Ultrafast optical spectrum testing loading system based on surface plasmon and resonant cavity coupling

Abstract

The application relates to the technical field of nanophotonics, and discloses an ultrafast spectrum test loading system based on surface plasmon and resonant cavity coupling, which comprises a substrate, a surface plasmon mode generation structure arranged on the substrate, a two-dimensional metal nanostructure formed by the surface plasmon mode generation structure, a metal film in the shape of a gold hole array or a gold grating array, a coupling layer arranged above the surface plasmon mode generation structure, an upper metal film arranged on the coupling layer, a microcavity structure formed by the metal film and the upper metal film, and an ultrafast spectrum test loading device formed by coupling the surface plasmon mode generation structure and the microcavity structure. The ultrafast spectrum of the substance in the coupling layer between the surface plasmon mode generation structure and the microcavity structure can be detected, the ultrafast characteristics 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 present application relates to the technical field of nanophotonics, and particularly relates to an ultrafast spectrum test loading system based on surface plasmon and resonant cavity coupling. BACKGROUND

[0002] The ultrafast spectrum test system is an ultrafast time-resolved 'pump-probe' spectrum technology, which is used for characterizing the dynamic process of a substance in a time scale of sub-picosecond to nanosecond, so as to study the photophysical and photochemical processes of the substance.

[0003] In the pump-probe experiment, a key to excite the substance lies in that the substance has a certain absorption capacity for the excitation light, however, for some substances with extremely high transparency (such as graphene with a transparency close to 98%), it is difficult to measure the ultrafast spectrum of the substance, and it is inconvenient to study the ultrafast characteristics of the substance. SUMMARY

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

[0005] The present application provides an ultrafast spectrum test loading system based on surface plasmon and resonant cavity coupling and a preparation method, which comprises:

[0006] a substrate;

[0007] a surface plasmon mode generating structure disposed on the substrate, the surface plasmon mode generating structure formed by a two-dimensional metal nanostructure, the two-dimensional metal nanostructure being a gold hole array or a gold grating array-shaped metal film;

[0008] a coupling layer arranged above the surface plasmon mode generating structure;

[0009] an upper metal film spin-coated on the coupling layer;

[0010] a microcavity structure, the metal film and the upper metal film forming the microcavity structure, the microcavity structure being a Fabry-Perot resonant cavity;

[0011] The coupling layer contains a sample to be measured, 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 measured. 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 measured.

[0012] 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.

[0013] Optionally, in the gold hole array, the period of the hole is 400 nm, the diameter of the hole is 165 nm, the depth of the hole is 200 nm, and the thickness of the metal film is 50 nm.

[0014] Optionally, in the gold grating array, the period of the grating is 400 nm, the duty cycle of the grating is 0.4, and the thickness of the metal film is 50 nm.

[0015] 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.

[0016] Optionally, the ultrafast spectrum of the sample to be measured is measured by a femtosecond pump-probe system to perform ultrafast time-resolved transient absorption spectrum measurement.

[0017] Optionally, the femtosecond pump-probe system comprises:

[0018] a femtosecond laser as a light source;

[0019] a beam splitter for splitting the femtosecond laser beam generated by the femtosecond laser into two beams, one for pumping and the other for probing;

[0020] a frequency doubling crystal for frequency doubling the pumping beam through the frequency doubling crystal to obtain a pumping pulse;

[0021] a sample stage for placing the substrate;

[0022] a spectrometer for receiving the probe beam and recording the change of the beam intensity with time;

[0023] a data acquisition system for acquiring the detector signal and performing data analysis.

[0024] Optionally, the data analysis comprises:

[0025] reflection spectrum analysis, which measures the transient absorption change of the sample by analyzing the change of the reflection spectrum with or without pumping light.

[0026] The resonant cavity based on the gold hole array is obtained by the following steps:

[0027] S01: spin-coating a layer of positive photoresist on the substrate;

[0028] S02: preparing the gold hole array pattern on the positive photoresist by focused ion beam etching;

[0029] S03: Put the substrate into a vacuum evaporation coater, deposit a layer of gold film as the bottom mirror;

[0030] S04: Spin a layer of polyvinyl alcohol aqueous solution on the gold film;

[0031] S05: Deposit a layer of gold film on the polyvinyl alcohol layer as the top mirror.

