A device for regulating circularly polarized light emission

Abstract

The present application relates to a device for regulating circularly polarized luminescence, and to the technical field of circularly polarized luminescent devices. In the present invention, a graphene layer is arranged on one side of a substrate, a first nanowire and a second nanowire are both arranged on a side of the graphene layer away from the substrate, a first nanorod is vertically arranged on a side of the first nanowire close to the second nanowire, a second nanorod is vertically arranged on a side of the second nanowire close to the first nanowire, a first magnetostrictive material portion is arranged on a side of the first nanorod away from the second nanorod, a second magnetostrictive material portion is arranged on a side of the second nanorod away from the first nanorod, and a fluorescent molecular layer is coated on the surface of the structural layer and the graphene layer away from the substrate; the device of the present application achieves regulation of circularly polarized luminescence by regulating the chiral field around the device through an external magnetic field. The regulation method of the present invention is simple and has good application prospects in the field of circularly polarized luminescence.

Description

Technical Field

[0001] The present invention relates to the technical field of circularly polarized light-emitting devices, and in particular to a device for regulating circularly polarized light emission. Background Art

[0002] Circularly polarized luminescence (CPL) refers to the phenomenon that a chiral luminescent substance emits left-handed or right-handed circularly polarized light upon stimulation. Circularly polarized luminescence has a wide range of uses and application prospects in the fields of luminescent materials, asymmetric catalysis, information storage and encryption, optical display, nonlinear optics, etc. In order to broaden the application of chiral optics and electronics, it is urgent to regulate the intensity or central wavelength of circularly polarized luminescence.

[0003] In the prior art, methods for achieving circularly polarized luminescence include (1) using chiral luminescent molecules or chiral luminescent systems to achieve circularly polarized luminescence and (2) using the chiral field generated by chiral micro-nanometallic structures to excite chiral luminescent molecules to achieve circularly polarized luminescence.

[0004] For circularly polarized luminescence regulation, the conventional approach is to achieve circularly polarized luminescence regulation by changing the microstructure of chiral luminescent molecules. For example, the polymer chain of L-polylactic acid has a helical conformation. By introducing unbalanced surface stress during the crystallization process, wafers with different degrees of distortion are formed to achieve different circularly polarized luminescence. In the method of achieving circularly polarized luminescence regulation by changing the microscopic morphology of chiral luminescent molecules, different control methods need to be adopted for different chiral luminescent molecules, and different control techniques need to be mastered, and the control scheme is not universal.

[0005] By regulating the chiral micro-nano metal structure, changing the chiral field it produces, and then regulating the circularly polarized luminescence, a new strategy for regulating circularly polarized luminescence has been proposed. Generally speaking, after the chiral micro-nano metal structure is prepared, the morphological parameters of the micro-nano metal structure are not easy to regulate. If you want to regulate its circularly polarized luminescence signal, you need to re-prepare the micro-nano metal structure, which causes problems such as waste of resources and complicated process. Summary of the invention

[0006] To solve the above problems, the present invention provides a device for regulating circularly polarized luminescence, comprising: a substrate, a graphene layer, a structural layer and a fluorescent molecular layer; wherein the structural layer comprises a plurality of periodically arranged structural parts, each of which comprises: a first nanowire, a second nanowire, a first nanorod, a second nanorod, a first magnetostrictive material part and a second magnetostrictive material part; the graphene layer is arranged on one side of the substrate, the first nanowire and the second nanowire are arranged parallel to each other on a side of the graphene layer away from the substrate, the first nanorod is connected to a side of the first nanowire close to the second nanowire, the second nanorod is vertically connected to a side of the second nanowire close to the first nanowire, the first magnetostrictive material part is arranged on a side of the first nanorod away from the second nanorod, the second magnetostrictive material part is arranged on a side of the second nanorod away from the first nanorod, and the fluorescent molecular layer is coated on the surface of the structural layer and the graphene layer away from the substrate.

[0007] Furthermore, the material of the first nanowire and the second nanowire is a noble metal.

[0008] Furthermore, the materials of the first nanorods and the second nanorods are noble metals.

[0009] Furthermore, the materials of the first magnetostrictive material portion and the second magnetostrictive material portion are iron gallium, iron silicon boron or nickel materials.

