Electron source, preparation method of electron source, electron gun and application of electron source

Abstract

The invention relates to an electron source, a preparation method of the electron source, an electron gun and application of the electron source. The electron source includes an optical fiber and an electron emission layer. The optical fiber comprises a fiber core used for transmitting laser and a wrapping layer wrapping the fiber core. A light leakage notch is formed in the light outlet end of the optical fiber along the radial direction of the optical fiber; the electron emission layer is arranged on the bottom wall surface of the light leakage gap, the electron emission layer at least comprises an electron excitation layer, the bottom wall surface of the light leakage gap is constructed to be a plane, and the projection of the electron excitation layer on the bottom wall surface covers the projection of the fiber core on the bottom wall surface. Low-dimensional materials such as zero-dimensional materials, one-dimensional materials or two-dimensional materials are adopted as materials of the electron excitation layer, the low-dimensional materials have the atomic-scale thickness, excited electrons can be emitted without in-vivo transmission, and the electron emission efficiency is high; and the low-dimensional material has the characteristics of no dangling bond, stable property, high melting point, difficulty in damage, good stability, long service life and the like.

Description

Technical Field

[0001] The present application relates to the technical field of electron sources, and particularly to an electron source, a preparation method of the electron source, an electron gun, and an application of the electron source. Background Art

[0002] An electron source is a device for generating vacuum electrons. Traditional electron sources are mainly classified into thermionic electron sources, field emission electron sources, and photoemission electron sources according to the excitation method. Thermionic electron sources mainly select metal materials. When heated to thousands of degrees Celsius, electrons are thermally excited to escape from the material surface to form vacuum electrons. Field emission electron sources mainly select metal tips, and under the action of a strong electric field applied externally, a tip discharge effect is generated. A photoemission electron source uses a metal material as a photocathode, and a laser is used to irradiate the laser cathode material to generate electrons.

[0003] However, most of the reported photoemission electron sources adopt the form of laser side irradiation of metal tips, which has disadvantages such as high operation difficulty of the irradiation method. The electron sources in the traditional technology cannot balance the emission efficiency and stability. How to provide an electron source with high electron emission efficiency and good stability has become an urgent technical problem to be solved at present. Summary of the Invention

[0004] Based on this, in view of the problem that the electron sources in the traditional technology cannot balance the emission efficiency and stability, it is necessary to provide an electron source, a preparation method of the electron source, an electron gun, and an application of the electron source.

[0005] According to a first aspect of the present application, there is provided an electron source, including:

[0006] An optical fiber, including a core for transmitting laser and a cladding layer wrapping the core; a light leakage notch is formed along the radial direction of the light output end of the optical fiber; and

[0007] An electron emission layer is disposed on the bottom wall surface of the light leakage notch, and the electron emission layer at least includes an electron excitation layer. The bottom wall surface of the light leakage notch is configured as a plane, and the projection of the electron excitation layer on the bottom wall surface covers the projection of the core on the bottom wall surface;

[0008] Wherein, the electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material.

[0009] In one embodiment, the bottom wall surface of the light leakage notch extends along the extending direction of the optical fiber.

[0010] In one embodiment, the light leakage notch is disposed on the cladding layer, and along the radial direction of the optical fiber, the maximum distance between the bottom wall surface of the light leakage notch and the core is less than or equal to a preset value.

[0011] In one embodiment, the preset value is D, where 0 μm < D ≤ 3 μm.

[0012] In one embodiment, the bottom wall surface of the light leakage gap is spaced apart from the core, and the bottom wall surface of the light leakage gap is parallel to the tangent plane of the outer surface of the core; or

[0013] The bottom wall surface of the light leakage gap is configured as a plane partially formed on the core.

[0014] In one embodiment, the thickness of the electron excitation layer is less than or equal to 50 nm.

[0015] In one embodiment, the angle between the axial direction of the one-dimensional material in the electron excitation layer and the emission direction of the emitted laser is 0 to 90°.

[0016] In one embodiment, the electron excitation layer includes at least two two-dimensional materials stacked in sequence along the laser emission direction; or,

[0017] The electron excitation layer includes at least two two-dimensional materials with different materials connected to each other in the same plane.

[0018] In one embodiment, the material in the electron excitation layer includes one-dimensional material and zero-dimensional material disposed at the end and / or side of the one-dimensional material.

[0019] In one embodiment, the electron excitation layer includes zero-dimensional material and two-dimensional material, and the zero-dimensional material is disposed on the surface of the two-dimensional material.

[0020] In one embodiment, the electron excitation layer includes one-dimensional material and two-dimensional material, and the one-dimensional material is disposed on the surface of the two-dimensional material.

[0021] In one embodiment, the electron source further includes a conductive connection layer disposed at least on the bottom wall surface of the light leakage gap, and the conductive connection layer is electrically connected to the electron excitation layer.

[0022] In one embodiment, the electron excitation layer includes a first part and a second part disposed on the bottom wall surface of the light leakage gap and connected to each other;

[0023] The projection of the first part on the bottom wall surface covers the projection of the core on the bottom wall surface; the second part is located outside the first part and is electrically connected to the conductive connection layer.

[0024] In one embodiment, the conductive connection layer includes a first conductive portion provided on the bottom wall surface of the light leakage notch, and a second conductive portion connected to the first conductive portion and disposed on the circumferential side surface of the optical fiber;

[0025] The first conductive portion overlaps with the second portion of the electron excitation layer.

[0026] In one embodiment, the conductive connection layer includes a first metal layer and a second metal layer stacked;

[0027] The adhesion of the first metal layer is greater than the adhesion of the second metal layer.

[0028] In one embodiment, the electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on one side of the electron excitation layer close to the bottom wall surface of the light leakage notch; or,

[0029] The auxiliary layer is stacked on one side of the electron excitation layer away from the bottom wall surface of the light leakage notch.

[0030] In one embodiment, the auxiliary layer satisfies at least one of the following conditions:

[0031] (1) The auxiliary layer includes at least one of a conductive support layer and a heat dissipation support layer;

[0032] (2) The thickness of the auxiliary layer is 0.1 nm to 10 nm, and the light transmittance is more than 10%.

