Method for generating high-order mode relativistic vortex laser based on axial focusing pinhole plate

Abstract

The invention relates to a method for generating a high-order mode relativistic vortex laser based on an axial focusing pinhole plate, and the method comprises the steps: preparing an axial focusing spiral pinhole plate which is provided with a plurality of rows of pinhole groups which are regularly arranged in the circumferential direction of a plate body of the axial focusing spiral pinhole plate, and each pinhole group comprises a plurality of pinholes which are arranged in a spiral manner; a beam of Gaussian laser with relativistic intensity is adopted to irradiate the axial focusing spiral pinhole plate, and based on pinholes in the axial focusing spiral pinhole plate, the optical paths of laser transmitted by different pinholes to an optical axis are different, and angular phase difference is introduced for the transmitted Gaussian laser, so that vortex laser is formed in a focusing area. Vortex laser can be effectively generated by adopting the axial focusing spiral pinhole plate, the optical path difference of transmission laser is adjusted by adjusting the arrangement mode of pinholes in the axial focusing spiral pinhole plate, and then the mode that corresponding vortex laser is generated in a focusing area enables the scheme to be more flexible and lower in cost.

Description

Technical Field

[0001] The invention relates to the field of laser and plasma technology, and in particular to a method for generating high-order mode relativistic vortex laser based on an axial focusing pinhole plate. Background Art

[0002] Vortex light has attracted extensive attention due to its unique properties such as carrying orbital angular momentum, phase singularities and hollow intensity distribution. These remarkable properties have led to the extensive research and application of vortex lasers in many fields, from optical tweezers, quantum entanglement and communications to optical manufacturing and imaging. In the past decade, due to its outstanding prospects, the study of relativistic vortex lasers and their interaction with plasma has developed rapidly. Thanks to its ultra-high intensity and spiral electromagnetic field, relativistic vortex lasers are regarded as excellent tools for manipulating relativistic charged particle beams, emitting photon beams with orbital angular momentum, and exploring the angular momentum transfer of particles and electromagnetic fields under high energy, momentum and angular momentum density. Despite a large number of theoretical and numerical studies, experimental research on the interaction between relativistic vortex lasers and plasmas is relatively lagging. This is mainly due to the limited damage threshold of solid optical materials, which makes it a challenging task to generate high-quality relativistic vortex lasers in experiments.

[0003] To overcome this obstacle, researchers have made significant efforts in theoretical, numerical and experimental studies. Numerous theoretical or numerical studies have proposed various plasma-based schemes to generate relativistic vortex lasers. However, it is worth noting that most of these schemes focus on generating low-order modes of vortex lasers ( ), while the generation of higher-order relativistic vortex lasers is still relatively unstudied. Using off-axis helical phase mirrors, the researchers were able to generate lasers with intensities up to about , the main mode is However, the generation of high-order mode relativistic vortex lasers is still an area to be explored. Therefore, exploring a feasible scheme to generate high-quality high-order mode relativistic vortex lasers is of great value for the generation of high angular momentum relativistic particle beams or ultra-strong magnetic fields and the study of the interaction between extended relativistic vortex lasers and plasmas. Summary of the invention

[0004] The object of the present invention is to provide a method for generating high-order mode relativistic vortex laser based on an axial focusing pinhole plate.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a method for generating a high-order mode relativistic vortex laser based on an axial focusing pinhole plate, comprising the following steps: S1. preparing an axial focusing spiral pinhole plate, wherein the axial focusing spiral pinhole plate is provided with a plurality of pinhole groups regularly arranged along the circumference of the plate body, and each pinhole group includes a plurality of pinholes arranged along a spiral; S2. A beam of Gaussian laser of relativistic intensity is used to irradiate the axially focusing spiral pinhole plate, and based on the pinholes on the axially focusing spiral pinhole plate, the optical path lengths of lasers transmitted through different pinholes to reach the optical axis are different, thereby introducing an angular phase difference into the transmitted Gaussian laser to form a vortex laser in the focusing area.

