Quasi-particle resonance enhanced Brillouin spectrum system

Abstract

Embodiments of the present disclosure provide a quasi-particle resonance enhanced Brillouin spectroscopy system, comprising: a resonance medium comprising tunable luminescent quasi-particles; the layered material sample is attached to the resonance medium, and quasi-particles in the resonance medium are modulated to emit light based on interlayer vibration; the laser light source is used for generating laser, the laser is focused on the resonance medium to generate Brillouin scattering with the quasi-particles modulated by interlayer vibration, and Brillouin scattering light is generated; wherein the frequency of the quasi-particles of the resonance medium is tuned to resonate with the frequency of the laser, and luminescence of the quasi-particles is enhanced through resonance, so that a Brillouin signal of interlayer vibration of a layered material sample carried by the quasi-particles is obtained through enhancement; and the Fabry-Perot interferometer is used for analyzing the Brillouin scattered light and outputting the 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] The mechanical interaction of nanoscale interfaces carries key information such as atomic-level interface structure, thermal conductivity, and optoelectronic properties, but it cannot be directly measured by classical vibrational spectroscopy because of its very limited electron-phonon coupling effect. Taking ultra-low-frequency shear or breathing phonons in layered van der Waals materials as an example, the phonon vibration mode with collective co-directional motion of atomic layers contains unique information about the global structure of the crystal and hidden interfaces, but cannot produce detectable electric dipole radiation because the changes in polarizability between adjacent layers cancel each other out. In addition, the interlayer vibration modes in thicker layered materials are densely distributed, and the frequency of low-frequency modes is very low. Taking a 100-layer layered material as an example, the low-frequency mode is about 1 / 100 of the bulk mode frequency, and the resolution required to distinguish different modes is 100 times that of a 2-layer sample. Therefore, it is necessary to develop a new high-resolution vibrational spectroscopy technique to detect low-frequency interlayer vibration 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] The embodiments of the present disclosure provide a quasiparticle resonance enhanced Brillouin spectroscopy system, comprising: a resonant medium, comprising tunable luminescent quasiparticles; a layered material sample, which is bonded to the resonant medium and modulates the quasiparticles in the resonant medium to emit light based on interlayer vibration; a laser light source, which is used to generate laser light, and the laser light is focused on the resonant medium to generate Brillouin scattering with the quasiparticles modulated by the interlayer vibration to generate 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 vibration 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 for focusing the vertically polarized laser light on the resonance 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 work in conjunction with a polarization beam splitter in an incident light path, and to achieve Brillouin spectrum detection in a parallel polarization or cross-polarization configuration by inserting or removing the polarizer and the 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 also includes: a rotating sample stage, the rotating sample stage includes a sample holder and a rotating stage, the layered material sample is fixed on the sample holder, and the sample holder can move relative to the rotating stage; wherein, the light scattering signal of the resonance medium corresponding to different incident angles is detected by rotating the rotating stage; and the light spot of the resonance 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 quasiparticle is a plasmon, the resonant medium is a metal particle, and the plasmon energy is tuned by adjusting the particle size; when the quasiparticle is an exciton, the resonant medium is a transition metal carbon disulfide or a twisted layered semiconductor, and the exciton energy can be tuned by changing the temperature or the twist angle.

[0011] According to an embodiment of the present disclosure, the layered material sample is distributed with graphite of 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 the 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 embodiment of the present disclosure, the laser light generated by the laser light source is focused on the surface of the resonant medium and scatters light with the quasiparticles, and the photoluminescence of the quasiparticles modulated by the interlayer vibration of the underlying layered material is resonantly enhanced, resulting in the enhancement of the signal of the interlayer vibration, which is detected in the form of a series of peaks in the quasiparticle photoluminescence intensity-frequency relationship after being analyzed by the Fabry-Perot interferometer. The frequencies, amplitudes and line widths of different interlayer modes are different, so the quasiparticles are modulated differently, and peaks with different frequencies, amplitudes and line widths appear after being analyzed by the interferometer. In addition, with the help of a rotating stage, interlayer phonon signals corresponding to 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 The structure of the quasiparticle resonance enhanced Brillouin spectroscopy system according to an embodiment of the present disclosure is schematically shown;

[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-resonance 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 exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, 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 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 existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0022] All terms (including technical and scientific terms) used herein 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 using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression 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] In view of the conventional Brillouin spectroscopy system, the present invention proposes a quasiparticle resonance enhanced Brillouin spectroscopy system, which adopts Brillouin spectroscopy technology and combines the technology of attaching a resonant medium to a layered material sample to achieve the resonance enhancement of interlayer phonons. The present invention can provide an easy-to-build, low-cost quasiparticle resonance enhanced Brillouin spectroscopy system, which can detect shear mode and breathing mode phonons of layered materials and study the mechanical interaction of nanoscale interfaces. The following is an introduction in conjunction with specific embodiments.