[0033] In one embodiment, the auxiliary layer includes a conductive support layer, and the conductive support layer is electrically connected to the conductive connection layer.

[0034] In one embodiment, the auxiliary layer includes a conductive support layer, the material of the conductive support layer includes a conductive metal, the laser wavelength in the optical fiber is 200 nm to 10 μm, the pulse power is 1 nw to 1 w, and the repetition frequency is 0 Hz to 10 GHz.

[0035] According to the second aspect of the present application, a method for preparing an electron source is provided, including:

[0036] Providing an optical fiber; wherein, the optical fiber includes a core for transmitting laser and a cladding layer wrapped around the core; a light leakage notch is formed along the radial direction of the light output end of the optical fiber;

[0037] Forming an electron emission layer on the bottom wall surface of the light leakage notch;

[0038] Among them, the electron emission layer at least includes an electron excitation layer, the bottom wall surface of the light leakage notch is configured as a plane, and the projection of the electron excitation layer on the bottom wall surface covers the projection of the fiber core on the bottom wall surface; the electron excitation layer includes at least one of zero-dimensional materials, one-dimensional materials, and two-dimensional materials.

[0039] In one embodiment, before or after forming the electron emission layer on the bottom wall surface of the light leakage notch, the method for preparing the electron source further includes:

[0040] Form a conductive connection layer on the bottom wall surface of the light leakage notch so that the conductive connection layer overlaps with the electron excitation layer.

[0041] In one embodiment, forming the conductive connection layer on the bottom wall surface of the light leakage notch so that the conductive connection layer overlaps with the electron excitation layer specifically includes:

[0042] Form a fiber core protection layer on the bottom wall surface of the light leakage notch, where the projection of the fiber core protection layer on the bottom wall surface covers the projection of the fiber core on the bottom wall surface;

[0043] Form a conductive material layer covering the fiber core protection layer on the optical fiber;

[0044] Remove the fiber core protection layer and the part of the conductive material layer disposed on the fiber core protection layer to form the conductive connection layer.

[0045] In one embodiment, forming the electron emission layer on the bottom wall surface of the light leakage notch specifically includes:

[0046] Set the electron excitation layer and the bottom wall surface of the light leakage notch opposite to each other and parallel to each other in the first direction;

[0047] Drive the optical fiber to move in the first direction to contact the electron excitation layer;

[0048] Attach the electron excitation layer to the bottom wall surface of the light leakage notch at a preset temperature.

[0049] According to the third aspect of the present application, an electron gun is provided. The electron gun includes a housing, a grid, an anode, and the electron source according to any one of the above embodiments;

[0050] The electron source is fixed in the housing, and the grid and the anode are sequentially arranged on the electron emission side of the electron source.

[0051] According to the fourth aspect of the present application, there is provided an application of the electron source described in any of the above embodiments, and the application of the electron source includes at least one of an electron microscope, an electron beam lithography machine, a free electron laser, an X-ray tube, an electron accelerator, an electron diffraction device, and a display.

[0052] In the solution of the present application, when the electron source is used, the laser transmitted in the core of the optical fiber can be transmitted from the light incident end of the optical fiber towards the light output end of the optical fiber. Since the light leakage gap is constructed along the radial direction of the optical fiber at the light output end, in this way, the laser transmitted in the core of the optical fiber can generate an evanescent wave at the bottom wall surface of the light leakage gap. And since the electron excitation layer is arranged on the bottom wall surface of the light leakage gap, and the projection of the electron excitation layer on the bottom wall surface covers the projection of the core on the bottom wall surface, therefore, the laser transmitted in the core of the optical fiber can interact with the electron excitation layer through the evanescent wave, so that the electrons in the electron excitation layer absorb the energy of the evanescent wave and transition. These electrons can escape outside the electron excitation layer, and thus the excitation of electrons can be realized. The present application uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials, or two-dimensional materials as the materials of the electron excitation layer. The low-dimensional materials have an atomic-level thickness, and the excited electrons can be emitted without passing through in-body transmission, and the electron emission efficiency is high; moreover, the low-dimensional materials have no dangling bonds, are stable in nature and have a high melting point, are not easily damaged, and can be applied to the scenario of high-power excitation, and have characteristics such as good stability and long service life; in addition, the low-dimensional materials also have a high optical nonlinear effect and discrete electron energy levels, so that the laser can better interact with the electron excitation layer to generate energy resonance and excite the electrons in the electron excitation layer. These electrons are excited and detached into the vacuum, and an electron beam can be formed, and the electron beam tunneling-emitted from the electron excitation layer has the characteristics of concentrated energy and small energy dispersion. In addition, the low-dimensional materials and the optical fiber can be directly integrated. The optical fiber transmits the laser and serves as the carrier of the low-dimensional materials, and can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, can be applied to different application scenarios, and does not require a complex optical path, and has characteristics such as small volume and high integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Shows a cross-sectional view of the electron source in the first embodiment of the present application along the extension direction of the optical fiber.

[0054] Figure 2 Shows Figure 1 An enlarged schematic view of part A of

[0055] Figure 3 Shows Figure 1 The cross-sectional view of the electron source shown along the direction perpendicular to the extension direction of the optical fiber.

[0056] Figure 4 Shows a cross-sectional view of the electron source in the second embodiment of the present application along the direction perpendicular to the extension direction of the optical fiber.

[0057] Figure 5 Shows a cross-sectional view of the electron source in the third embodiment of the present application along the direction perpendicular to the extension direction of the optical fiber.

[0058] Figure 6 Shows a cross-sectional view of the electron source in the fourth embodiment of the present application along the direction perpendicular to the extension direction of the optical fiber.

[0059] Figure 7 Shows a circuit block diagram of the electron source and the anode in an embodiment of the present application.

[0060] Figure 8 Shows a cross-sectional view of the electron source in the fifth embodiment of the present application along the direction perpendicular to the extension direction of the optical fiber.

[0061] Figure 9 Shows a schematic flow chart of the preparation method of the electron source in an embodiment of the present application.

[0062] Figure 10 Shows a schematic diagram of the process of the preparation method of the electron source in an embodiment of the present application.

[0063] Figure 11 Shows a schematic structural diagram of the electron gun in an embodiment of the present application.