[0010] Furthermore, the material of the substrate is silicon.

[0011] Furthermore, a vertical distance between the first nanowire and the second nanowire is 200nm-400nm.

[0012] Furthermore, the lengths of the first nanorod and the second nanorod are 50nm-300nm.

[0013] Furthermore, the width of the first nanorod and the second nanorod is 40nm-80nm.

[0014] Furthermore, a vertical distance between the first nanorod and the second nanorod is 20 nm-120 nm.

[0015] Furthermore, the first nanowire, the second nanowire, the first nanorod, and the second nanorod have the same height.

[0016] Beneficial effects of the present invention: The present invention provides a device for regulating circularly polarized luminescence. When used, the excitation light irradiates the fluorescent molecules and the structural layer. Under the irradiation of the excitation light, the surface plasmon effect is generated on the first nanowire, the second nanowire, the first nanorod, and the second nanorod, and a strong chiral field is gathered among them. Since the first nanowire, the second nanowire, the first nanorod, and the second nanorod constitute a chiral structure, chiral fields of different chiral intensities are generated under the irradiation of the excitation light. These chiral fields of different chiral intensities excite the chiral luminescent molecules to achieve circularly polarized luminescence. Furthermore, the graphene layer arranged under the structural layer gathers a stronger chiral field due to interlayer coupling, thereby improving the luminescence intensity. When regulating the circularly polarized luminescence, the external magnetic field acts on the first magnetostrictive material part and the second magnetostrictive material part, so that the size of the first magnetostrictive material part and the second magnetostrictive material part increases, squeezes the first nanorod and the second nanorod, changes the surface plasmon resonance of the first nanowire, the second nanowire, the first nanorod, and the second nanorod, and changes the chiral field among them, thereby achieving circularly polarized luminescence regulation. The present invention achieves circularly polarized luminescence regulation by regulating the chiral field. When regulating circularly polarized luminescence, there is no need to re-prepare the structure, and it can be applied to different chiral luminescent molecules. It has a wide application surface and has good application prospects in the field of circularly polarized luminescence.

[0017] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A front view of a device for regulating circularly polarized light emission provided by one embodiment of the present invention;

[0019] Figure 2 A top view of another device for regulating circularly polarized light emission provided by an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the structure of another device for regulating circularly polarized light emission provided by an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the structure of another device for regulating circularly polarized light emission provided by an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of the structure of another device for regulating circularly polarized light emission provided by an embodiment of the present invention.

[0023] In the figure: 10, substrate; 20, graphene layer; 30, structural layer; 31, first nanowire; 32, second nanowire; 33, first nanorod; 34, second nanorod; 35, first magnetostrictive material portion; 36, second magnetostrictive material portion; 37, third magnetostrictive material portion; 38, fourth magnetostrictive material portion; 40, fluorescent molecule layer; 50, second graphene layer; 60, third nanorod. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples.

[0025] Example 1

[0026] Figure 1 A front view of a device for regulating circularly polarized light emission provided by one embodiment of the present invention;

[0027] Figure 2 A top view of another device for regulating circularly polarized light emission provided by an embodiment of the present invention. Figure 1 and Figure 2 As shown, the device for regulating circularly polarized light emission in this embodiment includes: a substrate 10, a graphene layer 20, a structural layer 30 and a fluorescent molecule layer 40. The graphene layer 20 is disposed on the substrate 10, and the structural layer 30 is disposed on the graphene layer 20. The structural layer 30 includes a plurality of periodically arranged structural parts, each of which includes: a first nanowire 31, a second nanowire 32, a first nanorod 33, a second nanorod 34, a first magnetostrictive material part 35 and a second magnetostrictive material part 36. The graphene layer 20 is arranged on one side of the substrate 10, the first nanowire 31 and the second nanowire 32 are both arranged on the side of the graphene layer 20 away from the substrate 10, and the first nanowire 31 and the second nanowire 32 are parallel to each other, the first nanorod 33 is vertically arranged on the side of the first nanowire 31 close to the second nanowire 32, and the second nanorod 34 is vertically arranged on the side of the second nanowire 32 close to the first nanowire 31, that is, the first nanorod 33 and the second nanorod 34 are arranged on the inner side of the first nanowire 31 and the second nanowire 32, and the extension lines of the first nanorod 33 and the second nanorod 34 do not overlap, that is, the first nanorod 33 and the second nanorod 34 are staggered. The first magnetostrictive material part 35 is arranged on the side of the first nanorod 33 away from the second nanorod 34, and the second magnetostrictive material part 36 is arranged on the side of the second nanorod 34 away from the first nanorod 33, and the fluorescent molecule layer 40 is coated on the surface of the structural layer 30 and the graphene layer 20 away from the substrate 10.