[0006] According to one aspect of the present invention, in step S1, in the step of preparing an axial focusing spiral pinhole plate, the angular position and radial position of each pinhole on the axial focusing spiral pinhole plate are expressed as:

[0007] in, For the The angular position of the pinholes, For the The radial position of the pinholes, For the The focal length of a pinhole is expressed as: , and the focal length range of the pinhole is the minimum focal length To maximum focal length , the focal depth is ; is the number of pinholes; is the distance from the first pinhole in each pinhole group to the center of the axial focusing spiral pinhole plate, is the topological charge of the axially focusing spiral pinhole plate, and its value is a positive integer, is the wavelength of the incident laser.

[0008] According to one aspect of the present invention, the minimum focal length of the pinhole on the axial focusing spiral pinhole plate is It is expressed as: ; The maximum focal length of the pinhole on the axial focusing spiral pinhole plate It is expressed as: .

[0009] According to one aspect of the present invention, on the axial focusing spiral pinhole plate, each row of pinhole groups is arranged in a right-hand spiral manner; The pinhole closest to the center of the axial focusing spiral pinhole plate in each column of pinhole groups is the first pinhole, and the distance from the first pinhole to the center of the axial focusing spiral pinhole plate is The value range of is: .

[0010] According to one aspect of the present invention, the radius of the pinhole on the axial focusing spiral pinhole plate is satisfy: .

[0011] According to one aspect of the present invention, the axial focusing spiral pinhole plate is made of fully ionized carbon ion and hydrogen ion target materials, and the density ratio of carbon ions to hydrogen ions is 1:4.

[0012] According to one aspect of the present invention, the thickness of the axial focusing spiral pinhole plate is satisfy: .

[0013] According to one aspect of the present invention, in step S2, a beam of relativistic intensity Gaussian laser light is used which has a Gaussian intensity distribution, and its peak intensity is located at the optical axis.

[0014] According to one aspect of the present invention, in step S2, the intensity of a beam of relativistic intensity Gaussian laser used is .

[0015] According to one aspect of the present invention, the axial focusing spiral pinhole plate is manufactured by electron beam etching.

[0016] According to one scheme of the present invention, the present invention adopts an axially focusing spiral pinhole plate to effectively generate a vortex laser, and the arrangement of the pinholes on the axially focusing spiral pinhole plate is adjusted to adjust the optical path difference of the transmitted laser and thus generate a corresponding vortex laser in the focusing area, making this scheme more flexible and lower in cost.

[0017] According to one embodiment of the present invention, the present invention can generate a main mode by adjusting the arrangement of the pinholes on the axial focusing spiral pinhole plate. Vortex laser, achieving intensity greater than The main mode ratio is maintained at more than 60%. In addition, the axially focused spiral pinhole plate can adjust the topological charge of the vortex laser and amplify the intensity of the output vortex laser by more than four times. This shows that the axially focused spiral pinhole plate has significant potential in generating high-order mode vortex lasers and manipulating relativistic laser angular momentum.