[0064] Figure 12 Shows a cross-sectional view of the electron source in the sixth embodiment of the present application along the direction perpendicular to the extension direction of the optical fiber.

[0065] Reference numerals:

[0066] 10, electron gun;

[0067] 100, electron source;

[0068] 110, optical fiber; 111, core; 112, cladding; 1101, light incident end; 1102, light output end; h, light leakage notch; h1, bottom wall surface; h2, side wall surface;

[0069] 120, electron emission layer; 121, electron excitation layer; 1211, first part; 1212, second part; 122, auxiliary layer;

[0070] 130, conductive connection layer; 131, first conductive part; 132, second conductive part;

[0071] 200, gate; 210, second electron channel;

[0072] 300, anode; 310, first electron channel;

[0073] 20, temporary substrate

[0074] 30. Perforated glass slide;

[0075] 40. Annular heating sheet. Detailed implementation manners

[0076] To make the above objects, features, and advantages of the present application more apparent and understandable, the following will describe the detailed implementation manners of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0077] In the description of the present application, it should be understood that if terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the accompanying drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present application.

[0078] In addition, if terms such as "first" and "second" appear, these terms are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0079] In the present application, unless otherwise clearly specified and limited, if terms such as "install", "connect", "connect", "fix", etc. appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0080] In this application, unless otherwise clearly specified and defined, when a first feature is described as being "on" or "under" a second feature or the like, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature has a lower horizontal height than the second feature.

[0081] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are only for the purpose of illustration and do not represent the only implementation.

[0082] In the traditional technology, the thermionic electron source mainly selects materials with metallic properties such as tungsten wire and lanthanum hexaboride. When heated to thousands of degrees Celsius, electrons are thermally excited to escape from the material surface to form vacuum electrons. The field emission electron source mainly selects metal tips such as tungsten. Under the action of a strong electric field applied from the outside, the tip discharge effect is generated. Among them, the electron beam emitted by the thermionic electron source can work in a relatively poor vacuum environment, has good adaptability to the environment and good stability, but has a lower brightness and poor coherence. The electron beam of the field emission electron source has a high brightness and good coherence, but has high requirements for the vacuum degree and is very sensitive to vibrations. Whether it is a thermionic electron source or a field emission electron source, the regulation of electron emission properties is limited, and it is impossible to balance the emission efficiency and stability.

[0083] In the traditional technology, the photoemission electron source uses metal materials such as Au as the material of the electron emission layer, and the thickness is above 50 nm, and even reaches several hundred nanometers. However, the inventors of this application have found through research that the electron emission layer made of metal materials has a relatively large thickness, and the distance between the bottom layer directly acting with the laser and the surface layer for electron emission is relatively far (50 nm to several hundred nanometers). During the process of electrons excited from the bottom layer passing through the electron emission layer, they are easily affected by the scattering of the metal lattice, thereby affecting the emission efficiency. Moreover, metal materials are easily damaged under high-power laser irradiation, which affects the service life of the electron emission layer, and thus affects the emission efficiency and stability of electrons.

[0084] In the traditional technology, there is also a type of photoemission electron source where electrons are excited by an external laser incident on the surface of a metal tip. Since the size of the metal tip is in the nanometer range, it is difficult to align the laser spot with the metal tip. If a high-magnification microscope is set up to align the external laser with the metal tip, the overall cost will increase.

[0085] In addition, in the traditional technology, graphene is used as a saturable absorber. Graphene has broadband saturable absorption characteristics and a fast recovery time, and is used in the Q-switching and mode-locking of lasers, or graphene is used to adjust the laser spectrum for sensing detection. However, there are obvious differences between graphene laser regulation and graphene electron emission. Graphene electron emission is based on the photoelectric effect, while graphene laser regulation is based on the principle of light absorption. For the described graphene saturable absorber, it mainly utilizes the situation where the light absorption rate (or transmittance) of graphene increases (or decreases) as the incident light power increases and finally reaches the saturation threshold. It is mainly applied in lasers to generate laser pulses. For example, in the ring fiber resonator of a fiber laser, when the light circulates in the resonator and the light power passing through the graphene saturable absorber exceeds its saturation absorption threshold, due to the saturable absorption effect, the light intensity in the cavity will instantaneously drop below the saturation absorption threshold, and this part of the dropped light energy is output in the form of pulses from the beam splitter of the cavity.

[0086] Based on this, it is necessary to provide an electron source that can balance the electron emission efficiency and stability.

[0087] This application uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials, or two-dimensional materials as the material of the electron excitation layer. The low-dimensional materials emit electrons under laser irradiation due to the photoelectric effect. The low-dimensional materials have atomic-level thickness, no dangling bonds, and stable properties, thus having characteristics such as good stability and high service life. Moreover, the low-dimensional materials can be directly integrated with optical fibers, and the optical fibers can provide a stable excitation source with adjustable wavelength, polarization, and optical mode, and can be applied to different application scenarios.

[0088] Figure 1 The structural schematic diagram of the electron source 100 in an embodiment of this application is shown.

[0089] Please refer to Figure 1 and, in combination, refer to Figure 2 and Figure 3 According to the first aspect of this application, an electron source 100 is provided, which includes an optical fiber 110 and an electron emission layer 120.

[0090] The optical fiber 110 includes a core 111 for transmitting laser light and a cladding layer 112 wrapped around the core 111. The refractive index of the cladding layer 112 is lower than that of the core 111. Therefore, the laser light can be confined within the core 111 by the cladding layer 112 and propagate. A coating layer is also provided on the outer surface of the cladding layer 112 to protect the cladding layer 112 and the core 111.

[0091] The optical fiber 110 has a light input end 1101 and a light output end 1102. The light input end 1101 is used to couple to a laser source so that the laser light emitted by the laser source can be transmitted through the core 111 of the optical fiber 110. Among them, the laser source can be a laser. The optical fiber 110 is a transmission medium for laser light and a carrier for low-dimensional materials. The optical fiber 110 can be a single-mode optical fiber, a multi-mode optical fiber, a polarization-maintaining optical fiber, or a multi-core optical fiber, etc.

