SPPs excitation structure, preparation method thereof and light field energy transmission method

Abstract

The invention discloses a structure for exciting SPPs, which comprises a silicon dioxide substrate, at least one nanometer micro disc is arranged on the upper surface of the silicon dioxide substrate, the nanometer micro disc comprises a metal disc, and a metal triangular bulge extending outwards is arranged at the outer edge of the metal disc; and a plurality of channels consisting of cuboid nano structures are formed on the surface of the metal disc. The invention further discloses a preparation method of the SPPs excitation structure and a light field energy transmission method of the SPPs excitation structure. According to the invention, SPPs can be effectively excited and controlled and excited on the nano size, accurate regulation and control of the transmission path of the SPPs are realized, a local electromagnetic field is enhanced, and meanwhile, the material has efficient light-substance interaction capability, so that further development of the SPPs in nano photonics and related application fields is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of nanophotonics, and in particular relates to a structure for exciting SPPs, a preparation method thereof, and a method for transmitting light field energy. Background Art

[0002] Surface Plasmon Polaritons (SPPs) refer to an electromagnetic mode that propagates along the metal surface when light waves (electromagnetic waves) are incident on the interface between metal and dielectric. Under the excitation of the external electromagnetic field, the conduction band electrons on the metal surface oscillate collectively, and the electromagnetic waves couple with the free electrons on the metal surface. It can confine the electromagnetic field within the nanometer range of the metal surface, breaking through the diffraction limit of traditional optics. It has broad application prospects in super-resolution nanolithography, high-density data storage, near-field optics and other fields, and is the physical basis of contemporary nanophotonics.

[0003] Traditional methods for exciting surface plasmons include grating coupling technology and prism coupling technology. Grating coupling technology uses grating vectors to correct the wave vector mismatch between free-space beam radiation and surface plasmon polaritons, thereby generating surface plasmons at the interface between metal and dielectric; prism coupling technology uses the evanescent wave propagating along the vertical direction of the reflection surface when the incident light is totally reflected at the interface between the medium and the metal with different dielectric properties, triggering free electron oscillations on the metal surface, thereby generating surface plasmons. However, the above methods usually rely on macroscopic structural modulation, and it is difficult to achieve precise control of nano-sized SPPs.

[0004] In addition, the excitation and transmission efficiency of SPPs are strongly affected by the properties of metal materials and their interaction with the medium. Factors such as the surface roughness, shape, and interface quality of the metal with the medium will significantly affect the propagation characteristics of SPPs. Therefore, the development of technologies that can accurately control the characteristics of SPPs at the nanoscale is the key to improving the efficiency of SPPs applications. Summary of the invention

[0005] To solve the above problems, the purpose of the present invention is to provide a structure for exciting SPPs and a preparation method thereof and a method for transmitting light field energy, which can effectively excite and control the excitation of SPPs at the nanometer size, realize precise regulation of the SPPs transmission path, enhance the local electromagnetic field, and at the same time have efficient light-matter interaction capabilities, thereby promoting the further development of SPPs in nanophotonics and related application fields.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] A structure for exciting SPPs comprises a silicon dioxide substrate, wherein at least one nano-microdisk is arranged on the upper surface of the silicon dioxide substrate, wherein the nano-microdisk comprises a metal disk, wherein the outer edge of the metal disk has a metal triangular protrusion extending outwards; and a multi-channel composed of a rectangular nanostructure is formed on the surface of the metal disk.

[0008] Furthermore, the nano-micro-disks are disposed on the surface of the silicon dioxide substrate by focused ion beam etching technology.

[0009] A method for preparing a structure for exciting SPPs comprises the following steps:

[0010] S1. Substrate preparation: First, the silicon dioxide substrate is roughly polished, and then the silicon dioxide substrate is finely polished;

[0011] S2, photoresist coating: first, a layer of positive photoresist is uniformly coated on the surface of the silicon dioxide substrate treated in step S1, and then soft baking is performed to ensure that the photoresist is fully cured; then, a second layer of photoresist is coated to form a photoresist film;

[0012] S3, electron beam lithography: the photoresist film in step S2 is exposed layer by layer for several times, developed and thin-layer metal deposited until all the design patterns are completely formed;

[0013] S4, development: the photoresist substrate exposed by the electron beam in step S3 is developed several times, and after each development, the pattern depth and quality are detected by AFM or SEM;

[0014] S5, metal deposition: using an electron beam evaporator to perform metal deposition on the substrate in step S4 several times, and performing low-temperature annealing after each deposition;

[0015] S6. Peeling: First, the substrate in step S4 is initially peeled using low-intensity ultrasound, and the ultrasound intensity is gradually increased to perform several peelings to achieve progressive peeling and obtain a structure that excites SPPs.

