to obtain a first metal layer.

7. The method for preparing an electromagnetic super-surface according to claim 6, wherein the preparing a second metal layer on the dielectric layer, the second metal layer comprising a plurality of second nano-unit structures arranged in an array, comprises:

forming a second polymer material layer on the dielectric layer;

patterning the second polymer material layer to obtain second patterns, wherein second nanogaps are arranged between the second patterns;

forming a second metal material layer on the second pattern and the second nanogap;

and removing the second pattern and the second metal material layer positioned on the second pattern to obtain a second metal layer.

8. A method for preparing an electromagnetic super-surface according to any of claims 5 to 7, comprising: at least one section of the first nanometer unit structure and the second nanometer unit structure is square, and the side length of the square is 50-200 nm.

9. A method for preparing an electromagnetic super-surface according to any of claims 5 to 7, comprising: the first and second nano-unit structures have a thickness of 50-100 nm.

10. A nanometer broadband notch filter, includes electromagnetism super surface, its characterized in that: the electromagnetic super surface is as defined in any one of claims 1 to 4.

Technical Field

The invention relates to the field of electromagnetic super surfaces, in particular to an electromagnetic super surface, a preparation method thereof and a nano broadband notch filter.

Background

Surface plasmons (plasmonics) are an electromagnetic vibration mode bound to a metal/dielectric interface, and are characterized in that an electric field is exponentially attenuated along a direction perpendicular to the interface, and has a longer propagation length along the metal/dielectric interface. The unique physical characteristics of the surface plasmon can control light in micron and even nanometer scale, and the diffraction limit of the traditional optics is broken through. Therefore, the optical functional device based on the surface plasmon has a wide prospect in miniaturization of optical devices.

The main principle of the existing filter based on the surface plasmon is to utilize the coupling of incident light and a metal structure to excite a surface plasmon resonance mode to realize the absorption or the super transmission of specific frequency. In recent years, researchers propose and develop various different surface plasmon filtering systems, and based on a periodic metal nanopore array of a surface plasmon patch wave, the filtering frequency can be modulated by changing the period; the multilayer nano-film based on Fabry-Perot resonance can modulate the filtering frequency and the filtering quality by changing the thickness.

Electromagnetic super-surface (also called super-surface) refers to an artificial layered material with a thickness smaller than the wavelength. The super surface can realize flexible and effective regulation and control of electromagnetic wave phase, polarization mode, propagation mode and other characteristics. Novel physical effects such as negative refraction, negative reflection, polarization rotation, convergent imaging, complex wave beams, conversion from propagating waves to surface waves and the like can be realized through the super surface. The super-surface has abundant and unique physical characteristics and flexible regulation and control capability on electromagnetic waves, so that the super-surface has important application prospects in various fields such as stealth technology, antenna technology, microwave and terahertz devices, optoelectronic devices and the like. In recent years, researchers have designed super-surface structures, and multi-frequency band-pass filtering can be realized by utilizing multi-order local surface plasmon resonance modes in metal structures. The super-surface of the metal-medium-metal three-layer structure consumes the corresponding frequency light field energy by utilizing the ohmic loss of electromagnetic field resonance between the upper layer metal structure and the lower layer metal structure, realizes the near-complete absorption of incident light and obtains the trap filter performance with better quality.

The filter based on the super-surface structure has the advantages of miniaturization, good wavelength blocking performance, flexible frequency band regulation and control and the like. However, since the surface plasmon resonance mode is excited only when a specific frequency matching condition is satisfied, the filter based on the surface plasmon resonance alone has a characteristic of a narrow operating band, which is not favorable for realizing a broadband filtering performance. The surface plasmon notch filter disclosed in the prior art, although the surface plasmon filtering is realized by using the wavelength selectivity of the dielectric cavity resonance, has a stop band width (half width) of only 30-58 nm. How to construct a broadband filter based on a super surface is still a scientific and technical bottleneck faced by researchers at home and abroad currently.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present application aims to provide an electromagnetic super-surface, a method for manufacturing the same, and a nano broadband notch filter, which are intended to solve the problems in the prior art.

