Preparation method of metal chiral nano array based on thermal mechanical deformation and application of metal chiral nano array in chiral optical device

Abstract

The invention provides a preparation method of a metal chiral nano array based on thermal mechanical deformation and application of the metal chiral nano array in chiral optical devices, and belongs to the technical field of nano manufacturing. The directional shearing force is applied to the exposed metal nano array by utilizing the shearing force generated by the flowing of the high-viscosity fluid, so that the metal nano array is bent along the flowing direction, and the configuration of the metal nano array is regulated and controlled by regulating and controlling the length of the exposed metal nano array and the direction of the directional shearing force; therefore, the three-dimensional metal chiral nano array with high forming precision and surface integrity is prepared, and the problems that in the prior art, the internal porosity of a metal microstructure is high, the surface roughness is large, and the efficiency is low are solved. The prepared metal chiral nano array has excellent optical chiral characteristics, the bending direction of the metal chiral nano array determines the chiral characteristics, the reflection asymmetry factor is adjustable within 0.1-0.5, the light-emitting asymmetry factor can reach 0.3, and the metal chiral nano array has good application prospects in the field of precise optical devices.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-manufacturing, and in particular to a preparation method of a metal chiral nano-array based on thermomechanical deformation and an application thereof in chiral optical devices. Background Art

[0002] Three-dimensional metal microstructures have received extensive attention in the field of metamaterials in recent years due to their significant light-matter interaction enhancement properties in optical resonance systems. In particular, three-dimensional metal microstructures with spatial chirality have become an important direction for the research and development of advanced photonic devices because they can produce unique circular dichroism effects and strong chiral optical responses. It is worth pointing out that the realization of these chiral optical properties essentially depends on the forming accuracy and surface integrity of three-dimensional metal microstructures, which places stringent requirements on micro-nano processing technology.

[0003] The current mainstream preparation methods mainly include wet chemical synthesis, oblique deposition technology, and a composite process of laser direct writing combined with electrochemical deposition. However, wet chemical synthesis will inevitably introduce surfactant residues during the self-assembly process, resulting in organic pollutants adhering to the sample; oblique deposition technology often cannot avoid surface roughening; and although laser direct writing assisted electrochemical deposition process can achieve higher resolution, it requires exposure one by one and has low efficiency. The metal microstructures prepared by the above methods often have technical defects such as high internal porosity, large surface roughness or low efficiency, which seriously restricts the application of metal microstructures in precision optical devices.

[0004] Therefore, developing a method for preparing metal microstructures that can achieve high-precision three-dimensional forming, low defect density and atomic-level surface finish has become a key technical problem that needs to be urgently solved in this field. Summary of the invention

[0005] In view of the above shortcomings of the prior art, the present invention provides a method for preparing high-quality metal chiral nanostructure arrays based on thermomechanical deformation and its application in chiral optical devices. The present invention uses rheological shear force to orderly bend the single-crystal metal nanoarray prepared by thermomechanical deformation to achieve the preparation of a three-dimensional metal chiral nanostructure array, solving the problems of high internal porosity, large surface roughness, and low efficiency of the metal microstructure in the prior art.

[0006] To achieve the above purpose, the specific technical solutions of the present invention are as follows:

[0007] In a first aspect, the present invention provides a method for controlling the configuration of a large-area metal nanoarray using rheological shear force, comprising the following steps:

[0008] S1. Place the high-viscosity fluid material above the metal nanoarray and to one side, subject the high-viscosity fluid material to rheology under hot pressing conditions, and apply a directional shear force to the metal nanoarray in contact therewith using the shear force generated by the flow of the high-viscosity fluid material, so that the metal nanoarray bends along the flow direction;

[0009] S2. Use an etching solution to remove the high-viscosity fluid material on the surface of the metal nanoarray;

[0010] S3. Repeat steps S1 and S2, and realize the configuration regulation of the metal nanoarray by regulating the part in contact with the high-viscosity fluid material and the direction of the directional shear force.

[0011] Preferably, the high-viscosity fluid material includes but is not limited to glass or thermoplastic polymer, and the temperature at which the high-viscosity fluid material undergoes rheology is lower than the melting point of the metal nanoarray.