[0018] According to one scheme of the present invention, the present invention provides a feasible method for generating ultra-strong high-order mode vortex laser by using an axially focused spiral pinhole plate, which can expand the research scope of the interaction between relativistic vortex laser and plasma and is of great significance to promoting research in this field. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a block diagram schematically showing the steps of a method for generating a high-order mode relativistic vortex laser based on an axial focusing pinhole plate according to an embodiment of the present invention; Figure 2 is a principle diagram schematically showing a method for generating a high-order mode relativistic vortex laser based on an axially focusing pinhole plate according to an embodiment of the present invention; Figure 3 is a structural diagram schematically showing an axial focusing spiral pinhole plate according to an embodiment of the present invention; Figure 4 is a diagram schematically showing the simulation results of the simulation box in Example 1; Figure 5 is a schematic diagram showing the simulation box in Example 1 and of The transverse electric field is shown on the plane And the simulation results of its phase, where (a) represents The transverse electric field at Simulation results, (b) represents The transverse electric field at Simulation results, (c) represents The phase simulation results at (d) are Phase simulation results at ; Figure 6 is a schematic diagram showing the simulation box in Example 1 and of The transverse electric field is shown on the plane Theoretical results of the phase, where (a) represents The transverse electric field at Theoretical results, (b) represents The transverse electric field at Theoretical results, (c) represents The phase theory result at , (d) represents The phase theory results at ; Figure 7 is a diagram schematically showing the intensity, mode spectrum and angular momentum, energy conversion efficiency and average photon angular momentum of the output vortex laser in Example 1, wherein (a) represents The intensity of the output vortex laser is The distribution of the yz plane at (b) The output vortex laser is (c) shows the evolution of the angular momentum of the output vortex laser and the energy conversion efficiency from the incident laser to the output vortex laser; (d) shows the evolution of the average angular momentum of the photons of the output vortex laser; Figure 8 is a schematic diagram showing the topological charge of the axial focusing spiral pinhole plate in Example 1. The simulation results in the simulation box when the value is set to 5, where (a) shows the structure of the axially focused spiral pinhole plate, and (b) shows the electric field of the output vortex laser. exist Department The distribution diagram of the output vortex laser is shown in (c). The phase of Department The distribution diagram of the output vortex laser is shown in (d). exist Department Mode spectrum distribution diagram when ; Fig. 9 is a schematic diagram showing the topological charge of the axial focusing spiral pinhole plate in Example 1. The simulation results in the simulation box when the value is set to 6, where (a) shows the structure of the axially focused spiral pinhole plate and (b) shows the electric field of the output vortex laser. exist Department The distribution diagram of the output vortex laser is shown in (c). The phase of Department The distribution diagram of the output vortex laser is shown in (d). exist Department Mode spectrum distribution diagram when ; Fig.10 is a schematic diagram showing the topological charge of the axial focusing spiral pinhole plate in Example 1. When set to 4, the incident laser mode is The simulation results in the simulation box, where (a) shows the structure of the axially focused spiral pinhole plate, and (b) shows the electric field of the output vortex laser. exist Department The distribution diagram of the output vortex laser is shown in (c). The phase of Department The distribution diagram of the output vortex laser is shown in (d). exist Department Mode spectrum distribution diagram when ; Fig.11It is a schematic representation Fig.10 Output vortex laser electric field of a mid-axially focused spiral pinhole plate in a simulation box Three-dimensional isosurface distribution map of . DETAILED DESCRIPTION

[0020] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0021] Combination Figure 1 , Figure 2 and Figure 3 As shown, according to one embodiment of the present invention, a method for generating a high-order mode relativistic vortex laser based on an axially focused pinhole plate of the present invention comprises the following steps: S1. preparing an axial focusing spiral pinhole plate, wherein the axial focusing spiral pinhole plate is provided with a plurality of rows of pinhole groups regularly arranged along the circumference of the plate body, and each pinhole group includes a plurality of pinholes arranged along a spiral; S2. A beam of Gaussian laser of relativistic intensity is used to irradiate the axially focused spiral pinhole plate. Based on the pinholes on the axially focused spiral pinhole plate, the optical path lengths of the lasers transmitted through different pinholes to reach the optical axis are different, and an angular phase difference is introduced into the transmitted Gaussian laser to form a vortex laser in the focusing area.

[0022] like Figure 2 As shown, according to one embodiment of the present invention, in step S1, in the step of preparing an axial focusing spiral pinhole plate, on the axial focusing spiral pinhole plate, multiple rows of hole groups are arranged at equal intervals along the circumference of the plate body to achieve a regular arrangement of the pinhole groups. In this embodiment, each pinhole group includes a plurality of pinholes arranged along a spiral, wherein the hand direction of the pinholes of each pinhole group along the spiral arrangement is consistent, thereby, on the axial focusing spiral pinhole plate, the pinholes are arranged in a spiral radiating form from the center to the surroundings. In this embodiment, the pinholes penetrate the body of the axial focusing spiral pinhole plate along the axial direction of the axial focusing spiral pinhole plate.

[0023] In this embodiment, the axial focusing spiral pinhole plate can be made of a regular plate, for example, a square plate, a circular plate, etc.

