Method and device for realizing off-axis focusing of relativistic laser

Abstract

The present invention belongs to the field of laser and plasma technology, and provides a method and device for realizing relativistic laser off-axis focusing, wherein a beam of light is used to irradiate a plasma off-axis lens, and by setting the density distribution of the plasma off-axis lens, the phase velocity of the laser propagating in the plasma changes, thereby realizing off-axis focusing of the laser, and realizing arbitrary regulation of the focusing position. Further, based on the characteristics of off-axis focusing, a laser beam splitting array is proposed, and the generation of an axial magnetic field can be realized through this array.

Description

Technical Field

[0001] The invention belongs to the field of laser and plasma technology, and particularly relates to a method and a device for realizing relativistic laser off-axis focusing. Background Art

[0002] In recent decades, the field of laser technology has made significant progress. In the design and application of modern optical systems, there is an increasing demand for efficient, compact and low-distortion optical components. Although traditional axisymmetric lenses perform well in achieving high-quality imaging and beam control, their symmetry requirements for the optical axis limit the system's freedom, especially in space-constrained or complex optical path designs, which can easily lead to problems such as long optical paths and reduced efficiency. To overcome this limitation, off-axis lenses came into being. Off-axis lenses form an asymmetric structure by partially intercepting or redesigning the optical surface of a traditional lens. This structure can effectively avoid beam obstruction, reduce mutual interference between optical components, and significantly improve system performance in certain specific applications. For example, in the fields of lidar, free-space optical communications, and astronomical observations, off-axis lenses have attracted much attention due to their excellent off-axis imaging capabilities and low scattering characteristics. In addition, compared with traditional optical components, off-axis lenses can also reduce the size and weight of the system, which is particularly important for portable and aerospace applications.

[0003] The generation and manipulation of high-intensity laser pulses become increasingly difficult as the peak laser intensity increases due to the damage threshold of conventional solid-state optical components. To address this challenge, plasma-based optical components have been extensively studied, with damage thresholds several orders of magnitude higher than those of solid-state optical components. Over the past few decades, various advanced plasma optical components have been demonstrated to effectively modulate the temporal contrast, phase, polarization, pulse width, and intensity of relativistic laser pulses. In addition, the use of plasma to focus laser pulses as a means of modulation to increase laser intensity has recently gained considerable attention in the academic community. These include stimulated Raman scattering amplification, self-focusing laser amplification, conical target laser amplification, plasma lens-based laser amplification, and plasma-based multi-beam combination amplification. Previous studies have found that plasma-based multi-beam combination can achieve not only focusing effects but also the generation of strong axial magnetic fields. However, the development of such a magnetic field remains a major challenge, mainly because conventional linearly polarized laser beams cannot induce the required azimuthal current or equivalent angular momentum. In previous studies, a new scheme was proposed to generate an axial magnetic field by employing multiple laser beams with twisted propagation directions, which interact together with the plasma medium to induce the required magnetic field.

[0004] However, in the current research process, the generation of relativistic laser pulses still faces huge challenges. There is currently a lack of effective methods to achieve off-axis focusing at relativistic laser intensities, and it is still very difficult to generate multiple beams simultaneously. Summary of the invention

[0005] In view of the defects and shortcomings in the prior art, a method and device for realizing relativistic laser focusing are provided, in which a beam of light is used to irradiate a plasma off-axis lens, and the axial density distribution of the plasma off-axis lens is adjusted to change the phase velocity of the laser propagating in the plasma, thereby realizing laser focusing.

[0006] In order to solve the technical problems existing in the above-mentioned prior art, the technical solution adopted by the present invention is:

[0007] On the one hand, a method for realizing relativistic laser off-axis focusing is proposed, comprising:

[0008] Setting the incident laser and the focusing position of the incident laser after passing through the plasma off-axis lens, i.e., the focal position, wherein the focusing position is a position deviating from the central axis direction of the plasma off-axis lens, and the incident laser is a relativistic intensity laser;

[0009] Determining a density distribution of a plasma off-axis lens according to the focus position;

[0010] The incident laser is incident on the plasma off-axis lens having the density distribution, and the phase velocity of the incident laser propagating in the plasma off-axis lens changes, thereby achieving off-axis focusing of the incident laser at a set focusing position.

