Quasiparticle resonance enhanced brillouin spectroscopy system

Abstract

Embodiments of the present disclosure provide a quasi-particle resonance enhanced Brillouin spectrum system, comprising: a resonance medium containing tunable quasi-particle light emission; a layered material sample attached to the resonance medium, modulating the quasi-particle light emission in the resonance medium based on interlayer vibration; a laser light source for generating laser light, the laser light being focused on the resonance medium to undergo Brillouin scattering with the quasi-particle modulated by the interlayer vibration, generating Brillouin scattered light; wherein the frequency of the quasi-particle of the resonance medium is tuned to resonate with the frequency of the laser light, and the quasi-particle light emission is enhanced by resonance to enhance the Brillouin signal of the interlayer vibration of the layered material sample carried by the quasi-particle; a Fabry-Perot interferometer for analyzing the Brillouin scattered light and outputting Brillouin scattered light with a preset frequency.

Description

Technical Field

[0001] The present disclosure relates to the technical field of Brillouin spectroscopy testing, and in particular to a quasiparticle resonance enhanced Brillouin spectroscopy system. Background Art

[0002] Mechanical interactions at nanoscale interfaces carry crucial information about atomic-scale interface structure, thermal conductivity, and optoelectronic properties. However, due to the very limited electron-phonon coupling, these interactions cannot be directly measured using classical vibrational spectroscopy. For example, ultra-low-frequency shear or breathing phonons in layered van der Waals materials, characterized by the collective co-directional motion of atomic layers, contain unique information about the global crystal structure and hidden interfaces. However, these phonon vibrational modes, characterized by the collective co-directional motion of atomic layers, cannot produce detectable electric dipole radiation due to the mutual cancellation of changes in polarizability between adjacent layers. Furthermore, interlayer vibrational modes in thicker layered materials are densely distributed, and the low-frequency modes are very low. For example, in a 100-layer layered material, the low-frequency modes are approximately 1 / 100th the bulk mode frequency, and the resolution required to distinguish between these modes is 100 times that of a two-layer sample. Therefore, a new high-resolution vibrational spectroscopy technique is needed to detect low-frequency interlayer vibrational modes. Summary of the Invention

[0003] In view of this, the present disclosure provides a quasiparticle resonance enhanced Brillouin spectroscopy system for at least partially solving the above technical problems.

[0004] Embodiments of the present disclosure provide a quasiparticle resonance-enhanced Brillouin spectroscopy system, comprising: a resonant medium containing tunable luminescent quasiparticles; a layered material sample, bonded to the resonant medium, which modulates the quasiparticles in the resonant medium to emit light based on interlayer vibrations; a laser light source, which generates laser light, and the laser light is focused on the resonant medium to cause Brillouin scattering with the quasiparticles modulated by the interlayer vibrations, thereby generating Brillouin scattered light; wherein the frequency of the quasiparticles in the resonant medium is tuned to resonate with the frequency of the laser light, and the quasiparticle emission is enhanced by resonance to enhance the Brillouin signal of the interlayer vibrations of the layered material sample carried by the quasiparticles; and a Fabry-Perot interferometer, which analyzes the Brillouin scattered light and outputs Brillouin scattered light with a preset frequency.

[0005] According to an embodiment of the present disclosure, the system further includes: a polarization beam splitter for reflecting the vertically polarized component in the laser light generated by the laser light source; and a microscope objective lens for focusing the vertically polarized laser light on the resonant medium.

[0006] According to an embodiment of the present disclosure, the system also includes: a polarization resolution component, including a polarizer and a quarter-wave plate, which is used to interact with the polarization beam splitter of the incident light path, and realize Brillouin spectrum detection under parallel polarization or cross-polarization configuration by inserting or removing the polarizer and quarter-wave plate.

[0007] According to an embodiment of the present disclosure, the system also includes: an objective lens holder for mounting a microscope objective lens; a translation stage for mounting the objective lens holder, and by adjusting the translation stage, the laser is focused onto the resonant medium on the layered material samples with different numbers of layers to measure the interlayer vibration of the layered material samples with different numbers of layers.

