Spectroscopic device

Abstract

The application provides a spectrum device, which comprises a first light path unit configured to excite a sample into a non-equilibrium state; a second light path unit configured to detect reflection spectrum information of a reflection spectrum signal emitted by the sample in the non-equilibrium state; and a measurement unit configured to measure the reflection spectrum information. According to the embodiment of the application, the spectrum device can realize time, energy and momentum information of a sample transient state or non-equilibrium state, and can be used for studying exciton and photon transient state interaction in a low-dimensional semiconductor.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of quantum materials, and in particular, to a spectrum device. BACKGROUND

[0002] Under the excitation of ultrafast laser, the electronic system of a substance enters a non-equilibrium state instantaneously, and through complex interactions, the system exhibits many physical effects, such as magneto-optical effect, quantum phase transition, high harmonic radiation, etc. Ultrafast time-resolved technology is an important means to study the time evolution process of various interactions in solid materials and to realize non-equilibrium phase transition.

[0003] Micro-area angle-resolved spectrum technology is used to measure the fluorescence, Raman, absorption spectrum, momentum information, etc. of nanomaterials, which can reflect the photoelectric response, structural phase transition, quantum control, etc. of low-dimensional quantum materials, and plays an important supporting role in the fields of preparation of low-dimensional nanolaser, quantum simulation based on nanometer semiconductor, and research of new high-speed transmission quantum materials, etc.

[0004] Generally, time-resolved spectrum detection devices can only measure macroscopic solid or liquid samples, and cannot measure micro-nano size samples such as two-dimensional materials; they do not have angle resolution capability and are difficult to meet the testing needs of nanomaterials and low-dimensional quantum materials. Generally, angle-resolved spectrum detection devices can only realize steady-state spectrum measurement, and the instantaneous response process of carriers is submerged in the long integration signal, so that transient and non-equilibrium state measurement cannot be realized. In addition, the device does not have time resolution and polarization detection capability, and the sample is limited to room temperature, so that low-temperature, variable-temperature, magnetic field and electric field measurement cannot be realized. SUMMARY

[0005] The present application aims to provide a spectrum device to solve at least one of the above problems.

[0006] According to an aspect of the present application, a spectrum device is provided, comprising: a first optical path unit configured to excite a sample to a non-equilibrium state; a second optical path unit configured to detect reflection spectrum information of a reflection spectrum signal emitted by the sample in the non-equilibrium state; and a measurement unit configured to measure the reflection spectrum information.

[0007] According to some embodiments, the spectrum device further comprises a laser unit configured to divide laser pulses into pump light and probe light, and send the pump light to the first optical path unit and the probe light to the second optical path unit, respectively.

[0008] According to some embodiments, there is an optical path difference between the pump light in the first optical path unit and the probe light in the second optical path unit.

[0009] According to some embodiments, the first optical path unit or the second optical path unit includes a delay subunit configured to generate the optical path difference.

[0010] According to some embodiments, the reflectance spectral information includes reflectance spectral time, and the spectral device further includes a computer unit, which is connected to the measurement unit and the delay subunit respectively. The computer unit is configured to control the measurement unit and the delay subunit in a coordinated manner to measure the reflectance spectral time.

[0011] According to some embodiments, the measurement unit includes a 4F measurement subunit configured to convert the reflection spectral signal from real space to momentum space.

[0012] According to some embodiments, the reflectance spectral information includes reflectance spectral energy information and reflectance spectral momentum information, and the measurement unit further includes a charge-coupled device configured to collect the reflectance spectral energy information and the reflectance spectral momentum information.

[0013] According to some embodiments, the reflectance spectral information further includes reflectance spectral spatial information, and the 4F measurement subunit includes a confocal subsystem configured to measure the reflectance spectral spatial information.

[0014] According to some embodiments, the reflection spectral information includes reflection spectral polarization information, and the measurement unit further includes a linear polarizer subunit configured to measure the reflection spectral polarization information.

[0015] According to some embodiments, the sample is placed in a vacuum environment, and the temperature of the sample is adjustable.

[0016] According to some embodiments of this application, the spectroscopic device can realize the time, energy and momentum information of a sample in transient or non-equilibrium states, and can be used to study the transient interactions of excitons and photons in low-dimensional semiconductors.

[0017] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. The above and other objectives, features, and advantages of this application will become more apparent by referring to the accompanying drawings and describing exemplary embodiments in detail.

[0019] Figure 1 A block diagram of a spectroscopic device according to an example embodiment of this application is shown.

