阅读说明：本技术 一种通过纳米剪纸形成偏振旋转器的制备方法 (Preparation method for forming polarization rotator through nano paper-cut ) 是由 李家方 刘之光 于 2018-06-14 设计创作，主要内容包括：本发明提供了一种通过纳米剪纸形成偏振旋转器的制备方法,属于三维微纳加工技术和三维器件技术领域。其包括步骤:制备一悬空的导电薄膜；对所述导电薄膜切割,得到至少一个导电薄膜构成局部连接的、多条非接触曲线构成的非封闭二维通透结构；采用离子束对非封闭二维通透结构所在的区域进行帧扫描式的整体辐照,以形成拱起及扭曲的三维曲面微纳结构,即得到构成偏振旋转器的三维曲面结构单元；将三维曲面结构单元按预定的周期排列,以得到偏振旋转器。本发明提供的制备方法,能解决现有技术中三维微纳结构形貌简单,无法实现丰富的三维微纳结构制备的不足,具有工艺简单、易于实现、可重复制作的优点。(The invention provides a preparation method for forming a polarization rotator through nano paper-cut, and belongs to the technical field of three-dimensional micro-nano processing technology and three-dimensional devices. The method comprises preparing a suspended conductive film; cutting the conductive film to obtain a non-closed two-dimensional transparent structure which is formed by a plurality of non-contact curves and is formed by at least one conductive film in a local connection manner; carrying out frame scanning type integral irradiation on the region where the non-closed two-dimensional transparent structure is located by adopting an ion beam to form an arched and distorted three-dimensional curved surface micro-nano structure, and obtaining a three-dimensional curved surface structure unit forming the polarization rotator; and arranging the three-dimensional curved surface structure units according to a preset period to obtain the polarization rotator. The preparation method provided by the invention can overcome the defects that the three-dimensional micro-nano structure in the prior art is simple in appearance and cannot realize rich preparation of the three-dimensional micro-nano structure, and has the advantages of simple process, easiness in realization and capability of being repeatedly manufactured.)

1. A method of making a polarization rotator formed by nano-paper-cut, comprising the steps of:

s1, preparing a suspended conductive film;

s2, cutting the conductive film to obtain a non-closed two-dimensional through structure which is formed by a plurality of non-contact curves and is formed by at least one conductive film in a local connection mode;

s3, performing frame scanning type integral irradiation on the region where the non-closed two-dimensional transparent structure is located by adopting ion beams to form an arched and twisted three-dimensional curved surface micro-nano structure, and obtaining a three-dimensional curved surface structure unit forming the polarization rotator;

and S4, arranging the three-dimensional curved surface structure units according to a preset period to obtain the polarization rotator.

2. The method according to claim 1, wherein the conductive film is a flat-surfaced, suspended-in-the-middle, peripherally-supported conductive film.

3. The manufacturing method according to claim 1 or 2, wherein a conductive film is formed in suspension on a substrate having a window, and the periphery of the conductive film is supported by the window of the substrate.

4. The production method according to claim 1, wherein the conductive film is a composite film or a pure metal film; the composite film is formed by performing metal coating on a dielectric film material; the pure metal film is obtained by removing the dielectric film by utilizing a micro-nano processing technology.

5. The method of claim 4, wherein the composite film is a gold-plated film thermally evaporated from a commercial silicon nitride window.

6. The method according to claim 4, wherein the conductive film is one or more of gold, silver, copper, aluminum, nickel, titanium, and chromium.

7. The method of claim 1, wherein the cutting of the conductive film in S2 is performed by ion beam cutting, uv exposure, or electron beam exposure and etching.

8. The method for preparing a three-dimensional device according to claim 1, wherein in S2, the shape of the non-closed two-dimensional through structure is selected according to the requirement of the final three-dimensional device;

the non-closed two-dimensional transparent structure can be any one of a four-leg windmill-shaped structure, a three-leg windmill-shaped structure and a composite arc-shaped structure.

9. The method of claim 1, wherein the three-dimensional curved micro-nano structure has a continuously varying curved surface and three-dimensional distortion characteristics in S3.

10. The preparation method according to claim 1, wherein in S3, the non-closed two-dimensional transparent structure is irradiated with ion beams to deform the area of the conductive film covered by the scanning, and the parts of the non-closed two-dimensional transparent structure are associated and interacted with each other while being deformed respectively, so as to drive the whole pattern to form distortion deformation while arching upwards, thereby realizing the step of drawing patterns of the nano paper-cut to form the suspended three-dimensional curved surface micro-nano structure with rich geometrical structure.

