Laser generating device, attosecond pulse laser generating and detecting device and measuring method

Abstract

The invention provides a laser generating device, an attosecond pulse laser generating and detecting device and a measuring method. According to the laser generation device, the attosecond pulse laser generation and detection device and the measurement method, attosecond pulses with high energy, high photon energy, wide spectrum and short pulse width can be generated, the time domain characteristics of the attosecond pulses are measured through a delay-locked pumping detection experiment, and the attosecond pulse spectrum is measured through a flat-field grating spectrometer. And the generated attosecond pulse can be applied to excite electron dynamics in the material, and a transient absorption spectrum of the material is measured by a spectrograph, so that the electron dynamics process in the material is researched. The device has the advantages of high driving laser energy, short pulse width, dual wavelengths, high attosecond pulse energy, high photon energy, wide frequency spectrum, high time resolution precision, high stability and the like, can be widely applied to research on atomic inner shell ionization delay, Auger effect, electronic correlation, Van Node resonance and the like, and has good application prospect and commercial value.

Description

Technical Field

[0001] The invention belongs to the field of lasers, and in particular relates to a laser generating device, an attosecond pulse laser generating and detecting device and a measuring method. Background Art

[0002] The generation of ultrashort pulses is the key to exploring the dynamic behavior of matter on a shorter time scale. Femtosecond pulses can be used to probe molecular dynamics, while some properties of matter are determined by the motion of electrons, which has a time scale of hundreds of attoseconds (10 -18 Seconds), in order to observe electron dynamics, an attosecond light source is needed. The gas high-order harmonics generated by the interaction between infrared femtosecond pulse lasers and rare gas atoms is one of the most important methods to obtain attosecond pulses. In the frequency domain, the high-order harmonics correspond to an odd harmonic comb with an interval of 2 times the driving laser frequency. In the time domain, it is an attosecond pulse train with an interval of half a laser cycle. Single attosecond pulses can be separated from the attosecond pulse train through amplitude gating, polarization gating, ionization gating, double light gate gating and other methods, which can be used to detect electron dynamics and carry out research in the field of material science.

[0003] However, the gas high-order harmonic generation process has the problem of low conversion efficiency, which makes the energy of the attosecond pulses it produces low. Experimentally, the most direct way to increase the energy of attosecond pulses is to increase the single pulse energy of the driving laser. According to the high-order harmonic generation process, a few-cycle femtosecond pulse driving light is more conducive to obtaining a single attosecond pulse. Secondly, the photon energy in the high-order harmonic cutoff region is proportional to the square of the driving laser wavelength. The photon energy in the cutoff region can be increased by increasing the central wavelength of the driving laser. In summary, high-energy, wavelength-tunable few-cycle femtosecond lasers are the key to generating high-energy, high-photon energy attosecond pulses, but the generation of high-energy attosecond pulses is currently not possible, which greatly limits the application of attosecond pulses. Summary of the invention

[0004] Therefore, the purpose of the present invention is to overcome the defects in the prior art and provide a laser generating device, an attosecond pulse laser generating and detecting device and a measuring method. The laser generating device, the high-energy attosecond pulse laser generating and detecting device and the measuring method of the present invention can be used for the experimental device of generating, measuring and applying attosecond pulses with high energy, high photon energy and a spectral range covering the extreme ultraviolet to the soft X-ray band. The laser can output a few-cycle femtosecond pulse laser with a central wavelength of 860nm and 2170nm respectively. The 860nm few-cycle high-energy femtosecond pulse laser can drive the rare gas to generate high-energy high-order harmonics; the 2170nm few-cycle high-energy femtosecond pulse laser can increase the photon energy in the high-order harmonic cutoff region. Furthermore, the synthetic light field of the 860nm and 2170nm lasers can be used to improve the conversion efficiency of the high-order harmonics and expand the photon energy in the cutoff region; using a suitable gating method, a wide spectrum short pulse width attosecond pulse can be obtained from the high-order harmonics generated by the above three femtosecond pulse lasers. The device is equipped with a time-of-flight spectrometer and a spectrometer, which can characterize the time and frequency characteristics of attosecond pulses respectively. The generated attosecond pulses can be used to carry out research in the fields of attosecond transient absorption spectroscopy and inner shell electron dynamics, and promote material science research on the attosecond time scale.

[0005] Before describing the present invention, the terms used in this article are defined as follows:

[0006] The term "femtosecond" refers to a unit of measurement for the length of time, 1 femtosecond is equal to one quadrillionth of a second, or 1e -15 Second, also called femtosecond, is abbreviated as fs.

[0007] The term "attosecond" refers to: An international unit of time equal to 10 -18 Second, or 1 / 1000 femtosecond, also known as attosecond, the English name is attosecond, abbreviated as as.

[0008] The term "high energy" refers to energy in the energy range ≥ 100 nJ.

[0009] The term "high photon energy" refers to energy in the photon energy range ≥ 120 eV.

[0010] The term "extreme ultraviolet" refers to electromagnetic radiation with a wavelength of 10nm to 121nm in the electromagnetic spectrum.

[0011] The term "soft X-ray band" refers to electromagnetic radiation with a wavelength of 0.01nm to 10nm.

[0012] The term "period" refers to: the carrier period of a femtosecond pulse, that is, the process of a femtosecond pulse propagating a carrier from the beginning to the end is a period.