[0028] Under the irradiation of excitation light, a surface plasmon effect is generated on the first nanowire 31, the second nanowire 32, the first nanorod 33, and the second nanorod 34, and a strong chiral field is gathered between and near them. Since the first nanowire 31, the second nanowire 32, the first nanorod 33, and the second nanorod 34 constitute a chiral structure, chiral fields of different chiral intensities are generated, and these chiral fields of different chiral intensities excite the luminescent molecules to achieve circularly polarized luminescence. Furthermore, the graphene layer 20 disposed under the structural layer 30 gathers a stronger chiral field due to interlayer coupling, thereby improving the luminescence intensity. When regulating circularly polarized luminescence, an external magnetic field acts on the first magnetostrictive material part 35 and the second magnetostrictive material part 36, so that the size of the first magnetostrictive material part 35 and the second magnetostrictive material part 36 increases, squeezing the first nanorod 33 and the second nanorod 34, changing the surface plasmon resonance of the first nanowire 31, the second nanowire 32, the first nanorod 33, and the second nanorod 34, and changing the chiral field between them, thereby achieving circularly polarized luminescence regulation. The present invention realizes circular polarized luminescence regulation by regulating the chiral field. When regulating circular polarized luminescence, there is no need to re-prepare the structure, and it can be applied to different chiral luminescent molecules, with a wide range of applications, and has good application prospects in the field of circular polarized luminescence.

[0029] In this embodiment, the material of the substrate 10 is silicon dioxide, and the substrate 10 is used to carry the graphene layer 20, the structural layer 30 and the fluorescent molecule layer 40. The thickness of the substrate 10 is not limited and is set according to actual needs. The shape of the substrate 10 is also not specifically limited and is set according to actual needs. In this embodiment, the material of the substrate 10 is selected as silicon dioxide, which is convenient for detecting circularly polarized luminescence on the lower side of the entire device.

[0030] In this embodiment, the number of layers of the graphene layer 20 is greater than 4 and less than 10. The graphene layer 20 not only has the function of limiting the chiral electromagnetic field, but also changes its own dielectric constant under the action of the external magnetic field, thereby changing the chiral field between the first nanowire 31, the second nanowire 32, the first nanorod 33, and the second nanorod 34 from another angle. When the magnetic field is perpendicular to the graphene layer 20, the dielectric constant of the graphene layer 20 can be expressed as the following tensor:

[0031]

[0032] Wherein, t is the effective thickness of the graphene layer 20, ω is the angular frequency, ε0 ​​is the vacuum dielectric constant, σ d Independent of the external magnetic field σ d =σ xx (B=0).

[0033] In addition, a circular current is formed in the area surrounded by the first nanowire 31, the second nanowire 32, the first nanorod 33, and the second nanorod 34, that is, a magnetic dipole mode whose direction is perpendicular to the surface of the structure. When an external magnetic field is applied, it is the magnetic field that is externally regulated, which is more likely to affect the intensity of the magnetic dipole, thereby achieving more sensitive regulation of circularly polarized luminescence.

