Switchable high harmonic xuv spectral probing system

Abstract

The application provides a switchable high-harmonic XUV spectrum detection system and relates to the field of laser measurement. The switchable high-harmonic XUV spectrum detection system comprises a femtosecond laser light source, a high-harmonic generation system and a spectrum detection system arranged in sequence. The spectrum detection system comprises: 1) a displacement mechanism and a first flat-field grating arranged on the displacement mechanism, wherein the displacement mechanism is used for moving the first flat-field grating to contact XUV; when the XUV contacts the first flat-field grating, a first light path is formed by diffraction, and vice versa, a second light path is formed; 2) a microchannel plate arranged in the first light path and a second tire mirror, a reflector, a second flat-field grating and a CCD camera arranged in sequence in the second light path. The detection mode of the application is switchable: the device adopts a mechanical full-optical measurement mode switching structure to realize rapid and stable switching of the detection mode.

Description

Technical Field

[0001] This invention relates to the field of laser measurement, and in particular to a switchable high-harmonic XUV spectral detection system. Background Technology

[0002] XUV spectroscopy has become an important experimental technique for probing ultrafast electronic dynamics processes in atomic, molecular, and condensed matter systems. By analyzing the modulation characteristics of transmission XUV spectra that vary with time delay, key information such as sub-femtosecond-scale dipole moment evolution, transient spectral reconstruction, photoinduced energy level shifts, and sub-periodic optical field-driven coupling can be obtained. This enables the observation and characterization of physical phenomena such as electron correlation-driven dynamics, self-ionization channels, Feynman resonance evolution, photoinduced states, Stark shifts, and coherent multi-electron processes.

[0003] However, existing XUV spectral characterization techniques still face significant bottlenecks. On the one hand, due to limitations in instrument structure and detector element performance, it is often difficult to balance detection range and detection accuracy: high-precision detection methods often result in a smaller detection range, while wide-range detection methods lead to relatively lower detection accuracy. On the other hand, XUV spectroscopy-based measurement systems are typically complex in structure and involve cumbersome adjustment procedures, requiring high levels of experimental operation and system stability, which in turn affects the repeatability and reliability of experimental results.

[0004] To address the aforementioned technical limitations, this invention proposes a switchable high-harmonic XUV spectral detection device, which offers the following key advantages: First, the device employs a mechanical, all-optical measurement mode switching structure, allowing for flexible selection of different spectral detection modes based on the energy level characteristics, spectral energy range, and experimental accuracy requirements of the gas sample, thus achieving rapid and stable switching between detection modes. Second, the device combines a microchannel plate detection system with a wide detection range with a CCD camera detection system with high detection accuracy, enabling switching detection of XUV spectra within the same energy range, thereby achieving XUV spectral measurements that balance wide range and high precision.

[0005] This technology has good universality for gas samples, and the XUV spectroscopy has a wide energy detection range, which can be applied to the detection of energy level evolution processes of most gas samples, providing a reliable technical means for the efficient characterization of various ultrafast electronic dynamic processes. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a switchable high-harmonic XUV spectral detection system that enables rapid and stable switching of detection modes.

[0007] This invention provides a switchable high-harmonic XUV spectral detection system, comprising: a femtosecond laser source, a high-harmonic generation system, and a spectral detection system arranged sequentially; the femtosecond laser source is used to emit femtosecond laser, and the high-harmonic generation system is used to convert the femtosecond laser into XUV; the spectral detection system includes: 1) a displacement mechanism and a first flat-focal-field grating disposed on the displacement mechanism, the displacement mechanism being used to move the first flat-focal-field grating to contact the XUV; when the XUV contacts the first flat-focal-field grating, diffraction forms a first optical path, otherwise it forms a second optical path; 2) a microchannel plate disposed in the first optical path and a second tire mirror, a reflector, a second flat-focal-field grating, and a CCD camera arranged sequentially in the second optical path.

[0008] In one feasible embodiment, the spectral detection system further includes: a femtosecond laser beam splitter, which is used to split the femtosecond laser beam into pump light and probe light; the high-order harmonic generation system includes: 1) a pump light reflector group and a first gas box sequentially disposed in the pump light path, the first gas box being used to convert the pump light into XUV; 2) an aperture, a first tire mirror, a hollow mirror, and a second gas box sequentially disposed in the XUV light path, the hollow mirror being located at the intersection of the pump light and the probe light; 3) a probe light reflector group and a probe light lens sequentially disposed in the probe light path.