[0013] The term "pulse width", abbreviated as "pulse width", refers to the duration of a laser pulse, that is, the length of time from the start to the end of the pulse, measured in femtoseconds (fs).

[0014] The term "few-cycle" means that the duration (pulse width) of a femtosecond pulse is less than 10 cycles, i.e., a few-cycle.

[0015] The term "loose focusing" means that in experiments, a focusing mirror such as a concave reflector or a convex lens is usually used to focus the femtosecond laser. As the focal length of the focusing mirror decreases, the smaller the focused spot becomes, and the better the focusing effect becomes. Usually, focusing with a focusing mirror with a focal length > 1m is called loose focusing.

[0016] To achieve the above-mentioned object, the first aspect of the present invention provides a pulse laser generating device, the pulse laser generating device comprising: an oscillator, a pump source, a stretcher, an amplifier and a compressor; wherein:

[0017] The oscillator generates two output lasers, the first output laser enters the pump source for amplification and then is transmitted to the amplifier; the other output laser enters the stretcher for spectrum broadening and then enters the amplifier, and then the stretched laser is amplified by the pump light output by the pump source, and then enters the compressor for pulse width compression, thereby obtaining the pulse laser;

[0018] Preferably, the pump source is a picosecond pump source.

[0019] According to the pulse laser generating device of the first aspect of the present invention, the number of the stretchers and the number of the amplifiers are both 2, and the other output laser is divided into two paths and enters different stretchers for spectrum broadening and then enters different amplifiers for amplification;

[0020] Preferably, the two stretchers have a stretching range of 1580-2450 nm and 680-1060 nm, more preferably 1800-2350 nm and 720-1050 nm, and most preferably 2000-2200 nm and 800-900 nm; and / or

[0021] Preferably, the amplification ranges of the two amplifiers are 1580-2450 nm and 680-1060 nm, more preferably 1800-2350 nm and 720-1050 nm, and most preferably 2000-2200 nm and 800-900 nm.

[0022] According to the pulse laser generating device of the first aspect of the present invention,

[0023] The wavelengths of the pulsed laser are 680-1080 nm and 1580-2450 nm, preferably 720-1050 nm and 1800-2350 nm, more preferably 800-900 nm and 2000-2200 nm;

[0024] The energy of the pulse laser is 1 to 7 mJ, preferably 5 to 7 mJ, more preferably 6 to 7 mJ; and / or

[0025] The pulse width of the pulse laser is 5-11.5 fs and 18-40 fs, preferably 7-8 fs and 20-30 fs, and most preferably 7 fs and 25 fs.

[0026] A second aspect of the present invention provides an attosecond pulse laser generation and detection device, the attosecond pulse laser generation and detection device comprising:

[0027] The pulse laser generating device according to the first aspect, and

[0028] A vacuum chamber and the following components arranged inside the vacuum chamber: a pump detection device, a detection gas target, a time-of-flight spectrometer, a detection tire mirror and a spectrometer;

[0029] Wherein, the femtosecond pulse laser generated by the pulse laser generating device described in the first aspect passes through the pump detection device, and generates attosecond pulse laser in the pump detection device, and the attosecond pulse laser passes through the detection gas target, the time-of-flight spectrometer, the detection tire mirror and the spectrometer in sequence, wherein the electrons obtained by the attosecond pulse laser ionizing the gas of the detection gas target enter the time-of-flight spectrometer;

[0030] Preferably, the time-of-flight spectrometer is located next to the detection gas target.

[0031] According to the attosecond pulse laser generation and detection device of the second aspect of the present invention, the pump detection device comprises: a beam splitter, a pump light focusing system, a gas target, a metal film, a pump light tire mirror, a delay system, a detection light focusing system and a beam combining mirror; wherein,

[0032] The femtosecond pulse laser is divided into pump light and detection light by a beam splitter. The pump light is loosely focused by a pump light focusing system to generate high-order harmonics in a gas target, and then passes through the metal film to obtain attosecond pulse laser, which then passes through a pump light tire mirror to reach a beam combining mirror. The detection light passes through a delay system and the detection light focusing system in sequence, and is combined with the attosecond pulse laser that reaches the beam combining mirror and converges to the detection gas target.

[0033] Preferably, the laser detection device further comprises a solid target, and the solid target is located between the tire detection mirror and the spectrometer.

[0034] According to the attosecond pulse laser generating and detecting device of the second aspect of the present invention,

[0035] The pump light focusing system and the detection light focusing system are both selected from one or more of the following mirror systems: spherical mirrors, tire mirrors, parabolic mirrors, ellipsoidal mirrors, cylindrical mirrors, preferably spherical mirrors and / or parabolic mirrors, most preferably spherical mirrors;

[0036] The focal spot diameters of the pump light focusing system and the detection light focusing system are less than 1 mm, preferably 0.2 to 0.5 mm, and more preferably 0.25 to 0.3 mm;

[0037] The gas of the pump light gas target and the detection gas target is a rare gas, preferably selected from one or more of the following: helium, neon, argon, krypton, xenon, more preferably selected from one or more of the following: neon, argon, krypton, xenon, further preferably selected from one or more of the following: neon, argon, krypton;

[0038] The generating gas target and the detecting gas target are a gas pool and / or a gas jet;

[0039] The metal film is selected from one or more of the following: Al, Zr, Ti, Zn, Mo, Sn, preferably selected from one or more of the following: Al, Zr, Ti, Zn, more preferably Al and / or Zr;

[0040] The beam combiner is selected from one or more of the following: a perforated beam combiner, a polarization beam combiner, a wavelength beam combiner, and the most preferred one is a perforated beam combiner; and / or

[0041] The time-delay system comprises: a time-delay reflector, a time-delay vacuum electric translation stage and a time-delay piezoelectric translation stage. The time-delay reflector is preferably located on the time-delay vacuum electric translation stage and the time-delay piezoelectric translation stage.

