Transient absorption spectroscopy detection system

Abstract

This application relates to a transient absorption spectroscopy detection system. The microscopic imaging module of this system can compress the spot size of the target light emitted from the output light module to the micrometer scale; the temperature displacement control module can provide the user with the required temperature environment and can also be moved to the sample chamber to ensure that the target light spot can cover the micro-area to be measured. Thus, based on the coordinated work of the output light module, microscopic imaging module, temperature displacement control module, and spectrometer, the detection dimensions of transient absorption spectroscopy are expanded, enabling in-situ study of the evolution of non-equilibrium dynamics of materials with temperature at the micro-nano scale. In particular, it provides a reliable detection system for non-contact, non-destructive detection of charge density wave phase transitions in two-dimensional materials, and provides cross-scale, multi-parameter key experimental data support for the design and optimization of two-dimensional materials and quantum devices.

Description

Technical Field

[0001] This application relates to the field of transient absorption spectroscopy detection technology, and in particular to a transient absorption spectroscopy detection system. Background Technology

[0002] When detecting CDW (Charge Density Wave) phase transitions in materials, contact measurement methods are often used. These methods rely on direct contact or very close interaction between the probe and the sample, which introduces external mechanical pressure or electric fields, thus disturbing the CDW phase and affecting the accuracy of the phase transition behavior. Therefore, there is a problem of insufficient detection accuracy in detecting CDW phase transitions in materials. Summary of the Invention

[0003] Therefore, it is necessary to provide a transient absorption spectroscopy detection system with high detection accuracy.

[0004] A transient absorption spectroscopy detection system, comprising:

[0005] The output light module is used to output target light, which is the beam of pump light and probe light combined after the optical path difference is within a preset floating range;

[0006] The microscopic imaging module is placed inside the spectral detection chamber. The microscopic imaging module is used to receive the target light, and the optical path of the target light is collinear with the optical axis of the microscope group in the microscopic imaging module.

[0007] The temperature displacement control module is used to maintain the temperature inside the sample chamber within a preset temperature range and to control the position of the sample chamber so that the microscopic imaging module can project the received target light onto the micro-area of ​​the sample to be tested inside the sample chamber.

[0008] A spectrometer is used to acquire spectral signals of the micro-region to be measured, and based on the spectral signals, to obtain the transient absorption spectrum of the micro-region to be measured within a preset temperature range.

[0009] In one embodiment, the microscopic imaging module includes: a photosensitive imaging module, a sampling cube, and a microscope group; the microscope group includes a first microscope and a second microscope;

[0010] The sampling cube is placed in the optical path of the target light. The sampling cube is used to couple the imaging path of the photosensitive imaging module and the imaging path of the first microscope to the optical path of the target light, so that the spot imaging of the target light and the micro-area imaging of the micro-area to be measured can be observed simultaneously in the photosensitive imaging module.

[0011] The first microscope is set in the optical path of the target light emitted from the sampling cube. The first microscope is used to magnify the micro-area to be measured and to focus the target light on the micro-area to be measured.

[0012] The second microscope is set in the optical path of the target light emitted from the first microscope and is located between the sample to be tested and the spectrometer. The second microscope is used to restore the light focused on the micro-area to be tested into parallel light and project it onto the spectrometer.

[0013] The first and second microscopes are not in contact with the sample chamber; the optical axes of the first and second microscopes are collinear with the optical path of the target light.

[0014] In one embodiment, the microscopic imaging module further includes:

[0015] Bright-field module, used to provide illumination for micro-area imaging of the micro-area to be measured;

[0016] The sampling cube is used to couple the imaging path of the photosensitive imaging module, the imaging path of the first microscope, and the optical path of the bright field module to the optical path of the target light.

[0017] In one embodiment, the emitted light module includes:

[0018] A laser, used to output pulsed laser light; the laser is placed outside the spectral detection chamber.

[0019] A beam splitter is used to receive pulsed laser light from a laser and output a first seed light and a second seed light; wherein the first seed light is the seed light for the probe light and the second seed light is the seed light for the pump light.

[0020] An optical parametric amplifier is placed in the optical path of the second seed light. The optical parametric amplifier is used to convert the second seed light into pump light within the target wavelength range.

[0021] An optical path adjustment module is set in the optical path of the first seed light and is used to adjust the optical path of the first seed light.

[0022] The first filter is placed in the optical path of the pump light emitted from the optical parametric amplifier. The first filter is used to adjust the energy of the pump light.

[0023] A focusing convex lens is placed in the optical path of the first seed light emitted from the optical path adjustment module. The focusing convex lens is used to focus the first seed light before it is emitted.

[0024] A nonlinear crystal is placed in the optical path of the light emitted from the focusing convex lens. The nonlinear crystal is used to convert the received light into focused probe light.

[0025] A band-stop filter is placed in the optical path of the focused probe light emitted from the nonlinear crystal.

[0026] A parabolic mirror is placed in the optical path of the focused probe light emitted from the filter. The parabolic mirror is used to restore the focused probe light into a parallel probe light; the parallel probe light is the probe light in the target light.

[0027] The second filter is placed in the optical path of the probe light emitted from the parabolic mirror, and the second filter is used to adjust the energy of the probe light;

[0028] A beam combiner is positioned in the optical path of the pump light emitted from the first filter and the optical path of the probe light emitted from the second filter. The beam combiner is used to coincide the optical paths of the pump light and the probe light.

[0029] In one embodiment, the transient absorption spectroscopy detection system further includes:

[0030] A control terminal is connected to an optical path adjustment module. The control terminal is used to acquire and drive the optical path adjustment module according to the control instructions, so that the optical path adjustment module adjusts the optical path of the first seed light.

[0031] In one embodiment, in the beam splitter, the splitting ratio of the first seed light is smaller than that of the second seed light.

[0032] In one embodiment, the target sidewall of the sample chamber is a transparent window, and the two transparent windows arranged opposite each other are made of the same material; wherein, the target sidewall is the sidewall located in the optical path of the target light;

[0033] The sample to be tested is placed between a sample slide and a glass slide in the sample chamber. The sample slide has a first hole, and the glass slide has a second hole. The projection of the first hole onto the glass slide along the direction of the target light coincides with the second hole. The projection of the micro-area to be tested onto the glass slide along the direction of the target light is located in the second hole.

[0034] In one embodiment, the sample chamber also includes a sample cover sheet;

[0035] The cover plate, the glass slide, and the sample are stacked in sequence. A third hole is made in the cover plate. The projection of the third hole on the glass slide along the direction of the target light coincides with the second hole.

[0036] The cover plate connects to the sample carrier plate to fix the glass slide and the sample to be tested.

[0037] In one embodiment, the temperature displacement control module includes:

[0038] Temperature controller, used to set a preset temperature range;

[0039] A mechanical pump is connected to the sample chamber via a first pipe and is used to evacuate the sample chamber.

