Ultrafast spectrum test loading system based on coupling of surface plasma and resonant cavity

Abstract

The invention relates to the technical field of nano photonics, and discloses an ultrafast spectrum test loading system based on surface plasma and resonant cavity coupling, comprising a substrate; the surface plasma mode generation structure is arranged on the substrate, the surface plasma mode generation structure is formed by a two-dimensional metal nanostructure, and the two-dimensional metal nanostructure is a metal film in the shape of a gold hole array or a gold grating array; the coupling layer is arranged above the surface plasma mode generating structure; the upper metal film is arranged on the coupling layer; the metal film and the upper-layer metal film form the micro-cavity structure; wherein the surface plasma mode generation structure and the microcavity structure are coupled to form the ultrafast spectrum test loading device. The ultrafast spectrum of the substance in the coupling layer between the surface plasma mode generation structure and the micro-cavity structure can be detected, so that the ultrafast characteristic of the substance can be researched, and the ultrafast spectrum test of the substance with extremely high transparency can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of nanophotonics, and in particular to an ultrafast spectrum test loading system based on surface plasma and resonant cavity coupling. Background Art

[0002] The ultrafast spectroscopy test system is an ultrafast time-resolved "pump-probe" spectroscopy technology that is used to characterize the kinetic processes of matter on a sub-picosecond to nanosecond time scale, thereby studying the photophysical and photochemical processes of matter.

[0003] In pump-probe experiments, a key to the excitation of matter is that the matter has a certain intensity of absorption ability for the excitation light. However, for some extremely transparent materials (such as graphene with a transparency of nearly 98%), it is difficult to measure their ultrafast spectra, which makes it inconvenient to study the ultrafast properties of such materials. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an ultrafast spectral test loading system based on surface plasmon coupling and resonant cavity coupling, which improves the interaction between light and matter therein through the coupling of surface plasmon and resonant cavity, and further studies the ultrafast characteristics of the matter therein.

[0005] The present invention provides an ultrafast spectral test loading system based on surface plasmon and resonant cavity coupling and a preparation method thereof, comprising: substrate; A surface plasmon mode generating structure is placed on the substrate, wherein the surface plasmon mode generating structure is formed by a two-dimensional metal nanostructure, and the two-dimensional metal nanostructure is a metal film in the shape of a gold hole array or a gold grating array; A coupling layer, disposed above the surface plasmon mode generating structure; An upper metal film is spin-coated on the coupling layer; A microcavity structure, wherein the metal film and the upper metal film form the microcavity structure, and the microcavity structure is a Fabry-Perot resonant cavity; Wherein, the coupling layer contains a sample to be tested, and the thickness of the coupling layer can be changed to adjust the coupling strength between the surface plasmon mode generating structure and the microcavity structure, and between the surface plasmon mode generating structure and the sample to be tested. The surface plasmon mode generating structure and the microcavity structure are coupled to form an ultrafast spectrum test loading device for detecting the ultrafast spectrum of the sample to be tested.

[0006] Optionally, a photoresist is spin-coated on the substrate, the gold hole array pattern and the gold grating array pattern are etched on the photoresist, and a metal film is deposited on the photoresist to form the gold hole array and the gold grating array.

[0007] Optionally, in the gold hole array, the hole period is 400 nm, the diameter is 165 nm, the depth is 200 nm, and the thickness of the metal film is 50 nm.

[0008] Optionally, in the gold grating array, the period of the grating is 400 nm, the duty cycle is 0.4, and the thickness of the metal film is 50 nm.

[0009] Optionally, the coupling layer is a polyvinyl alcohol aqueous solution, and the thickness of the coupling layer is adjusted by adjusting the concentration of the polyvinyl alcohol aqueous solution.

[0010] Optionally, the ultrafast spectrum of the sample to be tested is measured by a femtosecond pump-probe system to perform ultrafast time-resolved transient absorption spectroscopy measurement.

[0011] Optionally, the femtosecond pump-probe system comprises: A femtosecond laser, which serves as a light source; A beam splitter, used to split the femtosecond laser beam generated by the femtosecond laser into two beams, one for pumping and the other for detection; A frequency doubling crystal, used for doubling the frequency of the pump light beam through the frequency doubling crystal to obtain a pump pulse; A sample stage, used for placing the substrate; a spectrometer for receiving the probe beam and recording the intensity of the beam as a function of time; The data acquisition system is used to collect detector signals and perform data analysis.

[0012] Optional data analysis includes: Reflection spectroscopy analysis measures the transient absorption changes of the sample by analyzing the changes in the reflection spectrum with and without pump light.