[0020] Figure 2 A schematic diagram of a spectroscopic device according to an example embodiment of this application is shown. Detailed Implementation

[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0022] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, apparatus, or operations may be employed. In these cases, well-known structures, methods, apparatuses, implementations, materials, or operations will not be shown or described in detail.

[0023] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0024] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0025] The specific embodiments according to this application will now be described in detail with reference to the accompanying drawings.

[0026] Figure 1 A block diagram of a spectral device according to an example embodiment of this application is shown, such as Figure 1 The spectral device shown includes a first optical path unit 101, a second optical path unit 103, and a measurement unit 105.

[0027] According to an embodiment of this application, the first optical path unit 101 is configured to excite the sample to a non-equilibrium state; the second optical path unit 103 is configured to detect the reflection spectral information of the reflection spectral signal emitted by the sample in the non-equilibrium state; and the measurement unit 105 is configured to measure the reflection spectral information.

[0028] In a specific embodiment, the spectral device further includes a laser unit configured to split a laser pulse into a pump light and a probe light, and to send the pump light to the first optical path unit and the probe light to the second optical path unit, respectively.

[0029] According to some embodiments, there is an optical path difference between the pump light in the first optical path unit and the probe light in the second optical path unit.

[0030] In a specific embodiment, the first optical path unit or the second optical path unit includes a delay sub-unit configured to generate the optical path difference.

[0031] For example, in the first or second optical path unit, the pump light or probe light is passed through at least one delay sub-unit so that the pump light and probe light have an optical path difference in space.

[0032] According to some embodiments, the delay subunit includes, but is not limited to, a displacement stage and a delay line.

[0033] According to an embodiment of this application, the reflectance spectral information includes reflectance spectral time, and the spectral device further includes a computer unit. The computer unit is connected to the measurement unit and the delay subunit respectively. The computer unit is configured to control the measurement unit and the delay subunit in a coordinated manner to measure the reflectance spectral time.

[0034] In some embodiments, the reflectance spectral information includes reflectance spectral momentum information, and the measurement unit includes a 4F measurement subunit configured to convert the reflectance spectral signal from real space to momentum space, so that the measurement unit can measure the reflectance spectral momentum information of the reflectance spectral signal.

[0035] According to an embodiment of this application, the reflectance spectral information includes reflectance spectral energy information and reflectance spectral momentum information, and the measurement unit further includes a charge-coupled device configured to collect the reflectance spectral energy information and the reflectance spectral momentum information.

[0036] In a specific embodiment, the charge-coupled device includes a CCD, which is a two-dimensional pixel array. One dimension represents the angle of collection, corresponding to the momentum information of the reflected spectrum, and the other dimension represents the wavelength of collection, corresponding to the energy information of the reflected spectrum.

[0037] In a specific embodiment, the spectroscopic device further includes a microscope objective for focusing probe light or pump light onto the sample surface; the measurement unit includes a spectrometer, and the 4F measurement subunit includes lens L1 and lens L2, wherein lens L1 and lens L2 are confocal. According to some embodiments, the distance between lens L1 and the spectrometer slit is its focal length f1, and the distance between lens L2 and the microscope objective is its focal length f2.

[0038] According to an embodiment of this application, the reflectance spectral information further includes reflectance spectral spatial information, and the 4F measurement subunit includes a confocal subsystem configured to measure the reflectance spectral spatial information.

[0039] In a specific embodiment, a confocal subsystem is integrated into the 4F measurement subunit, thereby enabling the 4F measurement subunit to measure both the momentum information of the reflection spectrum and spatial resolution, for measuring the spatial information of the reflection spectrum. In some embodiments, adding an aperture stop for spatial filtering on the focal plane between the two lenses can give the spectroscopic device a spatial resolution on the order of micrometers.

[0040] According to an embodiment of this application, the reflection spectral information includes reflection spectral polarization information, and the measurement unit further includes a linear polarizer subunit configured to measure the reflection spectral polarization information.

[0041] In a specific embodiment, the sample is placed in a vacuum environment, and the temperature of the sample is adjustable.

[0042] according to Figure 1 The illustrated embodiment shows that the spectroscopic device can realize the time, energy, and momentum information of a sample in transient or non-equilibrium states. This information can be used to study the transient interactions between excitons and photons in low-dimensional semiconductors, achieving energy-momentum property characterization and energy state manipulation. Property characterization refers to the fundamental characterization of matter, such as X-ray diffraction analysis, X-ray transmission electron microscopy, scanning electron microscopy and electron probe microscopy, photoelectron spectroscopy, and Auger electron spectroscopy. In this application, property characterization includes physical processes such as energy, momentum, and carrier time evolution.