[0009] In one feasible embodiment, the pump light reflector group includes: a first pump light reflector, a second pump light reflector, and a third pump light reflector arranged sequentially.

[0010] In one feasible embodiment, the first pump light reflector is a gold mirror, the second pump light reflector is a reflecting focusing mirror, and the third pump light reflector is a gold mirror.

[0011] In one feasible embodiment, the focal length of the second pump light reflector is 500 mm.

[0012] In one possible embodiment, the focal length of the probe lens is 400 mm; and / or, the focal length of the first tire mirror is 150 mm; and / or, the focal length of the second tire mirror is 100 mm.

[0013] In one feasible embodiment, the probe light reflector group includes: a first probe light reflector, a second probe light reflector, a third probe light reflector, and a fourth probe light reflector arranged sequentially; the probe light reflector group also includes a delay platform, on which the first probe light reflector and the second probe light reflector are disposed.

[0014] In one feasible embodiment, the first, second, third, and fourth detector light reflectors are all gold mirrors.

[0015] In one feasible embodiment, the first gas box contains a rare gas, and the second gas box contains a gas sample.

[0016] In one feasible embodiment, the first gas box and the second gas box are capillaries; the capillary includes a nozzle, the inner diameter of the capillary is 0.9 mm, the outer diameter of the capillary is 1.1 mm, and the diameter of the nozzle is 100 µm.

[0017] The switchable high-harmonic XUV spectral detection system provided by this invention has the following advantages:

[0018] 1. The detection mode of the present invention is switchable: The device adopts a mechanical all-optical measurement mode switching structure, which can flexibly select different XUV spectral detection methods according to the energy level characteristics, spectral energy range and experimental requirements of the sample to be tested, so as to achieve rapid and stable switching of detection modes.

[0019] 2. Furthermore, the present invention is a wide energy range and high precision detection system: the XUV spectral detection system combines a microchannel plate detection method with a large detection range and a CCD camera detection method with high detection precision, which can take into account both wide range detection and high precision measurement, thereby achieving a wide energy range and high resolution XUV spectral detection effect.

[0020] 3. Furthermore, the system stability of the present invention is improved: by adopting a modular XUV spectral processing system, the stability of XUV spectral generation, transmission and detection processes can be significantly improved, while reducing the complexity of experimental operation and optical path adjustment, and improving the ease of use, reliability and experimental repeatability of the system. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the structure of the high-order harmonic generation system in an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the spectral detection system in an embodiment of the present invention.

[0024] Figure 4 This is a diagram showing the detection results of the second optical path in an embodiment of the present invention.

[0025] Figure 5 This is a diagram showing the detection results of the first optical path in an embodiment of the present invention.

[0026] Figure Labels

[0027] Femtosecond laser source 1

[0028] Beam splitter 2

[0029] Pump light first reflecting mirror 3

[0030] Pump light second reflector 4

[0031] Pump light third reflecting mirror 5

[0032] First Gas Box 6

[0033] Aperture 7

[0034] First Tire Mirror 8

[0035] Hollow Mirror 9

[0036] Second gas box 10

[0037] First reflector of the probe light 11

[0038] Detector light second reflector 12

[0039] Detector light third reflector 13

[0040] Fourth reflector 14 for detecting light

[0041] Delay platform 15

[0042] Detector lens 16

[0043] First focal field grating 17

[0044] Displacement mechanism 18

[0045] Microchannel plate 19

[0046] Second tire mirror 20

[0047] Mirror 21

[0048] Second flat focal field grating 22

[0049] CCD camera 23

[0050] First optical path L1

[0051] Second optical path L2

[0052] Pump optical path L3

[0053] Probe optical path L4 Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "left side", "right side", "upper side", "lower side", "above", "below", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0055] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0056] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0057] This invention provides a switchable high-harmonic XUV spectral detection system, as shown in Figure 1, comprising: a femtosecond laser source 1, a high-harmonic generation system, and a spectral detection system arranged sequentially; the femtosecond laser source 1 is used to emit femtosecond laser, and the high-harmonic generation system is used to convert the femtosecond laser into XUV. As shown in Figure 3, the spectral detection system includes: 1) a displacement mechanism 18 and a first flat-focus grating 17 disposed on the displacement mechanism 18, the displacement mechanism 18 being used to move the first flat-focus grating 17 to contact the XUV; when the XUV contacts the first flat-focus grating 17, diffraction forms a first optical path L1, otherwise it forms a second optical path L2; 2) a microchannel plate 19 disposed in the first optical path L1 and a second tire mirror 20, a reflector 21, a second flat-focus grating 22, and a CCD camera 23 arranged sequentially in the second optical path L2.