[0013] The resonant cavity based on the gold hole array is obtained by the following steps: S01: Spin-coat a layer of positive photoresist on the substrate; S02: preparing the gold hole array pattern on the positive photoresist by focused ion beam etching; S03: Place the substrate into a vacuum evaporation coating machine to deposit a layer of gold film as a bottom mirror; S04: spin-coat a layer of polyvinyl alcohol aqueous solution on the gold film; S05: Deposit another layer of gold film on the polyvinyl alcohol layer as a top mirror.

[0014] The resonant cavity based on the gold grating array is obtained by the following steps: S11: spin coating a layer of positive photoresist on the substrate; S12: Fabrication of gold grating array patterns on positive photoresist by double-beam interferometry; S13: placing the substrate into a vacuum evaporation coating machine to deposit a layer of gold film as a bottom mirror; S14: spin coating a layer of polyvinyl alcohol aqueous solution on the gold film; S15: Deposit another layer of gold film on the polyvinyl alcohol layer as a top mirror.

[0015] The technical solution provided by the embodiment of the present invention has the following advantages compared with the prior art: An ultrafast spectrum test loading system based on surface plasmon coupling and resonant cavity coupling provided by an embodiment of the present invention is used to adjust the coupling strength between the surface plasmon mode generating structure and the microcavity structure, and between the samples to be tested by changing the thickness of the coupling layer. A strong coupling effect is formed between the surface plasmon mode generating structure and the microcavity structure, so that the surface plasmon mode generating structure and the microcavity structure are coupled to form an ultrafast spectrum test loading device, which is used to detect the ultrafast spectrum of the material in the coupling layer between the surface plasmon mode generating structure and the microcavity structure, and then the ultrafast characteristics of the material therein can be studied, and the ultrafast spectrum test of the material with extremely high transparency can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of a microcavity structure based on a gold hole array in an ultrafast spectroscopy test loading system based on coupling of surface plasmon and resonant cavity provided in an embodiment of the present invention.

[0017] Figure 2 A schematic diagram of a microcavity structure based on a gold grating array in an ultrafast spectroscopy test loading system based on coupling of surface plasmon and resonant cavity provided in an embodiment of the present invention. Figure 3 The figure is a schematic diagram of the preparation process of the resonant cavity of the gold hole array of the present invention. Figure 4 The figure is a schematic diagram of the preparation process of the resonant cavity of the gold grating array of the present invention.

[0018] Description of reference numerals: 1. Substrate; 2. Surface plasma mode generating structure; 3. Microcavity structure; 4. Coupling layer. DETAILED DESCRIPTION

[0019] A specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation.

[0020] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the technical solutions of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] The ultrafast spectroscopy test system is an ultrafast time-resolved "pump-probe" spectroscopy technology that is used to characterize the kinetic processes of matter on a sub-picosecond to nanosecond time scale, thereby studying the photophysical and photochemical processes of matter.

[0022] In pump-probe experiments, a key to the excitation of matter is that the matter has a certain intensity of absorption ability for the excitation light. However, for some extremely transparent materials (such as graphene with a transparency of nearly 98%), it is difficult to measure their ultrafast spectra, which makes it inconvenient to study the ultrafast properties of such materials.

[0023] To this end, an embodiment of the present invention provides an ultrafast spectral test loading system and a preparation method based on the coupling of surface plasmon and resonant cavity, which can enhance the interaction between light and matter therein through the coupling of surface plasmon and resonant cavity, and then study the ultrafast properties of the matter therein, thereby realizing ultrafast spectral testing of materials with extremely high transparency.

[0024] At least one embodiment of the present invention provides an ultrafast spectral test loading system based on surface plasmon coupling and resonant cavity coupling, comprising: substrate; A surface plasmon mode generating structure is placed on a substrate, wherein the surface plasmon mode generating structure is generated by a two-dimensional metal nanostructure, and the two-dimensional metal nanostructure is a metal film in the shape of a gold hole array or a gold grating array; A coupling layer, disposed above the surface plasmon mode generating structure; An upper metal film is disposed on the coupling layer; Microcavity structure: the metal film in the two-dimensional metal nanostructure forms a microcavity structure with the upper metal film, and the microcavity structure is a Fabry-Perot resonant cavity; Among them, the coupling layer contains the sample to be tested, and the thickness of the coupling layer can be changed to adjust the coupling strength between the surface plasmon mode generating structure and the microcavity structure, and between the surface plasmon mode generating structure and the sample to be tested. The surface plasmon mode generating structure and the microcavity structure are coupled to form an ultrafast spectrum test loading device, which is used to detect the ultrafast spectrum of the sample to be tested.