[0016] Furthermore, in the above-mentioned step S1, first, the silicon dioxide substrate is coarsely polished using a polishing machine, using a grinding liquid with a particle size of 100 to 200 nm, a grinding pressure of 5 to 10 psi, a speed of 100 to 150 rpm, and a time of 15 to 30 min; then, fine polishing is performed using a polishing machine, using an ultrafine silica gel aqueous solution with a particle size of 10 to 50 nm, the grinding pressure is reduced to 1 to 3 psi, the speed is 200 to 300 rpm, and the time is 10 to 32 min, so that the surface roughness of the silicon dioxide substrate is less than 0.5 nm.

[0017] Furthermore, in the above step S1, the grinding liquid is a silica gel aqueous solution, aluminum oxide Al2 O 3 Or boron nitride BN nanoparticle solution.

[0018] Furthermore, in the above-mentioned step S2, first, a layer of positive photoresist is uniformly coated on the upper surface of the silicon dioxide substrate treated in step S1, and a spin coater is used to rotate at a speed of 4000-5000 rpm for 60-120 seconds, and soft-baked at 180-220°C for 90-180 seconds; then, a second layer of photoresist is coated, and the same spin coating and soft baking steps are repeated to form a photoresist film with a thickness of 3-10um.

[0019] Furthermore, in the above step S3, first, the photoresist film in step S2 is exposed using an electron beam lithography system, with the acceleration voltage set to 100-150 kV and the exposure dose set to 300-400 μC / cm 2 , define the first layer pattern; after the exposure is completed, develop it immediately, use the developer to develop for 60 to 100 seconds, and wash it with deionized water after development; then, carry out thin layer metal deposition, use electron beam evaporator to deposit 10 to 30nm Au film at a rate of 0.1 to 0.5nm / s; repeat the above operation process several times, exposing, developing and depositing layer by layer until all the design patterns are completely formed.

[0020] Furthermore, in the above-mentioned step S4, first, the photoresist substrate exposed by the electron beam in step S3 is immersed in a developer and developed for 30 to 45 seconds; after development, the substrate is rinsed with deionized water and a preliminary inspection is performed on an AFM or SEM; based on the inspection results, if uneven pattern depth or defects are found, at least one more development is performed, and cleaning and inspection are performed after development, and the development time for each time is controlled to be 10 to 15 seconds.

[0021] Furthermore, in the above step S5, an electron beam evaporator is used to perform metal deposition on the substrate in step S4, and a 10-15 nm gold film is deposited each time, and the deposition rate is 0.1-0.5 nm / s; after each deposition is completed, the substrate is transferred to a low-temperature annealing furnace and annealed at 100-150° C. for 10-20 min; the above operation process is repeated several times until the total metal layer thickness reaches 100-500 nm.

[0022] Furthermore, in the above step S6, first, the substrate in step S4 is placed in an ultrasonic cleaning machine, the ultrasonic intensity is set to 10-20W, and immersed in an organic solvent for 5-10 minutes; then, the ultrasonic intensity is gradually increased every 1-3 minutes, and each intensity is increased by 5-8% over the previous intensity.

[0023] A method for exciting SPPs by transmitting light field energy through a structure includes a laser, a nano-microdisk array, and a spectrometer for receiving signals. The nano-microdisk array is arranged on the surface of a silicon dioxide substrate. Broadband laser emitted by the laser irradiates the nano-microdisk array to excite surface plasmons. Sharp metal triangular protrusions on the nano-microdisks strengthen metal surface plasmons to achieve a light field convergence effect. Meanwhile, plasmons excited by metal disks of the nano-microdisks are transmitted between the metal disks through an evanescent field.

[0024] Due to the adoption of the above-mentioned technical solution, the present invention has the following advantages:

[0025] The structure for exciting SPPs uses a nano-microdisk structure that can effectively enhance the surface plasmons of metals; the multi-channel rectangular structure can effectively control and guide the transmission path of SPW, achieving efficient SPW transmission and control; the geometric shape of the structure and the choice of materials significantly enhance the local light field, making it suitable for high-sensitivity photoelectric detection.