[0043] According to other embodiments, Figure 1 The temperature of the sample in the spectroscopic device shown is adjustable. The spectroscopic device is not only suitable for measuring the spectral information of the sample at room temperature, but also suitable for measuring the spectral information of the sample in low temperature, magnetic field and electric field and other occasions.

[0044] Figure 2 A schematic diagram of a spectroscopic device according to an example embodiment of this application is shown, such as Figure 2The spectroscopic apparatus shown includes a femtosecond laser 1, beam splitters 2-1, 2-2, 2-3, high-reflectivity mirrors 3-1, 3-2, 3-3, focusing lenses 4-1, 4-2, linear polarizers 5-1, 5-2, half-wave plates 6-1, 6-2, quarter-wave plate 8, time delay line 7, 4F system 11, imaging system 15, titanium sapphire or calcium fluoride crystal 16, spectrometer 13, low-temperature vacuum chamber and sample stage 10, optical parametric amplifier 17, and sample 18.

[0045] like Figure 2 The femtosecond laser 1 generates femtosecond laser pulses, which are then split into two beams—a pump beam and a probe beam—by a planar beam splitter 2-1. The pump beam undergoes wavelength conversion via an optical parametric amplifier 17 to obtain a wavelength-tunable pump beam.

[0046] In a specific embodiment, the optical parametric amplifier 17 utilizes a nonlinear crystal to achieve laser wavelength conversion.

[0047] In the pump light path, the pump light sequentially passes through a high-reflectivity mirror 3-1, a linear polarizer 5-1, a half-wave plate 6-1, a planar beam splitter 2-2, a stereo beam splitter 2-3, a quarter-wave plate 8, and a microscope objective 9, and is focused onto the sample surface 10. By adjusting the relative angles between 5-1, 6-1, and 8, the polarization characteristics of the light are controlled, and this is used to excite the sample to a non-equilibrium state. The microscope objective 9 focuses the light spot on the sample surface to the micrometer level, achieving micro-area detection capability. The combined use of 5-1, 6-1, and 8 can achieve left-handed circularly polarized light, right-handed circularly polarized light, and linearly polarized laser output.

[0048] In the probe light path, the probe light sequentially passes through lens groups 4-1 and 4-2, a titanium sapphire or calcium fluoride crystal 16, a delay line 7, a high-reflectance mirror 3-2, a flat beam splitter 2-2, a cubic beam splitter 2-3, a quarter-wave plate 8, and a microscope objective 9, and is focused onto the sample surface to detect the reflectance spectrum information of the sample surface. The titanium sapphire or calcium fluoride crystal 16 is used to generate supercontinuous white light, the delay line 7 is used to generate the delay time between the probe light and the pump light, and the quarter-wave plate 7 can adjust the polarization characteristics of the probe light.

[0049] like Figure 2 As shown, delay line 7 is connected to computer 14 to control the optical path difference between pump light and probe light, thereby achieving time-resolved detection.

[0050] The 4F system 11 is used to measure the near and far fields of the sample's reflectance spectrum signal, converting real space information to momentum space information through Fourier transform. Real space refers to the vacuum space where the size and shape of an object are determined by measurement. Utilizing the 4F optical imaging function, this angular resolution system 11 can be integrated with a confocal system, giving it spatial resolution capabilities. In a specific embodiment, an aperture stop is placed on the focal plane between the two lenses for spatial filtering, thereby enabling the 4F system 11 to achieve micrometer-level spatial resolution.

[0051] According to embodiments of this application, a quarter-wave plate 8, half-wave plates 6-1 and 6-2, and linear polarizers 5-1 and 5-2 are used to detect polarization characteristics in spectral information.

[0052] In some embodiments, the sample stage 10 is placed in a low-temperature vacuum chamber to enable spectroscopic measurements of the sample with adjustable sample temperature in a vacuum environment.

[0053] In a specific embodiment, the imaging system 15 includes a lens and a camera, which can be used to observe the sample and determine the position of the light spot hitting the sample surface.

[0054] like Figure 2 As shown, the spectral signal measured by time resolution, angle resolution, and polarization passes through the bandpass filter 12 to filter out the reflected pump light, allowing only the probe light to pass through and enter the spectrometer 13, where the spectrometer 13 collects the reflection spectrum information such as time, energy, and momentum.