[0025] In the ultrafast spectral test loading system and preparation method based on surface plasmon coupling and resonant cavity coupling provided in the above-mentioned embodiment of the present invention, the interaction between light and matter therein is improved by coupling the surface plasmon and the resonant cavity, and the coupling strength is precisely controlled by controlling the thickness of the coupling layer, so that strong coupling is achieved between the plasma structure and the microcavity structure, thereby studying the ultrafast properties of the matter therein and realizing ultrafast spectral testing of materials with extremely high transparency.

[0026] The present invention is described below by several specific embodiments. In order to keep the following description of the embodiments of the present invention clear and concise, the detailed description of known functions and known components may be omitted. When any component of the embodiments of the present invention appears in more than one accompanying drawings, the component may be represented by the same reference numeral in each of the accompanying drawings.

[0027] like Figure 1 , Figure 2 As shown, the embodiment of the present invention provides an ultrafast spectral test loading system and a preparation method based on surface plasmon coupling and resonant cavity coupling, including: Base 1; A surface plasmon mode generating structure 2 is disposed on the substrate 1, and the surface plasmon mode generating structure 2 is formed by a two-dimensional metal nanostructure, and the two-dimensional metal nanostructure is a metal film in the shape of a gold hole array or a gold grating array; A coupling layer 4 is disposed above the surface plasmon mode generating structure 2; An upper metal film is provided on the coupling layer 4; A microcavity structure 3, wherein the metal film and the upper metal film form a microcavity structure 3, and the microcavity structure 3 is a Fabry-Perot resonant cavity; Among them, the coupling layer 4 includes a sample layer to be tested, and the sample to be tested is a material with high transparency. The thickness of the coupling layer 4 can be changed to adjust the coupling strength between the surface plasma mode generating structure 2 and the microcavity structure 3, and between the surface plasma mode generating structure 2 and the sample to be tested. The surface plasma mode generating structure 2 and the microcavity structure 3 are coupled to form an ultrafast spectrum test loading device, which is used to detect the ultrafast spectrum of the material between the surface plasma mode generating structure 2 and the microcavity structure 3.

[0028] Specifically, the substrate 1 may be a glass substrate 1, and the surface plasmon mode generating structure 2, the microcavity structure 3, the coupling layer 4, etc. may be prepared on the glass substrate 1. For example, the substrate 1 may be a square glass substrate 1 with a side length of 2 cm.

[0029] The surface plasmon mode generating structure 2 is placed on the substrate 1. The surface plasmon mode generating structure 2 is generated by a two-dimensional metal nanostructure. For example, the two-dimensional metal nanostructure is a metal film in the shape of a gold hole array or a gold grating array. The surface plasmon mode generating structure 2 has different morphologies and generates different mixed states.

[0030] The coupling layer 4 is disposed between the surface plasma mode generating structure 2 and the microcavity structure 3. In the present invention, the coupling layer 4 can be a polyvinyl alcohol-based aqueous solution, which is a high molecular polymer with high transparency. Depending on the different samples to be tested, the coupling layer 4 can also be other substances with high transparency.

[0031] A metal film is deposited on the coupling layer 4 as an upper metal film.

[0032] The metal film of the two-dimensional metal nanostructure and the upper metal film form a microcavity structure 3, and the microcavity structure 3 is a Fabry-Pérot cavity (Fabry-Perot resonant cavity).

[0033] The thickness of the polyvinyl alcohol group can be changed by changing the concentration of the polyvinyl alcohol group, so as to adjust the coupling strength between the surface plasmon mode generating structure 2 and the microcavity structure 3, and between the samples to be tested. A strong coupling effect is formed between the surface plasmon mode generating structure 2 and the microcavity structure 3, so that the surface plasmon mode generating structure 2 and the microcavity structure 3 are coupled to form an ultrafast spectrum test loading device, which is used to detect the ultrafast spectrum of the material between the surface plasmon mode generating structure 2 and the microcavity structure 3, and then the ultrafast characteristics of the material therein can be studied, and the ultrafast spectrum test of the material with extremely high transparency can be realized.

[0034] In an embodiment of the present invention, when preparing the surface plasma mode generating structure 2, photoresist can be first spin-coated on the substrate 1, the gold hole array pattern and the gold grating array pattern are etched on the photoresist, and a metal film is deposited on the photoresist to form the gold hole array and the gold grating array.