[0011] Further, determining the density distribution of the plasma off-axis lens according to the focus position includes:

[0012] For any point on the plasma off-axis lens, the plasma density Determined by the following formula:

[0013] ;

[0014] in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the vacuum dielectric constant, is the object light frequency. is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, hIt represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the point where the density of the plasma off-axis lens is the minimum to the focus. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ;

[0015] The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

[0016] Furthermore, the phase velocity of the incident laser at any point in the plasma off-axis lens is Will be based on Modulation is performed to achieve off-axis focusing of the incident laser at a set focusing position, where c is the speed of light.

[0017] Furthermore, the incident laser is a Gaussian laser pulse of linear polarization and relativistic intensity.

[0018] On the other hand, a device for realizing relativistic laser off-axis focusing is provided, comprising an incident laser generating device and a plasma off-axis lens;

[0019] The incident laser generating device outputs the incident laser and irradiates the incident laser onto a plasma off-axis lens having a set density distribution. The phase velocity of the incident laser propagating in the plasma off-axis lens changes, and the incident laser is off-axis focused at a set focus position. The focus position is a position deviating from the center axis direction of the plasma off-axis lens. The incident laser is a relativistic intensity laser. The density distribution of the plasma off-axis lens is determined according to the focus position, including: for any point on the plasma off-axis lens, its plasma density Determined by the following formula:

[0020] ;

[0021] in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the dielectric constant of vacuum, is the object light frequency. is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the point where the density of the plasma off-axis lens is the minimum to the focus. dis the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ;

[0022] The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

[0023] On the other hand, a method for realizing relativistic laser off-axis focusing is provided, comprising:

[0024] Determine the incident laser and the incident laser after passing through the plasma off-axis lens array n The incident laser is a relativistic intensity laser, and the plasma off-axis lens array is composed of n The plasma off-axis lenses are arranged in an array. The incident laser is incident on the plasma off-axis lens array. n The plasma off-axis lenses correspond to n A focusing position, and the focusing position corresponding to each plasma off-axis lens is a position deviated from the central axis direction thereof;

[0025] Determining the density distribution of each plasma off-axis lens in the plasma off-axis lens array according to different focusing positions corresponding to each plasma off-axis lens in the plasma off-axis lens array;

[0026] The incident laser is incident on the plasma off-axis lens array, and the phase velocity of the incident laser propagating in each plasma off-axis lens in the plasma off-axis lens array changes, and the incident laser is divided into n beams of laser light with twisted propagation directions, and each beam of laser light output by the splitting is focused to a corresponding focusing position respectively.

[0027] On the other hand, a device for realizing relativistic laser off-axis focusing is provided, comprising an incident laser generating device and a plasma off-axis lens array;

[0028] The incident laser generating device outputs the incident laser and irradiates the incident laser onto the plasma off-axis lens array with a set density distribution. The incident laser is a relativistic intensity laser. The plasma off-axis lens array is composed of n The plasma off-axis lenses are arranged in an array. The incident laser is incident on the plasma off-axis lens array. n The plasma off-axis lenses correspond to n A focusing position, and the focusing position corresponding to each plasma off-axis lens is a position deviated from the central axis direction thereof;

[0029] An incident laser is incident on the plasma off-axis lens array, and the phase velocity of the incident laser propagating in each plasma off-axis lens in the plasma off-axis lens array changes, and the incident laser is divided into n beams of laser light with twisted propagation directions, and each beam of laser light outputted by the beam splitting is focused to a corresponding focusing position, wherein the density distribution of each plasma off-axis lens in the plasma off-axis lens array is determined according to the different focusing positions corresponding to each plasma off-axis lens in the plasma off-axis lens array, including: for any point on any plasma off-axis lens in the plasma off-axis lens array, its plasma density Determined by the following formula:

[0030] ;