[0024] Through the above-mentioned arrangement, the present invention arranges spirally arranged pinholes on the axial focusing spiral pinhole plate, so that when a beam of Gaussian laser of relativistic intensity is irradiated onto the axial focusing spiral pinhole plate, the optical path lengths of lasers transmitted by different pinholes to reach the optical axis are different, thereby introducing an angular phase difference for the transmitted laser, thereby forming a vortex laser in the focusing area, that is, realizing the modulation of the seed laser into the vortex laser in the focusing volume.

[0025] like Figure 2As shown, according to one embodiment of the present invention, in step S1, in the step of preparing the axial focusing spiral pinhole plate, the angular position and radial position of each pinhole on the axial focusing spiral pinhole plate are expressed as:

[0026] in, For the The angular position of the pinholes, For the The radial position of the pinholes, For the The focal length of a pinhole is expressed as: , and the focal length range of the pinhole is the minimum focal length To maximum focal length , the focal depth is ; is the number of pinholes; is the distance from the first pinhole in each spiral pinhole arrangement to the center of the axial focusing spiral pinhole plate, is the topological charge of the axially focusing spiral pinhole plate, and its value is a positive integer, is the wavelength of the incident laser.

[0027] According to one embodiment of the present invention, the minimum focal length of the pinhole on the axial focusing spiral pinhole plate is It is expressed as: ; Furthermore, the maximum focal length of the pinhole on the axial focusing spiral pinhole plate It is expressed as: .

[0028] Through the above arrangement, it is effectively ensured that the vortex laser generated by the present invention has a wide focusing range, making it more widely applicable and further ensuring its convenience of use.

[0029] According to an embodiment of the present invention, on the axial focusing spiral pinhole plate, each row of pinhole groups is arranged in a right-hand spiral manner; The pinhole closest to the center of the axial focusing spiral pinhole plate in each column of pinhole groups is the first pinhole, and the distance from the first pinhole to the center of the axial focusing spiral pinhole plate is The value range of is: .

[0030] Through the above arrangement, the present scheme can more advantageously generate a high-order mode vortex laser in the corresponding focusing area by arranging the first pinhole in each column of pinhole groups with a spacing from the center of the axial focusing spiral pinhole plate, thereby making the generated vortex laser more stable.

[0031] According to one embodiment of the present invention, the radius of the pinhole on the axial focusing spiral pinhole plate is satisfy: .

[0032] Through the above settings, this solution sets the radius of the pinhole within the above range, so that the arranged pinhole can better match the input Gaussian laser, which is more advantageous for the solution to generate a high-order mode vortex laser in the corresponding focusing area, making the generated vortex laser more stable and accurate.

[0033] According to one embodiment of the present invention, the axial focusing spiral pinhole plate is made of fully ionized carbon ion and hydrogen ion target materials, and the density ratio of carbon ions to hydrogen ions is 1:4.

[0034] Through the above arrangement, the present invention adopts an axial focusing spiral pinhole plate made of fully ionized carbon ion and hydrogen ion target materials with a density ratio of 1:4, which can enhance the interaction between laser and plasma, optimize the laser acceleration process, promote the generation of high-order mode vortex laser, and improve the propagation characteristics of the laser beam; wherein, through the above-mentioned axial focusing spiral pinhole plate, it can form a Gaussian laser that better matches the input, which can significantly enhance the nonlinear effect of the laser. And the focusing ability can be significantly improved by the set density ratio.

[0035] According to one embodiment of the present invention, the thickness of the axial focusing spiral pinhole plate is satisfy: .

[0036] Through the above arrangement, the present solution sets the thickness of the axially focusing spiral pinhole plate within the above range, which is more advantageous for the present solution to generate a high-order mode of vortex laser in the corresponding focusing area, making the generated vortex laser more stable and effective.

[0037] According to an embodiment of the present invention, in step S2, a beam of relativistic intensity Gaussian laser light used has a Gaussian intensity distribution, and its peak intensity is located at the optical axis.

[0038] The Gaussian laser set up as above is more compatible with the corresponding pinhole setting mode, making the generation of high-order mode vortex laser more reliable and beneficial.