[0092] A light leakage notch h is formed along the radial direction of the optical fiber 110 at the light output end 1102 of the optical fiber 110. The electron emission layer 120 is provided on the bottom wall surface h1 of the light leakage notch h, and the electron emission layer 120 at least includes an electron excitation layer 121. The bottom wall surface h1 of the light leakage notch h is configured as a plane, and the projection of the electron excitation layer 121 on the bottom wall surface h1 covers the projection of the core 111 on the bottom wall surface h1.

[0093] Optionally, the light leakage notch h further has a side wall surface h2 extending along the radial direction of the optical fiber 110, and the bottom wall surface h1 and the side wall surface h2 jointly define the light leakage notch h.

[0094] Among them, the electron excitation layer 121 includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material.

[0095] The electron excitation layer 121 may include a zero-dimensional material. A zero-dimensional material refers to a material whose size in the three-dimensional spatial scale direction is in the nanoscale, such as nanoparticles, atomic clusters, and quantum dots, etc., which are generally composed of a small number of atoms and molecules. There are many zero-dimensional carbon nanomaterials, such as carbon black, nanodiamond, diamond color center, nanometer fullerene C 60 or carbon-coated nanometal particles, etc. The zero-dimensional material has typical discrete energy levels. Under the action of laser excitation, electrons are mainly tunneling-excited from the discrete energy levels, so that the electron beam tunneling-emitted from the electron excitation layer 121 has the characteristics of concentrated energy and small energy dispersion.

[0096] The electron excitation layer 121 may also include one-dimensional materials. Electrons in the one-dimensional materials can be transported along the linear chain of the one-dimensional materials. Considering that the electron excitation layer 121 is provided on the bottom wall surface h1 of the light leakage gap h, and the bottom wall surface h1 of the light leakage gap h is configured as a plane and extends along the extension direction of the optical fiber 110, thus, it is beneficial for the electrons emitted by the electron source 100 to be efficiently emitted along the extension direction of the optical fiber 110. The one-dimensional materials have the characteristics of a small radius of curvature (nanoscale), can enhance the light-matter interaction and provide a large field enhancement factor, ensure multi-photon emission, optical field emission, etc., and are applied to scenarios requiring a high-brightness electron source.

[0097] The one-dimensional materials can be nanotubes, nanorods or nanowires, nanobelts or coaxial nanocables, etc.

[0098] The nanotubes can be carbon nanotubes. Carbon nanotubes can be regarded as seamless tubular structures formed by winding single-layer or multi-layer graphite according to certain rules. The nanotubes can also be silicon (Si) nanotubes, selenium (Se) nanotubes, tellurium (Te) nanotubes, bismuth (Bi) nanotubes, boron nitride (BN) nanotubes, boron-nitrogen co-doped carbon nanotubes (BCN nanotubes), tungsten disulfide (WS2) nanotubes, molybdenum disulfide (MoS2) nanotubes or titanium dioxide (TiO2) nanotubes, etc.

[0099] The material of the nanowires can be silicon (Si) or germanium (Ge); the nanowires can also be oxide nanowires, such as tin oxide (SnO) or zinc oxide (ZnO), etc.; of course, the nanowires can also be nitride nanowires, such as gallium nitride (GaN) or silicon nitride (Si3N4), etc.; the nanowires can also be sulfide nanowires, such as cadmium sulfide (CdS) and zinc sulfide (ZnS), etc.; the nanowires can also be ternary compound nanowires, such as barium titanate (BaTiO3) and lead titanate (PbTiO3), etc.

[0100] The nanobelts are quite different from the above two nanoscale structures (nanotubes and nanowires). Their cross-sections are not close to circular like those of nanotubes or nanowires, but are quadrilateral, and the aspect ratio distribution range is generally from several to more than a dozen. The material of the nanobelts can be oxides, such as tin oxide (SnO) or zinc oxide (ZnO), etc.

[0101] The coaxial nanocables can be graphite / boron nitride (C / BN) coaxial nanocables or silicon carbide / sulfur dioxide (CSi / SiO2) coaxial nanocables, etc.

[0102] The electron excitation layer 121 may also include a two-dimensional material. The electrons in the two-dimensional material can be transmitted along a two-dimensional plane. Considering that the electron excitation layer 121 is disposed on the bottom wall surface h1 of the light leakage gap h, and the bottom wall surface h1 of the light leakage gap h is configured as a plane and extends along the extension direction of the optical fiber 110, in this way, it is beneficial for the electrons emitted by the electron source 100 to be emitted efficiently along the extension direction of the optical fiber 110. Moreover, compared with setting a thinner metal layer on the optical fiber, it will cause the melting point of the metal layer to decrease, which will further lead to the problem that the metal layer is easily damaged. The two-dimensional material selected in this application has no dangling bonds, is relatively stable, has a high melting point, is not easily damaged, and is suitable for high-power excitation and high-beam-current electron sources 100. In addition, the energy levels of the two-dimensional material are more discrete, and the energy of the electron beam emitted by tunneling is more concentrated and the energy dispersion is smaller.

[0103] The two-dimensional material has the characteristic of atomic layer thickness. The thickness of the two-dimensional material can be the thickness of a single atomic layer or the thickness of multiple atomic layers. During the interaction between the laser and the two-dimensional material, it hardly affects the light transmission mode and has high stability. Moreover, the excited electrons can be directly emitted without internal scattering in the material, ensuring the purity of the properties of the emitted electrons and an extremely narrow pulse width.

[0104] The two-dimensional material can be graphene, transition metal sulfide, two-dimensional perovskite, two-dimensional diamond, boron nitride, etc.

[0105] Taking the two-dimensional material selected as graphene as an example for illustration, the carbon atoms in graphene are bonded in the plane in the form of covalent bonds to form a hexagonal honeycomb planar structure. The electron excitation layer 121 can have a thickness of one atomic layer, about 0.34 nanometers; the electron excitation layer 121 can also have a thickness of several or dozens of atomic layers.

