A nano-moonie array structure for enhancing chiral optics

Abstract

The application relates to the technical field of production and processing, and particularly discloses a nano crescent array structure for enhancing chiral optics, which comprises a first substrate and a crescent-shaped metal on the first substrate; wherein the crescent-shaped metal is a chiral structure unit arranged in a hexagonal array on the upper surface of the first substrate; the chiral structure unit comprises crescent-shaped metals with adjustable irregularities and equal interval distances between crescent centers, the crescent-shaped metals are arranged in a hexagonal array on the upper surface of the first substrate, and the irregularities of the crescent-shaped metals are adjustable; the chiral structure unit is uniformly arranged in the transverse and longitudinal directions of the first substrate; and the material of the first substrate is a light-transmitting material. The nano crescent array structure for enhancing chiral optics significantly enhances the circular dichroism of the chiral optical structure by increasing a regular hexagonal arrangement mode on the basis of original single irregular crescent-shaped metal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical array structure, in particular to a nano crescent array structure for enhancing chiral optics. BACKGROUND

[0002] Chirality refers to the property that a structure cannot coincide with its mirror image, and chiral structures exist universally in nature, such as biological macromolecules such as proteins, saccharides and DNA. Chirality plays a key role in biochemistry and life evolution. Chirality can be divided into intrinsic chirality and extrinsic chirality according to its structural characteristics. Intrinsic chirality refers to the chirality of the structure itself, and extrinsic chirality refers to the chirality of the structure together with incident light.

[0003] Circular dichroism (CD) is an optical technique for measuring the difference in absorption of circularly polarized light by a molecule, and is a very important means for studying chiral compounds. In the study of the asymmetry of chiral molecules, when left-handed circularly polarized light and right-handed circularly polarized light are incident, chiral materials will exhibit different effective refractive indices and different propagation speeds. Because the interaction between chiral molecules and electromagnetic waves is very weak, the sensitivity and accuracy of detection are greatly limited.

[0004] In the prior art, by designing a two-dimensional metal chiral structure, the polarization characteristics of the light beam can be modulated or used to detect the circular dichroism of chiral substances, but when the detected signal itself is relatively weak, the obtained circular dichroism signal is not obvious, that is, the detection effect is not good.

[0005] Therefore, we propose a nano crescent array structure for enhancing chiral optics to solve the above problems. SUMMARY

[0006] The present application aims to provide a nano crescent array structure for enhancing chiral optics to solve the problem that when the detected signal itself is relatively weak, the obtained circular dichroism signal is not obvious and the detection effect is not good in the detection of chiral substances by the circular dichroism of chiral structures.

[0007] To achieve the above object, the present application provides the following technical scheme: a nano crescent array structure for enhancing chiral optics, comprising: a first substrate and a crescent-shaped metal on the first substrate; wherein the crescent-shaped metal is a chiral structure unit arranged in a hexagonal array on the upper surface of the first substrate, and the chiral structure unit comprises: metal crescents with adjustable irregularities and equal interval distances between the centers of the crescents.

[0008] Preferably, the metal crescents are arranged in a hexagonal array on the upper surface of the first substrate, and the irregularities of the metal crescents are adjustable.

[0009] Preferably, the chiral structural units are arranged uniformly in both the horizontal and vertical directions of the first substrate.

[0010] Preferably, the period of arrangement of the chiral structural units in the horizontal direction ranges from 400 to 500 nm.

[0011] Preferably, the period of arrangement of the chiral structural units in the vertical direction ranges from 400 to 500 nm. nm.

[0012] Preferably, the chiral structural units are arranged with the same spacing between each center point.

[0013] Preferably, the material of the first substrate is a light-transmitting material.

[0014] Compared with the prior art, the present application has at least the following beneficial effects: the nano-moon array structure for enhancing chiral optics, by increasing the regular hexagonal arrangement mode on the basis of the original single irregular metal moon, the circular dichroism of the chiral optical structure is significantly enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the application without imposing undue limitation thereon. In the drawings:

[0016] Figure 1 is a schematic diagram of the three-dimensional structure of the present application;

[0017] Figure 2 is a schematic diagram of the top view of the structure of the present application;

[0018] Figure 3 is a schematic diagram of the chiral structural unit of the present application;

[0019] Figure 4 is a schematic diagram of the irregularity of the moon of the chiral structural unit of the present application;

[0020] Figure 5 is a schematic diagram of the principle of circular dichroism of the present application;

[0021] Figure 6 is a comparative diagram of the chiral structural unit of the present application without regular hexagonal array arrangement;

[0022] Figure 7 is a comparative diagram of the chiral structural unit of the present application with regular hexagonal array arrangement;

[0023] Figure 8 is a circular dichroism transmission spectrum diagram of the chiral structural unit of the present application with periodic array arrangement of metal moons.