[0032] The resonant cavity based on the gold grating array is obtained by the following steps:

[0033] S11: Spin a layer of positive photoresist on the substrate;

[0034] S12: Prepare a gold grating array pattern on the positive photoresist by double-beam interference;

[0035] S13: Put the substrate into a vacuum evaporation coater, deposit a layer of gold film as the bottom mirror;

[0036] S14: Spin a layer of polyvinyl alcohol aqueous solution on the gold film;

[0037] S15: Deposit a layer of gold film on the polyvinyl alcohol layer as the top mirror.

[0038] The technical scheme provided by the embodiment of the present application has the following advantages compared with the prior art:

[0039] The ultrafast spectrum test loading system based on the coupling of surface plasmons and resonant cavities provided by the embodiment of the present application can realize the adjustment of the coupling strength between the surface plasmon generating structure and the microcavity structure, and between the samples to be measured, by changing the thickness of the coupling layer. The strong coupling effect is formed between the surface plasmon generating structure and the microcavity structure, so that the surface plasmon 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 substance in the coupling layer between the surface plasmon generating structure and the microcavity structure, and further to study the ultrafast characteristics of the substance, and realize the ultrafast spectrum test of the substance with extremely high transparency. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The microcavity structure based on the gold hole array in the ultrafast spectrum test loading system based on the coupling of surface plasmons and resonant cavities provided by the embodiment of the present application is shown in the schematic diagram.

[0041] Figure 2 The microcavity structure based on the gold grating array in the ultrafast spectrum test loading system based on the coupling of surface plasmons and resonant cavities provided by the embodiment of the present application is shown in the schematic diagram.

[0042] Figure 3 The preparation process of the resonant cavity of the gold hole array of the present application is shown in the schematic diagram.

[0043] Figure 4 The preparation flowchart of the resonant cavity of the gold grating array of the present application.

[0044] Explanation of reference signs:

[0045] 1, substrate; 2, surface plasmon mode generating structure; 3, microcavity structure; 4, coupling layer. DETAILED DESCRIPTION

[0046] One specific embodiment of the present application will be described in detail below with reference to the accompanying drawings, but it should be understood that the scope of protection of the present application is not limited by the specific embodiment.

[0047] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the technical solutions of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0048] The ultrafast optical spectrum test system is an ultrafast time-resolved "pump-probe" optical spectrum technology, which is used for characterizing the dynamic process of a substance in a time scale of sub-picosecond to nanosecond, so as to study the photophysical and photochemical processes of the substance.

[0049] In the pump-probe experiment, a key to the excitation of the substance is that the substance has a certain absorption capacity for the excitation light, however, for some substances with extremely high transparency (such as graphene with a transparency close to 98%), it is difficult to measure the ultrafast spectrum thereof, and it is inconvenient to study the ultrafast characteristics of such substances.

[0050] Therefore, the embodiment of the present application provides an ultrafast spectrum test loading system based on the coupling of surface plasmons and resonant cavities and a preparation method, which can improve the interaction between light and matter by the coupling of surface plasmons and resonant cavities, and then study the ultrafast characteristics of the matter, so as to realize the ultrafast spectrum test of the substance with extremely high transparency.

[0051] At least one embodiment of the present application provides an ultrafast spectrum test loading system based on the coupling of surface plasmons and resonant cavities, which comprises:

[0052] a substrate;

[0053] a surface plasmon mode generating structure is disposed on the substrate, 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 form of a gold hole array or a gold grating array;

[0054] a coupling layer is disposed above the surface plasmon mode generating structure;

[0055] an upper metal film is disposed on the coupling layer;

[0056] a microcavity structure is formed by the metal film in the two-dimensional metal nanostructure and the upper metal film, and the microcavity structure is a Fabry-Perot resonant cavity;

[0057] The coupling layer contains a sample to be measured, 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 measured, the surface plasmon mode generating structure and the microcavity structure are coupled to form an ultrafast optical spectrum test loading device for detecting the ultrafast optical spectrum of the sample to be measured.

