Asymmetric H-type micro-nano structure for realizing strong circular dichroism

Abstract

The invention relates to the technical field of circular dichroism application, and particularly discloses an asymmetric H-type micro-nano structure for realizing strong circular dichroism, the asymmetric H-type micro-nano structure comprises a substrate layer and a micro-nano structure layer, the micro-nano structure layer is arranged on the substrate layer, and the micro-nano structure layer comprises chiral units arranged periodically. The H-type nanostructure is endowed with chiral characteristics. When the asymmetric H-type nano structure is excited by circular polarized light, the asymmetric H-type nano structure can generate a surface plasmon resonance phenomenon. Particularly, the number and the coupling mode of the generated harmonic oscillators under the excitation of the right-handed circular polarized light are obviously different from the number and the coupling mode of the dipoles generated under the excitation of the left-handed circular polarized light.

Description

Technical Field

[0001] The invention belongs to the technical field of circular dichroism application, and in particular relates to an asymmetric H-type micro-nano structure for realizing strong circular dichroism. Background Art

[0002] There are many chiral substances in nature, such as drug molecules, DNA, RNA, etc., and in most cases, we rely on their specific structures and chiral characteristics.

[0003] These structures all carry chiral signals, namely circular dichroism signals, which are used as an effective means to distinguish and identify chirality. However, the chiral signals of most substances in nature are relatively weak and difficult to detect. In contrast, artificial chiral nanostructures can significantly enhance the circular dichroism of molecules (E. Hendry, Nature Nanotechnology, 5, 783–787, 2010), thus effectively making up for this shortcoming.

[0004] Photons not only carry energy, but also have linear momentum. However, efficiently converting the energy of photons into rotational force has always been a major challenge in the field of scientific research. In traditional methods, although Sir Crookes' radiometer successfully demonstrated the linear momentum effect of photons, its rotational effect is limited by the thermal permeability effect and is difficult to fully exert. In order to break through this limitation, the scientific community continues to explore new methods and approaches. In recent years, chiral nanostructures have attracted much attention due to their unique optical properties.

[0005] Artificial structures can significantly enhance the circular dichroism of molecules and generate strong rotational forces under light excitation, providing new possibilities for photon energy conversion. However, the existing technology still lacks a new structure that can effectively combine the advantages of chiral nanostructures and realize the efficient conversion of photon energy into rotational forces. Summary of the invention

[0006] The purpose of the present invention is to provide an asymmetric H-type micro-nano structure that achieves strong circular dichroism to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] An asymmetric H-type micro-nano structure for achieving strong circular dichroism comprises a substrate layer and a micro-nano structure layer, wherein the micro-nano structure layer is disposed on the substrate layer, the micro-nano structure layer comprises periodically arranged chiral units, the chiral units comprise a dielectric layer film and a noble metal chiral structure, the noble metal chiral structure is disposed on the dielectric layer film, the noble metal chiral structure further comprises a first arm, a second arm, a third arm, a fourth arm and a connecting rod, wherein the first arm, the second arm, the third arm and the fourth arm are respectively connected to the surface of the connecting rod.

[0009] Preferably, the first arm, the second arm, the third arm and the fourth arm are respectively located at the upper right, lower right, lower left and upper left of the connecting rod.

[0010] Preferably, the substrate layer is conductive glass, and the material is silicon dioxide.

[0011] Preferably, the material of the noble metal chiral structure is gold or silver.

[0012] Preferably, the connecting rod is laterally located at the center of the substrate layer, has a thickness of 40 nanometers, a width of 60 nanometers, and a length of 250 nanometers.

[0013] Preferably, the first arm is located above and to the right of the connecting rod, and has a thickness of 40 nanometers, a width of 60 nanometers, and a length of 200 nanometers.

[0014] Preferably, the second arm is located below and to the right of the connecting rod and is 20 nanometers lower than the connecting rod, has a thickness of 40 nanometers, a width of 60 nanometers, and a length of 200 nanometers.

[0015] Preferably, the third arm is located below and to the left of the connecting rod, and has a thickness of 40 nanometers, a width of 60 nanometers, and a length of 200 nanometers.

[0016] Preferably, the fourth arm is located above and to the left of the connecting rod and is 20 nanometers higher than the connecting rod, 40 nanometers thick, 60 nanometers wide and 200 nanometers long.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] Beneficial effects of the invention: The invention provides a double-layer chiral structure for achieving strong circular dichroism, comprising a substrate and a metal asymmetric H-type chiral nanostructure, and a non-chiral nanostructure consisting of five parts: a first noble metal arm, a second noble metal arm, a third noble metal arm, a fourth noble metal arm and a connecting rod. The four arms are asymmetrically connected to the connecting rod to form a non-chiral structure.

[0019] In the present invention, by breaking the symmetry, the H-type nanostructure is endowed with chiral characteristics. When excited by circularly polarized light, a surface plasmon resonance phenomenon will occur on this asymmetric H-type nanostructure. In particular, under the excitation of right-handed circularly polarized light, the number of resonators and their coupling modes generated are significantly different from the number of dipoles and their coupling modes generated under the excitation of left-handed circularly polarized light. This difference further leads to different distributions of electric field strength inside the nanostructure, thereby producing a significant circular dichroism effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the general assembly structure of the present invention;

[0021] Figure 2 It is the absorption spectrum and circular dichroism spectrum diagram of the asymmetric H-type micro-nano chiral structure of the present invention;

[0022] Figure 3 It is the charge distribution diagram on the asymmetric H-type micro-nanostructure when illuminated by different circularly polarized lights at the resonance peak;

[0023] Figure 4 The two-arm structure changed from the asymmetric H-type chiral structure.