[0025] Figure 1 The structure of a quasiparticle resonance enhanced Brillouin spectroscopy system according to an embodiment of the present disclosure is schematically shown.

[0026] like Figure 1 As shown, the quasiparticle resonance enhanced Brillouin spectroscopy system may include: a resonance medium 13 , a layered material sample 12 , a laser light source 70 and a Fabry-Perot interferometer 80 .

[0027] The resonant medium 13 contains tunable luminescent quasiparticles.

[0028] The layered material sample 12 is bonded to the resonance medium 13, and the quasiparticle light emission in the resonance medium is modulated based on interlayer vibration.

[0029] The laser light source 70 is used to generate laser light. The laser light is focused on the resonant medium 13 and undergoes Brillouin scattering with the quasiparticles modulated by the interlayer vibration to generate Brillouin scattered light. The frequency of the quasiparticles in the resonant medium 13 is tuned to resonate with the frequency of the laser light. The quasiparticle light emission is enhanced by resonance to enhance the Brillouin signal of the interlayer vibration of the layered material sample 12 carried by the quasiparticles.

[0030] The Fabry-Perot interferometer 80 analyzes the Brillouin scattered light and outputs the Brillouin scattered light with a preset frequency. After the light scattering signal of the quasiparticle is analyzed by the Fabry-Perot interferometer 80, the interlayer vibration mode carried by the quasiparticle appears as a peak on the intensity-frequency spectrum.

[0031] According to the quasiparticle resonance enhanced Brillouin spectroscopy system of the embodiment of the present disclosure, the laser light generated by the laser light source is focused onto the surface of the resonant medium and scatters light with the quasiparticles, and the photoluminescence of the quasiparticles modulated by the interlayer vibration of the underlying layered material is resonantly enhanced, resulting in the enhancement of the signal of the interlayer vibration, which is detected as a series of peaks in the quasiparticle photoluminescence intensity-frequency relationship after being analyzed by a Fabry-Perot interferometer.

[0032] Figure 2 The structure of a quasiparticle resonance enhanced Brillouin spectroscopy system according to another embodiment of the present disclosure 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 to form a laser spot, which resonantly excites 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 are used to work in conjunction with a polarization beam splitter 60 of the incident light path. By inserting or removing the polarizer 40 and the quarter wave plate 50, Brillouin spectrum detection in a parallel polarization or cross polarization configuration is achieved.

[0039] Specifically, when 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 is still vertically polarized light after passing through the objective lens 20. When the scattered light of the resonance medium 13 passes through the objective lens 20 to the polarization beam splitter 60, only the horizontally polarized scattered light can be transmitted to the Fabry-Perot interferometer 80. Therefore, at this time, the incident light of the resonance 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 of the resonant medium, only the vertically polarized light scattering signal can pass through the polarizer 40, and after passing through the quarter wave plate, this part of the signal, which is itself vertically polarized, is converted into partly horizontally polarized and partly vertically polarized. Among them, the horizontally polarized part can enter the Fabry-Perot interferometer 80 through the polarization beam splitter 60. Therefore, at this time, the polarization of the light incident on the resonant medium is vertically polarized, 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] Continue reading Figure 2 On the basis of the above-mentioned embodiment, the quasiparticle resonance enhanced Brillouin spectroscopy system further includes: an objective lens frame 21 and a translation stage 30 .

[0042] The objective lens holder 21 is used to install the microscope objective lens 20 .

[0043] The translation stage 30 is used to install the objective lens holder 21. By adjusting the translation stage 30, the laser is focused on the resonance medium 13 on the layered material samples 12 with different numbers of layers to measure the interlayer vibration of the layered material samples 12 with different numbers of layers.