[0024] Figure 9 Figure 1 is a contrastive chart of unit circular dichroism of the present application.

[0025] Figure 1 is a contrastive chart of unit circular dichroism of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, so that the realization process of how to apply technical means to solve technical problems and achieve technical effects of the present application can be fully understood and implemented. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments.

[0027] Please refer to Figures 1-9 The present application provides the following technical solutions:

[0028] The present application provides the following technical solutions:

[0029] Embodiment one

[0030] Please refer to Figure 1 and Figure 2 The chiral optical array structure comprises a first substrate 11 and a metal crescent 12 arranged on the first substrate 11.

[0031] The material of the first substrate 11 is a material with high transmittance to the used light wave band, such as silicon dioxide, quartz, etc.

[0032] The first substrate 11 is provided with a plurality of chiral structure units 13 arranged in a regular hexagonal array on the upper surface of the first substrate 11. The chiral structure unit 13 comprises a complete metal crescent 12 in the center and four incomplete metal crescents (the four incomplete metal crescents can be spliced into a complete metal crescent) around the complete metal crescent 12.

[0033] The metal crescents 12 are uniformly arranged in the horizontal and vertical directions of the chiral structure unit 13. The period of the arrangement of the metal crescents 12 in the horizontal direction is Px, and the period of the arrangement of the metal crescents 12 in the vertical direction is Py. The length of Px ranges from 400 nm to 500 nm, and the length of Py ranges from 400 nm to 500 nm. nm.

[0034] Please refer to Figure 3The chiral structural unit includes a second base 21, a central metal crescent 22 located on the second base 21, and a fragmented metal crescent 23 located on the second base 21 and surrounding the central metal crescent 22.

[0035] Each of the metal crescent-shaped parts has the same height.

[0036] The thickness of the central metal crescent 22 is 100nm. The material of the central metal crescent 22 is a good conductor, including precious metals such as gold, silver, copper, and aluminum.

[0037] In this embodiment of the invention, the standard for the irregularity of the metallic crescent shape in the chiral structural unit is defined by two ellipses that are perpendicularly cut to each other horizontally and vertically. The crescent-shaped morphology protruding horizontally is taken as the specific morphology under study. Please refer to [link / reference]. Figure 4 To prevent the horizontal ellipse from coinciding with the boundary of the vertical ellipse during vertical cutting, the experimental example of this invention sets the horizontal and vertical diameters L1 and L2 of the vertically arranged ellipses to be 160 nm and 250 nm, respectively; and the horizontal and vertical diameters L3 and L2 of the horizontally arranged ellipses to be 150 nm and 250 nm, respectively. Keeping the horizontally arranged ellipse unchanged, the vertically arranged ellipse is moved only along the y-axis, with a movement distance L4 ranging from 10 nm to 30 nm. The shadow crescent 32 is used in this invention, and the third substrate 31 is the same as the second substrate 21 described above.

[0038] The central metallic crescent 22 is made of gold, and the horizontal period Px and vertical period Py of the chiral structural unit 13 are 500 nm in length. nm, the thickness of the metal crescent 22 is 100nm; the irregularity of the metal crescent 22 is the aforementioned cutting ellipse shift L4=20nm.

[0039] The chiral optical array structure of the present invention significantly enhances the circular dichroism of the chiral optical structure by using an irregular metal crescent array structure with a periodic regular hexagonal matrix arrangement.

[0040] Example 2

[0041] Please see Figure 5 When a beam of left-circularly polarized (LCP) light is incident from the front of the chiral optical structure at a perpendicular angle, the transmittance of the received left-circularly polarized light after passing through the chiral optical array structure is T--. When a beam of right-circularly polarized (RCP) light is incident from the front of the chiral optical structure at the same incident angle, the transmittance of the received right-circularly polarized light after passing through the chiral optical structure is T++, where the subscript "--" indicates left-circularly polarized light and "++" indicates right-circularly polarized light. The circular dichroism of the chiral structural unit 13 can then be expressed as:

[0042] CD = (T++ - T--) / (T+++ T--)

[0043] The transmittance of left-handed polarized light and right-handed polarized light after passing through the chiral optical device is different, that is, T++ ≠ T--, therefore, the size of CD represents the strength of the circular dichroism of the chiral optical device.