[0040] Thermostat, which is in contact with the sample chamber;

[0041] The liquid nitrogen tank contacts the sample chamber through a second pipe built into a thermostat to provide a cooling source for the sample chamber.

[0042] The thermostat is also connected to a temperature controller. The thermostat is used to adjust the flow rate of liquid nitrogen in the second pipe according to a preset temperature range so that the temperature in the sample chamber is maintained within the preset temperature range.

[0043] In one embodiment, the temperature displacement control module further includes:

[0044] Three-axis mechanical displacement platform;

[0045] The snap-fit ​​structure is used to fix the thermostat to the triaxial mechanical displacement platform, so that the position of the sample chamber can be adjusted based on the triaxial mechanical displacement platform, so that the microscopic imaging module can project the received target light onto the micro-area of ​​the sample to be tested in the sample chamber.

[0046] The aforementioned transient absorption spectroscopy detection system's microscopic imaging module can compress the spot size of the target light emitted from the output light module to the micrometer scale; the temperature displacement control module can provide the temperature environment required by the user and can also be moved to the sample chamber to ensure that the spot of the target light can cover the micro-area to be measured. Thus, based on the collaborative work of the output light module, microscopic imaging module, temperature displacement control module, and spectrometer, the detection dimensions of transient absorption spectroscopy technology are expanded, enabling in-situ study of the evolution of non-equilibrium dynamics of materials with temperature at the micro-nano scale. In particular, it provides a reliable detection system for non-contact, non-destructive detection of charge density wave phase transitions in two-dimensional materials, and provides key experimental data support across scales and multiple parameters for the design and optimization of two-dimensional materials and quantum devices. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is one of the structural block diagrams of a transient absorption spectroscopy detection system according to an embodiment;

[0049] Figure 2 This is a second structural block diagram of a transient absorption spectroscopy detection system according to one embodiment;

[0050] Figure 3This is a partial structural diagram of a transient absorption spectroscopy detection system according to one embodiment;

[0051] Figure 4 The image shows the detection results of a two-dimensional 1T-TiSe2 material at various temperatures using a transient absorption spectroscopy detection system, as an example of one embodiment. Detailed Implementation

[0052] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0054] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first microscope may be referred to as a second microscope, and similarly, a second microscope may be referred to as a first microscope. Both the first microscope and the second microscope are microscopes, but they are not the same microscope.

[0055] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0056] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0057] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0058] Traditionally, the detection of CDW phase transitions in materials relies primarily on contact measurement methods, which depend on scanning Kelvin probe force microscopy and / or conductive atomic force microscopy. While these methods offer nanometer-level resolution, the direct contact or extremely close proximity of the probe to the sample surface can lead to interference between the probe and the sample, potentially affecting the sensitive CDW phase. Furthermore, the AC or DC bias applied in these methods can alter the intrinsic electrical state of the material, thus impacting the accurate characterization of the phase transition behavior. Especially during temperature-varying measurements, differences in thermal expansion of the contact probe can further introduce measurement errors or cause sample surface damage.

[0059] In addition, although traditional transient absorption spectroscopy systems can compress the light spot to the micrometer level through the microscopic imaging module, thereby achieving precise positioning and dynamic analysis of the microstructure of two-dimensional material samples, the sample chamber of traditional transient absorption spectroscopy systems is a conventional sample chamber. This conventional sample chamber only supports room temperature testing and cannot meet the research needs of temperature-dependent phase transition behavior or low-temperature sensitive processes.

[0060] Furthermore, existing liquid nitrogen cryostats are bulky and have insufficient working distance from the objective lens. This insufficient working distance can cause spatial interference, leading to the failure of the microscopic imaging function. Moreover, mechanical drift during temperature changes can disrupt the alignment accuracy between the light spot and the target micro-region, making continuous observation of micro-region dynamics at low temperatures impossible.

[0061] In a specific embodiment, such as Figure 1 As shown, a transient absorption spectroscopy detection system 1 is provided, including: an output light module 10, a microscopic imaging module 20, a temperature displacement control module 30, and a spectrometer 40.

[0062] The output light module 10 is used to output target light, which is a beam of pump light and probe light combined with an optical path difference within a preset floating range.

[0063] The probe light can be supercontinuous white light with a wavelength in the range of 450nm to 1250nm.

[0064] To achieve the maximum optical path adjustment range in pump-probe experiments, the optical path lengths of the pump light and the probe light reaching the sample can be set to be approximately equal, meaning the optical path difference between the pump and probe lights approaches zero. Therefore, the preset floating range can be 0 to x, where x is a positive number.

[0065] The microscopic imaging module 20 is placed inside the spectral detection chamber. The microscopic imaging module 20 is used to receive the target light and project the target light onto the micro-area of ​​the sample to be tested. The optical path of the target light is collinear with the optical axis of the microscope group in the microscopic imaging module 20.

[0066] The temperature displacement control module 30 is used to maintain the temperature inside the sample chamber 50 within a preset temperature range; and to control the position of the sample chamber 50 so that the microscopic imaging module 20 can project the received target light onto the micro-area of ​​the sample to be tested inside the sample chamber 50.

[0067] Specifically, the target light spot should at least cover the micro-region to be measured. However, if the area of ​​the target light spot projected onto the sample is much larger than the area of ​​the micro-region to be measured, the target light will excite sample molecules outside the micro-region to be measured, thus obscuring the spectral signal that actually needs to be detected. Therefore, preferably, the area of ​​the target light spot projected onto the sample is slightly larger than the area of ​​the micro-region to be measured.

[0068] The microscopic imaging module 20 is used to compress the spot size of the target light to the micrometer level, thereby achieving precise excitation and detection of the micro-area to be measured and avoiding interference of the non-micro-area to be measured on the spectral signal.

[0069] The temperature displacement control module 30 can provide a preset temperature environment for the sample to be tested, including a low temperature environment.

[0070] By adjusting the position of the sample chamber 50, the micro-area to be tested can be moved, so that the spot of the target light projected onto the sample can precisely cover the micro-area to be tested, ensuring that the target light can accurately excite the sample molecules in the micro-area to be tested.

[0071] The spectrometer 40 is used to acquire the spectral signal of the micro-region to be measured, and based on the spectral signal, to obtain the transient absorption spectrum of the micro-region to be measured within a preset temperature range.

[0072] The aforementioned transient absorption spectroscopy detection system 1, with its microscopic imaging module 20 capable of compressing the spot size of the target light emitted from the output light module 10 to the micrometer scale, and its temperature displacement control module 30 capable of providing the temperature environment required by the user and being moved to the sample chamber 50, ensures that the spot of the target light can cover the micro-area to be measured. Thus, based on the collaborative work of the output light module 10, the microscopic imaging module 20, the temperature displacement control module 30, and the spectrometer 40, the detection dimensions of transient absorption spectroscopy technology are expanded. This allows for in-situ study of the evolution of non-equilibrium dynamics of materials with temperature at the micro-nano scale. In particular, it provides a reliable detection system for non-contact and non-destructive detection of charge density wave phase transitions in two-dimensional materials, and provides key experimental data support across scales and multiple parameters for the design and optimization of two-dimensional materials and quantum devices.