[0039] According to one embodiment of the present invention, in step S2, the intensity of a beam of relativistic intensity Gaussian laser used is .

[0040] Through the above arrangement, the present invention can more effectively adapt to the input of high-intensity laser and can also provide more favorable conditions for realizing high-intensity vortex laser.

[0041] According to one embodiment of the present invention, the axial focusing spiral pinhole plate is manufactured by electron beam etching.

[0042] In order to further illustrate this scheme, further examples are given to illustrate this scheme.

[0043] Example 1 Specifically, the 3D-PIC simulation using the relativistic electromagnetic code EPOCH was demonstrated. In this embodiment, the grid size of the simulation box is ,Therefore, the grid is set to 2000×800×800, and there are 9 macro particles in each grid.

[0044] Furthermore, the dimensionless laser electric field amplitude of the linearly polarized Gaussian laser pulse is , which is incident from the left side of the simulation box; where, and are the peak amplitude of the laser electric field and the laser focus spot size, respectively; is the laser wavelength, where is the laser period, is the laser frequency; , and are the unit charge, the mass of the electron and the speed of light in vacuum, is the basis vector of the electric field in the y direction of the electromagnetic field, Get the radial coordinate for the cylindrical coordinate system.

[0045] Furthermore, the initial position of the axial focusing spiral pinhole plate is in the simulation box The thickness of the axial focusing spiral pinhole plate is ; Among them, the focal length range of the pinhole on the axial focusing spiral pinhole plate can be set at arrive Thus, the initial position of the pinhole in the simulation box is set based on the axial focusing spiral pinhole plate so that its focal length ranges from Start to Finish.

[0046] In this embodiment, the distance between the first pinhole in each column of pinhole groups and the center of the axial focusing spiral pinhole plate is , the radius of each pinhole is , the number of pinholes is , the topological charge of the axially focusing spiral pinhole plate .

[0047] Furthermore, on the axial focusing spiral pinhole plate, the pinholes in each column of the pinhole group are arranged in a right-handed spiral.

[0048] Furthermore, the axial focusing spiral pinhole plate is made of fully ionized carbon ion and hydrogen ion target materials, and its composition is composed of fully ionized carbon ions and hydrogen ions with a density ratio of 1:4; wherein, electrons, protons ( ) and carbon ions ( ) has a corresponding density of , and .

[0049] Furthermore, the axially focused spiral pinhole plate is manufactured by electron beam etching.

[0050] Through the above-mentioned axial focusing spiral pinhole plate, when the incident seed laser (i.e., a beam of Gaussian laser of relativistic intensity) irradiates the axial focusing spiral pinhole plate, only a part of the laser can pass through the pinhole area. Since the optical path difference of the laser passing through the pinholes at different positions when reaching the focal volume is different, the axial focusing spiral pinhole plate can modulate the seed laser into a vortex laser in the focal volume.

[0051] Combination Figure 4 , Figure 5 and Figure 6 As shown, it shows The transverse electric field of the output laser The three-dimensional isosurface of the laser output shows a significant spiral spatial distribution. The characteristics of and of The transverse electric field is shown on the plane and its phase distribution. It should be noted that, in order to improve the performance of the simulation process and reduce memory usage, the EPOCH code, like most particle codes, uses real numbers to represent the electromagnetic field data. However, the electromagnetic field information from the numerical simulation output can be reconstructed in the form of complex spectral coefficients. To this end, the phase of the laser electromagnetic field can be expressed as:

[0052] in, and denote Fourier transform and inverse Fourier transform respectively, represents the imaginary part, represents the real part, represents the frequency of the laser, represents the wave vector component of the laser, represents the mode of the laser wave vector, Represents the laser wave vector Quantity, Represents the laser wave vector Quantity, The laser magnetic field Quantity, The laser magnetic field Quantity.

[0053] like Figure 5 (a) and Figure 5 As shown in (b), the emitted laser electric field presents a petal-shaped periodic distribution around the optical axis. The phase distribution shows the transverse electric field of the laser It undergoes four cycles around the optical axis ([ ]). This shows that the topological charge of the dominant mode of the output laser is , which is consistent with the topological charge setting of the axially focusing spiral pinhole plate.