[0026] The preparation method of the structure that excites SPPs significantly reduces the SiO 2 The surface roughness of the substrate is improved to improve the accuracy of subsequent processes; the resolution and etching resistance of the pattern are improved through double-layer photoresist coating and soft baking; the layer-by-layer exposure and development technology is adopted to effectively avoid the pattern blur caused by beam scattering in a single exposure, and significantly improve the resolution of the pattern; through gradual development and real-time detection, the development process is ensured to be uniform and the pattern is complete, avoiding excessive or insufficient development; the combination of fractional deposition and low-temperature annealing can reduce film stress and improve the crystallization quality and adhesion of the film; the use of progressive ultrasonic stripping technology can avoid pattern damage and metal shedding caused by one-time stripping, ensuring the integrity and safety of the stripping process.

[0027] This method of structural transmission of light field energy for exciting SPPs uses multiple nano-microdisks to achieve the transfer of light field energy between nano-microdisks; by focusing the transmission of surface plasmon waves on the tip of the nanotriangle, the power of light can be increased by an order of magnitude, which can be used to detect small molecules and realize real-time, integrated sensing on miniaturized chips; it has broad application potential and is suitable for multiple technical fields such as biosensing, optical data storage, subwavelength optics and lithography. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the method for realizing structural transmission of light field energy for exciting SPPs.

[0029] Figure 2 This is a numerical simulation diagram of the nano-microdisk strengthening metal SPPs through the metal triangular protrusion structure;

[0030] Figure 3 This is a numerical simulation diagram of the energy transfer of TE and TM mode SPPs light fields between two nano-microdisks;

[0031] Figure 4 This is a numerical simulation diagram of the energy transfer of TE and TM mode SPPs light fields between three nano-microdisks;

[0032] Figure 5 a. Figure 5 d is a schematic diagram of the simulation of a 500 nm gold nanodisk with a 50 nm gold triangle tip and a 50 nm zigzag gold triangle tip rod; Figure 5 b. Figure 5 e respectively Figure 5 a. Figure 5 d is an enlarged view of the area within the dashed box; Figure 5 c. Figure 5 f are shown respectively Figure 5 b. Figure 5 Energy intensity distribution diagram on the horizontal dashed line in e; Figure 5 g. Figure 5 h are scanning electron microscope (SEM) images of the gold nanodisk with a 50 nm gold triangle tip and a 50 nm zigzag gold triangle tip rod, respectively;

[0033] Figure 6 This is an experimental diagram of the strong near-field enhancement effect of the metal triangular protrusion structure of the nano-microdisk; Figure 6 a. Figure 6 d Scanning near-field optical microscopy (SNOM) images of the nano-microdisk with nano-triangles and nano-cuboid nano-triangles, respectively; Figure 6 b. Figure 6 e respectively show Figure 6 b. Figure 6 Experimental energy intensity distribution diagram on the horizontal dashed line in e; Figure 6 c. Figure 6 f respectively show the calculated energy intensity distribution on the horizontal dashed line in the simulation inset;

[0034] Figure 7 This is a diagram of the application of nanostructures with SPPs aggregation capability; Figure 7 a is a schematic diagram of detecting rhodamine 6G (R6G) at the triangular protrusions and edges of the nano-microdisk; Figure 7 b Scanning near-field optical microscopy (SNOM) images of the nanodisk with R6G at the triangular protrusion (point A) and edge (point B); Figure 7 c is Figure 7 The corresponding spectral signal diagram in b; Figure 7 d is Figure 7b Comparison of the stability of R6G fluorescence intensity at the triangular bulge (point A) and edge (point B);

[0035] In the figure: 1 - laser; 2 - nano-microdisk array; 3 - spectrometer. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0037] The following equipment is involved in the embodiment:

[0038] Chemical mechanical polisher, model Applied Materials Reflexion LK;

[0039] Spin coater, model: Laurell WS-650-23B spin coater;

[0040] Electron beam lithography system, model Raith EBPG 5200;

[0041] Electron beam evaporator, model: CHAIndustries SEC-00;

[0042] Developer, model SUSS MicroTec DEV200;

[0043] Electron beam evaporator (Ebeam Evaporator), model: CHAIndustries SEC600;

[0044] Ultrasonic Cleaner (Branson 5800).

[0045] A structure for exciting SPPs comprises a silicon dioxide substrate, wherein at least one nano-microdisk is arranged on the upper surface of the silicon dioxide substrate, wherein the nano-microdisk comprises a metal disk, wherein the outer edge of the metal disk has a metal triangular protrusion extending outward; a multi-channel composed of a rectangular nanostructure is formed on the surface of the metal disk; and the thickness of the nano-microdisk is 100-150 nm.