[0031] in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the vacuum dielectric constant, is the object light frequency. is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the focus at the minimum value of the plasma off-axis lens density. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ;

[0032] The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

[0033] The present invention proposes an off-axis plasma lens (OAFPL), which manipulates the phase velocity of laser pulses transmitted in plasma by modulating the density gradient of the plasma, thereby generating high-intensity tightly focused lasers and achieving arbitrary control of the focus position. Based on the off-axis focusing characteristics of the plasma off-axis lens (OAFPL), a plasma off-axis lens array capable of beam splitting is also designed. The plasma off-axis lens array consists of n The plasma off-axis lenses are arranged in an array. The incident laser is incident on the plasma off-axis lens array. n The plasma off-axis lenses correspond to nThe focal positions of each plasma off-axis lens are all deviated from the central axis direction, which can divide the incident laser into n Beam, plasma off-axis lens array output n Laser beam correspondence n focusing positions. Further, using a plasma off-axis lens array with four plasma off-axis lenses, the incident laser can be split into four beams, and the laser beams form a spiral path in a plane perpendicular to the propagation direction, imparting orbital angular momentum (OAM) to the photons. During the interaction between the laser and the plasma, the orbital angular momentum (OAM) is transferred to the electrons in the plasma, resulting in the generation of azimuthal currents, which subsequently generate axial magnetic fields. The present invention opens up a new venue with potential applications in the interaction of strong lasers with plasmas in high energy density physics, laboratory astrophysics and nonlinear optics. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0035] Figure 1 A schematic diagram of a method for realizing off-axis focusing of a relativistic laser in an embodiment;

[0036] Figure 2 : is a density distribution and phase distribution diagram of a plasma off-axis lens in one embodiment, wherein Figure 2 (a) is the density distribution diagram of the plasma off-axis lens. Figure 2 (b) is the phase distribution diagram of the plasma off-axis lens;

[0037] Figure 3 In one embodiment, the laser is focused through a plasma off-axis lens at ( x , z ) surface electric field distribution and Poynting vector distribution diagram, where Figure 3 (a) The laser is focused through the plasma off-axis lens at ( x , z ) surface electric field distribution, Figure 3 (b) The laser is focused through the plasma off-axis lens at ( x , z ) surface Poynting vector distribution map;

[0038] Figure 4 A plasma density distribution diagram in a plasma off-axis lens array according to an embodiment;

[0039] Figure 5 A schematic diagram of generating an axial magnetic field by a plasma off-axis lens array in one embodiment;

[0040] Figure 6 This is a comparative diagram of the effects of a comparative embodiment, wherein Figure 6 (a) is the axial magnetic field generated by the interaction between the laser and the plasma target after passing through the plasma off-axis lens array ( x , y ) Distribution diagram on the cross section; Figure 6 (b) is the axial magnetic field generated by the direct interaction of a Gaussian laser beam with the plasma target without passing through the plasma off-axis lens array. x , y ) distribution diagram on the cross section. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In one embodiment, a method for realizing relativistic laser off-axis focusing is provided, comprising:

[0043] Setting the incident laser and the focusing position of the incident laser after passing through the plasma off-axis lens, i.e., the focal position, wherein the focusing position is a position deviating from the central axis direction of the plasma off-axis lens, and the incident laser is a relativistic intensity laser;

[0044] Determining a density distribution of a plasma off-axis lens according to the focus position;

[0045] The incident laser is incident on the plasma off-axis lens having the density distribution, and the phase velocity of the incident laser propagating in the plasma off-axis lens changes, thereby achieving off-axis focusing of the incident laser at a set focusing position.

[0046] Wherein, determining the density distribution of the plasma off-axis lens according to the focusing position includes:

[0047] For any point on the plasma off-axis lens, the plasma density Determined by the following formula:

[0048] ;

[0049] in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the dielectric constant of vacuum, is the object light frequency. is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the point where the density of the plasma off-axis lens is the minimum to the focus. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ;

[0050] The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

[0051] Preferably, the incident laser is a linearly polarized Gaussian laser pulse of relativistic intensity.

