CN210072117U

CN210072117U - Nanowire grid structure and fluorescence anisotropy enhancement device

Info

Publication number: CN210072117U
Application number: CN201920672709.4U
Authority: CN
Inventors: 韩春蕊; 齐月静; 王宇; 叶剑挺
Original assignee: Institute of Microelectronics of CAS
Current assignee: Institute of Microelectronics of CAS
Priority date: 2019-05-10
Filing date: 2019-05-10
Publication date: 2020-02-14
Anticipated expiration: 2029-05-10

Abstract

The utility model provides a wire grid structure of nanometer and fluorescence anisotropy reinforcing means. The nano wire grid structure is formed by arranging a plurality of strip-shaped wire grids in parallel, and the structural parameters are as follows: the period of the wire grid is 300-800 nm, and the width of the wire grid is 50-400 nm. The device utilizes superstrong local area field and the super little mode volume that metamaterial surface plasmon resonance produced, and the spontaneous radiance and the fluorescence intensity of reinforcing fluorescent material modulate fluorescence reinforcing degree through the line width modulation of adjusting nanometer wire grid structure to through the cycle control fluorescence field reinforcing direction of adjusting nanometer wire grid structure, thereby solved that current material fluorescence signal is weak and prior art is difficult to modulate fluorescence reinforcing degree and light field polarization direction's technical problem.

Description

Nanowire grid structure and fluorescence anisotropy enhancement device

Technical Field

The utility model relates to the technical field of nano materials and nano photoelectron, in particular to a nano wire grating structure and a fluorescence anisotropy enhancing device.

Background

The micro-nano light source with controllable intensity has important application value in the aspects of signal generation, information transmission, monomolecular illumination, high-sensitivity sensing, cell nondestructive detection and the like, and is the key point of the research of the photon integration technology. The novel two-dimensional crystal which is started in recent years has wide forbidden band selectivity, covers the whole spectrum range from ultraviolet to infrared, and has the excellent characteristics of a monoatomic layer structure, mechanical stability, photoelectric adjustability, CMOS process compatibility and the like. But the practical application of the two-dimensional crystal as a micro-nano light source is limited by the weak spontaneous emission fluorescence.

There are various ways to achieve fluorescence enhancement. Chemically, fluorescence is enhanced by a fluorescence synergist, which can be covalently or non-covalently combined with a substance with weak fluorescence to form a fluorescent complex, thereby increasing the effective absorption cross section to enhance fluorescence, but the enhancement degree and direction cannot be controlled. Physically, in an electroluminescent system, the fluorescence intensity can be improved by increasing the bias current by increasing the forward bias of the PN junction, but as the forward bias increases, the barrier region becomes smaller, the PN junction disappears, and the fluorescence also disappears. In the photoluminescence system, the most direct means is to increase the fluorescence intensity by increasing the power of the excitation light, but the fluorescence intensity rapidly approaches saturation as the power of the excitation light increases, limited by the light absorption capacity of the material.

In view of this limitation, various optical resonant cavities have been studied, because the resonant cavity can change the medium environment of the fluorescent material, increase the photon local state density, and thus change the spontaneous emissivity of the material. The fluorescence spontaneous emission enhancement effect is physically described by the Purcell effect, where Purcell factor Fp is the most direct physical quantity of the expression enhancement effect.

Q on the right of the formula is the quality factor, which depends on the resonant mode linewidth and V is the mode volume. The larger Q and the smaller V, the more significant the fluorescence enhancement is with the larger Fp. Over time, optical resonant cavities have evolved from distributed bragg reflector cavities, microdisc resonant cavities, whispering gallery resonant cavities, photonic crystal resonant cavities to the forefront of metal surface plasmon resonant cavities. The resonant cavity material is conventionalThe dielectric evolves to metal and the resonant mode becomes smaller and smaller, from initially larger than the wavelength of light to close to the wavelength to now a few nanometers. A representative group has reported a method for controlling the spontaneous emission of quantum dots by photonic crystals in Peter Lodahl 2004, and points out that the main reason of the fluorescence enhancement is that the radiation lifetime of fluorescent materials is changed by the photonic crystal structure.