[0058] In use, as shown in Figure 3, if a wide range of sample measurements is desired, the displacement mechanism 18 is adjusted so that the first flat focal field grating 17 contacts the XUV, thereby diffracting to form a first optical path L1. Finally, the microchannel plate 19 detects the XUV signal in the first optical path L1 to obtain the wide range of measurement results shown in Figure 5. If a high-precision sample measurement is desired, the displacement mechanism 18 is adjusted so that the first flat focal field grating cannot contact the XUV, thereby forming a second optical path L2. Finally, the CCD camera 23 detects the XUV signal in the second optical path L2 to obtain the high-precision measurement results shown in Figure 4.

[0059] Further, as shown in Figures 1 and 2, the high-harmonic XUV spectral detection system also includes a femtosecond laser beam splitter 2, which is used to split the femtosecond laser beam into pump light and probe light. The high-harmonic generation system includes: 1) a pump light reflector group and a first gas box 6 sequentially arranged in the pump light path L3, the first gas box 6 being used to convert the pump light into XUV; 2) an aperture 7, a first tire mirror 8, a hollow mirror 9, and a second gas box 10 sequentially arranged in the XUV light path, the hollow mirror 9 being located at the intersection of the pump light and the probe light; 3) a probe light reflector group and a probe light lens 16 sequentially arranged in the probe light path L4.

[0060] Further, as shown in Figures 1 and 2, the pump light reflector group includes: a first pump light reflector 3, a second pump light reflector 4, and a third pump light reflector 5 arranged sequentially. More specifically, the first pump light reflector 3 is a gold mirror, the second pump light reflector 4 is a reflecting focusing mirror, and the third pump light reflector 5 is a gold mirror.

[0061] Further, as shown in Figures 1 and 2, the probe light reflector group includes: a first probe light reflector 11, a second probe light reflector 12, a third probe light reflector 13, and a fourth probe light reflector 14 arranged sequentially; the probe light reflector group also includes a delay platform 15, on which the first probe light reflector 11 and the second probe light reflector 12 are disposed.

[0062] Furthermore, the focal length of the second pump light reflector 4 is 500 mm; the focal length of the probe light lens 16 is 400 mm; the focal length of the first tire mirror 8 is 150 mm; and the focal length of the second tire mirror 20 is 100 mm.

[0063] Furthermore, the first gas box 6 and the second gas box 10 are capillaries; each capillary includes a nozzle, the inner diameter of the capillary is 0.9 mm, the outer diameter of the capillary is 1.1 mm, and the diameter of the nozzle is 100 µm. Even further, the first gas box 6 contains a rare gas, and the second gas box 10 contains a gas sample.

[0064] Example

[0065] As shown in Figure 1, this embodiment provides a switchable high-harmonic XUV spectral detection device.

[0066] The femtosecond laser source 1 uses a commercial Ti:sapphire laser as the light source, and obtains a few-period femtosecond pulse laser after pulse broadening and compression. The few-period femtosecond pulse laser is split by a beam splitter 2 and input into a high-harmonic generation system. One pulse is focused into a first gas chamber 6 filled with argon gas, and XUV pulses are generated through the high-harmonic generation process, serving as the pump light; the other pulse serves as the probe light. The pump light and probe light are focused collinearly into a second gas chamber 10 filled with the gas sample to be tested, and the time delay between them is adjustable, used to excite and detect the energy level evolution and electron dynamics processes in the gas sample. The generated high-harmonic XUV spectrum is detected by the switchable XUV spectral detection system. Specifically, the XUV spectrum can be reflected by a switching grating and then entered into the microchannel plate 19 detection system for detection; alternatively, it can be input into the CCD camera 23 detection system without reflection by the switching grating.