The invention provides an electromagnetic super-surface, which comprises a first metal layer, a second metal layer and a dielectric layer, wherein the first metal layer comprises a plurality of first nano unit structures arranged in an array, the second metal layer comprises a plurality of second nano unit structures arranged in an array, and at least part of the dielectric layer is positioned between the first metal layer and the second metal layer. The electromagnetic super-surface provided by the invention combines the transmission path and the surface plasmon filtering characteristic of the traditional optics, the plasmon resonance metal structure arrays on the upper and lower layers of surfaces form resonance cavity oscillation, the optical field energy is consumed through ohmic loss, and finally the filtering with transmission almost equal to zero is realized, and the broadband filtering effect can be realized.

Optionally, at least one of the first and second nano-cell structures has a square cross-section with a side length of 50-200 nm. The unit structure is a non-special-shaped structure and is convenient to realize.

Optionally, the first and second nano-cell structures have a thickness of 50-100 nm. The filtering precision can be effectively improved by arranging the nanoscale unit structures on the first metal layer and the second metal layer.

Optionally, the material of the first metal layer and the second metal layer is selected from at least one of gold or silver.

The second aspect of the invention provides a method for preparing an electromagnetic super-surface, which comprises the following steps: preparing a first metal layer, wherein the first metal layer comprises a plurality of first nano unit structures arranged in an array; preparing a dielectric layer on the first metal layer; and preparing a second metal layer on the dielectric layer, wherein the second metal layer comprises a plurality of second nanometer unit structures which are arranged in an array. The preparation method is simple and convenient for industrial application.

Optionally, the preparing a first metal layer, where the first metal layer includes a plurality of first nano unit structures arranged in an array, includes: providing a first substrate; forming a first layer of polymeric material on the first substrate; patterning the first polymer material layer to obtain first patterns, wherein first nanogaps are arranged among the first patterns; forming a first metal material layer on the first pattern and the first nanogap; and removing the first pattern and the first metal material layer positioned on the first pattern to obtain a first metal layer. The process and the technology are mature and easy to realize.

Optionally, the preparing a second metal layer on the dielectric layer, where the second metal layer includes a plurality of second nano unit structures arranged in an array, includes: forming a second polymer material layer on the dielectric layer; patterning the second polymer material layer to obtain second patterns, wherein second nanogaps are arranged between the second patterns; forming a second metal material layer on the second pattern and the second nanogap; and removing the second pattern and the second metal material layer positioned on the second pattern to obtain a second metal layer. The process and the technology are mature and easy to realize.

Optionally, at least one of the first and second nano-cell structures has a square cross-section with a side length of 50-200 nm.

Optionally, the first and second nano-cell structures have a thickness of 50-100 nm.

A third aspect of the invention provides a nano broadband notch filter comprising an electromagnetic super-surface as described in the first aspect of the invention. The nano broadband notch filter provided by the invention combines the transmission path and the surface plasmon filtering characteristic of the traditional optics. The light is directly transmitted by using the penetration effect of the light in a short wave band. In the long wavelength band, the diffraction effect of light is stronger and can penetrate from the gap of the nano unit structure in a diffraction mode. And in a trap wave band, after the surface plasmon resonance mode is excited by optical coupling, the resonant cavity formed by the upper layer surface plasmon resonance nanometer unit structure array and the lower layer surface plasmon resonance nanometer unit structure array vibrates, the energy of a light field is consumed through ohmic loss, and finally filtering with transmission being almost zero is realized.

Drawings

FIG. 1 is a schematic view of one embodiment of an electromagnetic super-surface of the present invention;

FIG. 2 is a schematic view of another embodiment of an electromagnetic meta-surface of the present invention;

FIG. 3 is an electron micrograph of an embodiment of a first metal layer or a second metal layer of the present invention;

FIG. 4 is a flow chart of an embodiment of a method of making an electromagnetic super-surface of the present invention;

FIG. 5 is a schematic view of an embodiment of the present invention for forming a first metal layer;

FIG. 6 is a schematic view of an embodiment of the present invention for forming a second metal layer;

FIG. 7 is an intensity transmission spectrum of an embodiment of the present invention after a surface plasmon passes through a nano broadband notch filter.

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

Specific embodiments of the present invention will be described in detail below, and it should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known circuits, software, or methods have not been described in detail so as not to obscure the present invention.

Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale.