[0073] In a specific embodiment, such as Figure 2 As shown, the microscopic imaging module 20 includes: a photosensitive imaging module 202, a sampling cube 204, and a microscope group; the microscope group includes a first microscope 206 and a second microscope 208.

[0074] The sampling cube 204 is set in the optical path of the target light. The sampling cube 204 is used to couple the imaging path of the photosensitive imaging module 202 and the imaging path of the first microscope 206 to the optical path of the target light, so that the spot imaging of the target light and the micro-area imaging of the micro-area to be measured can be observed simultaneously in the photosensitive imaging module 202.

[0075] The first microscope 206 is positioned in the optical path of the target light emitted from the sampling cube 204. The first microscope 206 is used to magnify the micro-area to be measured and to focus the target light onto the micro-area to be measured.

[0076] The second microscope 208 is positioned in the optical path of the target light emitted from the first microscope 206 and is located between the sample to be tested and the spectrometer 40. The second microscope 208 is used to restore the light focused on the micro-area to be tested into parallel light and project it onto the spectrometer 40.

[0077] The first microscope 206 and the second microscope 208 are not in contact with the sample chamber 50; the optical axes of the first microscope 206 and the second microscope 208 are both collinear with the optical path of the target light.

[0078] The photosensitive imaging module 202 can observe the spot imaging of the target light and the micro-area imaging of the micro-area to be measured in real time, thereby accurately selecting the micro-area to be measured for spectral detection and adjusting the spatial overlap between the target light and the micro-area to be measured. The photosensitive imaging module 202 can be a CCD (Charge-Coupled Device Camera).

[0079] When detecting charge density wave phase transitions in two-dimensional materials, a relatively thin micro-region needs to be selected to ensure that the probe light can pass through the sample. However, the micro-region cannot be too thin, otherwise too few sample molecules will be excited by the pump light, resulting in a weak spectral signal generated by the pump-probe experiment. Therefore, a reliable micro-region needs to be determined based on the specific state of the sample. Preferably, the spots of the pump and probe light should be as small as possible to completely cover the micro-region and minimize the non-sample area covered by the pump and probe light spots, thereby ensuring the purity of the spectral signal.

[0080] Preferably, the sampling cube 204 is a 90:10 non-polarized beam splitter cube. It should be noted that when it is necessary to observe the spot imaging of the target light and the micro-area imaging of the micro-area to be measured, the sampling cube 204 is installed in the optical path of the target light; when performing spectral detection, the sampling cube 204 is removed from the optical path of the target light.

[0081] The first microscope 206 can focus the target light to reduce the spot size, enabling it to precisely target the micro-area of ​​the sample. The first microscope 206 can have a magnification of 4x, while the second microscope 208 can have a magnification of 10x.

[0082] It should be noted that if the magnification of the first microscope 206 and the second microscope 208 is insufficient to support the spectral detection of the micro-area to be measured, a microscope head with a higher magnification needs to be used. However, replacing it with a microscope head with a higher magnification will shorten the focal length of the first microscope 206 and / or the second microscope 208, thus causing a mismatch with the size of the sample chamber 50. Specifically, the magnification of the first microscope 206 is not necessarily less than that of the second microscope 208; the combination of the first microscope 206 and the second microscope 208 can be adjusted according to the size of the micro-area to be measured. If the 4x magnification of the first microscope 206 and / or the 10x magnification of the second microscope 208 cannot meet the experimental detection requirements, a microscope with a higher magnification can be used.

[0083] It is important to note that the higher the magnification of the microscope, the smaller its focal length. An excessively small focal length can result in insufficient space between the first microscope 206 and the second microscope 208 to accommodate the sample chamber 50, thus preventing normal experimental execution. Therefore, the sample chamber 50 can be moved within a certain range to re-match the focal lengths of the first microscope 206 and the second microscope 208. However, if the focal length of the first microscope 206 or the second microscope 208 is smaller than the radius of the sample chamber 50, the lenses of the first microscope 206 and / or the second microscope 208 will already be in contact with the sample chamber 50 before the micro-area to be measured reaches the focal point of the first microscope 206 and / or the second microscope 208. In this case, it is necessary to replace the microscope with one of a larger focal length, or to replace the sample chamber 50 with one of a smaller size.

[0084] In a specific embodiment, such as Figure 2 As shown, the microscopic imaging module 20 also includes a bright-field module 210.

[0085] The bright field module 210 is used to provide illumination for micro-area imaging of the micro-area to be measured.

[0086] The sampling cube 204 is used to couple the imaging path of the photosensitive imaging module 202, the imaging path of the first microscope 206, and the optical path of the bright field module 210 to the optical path of the target light.

[0087] The bright-field module 210 has a built-in light source for providing illumination for micro-area imaging of the micro-area under test. The light source of the bright-field module 210 can be an LED (Light Emitting Diode) light source.

[0088] In a specific embodiment, such as Figure 2 As shown, the output light module 10 includes: a laser 101, a beam splitter 102, an optical parametric amplifier (OPA) 103, an optical path adjustment module 104, a first filter 105, a focusing convex lens 106, a nonlinear crystal 107, a band-stop filter 108, a parabolic mirror 109, a second filter 110, and a beam combiner 111.

[0089] Laser 101 is used to output pulsed laser; wherein, laser 101 is placed outside the spectral detection box.

[0090] Laser 101 can be a femtosecond laser, and the pulsed laser output by laser 101 can be a femtosecond pulsed laser with a center wavelength of 1030nm.

[0091] The laser 101 has complex internal components and occupies a large volume, comparable in size to the spectral detection box, making it impossible to place inside the spectral detection box. Therefore, the laser 101 can be regarded as an independent, parallel subsystem at the same level as the spectral detection system.

[0092] The beam splitter 102 is used to receive the pulsed laser light from the laser 101 and output a first seed light and a second seed light; wherein the first seed light is the seed light of the probe light and the second seed light is the seed light of the pump light.

[0093] Beam splitter 102 can reflect a portion of the pulsed laser light generated from laser 101 and introduce it into the spectral detection box, thereby exciting nonlinear crystal 107 to generate probe light. The probe light can be supercontinuum white light in the wavelength range of 450–1250 nm.

[0094] An optical parametric amplifier 103 is placed in the optical path of the second seed light. The optical parametric amplifier 103 is used to convert the second seed light into pump light within the target wavelength range.

[0095] The optical parametric amplifier 103 can convert a second seed light with a center wavelength of 1030nm into pump light in the 210-2600nm band based on the principle of nonlinear optics.

[0096] The optical path adjustment module 104 is set in the optical path of the first seed light, and the optical path adjustment module 104 is used to adjust the optical path of the first seed light.

[0097] The optical path of the first seed light can be adjusted by the optical path adjustment module 104, which can adjust the optical path difference between the pump light and the probe light.