[0067] Specifically, as shown in Figures 1 and 2, the femtosecond laser source 1 uses a commercial Ti:sapphire laser to broaden the output pulsed laser, obtaining a few-period femtosecond pulsed laser with a single-pulse energy of 2.5 mJ and a pulse width of 9.32 fs. After being split by the beam splitter 2, the femtosecond laser beams are input into the high-order harmonic generation system.

[0068] As shown in Figure 2, the laser beam passing through beam splitter 2 has high energy and serves as pump light. After entering the high-harmonic generation system, the pump light is reflected by the first pump light reflecting mirror 3, focused by the second pump light reflecting mirror 4, and then reflected by the third pump light reflecting mirror 5 before being focused inside the first gas box 6. The first gas box 6 is composed of capillaries and is filled with a rare gas (such as argon). The pump light interacts with the rare gas inside the first gas box 6 to generate high-harmonic XUV radiation pump light. The XUV pump light passes through aperture 7, is refocused by the first tire mirror 8, passes through the hollow mirror 9, and is focused inside the second gas box 10 to excite or detect the gas sample to be tested. The laser beam reflected by beam splitter 2 has low energy and serves as infrared detection light in the XUV spectrum. As shown in Figure 2, the detection light passes through the first detection light reflecting mirror 11 and the second detection light reflecting mirror 12, and is then reflected by the third detection light reflecting mirror 13 and input into the high-harmonic generation system. The input infrared detection light is reflected by the fourth reflector 14, focused by the lens 16, and then reflected by the hollow mirror 9, also focusing inside the second gas chamber 10. The second gas chamber 10 is filled with the gas sample to be tested. By scanning the time delay between the XUV pulse and the infrared pulse, the energy level evolution of the gas sample is encoded in the generated time-resolved XUV spectrum.

[0069] The generated XUV spectrum is then input into the spectral detection system. As shown in Figure 3, when the first flat-field grating 17 moves into the XUV optical path, the generated XUV spectrum is diffracted by the first flat-field grating 17 and imaged onto a horizontal focal plane. At the focal plane, a microchannel plate 19 is used for detection. During detection by the microchannel plate 19, light excites electrons at the front surface. These electrons are accelerated inside the microchannel plate 19, generating fluorescence corresponding to the XUV spectrum on the rear surface. The XUV spectrum is collected and recorded using a camera. Figure 3 As shown, when the first flat-field grating 17 moves out of the optical path, the generated XUV spectrum continues to propagate backward. After being focused by the second tire mirror 20 and reflected by the mirror 21, it is incident on the second flat-field grating 22. After diffraction, the signal generated at the focal plane of the XUV spectrum is collected and recorded by the CCD camera 23. By analyzing the XUV spectral delay scan data obtained by the spectral detection system, the energy level evolution process of the gas under excited state can be analyzed.

[0070] This embodiment describes a switchable high-harmonic XUV spectroscopy detection system for characterizing energy level evolution and ultrafast electron dynamics processes in gas samples. It addresses the challenges of balancing detection range and accuracy, as well as the high detection difficulty, in existing XUV spectroscopy characterization techniques. The experimental system can select and switch different detection modes based on the energy level characteristics of different samples and the required experimental accuracy, through a mechanical all-optical measurement mode switching structure. Furthermore, the system integrates a microchannel plate 19 detection system and a CCD camera 23 detection system, enabling both wide-range detection and high-precision measurement, thereby achieving wide-energy-domain, high-resolution XUV spectroscopy detection. In addition, delayed scanning requires high signal stability. By employing a modular XUV spectral processing system, the system's operational stability can be effectively improved, thereby enhancing the accuracy and reliability of experimental data.

[0071] Table 1 Component Comparison Parameter Table

[0072] Optical components parameter Pump light first reflecting mirror 3 Thorlabs PF10-03-M03 Pump light second reflector 4 Thorlabs CM508-500-M01 Pump light third reflecting mirror 5 Thorlabs PF10-03-M03 First Tire Mirror 8 ARW Optical Corporation STU-TM3 First reflector of the probe light 11 Thorlabs PF10-03-M03 Detector light second reflector 12 Thorlabs PF10-03-M03 Detector light third reflector 13 Thorlabs PF10-03-M03 Fourth reflector 14 for detecting light Thorlabs PF10-03-M03 Detector lens 16 Thorlabs LA1172-AB-ML First focal field grating 17 Hitachi 001-0640 Displacement mechanism 18 VT-50-11016 Second tire mirror 20 ARW Optical Corporation STU-TM2 Mirror 21 Thorlabs PF20-03-M03 Second flat focal field grating 22 Hitachi 001-0640 CCD camera 23 Andor Newton DO940P

[0073] In operation, the embodiments of the present invention can adopt the following steps:

[0074] Step 1: The laser output from the commercial Ti:sapphire femtosecond laser is stretched to generate a few-period femtosecond pulse laser.