[0024] Figure 5 The three-arm structure is changed from the asymmetric H-type chiral structure.

[0025] Figure 6 The three-arm structure is changed from the asymmetric H-type chiral structure.

[0026] In the figure: 1, first arm; 2, second arm; 3, third arm; 4, fourth arm; 5, connecting rod; 6, substrate layer. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Embodiment 1:

[0029] An asymmetric H-type micro-nanostructure for realizing circular dichroism includes a bottom and periodically arranged chiral asymmetric H-type units.

[0030] The bottom material is glass, and the asymmetric H-shaped structure material is gold. The periodically arranged chiral units contained in the asymmetric H-shaped micro-nanostructure are planar structures with a thickness of 40 nanometers.

[0031] Each unit is composed of five small blocks: the middle is a connecting rod with a width of 60 nanometers and a length of 250 nanometers. The four arms of the asymmetric H-shaped micro-nanostructure are all 60 nanometers wide and 200 nanometers long. The first arm is located on the upper right side of the connecting rod; the second arm is located on the lower right side of the connecting rod, but 40 nanometers away from the side. The third arm is located on the lower left side of the connecting rod. The fourth arm is located on the upper left side of the connecting rod, but 40 nanometers away from the side. The asymmetric position of the four arms makes the asymmetric H-shaped micro-nanostructure chiral.

[0032] In order to generate circular dichroism signals, circularly polarized light is irradiated on the surface of the asymmetric H-shaped structure, and the absorption difference between right-handed circularly polarized light and left-handed circularly polarized light, i.e. circular dichroism, is examined.

[0033] When excited by different circularly polarized light, the resonance intensity, coupling mode and resonance mode will result in different surface plasmon resonances.

[0034] Embodiment 2:

[0035] Based on Example 1, Figure 4 As shown, the first and third arms of the asymmetric H-shaped micro-nanostructure are removed. The remaining two arms connect the upper and lower surfaces of the rod, on both sides of the symmetry axis, and this structure will not overlap with its own mirror image and has chirality.

[0036] Embodiment three:

[0037] Based on Example 1, Figure 5 As shown, the second arm of the asymmetric H-shaped micro-nanostructure is removed. The remaining three arms are connected to the rods respectively. This structure will not overlap with its own mirror image and has chirality.

[0038] Embodiment 4:

[0039] Based on Example 3, Figure 6 As shown, the height of the first arm of the asymmetric H-shaped micro-nanostructure is different from that of other parts, and the height of the first arm is 60 nanometers. The three arms are connected to the rods respectively, which also destroys the symmetry in the vertical direction and enhances the chirality of the structure.

[0040] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0041] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An asymmetric H-type micro-nanostructure for achieving strong circular dichroism, characterized in that: The invention comprises a substrate layer (6) and a micro-nano structure layer, wherein the micro-nano structure layer is disposed on the substrate layer (6), the micro-nano structure layer comprises periodically arranged chiral units, the chiral units comprise a dielectric layer film and a noble metal chiral structure, the noble metal chiral structure is disposed on the dielectric layer film, the noble metal chiral structure further comprises a first arm (1), a second arm (2), a third arm (3), a fourth arm (4) and a connecting rod (5), wherein the first arm (1), the second arm (2), the third arm (3) and the fourth arm (4) are respectively connected to the surface of the connecting rod (5).

2. The asymmetric H-shaped micro-nanostructure for achieving strong circular dichroism according to claim 1, characterized in that: The first arm (1), the second arm (2), the third arm (3) and the fourth arm (4) are respectively located at the upper right, lower right, lower left and upper left of the connecting rod.

3. The asymmetric H-shaped micro-nanostructure for achieving strong circular dichroism according to claim 2, characterized in that: The substrate layer (6) is conductive glass, and its material is silicon dioxide.

4. The asymmetric H-shaped micro-nanostructure for achieving strong circular dichroism according to claim 3, characterized in that: The material of the noble metal chiral structure is gold or silver.

5. The asymmetric H-shaped micro-nanostructure for achieving strong circular dichroism according to claim 4, characterized in that: The connecting rod (5) is laterally located at the center of the substrate layer (6), has a thickness of 40 nanometers, a width of 60 nanometers and a length of 250 nanometers.

6. The asymmetric H-shaped micro-nanostructure for achieving strong circular dichroism according to claim 5, characterized in that: The first arm (1) is located above and to the right of the connecting rod (5), has a thickness of 40 nanometers, a width of 60 nanometers and a length of 200 nanometers.

7. The asymmetric H-shaped micro-nanostructure for achieving strong circular dichroism according to claim 6, characterized in that: The second arm (2) is located below and to the right of the connecting rod (5) and is 20 nanometers lower than the connecting rod (5), has a thickness of 40 nanometers, a width of 60 nanometers and a length of 200 nanometers.

8. The asymmetric H-shaped micro-nanostructure for achieving strong circular dichroism according to claim 7, characterized in that: The third arm (3) is located below and to the left of the connecting rod (5), and has a thickness of 40 nanometers, a width of 60 nanometers, and a length of 200 nanometers.

9. The asymmetric H-shaped micro-nanostructure for achieving strong circular dichroism according to claim 8, characterized in that: The fourth arm (4) is located above and to the left of the connecting rod (5) and is 20 nanometers higher than the connecting rod (5), 40 nanometers thick, 60 nanometers wide and 200 nanometers long.

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