[0034] In this embodiment, the structural layer 30 includes a first nanowire 31, a second nanowire 32, a first nanorod 33, a second nanorod 34, a first magnetostrictive material portion 35, and a second magnetostrictive material portion 36. Among them, the first nanowire 31, the second nanowire 32, the first nanorod 33, and the second nanorod 34 are all made of precious metal materials. The precious metal material used is gold in order to maintain good chemical stability. The materials of the first magnetostrictive material portion and the second magnetostrictive material portion are iron gallium or iron silicon boron or nickel. Under the action of the magnetic field, the first magnetostrictive material portion and the second magnetostrictive material portion are extended. Figure 2As shown, the length of the first nanowire 31 and the second nanowire 32 is the length of a periodic unit, that is, both ends of the first nanowire 31 and the second nanowire 32 are extended to the edge of the periodic unit. In this way, from the overall perspective of the device, the first nanowire 31 and the second nanowire 32 are respectively connected together. In addition, the first nanowire 31 and the second nanowire 32 are not arranged along the edge of the periodic unit, that is, there is a certain distance from the edge of the periodic unit, and the distance is greater than 100 nanometers. Preferably, the first nanowire 31 and the second nanowire 32 are symmetrically arranged on both sides of the side bisector of the periodic unit. There is a certain interval between the first nanowire 31 and the second nanowire 32. The vertical distance between the first nanowire 31 and the second nanowire 32 is 200nm-400nm. The first nanorod 33 and the second nanorod 34 are arranged between the first nanowire 31 and the second nanowire 32, and the length of the first nanorod and the second nanorod is 50nm-300nm. The width and height of the first nanowire 31 and the second nanowire 32 are the same. The first nanorod 33 and the second nanorod 34 are vertically arranged on the side of the first nanowire 31 close to the second nanowire 32, and the second nanorod 34 is vertically arranged on the side of the second nanowire 32 close to the first nanowire 31. Since the first nanowire 31 and the second nanowire 32 are parallel to each other, the first nanorod 33 and the second nanorod 34 are also relatively parallel, and the extension lines of the first nanorod 33 and the second nanorod 34 do not overlap. There is a gap between the first nanorod 33 and the second nanorod 34. In practical applications, the first nanorod 33 and the second nanorod 34 are exactly the same, and the heights of the first nanowire 31, the second nanowire 32, the first nanorod 33, and the second nanorod 34 are equal. Optionally, the length of the first nanorod 33 and the second nanorod 34 is 50nm-300nm, that is, the length of the first nanorod 33 and the second nanorod 34 is 3 / 4-1 / 4 of the distance between the first nanowire 31 and the second nanowire 32. Optionally, the width of the first nanorod 33 and the second nanorod 34 is 40nm-80nm. The width of the first nanorod 33 and the second nanorod 34 is set according to actual needs and is not specifically limited here. Optionally, the vertical distance between the first nanorod 33 and the second nanorod 34 is 20nm-120nm, that is, the width of the gap between the first nanorod 33 and the second nanorod 34 is any size between 20nm-120nm, and the gap between the first nanorod 33 and the second nanorod 34 is the displacement space of the first nanorod 33 and the second nanorod 34. In this way, Figure 2 In the figure, part of the first nanowire 31, the first nanorod 33, part of the second nanowire 32, and the second nanorod 34 form a chiral-shaped region. Under the irradiation of excitation light, a chiral field with different chirality is formed in and at the edge of the region. The chiral field excites the luminescent molecules in the fluorescent molecular layer 40 to emit light, and finally produces circularly polarized light.

[0035] In this embodiment, the first magnetostrictive material portion 35 is arranged on the side of the first nanorod 33 away from the second nanorod 34, and the second magnetostrictive material portion 36 is arranged on the side of the second nanorod 34 away from the first nanorod 33. That is to say, the first magnetostrictive material portion 35 and the second magnetostrictive material portion 36 are arranged on the outside of the first nanorod 33 and the second nanorod 34, respectively. The first magnetostrictive material portion 35 and the second magnetostrictive material portion 36 are in contact with the first nanorod 33 and the second nanorod 34, respectively. Preferably, the first magnetostrictive material portion 35 and the second magnetostrictive material portion 36 are not in contact with the first nanowire 31 and the second nanowire 32. Under the action of the external magnetic field, the first magnetostrictive material portion 35 and the second magnetostrictive material portion 36 are extended, squeezing the first nanorod 33 and the second nanorod 34, so that the first nanorod 33 and the second nanorod 34 move toward each other and approach each other, changing the chiral field in the above-mentioned region, changing the asymmetric factor of the circularly polarized luminescence, and realizing the regulation of the circularly polarized luminescence.