[0052] When a Gaussian laser pulse of relativistic intensity irradiates a plasma with a density gradient change, the phase velocity of the laser propagating in the plasma changes. Specifically, the phase velocity of the incident laser propagating at any point in the plasma off-axis lens of the present invention is Will be based on Modulation is performed to achieve off-axis focusing of the incident laser at a set focusing position, where c is the speed of light.

[0053] The process of Gaussian laser pulse passing through the plasma off-axis lens follows the principle of equal optical path:

[0054] ;

[0055] Here d is the thickness of the plasma off-axis lens, and Represent the refractive index at any two points A and B on the plasma off-axis lens, and Represents the distance from point A and point B to the focal point. According to the refractive index formula , which allows for variations in the plasma density.

[0056] Figure 1 It is a schematic diagram of realizing relativistic laser off-axis focusing in one embodiment. After the incident laser passes through the plasma off-axis lens 1, its propagation direction changes significantly and deviates to the set focal position. Figure 1The key features of the proposed scheme and focused laser generation are demonstrated. The proposed method has been demonstrated using 3D-PIC simulations using the relativistic electromagnetic code EPOCH. In the simulation, the incident laser is a linearly polarized Gaussian laser pulse with a wavelength of 1 , the focal spot size is . Laser in x = 0, starting from the left boundary along the positive x The normalized amplitude of the electric field of the incident laser is .here, is the unit charge, is the electric field amplitude, is the mass of the electron, is the speed of light in a vacuum, is the laser frequency. The total duration of the incident laser pulse is 6 . Figure 2 : is a density distribution and phase distribution diagram of a plasma off-axis lens in one embodiment, wherein Figure 2 (a) is the density distribution diagram of the plasma off-axis lens, which is composed of fully ionized carbon ions, hydrogen ions and electrons. The radius of the plasma off-axis lens is set to R = 5 , the thickness is set to d = 3 , minimum density The plasma density distribution is: at the plasma off-axis lens (OAFPL) radius R = 5 μm The density gradient distribution is presented along the axial direction. The minimum value of the plasma off-axis lens (OAFPL) density is 0.1 The Off-Axis Plasma Lens (OAFPL) is located at x = 3 and x = 6 Between, the thickness is d =3 The simulation box is set to , the grid is set to , each grid is set with 6 macro particles. The density of the lightest known solid material can reach 0.16 kg / m 3 , corresponding to a fully ionized plasma density of 0.028 In contrast, the minimum density of the plasma off-axis lens of the present invention is 0.1 The unique density gradient structure of the off-axis plasma lens (OAFPL) can be efficiently manufactured using 3D printing technology. Figure 2 (b) is the phase distribution diagram of the plasma off-axis lens, and its phase distribution covers The incident laser can be focused by the plasma off-axis lens. Figure 1 At the specified position shown (25 , 0 , -6 ). According to the required focusing position, a plasma off-axis lens with a specific density distribution can be selected to achieve off-axis focusing at any focusing position.

[0057] Figure 3 In one embodiment, the laser is focused through a plasma off-axis lens at ( x , z ) surface electric field distribution and Poynting vector distribution diagram, where Figure 3 (a) The laser is focused through the plasma off-axis lens at ( x , z ) surface electric field distribution, Figure 3 (b) The laser is focused through the plasma off-axis lens at ( x , z ) surface; the Poynting vector can be calculated as S = E × B. After the incident laser passes through the OAFPL, x =10 To 20 The electric field is shown The distribution of Figure 3 (a) It can be observed that after passing through the off-axis plasma lens (OAFPL), the propagation direction of the laser is significantly deflected toward the focal position. Figure 3 The arrows in (b) indicate the distribution of the Poynting vector pointing to the focus. The distribution of the Poynting vector in the plane provides stronger evidence for the off-axis focusing capability of the plasma off-axis lens (OAFPL).