[0098] The first filter 105 is disposed in the optical path of the pump light emitted from the optical parametric amplifier 103, and the first filter 105 is used to adjust the energy of the pump light.

[0099] The first filter 105 can be a circular gradient neutral density filter.

[0100] The operating wavelength range of the first filter 105 needs to cover the wavelength of the pump light, while the operating wavelength range of the neutral density filter is generally broadband. The energy of the pump light is related to the spectral signal in the pump-probe experiment. If the pump light intensity is weak, it cannot effectively excite the micro-region of the sample, resulting in a weak spectral signal. If the pump light intensity is too strong, it will cause the pump light signal to oversaturate, resulting in the spectral signal being submerged in the pump light signal, making it impossible to extract the true spectral signal.

[0101] A focusing convex lens 106 is disposed in the optical path of the first seed light emitted from the optical path adjustment module 104. The focusing convex lens 106 is used to focus the first seed light before it is emitted.

[0102] The nonlinear crystal 107 is disposed in the optical path of the first seed light emitted from the focusing convex lens 106. The nonlinear crystal 107 is used to convert the received light into a focused probe light.

[0103] The focusing convex lens 106 can focus the first seed light with a wavelength of 1030 nm onto the nonlinear crystal 107, thereby enabling the nonlinear crystal 107 to generate focused probe light. The nonlinear crystal 107 can be sapphire or calcium fluoride crystal. The wavelength range of the focused probe light is 450 nm to 1250 nm.

[0104] A band-stop filter 108 is placed in the optical path of the focused probe light emitted from the nonlinear crystal 107.

[0105] The band-stop filter 108 can remove light with a wavelength of 1030 nm emitted from the nonlinear crystal 107, thereby preventing light outside the target wavelength range from affecting subsequent spectral detection results.

[0106] The parabolic mirror 109 is disposed in the optical path of the focused probe light emitted from the band filter 108. The parabolic mirror 109 is used to restore the focused probe light into a parallel probe light; wherein, the parallel probe light is the probe light in the target light.

[0107] The parabolic mirror 109 can be an off-axis parabolic mirror 109 collimated at 90°, and the effective focal length of the parabolic mirror 109 can be 50.8mm.

[0108] The second filter 110 is placed in the optical path of the probe light emitted from the parabolic mirror 109, and the second filter 110 is used to adjust the energy of the probe light.

[0109] The second filter 110 can be a circular gradient neutral density filter.

[0110] The second filter 110 needs to cover the wavelength of the probe light within its operating wavelength range; neutral density filters typically have a broadband operating wavelength range. Similar to the pump light, the energy of the probe light is also related to the spectral signal of the pump-probe experiment, where the probe light energy can be stronger than the pump light energy. However, excessively strong probe light energy can cause thermal effects on the surface of the sample, thus affecting the spectral signal results of the pump-probe experiment.

[0111] The beam combiner 111 is disposed in the optical path of the pump light emitted from the first filter 105 and the optical path of the probe light emitted from the second filter 110. The beam combiner 111 is used to overlap the optical paths of the pump light and the probe light.

[0112] The beam combiner 111 can be a dichroic mirror. The pump light can be reflected by the beam combiner 111, and the probe light can pass through it. Therefore, the optical paths of the pump light and the probe light can be overlapped. Generally, the wavelength of the pump light is shorter than that of the probe light. However, when a longer wavelength pump light is required in a pump-probe experiment, a neutral density filter with an OD (Optical Density) of 0.3 can be used instead of the dichroic mirror. This allows the requirements of the pump-probe experiment to be met by sacrificing some of the energy of the pump and probe light.

[0113] In one embodiment, the optical path adjustment module 104 includes a plurality of reflectors 112 and a displacement control platform.

[0114] The displacement control platform can be a high-precision electrically controlled displacement platform. Multiple reflectors 112 can change the optical path direction of the first seed light through light reflection. The displacement control platform can adjust the distance between each reflector 112, thereby adjusting the optical path of the first seed light.

[0115] For example, the reflector 112 in the optical path adjustment module 104 can also be replaced by a hollow retroreflector. Furthermore, if it is necessary to increase the adjustable optical path range, the number of retroreflections of the first seed light can be increased by increasing the number of hollow retroreflectors.

[0116] In one embodiment, such as Figure 2 As shown, the emitted light module 10 also includes multiple reflectors 112.

[0117] The mirrors 112 positioned in the optical path of the first seed light and before the incident direction of the focusing convex lens 106, namely mirrors 112(a), 112(b), 112(d), 112(e), 112(f), 112(g), and 112(m), can be high-reflectivity mirrors with a wavelength of 1030 nm. The mirrors 112 positioned in the optical path of the first seed light and after the exit direction of the second filter 110, namely mirror 112(n), can be broadband high-reflectivity mirrors. The mirrors 112 positioned in the optical path of the second seed light and after the exit direction of the optical parametric amplifier 103, namely mirrors 112(c), 112(h), 112(i), 112(j), 112(k), and 112(l), can be broadband high-reflectivity mirrors. If the wavelength of the pump light in the pump-probe experiment exceeds the effective reflection range of the installed broadband high-reflectivity mirror, a broadband high-reflectivity mirror with a suitable wavelength needs to be replaced to ensure that the energy of the pump light in the pump-probe experiment is above the required energy. Therefore, the purpose of the multiple reflectors 112 is at least to project the pump light onto the beam combiner 111 and to compensate for the increased optical path length caused by the optical path adjustment module 104 installed on the optical path of the first seed light. Therefore, the number of reflectors 112 in the output light module 10 cannot be arbitrarily increased or decreased; the optical path length of the pump light must be reasonably compensated according to the specific value of the optical path length of the probe light. Thus, after carefully adjusting the reflectors 112(n) and the beam combiner 111, the optical paths of the pump light and the probe light can be made to coincide after passing through the beam combiner 111.

[0118] It should be noted that the principle of the pump-probe experiment is based on controlling the time delay between the laser pulse and the micro-region under test by adjusting the optical path difference between the pump light and the probe light. By acquiring spectral signals under different time delays, time-resolved spectral information can be obtained. Therefore, the optical path difference between the pump light and the probe light can be controlled by an optical path adjustment module 104. In ultrafast spectroscopy experiments, the optical path of the pump light is usually fixed while the optical path of the probe light is adjusted. Therefore, the optical path adjustment module 104 can be set in the optical path of the probe light, i.e., the optical path of the first seed light, without the need to add an optical path adjustment module 104 to the optical path of the pump light or the optical path of the second seed light. The wavelength of the pump light is determined by the optical parametric amplifier 103, which outputs pump light of a preset wavelength. The wavelength of the pump light is determined by the specific sample under test and the detection requirements.

[0119] Among them, reflectors 112(a), 112(b) and 112(c) can all be placed outside the spectral detection chamber.

[0120] In one embodiment, such as Figure 2As shown, the optical path adjustment module 104 includes two reflectors 112 and a high-precision electrically controlled displacement platform. The optical path adjustment module 104 is housed within the spectral detection chamber.