[0046] The nano-microdisks were placed on the surface of a silicon dioxide substrate by focused ion beam etching (FIB). Before etching, the surface of the silicon dioxide substrate was cleaned with 99% alcohol and ultrasonically cleaned using an ultrasonic cleaning device to remove any attached particles; a 100-nanometer-thick gold (Au) seed layer was then deposited on the substrate by a Pecs II system. The conductive gold seed layer served as a cathode in the subsequent electroplating step. Gold (Au) was selected as the preferred material because it can resist oxidation and maintain adhesion to SiO during nanomechanical testing. 2Strong adhesion of the substrate; then exposure was performed using a microscope system (ZEISS) with an accelerating voltage of 10 kV; during all exposure processes, the beam current was maintained between 50 and 100 nanoamperes, and the beam step size of the voltage was 1 nanometer; the surface metal was removed immediately by a wet etching method after exposure; all FIB images were generated using a 30 kV argon ion beam with a current of approximately 50 nanoamperes.

[0047] The nanostructures were characterized by scanning electron microscopy (SEM), FIB imaging, transmission electron microscopy, and small area electron diffraction (TEM and SAED, FEI Tecnai F20). Scanning electron microscopy (SEM) confirmed the geometry of the nano-microdisk structure to verify the lithography parameters; FIB imaging was mainly used to qualitatively judge the nanostructure. In the experiment, SNOMNtegraSpectra (NTMDT) was used to study the propagation of TM-polarized Gaussian beams of multi-line lasers with a wavelength of 350-950 nm (ComblasVIS, GLOphotoniccs for visible and UVA) through an amplitude ZP with chrome relief; then, the light was focused by a 100x objective lens and transmitted through a spectrometer S (SolarTIl, Nanofinder 30) to filter out irrelevant radiation, and finally recorded by a CCD camera.

[0048] The method for preparing the structure for exciting surface plasmons comprises the following steps:

[0049] S1. Substrate preparation: First, the silicon dioxide substrate is roughly polished, and then the silicon dioxide substrate is finely polished; the operation is as follows:

[0050] First, the silicon dioxide substrate is roughly polished using a polishing machine, using a silica gel aqueous solution with a particle size of 100 to 200 nm, aluminum oxide Al 2 O 3Or boron nitride BN nanoparticle solution to provide higher removal rate and reduce particle residue, the grinding pressure is 5-10psi, the speed is 100-150rpm, and the time is 15-30min; then, fine polishing is performed using a polishing machine, using an ultrafine silica gel aqueous solution with a particle size of 10-50nm, or a multi-component nano-composite polishing liquid, for example, a mixture of silica gel and titanium dioxide, to form a uniformly distributed two-component particle, further improving the surface smoothness; preferably, a passivator is added, the passivator includes but is not limited to ammonium fluoride and potassium hydroxide, which can reduce surface defects ; The grinding pressure is reduced to 1-3 psi, the speed is 200-300 rpm, and the time is 10-32 min; In addition, it is equipped with a dynamic pressure regulation and intelligent monitoring system to monitor and adjust the polishing pressure, temperature and uniformity in real time to ensure that the fine polishing stage gradually drops to a suitable grinding pressure so that the surface roughness of the silicon dioxide substrate reaches below 0.5 nm; In the above two polishing stages, the silicon dioxide substrate is cleaned with deionized water after polishing, and the surface quality is tested by atomic force microscopy (AFM) to ensure that the high-quality silicon dioxide substrate provides an excellent foundation for subsequent processes;

[0051] S2, photoresist coating: first, a layer of positive photoresist is uniformly coated on the surface of the silicon dioxide substrate treated in step S1, and then soft baking is performed to ensure that the photoresist is fully cured; then, a second layer of photoresist film is coated; the operation is as follows:

[0052] First, a layer of positive photoresist is uniformly coated on the upper surface of the silicon dioxide substrate treated in step S1, and the substrate is rotated at a speed of 4000-5000 rpm for 60-120 seconds using a spin coater, and soft-baked at 180-220° C. for 90-180 seconds to ensure that the photoresist is fully cured; then, a second layer of photoresist is coated, and the same spin coating and soft-baking steps are repeated to form a photoresist film with a thickness of 3-10 μm; the structure of the double-layer photoresist can improve the resolution and etching resistance of the pattern, and provides an excellent foundation for subsequent electron beam lithography and development processes;