The appearance of metamaterials indicates that photonic devices can be free from the limit of optical diffraction and develop towards infinite miniaturization. The metal nano-structure metamaterial becomes an important technical means for fluorescence enhancement and modulation due to the ultra-strong electromagnetic field enhancement and local capability and the diversity and flexibility of the structure. Due to the ultra-small optical resonance mode volume, the Purcell factor is remarkably improved, so that the fluorescence spontaneous radiance is remarkably enhanced. In 2015, researchers at northwest university of the united states produced nano disc matrices of silver directly on the surface of a molybdenum disulfide monolayer and found a 12-fold increase in fluorescence intensity. By adjusting the disc diameter, the fluorescence shows different enhancement effects at different wavelengths. And indicates that the fluorescence enhancement is the result of the coupling of the surface plasmon resonance mode with the excitation field and the radiation field. In the same year, the research group of American university of Pennsylvania prepares the triangular bow-tie metal nanostructure on the surface of a molybdenum disulfide monolayer, and the two are in direct contact, so that the fluorescence intensity is improved by up to thirty times. By adjusting the period of the bow-tie structure, fluorescence also appears to be enhanced to different degrees at different wavelengths.

In conclusion, the research describes and explains the phenomenon and mechanism of two-dimensional crystal fluorescence enhancement, but the research on the metamaterial fluorescence modulation technology from the application point of view is not carried out, and particularly, the specific research on the fluorescence anisotropy enhancement technology is not carried out, so that the development of a fluorescence anisotropy enhancement device capable of being practically applied based on the surface plasmon metamaterial is necessary.

SUMMERY OF THE UTILITY MODEL

The main objective of the present invention is to provide a nano wire grid structure and fluorescence anisotropy enhancing device, which utilizes the super-strong local field and super-small mode volume generated by the surface plasmon resonance of the metamaterial to enhance the spontaneous radiance and fluorescence intensity of the fluorescent material, and modulate the fluorescence enhancing degree by adjusting the line width of the nano wire grid structure; the method has the advantages that the anisotropic fluorescence field is generated by utilizing the anisotropic resonance mode of the metamaterial, the field enhancement direction and the wavelength position are controlled by adjusting the period of the nano wire grid structure, and the method has the characteristics of simplicity, high efficiency and adjustability, so that the technical problems that the fluorescence signal of the existing material is weak and the fluorescence enhancement degree and the light field polarization direction are difficult to modulate in the prior art are solved.

To achieve the above object, according to a first aspect of the present invention, there is provided a nanogrid structure.

The nano wire grid structure is formed by arranging a plurality of strip-shaped wire grids in parallel, and the structural parameters are as follows: the period of the wire grid is 300-800 nm, and the width of the wire grid is 50-400 nm.

Further, the thickness of the plurality of bar-structured wire grids is 40-60 nanometers.

Further, the material of the plurality of bar-structured wire grids is a metal nano-structured metamaterial, and the metal nano-structured metamaterial is a gold, silver or aluminum material.

In order to achieve the above object, according to a second aspect of the present invention, there is provided a fluorescence anisotropy enhancing apparatus.

The fluorescence anisotropy enhancing device comprises a high-conductivity substrate, an insulating layer, a fluorescent layer, a light-transmitting medium layer and a nano wire grid structure which are sequentially arranged from bottom to top, wherein the nano wire grid structure is the nano wire grid structure.

Further, the high-conductivity substrate is a metal or a highly doped silicon substrate.

Further, the insulating layer is a silicon dioxide layer.

Further, the fluorescent layer is a single-layer two-dimensional semiconductor.

Further, the single layer of the two-dimensional semiconductor is an atomic layer of a transition metal chalcogenide represented as MX₂Wherein M ═ Mo or W; x is S, Se, Te; the thickness of the single-layer two-dimensional semiconductor is 0-0.6 nanometer.

Further, the light-transmitting medium layer is an aluminum oxide or silicon dioxide layer, and the thickness of the light-transmitting medium layer is 10-40 nanometers.

Further, the fluorescent layer is an organic fluorescent dye layer; the light-transmitting medium layer is a polymethyl methacrylate layer.

The physical mechanism of the fluorescence anisotropy enhancement of the utility model is metamaterial anisotropy surface plasmon resonance. Surface plasmon resonance is the collective resonance behavior of metal surface electrons induced by light; anisotropic resonance refers to the resonance of an electromagnetic field in a particular direction. As long as the incident light has the electric field component parallel or vertical to the nano wire grid, the anisotropic resonance behavior of the nano wire grid can be excited, and the fluorescence signal in the corresponding direction is enhanced. Therefore, the fluorescence anisotropy enhancing device of the present invention can not only enhance fluorescence, but also control the enhancement degree and direction.