[0058] In the ultrafast optical spectrum test loading system and preparation method based on the coupling between surface plasmons and resonant cavities provided by the above embodiments of the application, the light-matter interaction is improved through the coupling between surface plasmons and resonant cavities, the coupling strength is accurately controlled by controlling the thickness of the coupling layer, the strong coupling between the plasmonic structure and the microcavity structure is achieved, and the ultrafast characteristics of the matter are further studied, thereby realizing the ultrafast optical spectrum test of a highly transparent matter.

[0059] The application will be described in detail below with reference to several specific embodiments. In order to keep the following description of the embodiments of the application clear and concise, the detailed description of known functions and known components can be omitted. When any component of the embodiments of the application appears in more than one figure, the component can be denoted by the same reference numeral in each figure.

[0060] As shown in Figure 1 , Figure 2 The application provides an ultrafast optical spectrum test loading system and preparation method based on the coupling between surface plasmons and resonant cavities, which comprises the following steps:

[0061] a substrate 1;

[0062] a surface plasmon mode generating structure 2 is disposed on the substrate 1, 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 form of a gold hole array or a gold grating array;

[0063] a coupling layer 4 is disposed above the surface plasmon mode generating structure 2;

[0064] an upper metal film is disposed on the coupling layer 4;

[0065] The microcavity structure 3 is formed by the metal film and the upper metal film, and the microcavity structure 3 is a Fabry-Pérot resonant cavity.

[0066] The coupling layer 4 contains a sample layer to be measured, the sample to be measured is a substance with high transparency, 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 measured. The surface plasmon mode generating structure 2 and the microcavity structure 3 are coupled to form an ultrafast spectrum test device, which is used to detect the ultrafast spectrum of the substance between the surface plasmon mode generating structure 2 and the microcavity structure 3.

[0067] Specifically, the substrate 1 can be a glass substrate 1, and the surface plasmon mode generating structure 2, the microcavity structure 3, the coupling layer 4, etc. can be prepared on the glass substrate 1. For example, the substrate 1 can be a square glass substrate 1 with a side length of 2 cm.

[0068] The surface plasmon mode generating structure 2 is placed on the substrate 1, and the surface plasmon mode generating structure 2 is generated by a two-dimensional metal nanostructure, for example, a metal film in the form of a gold hole array or a gold grating array. The surface plasmon mode generating structure 2 has different topographies and generates different mixed states.

[0069] The coupling layer 4 is arranged between the surface plasmon mode generating structure 2 and the microcavity structure 3. In the present application, the coupling layer 4 can be a polyvinyl alcohol-based aqueous solution, and polyvinyl alcohol is a high-molecular polymer with high transparency. According to different samples to be measured, the coupling layer 4 can also be other substances with high transparency.

[0070] A layer of metal film is deposited on the coupling layer 4 as an upper metal film.

[0071] The metal film of the two-dimensional metal nanostructure and the upper metal film constitute the microcavity structure 3, and the microcavity structure 3 is a Fabry-Pérot cavity.

[0072] The thickness of the polyvinyl alcohol can be changed by changing the concentration of the polyvinyl alcohol, which is used to adjust the coupling strength between the surface plasmon mode generating structure 2 and the microcavity structure 3 and between the sample to be measured. The surface plasmon mode generating structure 2 and the microcavity structure 3 form a strong coupling effect, so that the surface plasmon mode generating structure 2 and the microcavity structure 3 are coupled to form an ultrafast spectrum test device, which is used to detect the ultrafast spectrum of the substance between the surface plasmon mode generating structure 2 and the microcavity structure 3. Further, the ultrafast characteristics of the substance can be studied, and the ultrafast spectrum test of the substance with extremely high transparency can be realized.

[0073] In the embodiment of the present application, when the surface plasmon mode generating structure 2 is prepared, a photoresist can be first spin-coated on the substrate 1, a gold hole array pattern and a 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.