[0012] Preferably, when the high-viscosity fluid material is glass (such as Schott P-PK53), the hot pressing conditions are: temperature is 450 - 500 °C, axial pressure is 0.5 - 2 kN, and the holding time is 20 - 200 s; when the high-viscosity fluid material is thermoplastic polymer (such as PMMA), the hot pressing conditions are: temperature is 130 - 160 °C, axial pressure is 0.5 - 2 kN, and the holding time is 20 - 200 s.

[0013] Preferably, when the high-viscosity fluid material is glass, the etching solution is a mixed solution of 5wt% - 7wt% phosphoric acid and 1.5wt% - 2wt% chromic acid; when the high-viscosity fluid material is thermoplastic polymer, the etching solution is acetone.

[0014] In a second aspect, the present invention provides a method for preparing a metal chiral nanoarray based on thermomechanical deformation and the above method, including the following steps:

[0015] (1) Stack a metal sheet on a template with an ordered nanoporous structure, extrude the metal under hot pressing conditions to make it rheologically enter the nanopores of the template, and form an ordered metal nanoarray in the template;

[0016] (2) Immerse the ordered metal nanoarray in the template in an etching solution for treatment, corrode the surface layer of the template, so that a certain length of the ordered metal nanoarray in the template is exposed;

[0017] (3) Apply a directional shear force to the exposed ordered metal nanoarray using the shear force generated by the flow of the high-viscosity fluid material, so that the ordered metal nanoarray bends along the flow direction;

[0018] (4) Repeat steps (2) and (3) to achieve the configuration regulation of the metal nanoarray by controlling the exposure length of the ordered metal nanoarray and the direction of the directional shear force, and obtain a metal chiral nanoarray.

[0019] The technical principle of the present invention is as follows: In a template with an ordered nanoporous structure, the etching rate from the inside of the pore to the outside is the fastest. After undergoing a thermomechanical deformation process, the metal completely fills the nanopores of the template, forming an ordered metal nanoarray within the template. Therefore, the corrosion process in the etching solution will occur at the interface of the etching solution, the inner side of the template nanopores, and the ordered metal nanoarray, thereby realizing the ordered demolding of the ordered metal nanoarray from the head to the root.

[0020] Preferably, the metal material of the metal sheet in step (1) is gold, silver, aluminum, platinum, copper, or an alloy containing at least one of gold, silver, aluminum, platinum, and copper.

[0021] Preferably, the template in step (1) includes, but is not limited to, an alumina (AAO) template or a silicon template.

[0022] Preferably, the etching solution in step (2) is a mixed solution of 5wt% - 7wt% phosphoric acid and 1.5wt% - 2wt% chromic acid.

[0023] Preferably, the temperature of the ordered metal nanoarray treated in the etching solution in step (2) ≤ 60 °C, and the exposure length of the ordered metal nanoarray is regulated by controlling the treatment time of the ordered metal nanoarray in the etching solution.

[0024] Preferably, the metal chiral nanoarray is arranged in a periodic or quasi-periodic array form, and the array period ranges from 60 to 1000 nm.

[0025] Preferably, the metal chiral nanoarray has excellent optical chiral properties, its bending direction determines the chiral characteristics, and the reflection asymmetry factor is adjustable within 0.1 - 0.5.

[0026] In the third aspect, the present invention provides a metal chiral nanoarray prepared by using the above method.

[0027] In the fourth aspect, the present invention provides the application of the metal chiral nanoarray in circularly polarized luminescence, chiral molecule sensing, optical imaging, information storage, photoelectric detection, or flexible wearable devices.

[0028] Compared with the prior art, the advantages of the present invention are as follows:

[0029] The present invention utilizes the shear force generated by the flow of a highly viscous fluid to apply a directional shear force to the exposed metal nanoarray, causing the metal nanoarray to bend along the flow direction. By regulating the length of the exposed metal nanoarray and the strength / direction of the directional shear force, the configuration of the metal nanoarray is regulated, thereby preparing a three-dimensional metal chiral nanoarray with high forming accuracy and surface integrity, solving the problems of high internal porosity, large surface roughness, and low efficiency in the prior art. The metal chiral nanoarray prepared by the present invention has excellent optical chiral properties, and its bending direction determines the chiral characteristics, and the reflection asymmetry factor is adjustable in the range of 0.1 to 0.5, and the luminescence asymmetry factor can reach 0.3, having good application prospects in the field of precision optical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a schematic diagram of the preparation process of the metal chiral nanoarray;