The problems of the existing scheme are as follows: in the prior art, the filter based on the super-surface structure has the advantages of miniaturization, good wavelength blocking performance, flexible frequency band regulation and control and the like. However, since the surface plasmon resonance mode is excited only when a specific frequency matching condition is satisfied, the filter based on the surface plasmon resonance alone has a characteristic of a narrow operating band, which is not favorable for realizing a broadband filtering performance.

Based on this, the present application intends to provide a solution to the above technical problem, the details of which will be explained in the following embodiments.

The scheme of the application elaborates an electromagnetic super-surface, which comprises a first metal layer 1, a dielectric layer 2 and a second metal layer 3. The first metal layer 1 includes a plurality of first nano-cell structures 101 arranged in an array, and the second metal layer 3 includes a plurality of second nano-cell structures 301 arranged in an array. The first metal layer 1 and the second metal layer 3 are made of gold. In another embodiment, the material of the first metal layer 1 and the second metal layer 3 is silver, and in other embodiments, the material of the first metal layer 1 and the second metal layer 3 may also be a combination of gold and silver. The gold or silver is adopted as the material of the first metal layer 1 and the second metal layer 3, so that the precision of notch filtering can be effectively improved. The dielectric layer 2 is made of silicon dioxide. In another embodiment, the layer may also be alumina. In other embodiments, the material of the dielectric layer 2 may also be selected from other transparent materials, which are not listed here.

Referring to fig. 1, in an embodiment, a portion of the dielectric layer 2 is located between the first metal layer 1 and the second metal layer 3, that is, the first nano-cell structures 101 constituting the first metal layer 1 are all embedded in one side of the dielectric layer 2, and the second nano-cell structures 301 constituting the second metal layer 3 are all embedded in the other side of the dielectric layer 2.

Referring to fig. 2, in another embodiment, the dielectric layer 2 is located between the first metal layer 1 and the second metal layer 3, that is, the first nano-cell structures 101 constituting the first metal layer 1 are all located on one side surface of the dielectric layer 2, and the second nano-cell structures 301 constituting the second metal layer 3 are all located on the other side surface of the dielectric layer 2.

Referring to fig. 3, at least one of the cross sections of the first nano cell structure 101 and the second nano cell structure 301 is square, and the side length of the square is 50-200 nm. In another embodiment, at least one of the cross-sections of the first nano-cell structure 101 and the second nano-cell structure 301 is rectangular. The first 101 and second 301 nano-cell structures have a thickness of 50-100 nm. Wherein the first nano-cell structure 101 and the second nano-cell structure 301 are periodically arranged in a square array, and further, the arrangement period of the square array is 100-400 nm. In another embodiment, the first nano-cell structure 101 and the second nano-cell structure 301 are also periodically arranged in a rectangular array.

Referring to fig. 4, the present application describes in detail a method for preparing an electromagnetic super-surface, including:

s1, preparing a first metal layer 1, where the first metal layer 1 includes a plurality of first nano-cell structures 101 arranged in an array, referring to fig. 5, which specifically includes:

a first substrate 4 is provided.

The first substrate 4 has at least one flat surface, and the material of the first substrate 4 may include, but is not limited to, silicon dioxide.

A first layer of polymer material 5 is formed on the flat surface of the first substrate 4.

The material of the first polymer material layer 5 may be PMMA photoresist or photoresist, and the photoresist may be negative photoresist or positive photoresist. In the preparation process, the PMMA photoresist or the photoresist can be formed on the flat surface by spin coating, and the thickness of the PMMA photoresist or the photoresist can be selected according to the actual requirement, which is not limited herein.

The first layer of polymer material 5 is patterned to form a plurality of first patterns 501, with a first nanogap 502 between two adjacent first patterns 501.

The patterning of the first polymer material layer 5 may be employed including, but not limited to: electron beam lithography, nanoimprint lithography, interference lithography, phase separation, self-assembly, and the like.