In addition to the anisotropic enhancement, the fluorescence anisotropic enhancement device of the present invention can also generate anisotropic suppression of fluorescence signals. The metamaterial is integrated above the fluorescent material, under the normal condition, the fluorescence is shielded by the metal structure, and the shielding effect is in direct proportion to the metal area. However, when the metamaterial generates reflection resonance, the reflection enhancement effect is dominant to generate a super-strong fluorescence suppression effect, and then the shielding effect of the metal is not in direct proportion to the area of the metal. For example, fluorescence can be completely blocked by the metal structure in case of perfect reflection, resulting in perfect fluorescence suppression. The fluorescence suppression is also directional due to the strong reflection of the nanogrid generated in a specific axial direction.

The utility model discloses in, the anisotropic fluorescence light source of the integrated production of nano-structure metamaterial and two-dimensional crystal will be at nanometer light sensing, high-resolution formation of image, and biological structure detection area plays important role. For example, the fluorescent signal enhancement in a special electric field direction can cause the scattering signal of a certain structure in the molecule to be amplified and sensitively detected, which is helpful for the precise analysis of the molecular structure and provides a novel technical means for medical diagnosis and drug development. The anisotropic fluorescence enhancement is used in an illumination and signal detection system, so that the resolution of an imaging system can be improved, a clearer cell tissue image can be shot, more accurate tissue structure change information can be obtained, and a basis is provided for the disease condition diagnosis and rehabilitation process. The fluorescence anisotropy enhancement method provided by the utility model can inject new activity for single molecule detection and biomedical research.

The fluorescence anisotropy enhancing device in the utility model has the following advantages:

(1) the fluorescence field enhancement effect in the vertical direction can be generated along the axial direction of the metamaterial;

(2) the fluorescence signal can be enhanced to different degrees along different axial directions of the metamaterial;

(3) the fluorescent signals can be inhibited to different degrees in different axial directions of the metamaterial;

(4) the fluorescence enhancement and inhibition effects can be continuously modulated by structural parameters;

(5) has stronger controllability and practicability.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1a is an embodiment of the present invention showing silver nanogrid-WS₂A single-layer integrated device structure schematic diagram;

fig. 1b is an SEM image of a silver nanowire grid structure according to an embodiment of the present invention (period p is 400 nm, line width w is 150 nm);

fig. 1c is an SEM image of a silver nanowire grid structure according to an embodiment of the present invention (period P is 600 nm, line width w is 300 nm);

FIG. 2a is an embodiment of the present invention showing silver nanogrid-WS₂Optical microscopic imaging of a single-layer integrated device (the period p is 400 nanometers, and the line width w is 150 nanometers);

FIG. 2b is an embodiment of the present invention showing silver nanogrid-WS₂A single-layer integrated device TE direction fluorescence imaging (the period p is 400 nanometers, the line width w is 150 nanometers);

FIG. 2c is an embodiment of the present invention showing silver nanowire grid-WS₂The method comprises the following steps of (1) performing TM direction fluorescence imaging on a single-layer integrated device (the period p is 400 nanometers, and the line width w is 150 nanometers);

fig. 3a shows a polarization-resolved fluorescence spectrum in an embodiment of the present invention (period p is 400 nm, linewidth w is 150 nm); wherein, curve No. 1: single layer WS₂Fluorescence spectrum in the TE direction; curve 2: single layer WS₂Fluorescence spectrum in the TM direction; curve 3: silver nanogrid-WS₂TE direction fluorescence spectrum of the single-layer integrated device; curve 4: silver nanogrid-WS₂A single-layer integrated device TM direction fluorescence spectrum;

FIG. 3b is an embodiment of the present invention showing silver nanogrid-WS₂A single-layer integrated device TE and TM directional fluorescence enhancement curve (the period p is 400 nanometers, the line width w is 150 nanometers);

FIG. 4a is an embodiment of the present invention showing silver nanogrid-WS₂Optical microscopic imaging of a single-layer integrated device (the period p is 600 nanometers, and the line width w is 300 nanometers);

FIG. 4b is an embodiment of the present invention showing silver nanogrid-WS₂TE direction fluorescence imaging of a single-layer integrated device (the period p is 600 nanometers, and the line width w is 300 nanometers);

FIG. 4c is an embodiment of the present invention showing silver nanogrid-WS₂TM directional fluorescence imaging (cycle p 600 nm, linewidth w 300 nm) for single-layer integrated devices;