[0031] Figure 2 FIG. is a schematic diagram of the thermomechanical deformation of an ordered nanoporous mold and a material to be thermoformed; wherein: 1. hot pressing plate; 2. metal material to be thermoformed; 3. nanoporous mold (AAO);

[0032] Figure 3 FIG. is a scanning electron microscope (SEM) image of the nanoarray with the head exposed; wherein, 3a is a top view; 3b is an oblique view;

[0033] Figure 4 FIG. is a schematic diagram of a glass rheological shear nanostructure; in the figure: 1. Schott P-PK53 type low melting point glass; 2. AAO; 3. nanostructure array with the head exposed;

[0034] Figure 5 FIG. is an oblique SEM view of the nanostructure array with different bending times. Among them, 5a is the nanostructure array without bending; 5b is the nanostructure array bent once; 5c and 5d are the nanostructure arrays bent twice and are enantiomers of each other;

[0035] Figure 6 FIG. is a schematic diagram of the preparation process of the metal chiral nanoarray; wherein: 1. AAO; 2. metal material to be thermoformed; 3. schematic diagram of the head exposure of the metal nanoarray; 4. schematic diagram of the metal nanoarray bent once; 5. schematic diagram of the metal nanoarray bent twice;

[0036] Figure 7 FIG. shows three typical cases of poor quality of the metal nanoarray; wherein, 7a is an oblique view of the non-uniform bending of the nanowires due to their different thicknesses; 7b and 7c are top views of the nanowires with incomplete bending and excessive bending and fracture respectively due to improper force or temperature conditions;

[0037] Figure 8 Reflection spectrum of circularly polarized light by a metal chiral nanostructure array;

[0038] Figure 9 Reflection circular dichroism spectrum of a metal chiral nanostructure array;

[0039] Figure 10 Schematic process diagram for fabricating a circularly polarized light emitting device based on left- and right-handed metal nanostructure arrays;

[0040] Figure 11 a, Figure 11 b, and Figure 11 c are diagrams of the right-handed circularly polarized light emission intensity, left-handed circularly polarized light emission intensity, and emission asymmetry factor of the circularly polarized light emitting device, respectively. Detailed implementation manners

[0041] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0042] The present invention provides a method for regulating the configuration of a large-area metal nanoarray by using rheological shear force, including the following steps:

[0043] S1. Place a high-viscosity fluid material above the metal nanoarray and bias it to one side. Under hot pressing conditions, make the high-viscosity fluid material undergo rheology, and use the shear force generated by the flow of the high-viscosity fluid to apply a directional shear force to the metal nanoarray, so that the metal nanoarray bends along the flow direction;

[0044] S2. Use an etching solution to remove the high-viscosity fluid material on the surface of the metal nanoarray;

[0045] S3. Repeat steps S1 and S2 to achieve the regulation of the configuration of the metal nanoarray.

[0046] In some examples, the high-viscosity fluid material includes, but is not limited to, glass or thermoplastic polymer, and the temperature at which the high-viscosity fluid material undergoes rheology is lower than the melting point of the metal nanoarray. When the high-viscosity fluid material is glass (such as Schott P-PK53), the hot pressing conditions are: temperature of 450-500 °C, axial pressure of 0.5-2 kN, and holding time of 20-200 s; when the high-viscosity fluid material is thermoplastic polymer (such as PMMA), the hot pressing conditions are: temperature of 130-160 °C, axial pressure of 0.5-2 kN, and holding time of 20-200 s. When the high-viscosity fluid material is glass, the etching solution is a mixed solution of 5wt%-7wt% phosphoric acid and 1.5wt%-2wt% chromic acid; when the high-viscosity fluid material is thermoplastic polymer, the etching solution is acetone.

[0047] The present invention also provides a method for preparing a metal chiral nanoarray based on thermomechanical deformation and the above method (see Figure 1 , taking the template in the figure as AAO for example), which includes the following steps:

[0048] (1) Stack a metal sheet on a template with an ordered nanopore structure, and extrude the metal under hot pressing conditions so that it undergoes rheology into the nanopore channels of the template to form an ordered metal nanoarray in the template (see Figure 2 );

[0049] (2) Immerse the ordered metal nanoarray in the template in an etching solution for treatment to corrode the surface layer of the template, so that a certain length of the ordered metal nanoarray in the template is exposed (see Figure 3 );

[0050] (3) Apply a directional shear force to the exposed ordered metal nanoarray by using the shear force generated by the flow of the high-viscosity fluid material, so that the ordered metal nanoarray bends along the flow direction (see Figure 4 );

[0051] (4) Repeat steps (2) and (3), and realize the configuration regulation of the metal nanoarray by controlling the exposed length of the ordered metal nanoarray and the direction of the directional shear force to obtain a metal chiral nanoarray (see Figure 5 ).