[0054] Furthermore, to evaluate the performance of the axially focused spiral pinhole plate, we used the Fresnel-Kirchhoff diffraction formula to calculate the electric field and phase distribution of the output laser, which are expressed as follows:

[0055] in, represents an imaginary number; represents the electric field of the incident Gaussian laser; represents the transmittance of the axially focused spiral pinhole plate; represents the tilt factor and is expressed as: ; Indicates representative point To point The radius vector and Point Normal The angle of Indicate point To point spatial distance.

[0056] Based on this, the theoretical calculation and simulation results show excellent consistency in the electric field and phase distribution of the output laser. In addition, the focal spot size of the output vortex laser is Reduced to about , which is due to the focusing ability of the axially focused spiral pinhole plate. However, since the radial intensity of the Gaussian laser decreases along the optical axis, the focused intensity enhancement of the output laser is not obvious and is almost consistent with the incident laser. In the area corresponding to the target pinhole area of ​​the axially focused spiral pinhole plate, the intensity has dropped below the maximum value.

[0057] Based on the above simulation process, select the output in the simulation box Department The transverse electric field slices and calculate their mode spectra. As we all know, any laser field can be decomposed into a weighted superposition of Laguerre-Gaussian (LG) modes, and the weight of the LG mode is defined as:

[0058] in, The electric field slice representing the output laser; yes Electric field slicing of mode lasers; Represent the three coordinates of the cylindrical coordinate system.

[0059] Mode in cylindrical coordinates is defined as: , in, represents a constant, Represents radial index and azimuth index The generalized Laguerre polynomial of , in the calculation, Set to 0, is considered a variable, represents the wave vector of the laser.

[0060] Figure 7 (b) shows that the dominant mode of the output vortex laser is , with a weight of 64.54%, Figure 4 , Figure 5 and Figure 6 In addition, the total angular momentum of the output vortex laser, the energy conversion efficiency from the incident laser to the output laser, and the focal volume ( ). The angular momentum and energy of the laser pulse (i.e., the Gaussian laser output by the light source) can be expressed as and ,in, represents the vacuum permeability, represents the vacuum dielectric constant, Represents the radial distance in space, represents the electric field of the laser, represents the magnetic field of the laser, represents the volume differential in the integral, are the angular momentum of the laser pulse. Quantity, Quantity, component. The average angular momentum of the laser photon can be written as ,in, and represents the spin and orbital angular momentum of the photon, represents the reduced Planck constant. Given that the angular momentum carried by the laser is mainly along its propagation axis, the angular momentum mainly corresponds to .like Figure 7 As shown in (c), when the laser gradually enters the focal volume, it transforms into a vortex laser and the angular momentum increases to a maximum value. exist As the laser gradually leaves the focal volume, its vortex phase is gradually lost and the angular momentum begins to decrease. The evolution of the energy conversion efficiency of the output vortex laser is consistent with the angular momentum, reaching a maximum value of 5.4%. Figure 7 (d) shows the evolution of the average angular momentum of the output laser photons. As the laser enters the focusing region, the average angular momentum carried by the photons increases rapidly. Reaching the maximum value When the output laser is still in the focus area, the average angular momentum of its photons can be maintained for more than This indicates that the vortex phase of the output laser in the focusing region can be well maintained.

[0061] Furthermore, when the topological charge of the axially focusing spiral pinhole plate or the incident laser is changed, the dominant mode of the output laser can also be adjusted by this scheme. Change to 5 and 6 respectively. Combine Figure 8 and Fig. 9 The cross-sectional structure, lateral distribution of electric field, phase distribution and their relationship of the axial focusing spiral pinhole plate in two cases are shown. Mode spectrum. Figure 8 and Fig. 9 As shown in The number of spiral arms (i.e., pinhole groups) formed by the change in the pinhole arrangement also changes accordingly. Accordingly, the electric field phase of the output laser also changes, and experiences 5 and 6 cycles around the optical axis. The dominant mode of the output laser becomes and , and the mode weights are 61.03% and 62.45% respectively.