[0106] Of course, the present application is not limited thereto. The electron excitation layer 121 also includes two or more of zero-dimensional materials, one-dimensional materials, and two-dimensional materials. In this way, when the electron source 100 is used, the laser transmitted in the core 111 of the optical fiber 110 can be transmitted from the light incident end 1101 of the optical fiber 110 towards the light output end 1102 of the optical fiber 110. Since the light leakage notch h is formed in the radial direction of the optical fiber 110 at the light output end 1102 of the optical fiber 110, the laser transmitted in the core 111 of the optical fiber 110 can generate an evanescent wave at the bottom wall surface h1 of the light leakage notch h. And since the electron emission layer 120 is disposed on the bottom wall surface h1 of the light leakage notch h, and the projection of the electron excitation layer 121 on the bottom wall surface h1 covers the projection of the core 111 on the bottom wall surface h1, the laser transmitted in the core 111 of the optical fiber 110 can interact with the electron excitation layer 121 through the evanescent wave, so that the electrons in the electron excitation layer 121 absorb the energy of the evanescent wave and transition. These electrons can escape outside the electron excitation layer 121, and thus the excitation of electrons can be realized. The electron source 100 uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials, or two-dimensional materials as the material of the electron excitation layer 121, and the electron excitation layer 121 is disposed on the optical fiber 110 to realize the excitation of electrons, eliminating the complex spatial light coupling structure set due to the introduction of external laser, and also eliminating the high-magnification microscope set to solve the alignment problem of the metal tip, which can reduce the process cost of the electron gun.

[0107] Compared with setting a metal layer on the optical fiber tip and directly interacting the laser transmitted in the optical fiber with the metal layer to excite electrons (electrons are easily affected by lattice scattering during the process of passing through the metal layer, resulting in a lower electron emission efficiency. In addition, the conduction band of the metal material is a half-filled band, resulting in a wide energy distribution of the electrons emitted by the excited metal layer), the present application uses low-dimensional materials such as zero-dimensional materials, one-dimensional materials, or two-dimensional materials as the material of the electron excitation layer 121. The low-dimensional materials have an atomic-level thickness, and the excited electrons can be emitted without passing through in vivo transmission, with a high electron emission efficiency; moreover, the low-dimensional materials have no dangling bonds, are stable in nature and have a high melting point, are not easily damaged, and can be applied to the scenario of high-power excitation, with characteristics such as good stability and high service life; in addition, the low-dimensional materials also have a high optical nonlinear effect and discrete electron energy levels, enabling the laser to better interact with the electron excitation layer 121 to generate energy resonance and excite the electrons in the electron excitation layer 121. These electrons are excited and detached into the vacuum, and can form an electron beam, and the electron beam tunneling and emitting from the electron excitation layer 121 has the characteristics of concentrated energy and small energy dispersion.

[0108] In addition, the low-dimensional material and the optical fiber 110 can be directly integrated. The optical fiber transmits laser light and serves as a carrier for the low-dimensional material, capable of providing a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios without the need to provide a complex optical path, and has the characteristics of small size and high integration.

[0109] It should be noted that the wavelength of the laser can be the wavelength at which electrons in the electron excitation layer 121 absorb a photon and transition. For example, the wavelength is in the visible-near infrared-ultraviolet range. The wavelength of the laser can also be the wavelength at which electrons in the electron excitation layer 121 absorb multiple photons and transition. For example, the wavelength is outside the visible-near infrared-ultraviolet range, and no specific limitation is made here.

[0110] In some embodiments, the bottom wall surface h1 of the light leakage notch h is configured as a plane, and the bottom wall surface h1 of the light leakage notch h extends along the extending direction of the optical fiber 110. In this way, the laser transmitted in the core 111 can generate a more uniform evanescent wave at the bottom wall surface h1 of the light leakage notch h, enabling the laser to better interact with the electron excitation layer 121 through the evanescent wave, so as to better excite the electron excitation layer 121 to emit electrons outward, which is beneficial to the efficient emission of electrons emitted by the electron source 100 along the extending direction of the optical fiber 110.

[0111] In some embodiments, the bottom wall surface h1 of the light leakage notch h is configured as a plane, and the bottom wall surface h1 of the light leakage notch h is spaced from the core 111, and the bottom wall surface h1 of the light leakage notch h is parallel to the tangent plane of the outer surface of the core 111.

[0112] In some other embodiments, as Figure 3 and Figure 6 shown, the bottom wall surface h1 of the light leakage notch h is tangent to the outer surface of the core 111.

[0113] In still some other embodiments, as Figure 4 shown, the bottom wall surface h1 of the light leakage notch h is configured as a plane partially formed on the core 111. The core 111 and the cladding 112 can be cut simultaneously by a cutting method to form the light leakage notch h (wherein, along the radial direction of the core 111, the size of the core 111 cut is greater than 0 μm and less than 3 μm), and a part of the bottom wall surface h1 of the light leakage notch h is formed on the core 111, and another part of the bottom wall surface h1 of the light leakage notch h is formed on the cladding 112. In this embodiment, the electron excitation layer 121 can directly cover the core 111 of the optical fiber 110 or indirectly cover the core 111 of the optical fiber 110, and no specific limitation is made here.

[0114] In yet some other embodiments, as Figure 5As shown, the light leakage gap h is provided in the cladding layer 112. Along the radial direction of the optical fiber 110, the maximum distance between the bottom wall surface h1 of the light leakage gap h and the core 111 is less than or equal to a preset value.

[0115] Optionally, the preset value is D, where 0μm < D ≤ 3μm.

[0116] Specifically, in the embodiments such as Figure 1 , Figure 4 and Figure 5 shown, it is equivalent to covering the electron excitation layer 121 on one side of the core 111 along its radial direction. In this way, the laser transmitted in the core 111 generates an evanescent wave at the bottom wall surface h1 of the light leakage gap h, and this part of the laser can better interact with the electron excitation layer 121 through the evanescent wave to well excite the electron excitation layer 121 to emit electrons outward.

[0117] In some embodiments, the thickness of the electron excitation layer 121 is less than or equal to 50nm.

[0118] It can be understood that the thickness of the electron excitation layer 121 is in the nanometer order, and the thickness of the electron excitation layer 121 is small. In this way, it is more conducive to reducing the process of the excited electrons undergoing in-body transmission in the electron excitation layer 121, more conducive to improving the emission efficiency and emission power of the electrons, and thus the electron source 100 can be used to realize an electron beam with ultrashort pulses.