[0008] According to an embodiment of the present disclosure, the system further includes: a rotating sample stage, the rotating sample stage including a sample holder and a rotating stage, the layered material sample is fixed on the sample holder, and the sample holder is movable relative to the rotating stage; wherein, the light scattering signal of the resonant medium corresponding to different incident angles is detected by rotating the rotating stage; and the light spot of the resonant medium is located on the central axis of the rotating stage by adjusting the position of the sample holder on the rotating stage.

[0009] According to an embodiment of the present disclosure, the quasiparticles include plasmons or excitons.

[0010] According to the embodiments of the present disclosure, when the quasiparticles are plasmons, the resonant medium is metal particles, and the plasmon energy is tuned by adjusting the particle size; when the quasiparticles are excitons, the resonant medium is transition metal carbon disulfide or a twisted layered semiconductor, and the exciton energy can be tuned by changing the temperature or twist angle.

[0011] According to an embodiment of the present disclosure, the layered material sample is distributed with graphite having different numbers of layers, the resonance medium includes tungsten disulfide, and the tungsten disulfide and the graphite form a heterojunction.

[0012] According to an embodiment of the present disclosure, the layered material sample includes different inter-layer vibration modes divided based on the number of layers covered by one node, and different inter-layer vibration modes have different frequencies and amplitudes.

[0013] According to an embodiment of the present disclosure, the interlayer vibration mode includes a shear mode or a breathing mode.

[0014] According to the quasiparticle resonance-enhanced Brillouin spectroscopy system provided by the embodiments of the present disclosure, laser light generated by a laser light source is focused onto the surface of a resonant medium, where it scatters light with quasiparticles. The photoluminescence of the quasiparticles, modulated by the interlayer vibrations of the underlying layered material, is resonantly enhanced, resulting in an enhanced signal of the interlayer vibrations. After analysis by a Fabry-Perot interferometer, this signal is detected as a series of peaks in the quasiparticle photoluminescence intensity-frequency relationship. The different frequencies, amplitudes, and linewidths of different interlayer modes result in different modulations of the quasiparticles, resulting in peaks with different frequencies, amplitudes, and linewidths after interferometer analysis. Furthermore, with the help of a rotating stage, interlayer phonon signals corresponding to the different wave vectors contained in the quasiparticles can be collected. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0016] Figure 1 Schematically shows a structural diagram of a quasiparticle resonance enhanced Brillouin spectroscopy system according to an embodiment of the present disclosure;

[0017] Figure 2 The structure of a quasiparticle resonance enhanced Brillouin spectroscopy system according to another embodiment of the present disclosure is schematically shown.

[0018] Description of reference numerals:

[0019] 11-rotating sample stage, 111-sample holder, 112-rotating stage, 12-layered material sample, 13-resonant medium, 20-microscope objective lens, 21-objective lens holder, 30-translation stage, 40-polarizer, 50-quarter wave plate, 60-polarization beam splitter, 70-laser light source, 80-Fabry-Perot interferometer. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0021] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0022] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0023] When expressions such as "at least one of A, B, and C, etc." are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0024] For the conventional Brillouin spectrum system, the application provides a quasi-particle resonance enhanced Brillouin spectrum system, which adopts the Brillouin spectrum technology and combines the technology of attaching a resonance medium on a layered material sample to achieve resonance enhancement of interlayer phonons. The application can provide a quasi-particle resonance enhanced Brillouin spectrum system which is easy to build and low in cost, can detect shear mode and breathing mode phonons of a layered material, and can study mechanical interaction of a nanoscale interface. The application is described below in combination with specific embodiments.

[0025] Figure 1 A structural diagram of a quasi-particle resonance enhanced Brillouin spectrum system according to an embodiment of the application is schematically shown.

[0026] As shown in Figure 1 , the quasi-particle resonance enhanced Brillouin spectrum system can include a resonance medium 13, a layered material sample 12, a laser light source 70, and a Fabry-Perot interferometer 80.

[0027] The resonance medium 13 contains tunable luminescent quasi-particles.

[0028] The layered material sample 12 is attached to the resonance medium 13 and modulates the luminescence of the quasi-particles in the resonance medium based on interlayer vibration.