[0042] According to the attosecond pulse laser generation and detection device of the second aspect of the present invention, the spectrometer comprises: a slit, a grating, a grating electric translation stage, a spectrometer electric turntable, a microchannel plate for converting photon signals into electrical signals, a fluorescent screen for converting electrical signals into fluorescent signals, and a camera for collecting fluorescent signals on the fluorescent screen; wherein,

[0043] The wavelength range of the grating is 20-80 nm or 5-20 nm; and / or

[0044] The camera is a CCD camera.

[0045] According to the attosecond pulse laser generation and detection device of the second aspect of the present invention, the attosecond pulse laser generation and detection device further comprises: a laser source and a locking feedback system; wherein,

[0046] The laser source is a continuous laser, and its wavelength is preferably 500-638 nm, more preferably 500-550 nm, and most preferably 532 nm; the laser source preferably passes through the pump-detection device to reach the locking feedback system;

[0047] The locking feedback system is located after the beam combiner; and / or

[0048] The laser source enters the pump-detection device through a beam splitter, spatially overlaps at the locking feedback system to generate interference fringes, and together with the time-delay voltage level shifting stage, forms a feedback locking system.

[0049] A third aspect of the present invention provides a method for measuring attosecond pulse spectrum, the method comprising using the attosecond pulse laser generating and detecting device described in the second aspect;

[0050] Preferably, the method for measuring the attosecond pulse spectrum includes: the pulse laser generating device emits a femtosecond pulse laser, and after passing through the pump detection device, the combined attosecond pulse laser and the detection light are converged to the detection gas target to ionize the gas to obtain electrons, a time-of-flight spectrometer measures the flight time of the electrons, and detects the time width of the attosecond pulse laser, and when the attosecond pulse laser passes through the detection tire mirror and reaches the spectrometer without passing through the solid target, the attosecond pulse spectrum is detected.

[0051] A fourth aspect of the present invention provides a method for measuring transient absorption spectrum, the method for measuring transient absorption spectrum comprising using the attosecond pulse laser generation and detection device described in the second aspect;

[0052] Preferably, the method for measuring the transient absorption spectrum includes: the pulse laser generating device emits a femtosecond pulse laser, and after passing through the pump detection device, the generated attosecond pulse laser and the detection light are converged to the detection gas target to achieve time and space overlap, and then incident on the solid target through the detection tire mirror, and then the electron dynamics inside the solid target are stimulated to reach the spectrometer, and the transient absorption spectrum of the solid material in the solid target is measured by the spectrometer.

[0053] According to a preferred embodiment of the present invention, the present invention relates to attosecond pulse generation, attosecond pulse time and spectral characteristic characterization, transient absorption spectrum measurement, and particularly to a device for generating high-energy attosecond pulses by driving a dual-wavelength, high-energy, short-cycle femtosecond pulse laser.

[0054] The device for generating, measuring and applying high-energy attosecond pulses of the present invention comprises: a vacuum chamber, a femtosecond pulse laser, a pump detection system, a detection gas target, a vacuum electric translation stage, a spectrometer electric turntable, a rare gas, a metal film, a detection tire mirror, a delay system, a 532nm laser source, a time-of-flight spectrometer, a flat-field grating spectrometer, solid materials, etc.

[0055] Furthermore, the vacuum chamber can provide 1×10 -8 mbar vacuum degree, its types include: mechanical pump, molecular pump, ion pump, cryogenic pump, sublimation pump and one of their combined systems.

[0056] Furthermore, the driving laser includes a short-cycle high-energy infrared laser with a central wavelength of 860nm, a pulse width of 7fs, and a single pulse energy of 7mJ, and a short-cycle high-energy mid-infrared laser with a central wavelength of 2170nm, a pulse width of 25fs, and a single pulse energy of 7mJ. These two lasers can also form a two-color coherent light field.

[0057] Furthermore, the pump-detection system comprises a plurality of high-reflectivity mirrors, a plurality of apertures, beam splitters, and a perforated beam combiner.

[0058] The laser is introduced into the vacuum cavity through the high reflectivity mirrors, the aperture is used to collimate the light path and adjust the laser spot diameter, the beam splitter is used to split the laser into two beams of pump and detection light, and the perforated beam combiner is used to combine the pump and detection beams.

[0059] Furthermore, the focusing system includes types of: a spherical mirror, a tire mirror, a parabolic mirror, an ellipsoidal mirror, a cylindrical mirror and a combination thereof, which can achieve a focal spot diameter of less than 1 mm.

[0060] Furthermore, the pump light gas target and the detection gas target are one of a gas pool and a gas nozzle, and are respectively installed on the pump light gas target electric displacement stage and the detection gas target electric displacement stage, and can realize free movement in three dimensions.

[0061] Furthermore, the rare gas includes: one of helium, neon, argon, krypton and xenon.

[0062] Furthermore, the metal film includes Al, Zr, Ti, Zn, etc., or one of their combined systems.