[0119] In some embodiments, the angle between the axial direction of the one-dimensional material in the electron excitation layer 121 and the emission direction of the emitted laser is 0 to 90°, for example, it can be 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° or 90°.

[0120] In some embodiments, the axial direction of the one-dimensional material is the same as the emission direction of the laser, so that point emission of the electron source 100 can be realized and the resolution is high. If a low-density arrangement of one-dimensional materials is adopted, the energy dispersion of the emitted electrons is low and the brightness is high. If a high-density arrangement of one-dimensional materials is adopted, a large beam current of the electron source can be realized. Here, the low density refers to the number of one-dimensional materials per unit line segment. For example, a density less than n pieces / nm is low density, and a density greater than n pieces / nm is high density, where n can be 1, 2 or 3.

[0121] In some embodiments, the axial direction of the one-dimensional material has an angle with the emission direction of the laser, and the angle can be a right angle or an acute angle. Laser excitation of the one-dimensional material can generate a linear electron source.

[0122] In some embodiments, the electron excitation layer 121 includes at least one layer of two-dimensional material.

[0123] Optionally, the electron excitation layer 121 includes at least two layers of two-dimensional materials stacked in sequence along the laser emission direction, or the electron excitation layer 121 includes at least two two-dimensional materials with different materials connected to each other in the same plane.

[0124] In some embodiments, at least two layers of two-dimensional materials are stacked, or the electron excitation layer 121 includes at least two two-dimensional materials with different materials connected to each other in the same plane, thereby forming a vertical heterojunction or a planar heterojunction. The heterojunction structure can enhance the interaction between light and two-dimensional materials, achieve efficient electron emission under laser power, and the heterojunction has the function of interfacial energy band regulation. Through material design and twist angle regulation, special interfacial states can be obtained to achieve high-brightness and low-energy-dispersion electron emission.

[0125] In some embodiments, the materials in the electron excitation layer 121 include one-dimensional materials and zero-dimensional materials disposed at the ends and / or sides of the one-dimensional materials.

[0126] In this application, by combining zero-dimensional materials with one-dimensional materials and disposing the zero-dimensional materials at the ends and / or sides of the one-dimensional materials, that is, using zero-dimensional materials to modify the surface structure of one-dimensional materials. Both zero-dimensional materials and one-dimensional materials have typical discrete energy levels. Under the action of laser, electrons are mainly excited by tunneling from discrete energy levels, and the emitted electrons have characteristics such as concentrated energy, small energy dispersion, and high emission efficiency.

[0127] In some embodiments, the electron excitation layer 121 includes zero-dimensional materials and two-dimensional materials, and the zero-dimensional materials are disposed on the surface of the two-dimensional materials.

[0128] In this application, the zero-dimensional materials are disposed on the surface of the two-dimensional materials. The two-dimensional materials can not only serve as a support layer for carrying the zero-dimensional materials, but also avoid the addition of the following conductive connection layer 130 by using conductive two-dimensional materials, that is, the two-dimensional materials can serve as an auxiliary layer for the zero-dimensional materials to achieve the functions of support and conduction.

[0129] In some embodiments, the electron excitation layer 121 includes one-dimensional materials and two-dimensional materials, and the one-dimensional materials are disposed on the surface of the two-dimensional materials; optionally, the angle between the axial direction of the one-dimensional materials and the surface of the two-dimensional materials is 0 to 90°.

[0130] In this application, the one-dimensional materials are disposed on the surface of the two-dimensional materials. The two-dimensional materials can not only serve as a support layer for carrying the one-dimensional materials, but also avoid the addition of the following conductive connection layer 130 by using conductive two-dimensional materials, that is, the two-dimensional materials can serve as an auxiliary layer for the one-dimensional materials to achieve the functions of support and conduction.

[0131] In some embodiments, the zero-dimensional materials, one-dimensional materials or two-dimensional materials independently include doping elements.

[0132] This application improves the conductivity and electron emission performance of low-dimensional materials by doping elements into the low-dimensional materials. For example, doping phosphorus elements can improve the conductivity of low-dimensional materials; doping hetero elements can improve the electron emission performance of low-dimensional materials.

[0133] Optionally, the doping element includes at least one of boron, nitrogen, phosphorus, lithium, and potassium.

[0134] In some embodiments, referring to Figures 1 - 6 , the electron source 100 further includes a conductive connection layer 130, and the conductive connection layer 130 is at least disposed on the bottom wall surface h1 of the light leakage notch h and is electrically connected to the electron excitation layer 121.

[0135] As shown in FIGS. 1-5, the conductive connection layer 130 can be formed on the bottom wall surface h1 of the light leakage notch h first, and then the electron excitation layer 121 electrically connected to the conductive connection layer 130 can be formed on the bottom wall surface h1 of the light leakage notch h; as Figure 6 shown, the electron excitation layer 121 can also be formed on the bottom wall surface h1 of the light leakage notch h first, and then the conductive connection layer 130 electrically connected to the electron excitation layer 121 can be formed on the bottom wall surface h1 of the light leakage notch h. There is no specific limitation here.

[0136] The conductive connection layer 130 can be a conductive thin film. Specifically, the conductive connection layer 130 can be a metal thin film, a graphite thin film, or a low-dimensional material thin film, etc.

[0137] It should be added that the projection of the conductive connection layer 130 on the bottom wall surface h1 is staggeredly arranged with the projection of the core 111 on the bottom wall surface h1.

[0138] In this way, the electron excitation layer 121 can be electrically connected to the negative electrode of the power supply through the conductive connection layer 130. On the one hand, the power supply can be used to supplement electrons to the electron excitation layer 121, which is beneficial for the electron excitation layer 121 to continuously emit electrons under the excitation of laser; on the other hand, the direction and convergence of the electrons emitted from the electron excitation layer 121 can be regulated by the voltage applied to the conductive connection layer 130 by the power supply.