[0035] Different periods of two-dimensional metal nanostructures will result in different positions of their energy levels. Adjusting their periods can correspond to the energy levels of specific materials, thereby causing energy transfer.

[0036] For example, in order to observe the energy transfer using transient absorption spectroscopy, in the present invention, the period of the gold hole array holes is 400 mm, the diameter is 165 nm, the depth is 200 nm, and the thickness of the metal film is 50 nm. The period of the grating in the gold grating array is 400 nm, the duty cycle is 0.4, and the thickness of the metal film is 50 nm.

[0037] In the embodiment of the present invention, the ultrafast spectrum test loading device is used to detect the ultrafast spectrum of the material between the surface plasmon mode generating structure 2 and the microcavity structure 3, so as to study the ultrafast characteristics of the material therein and realize the ultrafast spectrum test of the material with extremely high transparency. The ultrafast spectrum test loading device can adopt a femtosecond pump detection system, and through the time-resolved split-second pump detection technology, the ultrafast time-resolved transient absorption spectrum measurement between the surface plasmon mode generating structure 2 and the microcavity structure 3 can be observed in real time.

[0038] Exemplarily, the ultrafast spectrum of the sample to be tested is measured by a femtosecond pump-probe system, including a femtosecond laser, a beam splitter, a frequency doubling crystal, a sample stage, a spectrometer, and a data acquisition system. Among them, the femtosecond laser is used as a light source; the beam splitter is used to split the femtosecond laser beam generated by the femtosecond laser into two beams, one for pumping and the other for detection; the frequency doubling crystal is used to double the pump beam through the frequency doubling crystal to obtain a pump pulse with a central wavelength of 400nm; the sample stage is used to place the ultrafast spectrum test loading system; the spectrometer is used to receive the detection beam and record the change of the beam intensity over time; the data acquisition system is used to collect the detector signal and perform data analysis.

[0039] Furthermore, the data analysis includes reflection spectrum analysis, which measures the transient absorption changes of the sample by analyzing the changes in the reflection spectrum with and without pump light.

[0040] In an exemplary embodiment of the present invention, a resonant cavity based on a gold hole array is obtained by the following steps: S01: Spin-coating a layer of positive photoresist on substrate 1; S02: preparing the gold hole array pattern on the positive photoresist by focused ion beam etching; S03: placing the substrate 1 into a vacuum evaporation coating machine to deposit a layer of gold film as a bottom mirror; S04: spin-coat a layer of polyvinyl alcohol aqueous solution on the gold film; S05: Deposit another layer of gold film on the polyvinyl alcohol layer as a top mirror.

[0041] By adopting the above preparation method, with the bottom mirror and the top mirror as the two surfaces of the Fabry-Pérot cavity, a coupled nanocavity based on the gold hole array and the microcavity can be obtained.

[0042] The resonant cavity based on the gold grating array is obtained by the following steps: S11: Spin-coating a layer of positive photoresist on the substrate 1; S12: Fabrication of gold grating array patterns on positive photoresist by double-beam interferometry; S13: placing the substrate 1 into a vacuum evaporation coating machine to deposit a layer of gold film as a bottom mirror; S14: spin coating a layer of polyvinyl alcohol aqueous solution on the gold film; S15: Deposit another layer of gold film on the polyvinyl alcohol layer as a top mirror.

[0043] By adopting the above preparation method, with the bottom mirror and the top mirror as the two surfaces of the Fabry-Pérot cavity, a coupled nanocavity based on the gold grating array and the microcavity can be obtained.

[0044] By adopting the above-mentioned preparation method, a coupled nanocavity of a surface plasma mode generating structure 2 and a microcavity can be obtained, and by controlling the thickness of the coupling layer 4, the coupling strength of the surface plasma mode generating structure 2 and the microcavity structure 3 can be adjusted, so that the surface plasma mode generating structure 2 and the microcavity can achieve a strong coupling effect, so that the surface plasma mode generating structure 2 and the microcavity are coupled to form an ultrafast spectrum test loading device for detecting the ultrafast spectrum of the substance between the surface plasma mode generating structure 2 and the microcavity structure 3, and then the ultrafast characteristics of the substance therein can be studied, and the ultrafast spectrum test of the substance with extremely high transparency can be realized.