[0029] The laser light source 70 is configured to generate laser light, and the laser light is focused on the resonance medium 13 to cause Brillouin scattering with the quasi-particles modulated by interlayer vibration, thereby generating Brillouin scattering light; wherein the frequency of the quasi-particles in the resonance medium 13 is tuned to resonate with the frequency of the laser light, and the luminescence of the quasi-particles is enhanced by resonance, so as to enhance the Brillouin signal of the interlayer vibration of the layered material sample 12 carried by the quasi-particles.

[0030] The Fabry-Perot interferometer 80 is configured to analyze the Brillouin scattering light and output Brillouin scattering light with a preset frequency. After the light scattering signal of the quasi-particles is analyzed by the Fabry-Perot interferometer 80, the interlayer vibration mode carried by the quasi-particles appears in the form of peaks on an intensity-frequency spectrum.

[0031] According to the quasi-particle resonance enhanced Brillouin spectrum system of the embodiment of the application, the laser light generated by the laser light source is focused on the surface of the resonance medium and causes light scattering with the quasi-particles. The photoluminescence of the quasi-particles modulated by the interlayer vibration of the underlying layered material is enhanced by resonance, so that the signal of the interlayer vibration is enhanced. After being analyzed by the Fabry-Perot interferometer, the signal is detected in the form of a series of peaks in the intensity-frequency relationship of the photoluminescence of the quasi-particles.

[0032] Figure 2 A structural diagram of a quasi-particle resonance enhanced Brillouin spectrum system according to another embodiment of the application is schematically shown.

[0033] like Figure 2 As shown, based on the above embodiment, the quasiparticle resonance enhanced Brillouin spectroscopy system may further include a polarization beam splitter 60 and a microscope objective lens 20 .

[0034] The polarization beam splitter 60 is used to reflect the vertical polarization component of the laser light generated by the laser light source 70 .

[0035] The microscope objective lens 20 is used to focus the vertically polarized laser light onto the resonance medium 13 .

[0036] Specifically, the vertical polarization component in the laser generated by the laser light source 70 is reflected by the polarization beam splitter 60 and then focused on the resonance medium 13 by the objective lens 20, forming a laser spot, resonantly exciting the quasiparticles in the resonance medium 13, thereby enhancing the modulation signal of the quasiparticles modulated by the interlayer vibration of the layered material sample 12.

[0037] Continue reading Figure 2 Based on the above embodiment, the quasiparticle resonance enhanced Brillouin spectroscopy system further includes: a polarization resolution component.

[0038] The polarization resolution component includes a polarizer 40 and a quarter-wave plate 50, which is used to work in conjunction with a polarization beam splitter 60 in the incident light path. By inserting or removing the polarizer 40 and the quarter-wave plate 50, Brillouin spectrum detection in parallel polarization or cross polarization configuration can be achieved.

[0039] Specifically, when both the quarter-wave plate 50 and the polarizer 40 are removed from the optical path, the vertically polarized light passing through the polarization beam splitter 60 remains vertically polarized light after passing through the objective lens 20. When the scattered light from the resonant medium 13 passes through the objective lens 20 and reaches the polarization beam splitter 60, only the horizontally polarized scattered light can be transmitted into the Fabry-Perot interferometer 80. Therefore, at this time, the incident light from the resonant medium 13 is vertically polarized, and the Fabry-Perot interferometer 80 can only capture the horizontally polarized signal in the light scattering signal, that is, the polarization configuration is cross-polarization.

[0040] When the quarter-wave plate 50 and the polarizer 40 are both placed in the optical path, the polarization plane of the polarizer 40 is vertical, and the light passing through the polarizer 40 and the quarter-wave plate 50 is vertically polarized light, and the light passing through the objective lens 20 is still vertically polarized light. Among the scattered light from the resonant medium, only the vertically polarized light scattering signal can pass through the polarizer 40. After passing through the quarter-wave plate, this part of the signal, which is originally vertically polarized, is converted into partially horizontally polarized and partially vertically polarized. The horizontally polarized part can enter the Fabry-Perot interferometer 80 through the polarization beam splitter 60. Therefore, the polarization of the light incident on the resonant medium is vertically polarized at this time, and only the vertically polarized light scattering signal can pass through the polarizer 40 and partially reach the Fabry-Perot interferometer 80, that is, the polarization configuration is parallel polarization.