[0063] Furthermore, the tire mirror can be used to focus and image attosecond pulses.

[0064] Furthermore, the delay system includes a delay reflector, a delay vacuum electric translation stage and a delay high-precision piezoelectric translation stage, which can adjust the delay between the gas pump detection light paths with attosecond accuracy.

[0065] Furthermore, the 532nm laser source is a continuous laser, which is used to lock the pump-probe optical path delay.

[0066] Furthermore, the time-of-flight spectrometer can be used to measure the electron time-of-flight spectrum. The minimum electron energy that can be measured by the time-of-flight spectrometer is 20 eV.

[0067] Furthermore, the flat-field grating spectrometer comprises a slit, two gratings with different engraved lines, an electric translation stage, an electric turntable, a microchannel plate, a fluorescent screen and a CCD camera.

[0068] Among them, the wavelength ranges of the two gratings with different engraved lines are 20-80nm or 5-20nm respectively, the electric translation stage can realize the free switching of the two gratings in the vertical direction, the electric turntable can realize clockwise and counterclockwise rotation of more than 30°, the microchannel plate is used to convert photon signals into electrical signals, the fluorescent screen is used to convert electrical signals into fluorescent signals, and the CCD camera is used to collect fluorescent signals on the fluorescent screen.

[0069] Further, the solid material includes: one of copper sulfide, gallium selenide, gallium telluride, gallium sulfide, germanium selenide, tungsten ditelluride, molybdenum ditelluride, hafnium disulfide, hafnium diselenide, cobalt diselenide, cobalt ditelluride, rhenium diselenide, rhenium ditelluride, tin disulfide, tin diselenide, niobium disulfide, niobium diselenide, titanium disulfide, titanium diselenide, tantalum disulfide, tantalum diselenide, zirconium disulfide, zirconium ditelluride, bismuth sulfide, bismuth selenide, bismuth telluride, gallium arsenide, zinc oxide, magnesium oxide, and silicon dioxide.

[0070] According to another preferred embodiment of the present invention, a femtosecond pulse is used as a light source to generate a high-energy attosecond pulse in a vacuum device, and the attosecond pulse is characterized and applied.

[0071] According to another preferred embodiment of the present invention, the method for measuring attosecond pulse width and spectrum comprises:

[0072] The femtosecond pulse laser is divided into pump light and detection light by a beam splitter. The pump light is loosely focused by a pump light focusing system to generate high-order harmonics in a gas target, passes through the metal film to obtain an attosecond pulse, and then passes through a tire mirror to reach a beam combining mirror. The detection light passes through a delay system and a detection light focusing system in sequence, and is combined with the attosecond pulse that reaches the beam combining mirror and converges to the detection gas target together. By adjusting the angle of the beam combining mirror and the delay of the delay system, the attosecond pulse and the detection light are overlapped in time and space on the detection gas target.

[0073] At the detection gas target, the attosecond pulse interacts with the gas atoms of the detection gas target, ionizes the electrons in the atoms out of the bound nuclei and becomes free electrons, and the detection light modulates the momentum of the free electrons. The time-of-flight spectrometer measures the two-photon transition interference of the electrons to reconstruct the attosecond pulse electron energy spectrum or attosecond streak energy spectrum to obtain the time domain characteristics of the attosecond pulse;

[0074] When the attosecond pulse passes through the perforated mirror, it is directly imaged by the tire mirror and then incident on the spectrometer to measure the attosecond pulse spectrum;

[0075] The method for measuring the transient absorption spectrum includes: after achieving the time and space overlap of the attosecond pulse and the detection light on the detection gas target, the attosecond pulse and the detection light are incident on the solid target through the detection tire mirror to stimulate the electron dynamic process inside the solid material, and the transient absorption spectrum of the solid material is measured by a spectrometer, and the reflection and transmission transient absorption spectra of the solid material can be measured respectively.

[0076] The purpose of the present invention is to provide a set of high-energy, high-photon energy attosecond pulse generation, measurement and application devices, which can use dual-wavelength, high-energy, few-cycle femtosecond pulse lasers to generate high-energy, high-photon energy attosecond pulses, measure the time and spectral characteristics of attosecond pulses, and use attosecond pulses to measure the transient absorption spectrum of materials.

[0077] The present invention is based on a high-energy attosecond pulse generation, measurement and application device. It can use a central wavelength of 860nm, 2170nm, a few-cycle high-energy femtosecond pulse laser or a coherent synthetic light field of two lasers to react with rare gases to generate high-energy, high-photon energy, wide-spectrum and short-pulse-width attosecond pulses. The time domain characteristics of the attosecond pulses are measured by a time-delay locked pump-probe experiment, and the attosecond pulse spectrum is measured by a flat-field grating spectrometer. The generated attosecond pulses can also be used to excite the electron dynamics inside the material, and the transient absorption spectrum of the material is measured by a spectrometer, and then the electron dynamics process in the material is studied. The present invention is a multifunctional device integrating attosecond pulse generation, measurement and application. It has the advantages of high femtosecond pulse laser energy, short pulse width, dual wavelength, high attosecond pulse energy, high photon energy, wide spectrum, high time resolution accuracy, high stability, etc. It can be widely used to study atomic inner shell ionization delay, Auger effect, electron correlation, Fano resonance, etc., and has good application prospects and commercial value.