[0075] Step 2: The few-period femtosecond pulse laser is split into pump light and probe light using beam splitter 2.

[0076] Step 3: Introduce pump light into the high-order harmonic generation system to ionize the rare gas, generate XUV pump light through the high-order harmonic process, and apply it to the gas sample to be tested to excite the gas sample to the corresponding excited state.

[0077] Step 4: Introduce the probe light into the high harmonic generation system and adjust the time delay between the pump light and the probe light so that the probe light irradiates the same gas sample after the gas sample is excited, thereby driving the generation of time-resolved high harmonic XUV spectra.

[0078] Step 5: Select and switch the detection mode to collect and record time-resolved high-harmonic XUV spectra.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A switchable high-harmonic XUV spectral detection system, characterized in that, include: The femtosecond laser source, the high-order harmonic generation system, and the spectral detection system are set up sequentially. The femtosecond laser source is used to emit femtosecond lasers, and the high-order harmonic generation system is used to convert femtosecond lasers into XUVs; The spectral detection system includes: 1) a displacement mechanism and a first flat focal field grating disposed on the displacement mechanism, wherein the displacement mechanism is used to move the first flat focal field grating to contact XUV; When the XUV contacts the first flat focal field grating, it diffracts to form the first optical path, and conversely, it forms the second optical path; 2) a microchannel plate is provided in the first optical path and a second tire mirror, a reflector, a second flat focal field grating and a CCD camera are provided in the second optical path in sequence.

2. The high-harmonic XUV spectral detection system according to claim 1, characterized in that, Also includes: A femtosecond laser beam splitter, wherein the femtosecond laser beam splitter is used to split a femtosecond laser beam into a pump beam and a probe beam; The high-order harmonic generation system includes: 1) a pump light reflector group and a first gas box sequentially disposed in the pump light path, wherein the first gas box is used to convert the pump light into XUV; 2) An aperture, a first tire mirror, a hollow mirror, and a second gas box are sequentially arranged in the XUV optical path, with the hollow mirror located at the intersection of the pump light and the probe light; 3) A probe light reflector group and a probe light lens are sequentially arranged in the probe light path.

3. The high-harmonic XUV spectral detection system according to claim 2, characterized in that, The pump light reflector group includes: a first pump light reflector, a second pump light reflector, and a third pump light reflector arranged in sequence.

4. The high-harmonic XUV spectral detection system according to claim 3, characterized in that, The first pump light reflecting mirror is a gold mirror, the second pump light reflecting mirror is a reflecting focusing mirror, and the third pump light reflecting mirror is a gold mirror.

5. The high-harmonic XUV spectral detection system according to claim 4, characterized in that, The focal length of the second reflector for the pump light is 500 mm.

6. The high-harmonic XUV spectral detection system according to claim 2, characterized in that, The focal length of the probe lens is 400 mm; and / or, the focal length of the first tire mirror is 150 mm; and / or, the focal length of the second tire mirror is 100 mm.

7. The high-harmonic XUV spectral detection system according to claim 2, characterized in that, The probe light reflector group includes: a first probe light reflector, a second probe light reflector, a third probe light reflector, and a fourth probe light reflector arranged sequentially; the probe light reflector group also includes a delay platform, on which the first probe light reflector and the second probe light reflector are disposed.

8. The high-harmonic XUV spectral detection system according to claim 7, characterized in that, The first, second, third, and fourth reflectors of the probe light are all gold mirrors.

9. The high-harmonic XUV spectral detection system according to claim 2, characterized in that, The first gas box contains rare gases, and the second gas box contains gas samples.

10. The high-harmonic XUV spectral detection system according to claim 2, characterized in that, The first gas box and the second gas box are capillary tubes; the capillary tube includes a nozzle, the inner diameter of the capillary tube is 0.9 mm, the outer diameter of the capillary tube is 1.1 mm, and the diameter of the nozzle is 100 µm.

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