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

[0045] Continue reading Figure 2 On the basis of the above-mentioned embodiment, the quasiparticle resonance enhanced Brillouin spectroscopy system further includes: a rotating sample stage 11 , and the rotating sample stage 11 includes a sample holder 111 and a rotating stage 112 .

[0046] The layered material sample 12 is fixed on a sample holder 111, and the sample holder 111 can move relative to the rotating table 112; wherein, the light scattering signal of the resonance medium 13 corresponding to different incident angles is detected by rotating the rotating table 112; and the light spot of the resonance medium 13 is located on the central axis of the rotating table 112 by adjusting the position of the sample holder 111 on the rotating table 112.

[0047] Specifically, by rotating the rotating stage 112, the light scattering signal of the resonant medium 13 at oblique incidence can be detected. Compared with normal incidence, the wave vector of the interlayer phonons participating in the inelastic light scattering at oblique incidence is different, so the dispersion relation of the interlayer phonons of the layered material 12 can be measured. In order to ensure that the light spot is always located at the same position of the resonant medium during the rotation process, it is necessary to adjust the position of the sample holder 111 on the rotating stage 112 so that the light spot on the resonant medium is exactly located on the central axis of the rotating stage 112.

[0048] Based on the above embodiments, the quasiparticles include plasmons or excitons.

[0049] Furthermore, when the quasiparticle is a plasmon, the resonant medium 13 is a metal particle, and the plasmon energy is tuned by adjusting the particle size; when 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.

[0050] On the basis of the above-mentioned embodiment, the layered material sample 12 is distributed with different numbers of graphite layers, and the resonant medium 13 includes a thin layer of tungsten disulfide, and the tungsten disulfide and the graphite form a heterojunction. Graphite with various numbers of layers can be prepared by mechanical exfoliation, and then tungsten disulfide is transferred on its surface to form a series of heterojunctions of tungsten disulfide and graphite. In one example, the resonant medium 13 can tune its exciton resonance wavelength to around 532nm by changing the temperature or twisting angle.

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

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

[0053] According to the embodiments of the present disclosure, the frequencies, amplitudes and line widths of different interlayer modes are different, so the quasiparticles are modulated differently, and peaks with different frequencies, amplitudes and line widths appear after being analyzed by the interferometer. In addition, with the help of a rotating stage, interlayer phonon signals corresponding to 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 listed below for illustration.

[0055] In this example, the frequency, relative intensity and line width of low-frequency interlayer phonons of graphite are obtained by using the quasi-particle resonance enhanced Brillouin system provided by the embodiment of the present disclosure. The photoluminescence process of the quasi-particles 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, and its reflection spectrum proves that the resonant wavelength of its isoexcitons 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 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 a luminescent sideband.

[0056] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0057] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of 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 attached to the resonance medium (13) to modulate the luminescence of quasiparticles in the resonance 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) to generate Brillouin scattering 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, so as to enhance 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.

2. The system according to claim 1, characterized in that The system further comprises: A polarization beam splitter (60), used for reflecting a vertical polarization 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 resolution component comprises a polarizer (40) and a quarter-wave plate (50), which is used to work in conjunction with the polarization beam splitter (60) of the incident light path, and to achieve Brillouin spectrum detection in a parallel polarization or cross-polarization configuration by inserting or removing the polarizer (40) and the quarter-wave plate (50).

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

5. The system according to claim 1, characterized in that The system further comprises: A rotating sample stage (11), the rotating sample stage (11) comprising a sample holder (111) and a rotating table (112), the layered material sample (12) being fixed on the sample holder (111), and the sample holder (111) being movable relative to the rotating table (112); wherein the rotating table (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 table (112) is adjusted so that the light spot of the resonance medium (13) is located on the central axis of the rotating table (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 claim 6, characterized in that 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 transition metal carbon disulfide or a twisted layered semiconductor, and the exciton energy can be tuned by changing the temperature or the twist angle.

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

9. The system according to claim 8, characterized in that The layered material sample (12) comprises different interlayer vibration modes divided based on the number of layers covered by a node, and different interlayer vibration modes have different frequencies and amplitudes.

10. The system according to claim 9, characterized in that The interlayer vibration mode includes a shear mode or a breathing mode.

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