[0074] Different periods of the two-dimensional metal nanostructure result in different energy level positions, and the period can be adjusted to correspond to the energy level of a specific material, thereby causing energy transfer.

[0075] For example, in order to observe the energy transfer using transient absorption spectroscopy, in the present application, the period of the gold hole array is 400 mm, the diameter is 165 nm, the depth is 200 nm, and the thickness of the metal film is 50 nm. 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.

[0076] In the embodiment of the present application, the ultrafast spectroscopy test loading device is used to detect the ultrafast spectroscopy of the substance between the surface plasmon mode generating structure 2 and the microcavity structure 3, so as to study the ultrafast characteristics of the substance and realize the ultrafast spectroscopy test of the substance with extremely high transparency. The ultrafast spectroscopy test loading device can adopt a femtosecond pump-probe system, and through the time-resolved femtosecond pump-probe technology, the ultrafast time-resolved transient absorption spectroscopy measurement between the surface plasmon mode generating structure 2 and the microcavity structure 3 can be observed in real time.

[0077] For example, the ultrafast spectroscopy of the sample to be measured is measured by a femtosecond pump-probe system, which includes a femtosecond laser, a beam splitter, a frequency doubling crystal, a sample stage, a spectrometer, and a data acquisition system. The femtosecond laser is used as a light source. The beam splitter is used to divide the femtosecond laser beam generated by the femtosecond laser into two beams, one of which is used for pumping and the other of which is used for detection. The frequency doubling crystal is used to double the frequency of the pump beam through the frequency doubling crystal to obtain a pump pulse with a center wavelength of 400 nm. The sample stage is used to place the ultrafast spectroscopy test loading system. The spectrometer is used to receive the probe beam and record the change of the beam intensity with time. The data acquisition system is used to acquire the detector signal and perform data analysis.

[0078] Further, the data analysis includes reflection spectrum analysis, which measures the transient absorption change of the sample by analyzing the change of the reflection spectrum with or without pump light.

[0079] In an exemplary embodiment of the present application, the resonant cavity based on the gold hole array is obtained by the following steps:

[0080] S01: spin-coating a layer of positive photoresist on the substrate 1;

[0081] S02: preparing the gold hole array pattern on the positive photoresist by focused ion beam etching;

[0082] S03: Put the substrate 1 into a vacuum evaporation coater, and deposit a layer of gold film as the bottom mirror;

[0083] S04: Spin a layer of polyvinyl alcohol aqueous solution on the gold film;

[0084] S05: Deposit a layer of gold film as the top mirror on the polyvinyl alcohol layer.

[0085] By using the above preparation method, the coupling nanocavity based on the gold grating array and the microcavity can be obtained by taking the bottom mirror and the top mirror as the two surfaces of the Fabry-Pérot cavity.

[0086] The resonant cavity based on the gold grating array is obtained by the following steps:

[0087] S11: Spin a layer of positive photoresist on the substrate 1;

[0088] S12: Prepare a gold grating array pattern on the positive photoresist by double-beam interference;

[0089] S13: Put the substrate 1 into a vacuum evaporation coater, and deposit a layer of gold film as the bottom mirror;

[0090] S14: Spin a layer of polyvinyl alcohol aqueous solution on the gold film;

[0091] S15: Deposit a layer of gold film as the top mirror on the polyvinyl alcohol layer.

[0092] By using the above preparation method, the coupling nanocavity based on the gold grating array and the microcavity can be obtained by taking the bottom mirror and the top mirror as the two surfaces of the Fabry-Pérot cavity.

[0093] By using the above preparation method, the coupling nanocavity of the surface plasmon mode generating structure 2 and the microcavity can be obtained, and by controlling the thickness of the coupling layer 4, the coupling strength between the surface plasmon mode generating structure 2 and the microcavity structure 3 can be adjusted, so that the strong coupling effect between the surface plasmon mode generating structure 2 and the microcavity can be achieved, and thus the superfast spectrum test loading device formed by the coupling between the surface plasmon mode generating structure 2 and the microcavity structure 3 can be used to detect the superfast spectrum of the substance between the surface plasmon mode generating structure 2 and the microcavity structure 3, and further the superfast characteristics of the substance can be studied, and the superfast spectrum test of the substance with extremely high transparency can be realized.