[0053] Preferably, the positive photoresist is PMMA950kA4 positive photoresist;

[0054] S3, electron beam lithography: the photoresist film in step S2 is exposed layer by layer, developed and thin-layer metal deposited several times until all the design patterns are completely formed; the operation is as follows:

[0055] First, the photoresist film in step S2 is exposed using an electron beam lithography system (EBL) with an acceleration voltage of 100-150 kV and an exposure dose of 300-400 μC / cm 2, the beam current is 80-120pA, the focus size is 1-3nm, and the first layer pattern is defined; after the exposure is completed, development is immediately performed, and the developer is used for development for 60-100s, and after development, it is washed with deionized water to remove the undeveloped area, and the developer is a 1:3 solution of methyl isobutyl ketone (MIBK): isopropyl alcohol (IPA); then, a thin layer of metal is deposited, and an electron beam evaporator is used to deposit a 10-30nm Au film at a rate of 0.1-0.5nm / s; the above operation process is repeated several times, exposing, developing and depositing layer by layer until all the design patterns are completely formed, thereby effectively avoiding the pattern blur caused by beam scattering in a single exposure, and ensuring the high resolution and clarity of the pattern; the exposure pattern is a nano-microdisk with a diameter of 35-45nm;

[0056] S4, development: the photoresist substrate exposed by the electron beam in step S3 is developed several times. After each development, the pattern depth and quality are detected by AFM or SEM to ensure that the development process is uniform and the pattern is complete. The operation is as follows:

[0057] First, immerse the photoresist substrate exposed by electron beam in step S3 in a developer and develop for 30 to 45 seconds; after development, rinse the substrate with deionized water to remove the developer, and perform preliminary inspection on AFM or SEM to measure the pattern depth and quality; according to the inspection results, if the pattern depth is uneven or defective, perform at least one more development, and perform cleaning and inspection after development, and each development time is controlled within 10 to 15 seconds; through the above-mentioned staged development and real-time monitoring method, the uniformity of the development process and the integrity of the pattern can be ensured, and finally a high-resolution photolithography pattern can be achieved;

[0058] S5, metal deposition: using an electron beam evaporator to perform metal deposition on the substrate in step S4 several times, and performing low temperature annealing after each deposition to reduce stress and improve the crystal quality and adhesion of the film; the operation is:

[0059] The substrate in step S4 is subjected to metal deposition using an electron beam evaporator, with a gold film of 10 to 15 nm being deposited each time, a deposition rate of 0.1 to 0.5 nm / s, a substrate temperature of room temperature, and a vacuum degree of 1×10 -7 ~2×10 -7 Torr; after each deposition is completed, the substrate is transferred to a low-temperature annealing furnace and annealed at 100-150°C for 10-20 minutes to reduce the internal stress of the film, promote the crystallization process of the film and improve the adhesion; the above operation process is repeated several times until the required total metal thickness of 100-500nm is reached, ensuring that the metal film has excellent crystallization quality and good adhesion performance, thereby improving the optoelectronic performance of subsequent devices;

[0060] S6, peeling: First, the substrate in step S4 is initially peeled using low-intensity ultrasound, and the ultrasound intensity is gradually increased to perform several peelings to achieve progressive peeling and obtain a structure that excites SPPs; the operation is:

[0061] First, the substrate in step S4 is placed in an ultrasonic cleaning machine, the ultrasonic intensity is set to 10-20W, and immersed in an organic solvent for 5-10 minutes, the organic solvent includes but is not limited to ethyl acetate, acetone, isopropanol, ethanol, to start peeling the metal film; then, the ultrasonic intensity is gradually increased every 1-3 minutes, each intensity is increased by 5-8% over the previous intensity, and the peeling effect is observed to ensure that the metal film is gradually separated from the substrate without causing pattern damage or metal shedding; when it is observed that the metal film begins to be completely peeled off, the ultrasonic treatment is immediately stopped, and the substrate is cleaned with deionized water to remove the residue after peeling; through the above-mentioned progressive peeling method, the damage caused by one-time peeling can be effectively avoided, thereby maintaining the integrity of the pattern and the adhesion of the metal.