FIG. 5a is an embodiment of the present invention showing silver nanowire grid-WS shown in FIGS. 4 a-4 c₂Polarization-resolved fluorescence spectrum of a single-layer integrated device (the period p is 600 nanometers, and the line width w is 300 nanometers); wherein, curve 1: WS₂Single-layer TE direction fluorescence spectrum; curve 2: WS₂Single-layer TM direction fluorescence spectroscopy; curve 3: nanowire grids-WS₂Single-layer TE direction fluorescence spectrum; curve 4: nanowire grids-WS₂Single-layer TM direction fluorescence spectroscopy;

FIG. 5b is an embodiment of the present invention showing silver nanogrid-WS₂A TE direction fluorescence enhancement curve and a TM direction fluorescence enhancement curve of the single-layer integrated device (the period p is 600 nanometers, and the line width w is 300 nanometers);

FIG. 6 is the bookSilver nano wire grating-WS in the embodiment of utility model₂Single layer integrated device optical image and TE, TM direction fluorescence image analysis contrast diagram, wherein, first row: silver nanogrid-WS₂The single-layer integrated device optical image (the period p is 600 nanometers) has line widths w of 100 nanometers, 150 nanometers, 200 nanometers, 250 nanometers and 300 nanometers from left to right in sequence; a second row: with first row silver nanowire grid-WS₂A TE direction fluorescence image corresponding to a single-layer integrated device optical image (the period p is 600 nanometers); third row: with first row silver nanowire grid-WS₂A TM direction fluorescence image corresponding to a single-layer integrated device optical image (the period p is 600 nanometers);

FIG. 7 is a comparison graph of TE, TM directional fluorescence spectrum analysis in the embodiment of the present invention, wherein, in the first row: WS₂Single layer and silver nanogrid-WS₂A single-layer integrated device TE direction fluorescence spectrum with a period p of 600 nanometers; a second row: WS₂Single layer and silver nanogrid-WS₂The single-layer integrated device TM direction fluorescence spectrum has the period p of 600 nanometers.

In the figure:

1. a highly conductive substrate; 2. an insulating layer; 3. a fluorescent layer; 4. a light-transmitting medium layer; 5. a nanogrid structure; p, a wire grid period; w, wire grid width.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The utility model discloses a wire grid structure of nanometer, as shown in FIG. 1, this wire grid structure of nanometer is a plurality of bar structure wire grids parallel arrangement and forms, and its structural parameter is: the period of the wire grid is 300-800 nm, and the width of the wire grid is 50-400 nm.

Further, the thickness of the plurality of wire grids with the strip-shaped structures is 40-60 nanometers.

Further, the material of the plurality of bar-structured wire grids is a metal nano-structured metamaterial.

Further, the metallic nanostructured metamaterial is a gold, silver, or aluminum material.

Further, the metallic nanostructured metamaterial is a silver material.

In this embodiment, the nano-wire grid structure is formed by arranging a plurality of wire grids with strip structures in parallel, and the structural parameters are as follows: the wire grid period is 300-800 nm, the wire grid width is 50-400 nm, wherein the thickness of the plurality of strip structures is 40-60 nm, the raw material of the parallel strip structures is the metal nano structure metamaterial, and the metal nano structure metamaterial comprises any one of gold, silver or aluminum materials, as a preferred embodiment, the embodiment of the invention adopts the silver nano structure metamaterial. In the embodiment of the present invention, the period of the wire grid is between 300-800 nm, the width of the wire grid is between 50-400 nm, and the thickness of the plurality of wire grids with stripe structures is between 40-60 nm, so that the nano structure is suitable for adjusting the wavelength of the fluorescence signal in the visible light range.

The utility model discloses a fluorescence anisotropy enhancing device, as shown in fig. 1-3, this fluorescence anisotropy enhancing device includes high conductive substrate 1, insulating layer 2, fluorescent layer 3 and printing opacity dielectric layer 4 to and foretell nanometer wire grating structure 5, wherein the structure of device is high conductive substrate 1, insulating layer 2, fluorescent layer 3, printing opacity dielectric layer 4 and nanometer wire grating structure 5 from bottom to top in proper order.

In this embodiment, the fluorescence anisotropy enhancing device is a layered structure device, the bottom layer is a highly conductive substrate 1, an insulating layer 2 is disposed on the highly conductive substrate 1, the fluorescent layer 3 is disposed on the insulating layer 2, a transparent dielectric layer 4 is disposed on the fluorescent layer 3, the transparent dielectric layer 4 is used for isolating sensitive molecules, so as to improve the service life of the fluorescent material, and the nano wire grid structure 5 is disposed on the transparent dielectric layer 4.