[0036] In this embodiment, the fluorescent molecular layer 40 includes chiral luminescent molecules. The fluorescent molecular layer 40 is coated on the side of the structural layer 30 and the graphene layer 20 away from the substrate 10. Under the excitation of linear polarized light, a chiral field is formed in the above region to excite the chiral molecules to emit light. The luminescent molecules in the fluorescent molecular layer 40 can be chiral rare earth complexes, chiral transition metal complexes, helicene derivatives, or axial chiral binaphthol derivatives.

[0037] Example 2

[0038] On the basis of Example 1, Figure 3 As shown, the third magnetostrictive material portion 37 and the fourth magnetostrictive material portion 38 are also included. The third magnetostrictive material portion 37 is arranged on the side of the first nanowire 31 away from the second nanowire 32, and the fourth magnetostrictive material portion 38 is arranged on the side of the second nanowire 32 away from the first nanowire 31. That is, the third magnetostrictive material portion 37 and the fourth magnetostrictive material portion 38 are respectively arranged on the outside of the first nanowire 31 and the second nanowire 32. One side of the third magnetostrictive material portion 37 and the fourth magnetostrictive material portion 38 is in contact with the first nanowire 31 and the second nanowire 32, and the other side of the third magnetostrictive material portion 37 and the fourth magnetostrictive material portion 38 extends to the boundary of the periodic unit. Since the third magnetostrictive material portion 37 and the fourth magnetostrictive material portion 38 are added in the embodiment, the third magnetostrictive material portion 37 and the fourth magnetostrictive material portion 38 are extended under the action of the magnetic field, thereby squeezing the first nanowire 31 and the second nanowire 32, that is, on the basis of reducing the distance between the first nanorod 33 and the second nanorod 34, the distance between the first nanowire 31 and the second nanowire 32 is further reduced, thereby further changing the chiral field in the above-mentioned region, and regulating the circularly polarized luminescence with higher sensitivity.

[0039] Furthermore, the distance between the first nanorod 33 and the second nanowire 32, and the distance between the second nanorod 34 and the first nanowire 31 are both less than 40 nanometers. When the third magnetostrictive material portion 37 and the fourth magnetostrictive material portion 38 are extended, the coupling between the first nanorod 33 and the second nanowire 32 and between the second nanorod 34 and the first nanowire 31 can be more significantly changed, and the chiral field in the above region can be more significantly changed, so as to achieve more sensitive circularly polarized light emission regulation.

[0040] Example 3

[0041] On the basis of Example 2, Figure 4 As shown, the device also includes a second graphene layer 50, which is arranged on the side of the fluorescent molecule layer 40 away from the substrate 10. The number of graphene layers in the second graphene layer 50 is 1-8 layers. The second graphene layer 50 localizes the electromagnetic field in the above-mentioned area, so that a stronger chiral field is generated in the above-mentioned area. When the external magnetic field changes, the chiral field in the above-mentioned area is also changed more greatly, thereby achieving more sensitive circularly polarized luminescence regulation.

[0042] Example 4

[0043] On the basis of Example 3, Figure 5 As shown, the structural layer 30 also includes a third nanorod 60, which is vertically arranged on the side of the first nanowire 31 close to the second nanowire 32, and the extension lines of the first nanorod 33, the second nanorod 34 and the third nanorod 60 do not overlap. That is, the first nanorod 33 and the third nanorod 60 are respectively arranged on one side of the first nanowire 31, and only the second nanorod 34 is arranged on one side of the second nanowire 32. Under the action of the external magnetic field, the third magnetostrictive material part 37 and the fourth magnetostrictive material part 38 are extended, which not only reduces the distance between the first nanorod 33 and the second nanowire 32, the distance between the second nanorod 34 and the first nanowire 31, but also reduces the distance between the third nanorod 60 and the second nanowire 32. When the distance between the third nanorod 60 and the second nanowire 32 is reduced, the surface plasmon resonance on the first nanowire 31 and the second nanowire 32 is changed, thereby changing the chiral field in the above-mentioned area, thereby achieving a more sensitive circularly polarized luminescence regulation.