[0062] A method for exciting SPPs by transmitting a light field, comprising a laser 1, a nano-microdisk array 2, and a spectrometer 3 for receiving a signal, wherein the nano-microdisk array 2 is arranged on a surface of a silicon dioxide substrate, such as Figure 1 As shown; the broadband laser emitted by laser 1 irradiates the nano-microdisk array to excite surface plasmons. The sharp metal triangular protrusions on the nano-microdisks strengthen the metal surface plasmons and achieve the convergence effect of the light field. At the same time, the plasmons excited by the metal disks of the nano-microdisks are transmitted between the metal disks through the evanescent field.

[0063] Metal disks excite evanescent fields: When the SPPs of the metal are excited, an evanescent field is generated at the interface between the metal and the air. When different metal disks are close enough, the evanescent fields excited by different metal disks resonate and couple with each other. Through the interaction between the evanescent fields, the light field energy can be coupled from one metal disk to another, thereby realizing the transfer of light field energy between different metal microdisks.

[0064] Example 1

[0065] A nano-microdisk with a metal triangular protrusion extending outward is etched on a silicon dioxide substrate. The diameter of the microdisk is 1μm. The excitation light wavelength is 850nm and incident from the right to excite the surface plasmon of the metal. It can be found that the sharp corner position has a significant converging effect on light, similar to the lightning rod effect, such as Figure 2 shown.

[0066] When two microdisk structures are etched on a silicon dioxide substrate, the diameter of the microdisk is 1 μm, and the excitation light wavelength of 532 nm is incident from the right side to excite the surface plasmon of the metal; the evanescent fields of the two microdisk structures can resonate and couple, so that the light field energy can be transferred between the two, such as Figure 3 shown.

[0067] It can be seen that the nano-microdisk structure of the present invention can effectively strengthen the SPPs of the metal, and the light field energy can be well transmitted therein. When the number of nano-microdisk structures is increased to three, the light field transmission results are as follows: Figure 4 As shown, it can be seen that the light field energy can be well propagated therein.

[0068] exist Figure 2 , 3 4, SiO 2 Substrate represents silicon dioxide substrate, Metal Nanodisk represents metal nano-microdisk, Metal Nano-triangle represents metal triangular protrusion, and Incident light represents incident light.

[0069] Example 2

[0070] Two nano-microdisks with a distance of 50nm and a radius of 100nm can achieve efficient surface plasmon wave (SPW) transmission. The numerical simulation was designed using FDTD software, the surface of the nano-microdisk structure was detected by a monitor, and the boundary conditions were implemented using the perfect matching layer (PML) method. In the results, when light is irradiated, the power of the electromagnetic field at the focusing point at the bottom of the nano-microdisk structure is enhanced by 109.6 times and 21.4 times through the nano-triangular protrusions of the nano-microdisk and the cuboid nanostructure of the nano-microdisk, respectively, as shown in Figure 2. Figure 5 c. Figure 5 f.

[0071] In the present invention, the focused ion beam (FIB) etching technology is selected because the FIB technology has the ability to perform three-dimensional manufacturing, direct writing, low cost and wider material compatibility, which is the key factor in realizing the desired nanoscale structure. 2 A nanodisk with a diameter of 500 nanometers is etched on a prism substrate. In the numerical simulation of the FDTD software, 860 nanometers of TM polarized laser illumination is used. Figure 5 a. Figure 5 d shows the optical field energy distribution of a 500 nm metal nano-microdisk with a 50 nm metal triangle tip and a 50 nm zigzag metal triangle tip rod at the bottom layer; the incident light is focused to the tip by a prism under the nanostructure, and the corresponding optical field distribution is shown on the horizontal dashed line. Figure 5 c. Figure 5 f; The nano-microdisk structure can guide the incident light and focus it at the tip, such as Figure 5 d; the sample preparation was effectively completed by FIB technology, such as Figure 5 g. Figure 5 h. In order to evaluate the focusing effect, a SiO 2 Metal nanodisks with a diameter of 500 nanometers are engraved on the prism.

[0072] Test Case

[0073] Functional verification and application of the structure of the present invention to stimulate SPPs

[0074] Light field enhancement: SNOM technology has confirmed that nanostructures can significantly enhance local light fields after being irradiated with light.

[0075] Biosensing applications: Using nano-microdisk structures to monitor the interaction of biomolecules such as rhodamine 6G and protoporphyrin IX, and to improve the fluorescence intensity and sensitivity of molecular detection.

[0076] Optical Data Storage: Nanostructures’ ability to directionalize light propagation and control offers potential solutions for optical data storage technologies.