[0058] In one embodiment, a device for realizing relativistic laser off-axis focusing is provided, comprising an incident laser generating device and a plasma off-axis lens;

[0059] The incident laser generating device outputs the incident laser and irradiates the incident laser onto a plasma off-axis lens having a set density distribution. The phase velocity of the incident laser propagating in the plasma off-axis lens changes, and the incident laser is off-axis focused at a set focus position. The density distribution of the plasma off-axis lens is determined according to the focus position, including: for any point on the plasma off-axis lens, its plasma density Determined by the following formula:

[0060] ;

[0061] in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the vacuum dielectric constant, is the object light frequency. is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the focus at the minimum value of the plasma off-axis lens density. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ;

[0062] The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

[0063] In another embodiment, a method for realizing relativistic laser off-axis focusing is provided, comprising:

[0064] Determine the incident laser and the incident laser after passing through the plasma off-axis lens array n The focus positions are all positions deviating from the axial direction, the incident laser is a relativistic intensity laser, and the plasma off-axis lens array is composed of n The plasma off-axis lenses are arranged in an array. The incident laser is incident on the plasma off-axis lens array. n The plasma off-axis lenses correspond to n A focusing position, and the focusing position corresponding to each plasma off-axis lens is a position deviated from the central axis direction thereof;

[0065] Determining the density distribution of each plasma off-axis lens in the plasma off-axis lens array according to different focusing positions corresponding to each plasma off-axis lens in the plasma off-axis lens array;

[0066] The incident laser is incident on the plasma off-axis lens array, and the phase velocity of the incident laser propagating in each plasma off-axis lens in the plasma off-axis lens array changes, and the incident laser is divided into n beams of laser light with twisted propagation directions, and each beam of laser light output by the splitting is focused to a corresponding focusing position respectively.

[0067] Determining the density distribution of each plasma off-axis lens in the plasma off-axis lens array according to different focusing positions corresponding to each plasma off-axis lens in the plasma off-axis lens array includes:

[0068] For any point on any plasma off-axis lens in the plasma off-axis lens array, the plasma density Determined by the following formula:

[0069] ;

[0070] in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the dielectric constant of vacuum, is the object light frequency. is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the point where the density of the plasma off-axis lens is the minimum to the focus. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ;

[0071] The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

[0072] Furthermore, the incident laser is a Gaussian laser pulse of linear polarization and relativistic intensity.

[0073] Figure 4 FIG. 1 is a plasma density distribution diagram in a plasma off-axis lens array according to an embodiment of the present invention. Figure 5 FIG. 1 is a schematic diagram of generating an axial magnetic field by a plasma off-axis lens array in one embodiment, Figure 4 It can be seen that the plasma off-axis lens array 2 is composed of four plasma off-axis lenses with different focusing positions arranged in an array. The focusing positions of the four plasma off-axis lenses are (25 , 0 , -6 ), (25 , 0 , 6 ), (25 , 6 , 0 ), (25 , -6 , 0 ). The connection between the four plasma off-axis lenses uses a density of 15 The plasma is filled so that the incident laser cannot pass through here. Figure 5 The incident laser passes through Figure 4 The plasma off-axis lens array 2 shown in the figure generates an axial magnetic field. After passing through the plasma off-axis lens array 2, the incident laser is divided into four laser beams with twisted propagation directions. The split laser beams act on the plasma off-axis lens array 10 The plasma target 3 at the position of the plasma target 3 has a thickness of 5 , density is 0.5 , each beam converges at a different point on the plasma target. The laser beam forms a spiral path in a plane perpendicular to the propagation direction, imparting orbital angular momentum (OAM) to the photons. During the laser-plasma interaction, OAM is transferred to electrons in the plasma, leading to the generation of azimuthal currents, which subsequently generate an axial magnetic field. This mechanism follows the Biot-Savart law.