[0055] In some embodiments, the spectrometer 13 and the delay line 7 are linked and controlled by the computer 14 to achieve automatic acquisition of time-resolved spectra.

[0056] like Figure 2 The spectroscopic apparatus shown is a system integrating time resolution, micro-area angular resolution, and polarization measurement. It can perform spectroscopic measurements of the fluorescence, reflectance, wavelength / energy, and momentum information of a sample, that is, it can measure the time, energy, and momentum information of the sample. Among them, reflection is the reflection of light of the same wavelength after it is incident; fluorescence is the emission of fluorescence of other wavelengths after it is incident.

[0057] Compared to existing time-resolved spectrometers, Figure 2 The spectroscopic device shown possesses micro-area detection capabilities within a microscopic system, enabling the measurement of micro- and nano-scale samples such as two-dimensional materials. Simultaneously, it features angular resolution, meeting the testing requirements for nanomaterials and low-dimensional quantum materials. Compared to existing angular-resolution spectrometers, this device offers time resolution and polarization detection capabilities, enabling transient and non-equilibrium state measurements. Furthermore, the sample testing environment is not limited to room temperature; it is also applicable in low-temperature, magnetic field, and electric field environments.

[0058] Those skilled in the art will understand that the above modules can be distributed in the device as described in the embodiments, or they can be modified accordingly and placed in one or more devices that are unique to this embodiment. The modules in the above embodiments can be combined into one module, or they can be further divided into multiple sub-modules.

[0059] According to an embodiment of this application, a computer program is proposed, including a computer program or instructions, which, when executed by a processor, can perform the methods described above.

[0060] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. Furthermore, any changes or modifications made by those skilled in the art based on the ideas of this application, and on the specific implementation methods and application scope of this application, are all within the scope of protection of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A spectroscopic device, characterized in that, The spectroscopic apparatus includes a femtosecond laser, a beam splitter, a high-reflectivity mirror, a focusing lens, a linear polarizer, a half-wave plate, a quarter-wave plate, a time delay line, a 4F system, an imaging system, a titanium sapphire or calcium fluoride crystal, a spectrometer, a low-temperature vacuum chamber and sample stage, an optical parametric amplifier, and a sample, including: A laser unit configured to split a laser pulse into a pump beam and a probe beam; The first optical path unit is configured to excite the sample to a non-equilibrium state; The second optical path unit is configured to detect the reflection spectrum information of the reflection spectrum signal emitted by the sample in a non-equilibrium state; The measurement unit is configured to measure the reflectance spectral information; in, The laser unit is further configured to send the pump light to the first optical path unit and the probe light to the second optical path unit, respectively; The measurement unit includes a 4F measurement subunit configured to convert the reflection spectral signal from real space to momentum space. The spectral signal, after time-resolved, angle-resolved, and polarization-measured measurements, passes through a bandpass filter to remove the reflected pump light, allowing only the probe light to pass through before entering the spectrometer. The spectrometer then collects the time, energy, and momentum reflection spectral information of the reflection spectrum.

2. The spectroscopic device according to claim 1, characterized in that, There is an optical path difference between the pump light in the first optical path unit and the probe light in the second optical path unit.

3. The spectroscopic device according to claim 2, characterized in that, The first optical path unit or the second optical path unit includes a delay subunit configured to generate the optical path difference.

4. The spectroscopic device according to claim 3, characterized in that, The reflectance spectral information includes reflectance spectral time. The spectral device also includes a computer unit, which is connected to the measurement unit and the delay subunit respectively. The computer unit is configured to control the measurement unit and the delay subunit in a coordinated manner to measure the reflectance spectral time.

5. The spectroscopic device according to claim 1, characterized in that, The reflection spectral information includes reflection spectral energy information and reflection spectral momentum information. The measurement unit also includes a charge-coupled device configured to collect the reflection spectral energy information and the reflection spectral momentum information.

6. The spectroscopic device according to claim 1, characterized in that, The reflectance spectral information also includes reflectance spectral spatial information, and the 4F measurement subunit includes a confocal subsystem configured to measure the reflectance spectral spatial information.

7. The spectroscopic device according to claim 1, characterized in that, The reflection spectrum information includes reflection spectrum polarization information, and the measurement unit further includes a linear polarizer unit configured to measure the reflection spectrum polarization information.

8. The spectroscopic device according to claim 1, characterized in that, The sample is placed in a vacuum environment, and the temperature of the sample is adjustable.

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