[0052] In some examples, the template in step (1) includes, but is not limited to, an alumina (AAO) template or a silicon template.

[0053] In some examples, the metal material of the metal sheet in step (1) is gold, silver, aluminum, platinum, copper or an alloy containing at least one of gold, silver, aluminum, platinum, and copper.

[0054] In some examples, the etching solution described in step (2) is a mixed solution of 5 wt% - 7 wt% phosphoric acid and 1.5 wt% - 2 wt% chromic acid.

[0055] In some examples, the temperature at which the ordered metal nanoarray is treated in the etching solution in step (2) is ≤ 60 °C, and the exposed length of the ordered metal nanoarray is regulated by controlling the treatment time of the ordered metal nanoarray in the etching solution.

[0056] In some examples, the metal chiral nanoarray is arranged in a periodic or quasi-periodic array form, and the array period ranges from 60 to 1000 nm.

[0057] In some examples, the metal chiral nanoarray has excellent optical chirality characteristics, its bending direction determines the chiral characteristics, and the reflection asymmetry factor is adjustable within 0.1 - 0.5.

[0058] Example 1

[0059] A left and right metal chiral nanoarray based on thermomechanical deformation, and its preparation method (see Figure 6 ) includes the following steps:

[0060] 101: Preparation of straight metal nanoarray

[0061] Cut a polished aluminum sheet with dimensions of 3 mm × 3 mm × 0.3 mm as the base material, and stack the polished aluminum sheet above an anodic aluminum oxide (AAO) template with a long-range ordered nanopore structure. Subsequently, place the stacked assembly between two hot pressing plates, control the temperature of the hot pressing plates to be 500 ± 5 °C, apply a vertical pressure of 300 MPa to the laminated structure and hold for 10 min. Make the surface layer metal flow into the AAO nanopore channels to form an ordered metal nanoarray in the AAO nanopore channels.

[0062] 102: Etching treatment to expose the metal nanoarray

[0063] Immerse the sample treated in step 101 in a phosphoric acid - chromic acid mixed etching solution, which contains 6 wt% phosphoric acid and 1.8 wt% chromic acid. Control the etching temperature to be 50 ± 2 °C and perform selective etching for 4 h. Take out the etched sample, wash it with deionized water, and then dry it with nitrogen. At this time, the surface layer of the AAO template is partially removed, exposing the head of the metal nanoarray, with a length of 500 ± 100 nm.

[0064] 103: Rheological shear force-induced ordered deformation

[0065] Cut Schott P-PK53 type low-melting glass with dimensions of 2 mm×2 mm×1 mm and place it on one side of the sample obtained in step 102. Place the sample between two hot pressing plates, control the temperature of the hot pressing plates at 460±5 °C, apply an axial pressure of 1 kN to the low-melting glass at a loading rate of 0.3 mm / min, hold for 100 s and then quickly unload at a rate of 100 N / s. During this process, the glass undergoes rheology and applies a directional shear force to the exposed nanostructure array, causing the nanostructures to undergo plastic deformation and bend orderly along the rheology direction.

[0066] 104: Secondary etching and design of chiral nanostructures

[0067] Immerse the sample treated in step 103 into the phosphoric acid-chromic acid mixed solution again. The composition of this solution is the same as that used in step 102. Keep the sample at a temperature of 50±2 °C for 0.5 h to completely corrode the Schott P-PK53 glass on the sample surface. Then continue to corrode for 4 h under the same conditions, and the surface layer of the AAO nanopore template is partially corroded again, and the heads of the metal nanoarrays are exposed. By changing the position where the low-melting glass is placed, the shear direction forms an angle of +90° or -90° with the direction of the first segment, and left-handed and right-handed metal nanostructure arrays are obtained respectively.