In one embodiment, patterning said first layer of polymer material 5 comprises in particular: providing a first mask plate, wherein the first mask plate is provided with a plurality of through holes. A first light emitting device is provided, which may be various light sources having UV light that may be irradiated on the first polymer material layer 5 through the through-holes of the first mask. After the UV light is irradiated to the first polymer material layer 5, a post-exposure baking process may be performed, so as to improve the difference between the physical properties of the exposed portion and the unexposed portion of the first polymer material layer 5, and further improve the yield of the subsequent developing process. And then the developing manufacturing process is carried out. In one embodiment, if the material of the first polymer material layer 5 is a positive photoresist, the portion of the first polymer material layer 5 irradiated by the UV light will undergo a cleavage reaction and become a portion with a lower degree of cross-linking. After the development process, the portions not exposed to the UV light remain, and the portions exposed to the UV light are washed away. In other embodiments, a negative photoresist may be used as the first polymer material layer 5, and a portion of the first polymer material layer 5 irradiated by the UV light may generate a cross-linking reaction to become a portion with a higher degree of cross-linking. After the development process, the portion having a high degree of crosslinking remains, and the portion having a low degree of crosslinking is washed away.

A first metallic material layer is formed on the first pattern 501 and the first nanogap 502.

Wherein, a metal film with a nanometer-scale thickness can be deposited on the first pattern 501 and the first nanogap 502 by a thin film deposition technique, such as but not limited to an electron beam evaporation deposition technique, a spin coating technique, an ion sputtering thin film deposition technique, an atomic layer thin film deposition technique, a self-assembly technique, and the like, to form the first metal material layer.

And removing the first pattern 501 and the first metal material layer on the first pattern 501 to obtain a first metal layer 1.

Wherein the first pattern 501 and the first metallic material layer on the first pattern 501 may be removed by an etching technique. In some embodiments, the etching solution may be a plurality of etching solutions, and is not limited herein; and removing the residual part of the first polymer material layer 5 by using acetone or oxygen plasma, and finally obtaining the first metal layer 1 consisting of the first nano unit structure 101 array.

And S2, preparing a dielectric layer 2 on the first metal layer 1.

In one embodiment, a transparent dielectric layer 2 with a thickness of nanometer order may be deposited on the first metal layer 1 by using a thin film deposition technique, but not limited to, the material of the dielectric layer 2 is silicon dioxide. In another embodiment, the dielectric layer 2 may also be alumina. In other embodiments, the material of the dielectric layer 2 may also be selected from other transparent materials, which are not listed here.

S3, preparing a second metal layer 3 on the dielectric layer 2, where the second metal layer 3 includes a plurality of second nano-unit structures 301 arranged in an array, with reference to fig. 6, which specifically includes:

a second layer of polymer material 6 is formed on the dielectric layer 2.

The second polymer material layer 6 is patterned to obtain second patterns 601, and second nanogaps 602 are formed between the second patterns 601.

A second metallic material layer is formed on the second pattern 601 and the second nanogap 602.

And removing the second pattern 601 and the second metal material layer on the second pattern 601 to obtain a second metal layer 3.

For the specific material of the second polymer material layer 6, the patterning process thereof, and the preparation of the second metal layer 3, reference may be made to the processing manner of the first polymer material layer 5 in step S1.

In one embodiment, a lift-off step of the first substrate 4 may also be performed after the completion of the above-described electromagnetic super-surface preparation. In another embodiment, the first substrate 4 may not perform a lift-off step, and elements such as a nanobelt notch filter may be formed by directly fabricating other structures on the super-surface.

It should be noted that, for other structural features, beneficial effects and functions of the electromagnetic super surface, which are not mentioned in the related embodiments of the method for preparing the electromagnetic super surface, reference may be made to the related embodiments of the electromagnetic super surface, and details are not described herein.

The scheme of the application elaborates a nano broadband notch filter, which comprises an electromagnetic super surface, wherein the electromagnetic super surface and a preparation process thereof can be specifically referred to the relevant description of the electromagnetic super surface, and the description is brief for the implementation and will not be repeated. Referring to fig. 7, fig. 7 is a transmission spectrum of intensity (electric field square) of a numerically simulated surface plasmon after passing through a filter, and the abscissa is an incident vacuum wavelength. In the wave band from 563nm to 664nm, the transmittance is less than 0.01, namely, broadband notch filtering is realized. The stop band width (half width) was 150 nm. In addition, in an actual application process, filtering other bands may also be achieved by modulating the size of the first nano unit structure 101 and/or the second nano unit structure 301, which is not listed here.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.