[0139] Exemplarily, as Figure 7As shown, the electron source 100 is applied to the electron gun 10. The electron gun 10 further includes an anode 300. The anode 300 has a first electron channel 310 for allowing the electrons emitted from the electron excitation layer 121 to pass through. A preset voltage is provided between the anode 300 and the conductive connection layer 130, such that a preset electric field is formed between the anode 300 and the conductive connection layer 130. As a result, the electrons emitted from the electron excitation layer 121 are emitted towards the first electron channel 310 of the anode 300 under the drive of the preset electric field and pass through the first electron channel 310. Specifically, the electron excitation layer 121 is electrically connected to the negative electrode of the power supply through the conductive connection layer 130, and the anode 300 is electrically connected to the positive electrode of the power supply, so that a preset voltage is provided between the anode 300 and the conductive connection layer 130, and the electron excitation layer 121 and the anode 300 are arranged at intervals along the extending direction of the optical fiber 110. In this way, it is beneficial to form a uniform electric field along the extending direction of the optical fiber 110 by using the anode 300, and it is more beneficial for the electrons to be linearly accelerated along the extending direction of the optical fiber 110 and pass through the first electron channel 310.

[0140] In some embodiments, the electron excitation layer 121 includes a first part 1211 and a second part 1212 that are disposed on the bottom wall surface h1 of the light leakage notch h and are connected to each other. The projection of the first part 1211 on the bottom wall surface h1 covers the projection of the fiber core 111 on the bottom wall surface h1. The second part 1212 is located on the periphery of the first part 1211 and is electrically connected to the conductive connection layer 130.

[0141] Specifically, the second part 1212 can be directly in electrical contact with the conductive connection layer 130 to electrically connect the second part 1212 to the conductive connection layer 130; the second part 1212 can also be electrically connected to the conductive connection layer 130 through other conductive structures.

[0142] Optionally, the electron excitation layer 121 can be first disposed on the bottom wall surface h1 of the light leakage notch h, and then the conductive connection layer 130 can be overlapped on the second part 1212 of the electron excitation layer 121 (as Figure 6 shown); alternatively, the conductive connection layer 130 can be first disposed on the bottom wall surface h1 of the light leakage notch h, and then the electron excitation layer 121 can be disposed on the conductive connection layer 130, and the second part 1212 of the electron excitation layer 121 can be in electrical contact with the conductive connection layer 130 (as Figures 1 - 5 shown).

[0143] In this way, by electrically connecting the conductive connection layer 130 to the second part 1212 of the electron excitation layer 121 and combining the fact that the second part 1212 is located on the periphery of the first part 1211, the conductive connection layer 130 can supply electrons to the electron excitation layer 121 while not affecting the interaction between the fiber core 111 and the electron excitation layer 121, which is beneficial for the electron excitation layer 121 to continuously emit electrons outward under the excitation of the laser.

[0144] In some embodiments, the conductive connection layer 130 includes a first conductive portion 131 on the bottom wall surface h1 of the light leakage notch h, and a second conductive portion 132 connected to the first conductive portion 131 and disposed on the circumferential side surface of the optical fiber 110. The first conductive portion 131 overlaps with the second portion 1212 of the electron excitation layer 121.

[0145] In this way, the conductive connection layer 130 can cover more of the optical fiber 110, improving the bonding strength between the conductive connection layer 130 and the optical fiber, and also facilitating better use of the conductive connection layer 130 to supply electrons to the electron excitation layer 121.

[0146] In some embodiments, the conductive connection layer 130 includes a first metal layer and a second metal layer stacked, and the adhesion of the first metal layer is greater than that of the second metal layer.

[0147] Exemplarily, the material of the first metal layer is titanium, palladium or chromium, and the material of the second metal layer is gold.

[0148] In this way, the first metal layer with higher adhesion can make the conductive connection layer 130 better adhere to the optical fiber 110, improving the bonding strength between the conductive connection layer 130 and the optical fiber 110, and also facilitating the improvement of the service life of the conductive connection layer 130.

[0149] In some embodiments, please refer to Figure 8 , the electron emission layer 120 further includes an auxiliary layer 122. The auxiliary layer 122 is stacked on one side of the electron excitation layer 121 close to the bottom wall surface h1 of the light leakage notch h, or the auxiliary layer 122 is stacked on one side of the electron excitation layer 121 away from the bottom wall surface h1 of the light leakage notch h. Figure 8 An example is given where the auxiliary layer 122 is stacked on one side of the electron excitation layer 121 close to the bottom wall surface h1 of the light leakage notch h.

[0150] In this application, the auxiliary layer 122 is added. When the electron excitation layer 121 requires structural support, the auxiliary layer 122 is used to structurally support the electron excitation layer 121, that is, the electron excitation layer 121 is disposed on the auxiliary layer 122; or, when the electron excitation layer 121 cannot be directly connected and conducted with the conductive connection layer 130, it is connected to the conductive connection layer 130 through the conductive auxiliary layer 122, and the auxiliary layer 122 is used to achieve electron conduction between the electron excitation layer 121 and the conductive connection layer 130.

[0151] Optionally, the auxiliary layer 122 includes at least one of a conductive support layer and a heat dissipation support layer.

[0152] Optionally, the thickness of the auxiliary layer 122 is 0.1 nm - 100 nm. Specifically, the thickness of the auxiliary layer 122 is 0.3 nm to 10 nm.

[0153] Optionally, the light transmittance of the auxiliary layer 122 is 10% or more. Specifically, the light transmittance is 10% to 98%. Exemplarily, the light transmittance is 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 98%.

[0154] Optionally, the auxiliary layer 122 includes a conductive support layer, and the conductive support layer is electrically connected to the conductive connection layer 130.

[0155] In some embodiments, the auxiliary layer 122 includes a conductive support layer. The material of the conductive support layer includes a conductive metal. The laser wavelength in the optical fiber 110 is 200 nm to 10 μm, the pulse power is 1 nw to 1 w, and the repetition frequency is 0 Hz to 10 GHz.

[0156] In the present application, the auxiliary layer 122 uses a conductive metal and controls the laser parameters, thereby avoiding the problem of melting caused by laser irradiation of the conductive metal, and ensuring that the auxiliary layer has the functions of support and conduction.

[0157] The auxiliary layer 122 may also include a conductive support layer. As Figure 8 shown, the electron excitation layer 121 is disposed on the bottom wall surface h1 of the light leakage notch h through the auxiliary layer 122, and the auxiliary layer 122 has a bearing plane for bearing the electron excitation layer 121. The auxiliary layer 122 may be a light-transmitting material; the auxiliary layer 122 may also be a non-light-transmitting material, and the projection of the auxiliary layer 122 on the bottom wall surface h1 is located outside the projection of the core 111 on the bottom wall surface h1.