[0062] In addition to the topological charge , the topological charge of the incident laser can also change the dominant mode of the output laser. In the simulation, consider the incident laser to be mode, while keeping other parameters unchanged. , the dominant mode of the output laser becomes , with a weight of 72.52%. This indicates that the topological charge of the dominant mode of the output laser is determined by the axially focused spiral pinhole plate and the incident laser, which can be expressed as In addition, the annular intensity distribution of the input laser causes its peak intensity to be located in the pinhole region of the axially focused spiral pinhole plate. This results in a better focusing effect of the output laser, with a maximum intensity of Although existing schemes have been able to generate dominant modes in the laboratory by using off-axis spiral phase mirrors , strength up to However, current theoretical calculations show that the use of off-axis spiral phase mirrors faces challenges in generating high-order mode vortex lasers due to the relatively low weight of the dominant mode. This suggests that this scheme can generate higher-intensity high-order vortex lasers with high mode purity, which may expand the scope of research on the interaction between relativistic vortex lasers and plasmas.

[0063] The above contents are merely examples of specific solutions of the present invention. For devices and structures not described in detail therein, it should be understood that they can be implemented by adopting general devices and general methods available in the art.

[0064] The above is only one solution of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for generating high-order mode relativistic vortex laser based on an axially focused pinhole plate, characterized in that: The following steps are involved: S1. preparing an axial focusing spiral pinhole plate, wherein the axial focusing spiral pinhole plate is provided with a plurality of pinhole groups regularly arranged along the circumference of the plate body, and each pinhole group includes a plurality of pinholes arranged along a spiral; S2. A beam of Gaussian laser of relativistic intensity is used to irradiate the axially focusing spiral pinhole plate, and based on the pinholes on the axially focusing spiral pinhole plate, the optical path lengths of lasers transmitted through different pinholes to reach the optical axis are different, thereby introducing an angular phase difference into the transmitted Gaussian laser to form a vortex laser in the focusing area.

2. The method according to claim 1, characterized in that In step S1, in the step of preparing the axial focusing spiral pinhole plate, the angular position and radial position of each pinhole on the axial focusing spiral pinhole plate are expressed as: in, For the The angular position of the pinholes, For the The radial position of the pinholes, For the The focal length of a pinhole is expressed as: , and the focal length range of the pinhole is the minimum focal length To maximum focal length , the focal depth is ; is the number of pinholes; is the distance from the first pinhole in each pinhole group to the center of the axial focusing spiral pinhole plate, is the topological charge of the axially focusing spiral pinhole plate, and its value is a positive integer, is the wavelength of the incident laser.

3. The method according to claim 2, characterized in that The minimum focal length of the pinhole on the axial focusing spiral pinhole plate It is expressed as: ； The maximum focal length of the pinhole on the axial focusing spiral pinhole plate It is expressed as: 。 4. The method according to claim 3, characterized in that On the axial focusing spiral pinhole plate, each row of pinhole groups is arranged in a right-hand spiral manner; The pinhole closest to the center of the axial focusing spiral pinhole plate in each column of pinhole groups is the first pinhole, and the distance from the first pinhole to the center of the axial focusing spiral pinhole plate is The value range of is: 。 5. The method according to claim 4, characterized in that The radius of the pinhole on the axial focusing spiral pinhole plate satisfy: 。 6. The method according to claim 5, characterized in that The axial focusing spiral pinhole plate is made of fully ionized carbon ion and hydrogen ion target materials, and the density ratio of carbon ions to hydrogen ions is 1:

4.

7. The method according to claim 6, characterized in that The thickness of the axial focusing spiral pinhole plate satisfy: 。 8. The method according to claim 7, characterized in that In step S2, a beam of relativistic intensity Gaussian laser light is used which has a Gaussian intensity distribution, and its peak intensity is located at the optical axis.

9. The method according to claim 8, characterized in that In step S2, the intensity of a Gaussian laser beam of relativistic intensity is .

10. The method according to claim 8, characterized in that The axial focusing spiral pinhole plate is manufactured by electron beam etching.

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