[0044] Please refer to Figure 6 and Figure 7 , wherein the central metal crescent 22 adopts gold material, the horizontal period Px and the vertical period Py of the chiral structure unit 13 are 500 nm and 500 nm respectively, nm, the thickness of the central metal crescent 22 is 100 nm; the irregularity of the central metal crescent 22 is that the above-mentioned cutting ellipse moves L4 = 20 nm.

[0045] Please refer to Figure 8 , wherein “T--” represents left-handed polarized light, “T++” represents right-handed polarized light; the circularly polarized light is in the z-x plane, and the left-handed and right-handed light is vertically incident on the chiral structure unit 13 added with a hexagonal array structure, to obtain Figure 8 ;

[0046] Please refer to Figure 9 , wherein the circularly polarized light is in the z-x plane, and the left-handed and right-handed light is vertically incident on the chiral structure unit 13 without adding a regular hexagonal array structure (as shown in Figure 6 ) and the chiral structure unit 13 added with a regular hexagonal array structure (as shown in Figure 7 ), to obtain Figure 9 .

[0047] As can be seen from Figure 9 , the CD at the wavelength λ = 660 nm on the CD spectrum of the chiral structure unit 13 without adding a regular hexagonal array structure is 1.5%, and the CD at the wavelength λ = 660 nm on the CD spectrum of the chiral structure unit 13 added with a regular hexagonal array structure is 12%. This is because, before adding the regular hexagonal array structure, the chiral structure unit 13 only generates an electric dipole, and the addition of the regular hexagonal array structure changes the current flow direction on the original basic chiral structure unit 13, and a magnetic dipole appears between the metal crescents. Due to the joint action of the electric dipole and the magnetic dipole, the CD signal is significantly enhanced.

[0048] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative labor shall fall within the protection scope of the present application; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to part of the technical features, as long as the modifications, equivalent replacements, improvements, etc. are within the spirit and principle of the present application, and shall be included in the protection scope of the present application.

Claims

1. A nano-lunar array structure for enhancing chiral optics, characterized in that, The application relates to a chiral structure unit (13) arranged on a first substrate (11) in a crescent-shaped metal, wherein the chiral structure unit (13) is a chiral structure unit (13) arranged on the upper surface of the first substrate (11) in a hexagonal array, and the chiral structure unit (13) comprises metal crescents (12) with adjustable irregularities and equal interval distances between the centers of the crescents. The chiral structure unit (13) comprises a complete metal crescent (12) in the center and four incomplete metal crescents around the complete metal crescent (12), and the four incomplete metal crescents can be spliced into a complete metal crescent (12); the adjustable irregularity is defined by cutting two ellipses horizontally and vertically according to the irregularity size standard of the metal crescents (12) in the chiral structure unit (13); the crescent-shaped form protruding in the horizontal direction is taken as the specific topography for research, so that the horizontal ellipses will not coincide with the boundary of the vertical ellipses when the horizontal ellipses are cut by moving up and down. The metal crescents (12) are arranged on the upper surface of the first substrate (11) in a hexagonal array, and the irregularity of the metal crescents (12) is adjustable.

2. The nano-moonilune array structure for enhancing chiral optics of claim 1, wherein: The chiral structure units (13) are uniformly arranged in the horizontal direction and the vertical direction of the first substrate (11).

3. The nano-moonilune array structure for enhancing chiral optics of claim 1, wherein: The period of the chiral structure units (13) arranged in the horizontal direction ranges from 400 to 500 nm.

4. The nano-moonilune array structure for enhancing chiral optics of claim 1, wherein: The interval distances between the centers of the chiral structure units (13) are equal.

5. The nano-moonilune array structure for enhancing chiral optics of claim 1, wherein: The period of the vertical arrangement of the chiral structure units (13) is in the range of nm.

6. The nano-moonilune array structure for enhancing chiral optics of claim 1, wherein: The material of the first substrate (11) is a light-transmitting material.

7. The nano-moonilune array structure for enhancing chiral optics of claim 1, wherein: ​

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