Technical Field

The invention relates to the technical field of three-dimensional micro-nano processing technology and three-dimensional devices, in particular to a preparation method for forming a polarization rotator through nano paper-cut.

Background

Light is an electromagnetic wave, and the polarization characteristic of the light is widely applied to the fields of 3D imaging and communication (particularly quantum communication). Traditional polarization rotators, such as liquid crystal and faraday rotators, are not favorable for the integrated application of micro-nano devices due to low polarization efficiency and large thickness.

On the other hand, with the integration degree of micro-nano photoelectric devices being higher and higher, the integration of the photoelectric devices in a two-dimensional space is difficult to meet the increasing multifunctional requirements, so that the preparation of the three-dimensional micro-nano photoelectric devices becomes an important way for the microminiaturization and functional integration development of the micro-nano devices, and a plurality of three-dimensional preparation technologies such as 3D printing are greatly concerned and developed. However, the preparation of micro-nano-scale metal photoelectric functional devices by 3D printing presents a great challenge. Meanwhile, simple processes for preparing three-dimensional structures by controlling the deformation of the thin film through ion beam irradiation have been developed. The specific principle is that a cantilever structure is etched on a suspended self-supporting metal film by using focused ion beams, and then the metal cantilever structure is deformed by using ion beam irradiation, so that some simple three-dimensional metal structures can be obtained. The three-dimensional metal structure has shown unique application value in the aspects of micro-nano optical property development, micro-nano optical sensing, photoelectric regulation and the like.

However, the three-dimensional micro-nano structure obtained in the prior art has a simple appearance, and cannot realize rich preparation of the three-dimensional micro-nano structure, such as a polarization rotator of a three-dimensional free-form surface, so that the application of the three-dimensional micro-nano structure in the wider micro-nano photoelectric field is limited.

Disclosure of Invention

The invention aims to provide a preparation method for forming a polarization rotator through nano paper-cut, overcomes the technical defects, and solves the defects that the three-dimensional micro-nano structure in the prior art is simple in appearance and cannot be prepared in a rich manner.

In particular, the present invention provides a method for manufacturing a polarization rotator formed by nano-paper-cut, comprising the steps of:

s1, preparing a suspended conductive film;

s2, cutting the conductive film to obtain a non-closed two-dimensional through structure which is formed by a plurality of non-contact curves and is formed by at least one conductive film in a local connection mode;

s3, performing frame scanning type integral irradiation on the region where the non-closed two-dimensional transparent structure is located by adopting ion beams to form an arched and twisted three-dimensional curved surface micro-nano structure, and obtaining a three-dimensional curved surface structure unit forming the polarization rotator;

and S4, arranging the three-dimensional curved surface structure units according to a preset period to obtain the polarization rotator.

Optionally, the conductive film is a conductive film with a flat surface, a suspended middle and a supported periphery.

Optionally, the conductive film is formed on a substrate with a window in a suspension manner, and the periphery of the conductive film is supported by the window of the substrate.

Optionally, the conductive film is a composite film or a pure metal film; the composite film is formed by performing metal coating on a dielectric film material; the pure metal film is obtained by removing the dielectric film by utilizing a micro-nano processing technology.

Optionally, the composite film is a gold-plated film thermally evaporated by a commercial silicon nitride window.

Optionally, the conductive film is one or more of gold, silver, copper, aluminum, nickel, titanium, and chromium.

Optionally, in S2, the cutting of the conductive film is performed by using an ion beam cutting, an ultraviolet exposure or an electron beam exposure and etching process.

Optionally, in S2, the shape of the non-closed two-dimensional through structure is selected according to the requirement of the final three-dimensional device;

the non-closed two-dimensional transparent structure can be any one of a four-leg windmill-shaped structure, a three-leg windmill-shaped structure and a composite arc-shaped structure.

Optionally, in S3, the three-dimensional curved micro-nano structure has a continuously changing curved surface and three-dimensional distortion characteristics.