[0121] Specifically, the high-precision electrically controlled displacement platform consists of an uppermost displacement platform, a middle high-precision electrically controlled threaded rod, and a base. The base of the high-precision electrically controlled displacement platform is fixed inside the spectral detection box. The two reflectors 112 in the optical path adjustment module 104 are fixed on the uppermost displacement platform. The uppermost displacement platform is controlled by a remote terminal and can move back and forth on the high-precision threaded rod with micron precision to increase or decrease the optical path between reflectors 112(d) and 112(e), as well as between reflectors 112(g) and 112(f).

[0122] Furthermore, in the absence of a high-precision electrically controlled displacement platform in the optical path adjustment module 104, the number of reflectors 112 can be increased or decreased by moving the positions of reflectors 112(e) and 112(f), thereby achieving optical path adjustment. However, this method cannot guarantee the temporal resolution of transient absorption spectroscopy detection, nor can it efficiently acquire time-resolved spectral data. This is because the displacement accuracy of the high-precision electrically controlled displacement platform is a key parameter determining the temporal resolution of spectral detection. That is, by precisely changing the optical path difference between the pump light and the probe light, the time delay between the pump light and the probe light can be precisely controlled, thereby enabling transient absorption spectroscopy detection to have high temporal resolution and detect short-lived ultrafast dynamic processes in the sample.

[0123] In a specific embodiment, such as Figure 2 As shown, the transient absorption spectroscopy detection system 1 also includes a control terminal 60.

[0124] The control terminal 60 is connected to the optical path adjustment module 104. The control terminal 60 acquires and drives the optical path adjustment module 104 according to the adjustment command, so that the optical path adjustment module 104 adjusts the optical path of the first seed light. The adjustment command can be an adjustment command issued by the operator or an adjustment command pre-configured in the control terminal.

[0125] The control terminal 60 is connected to the optical path adjustment module 104, thereby setting relevant parameters such as the distance of each movement, the total number of steps, the time interval between each step, and the total number of cycles in the optical path adjustment module 104 based on the control terminal 60. Specifically, the control terminal 60 controls the reflector 112 mounted on the displacement control platform in the optical path adjustment module 104 to achieve the purpose of adjusting the optical path.

[0126] Furthermore, the control terminal 60 can also be connected to the spectrometer 40 to perform spectral signal acquisition linkage based on the spectrometer 40 and the optical path adjustment module 104, thereby completing the acquisition of time-resolved spectra.

[0127] In one embodiment, the control terminal 60 is also connected to the laser 101, the optical parametric amplifier 103, the photosensitive imaging module 202, and the bright field module 210, respectively, to control the start-up, shutdown, and parameter settings of the laser 101, the optical parametric amplifier 103, the photosensitive imaging module 202, and the bright field module 210 based on the instructions issued by the control terminal 60.

[0128] In one specific embodiment, in the beam splitter 102, the splitting ratio of the first seed light is smaller than that of the second seed light.

[0129] The beam splitting ratio of the beam splitter 102 is determined based on the difference in seed light energy required to prepare the pump light and the probe light. When the first seed light directly excites the nonlinear crystal 107, the probe light can be obtained directly. However, the preparation of the pump light requires a complex optical parametric amplifier 103. This optical parametric amplifier 103 can be considered as an independent, parallel subsystem at the same level as the laser 101 and the spectral detection system. After the second seed light is input into the optical parametric amplifier 103, it suffers significant energy loss during the process of being prepared into the pump light of the wavelength required for experimental detection. Therefore, the beam splitting ratio of the second seed light needs to be greater than that of the first seed light. For example, the beam splitting ratio of the first and second seed lights can be 1:9, that is, 10% of the pulsed laser light generated by the laser 101 is used to prepare the probe light, and 90% of the pulsed laser light generated by the laser 101 is used to prepare the pump light.

[0130] In a specific embodiment, such as Figure 2 As shown, the target sidewall of the sample chamber 50 is a transparent window, and the two transparent windows arranged opposite each other are made of the same material; wherein, the target sidewall is the sidewall located in the optical path of the target light.

[0131] The sample to be tested is placed between the sample carrier 502 and the glass slide in the sample chamber 50. The sample carrier 502 has a first hole and the glass slide has a second hole. The projection of the first hole on the glass slide along the direction of the target light coincides with the second hole. The projection of the micro-area to be tested on the glass slide along the direction of the target light is located in the second hole.

[0132] Specifically, the sample chamber 50 can be a cuboid with a square base. Each of the four sides of the sample chamber 50 is fitted with a transparent window made of two different materials, including quartz and calcium fluoride. During the pump-probe experiment, the material of the window in the optical path of the target light must be selected based on the material of the glass slide. Alternatively, all four side walls of the sample chamber 50 can be transparent windows, allowing the operator to directly observe the sample inside the sample chamber 50 through these windows.

[0133] The transparent window ensures that the microscopic imaging module 20 can directly observe the sample under test through the transparent window, and also allows the target light to pass through the transparent window and be focused on the micro-area under test when detecting the transient absorption spectrum of the sample under test.

[0134] Furthermore, since a certain background spectral signal is generated when the target light passes through the window and the glass slide in sequence, if the material of the glass slide and the window are the same, the background spectral signal generated when the target light passes through the window and the glass slide in sequence is the same. This reduces the difficulty of distinguishing between the background spectral signal and the spectral signal, and can also quickly remove these background spectral signals, thereby ensuring the purity of the spectral signal.

[0135] In one specific embodiment, the sample chamber 50 also includes a cover plate.

[0136] The cover plate, the glass slide, and the sample 502 are stacked in sequence. The cover plate has a third hole. The projection of the third hole onto the glass slide along the direction of the target light coincides with the second hole. The cover plate is a metal cover plate.

[0137] The cover plate is connected to the sample carrier plate 502 to fix the glass slide and the sample to be tested.

[0138] Specifically, the cover plate can be connected to the sample carrier 502 via multiple fixing structures. For example, a glass slide with the sample attached is held down at its four corners by a cover plate with the same hollow area, and secured to the sample carrier 502 by multiple screws, each located at one of the four corners of the cover plate. It is important to note that when fixing the glass slide with the sample attached to the sample carrier 502, the side with the sample attached must face the sample carrier 502, while the cover plate secures the sample slide by pressing down on the side of the glass slide without the sample attached. Simultaneously, when placing the sample chamber 50 into the spectral detection chamber, it must be ensured that the side of the glass slide with the sample attached faces both the pump light and the probe light.

[0139] In a specific embodiment, such as Figure 2 and Figure 3 As shown, the temperature displacement control module 30 includes: a thermostat 301, a mechanical pump 302, a liquid nitrogen tank 303, and a temperature controller 304.

[0140] The temperature controller 304 is used to set a preset temperature range.

[0141] Mechanical pump 302 is connected to sample chamber 50 through the first pipe, and mechanical pump 302 is used to evacuate sample chamber 50.