[0041] With reference to the above embodiments, the quasi-particle resonance enhanced Brillouin spectroscopy system further comprises an objective lens holder 21 and a displacement stage 30. Figure 2

[0042] The objective lens holder 21 is used for mounting the microscope objective 20.

[0043] The displacement stage 30 is used for mounting the objective lens holder 21, and the laser is focused on the resonant medium 13 on the layered material sample 12 with different layers by adjusting the displacement stage 30, so as to measure the interlayer vibration of the layered material sample 12 with different layers.

[0044] The position of the laser spot on the resonant medium 13 can be adjusted by the displacement stage 30.

[0045] With reference to the above embodiments, the quasi-particle resonance enhanced Brillouin spectroscopy system further comprises a rotating sample stage 11, and the rotating sample stage 11 comprises a sample holder 111 and a rotating stage 112. Figure 2 The layered material sample 12 is fixed on the sample holder 111, and the sample holder 111 is movable relative to the rotating stage 112; wherein the light scattering signal of the resonant medium 13 corresponding to different incident angles is detected by rotating the rotating stage 112; and the position of the sample holder 111 on the rotating stage 112 is adjusted so that the laser spot on the resonant medium 13 is located on the central axis of the rotating stage 112.

[0046] Specifically, by rotating the rotating stage 112, the light scattering signal of the resonant medium 13 under oblique incidence can be detected. Compared with normal incidence, the wave vector of the interlayer phonon participating in the inelastic light scattering is different under oblique incidence, so that the dispersion relationship of the interlayer phonon of the layered material 12 can be measured. In order to ensure that the laser spot is always located at the same position of the resonant medium during rotation, the position of the sample holder 111 on the rotating stage 112 needs to be adjusted so that the laser spot on the resonant medium is located on the central axis of the rotating stage 112.

[0047] On the basis of the above embodiments, the quasi-particle comprises plasmons or excitons.

[0048] Further, in the case of plasmons, the resonant medium 13 is a metal particle, and the plasmon energy is tuned by adjusting the particle size; in the case of excitons, the resonant medium 13 is a transition metal carbon disulfide or a twisted layered semiconductor, and the exciton energy can be tuned by changing the temperature and the twist angle.

[0049]

[0050] ​​Based on the above embodiment, the layered material sample 12 comprises graphite with varying numbers of layers, and the resonant medium 13 comprises thin layers of tungsten disulfide, forming a heterojunction between the tungsten disulfide and the graphite. Graphite with varying numbers of layers can be prepared through mechanical exfoliation, and then tungsten disulfide is transferred onto the surface to form a series of heterojunctions of tungsten disulfide and graphite. In one example, the resonant medium 13 can be tuned to an exciton resonance wavelength of approximately 532 nm by varying the temperature or twist angle.

[0051] On the basis of the above embodiment, the layered material sample 12 includes different inter-layer vibration modes divided based on the number of layers covered by a node, and different inter-layer vibration modes have different frequencies and amplitudes.

[0052] Furthermore, the interlayer vibration mode includes a shear mode or a breathing mode.

[0053] According to the embodiments of the present disclosure, different interlayer modes exhibit different frequencies, amplitudes, and linewidths, resulting in different modulations of the quasiparticles. This results in peaks with different frequencies, amplitudes, and linewidths when analyzed by the interferometer. Furthermore, with the aid of a rotating stage, interlayer phonon signals corresponding to the different wave vectors contained in the quasiparticles can be collected.

[0054] In order to more clearly illustrate the phase-resolved Brillouin spectroscopy system provided by the embodiments of the present disclosure, a specific example is given below for illustration.

[0055] In this example, the frequency, relative intensity and line width of the low-frequency interlayer phonons of graphite are obtained by using the quasiparticle resonance enhanced Brillouin system provided by the embodiments of the present disclosure. The photoluminescence process of the quasiparticles modulated by the interlayer vibration of the underlying layered material will contain information about the interlayer vibration. During the resonant luminescence, the interlayer phonon signal will be enhanced. The 532nm laser generated by the laser light source 70 is reflected into the microscope objective 20 through the polarization beam splitter and is focused into the resonant medium 13. The resonant medium 13 is a dense thin layer of tungsten disulfide transferred to the layered sample 12. Its reflection spectrum proves that the resonant wavelength of its excitons is around 532nm. Different vibration modes are divided in the layered sample 12 according to the number of layers contained in a node. These vibration modes have different frequencies and amplitudes, which drive the upper layer of the resonant medium 13 to vibrate, thereby modulating the excitons. When the 532nm laser is focused onto tungsten disulfide, the excitons undergo a resonant photoluminescence process, and the interlayer vibration signal of the underlying layered sample 12 will be captured by the Fabry-Perot interferometer 80 in the form of luminescent sidebands.