[0068] In the actual operation process, if the thickness of the nanowires themselves is not uniform, under the action of the same shear force, different degrees of bending of the nanowires will occur (as shown in Figure 7 a). It can be seen from this that in the preparation process of the nanowires, controlling the pore size uniformity of the template is crucial for precisely controlling the consistency of the nanowire thickness to ensure the stability and reliability of the bending effect. During the process of applying shear force to the nanostructures by the rheology of the high-viscosity fluid material to induce their bending, if the temperature is too high or the applied axial pressure is too small, the nanowires cannot reach a fully bent state (as shown in Figure 7 b); if the temperature is too low or the applied axial pressure is too large, the nanowires will be bent excessively and finally break (as shown in Figure 7 c). Therefore, in the method of the present invention, when the high-viscosity fluid material is glass, control the temperature for its rheology to apply shear force to the nanostructures at 450~500 °C, the axial pressure at 0.5~2 kN, and the holding time at 20~200 s; when the high-viscosity fluid material is a thermoplastic polymer, control the temperature for its rheology to apply shear force to the nanostructures at 130~160 °C, the axial pressure at 0.5~2 kN, and the holding time at 20~200 s, so as to ensure that the three-dimensional metal chiral nanoarray prepared by the method of the present invention has the characteristics of high precision and stability.

[0069] The circular polarization reflection spectrum measurement and reflection circular dichroism spectrum characterization were carried out on the metal chiral nanostructure array prepared in Example 1, specifically including the following steps:

[0070] 1) Circular polarization reflection spectrum measurement

[0071] The circular polarization reflection spectrum was measured under a bright-field confocal microscope system. Specifically, the white light emitted by a halogen lamp passed through a linear polarizer and a quarter-wave plate successively (the linear polarization direction was at ±45 o ° with the fast axis of the quarter-wave plate), and the natural light was modulated into left-handed circularly polarized light or right-handed circularly polarized light. Then, it was focused on the surface of the metal chiral nanostructure array through a 20× objective lens with a numerical aperture of 0.4, and the reflected light signal was collected by a spectrometer through fiber-optic coupling. As Figure 8 shown, when the incident light was left-handed circularly polarized light or right-handed circularly polarized light, the intensities of the circular polarization reflection spectra of the metal chiral nanostructure array at different wavelengths ( I LCP and I RCP ) would have obvious differences.

[0072] 2) Reflection circular dichroism spectrum calculation

[0073] Reflection circular dichroism is a dimensionless parameter used to describe the interaction between circularly polarized light and chiral nanostructures, and is defined as:

[0074] where RCD represents the reflection circular dichroism; I LCP represents the intensity of the circular polarization reflection spectrum of the left-handed metal nanostructure array; I RCP represents the intensity of the circular polarization reflection spectrum of the right-handed metal nanostructure array.

[0075] The results were as Figure 9 shown. The reflection circular dichroism responses of the left- and right-handed nanostructure arrays were strong, and the asymmetry factor could reach up to 0.5 at most, and showed a symmetric trend in the visible light range. This result indicates that the metal chiral nanostructure array of the present invention can have important applications in chiral photoluminescence and other aspects.

[0076] Example 2

[0077] The applications of the left- and right-handed metal nanostructure arrays prepared in Example 1 in circularly polarized light-emitting devices included the following steps:

[0078] 1) Preparation of circularly polarized light-emitting devices based on left- and right-handed metal nanostructure arrays

[0079] First, the left-handed and right-handed metal nanostructure arrays in Example 1 were respectively immersed in a toluene solution containing 0.2 mM perylene molecules for 5 h, taken out and dried. As Figure 10 a and Figure 10 shown in c, at this time, the molecules were adsorbed on the surface of the metal nanostructure arrays.

[0080] 2) Characterization of circularly polarized luminescence performance

[0081] A linearly polarized laser beam with a power of 10 μW and a wavelength of 457 nm was focused on the surface of the chiral nanostructure array to excite the perylene molecules to emit light (as shown in Figure 10 b and Figure 10 d). The circularly polarized luminescence spectra were collected through left- and right-handed circular polarizers. As shown in Figure 11 a and Figure 11 b, the circularly polarized luminescence device of this chiral metal nanostructure array could emit fluorescence with strong intensity and had an obvious chiral response. As shown in Figure 11 c, the luminescence asymmetry factor of the circularly polarized luminescence devices based on the left- and right-handed metal nanostructure arrays was ±0.3.