[0078] Compared with the prior art, the laser generating device, attosecond pulse laser generating and detecting device and measuring method of the present invention may have but are not limited to the following beneficial effects:

[0079] 1. The laser generating device, attosecond pulse laser generating and detecting device and measuring method of the present invention can use the central wavelength 860nm, 2170nm few-cycle high-energy femtosecond pulse laser or the coherent synthesis light field of the two lasers to react with rare gas to generate high-energy, high-photon energy, wide-spectrum short-pulse attosecond pulses, measure the time domain characteristics of attosecond pulses through time-delay locked pump-probe experiments, and measure the attosecond pulse spectrum with a flat-field grating spectrometer. The generated attosecond pulses can also be used to excite the electron dynamics inside the material, and the transient absorption spectrum of the material can be measured with a spectrometer, thereby studying the electron dynamics process inside the material.

[0080] 2. The present invention is a multifunctional device integrating attosecond pulse generation, measurement and application. It has the advantages of high femtosecond pulse laser energy, short pulse width, dual wavelength, high attosecond pulse energy, high photon energy, wide spectrum, high time resolution accuracy, high stability, etc. It can be widely used in the study of atomic inner shell ionization delay, Auger effect, electron correlation, Fano resonance, etc., and has good application prospects and commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, wherein:

[0082] Figure 1 A schematic diagram of a laser generating device of the present invention is shown.

[0083] Figure 2 A schematic diagram of the attosecond pulse laser generation and detection device of the present invention is shown.

[0084] Description of reference numerals:

[0085] 1. Vacuum cavity; 2. Beam splitter; 3. Pump light; 4. Pump light focusing system; 5. Generate gas target (take gas pool as an example); 6. Metal film; 7. Pump light tire mirror; 8. Beam combiner (take punched beam combiner as an example); 9. Detection light; 10. Delay system; 11. Detection light focusing system; 12. Detection gas target (take gas nozzle as an example); 13. Time-of-flight spectrometer; 14. Locking feedback system; 15. Detection tire mirror; 16. Solid target; 17. Spectrometer. DETAILED DESCRIPTION

[0086] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. However, it should be understood that these embodiments are only used for more detailed and specific description and should not be understood as limiting the present invention in any form.

[0087] This section generally describes the materials and test methods used in the experiments of the present invention. Although many materials and operating methods used to achieve the purpose of the present invention are well known in the art, the present invention is still described as detailed as possible. It is clear to those skilled in the art that in the context, if not specifically stated, the materials and operating methods used in the present invention are well known in the art.

[0088] Example 1

[0089] This embodiment is an exemplary description of the laser generating device of the present invention.

[0090] Figure 1 The schematic diagram of the laser generating device for generating femtosecond pulse laser in the present invention is shown. The oscillator has two output lights, one of which enters the picosecond pump source for amplification, and the picosecond pump source outputs four pump lights to the amplifier. The other laser is divided into two paths and enters the 800nm ​​and 2μm stretchers for spectrum broadening respectively. The broadened lasers enter the 800nm ​​and 2μm amplifiers respectively, and the pump light output by the picosecond pump source is used to amplify the broadened lasers. The amplified lasers then enter the compressor for pulse width compression, and finally obtain high-energy and low-cycle femtosecond pulse lasers.

[0091] Femtosecond pulse lasers include a few-cycle high-energy infrared femtosecond pulse laser with a central wavelength of 860nm, a repetition rate of 1kHz, a pulse width of 7fs, a single pulse energy of 7mJ, and a stable carrier-envelope phase; and a few-cycle high-energy mid-infrared femtosecond pulse laser with a central wavelength of 2170nm, a repetition rate of 1kHz, a pulse width of 25fs, a single pulse energy of 7mJ, and a stable carrier-envelope phase; the two lasers can also be combined into a synthetic coherent light field. Compared with 800nm ​​lasers, the high-order harmonic photons generated by 2μm lasers have higher energy, even reaching the water window band, making it easier to obtain high-energy single attosecond pulses with shorter pulse widths.

[0092] like Figure 1 As shown, the pulse laser generating device of the present invention includes 800nm ​​laser output and 2μm laser output; the 800nm ​​laser output corresponds to the central wavelength of 860nm, repetition frequency of 1kHz, pulse width of 7fs, single pulse energy of 7mJ, and a few-cycle high-energy infrared femtosecond pulse laser with stable carrier-envelope phase; the 2μm laser output corresponds to the central wavelength of 2170nm, repetition frequency of 1kHz, pulse width of 25fs, single pulse energy of 7mJ, and a few-cycle high-energy mid-infrared femtosecond pulse laser with stable carrier-envelope phase.

[0093] The pulse laser generator can only output all the laser output from the picosecond pump source to the 800nm ​​amplifier, and finally output 800nm ​​femtosecond pulse laser with a single pulse energy of 7mJ at the 800nm ​​output position. This output light corresponds to Figure 2 The femtosecond laser in Figure 2 Attosecond pulse laser generation and detection are performed in the vacuum chamber 1 shown in the figure; the femtosecond pulse laser generation device can also output all the laser output by the picosecond pump source to the 2μm amplifier, and finally output a femtosecond pulse laser with a single pulse energy of 7mJ at the 2μm output position. This output light corresponds to Figure 2 The femtosecond laser in Figure 2 Attosecond pulse laser generation and detection are performed in the vacuum chamber 1 shown in the figure; the femtosecond pulse laser generating device can also divide the laser output by the picosecond pump source equally to the 800nm ​​amplifier and the 2μm amplifier, and finally output femtosecond pulse laser at the 800nm ​​output and 2μm output positions at the same time. At this time, the single pulse energy of the 800nm ​​and 2μm femtosecond pulse lasers is 3.5mJ, and the 800nm ​​laser and the 2μm femtosecond pulse laser are both 3.5mJ. Figure 2 The femtosecond pulses are coherently combined at the position shown, and the synthesized laser enters Figure 2 Attosecond pulse laser generation and detection are carried out in the vacuum chamber 1. The coherently synthesized light field can not only overcome the limitation on the pulse width of femtosecond pulse laser, but also improve the generation efficiency of attosecond pulses by controlling the electron orbit, thereby obtaining high-energy attosecond pulses.