Further, the highly conductive substrate 1 is a metal or highly doped silicon substrate.

Further, the insulating layer 2 is a silicon dioxide layer, and the material of the insulating layer 2 is silicon dioxide.

Further, the fluorescent layer 3 is a single-layer two-dimensional semiconductor.

Further, the light-transmitting medium layer 4 is an aluminum oxide or silicon dioxide layer with the thickness of 10-40 nanometers. The material of the light-transmitting medium layer 4 is aluminum oxide or silicon dioxide, the thickness is within the range of 10-40 nanometers, and the attenuation of the surface plasmon resonance field of the metamaterial on the metal surface is fast, so that the medium material is not suitable to be too thick.

As an embodiment, the fluorescent layer 3 is an organic fluorescent dye layer; the light-transmitting medium layer 4 is a polymethyl methacrylate layer.

By adopting the device and the method shown in the embodiment, the fluorescent layer 3 can also be made of organic fluorescent dye, the light-transmitting medium layer 4 is made of polymethyl methacrylate (PMMA), the organic fluorescent dye is doped into the PMMA, the mixture is uniformly mixed and coated on the silicon dioxide/silicon substrate 1 in a spin-coating manner, crosslinking and curing are carried out, and then the nano wire grid structure 5 is prepared on the PMMA, so that the fluorescence anisotropy enhancing device is obtained, and the fluorescence intensity can also be effectively enhanced and modulated.

The utility model discloses a preparation method of fluorescence anisotropy enhancing device, which comprises the following steps:

(1) growing a fluorescent layer on a high-conductivity substrate attached with a clean insulating layer by adopting a chemical vapor deposition method;

(2) a light-transmitting medium layer is vapor-plated on the fluorescent layer by adopting an electron beam coating instrument;

(3) preparing a periodic nano wire grid structure on the light-transmitting medium layer by adopting an electron beam direct writing technology, wherein part of the periodic nano wire grid structure is overlapped with the fluorescent layer;

(4) adopting positive electron beam glue to carry out nano wire grating structure exposure and structure transfer;

(5) filling metal into the positive adhesive structure through a metal coating film, and finally preparing the fluorescence anisotropy enhancing device through an adhesive removing process.

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings.

FIG. 1a is a silver nanowire grid-WS₂Single layer integrated device structure schematic diagram, silver nano wire grid-WS₂The structure of the single-layer integrated device comprises a silicon substrate and SiO from bottom to top in sequence₂Insulating layer, single layer WS₂、Al₂O₃A light-transmitting dielectric layer and a silver nano wire grid structure. The period p of the silver nanowire grid structure is between 300-800 nanometers, the line width w is between 50-400 nanometers, and both the period p and the line width w can be adjusted. The nano wire grid structure is prepared by adopting an electron beam direct writing technology, positive electron beam glue PMMA 950K is used for completing wire grid structure exposure and structure transfer, and finally the nano wire grid structure is prepared through metal coating and glue removing processes.

Fig. 1b is a Scanning Electron Microscope (SEM) image of a silver nano-wire grid structure with a period p of 400 nm and a line width w of 150 nm.

Fig. 1c is a Scanning Electron Microscope (SEM) image of a silver nano-wire grid structure with a period p of 600 nm and a line width w of 300 nm.

FIG. 2a is a silver nanowire grid-WS₂Single layer integrated device optical microscopy imaging, as can be seen in FIG. 2a, single layer WS₂The fluorescent layer is partially covered by silver nano wire grid (left side Ag + WS)₂Area) and partially leaked, the silver wire grid period p/line width w is 400/150 nanometers.

FIG. 2b is a silver nanowire grid-WS₂The method comprises the steps of performing TE direction fluorescence imaging on a single-layer integrated device, enabling the period p/line width w of a silver wire grid to be 400/150 nanometers, collecting a polarity-resolved fluorescence image through a fluorescence microscope, carrying an excitation light path, a side-band light filter and a high-sensitivity imaging CCD on a common optical microscope to form an imaging system, converging incident laser on a sample through a 100X objective lens for excitation, and collecting fluorescence signals. A polarizer is placed in front of the CCD to select the direction of fluorescence desired to be detected. As can be derived from fig. 2b, the areas covered by the silver nanowire grid structure have a strong light intensity, indicating that the silver nanowire grid structure acts to enhance the fluorescence signal.