[0077] A scanning near-field optical microscope (SNOM, Ntegra Solaris of NTMDT) equipped with a laser source (GLOphotonics ComblasVIS) in the wavelength range of 350-950 nm was used to examine the characteristics of samples processed by the FIB process. Figure 6 a shows the energy field diagram of the nano-microdisk experiment with a tip, which shows the light field focusing phenomenon under the irradiation of a 1mW 350950nm wavelength band laser source; Figure 6 b shows Figure 6 Energy field distribution on the white dashed cross section in a. The relative light intensity at the tip of the nanotriangle of the nano-microdisk is 10.5, which is 4.2 times the light intensity of 2.5 at the edge of the nano-microdisk. Figure 6 The calculation results of c reveal that the light intensity at the corresponding tip is 109.6 and the edge intensity is 13.8, showing an enhancement of 7.9 times; Figure 6 d. Figure 6 e. Figure 6 f shows the corresponding experimental results of gold nano-microdisks and nano-cuboid nano-triangle structures under the same experimental conditions; Figure 6f, the corresponding simulation data show that the intensity of point E2 is 21.4 and the intensity of point C2 is 1.9, showing an enhancement of 11.3 times. By combining numerical simulation and experimental results, we are able to realize two nano-microdisk structures to achieve directional propagation and concentration of surface plasmon waves, thereby making it possible to focus light and enhance energy. In addition, the properties of these two nano-microdisk structures can be used to significantly enhance the interaction between light and matter. Therefore, the directional propagation and concentration of nano-microdisk structures can be effectively adapted to biosensing, for example, by enhancing the interaction between light and matter to detect and monitor the interaction of molecules and biomolecules.

[0078] According to the above content, it is known that the nano-microdisk structure of the present invention will enhance the interaction between light and matter to detect or monitor molecular interactions. To demonstrate the advantages of the present invention in detection and monitoring, we used the common fluorescent dye rhodamine 6G (R6G) and the common biomolecule protoporphyrin IX (PpIX) to measure the enhancement of fluorescence intensity and the monitoring of molecular interactions based on the interaction between light and matter. First, in the experiment, 10 microliters of 4.3×10 -17 g / ml of R6G solution, close to the single molecule concentration in the 10 μl dose used, e.g. Figure 7 Then, when a laser beam with a wavelength of 350950 nanometers illuminates the nano-triangle structure of the nano-microdisk structure, we measure the fluorescence intensity of points A and B on the nanostructure. Figure 7 As shown in a, point A is the tip of the nanotriangle, and point B is a point on the nano-microdisk; according to the detection results, due to the enhanced interaction between light and matter at the tip of the nanotriangle, the fluorescence intensity of R6G is enhanced compared with point B, as shown in Figure 7 b. Figure 7 Finally, the corresponding optical energy field of the nanodisk with R6G obtained using SNOM is shown in Figure 7 b. The fluorescence at point A is stronger, with a relative light intensity of 4.90, which is 2.59 times the light intensity of 1.89 at the edge of the nanodisk (point B). At the same time, we detected the fluorescence spectrum signals of R6G at the tip of the nanotriangle and the edge of the nanomicrodisk, respectively. Figure 7 c. The energy measured at point A is 2.85 times that at point B. Figure 7 As shown in d, the fluorescence intensity recorded at points A and B remained stable during ten experiments, indicating that the nano-microdisk structure of the present invention can reliably monitor single-molecule interactions.

[0079] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, all equivalent changes and modifications made within the scope of the patent application of the present invention shall fall within the scope of patent protection of the present invention.

Claims

1. A structure for exciting SPPs, characterized by: It includes a silicon dioxide substrate, on the upper surface of which is arranged at least one nano-micro-disk, the nano-micro-disk including a metal disk, the outer edge of which is provided with a metal triangular protrusion extending outwards; and the surface of the metal disk forms multiple channels composed of cuboid nano-structures.

2. The structure for exciting SPPs according to claim 1, characterized in that: The nano-micro-disk is arranged on the surface of the silicon dioxide substrate by using a focused ion beam etching technique.