[0056] Those skilled in the art will appreciate that the features described in the various embodiments of the present disclosure may be combined and / or coupled in various ways, even if such combinations or couplings are not explicitly described in the present disclosure. In particular, the features described in the various embodiments of the present disclosure may be combined and / or coupled in various ways without departing from the spirit and teachings of the present disclosure. All such combinations and / or couplings fall within the scope of the present disclosure.

[0057] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A quasiparticle resonance enhanced Brillouin spectroscopy system, characterized in that: include: a resonant medium (13) containing tunable luminescent quasiparticles; A layered material sample (12) is bonded to the resonant medium (13), and modulates quasiparticle luminescence in the resonant medium based on interlayer vibration; A laser light source (70) is used to generate laser light, wherein the laser light is focused on the resonant medium (13) and Brillouin scattering occurs with the quasiparticles modulated by the interlayer vibration, thereby generating Brillouin scattered light; wherein the frequency of the quasiparticles in the resonant medium (13) is tuned to resonate with the frequency of the laser light, and the luminescence of the quasiparticles is enhanced by the resonance, thereby enhancing the Brillouin signal of the interlayer vibration of the layered material sample (12) carried by the quasiparticles; A Fabry-Perot interferometer (80) analyzes the Brillouin scattered light and outputs Brillouin scattered light with a preset frequency; In the case where the quasiparticle is a plasmon, the resonant medium (13) is a metal particle, and the plasmon energy is tuned by adjusting the particle size; In the case where the quasiparticle is an exciton, the resonant medium (13) is a transition metal carbon disulfide or a twisted layered semiconductor, and the exciton energy can be tuned by changing the temperature and the twist angle; The layered material sample (12) is divided into different interlayer vibration modes based on the number of layers contained in a node, and different interlayer vibration modes have different frequencies and amplitudes.

2. The system according to claim 1, wherein: The system further comprises: a polarization beam splitter (60) for reflecting a vertically polarized component in the laser light generated by the laser light source (70); A microscope objective lens (20) is used to focus the vertically polarized laser light onto the resonance medium (13).

3. The system according to claim 2, characterized in that The system further comprises: A polarization beam splitting component comprises a polarizer (40) and a λ / 4 wave plate (50), and is used for linkage with the polarization beam splitter (60) of the incident light path. By inserting or removing the polarizer (40) and the λ / 4 wave plate (50), Brillouin spectrum detection in a parallel polarization or cross polarization configuration is achieved.

4. The system according to claim 2, wherein: The system further comprises: An objective lens holder (21) for mounting the microscope objective lens (20); A displacement stage (30) is used to mount the objective lens holder (21), and the laser is focused onto the resonant medium (13) on the layered material samples (12) with different numbers of layers by adjusting the displacement stage (30) to measure the interlayer vibration of the layered material samples (12) with different numbers of layers.

5. The system according to claim 1, wherein: The system further comprises: A rotating sample stage (11), the rotating sample stage (11) comprising a sample holder (111) and a rotating stage (112), the layered material sample (12) being fixed on the sample holder (111), and the sample holder (111) being movable relative to the rotating stage (112); wherein the rotating stage (112) is rotated to detect light scattering signals of a resonance medium (13) corresponding to different incident angles; and the position of the sample holder (111) on the rotating stage (112) is adjusted so that the light spot of the resonance medium (13) is located on the central axis of the rotating stage (112).

6. The system according to any one of claims 1 to 5, characterized in that: The quasiparticles include plasmons or excitons.

7. The system according to any one of claims 1 to 5, characterized in that: The layered material sample (12) includes graphite with different numbers of layers, and the resonance medium (13) includes disulfide, wherein the disulfide and the graphite form a heterojunction.

8. The system according to claim 1, wherein: The interlayer vibration mode includes a shear mode or a breathing mode.

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