[0142] The thermostat 301 is in contact with the sample chamber 50. Specifically, the thermostat 301 can be connected to one side wall of the sample chamber 50, and the connection between the thermostat 301 and the sample chamber 50 is coated with vacuum grease. The application of vacuum grease at the connection between the thermostat 301 and the sample chamber 50 allows a low vacuum to be maintained within the sample chamber 50 during pump-probe experiments. The pressure within the sample chamber 50 can be in the range of 10⁻⁴ to 10⁻⁵ Pa.

[0143] The liquid nitrogen tank 303 contacts the sample chamber 50 through a second pipe built into the thermostat 301 to provide a cooling source for the sample chamber 50.

[0144] The thermostat 301 is also connected to the temperature controller 304. The thermostat 301 is used to adjust the flow rate of liquid nitrogen in the second pipe according to the preset temperature range so that the temperature in the sample chamber 50 is maintained within the preset temperature range.

[0145] The cryostat 301 can be a continuous-flow cryostat 301, which can be set within a wide temperature range of 77~800K and maintain temperature stability of ±0.001K, effectively suppressing thermal disturbances at room temperature and enabling transient absorption spectroscopy detection of cryogenically sensitive processes (such as charge density wave phase transitions and electron-phonon coupling). Specifically, the cryostat 301 can be connected to a mechanical pump 302, a liquid nitrogen tank 303, and a temperature controller 304. Before cooling the sample chamber 50, it needs to be evacuated. Therefore, the mechanical pump 302 can be started first, and after the pressure inside the sample chamber 50 drops to the level of 10⁻³~10⁻⁴ Pa, the valve of the liquid nitrogen tank 303 can be opened. The cryostat 301 can achieve intelligent control based on a preset temperature range, thereby controlling the liquid nitrogen flow rate to reasonably adjust the temperature inside the sample chamber 50 to achieve the state required for the pump-detection experiment.

[0146] It should be noted that the vacuuming described above refers to evacuating the sample chamber 50, not the entire spectral detection chamber. The sample chamber 50 is an independent, insulated vacuum chamber. While thermal convection exists around it, this convection does not affect the sample inside. Part of the sample chamber 50 can be enclosed by the thermostat 301, allowing the thermostat 301 to cool the portion of the sample chamber 50 it contacts by adjusting the flow rate of liquid nitrogen. In other words, the liquid nitrogen in the liquid nitrogen tank 303 flows through the second pipe to the side wall of the sample chamber 50 enclosed by the thermostat 301, cooling it by contact with its outer wall, rather than flowing into the interior of the sample chamber 50.

[0147] Furthermore, the temperature control of the sample chamber 50 can be achieved through contact between the second pipe inside the thermostat 301 and the heating wire. Simultaneously, the mechanical pump 302 needs to continuously operate to maintain the vacuum level within the sample chamber 50, thereby maintaining a stable low-temperature environment. The heating wire can be wound around the portion of the sample chamber 50 encased in the thermostat 301. A temperature probe can be installed inside the sample chamber 50, and the temperature controller 304 can adjust the start / stop and power of the heating wire based on the real-time temperature data transmitted from the probe, and can also regulate the flow rate of liquid nitrogen.

[0148] Integrating the first and second pipes within the thermostat 301 significantly reduces the complexity of the external mechanical structure. The thermostat 301 can be cylindrical.

[0149] In a specific embodiment, such as Figure 2 and Figure 3 As shown, the temperature displacement control module 30 also includes a three-axis mechanical displacement platform 305 and a snap-fit ​​structure 306.

[0150] The snap-fit ​​structure 306 is used to fix the thermostat 301 onto the triaxial mechanical displacement platform 305, so as to adjust the position of the sample chamber 50 based on the triaxial mechanical displacement platform 305, so that the microscopic imaging module 20 projects the received target light onto the micro-area of ​​the sample to be tested within the sample chamber 50. The sample chamber 50 is tightly fixed to the triaxial mechanical displacement platform 305, and the snap-fit ​​structure 306 is fixedly connected to the thermostat 301. The snap-fit ​​structure 306 can be a ring-shaped metal snap-fit.

[0151] The three-axis mechanical displacement platform 305 includes an X-axis mechanical displacement platform 3052, a Y-axis mechanical displacement platform 3054, and a Z-axis mechanical displacement platform 3056. Therefore, based on the three-axis mechanical displacement platform 305, three-dimensional adjustment in XYZ axes can be achieved with an adjustment accuracy of 0.01 mm. The three-axis mechanical displacement platform 305 is used to precisely adjust the position of the micro-area under test in the spectral detection chamber to coincide with the spot of the target light, and to adjust the distance between the micro-area under test and the microscope, so that the micro-area under test is at the focal point of the first microscope 206 and the focal point of the second microscope 208.

[0152] In one embodiment, the temperature displacement control module 30 further includes a perforated storage platform 307.

[0153] The perforated storage platform 307 is used to place the three-axis mechanical displacement platform 305.

[0154] Specifically, the height of the perforated platform 307 can be determined according to the volume of the spectral detection box. After installing the triaxial mechanical displacement platform 305 and the thermostat 301, the perforated platform 307 can ensure that the position of the sample chamber 50 is exactly in the optical path of the target light, and meet the requirement that the position of the micro-area to be measured can be accurately adjusted within the adjustable range of the triaxial mechanical displacement platform 305.

[0155] The temperature displacement control module 30 is L-shaped, with the sample chamber 50 containing the sample to be tested located at one end of the L. The other end contains a liquid nitrogen chamber and a heating wire. Liquid nitrogen can be poured in for cooling operations, and the heating wire needs to be energized for heating operations. The temperature controller 304 can monitor the temperature inside the sample chamber 50 in real time and reasonably control the flow rate of liquid nitrogen and the power of the heating wire according to the preset temperature range, so that the temperature inside the sample chamber 50 can be maintained stably for a long time.

[0156] The sample chamber 50 can be placed vertically downwards. The three-dimensional spatial position of the sample chamber 50 can be controlled by the triaxial mechanical displacement platform 305, thereby adjusting the position of the micro-area under test in the optical path of the target light, ensuring that the micro-area under test is precisely at the focal point of the target light. The sample chamber 50 is connected to a mechanical pump 302, which evacuates the sample chamber 50 to a rough vacuum state. The vacuum state of the sample chamber 50 helps maintain a stable temperature inside the sample chamber 50 and also prevents water molecules in the air from condensing on the transparent window or the sample under test after the temperature inside the sample chamber 50 is lowered, thus improving the experimental results of detecting transient absorption spectra.

[0157] The transient absorption spectroscopy detection system 1 proposed in this application can adopt a non-contact in-situ detection method. The transient absorption spectroscopy detection system 1 is based on transient absorption spectroscopy technology. Its core advantage is that it completely avoids many problems caused by physical contact and determines the occurrence of CDW phase transition by accurately measuring the coherent phonon lifetime of the material at different temperatures.