FIG. 2c is a silver nanowire grid-WS₂The single-layer integrated device TM direction fluorescence imaging is characterized in that the period p/line width w of the silver wire grids is 400/150 nanometers, the light intensity of the area covered by the silver nano wire grid structure is obviously increased, the silver nano wire grid structure plays a role in enhancing fluorescence signals, and compared with TE direction fluorescence imaging in fig. 2b, the silver nano wire grid structure has a great enhancement effect on the TM direction fluorescence.

Fig. 3a shows polarization-resolved fluorescence spectroscopy, polarization resolution being achieved by placing a polarizer in front of the spectrometer entrance slit. Wherein, the period p of the silver nano wire grid structure is 400 nm, the line width w is 150 nm, and the

curves

1 and 2 are respectively a single layer WS₂Fluorescence spectra in the TE and TM directions; curve 3 is silver nanowire grid-WS₂TE direction fluorescence spectrum of the single-layer integrated device; curve 4 is silver nanowire grid-WS₂TM direction fluorescence spectroscopy for single layer integrated devices.

From FIG. 3a, it can be analyzed that the two

curves

1 and 2 are substantially coincident, indicating no polarity of the emitted fluorescence; the curve No. 3 shows fluorescence peaks at 640 nm and 760 nm, corresponding to WS essentially₂The neutral excitons and defects of (1) emit light. For TE direction fluorescence spectra, at 640 nm, silver nanogrid-WS₂The fluorescence intensity of the single-layer integrated device is single-layer WS₂The fluorescence intensity is 1.3 times that of the silver nanowire grid structure, so that the fluorescence of the area covered by the silver nanowire grid structure is enhanced; silver nanogrid-WS at 760 nm₂Fluorescence intensity ratio WS of a Single-layer Integrated device₂The monolayer is slightly higher, which indicates that the fluorescence enhancement effect of the silver nanowire grid structure at the wavelength is weaker. It follows that in the direction parallel to the silver nanowire grid structure (TE direction), either exciton fluorescence or defect fluorescence can be enhanced by the silver nanowire grid structure with a period p of 400 nm, but the enhancement effect is not strong. For the fluorescence signal in the TM direction, curve No. 4 also shows fluorescence peaks at 640 nm and 760 nm, respectively, and at 640 nm, silver nanogrid-WS₂The fluorescence intensity of the single-layer integrated device is WS₂The fluorescence intensity of the single layer is 0.7 times, which shows that the metal structure inhibits the fluorescence intensity; silver nanogrid-WS at 760 nm₂Fluorescence intensity of the Single layer Integrated device is WS₂The single-layer fluorescence intensity is 7 times, which shows that the silver nano wire grid structure with the period p being 400 nanometers has a remarkable enhancement effect on the defect fluorescence in the TM direction. And figure 3a is in good agreement with the fluoroscopic image (figures 2 b-2 c).

FIG. 3b is a silver nanowire grid-WS₂The TE and TM directional fluorescence enhancement curves of the single-layer integrated device have a period p of 400 nm and a line width w of 150 nm, and fig. 3b represents the fluorescence enhancement effect, which is represented by a silver nanowire grid-WS₂Single layer integrated device and WS₂Ratio of the fluorescence intensity of the monolayers. As can be seen from the TM-direction fluorescence enhancement curve, the silver nanowire grid structure with the period p of 400 nm has a significant enhancement effect on TM polarization defect fluorescence, which is determined by the TM-direction surface plasmon resonance mode.

FIG. 4a is a silver nanowire grid-WS₂The optical microscopic imaging of the single-layer integrated device is characterized in that the period p of the silver nano wire grid structure is 600 nanometers, the line width w is 300 nanometers, and WS₂The monolayer was partially covered by the silver nanowire grid structure and partially leaked out.

FIG. 4b is a silver nanowire grid-WS₂In TE direction fluorescence imaging of the single-layer integrated device, the period p is 400 nm, the line width w is 150 nm, and it can be seen from fig. 4b that the fluorescence of the region covered by the silver nanowire grid structure is enhanced.

FIG. 4c is a silver nanowire grid-WS₂In the TM direction fluorescence imaging of the single-layer integrated device, the period p is 400 nm, the line width w is 150 nm, and it can be seen from fig. 4c that the fluorescence of the region covered by the silver nanowire grid structure is suppressed, and the fluorescence becomes very dark, which indicates that the suppression effect is very obvious.