[0094] The above invention is only a few specific embodiments of the present invention, but the embodiments of the present invention are not limited thereto, and any changes that can be thought of by those skilled in the art shall fall within the protection scope of the present invention.

Claims

1. An ultrafast optical spectrum testing loading system based on surface plasmon and resonant cavity coupling, characterized in that, It comprises: a substrate (1); a surface plasmon mode generating structure (2) disposed on the substrate (1), the surface plasmon mode generating structure (2) is formed by two-dimensional metal nanostructure, which is gold hole array or gold grating array shaped metal film; a coupling layer (4) disposed above the surface plasmon mode generating structure (2); an upper layer of metal film spin-coated on the coupling layer (4); a microcavity structure (3), the metal film and the upper layer of metal film form the microcavity structure (3), which is a Fabry-Perot resonant cavity; wherein the coupling layer (4) contains a sample to be tested, 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 optical spectrum test loading device for detecting the ultrafast optical spectrum of the sample to be tested; a photoresist is 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; in the gold hole array, the period of the hole is 400 nm, the diameter is 165 nm, the depth is 200 nm, and the thickness of the metal film is 50 nm; 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.

2. The ultrafast optical spectrum test loading system based on surface plasmon and resonant cavity coupling according to claim 1, wherein, The coupling layer (4) is polyvinyl alcohol aqueous solution, and the thickness of the coupling layer (4) is adjusted by adjusting the concentration of polyvinyl alcohol aqueous solution.

3. The ultrafast optical spectrum test loading system based on surface plasmon and resonant cavity coupling according to claim 1, wherein, The ultrafast optical spectrum of the sample to be tested is measured by a femtosecond pump-probe system to measure the ultrafast time-resolved transient absorption spectrum.

4. The ultrafast optical spectrum test loading system based on surface plasmon and resonant cavity coupling according to claim 3, characterized in that, The femtosecond pump-probe system comprises: a femtosecond laser as a light source; a beam splitter for splitting the femtosecond laser beam generated by the femtosecond laser into two beams, one for pumping and the other for detection, the beam for detection is injected into the microcavity structure (3); a frequency doubling crystal for doubling the frequency of the pump beam through the frequency doubling crystal to obtain a pump pulse; a sample stage for placing the substrate (1); a spectrometer for receiving the reflected probe beam of the microcavity structure (3) and recording the change of the beam intensity with time; a data acquisition system for acquiring the detector signal and performing data analysis.

5. The ultrafast optical spectrum test loading system based on surface plasmon and resonant cavity coupling according to claim 4, characterized in that, Data analysis includes: reflection spectrum analysis, by analyzing the change of reflection spectrum with or without pump light, to measure the transient absorption change of the sample.

6. The ultrafast optical spectrum test loading system based on surface plasmon and resonant cavity coupling according to claim 1, wherein, The resonant cavity based on gold hole array is obtained by the following steps: S01: spin-coat a layer of positive photoresist on the substrate (1); S02: prepare the gold hole array pattern on the positive photoresist by focused ion beam etching; S03: place 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: A layer of gold film is deposited again on the polyvinyl alcohol layer as the top mirror.

7. The ultrafast optical spectrum test loading system based on surface plasmon and resonant cavity coupling according to claim 1, wherein, The resonant cavity based on the gold grating array is obtained by the following steps: S11: A layer of positive photoresist is spin-coated on the substrate (1); S12: A gold grating array pattern is prepared on the positive photoresist by double-beam interference; S13: The substrate (1) is placed in a vacuum evaporation film plating machine, and a layer of gold film is deposited as the bottom mirror; S14: A layer of polyvinyl alcohol aqueous solution is spin-coated on the gold film; S15: A layer of gold film is deposited again on the polyvinyl alcohol layer as the top mirror.

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