[0082] The present invention uses the shear force generated by the flow of a highly viscous fluid to apply a directional shear force to the exposed metal nanoarray, causing the metal nanoarray to bend along the flow direction, and realizes the configuration regulation of the metal nanoarray by regulating the length of the exposed metal nanoarray and the intensity / direction of the directional shear force, thereby preparing a three-dimensional metal chiral nanoarray with high forming accuracy and surface integrity, solving the problems of high internal porosity, large surface roughness, and low efficiency in the prior art. The metal chiral nanoarray prepared by the present invention has excellent optical chiral characteristics, its bending direction determines the chiral characteristics and the reflection asymmetry factor is adjustable in the range of 0.1 - 0.5, and the luminescence asymmetry factor can reach 0.3, having good application prospects in the field of precision optical devices.

[0083] The above specific embodiments have described the implementation of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solutions of the present invention, and these simple variations all belong to the protection scope of the present invention.

Claims

1. A method for configuring and regulating a large-area metal nanoarray by using rheological shear force, characterized in that It includes the following steps: S1. Place the high-viscosity fluid material above the metal nanoarray and bias it to one side. Under hot pressing conditions, make the high-viscosity fluid material rheological. Use the shear force generated by the flow of the high-viscosity fluid material to apply a directional shear force to the metal nanoarray in contact with it, so that the metal nanoarray bends along the flow direction; S2. Repeat step S1 to realize the configuration regulation of the metal nanoarray by controlling the contact part and the direction of the directional shear force.

2. A method for configuring and regulating a large-area metal nanoarray by using rheological shear force according to claim 1, characterized in that The high-viscosity fluid material includes, but is not limited to, glass or thermoplastic polymer, and the temperature at which the high-viscosity fluid material undergoes rheology is lower than the melting point of the metal nanoarray.

3. A method for configuring and regulating a large-area metal nanoarray by using rheological shear force according to claim 2, characterized in that When the high-viscosity fluid material is glass, the hot pressing conditions are: temperature is 450~500 °C, axial pressure is 0.5~2 kN, and the holding time is 20~200 s; when the high-viscosity fluid material is thermoplastic polymer, the hot pressing conditions are: temperature is 130~160 °C, axial pressure is 0.5~2 kN, and the holding time is 20~200 s.

4. A method for preparing a metal chiral nanoarray based on thermomechanical deformation and the method according to any one of claims 1 to 3, characterized in that, It includes the following steps: (1) Stack the metal sheet on the template with an ordered nanoporous structure. Under hot pressing conditions, extrude the metal to make it rheological into the nanopores of the template to form an ordered metal nanoarray in the template; (2) Immerse the ordered metal nanoarray in the template in the etching solution for treatment to corrode the surface layer of the template, so that a certain length of the ordered metal nanoarray in the template is exposed; (3) Use the shear force generated by the flow of the high-viscosity fluid material to apply a directional shear force to the exposed ordered metal nanoarray, so that the ordered metal nanoarray bends along the flow direction; (4) Repeat steps (2) and (3) to realize the configuration regulation of the metal nanoarray by controlling the exposed length of the ordered metal nanoarray and the direction of the directional shear force, and obtain a metal chiral nanoarray.

5. The method for preparing a metal chiral nanoarray according to claim 4, wherein In step (1), the metal material of the metal sheet is gold, silver, aluminum, platinum, copper or an alloy containing at least one of gold, silver, aluminum, platinum, and copper.

6. The method for preparing a metal chiral nanoarray according to claim 4, wherein In step (2), the etching solution is a mixed solution of 5wt%~7wt% phosphoric acid and 1.5wt%~2wt% chromic acid.

7. The method for preparing a metal chiral nanoarray according to claim 4, characterized in that, In step (2), the temperature at which the ordered metal nanoarray is treated in the etching solution ≤ 60 °C, and the exposed length of the ordered metal nanoarray is regulated by controlling the treatment time of the ordered metal nanoarray in the etching solution.

8. The method for preparing a metal chiral nanoarray according to claim 4, wherein The reflection asymmetry factor of the metal chiral nanoarray is adjustable within 0.1~0.

5.

9. The metal chiral nanoarray prepared by the method described in claim 4.

10. The application of the metal chiral nanoarray described in claim 9 in circularly polarized luminescence, chiral molecule sensing, optical imaging, information storage, photoelectric detection or flexible wearable devices.

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