[0094] Example 2

[0095] This embodiment is an exemplary description of the attosecond pulse laser generation and detection device and measurement method of the present invention.

[0096] like Figure 2 FIG. 1 is a schematic diagram of a device for generating, detecting and applying high-energy attosecond pulses in the present invention. The femtosecond pulse laser generated by the laser generating device is introduced into the vacuum chamber 1 through a reflector and an aperture. The vacuum degree of the vacuum chamber in this embodiment is 1×10 -8 mbar as an example, the laser entering the vacuum chamber is divided into pump light 3 and detection light 9 by the beam splitter 2. The pump light 3 is loosely focused by the pump light focusing system 4 to the gas target 5 (taking the gas pool as an example), and the peak power density at the focus reaches 10 14 -10 15 W / cm 2Order of magnitude, in this embodiment, the pump light focusing system 4 takes a concave reflector as an example. The loose focusing method can increase the length of the laser along the propagation direction, increase the action length of the laser and the gas, improve the high-order harmonic yield, and obtain high-energy high-order harmonics. After the high-order harmonics pass through the metal film 6, the remaining infrared laser is filtered out to obtain attosecond pulse laser, and the continuous harmonic spectrum close to the cutoff region can also be obtained by amplitude selection, which corresponds to a single attosecond pulse in time. The generated attosecond pulse laser is focused by the pump light tire mirror 7, passes through the beam combiner 8 (taking the perforated beam combiner as an example) and reaches the detection gas target 12 (taking the gas nozzle as an example). The spot of the attosecond pulse laser at the detection gas target is a 1:1 imaging of the spot at the generation gas target. The detection gas target is mounted on the detection gas target electric displacement table, which can realize free movement in three dimensions. In this embodiment, the rare gas in the detection gas target is taken as Ne as an example, and the metal film is taken as Zr as an example.

[0097] The other detection light 9 passes through the delay system 10 to adjust the delay of the detection light relative to the pump light. The delay system includes a high-precision delay voltage-level shifter and a delay voltage-level shifter that can adjust the delay between the pump and detection light paths with attosecond precision. After the delay is adjusted, the detection light is focused by the detection light focusing system 11. In this embodiment, the detection light focusing system 11 takes a concave reflector as an example, and then reflects through a beam combiner 8 (taking a perforated beam combiner as an example), and then combines with the attosecond pulse laser that passes through the perforated beam combiner and converges together onto a detection gas target 12 (taking a gas nozzle as an example). By adjusting the angle of the perforated beam combiner and the delay of the delay line, the attosecond pulse laser and the detection light can be overlapped in time and space on the gas nozzle. The detection light path and the pump light path together constitute a pump detection device. At the detection gas target position, the attosecond pulse laser interacts with the gas atoms, ionizing the electrons in the atoms from the bound nuclei to become free electrons. The detection light modulates the momentum of the free electrons, and the time-of-flight spectrometer 13 measures the electron energy spectrum that changes with the delay between the attosecond pulse and the femtosecond detection pulse. When the attosecond pulse train ionizes the gas, the time-of-flight spectrometer measures the two-photon transition interference of the electrons to reconstruct the attosecond pulse electron energy spectrum; when a single attosecond pulse ionizes the gas, the time-of-flight spectrometer measures the attosecond streak electron energy spectrum of the electrons. The time-domain characteristics of the attosecond pulse can be obtained by inverting and reconstructing the electron energy spectrum.

[0098] Like femtosecond pulses, 532nm continuous laser light passes through the pump-probe optical path and spatially overlaps at the locking feedback system 14 to produce interference fringes. Together with the high-precision piezoelectric shift stage, the pump-probe optical path delay is locked with attosecond accuracy, improving the stability and time resolution accuracy of the pump-probe experiment, making the attosecond pulse width measured by the time-of-flight spectrometer more accurate.

[0099] After the attosecond pulse is imaged by the detection tire mirror 15, it is incident on the flat-field grating spectrometer 17, and the spectrometer can measure the attosecond pulse spectrum. The flat-field grating spectrometer 17 is composed of a slit, two gratings, a microchannel plate, a fluorescent screen, and a CCD camera. The slit is used to adjust the size of the spatial light field of the attosecond pulse entering the spectrometer to reduce the impact of the spatial distribution on the spatial resolution of the spectrometer. The two gratings are 300 lines and 1200 lines respectively, and the wavelength ranges that can be split are 20-80nm or 5-20nm respectively. The two gratings are placed on the electric translation stage and the electric turntable at the same time. According to the wavelength range of the attosecond pulse actually generated, the translation stage is moved to switch the grating of the appropriate wavelength; the turntable is rotated to adjust the grating angle to optimize the detector resolution. After the attosecond pulse is split by the grating, it is incident on the microchannel plate, which amplifies the split photon signal, and the amplified signal is imaged on the fluorescent screen. The CCD camera records the light signal on the fluorescent screen, thereby obtaining the attosecond pulse spectrum. The flat-field grating spectrometer can be used not only to measure attosecond pulse spectra, but also to measure transient absorption spectra of materials. When the solid target 16 is placed in the optical path, the attosecond pulse is first incident on the solid target to excite the electron dynamics process inside the material, and the spectrometer measures the transient absorption spectrum of the material; the device can also be switched to measure the transient absorption spectrum of reflective materials. Analysis of the measured transient absorption spectrum can obtain information on the electron dynamics inside the material, thereby studying the electron dynamics process with attosecond time precision.