[0045] The above inventions are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An ultrafast spectral test loading system based on surface plasmon and resonant cavity coupling, characterized in that: include: Base (1); A surface plasmon mode generating structure (2) is placed on the substrate (1), wherein the surface plasmon mode generating structure (2) is formed by a two-dimensional metal nanostructure, wherein the two-dimensional metal nanostructure is a metal film in the form of a gold hole array or a gold grating array; A coupling layer (4) is disposed above the surface plasmon mode generating structure (2); An upper metal film is spin-coated on the coupling layer (4); A microcavity structure (3), wherein the metal film and the upper metal film form the microcavity structure (3), and the microcavity structure (3) is a Fabry-Perot resonant cavity; The coupling layer (4) contains a sample to be tested, and the thickness of the coupling layer (4) can be changed to adjust the coupling strength between the surface plasmon mode generating structure (2) and the microcavity structure (3), and between the surface plasmon mode generating structure (2) and the sample to be tested. The surface plasmon mode generating structure (2) and the microcavity structure (3) are coupled to form an ultrafast spectrum test loading device for detecting the ultrafast spectrum of the sample to be tested.

2. The ultrafast spectroscopy test loading system based on surface plasmon and resonant cavity coupling according to claim 1, characterized in that: The substrate (1) is spin-coated with photoresist, the gold hole array pattern and the gold grating array pattern are etched on the photoresist, and a metal film is deposited on the photoresist to form the gold hole array and the gold grating array.

3. The ultrafast spectral test loading system based on surface plasmon and resonant cavity coupling according to claim 2, characterized in that: In the gold hole array, the hole period is 400nm, the diameter is 165nm, the depth is 200nm, and the thickness of the metal film is 50nm.

4. The ultrafast spectroscopy test loading system based on surface plasmon and resonant cavity coupling according to claim 2, characterized in that: In the gold grating array, the period of the grating is 400 nm, the duty cycle is 0.4, and the thickness of the metal film is 50 nm.

5. The ultrafast spectroscopy test loading system based on surface plasmon and resonant cavity coupling according to claim 1, characterized in that: The coupling layer (4) is a polyvinyl alcohol aqueous solution, and the thickness of the coupling layer (4) is adjusted by adjusting the concentration of the polyvinyl alcohol aqueous solution.

6. The ultrafast spectroscopy test loading system based on surface plasmon and resonant cavity coupling according to claim 1, characterized in that: The ultrafast spectrum of the sample to be tested is measured by a femtosecond pump-probe system to perform ultrafast time-resolved transient absorption spectroscopy measurements.

7. The ultrafast spectroscopy test loading system based on surface plasmon and resonant cavity coupling according to claim 6, characterized in that: The femtosecond pump-probe system comprises: A femtosecond laser, which serves as a light source; A beam splitter, used to split the femtosecond laser beam generated by the femtosecond laser into two beams, one beam for pumping and the other beam for detection, the beam for detection being injected into the microcavity structure (3); A frequency doubling crystal, used for doubling the frequency of the pump light beam through the frequency doubling crystal to obtain a pump pulse; A sample stage, used for placing the substrate (1); A spectrometer, used for receiving the detection light beam reflected by the microcavity structure (3), and recording the change of the light beam intensity over time; The data acquisition system is used to collect detector signals and perform data analysis.

8. The ultrafast spectroscopy test loading system based on surface plasmon and resonant cavity coupling according to claim 7, characterized in that: Data analysis includes: Reflection spectroscopy analysis measures the transient absorption changes of the sample by analyzing the changes in the reflection spectrum with and without pump light.

9. The ultrafast spectroscopy test loading system based on surface plasmon and resonant cavity coupling according to claim 1, characterized in that: The resonant cavity based on the gold hole array is obtained by the following steps: S01: spin coating a layer of positive photoresist on the substrate (1); S02: preparing the gold hole array pattern on the positive photoresist by focused ion beam etching; S03: placing the substrate (1) into a vacuum evaporation coating machine to deposit a layer of gold film as a bottom mirror; S04: spin-coat a layer of polyvinyl alcohol aqueous solution on the gold film; S05: Deposit another layer of gold film on the polyvinyl alcohol layer as a top mirror.

10. The ultrafast spectral test loading system based on surface plasmon and resonant cavity coupling according to claim 1, characterized in that: The resonant cavity based on the gold grating array is obtained by the following steps: S11: spin coating a layer of positive photoresist on the substrate (1); S12: Fabrication of gold grating array patterns on positive photoresist by double-beam interferometry; S13: placing the substrate (1) into a vacuum evaporation coating machine to deposit a layer of gold film as a bottom mirror; S14: spin coating a layer of polyvinyl alcohol aqueous solution on the gold film; S15: Deposit another layer of gold film on the polyvinyl alcohol layer as a top mirror.

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