FIG. 5a is the silver nanowire grid-WS shown in FIGS. 4 a-4 c₂Polarization-resolved fluorescence spectroscopy for single-layer integrated devices, wire grid p 600 nm, and w 300 nm. Polarization resolution is achieved by placing a polarizer in front of the spectrometer entrance slit. Wherein curves 1 and 2 are respectively WS₂Single-layer TE and TM direction fluorescence spectra; curve 3 is silver nanowire grid-WS₂TE direction fluorescence spectrum of the single-layer integrated device; curve 4 is silver nanowire grid-WS₂TM direction fluorescence spectroscopy for single layer integrated devices.

From FIG. 5a, it can be analyzed that the two

curves

1 and 2 are substantially coincident, indicating no polarity of the exiting fluorescence. The fluorescence peaks of curve No. 3 at 640 nm and 760 nm essentially correspond to WS₂The neutral excitons and defects of (1) emit light. At 640 nm, silver nanogrid-WS₂The fluorescence intensity of the single-layer integrated device is WS₂1.6 times the intensity of the monolayer fluorescence, at 740 nm, silver nanogrid-WS₂The fluorescence intensity of the single-layer integrated device is WS₂The single layer fluorescence intensity is 5.5 times (fig. 5b), which shows that neither exciton fluorescence nor defect fluorescence can be enhanced by the silver nano-grating structure with the period p of 600 nm in the direction parallel to the grating, and the enhancement effect is stronger than that of the silver nano-grating structure with the period p of 400 nm. Curve 4 also shows fluorescence peaks at 640 nm and 760 nm, and at 640 nm, silver nanogrid-WS₂The fluorescence intensity of the single-layer integrated device is WS₂The silver nano wire grid structure with the period p of 600 nanometers is 0.4 times of the single layer, so that the silver nano wire grid structure with the period p of 400 nanometers has a very high inhibition effect on a neutral exciton fluorescence field in a TM direction, and the inhibition effect is stronger than that of the silver nano wire grid structure with the period p of 400 nanometers. And silver nanogrid-WS₂Defect fluorescence peak of single-layer integrated device is shifted to 780 nm wavelength, intensity is compared with WS₂The monolayer was nearly doubled (fig. 5b), indicating that the enhancement effect of the silver nanowire grid structure with a period p of 600 nm on TM-direction-defect fluorescence field is weaker than that in TE-direction. And the above-mentioned spectral measurement result and the fluorescence imaging chart (fig. 4 b-4 c) are matched well.

FIG. 6 is a silver nanowire grid-WS₂Comparing the optical image of the single-layer integrated device with the TE and TM direction fluorescence image analysis, wherein the first row is a silver nanowire grid-WS with the period p being 600 nanometers₂And (3) performing optical microscopic imaging on the single-layer integrated device. For convenience of comparison, WS₂The monolayer portion was covered by a silver nanogrid structure (left side Ag + WS)₂Area), partially leak out. From left to right, the line width w of the silver nanowire grid is 100 nm, 150 nm, 200 nm, 250 nm and 300 nm in sequence. The second row is TE-direction fluorescence imaging, with enhanced fluorescence in the area covered by the silver nanowire grid structure. The third row is TM direction fluorescence imaging, area fluorescence covered by silver nanowire grid structureLight is suppressed and the suppression effect becomes more and more pronounced as the wire grid width w increases from left to right.

FIG. 7 is a comparison graph of TE, TM directional fluorescence spectrum analysis, wherein the first row is silver nanowire grid-WS with period p being 600 nm₂The TE direction fluorescence spectrum of the single-layer integrated device is acquired by adjusting the optical axis of the polaroid to be parallel to the long axis direction of the wire grid, and the two curves respectively represent WS₂Single layer and silver nanogrid-WS₂TE direction fluorescence spectrum of the single-layer integrated device. From the figure, it can be derived that silver nanogrid-WS for neutral exciton fluorescence increases with the width w of the wire grid from left to right₂Single layer integrated device compare WS₂The single-layer fluorescence intensity is respectively enhanced by 2.0, 1.5, 1.45, 1.4 and 1.3 times, and the enhancement effect is weakened in sequence. The second row is the TM direction fluorescence spectrum, which is collected by adjusting the exit axis of the polarizer to an angle perpendicular to the long axis of the wire grid. Two curves represent respectively WS₂Single layer and integrated device TM direction fluorescence spectra. From the figure, it can be seen that the silver nanogrid-WS increases from left to right with the width w of the wire grid for neutral exciton fluorescence₂Single layer integrated device compare WS₂The single-layer fluorescence intensity is respectively enhanced by 0.7, 0.5, 0.45, 0.4 and 0.32 times, the enhancement effect is weakened in sequence, and the fluorescence inhibition effect of the silver nano wire grid structure with the period p being 600 nanometers in the TM direction is gradually enhanced. Moreover, the results also indicate that the line width w of the silver nanowire grid structure can be continuously modulated for fluorescence enhancement and suppression effects.