[0074] Figure 6 This is a comparative diagram of the effects of a comparative embodiment, wherein Figure 6 (a) is the axial magnetic field generated by the interaction between the laser and the plasma target after passing through the plasma off-axis lens array ( x , y ) Distribution diagram on the cross section; Figure 6 (b) is the axial magnetic field generated by a Gaussian laser beam that does not pass through the plasma off-axis lens array and directly interacts with the plasma target. x , y ) cross-section distribution diagram, used to compare Figure 6 (a) Perform a control. Figure 6 (a) shows the magnetic field generated by the interaction between the incident laser and the plasma target after passing through the plasma off-axis lens array ( x , y ) distribution in the plane ( ).from Figure 6 As can be seen in (a), the magnetic field is along x axis distribution, the magnetic field intensity can reach 200 T. To facilitate comparative analysis, the plasma off-axis lens array was removed in the control group, while all other parameters remained unchanged and simulated. Figure 6 (b) shows the axial magnetic field generated by the direct interaction between the Gaussian laser and the plasma target in the simulation. x , y ) cross section, it can be seen that the incident Gaussian laser directly interacts with the plasma target and does not generate an axial magnetic field.

[0075] In another embodiment, a device for realizing relativistic laser off-axis focusing is provided, comprising an incident laser generating device and a plasma off-axis lens array;

[0076] The incident laser generating device outputs the incident laser and irradiates the incident laser onto the plasma off-axis lens array with a set density distribution, the focusing positions are all positions deviating from the axial direction, the incident laser is a relativistic intensity laser, and the plasma off-axis lens array is composed of n The plasma off-axis lenses are arranged in an array. The incident laser is incident on the plasma off-axis lens array. n The plasma off-axis lenses correspond to n A focusing position, and the focusing position corresponding to each plasma off-axis lens is a position deviated from the central axis direction thereof;

[0077] An incident laser is incident on the plasma off-axis lens array, and the phase velocity of the incident laser propagating in each plasma off-axis lens in the plasma off-axis lens array changes, and the incident laser is divided into n beams of laser light with twisted propagation directions, and each beam of laser light outputted by the beam splitting is focused to a corresponding focusing position, wherein the density distribution of each plasma off-axis lens in the plasma off-axis lens array is determined according to the different focusing positions corresponding to each plasma off-axis lens in the plasma off-axis lens array, including: for any point on any plasma off-axis lens in the plasma off-axis lens array, its plasma density Determined by the following formula:

[0078] ;

[0079] in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the dielectric constant of vacuum, is the object light frequency. is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the point where the density of the plasma off-axis lens is the minimum to the focus. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ;

[0080] The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

[0081] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for realizing relativistic laser off-axis focusing, characterized in that: include: Setting the incident laser and the focusing position of the incident laser after passing through the plasma off-axis lens, i.e., the focal position, wherein the focusing position is a position deviating from the central axis direction of the plasma off-axis lens, and the incident laser is a relativistic intensity laser; Determining a density distribution of a plasma off-axis lens according to the focus position; The incident laser is incident on the plasma off-axis lens having the density distribution, and the phase velocity of the incident laser propagating in the plasma off-axis lens changes, thereby achieving off-axis focusing of the incident laser at a set focusing position.

2. The method for realizing relativistic laser off-axis focusing according to claim 1, characterized in that: Determining the density distribution of the plasma off-axis lens according to the focusing position includes: For any point on the plasma off-axis lens, the plasma density Determined by the following formula: in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the vacuum dielectric constant, is the object light frequency, is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the focus at the minimum value of the plasma off-axis lens density. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ; The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

3. The method for realizing relativistic laser off-axis focusing according to claim 2, characterized in that: The phase velocity of the incident laser propagating at any point in the plasma off-axis lens Will be based on Modulation is performed to achieve off-axis focusing of the incident laser at a set focusing position, where c is the speed of light.

4. The method for realizing relativistic laser off-axis focusing according to claim 2, characterized in that: The incident laser is a Gaussian laser pulse with linear polarization and relativistic intensity.

5. The method for realizing relativistic laser off-axis focusing according to claim 4, characterized in that: The plasma off-axis lens radius is R = 5 , the thickness of the plasma off-axis lens is d = 3 .