[0158] Specifically, transient absorption spectroscopy is an ultrafast time-resolved technique based on the pump-probe principle. It primarily achieves qualitative and quantitative analysis of a sample by measuring the transient change in its absorption coefficient after photoexcitation. Its core principle is to quantify the difference between the excited and ground states through differential absorption spectroscopy, thereby resolving processes such as excited-state relaxation, carrier dynamics, and photochemical reaction transition states. This technology is widely used in fields such as optoelectronic material and device optimization, photocatalysis and energy material characterization, low-dimensional material quantum behavior detection, biophotochemistry and medicine, and environmental and chemical kinetics. The core system of the transient absorption spectrometer 40 includes: a light source system, a time control system, a detection and spectral analysis system, and a sample chamber and signal processing system. The workflow is as follows: after the pump light excites the sample to a non-equilibrium state, the probe light penetrates the sample within a controllable delay time. The spectrometer 40 records the differential absorption signal, and by analyzing the signal symbol and spatiotemporal evolution, combined with global fitting, parameters such as carrier lifetime and reaction rate are extracted.

[0159] Currently, transient absorption spectroscopy has been successfully applied to the ultrafast dynamic characterization of solid and liquid samples. Based on the femtosecond laser pump-probe principle, it can resolve processes such as excited-state relaxation and carrier recombination. When measuring solid samples in the micro-regions to be measured, the transient absorption spectroscopy detection system 1 integrates a microscopic imaging module 20 in the sample chamber 50. This allows the pump and probe light spots to be compressed to the micrometer scale using a high numerical aperture objective lens, breaking through the limitations of millimeter-scale spots in traditional transient absorption spectroscopy. This enables precise positioning and dynamic analysis of micro-region heterostructures such as two-dimensional materials, heterojunction structures, and perovskite quantum dot arrays, avoiding spatial ambiguity of the signal. Furthermore, in conjunction with a high-speed CCD camera, real-time observation and positioning of the measured region can be achieved, ensuring that the light spot can accurately act on the measured micro-region of the sample. Combined with the bright-field illumination module and the real-time observation function of the CCD camera, it can also support the visualization of the morphology of the measured micro-region. This transient absorption spectroscopy detection system significantly improves the spatial resolution of transient absorption spectroscopy in the study of solid-state heterogeneous materials, effectively solving the problem of detecting the dynamics of micro-regions in low-dimensional materials, and can accurately resolve the carrier relaxation paths at grain boundaries or interfaces. Furthermore, when the research object involves temperature-sensitive phase transition behavior or requires suppression of thermal noise under low-temperature conditions, the optical path structure of the ultrafast microscopy imaging system and a compatible low-temperature isothermal sample chamber 50 are used to ensure that the sample under test remains in a set low-temperature environment throughout the entire detection process, effectively isolating external temperature fluctuations and mechanical vibration interference, thereby ensuring the stability of measurement conditions and the reliability of data.

[0160] To better understand the operation process of the transient absorption spectroscopy detection system 1 described above, an operating method is first provided:

[0161] Turn on the femtosecond laser 101 and the optical parametric amplifier 103, and set the wavelength of the pump light required for the pump-probe experiment.

[0162] Start the mechanical pump 302 to evacuate the sample chamber 50, reducing the pressure inside the sample chamber 50 to the order of 10⁻³ to 10⁻⁴ Pa.

[0163] After the pressure in sample chamber 50 reaches the required level of 10⁻³ to 10⁻⁴ Pa, open liquid nitrogen tank 303 and set temperature controller 304 to the preset temperature range required for the pump-probe experiment.

[0164] Once the temperature within the sample chamber 50 reaches the preset temperature range, the system continues to wait for a preset duration. The duration of temperature change within the sample chamber 50 is related to the preset temperature range; a smaller upper limit results in a longer cooling time, and a larger lower limit results in a longer heating time. When the upper or lower limit of the preset temperature range is just reached, the temperatures of the components within the temperature displacement control module 30 are not yet balanced. Therefore, the system continues to wait for the preset duration to allow the temperature to stabilize. Only after all components in the temperature displacement control module 30 have essentially reached thermal equilibrium, meaning they no longer expand or contract due to temperature differences, can the microscopic transient absorption spectroscopy detection begin.

[0165] Install sampling cube 204 and enable bright field module 210.

[0166] The positions of the pump light spot and the probe light spot are observed using a CCD camera. By adjusting the reflector 112(n) and the beam combiner 111, the pump light spot and the probe light spot are made to highly coincide.

[0167] Continue to observe the sample under test using a CCD camera, and select the micro-area to be tested so that the micro-area to be tested is highly coincident with the spot of the target light.

[0168] After the micro-area to be measured is selected, the three-dimensional spatial position of the thermostat 301 is fixed by the locking knob on the three-axis mechanical displacement platform 305 to prevent it from drifting.

[0169] Initiate spectral detection. The pump light excites the micro-region of the sample to be tested. By adjusting the time delay between the probe light and the pump light, the spectrometer 40 can obtain and record the change of the probe light over time, thereby obtaining the time-resolved transient absorption spectrum of the micro-region sample under low-temperature conditions.

[0170] Therefore, the aforementioned transient absorption spectroscopy detection system 1 can achieve continuous and precise temperature control from liquid nitrogen to room temperature while ensuring spatial resolution at the micrometer scale. The triaxial mechanical displacement platform 305 used can suppress mechanical drift and control it within the range of ≤1μm, overcoming the problem of positioning failure of the micro-area under test caused by thermal expansion of traditional thermostats. It also solves the problem of low compatibility and integration among the transient absorption spectroscopy module (including the output light module 10 and spectrometer 40), the microscopic imaging module 20, and the temperature displacement control module 30. Thus, it can realize the intrinsic law of the evolution of non-equilibrium dynamics with temperature at the micro-nano scale, providing a cross-scale, multi-parameter non-contact in-situ detection tool for the study of low-temperature ultrafast processes of two-dimensional materials and quantum devices.

[0171] Furthermore, one end of the thermostat 301 is connected to the sample chamber 50, and the sample chamber 50 is embedded between the first microscope 206 and the second microscope 208, which can shorten the working distance to 1mm, solve the problem of conflict between the traditional thermostat and the working distance of the microscope due to its large size, and achieve deep compatibility between low temperature environment and microscopic imaging, thereby supporting real-time temperature-kinetic correlation analysis and cross-scale in-situ detection.

[0172] For example, the transient absorption spectroscopy detection system 1 described above was used to perform temperature-varying transient absorption spectroscopy detection on two-dimensional 1T (trigonal)-TiSe2 (titanium diselenide) material at a scale of 10 μm. The preset temperature range was 80 K to 320 K, and the results were as follows: Figure 4 The test results are shown. In 1T, 1 indicates that the unit cell contains one layer of transition metal atoms; T indicates that the structure is triangular symmetric.