Optionally, in S3, the non-closed two-dimensional transparent structure is irradiated with an ion beam to deform the conductive film region covered by the scanning, and the parts of the non-closed two-dimensional transparent structure are associated and interact with each other while deforming respectively, so as to drive the whole pattern to form a distortion while arching upwards, so as to realize a step of drawing patterns of the nano paper-cut, thereby forming a suspended three-dimensional curved surface micro-nano structure with rich geometric structures.

The invention provides a preparation method for forming a polarization rotator through nano paper-cut, and provides a processing method for forming a three-dimensional curved surface polarization rotator through implementing the nano paper-cut. The method is simple to operate, the traditional drawing and paper-cutting process is expanded to the field of micro-nano processing, the cutting is performed firstly, then the drawing is performed, all sub-components of the three-dimensional micro-nano device are related to each other, and the method belongs to a closed-loop preparation process, namely the richer and more complicated three-dimensional curved surface micro-nano structure device is realized through the stress balance formed by the closed loop.

Compared with the existing open-loop ion beam irradiation preparation technology, the preparation method for forming the polarization rotator through the nano paper-cut can repeatedly manufacture the three-dimensional curved surface polarization rotator which has rich and complex appearance and can not be realized by other micro-nano preparation methods through integral irradiation by using an easily-realized closed-loop process.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter, by way of illustration and not limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

FIG. 1 is a schematic diagram of a fabrication process for forming a polarization rotator by nano-paper-cut according to the present invention;

FIG. 2 is a schematic flow diagram of a method of making a polarization rotator formed by nano-paper-cut according to the present invention;

FIG. 3 is a schematic diagram illustrating the operation of a polarization rotator according to the present invention;

FIG. 4 is a schematic diagram of a fabrication process for forming a polarization rotator by nano-paper-cut according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a method for preparing a three-dimensional micro-nano structure according to another embodiment of the invention.

Detailed Description

The inventor of the present invention has conducted intensive research on a process for preparing a three-dimensional structure by controlling deformation of a thin film through ion beam irradiation in the prior art, and found that: in the prior art, the process for preparing the three-dimensional structure by controlling the deformation of the film through ion beam irradiation adopts a tree-shaped, namely open-loop, preparation process, and all substructures are linearly linked, so that the obtained three-dimensional micro-nano structure is simple in appearance, and cannot be prepared into abundant three-dimensional micro-nano structures, so that the three-dimensional micro-nano structure cannot be used for preparing a polarization rotator such as a three-dimensional free curved surface, and the application of the three-dimensional micro-nano structure in the wider micro-nano photoelectric field is limited.

Therefore, aiming at the discovery, a processing method for forming a three-dimensional curved surface polarization rotator by implementing nano paper-cut is provided, the traditional flower-drawing paper-cut process is expanded to the field of micro-nano processing, the sub-components of the three-dimensional micro-nano device are mutually associated after the cutting and the flower-drawing, and the method belongs to a closed-loop preparation process, namely, the richer and more complicated three-dimensional curved surface micro-nano structure device is realized by the stress balance formed by the closed loop.

Fig. 1 is a schematic diagram of a fabrication method of forming a polarization rotator by nano-paper-cut according to the present invention. Fig. 2 is a schematic flow diagram of a method of making a polarization rotator formed by nano-paper-cut according to the present invention. Fig. 3 is a schematic diagram illustrating the operation of a polarization rotator according to the present invention. Fig. 4 is a schematic diagram of a method of manufacturing a polarization rotator formed by nano-paper-cut according to an embodiment of the present invention. The following describes a method for manufacturing a polarization rotator formed by nano-paper-cut according to the present invention in detail with reference to fig. 1 to 4.

Specifically, the present invention provides a method for manufacturing a polarization rotator formed by nano-paper-cut, which generally comprises the following steps:

s1, preparing a suspended conductive film;

s2, cutting the conductive film to obtain a non-closed two-dimensional through structure which is formed by a plurality of non-contact curves and is formed by at least one conductive film in a local connection mode;

s3, performing frame scanning type integral irradiation on the region where the non-closed two-dimensional transparent structure is located by adopting ion beams to form an arched and twisted three-dimensional curved surface micro-nano structure, and obtaining a three-dimensional curved surface structure unit forming the polarization rotator;

and S4, arranging the three-dimensional curved surface structure units according to a preset period to obtain the polarization rotator.