6. A device for realizing off-axis focusing of relativistic laser, characterized in that: It includes an incident laser generating device and a plasma off-axis lens; The incident laser generating device outputs the incident laser and irradiates the incident laser onto a plasma off-axis lens having a set density distribution. The phase velocity of the incident laser propagating in the plasma off-axis lens changes, and the incident laser is off-axis focused at a set focus position. The focus position is a position deviating from the center axis direction of the plasma off-axis lens. The incident laser is a relativistic intensity laser. The density distribution of the plasma off-axis lens is determined according to the focus position, including: for any point on the plasma off-axis lens, its plasma density Determined by the following formula: in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the vacuum dielectric constant, is the object light frequency, is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the focus at the minimum value of the plasma off-axis lens density. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ; The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

7. A method for realizing relativistic laser off-axis focusing, characterized in that: include: Determine the incident laser and the incident laser after passing through the plasma off-axis lens array n The incident laser is a relativistic intensity laser, and the plasma off-axis lens array is composed of n The plasma off-axis lenses are arranged in an array. The incident laser is incident on the plasma off-axis lens array. n The plasma off-axis lenses correspond to n A focusing position, and the focusing position corresponding to each plasma off-axis lens is a position deviated from the central axis direction thereof; Determining the density distribution of each plasma off-axis lens in the plasma off-axis lens array according to different focusing positions corresponding to each plasma off-axis lens in the plasma off-axis lens array; The incident laser is incident on the plasma off-axis lens array, and the phase velocity of the incident laser propagating in each plasma off-axis lens in the plasma off-axis lens array changes, and the incident laser is divided into n beams of laser light with twisted propagation directions, and each beam of laser light output by the splitting is focused to a corresponding focusing position respectively.

8. The method for realizing relativistic laser off-axis focusing according to claim 7, characterized in that: Determining the density distribution of each plasma off-axis lens in the plasma off-axis lens array according to different focusing positions corresponding to each plasma off-axis lens in the plasma off-axis lens array includes: For any point on any plasma off-axis lens in the plasma off-axis lens array, the plasma density Determined by the following formula: in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the dielectric constant of vacuum, is the object light frequency, is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the focus at the minimum value of the plasma off-axis lens density. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ; The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

9. The method for realizing relativistic laser off-axis focusing according to claim 7 or 8, characterized in that: The incident laser is a Gaussian laser pulse with linear polarization and relativistic intensity.

10. A device for realizing off-axis focusing of relativistic laser, characterized in that: It includes an incident laser generating device and a plasma off-axis lens array; The incident laser generating device outputs the incident laser and irradiates the incident laser onto the plasma off-axis lens array with a set density distribution. The incident laser is a relativistic intensity laser. The plasma off-axis lens array is composed of n The plasma off-axis lenses are arranged in an array. The incident laser is incident on the plasma off-axis lens array. n The plasma off-axis lenses correspond to n A focusing position, and the focusing position corresponding to each plasma off-axis lens is a position deviated from the central axis direction thereof; An incident laser is incident on the plasma off-axis lens array, and the phase velocity of the incident laser propagating in each plasma off-axis lens in the plasma off-axis lens array changes, and the incident laser is divided into n beams of laser light with twisted propagation directions, and each beam of laser light outputted by the beam splitting is focused to a corresponding focusing position, wherein the density distribution of each plasma off-axis lens in the plasma off-axis lens array is determined according to the different focusing positions corresponding to each plasma off-axis lens in the plasma off-axis lens array, including: for any point on any plasma off-axis lens in the plasma off-axis lens array, its plasma density Determined by the following formula: in Corresponding to wavelength is 1 μm The critical density of the laser, , are the unit charge and the mass of the electron, is the vacuum dielectric constant, is the object light frequency, is the relativistic factor of linearly polarized light, is the normalized amplitude of the laser, represents the minimum value of plasma off-axis lens density, h It represents the difference between the distance from any point on the plasma off-axis lens to the focus and the distance from the focus at the minimum value of the plasma off-axis lens density. d is the thickness of the plasma off-axis lens, and the minimum density of the plasma off-axis lens ; The above formula is used to determine the plasma density at different positions on the plasma off-axis lens, and then the density distribution of the plasma off-axis lens is determined.

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