3. A method for preparing a structure for exciting SPPs according to claim 1 or 2, characterized in that: It includes the following steps: S1. Substrate preparation: First, the silicon dioxide substrate is roughly polished, and then the silicon dioxide substrate is finely polished; S2, photoresist coating: first, a layer of positive photoresist is uniformly coated on the surface of the silicon dioxide substrate treated in step S1, and then soft baking is performed to ensure that the photoresist is fully cured; Then, a second layer of photoresist is coated to form a photoresist film; S3, electron beam lithography: the photoresist film in step S2 is exposed layer by layer for several times, developed and thin-layer metal deposited until all the design patterns are completely formed; S4, development: the photoresist substrate exposed by the electron beam in step S3 is developed several times, and after each development, the pattern depth and quality are detected by AFM or SEM; S5, metal deposition: using an electron beam evaporator to perform metal deposition on the substrate in step S4 several times, and performing low-temperature annealing after each deposition; S6. Peeling: First, the substrate in step S4 is initially peeled using low-intensity ultrasound, and the ultrasound intensity is gradually increased to perform several peelings to achieve progressive peeling and obtain a structure that excites SPPs.

4. The method for preparing a structure for exciting SPPs according to claim 3, characterized in that: In the step S1, first, the silicon dioxide substrate is coarsely polished using a polishing machine, using a grinding liquid with a particle size of 100 to 200 nm, a grinding pressure of 5 to 10 psi, a speed of 100 to 150 rpm, and a time of 15 to 30 min; then, fine polishing is performed using a polishing machine, using an ultrafine silica gel aqueous solution with a particle size of 10 to 50 nm, the grinding pressure is reduced to 1 to 3 psi, the speed is 200 to 300 rpm, and the time is 10 to 32 min, so that the surface roughness of the silicon dioxide substrate is less than 0.5 nm.

5. The method for preparing a structure for exciting SPPs according to claim 3, characterized in that: In the step S2, first, a layer of positive photoresist is uniformly coated on the upper surface of the silicon dioxide substrate treated in step S1, and a spin coater is used to rotate at a speed of 4000-5000 rpm for 60-120 seconds, and soft-baking is performed at 180-220° C. for 90-180 seconds; then, a second layer of photoresist is coated, and the same spin coating and soft-baking steps are repeated to form a photoresist film with a thickness of 3-10 um.

6. The method for preparing a structure for exciting SPPs according to claim 3, characterized in that: In the step S3, first, the photoresist film in step S2 is exposed to the first exposure using an electron beam lithography system, the acceleration voltage is set to 100-150 kV, the exposure dose is set to 300-400 μC / cm2, and the first layer pattern is defined; after the exposure is completed, development is immediately performed, using a developer for 60-100 s, and after development, it is washed with deionized water; then, a thin layer of metal is deposited, using an electron beam evaporator to deposit a 10-30 nm Au film at a rate of 0.1-0.5 nm / s; the above operation process is repeated several times, exposing, developing and depositing layer by layer until all the design patterns are completely formed.

7. The method for preparing a structure for exciting SPPs according to claim 3, characterized in that: In the step S4, first, the photoresist substrate exposed by electron beam in step S3 is immersed in a developer and developed for 30 to 45 seconds; After development, the substrate is rinsed with deionized water and a preliminary inspection is performed on the AFM or SEM. Based on the inspection results, if uneven pattern depth or defects are found, at least one more development is performed, followed by cleaning and inspection. The development time for each development is controlled within 10 to 15 seconds.

8. The method for preparing a structure for exciting SPPs according to claim 3, characterized in that: In the step S5, metal deposition is performed on the substrate in step S4 using an electron beam evaporator, with a gold film of 10 to 15 nm being deposited each time at a deposition rate of 0.1 to 0.5 nm / s; After each deposition is completed, the substrate is transferred to a low-temperature annealing furnace and annealed at 100-150° C. for 10-20 min; the above operation process is repeated several times until the total thickness of the metal layer reaches 100-500 nm.

9. The method for preparing a structure for exciting SPPs according to claim 3, characterized in that: In step S6, first, the substrate in step S4 is placed in an ultrasonic cleaning machine, the ultrasonic intensity is set to 10-20W, and immersed in an organic solvent for 5-10 minutes; then, the ultrasonic intensity is gradually increased every 1-3 minutes, and each intensity is increased by 5-8% over the previous intensity.

10. A method for exciting SPPs with structured transmission light field energy according to claim 1 or 2, characterized in that: The invention comprises a laser, a nano-microdisk array, and a spectrometer for receiving signals. The nano-microdisk array is arranged on the surface of a silicon dioxide substrate. The broadband laser emitted by the laser irradiates the nano-microdisk array to excite surface plasmons. The sharp metal triangular protrusions on the nano-microdisk strengthen the metal surface plasmons to achieve the convergence effect of the light field. At the same time, the plasmons excited by the metal disks of the nano-microdisk are transmitted between the metal disks through the evanescent field.

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