[0100] It can be seen that the attosecond pulse generation, measurement and application device designed in this embodiment can generate high-energy, high-photon energy, broadband single attosecond pulses, and fully characterize the time and spectral characteristics of attosecond pulses. Attosecond pulses can also be used to measure the transient absorption spectrum of materials, providing attosecond time resolution for studying the internal electron dynamics of matter.

[0101] The femtosecond pulse laser described in this embodiment has the characteristics of few cycles, high energy, and dual wavelengths, and can produce attosecond pulses with higher photon energy, shorter pulse width, and higher pulse energy when interacting with gas. The present invention is a multifunctional device integrating attosecond pulse generation, measurement, and application, and has the advantages of high photon energy, wide spectrum, high time resolution accuracy, multiple functions, wide applicable system, and high stability. It can be widely used in the study of atomic inner shell ionization delay, electron post-collision effect in molecular atoms, Auger effect, and other ultrafast dynamics of electrons, and has good application prospects and commercial value.

[0102] Although the effects of some embodiments are shown above, those skilled in the art should understand that according to the concept of the present invention, the aforementioned other embodiments without specific effects or other technical solutions of the present invention not shown in the embodiments can also achieve the following technical effects stated in the invention content section that are equivalent to the embodiments:

[0103] 1. The laser generating device, attosecond pulse laser generating and detecting device and measuring method of the present invention can use the central wavelength 860nm, 2170nm few-cycle high-energy femtosecond pulse laser or the coherent synthesis light field of the two lasers to react with rare gas to generate high-energy, high-photon energy, wide-spectrum short-pulse attosecond pulses, measure the time domain characteristics of attosecond pulses through time-delay locked pump-probe experiments, and measure the attosecond pulse spectrum with a flat-field grating spectrometer. The generated attosecond pulses can also be used to excite the electron dynamics inside the material, and the transient absorption spectrum of the material can be measured with a spectrometer, thereby studying the electron dynamics process inside the material.

[0104] 2. The present invention is a multifunctional device integrating attosecond pulse generation, measurement and application. It has the advantages of high femtosecond pulse laser energy, short pulse width, dual wavelength, high attosecond pulse energy, high photon energy, wide spectrum, high time resolution accuracy, high stability, etc. It can be widely used in the study of atomic inner shell ionization delay, Auger effect, electron correlation, Fano resonance, etc., and has good application prospects and commercial value.

[0105] Although the present invention has been described to a certain extent, it is obvious that appropriate changes in various conditions can be made without departing from the spirit and scope of the present invention. It is understood that the present invention is not limited to the embodiments described, but belongs to the scope of the claims, which includes equivalent replacements of each factor described.

Claims

1. A pulse laser generating device, characterized in that: The pulse laser generating device comprises: an oscillator, a pump source, a stretcher, an amplifier and a compressor; wherein: The oscillator generates two output lasers, the first output laser enters the pump source for amplification and then is transmitted to the amplifier; the other output laser enters the stretcher for spectrum broadening and then enters the amplifier, and then the stretched laser is amplified by the pump light output by the pump source, and then enters the compressor for pulse width compression, thereby obtaining the pulse laser; Preferably, the pump source is a picosecond pump source.

2. The pulse laser generating device according to claim 1, characterized in that: The number of the stretchers and amplifiers is 2, and the other output laser is divided into two paths and enters different stretchers for spectrum broadening and then enters different amplifiers for amplification; Preferably, the two stretchers have a stretching range of 1580-2450 nm and 680-1060 nm, more preferably 1800-2350 nm and 720-1050 nm, and most preferably 2000-2200 nm and 800-900 nm; and / or Preferably, the amplification ranges of the two amplifiers are 1580-2450 nm and 680-1060 nm, more preferably 1800-2350 nm and 720-1050 nm, and most preferably 2000-2200 nm and 800-900 nm.

3. The pulse laser generating device according to claim 1 or 2, characterized in that: The wavelengths of the pulsed laser are 680-1080 nm and 1580-2450 nm, preferably 720-1050 nm and 1800-2350 nm, more preferably 800-900 nm and 2000-2200 nm; The energy of the pulse laser is 1 to 7 mJ, preferably 5 to 7 mJ, more preferably 6 to 7 mJ; and / or The pulse width of the pulse laser is 5-11.5 fs and 18-40 fs, preferably 7-8 fs and 20-30 fs, and most preferably 7 fs and 25 fs.