[0044] Furthermore, the distance between the free end of the third nanorod 60 and the second nanowire 32 is less than 40 nanometers, the distance between the third nanorod 60 and the second nanorod 34 is less than 200 nanometers, and more preferably, the distance between the third nanorod 60 and the second nanorod 34 is less than 100 nanometers. In this way, when the third nanorod is moved, the surface plasmon resonance in the first nanowire 31 and the second nanowire 32 can be significantly changed, so that the chiral field in the above region can be more significantly changed, and circularly polarized light emission regulation with higher sensitivity can be achieved.

[0045] Example 5

[0046] Based on any of the above embodiments, the first nanowire 31 and the second nanowire 32 are inclined, and the cross sections of the first nanowire 31 and the second nanowire 32 are inclined inward. This facilitates the collection of chiral electromagnetic fields between the first nanowire 31, the first nanorod 33, the second nanowire 32, and the second nanorod 34, and realizes circularly polarized light emission with a higher asymmetry factor on one side of the substrate 10.

[0047] Example 6

[0048] On the basis of Example 5, the material of the substrate 10 is silicon. Silicon material has a higher refractive index, which is convenient for forming a strong electromagnetic field concentration and a strong chiral field between the substrate 10 and the structural layer 30, thereby increasing the asymmetric factor of the circularly polarized luminescence. When the external magnetic field changes, a higher sensitivity of circularly polarized luminescence regulation can be achieved.

[0049] Furthermore, the heights of the first nanowire 31, the second nanowire 32, the first nanorod 33, and the second nanorod 34 are not equal, the asymmetry of the structure increases, and thus the chirality of the structure increases, which increases the difference in the intensity of the generated chiral field and leads to an increase in the circularly polarized luminescence signal.

[0050] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A device for regulating circularly polarized light emission, characterized in that: The device comprises: a substrate, a graphene layer, a structural layer and a fluorescent molecule layer; wherein the structural layer comprises a plurality of periodically arranged structural parts, each of which comprises: a first nanowire, a second nanowire, a first nanorod, a second nanorod, a first magnetostrictive material part and a second magnetostrictive material part; the graphene layer is arranged on one side of the substrate, the first nanowire and the second nanowire are arranged parallel to each other on a side of the graphene layer away from the substrate, the first nanorod is vertically connected to a side of the first nanowire close to the second nanowire, the second nanorod is vertically connected to a side of the second nanowire close to the first nanowire, the extension lines of the first nanorod and the second nanorod do not overlap, and a loop current is formed in a region surrounded by the first nanowire, the second nanowire, the first nanorod and the second nanorod; the first magnetostrictive material part is arranged on a side of the first nanorod away from the second nanorod, the second magnetostrictive material part is arranged on a side of the second nanorod away from the first nanorod, the first magnetostrictive material part and the second magnetostrictive material part are not in contact with the first nanowire and the second nanowire, and the fluorescent molecule layer is coated on the surface of the structural layer and the graphene layer away from the substrate.

2. The device for regulating circularly polarized light emission according to claim 1, characterized in that: The materials of the first nanowire and the second nanowire are noble metals.

3. The device for regulating circularly polarized light emission according to claim 1, characterized in that: The materials of the first nanorods and the second nanorods are noble metals.

4. The device for regulating circularly polarized light emission according to claim 1, characterized in that: The first magnetostrictive material portion and the second magnetostrictive material portion are made of iron gallium, iron silicon boron or nickel.

5. The device for regulating circularly polarized light emission according to claim 1, characterized in that: The material of the substrate is silicon.

6. The device for regulating circularly polarized light emission according to claim 1, characterized in that: The vertical distance between the first nanowire and the second nanowire is 200nm-400nm.

7. The device for regulating circularly polarized light emission according to claim 6, characterized in that: The lengths of the first nanorod and the second nanorod are 50 nm-300 nm.

8. The device for regulating circularly polarized light emission according to claim 7, characterized in that: The width of the first nanorod and the second nanorod is 40nm-80nm.

9. The device for regulating circularly polarized light emission according to claim 8, characterized in that: The vertical distance between the first nanorod and the second nanorod is 20 nm-120 nm.

10. The device for regulating circularly polarized light emission according to any one of claims 1 to 9, characterized in that: The first nanowire, the second nanowire, the first nanorod, and the second nanorod have the same height.

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