[0173] Specifically, in this variable-temperature transient absorption spectroscopy detection, light with a wavelength of 800 nm was used as the pump light, and femtosecond time-resolved transient absorption spectra were measured under temperature conditions of 80 K, 120 K, 160 K, 200 K, 240 K, 280 K and 320 K respectively. Figure 4 (a) shows the spectra at various temperatures under probe light with a wavelength of 540 nm. Figure 4 (b) in the figure represents the fitting residuals at various temperatures after global fitting. This was observed... Figure 4 It can be seen that the spectrum and the fitting residual change with temperature, and at temperatures of 240K and above, the fitting residual obviously exhibits an oscillation with a period of about 20ps. In other words, the two-dimensional 1T-TiSe2 material undergoes a laser-induced phase transition process at low temperatures.

[0174] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0175] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0176] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A transient absorption spectroscopy detection system, characterized by, include: The output light module is used to output target light, which is a beam of light obtained by combining pump light and probe light with an optical path difference within a preset floating range; A microscopic imaging module is placed inside a spectral detection chamber. The microscopic imaging module is used to receive the target light, and the optical path of the target light is collinear with the optical axis of the microscope group in the microscopic imaging module. A temperature displacement control module is used to maintain the temperature inside the sample chamber within a preset temperature range and to control the position of the sample chamber so that the microscopic imaging module projects the received target light onto the micro-area of ​​the sample to be tested inside the sample chamber. A spectrometer is used to acquire the spectral signal of the micro-region to be measured, and based on the spectral signal, to obtain the transient absorption spectrum of the micro-region to be measured within the preset temperature range.

2. The transient absorption spectroscopy detection system of claim 1, wherein, The microscopic imaging module includes: a photosensitive imaging module, a sampling cube, and the microscope group; the microscope group includes a first microscope and a second microscope. The sampling cube is disposed in the optical path of the target light. The sampling cube is used to couple the imaging path of the photosensitive imaging module and the imaging path of the first microscope to the optical path of the target light, so that the spot imaging of the target light and the micro-area imaging of the micro-area to be measured can be observed simultaneously in the photosensitive imaging module. The first microscope is positioned in the optical path of the target light emitted from the sampling cube. The first microscope is used to magnify the micro-area to be measured and to focus the target light onto the micro-area to be measured. The second microscope is positioned in the optical path of the target light emitted from the first microscope and is located between the sample to be tested and the spectrometer. The second microscope is used to convert the light focused on the micro-area to be tested into parallel light and project it onto the spectrometer. The first microscope and the second microscope are not in contact with the sample chamber; the optical axes of the first microscope and the second microscope are collinear with the optical path of the target light.

3. The transient absorption spectroscopy detection system of claim 2, wherein, The microscopic imaging module also includes: A bright-field module, which is used to provide illumination for micro-area imaging of the micro-area to be measured; The sampling cube is used to couple the imaging path of the photosensitive imaging module, the imaging path of the first microscope, and the optical path of the bright field module to the optical path of the target light.

4. The transient absorption spectroscopy detection system of claim 1, wherein, The emitted light module includes: A laser for outputting pulsed laser light; wherein the laser is placed outside the spectral detection chamber; A beam splitter is used to receive pulsed laser light from the laser and output a first seed light and a second seed light; wherein the first seed light is the seed light of the probe light and the second seed light is the seed light of the pump light. An optical parametric amplifier is placed in the optical path of the second seed light and is used to convert the second seed light into pump light within the target wavelength range. An optical path adjustment module is disposed in the optical path of the first seed light, and the optical path adjustment module is used to adjust the optical path of the first seed light. A first filter is disposed in the optical path of the pump light emitted from the optical parametric amplifier, and the first filter is used to adjust the energy of the pump light. A focusing convex lens is disposed in the optical path of the first seed light emitted from the optical path adjustment module, and the focusing convex lens is used to focus the first seed light before emission. A nonlinear crystal is disposed in the optical path of the light emitted from the focusing convex lens, and the nonlinear crystal is used to convert the received light into focused probe light. A band-stop filter is disposed in the optical path from which the focused probe light is emitted by the nonlinear crystal; A parabolic mirror is disposed in the optical path from which the focused probe light is emitted from the band-blocking filter. The parabolic mirror is used to restore the focused probe light into a parallel probe light; wherein, the parallel probe light is the probe light in the target light. A second filter is disposed in the optical path of the probe light emitted from the parabolic mirror, and the second filter is used to adjust the energy of the probe light; A beam combiner is disposed in the optical path from the first filter to emit the pump light and in the optical path from the second filter to emit the probe light. The beam combiner is used to coincide the optical paths of the pump light and the probe light.

5. The transient absorption spectroscopy detection system of claim 4, wherein, Also includes: Control terminal, the control terminal being connected to the optical path adjustment module; The control terminal is used to acquire and drive the optical path adjustment module according to the control command, so that the optical path adjustment module adjusts the optical path of the first seed light.

6. The transient absorption spectroscopy detection system of claim 4, wherein, In the beam splitter, the splitting ratio of the first seed light is smaller than that of the second seed light.

7. The transient absorption spectroscopy detection system of claim 1, wherein, The target sidewall of the sample chamber is a transparent window, and the two transparent windows arranged opposite each other are made of the same material; wherein, the target sidewall is the sidewall located in the optical path of the target light; The sample to be tested is placed between a sample slide and a glass slide in the sample chamber. The sample slide has a first hole, and the glass slide has a second hole. The projection of the first hole onto the glass slide along the projection direction of the target light coincides with the second hole. The projection of the micro-area to be tested onto the glass slide along the projection direction of the target light is located in the second hole.

8. The transient absorption spectroscopy detection system of claim 7, wherein, The sample chamber also includes a sample cover plate; The cover plate, the glass slide, and the sample plate are stacked in sequence. The cover plate has a third hole. The projection of the third hole onto the glass slide along the projection direction of the target light coincides with the second hole. The cover plate is connected to the sample carrier to fix the glass slide and the sample to be tested.

9. The transient absorption spectroscopy detection system according to claim 1, characterized in that, The temperature displacement control module includes: Temperature controller, used to set the preset temperature range; A mechanical pump, which is connected to the sample chamber via a first pipe, is used to evacuate the sample chamber. A thermostat, which is in contact with the sample chamber; A liquid nitrogen tank, which contacts the sample chamber through a second pipe built into the thermostat, to provide a cooling source for the sample chamber; The thermostat is also connected to the temperature controller. The thermostat is used to adjust the liquid nitrogen flow rate in the second pipe according to the preset temperature range so that the temperature in the sample chamber is maintained within the preset temperature range.

10. The transient absorption spectroscopy detection system according to claim 9, characterized in that, The temperature displacement control module also includes: Three-axis mechanical displacement platform; A snap-fit ​​structure is provided to fix the thermostat to the triaxial mechanical displacement platform, so as to adjust the position of the sample chamber based on the triaxial mechanical displacement platform, so that the microscopic imaging module can project the received target light onto the micro-area of ​​the sample to be tested in the sample chamber.

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