4. An attosecond pulse laser generation and detection device, characterized in that: The attosecond pulse laser generation and detection device comprises: The pulse laser generating device according to any one of claims 1 to 3, and A vacuum chamber and the following components arranged inside the vacuum chamber: a pump detection device, a detection gas target, a time-of-flight spectrometer, a detection tire mirror and a spectrometer; Wherein, the femtosecond pulse laser generated by the pulse laser generating device according to any one of claims 1 to 3 passes through the pump-detection device, and generates attosecond pulse laser in the pump-detection device, and the attosecond pulse laser passes through the detection gas target, the time-of-flight spectrometer, the detection tire mirror and the spectrometer in sequence, wherein the electrons obtained by the attosecond pulse laser ionizing the gas of the detection gas target enter the time-of-flight spectrometer; Preferably, the time-of-flight spectrometer is located next to the detection gas target.

5. The attosecond pulse laser generation and detection device according to claim 4, characterized in that: The pump detection device comprises: a beam splitter, a pump light focusing system, a gas target, a metal film, a pump light tire mirror, a delay system, a detection light focusing system and a beam combining mirror; wherein, The femtosecond pulse laser is divided into pump light and detection light by a beam splitter. The pump light is loosely focused by a pump light focusing system to generate high-order harmonics in a gas target, and then passes through the metal film to obtain attosecond pulse laser, which then passes through a pump light tire mirror to reach a beam combining mirror. The detection light passes through a delay system and the detection light focusing system in sequence, and is combined with the attosecond pulse laser that reaches the beam combining mirror and converges to the detection gas target. Preferably, the laser detection device further comprises a solid target, and the solid target is located between the tire detection mirror and the spectrometer.

6. The attosecond pulse laser generating and detecting device according to claim 5, characterized in that: The pump light focusing system and the detection light focusing system are both selected from one or more of the following mirror systems: spherical mirrors, tire mirrors, parabolic mirrors, ellipsoidal mirrors, cylindrical mirrors, preferably spherical mirrors and / or parabolic mirrors, most preferably spherical mirrors; The focal spot diameters of the pump light focusing system and the detection light focusing system are less than 1 mm, preferably 0.2 to 0.5 mm, and more preferably 0.25 to 0.3 mm; The gas of the pump light gas target and the detection gas target is a rare gas, preferably selected from one or more of the following: helium, neon, argon, krypton, xenon, more preferably selected from one or more of the following: neon, argon, krypton, xenon, further preferably selected from one or more of the following: neon, argon, krypton; The generating gas target and the detecting gas target are a gas pool and / or a gas jet; The metal film is selected from one or more of the following: Al, Zr, Ti, Zn, Mo, Sn, preferably selected from one or more of the following: Al, Zr, Ti, Zn, more preferably Al and / or Zr; The beam combiner is selected from one or more of the following: a perforated beam combiner, a polarization beam combiner, a wavelength beam combiner, and the most preferred one is a perforated beam combiner; and / or The time-delay system comprises: a time-delay reflector, a time-delay vacuum electric translation stage and a time-delay piezoelectric translation stage. The time-delay reflector is preferably located on the time-delay vacuum electric translation stage and the time-delay piezoelectric translation stage.

7. The attosecond pulse laser generation and detection device according to any one of claims 4 to 6, characterized in that: The spectrometer comprises: a slit, a grating, a grating electric translation stage, a spectrometer electric turntable, a microchannel plate for converting photon signals into electrical signals, a fluorescent screen for converting electrical signals into fluorescent signals, and a camera for collecting fluorescent signals on the fluorescent screen; wherein, The wavelength range of the grating is 20-80 nm or 5-20 nm; and / or The camera is a CCD camera.

8. The attosecond pulse laser generation and detection device according to any one of claims 4 to 7, characterized in that: The attosecond pulse laser generation and detection device also includes: a laser source and a locking feedback system; wherein, The laser source is a continuous laser, and its wavelength is preferably 500-638 nm, more preferably 500-550 nm, and most preferably 532 nm; the laser source preferably passes through the pump-detection device to reach the locking feedback system; The locking feedback system is located after the beam combiner; and / or The laser source enters the pump-detection device through a beam splitter, spatially overlaps at the locking feedback system to generate interference fringes, and together with the time-delay voltage level shifting stage, forms a feedback locking system.

9. A method for measuring attosecond pulse spectrum, characterized in that: The measurement method comprises using an attosecond pulse laser generation and detection device as described in any one of claims 4 to 8; Preferably, the method for measuring the attosecond pulse spectrum includes: the pulse laser generating device emits a femtosecond pulse laser, and after passing through the pump detection device, the combined attosecond pulse laser and the detection light are converged to the detection gas target to ionize the gas to obtain electrons, a time-of-flight spectrometer measures the flight time of the electrons, and detects the time width of the attosecond pulse laser, and when the attosecond pulse laser passes through the detection tire mirror and reaches the spectrometer without passing through the solid target, the attosecond pulse spectrum is detected.

10. A method for measuring transient absorption spectrum, characterized in that: The method for measuring transient absorption spectra comprises using an attosecond pulse laser generating and detecting device as described in any one of claims 4 to 8; Preferably, the method for measuring the transient absorption spectrum includes: the pulse laser generating device emits a femtosecond pulse laser, and after passing through the pump detection device, the generated attosecond pulse laser and the detection light are converged to the detection gas target to achieve time and space overlap, and then incident on the solid target through the detection tire mirror, and then the electron dynamics inside the solid target are stimulated to reach the spectrometer, and the transient absorption spectrum of the solid material in the solid target is measured by the spectrometer.

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