In the embodiment, the metamaterial period p and the line width w are main structural parameters for regulating and controlling the frequency, the intensity and the direction of the surface plasmon resonance mode. Firstly, the direction of a surface plasmon resonance mode resonance electric field can be changed by changing the period p, so that metamaterials with different periods generate mutually vertical resonance fields at the same frequency, and the fluorescence spontaneous radiation enhancement in the vertical direction is realized; secondly, changing the line width w under the condition of determining the period p can enable the fluorescence signal to generate different degrees or continuous enhancement in the specific axial direction of the metamaterial, so that the fluorescence intensity is adjustable; thirdly, in order to adjust the fluorescence signals with different wavelengths, the period w of the metamaterial needs to be changed according to the fluorescence wavelength to change the surface plasmon resonance position, so that the overlapping of the resonance field and the fluorescence field is achieved, and the fluorescence enhancement signal is generated. For example, the fluorescence wavelength of the single layer of tungsten disulfide is near 630 nm, a wire grid structure with a period of 600-800 nm can be selected, so that anisotropic surface plasmon resonance is generated near 600-700 nm, and then the wire grid width is further adjusted, so that the metamaterial resonance field moves near the fluorescence wavelength, thereby continuously enhancing the fluorescence intensity.

In addition, in order to popularize and apply, the embodiment of the present invention adopts organic fluorescent dye as fluorescent material, forms fluorescent layer 3, mixes organic fluorescent dye into transparent medium PMMA, mixes evenly and spin-coats on silica/silicon substrate 1, cross-linking solidification, prepares nano wire grid structure 5 on PMMA again, obtains fluorescence anisotropy enhancing device, and it also can effectively strengthen and modulate fluorescence intensity (not shown).

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered by the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A nano wire grid structure is characterized in that the nano wire grid structure is formed by arranging a plurality of wire grids with strip structures in parallel, and the structure parameters are as follows: the period of the wire grid is 300-800 nm, and the width of the wire grid is 50-400 nm.

2. The wire grid structure of claim 1, wherein the plurality of wire grids of striped structure have a thickness of 40-60 nm.

3. The nanowire grid structure of claim 1, wherein the material of the plurality of wire grid bar structures is a metallic nanostructured metamaterial, and the metallic nanostructured metamaterial is a gold, silver, or aluminum material.

4. A fluorescence anisotropy enhancement device, comprising a highly conductive substrate (1), an insulating layer (2), a fluorescent layer (3), a light-transmitting medium layer (4) and a nanogrid structure (5) arranged in this order from bottom to top, and the nanogrid structure (5) is the nanogrid structure according to any one of claims 1 to 2.

5. The fluorescence anisotropy enhancement device according to claim 4, characterized in that the highly conductive substrate (1) is a metal or a highly doped silicon substrate.

6. The fluorescence anisotropy enhancement device according to claim 4, characterized in that the insulating layer (2) is a silicon dioxide layer.

7. The fluorescence anisotropy enhancement device according to claim 4, wherein the fluorescent layer (3) is a single-layer two-dimensional semiconductor.

8. The fluorescence anisotropy enhancement device according to claim 7, wherein the single layer of two-dimensional semiconductor is an atomic layer of a transition metal chalcogenide represented as MX₂Wherein M ═ Mo or W; x is S, Se, Te; the thickness of the single-layer two-dimensional semiconductor is 0-0.6 nanometer.

9. The fluorescence anisotropy enhancement device according to claim 4, wherein the light-transmitting medium layer (4) is an aluminum oxide or silicon dioxide layer with a thickness of 10-40 nm.

10. The fluorescence anisotropy enhancement device according to claim 4, characterized in that, the fluorescent layer (3) is an organic fluorescent dye layer; the light-transmitting medium layer (4) is a polymethyl methacrylate layer.