Specifically, in S1, a suspended conductive film having a flat surface is provided as an object of the nano-cut paper. The conductive film 2 is a conductive film with a flat surface, a suspended middle and a supported periphery. As shown in fig. 1, a substrate 1 is covered with a conductive film 2. The conductive film 2 is formed on the substrate 1 with the window in a suspended manner, and four sides of the conductive film 2 are supported by the window of the substrate 1.

The suspended conductive film 2 supported by the window may be a composite film formed by metal plating a dielectric film material, such as a thermal evaporation gold plating film for a commercially available silicon nitride window, or a pure metal film obtained by removing the dielectric film by a micro-nano processing technique. In a specific embodiment, the conductive film 2 is one or more of gold, silver, copper, aluminum, nickel, titanium, and chromium.

At S2, a device cell having a predetermined pattern is formed by "trimming" on the conductive film 2 by ion beam cutting. The ion beam species may be a focused ion beam or a broad beam ion beam. The energy of the ions in the ion beam is greater than 500 electron volts. In other embodiments, a non-closed curve pattern may be obtained by using an ultraviolet exposure/electron beam exposure process, and the non-closed transparent structure 3 formed by a plurality of non-contact curves may be obtained by using an etching process. The non-closed through-structure 3 formed on the conductive film 2 layer shown in fig. 1 has a shape of a predetermined pattern of a four-legged windmill.

In a preferred embodiment of the present invention, the gold film is selected to have a thickness of 80 nm. If the thickness of the conductive film 2 is too large, the elastic stress of the film is too large to form a device. Conversely, if the thickness of the conductive film 2 is too small, the deformation is too large, deforming the device. The predetermined pattern (i.e., the shape of the non-closed two-dimensional through-structure 3) formed on the conductive film 2 is not limited to a four-leg windmill-shaped structure, and a desired shape may be selected according to the requirements for finally manufacturing a three-dimensional device. The predetermined pattern may be a three-legged windmill structure, a compound arc structure, or other shaped structure. And finally forming the three-dimensional curved surface micro-nano structure according to the difference of the appearances of the designed preset patterns, wherein the deformation directions are also different. For example, as shown in fig. 5, a micro-nano device with a net structure is formed on a suspended 80nm gold film, and the device is turned downwards from the plane of the film.

In S3, the ion beam is used to perform integral irradiation, i.e., frame scanning, on the non-closed two-dimensional transparent structure 3 formed in S2, so that the conductive film region covered by the scanning is deformed, and the parts of the non-closed two-dimensional transparent structure 3 are associated and interacted with each other while being deformed respectively, thereby driving the whole pattern to form distortion deformation while arching upwards, realizing the step of drawing patterns of the nano paper-cut, and forming the suspended three-dimensional curved surface micro-nano structure 4 with rich geometric structure. The invention also discloses a basic principle of the closed-loop nano paper-cut technology discovered by the inventor when the technology for preparing the three-dimensional structure by controlling the deformation of the film through the ion beam irradiation in the prior art is deeply researched. The three-dimensional curved surface micro-nano structure 4 has continuously changed curved surfaces and three-dimensional distortion characteristics, and can bring novel characteristics to micro-nano devices.

In S4, the polarization rotator 5 may be configured by arranging three-dimensional curved surface structure units formed by the three-dimensional curved surface micro-nano structures 4 at a predetermined period. I.e. the polarization direction of the incident electromagnetic wave is rotated by an angle after passing through the polarization rotator 5. As shown in fig. 3, 11 is the polarization direction of incident light, 12 is the polarization rotation angle, 13 is the polarization direction of outgoing light, and 14 is the propagation direction of light.

In S4, the three-dimensional curved surface structure units formed by the three-dimensional curved surface micro-nano structures 4 are arranged according to a certain period, that is, the non-closed two-dimensional transparent structures 3 arranged according to a certain period are cut on the suspended conductive film 2 in S2, and then the non-closed two-dimensional transparent structures 3 arranged according to a certain period are subjected to integral irradiation deformation, so that the three-dimensional curved surface micro-nano structures 4 arranged according to a certain period are directly formed, and the three-dimensional curved surface polarization rotator 5 of the present invention is prepared. When the non-closed two-dimensional transparent structure 3 is subjected to integral irradiation deformation, the ion beam irradiates the whole conductive film 2 of the formed non-closed two-dimensional transparent structure 3, and under the action of ion beam irradiation, the non-closed two-dimensional transparent structure 3 is mutually associated and interacted while deforming respectively due to stress and local connection of the non-closed two-dimensional transparent structure 3 and limitation of shapes caused by a plurality of non-contact curves, so that the whole pattern is driven to form distortion deformation while arching upwards, and the step of drawing patterns of nano paper-cut is realized, thereby forming a suspended three-dimensional curved surface micro-nano structure 4 with rich geometric structures, and the method is not like the method for preparing a simple three-dimensional metal structure in the prior art, and controls the deformation of each part of the metal cantilever structure respectively by adopting local ion beam irradiation with variable strength. In one particular embodiment, the suspended conductive film 2 supported by the window is a pure metal film. In other embodiments, not shown, the suspended conductive film 2 may also be a composite film formed by metal plating a dielectric film material, such as a thermal evaporation gold plating of a commercially available silicon nitride window.

Compared with the existing open-loop ion beam irradiation preparation technology, the preparation method for forming the polarization rotator through the nano paper-cut can repeatedly manufacture the three-dimensional curved surface polarization rotator which has rich and complex appearance and can not be realized by other micro-nano preparation methods through integral irradiation by using an easily-realized closed-loop process. The polarization rotator 5 works in an optical communication waveband of 1.5 microns, has the thickness of only 400-500 nm, has the deflection efficiency of 200,000 degrees/mm, and is an ultrathin polarization rotator.

The invention provides a preparation method for forming a polarization rotator through nano paper-cut, and provides a processing method for forming a three-dimensional curved surface polarization rotator through implementing the nano paper-cut. The method is simple to operate, the traditional drawing and paper-cutting process is expanded to the field of micro-nano processing, the cutting is performed firstly, then the drawing is performed, all sub-components of the three-dimensional micro-nano device are related to each other, and the method belongs to a closed-loop preparation process, namely the richer and more complicated three-dimensional curved surface micro-nano structure device is realized through the stress balance formed by the closed loop.

Compared with the existing open-loop ion beam irradiation preparation technology, the preparation method for forming the polarization rotator through the nano paper-cut can repeatedly manufacture the three-dimensional curved surface polarization rotator which has rich and complex appearance and can not be realized by other micro-nano preparation methods through integral irradiation by using an easily-realized closed-loop process.

The following is a detailed description with reference to more specific examples.

Step 1: a layer of ultraviolet photoresist S1813 is spin-coated on a silicon substrate with the thickness of 500 microns at the rotation speed of 4000 r/min, and then the silicon substrate is placed on a hot plate at the temperature of 115 ℃ and baked for 2 minutes to volatilize the solvent.

Step 2: and depositing a gold film layer with the thickness of 80 nanometers on the silicon substrate coated with the photoresist through electron beam evaporation.

And step 3: the substrate with the 80 nanometer gold film is soaked in acetone for 24 hours, so that the photoresist S1813 is fully dissolved, and the gold film falls off from the surface of the silicon substrate and floats in the acetone solution.

And 4, step 4: and clamping a commercial TEM grid by using tweezers, taking out the gold film floating in the solution, and drying the gold film in a nitrogen environment to obtain the suspended conductive film 2.

And 5: and 4, cutting a plurality of non-closed non-contact curve through structures with preset patterns on the suspended conductive film 2 obtained in the step 4 by using focused ion beams. The ion species being Ga⁺The accelerating voltage is 30kV, the ion beam current is 24pA, and the scanning dose is 600 pC/mum²。

Step 6: and (3) carrying out integral frame scanning on the suspended non-closed curve transparent structure obtained in the step (5) by utilizing a focused ion beam, wherein the suspended structure is arched upwards, and meanwhile, the suspended structure is distorted due to interaction among the substructures, so that a final suspended three-dimensional curved surface micro-nano structure 4 is formed. The ion beam current is 24pA, and the scanning dose is 40 pC/mum²。

In the above step 5, a plurality of device units may be formed on the conductive film 2, that is, a three-dimensional curved-surface polarization rotator array may be formed on the surface of the conductive film 2 by the plurality of device units. FIG. 4 is a scanning electron micrograph of a polarization rotator formed on a suspended 80nm gold film. When the size of the structural unit is 1.1 micron, the height is 380nm, and the period is 1.45 microns, the experiment shows that the angle of polarization rotation at 1.7 microns reaches 90 degrees, and the polarization rotation efficiency reaches 200000 degrees/mm.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.