[0158] In this way, the bearing plane of the auxiliary layer 122 can be used to make the electron excitation layer 121 more flatly disposed on the bottom wall surface h1 of the light leakage notch h, and the interaction between the electron excitation layer 121 and the core 111 of the optical fiber 110 is not affected, which is beneficial to the formation of an electron beam with concentrated energy and small energy dispersion from the electrons tunneling and emitting within the electron excitation layer 121.

[0159] The auxiliary layer 122 may also include a heat dissipation support layer. Exemplarily, the material of the auxiliary layer 122 may be hexagonal boron nitride. Of course, the material of the auxiliary layer 122 may also be other materials that can dissipate heat for the electron excitation layer 121 and enable the electron excitation layer 121 to be flatly disposed on the bottom wall surface h1 of the light leakage notch h. In this way, the heat dissipation efficiency of the electron excitation layer 121 can be increased by using the auxiliary layer 122, so that the electron excitation layer 121 can emit a larger electron beam current.

[0160] Please refer to Figure 9 , according to the second aspect of the present application, a method for preparing an electron source 100 is provided, including the following steps:

[0161] S210. Provide an optical fiber 110. The optical fiber 110 includes a core 111 for transmitting laser light and a cladding layer 112 wrapped around the core 111. A light leakage notch h is formed along the radial direction of the light output end 1102 of the optical fiber 110.

[0162] Optionally, an appropriate length of the optical fiber 110 can be intercepted, the end coating layer of the optical fiber 110 can be removed, and one end of the cut optical fiber 110 can be processed to form the light output end 1102. Specifically, a cutting mechanism can be used to cut one end of the cut optical fiber 110 to form the light output end 1102. By using the cutting method to form the light output end 1102, the cross section where the light output end 1102 is located can be relatively flat.

[0163] Optionally, the bottom wall surface h1 and the side wall surface h2 of the light leakage notch h can be formed by cutting to enclose the light leakage notch h. Specifically, a cutting mechanism can be used to cut the optical fiber 110 along the radial and axial directions of the optical fiber 110 respectively to form the light leakage notch h.

[0164] By using the cutting method to form the light leakage notch h, the cross section where the bottom wall surface h1 of the light leakage notch h is located can be relatively flat, which is beneficial to forming a flat electron emission layer 120 on the bottom wall surface h1 of the light leakage notch h.

[0165] S220. Form an electron emission layer 120 on the bottom wall surface h1 of the light leakage notch h. The electron emission layer 120 at least includes an electron excitation layer 121. The bottom wall surface h1 of the light leakage notch h is configured as a plane, and the projection of the electron excitation layer 121 on the bottom wall surface h1 covers the projection of the core 111 on the bottom wall surface h1. Among them, the electron excitation layer 121 includes at least one of zero-dimensional materials, one-dimensional materials, and two-dimensional materials.

[0166] The electron excitation layer 121 can be formed by at least one of dry transfer, wet transfer, and direct growth.

[0167] In some embodiments, the electron excitation layer 121 is prepared by dry transfer. The preparation method includes: transferring zero-dimensional materials, one-dimensional materials, and / or two-dimensional materials to a tape by mechanical exfoliation, and transferring the zero-dimensional materials, one-dimensional materials, and / or two-dimensional materials to the bottom wall surface h1 of the light leakage notch h.

[0168] Taking two-dimensional materials as an example for illustration, the preparation process of forming the electron excitation layer 121 by dry transfer is as follows:

[0169] (1) The two-dimensional material can be thinned by mechanical exfoliation until an electron excitation layer 121 with a preset thickness is formed. Specifically, the two-dimensional material is adhered to a highly viscous tape A, and a low-viscosity tape B can be used to mechanically exfoliate along the crystal cleavage plane of the two-dimensional material repeatedly until the electron excitation layer 121 with a preset thickness is formed.

[0170] (2) Transfer the electron excitation layer 121 with a preset thickness to the temporary substrate 20 and remove the tape B on the electron excitation layer 121. Specifically, the tape B can be more easily peeled off by heating to peel the tape B from the electron excitation layer 121.

[0171] (3) Transfer the electron excitation layer 121 on the temporary substrate 20 to the bottom wall surface h1 of the light leakage notch h.

[0172] Optionally, the electron excitation layer 121 is made of a two-dimensional material, and the material of the temporary substrate 20 can be a polycarbonate propylene film.

[0173] Of course, the present application is not limited thereto. The dry transfer method can also be combined with the direct growth method (such as chemical vapor deposition). For example, an electron excitation layer 121 with a preset thickness is grown on the substrate to be peeled, and then the electron excitation layer 121 is transferred from the substrate to be peeled to the temporary substrate 20 by acid etching to remove the substrate to be peeled or by hand tearing, and then the electron excitation layer 121 on the temporary substrate 20 is transferred to the bottom wall surface h1 of the light leakage notch h. Among them, the substrate to be peeled can be a metal or other material that can be acid-etched or torn by hand.

[0174] In some other embodiments, the electron excitation layer 121 is prepared by a wet transfer method. The preparation method includes: directly preparing zero-dimensional materials, one-dimensional materials or two-dimensional materials in a solution and floating them on the liquid surface, making the bottom wall surface h1 of the light leakage notch h contact the zero-dimensional materials, one-dimensional materials or two-dimensional materials on the liquid surface, and drying the zero-dimensional materials, one-dimensional materials and / or two-dimensional materials on the bottom wall surface h1 of the light leakage notch h.

[0175] In still some other embodiments, the electron excitation layer 121 is prepared by a direct growth method. The preparation method includes: directly preparing the electron excitation layer 121 on the bottom wall surface h1 of the light leakage notch h by at least one of chemical vapor deposition, physical vapor deposition, molecular beam epitaxy and liquid filling.

[0176] Optionally, before or after forming the electron emission layer 120 on the bottom wall surface h1 of the light leakage notch h, the preparation method of the electron source 100 further includes:

[0177] S230. Form a conductive connection layer 130 on the bottom wall surface h1 of the light leakage notch h so that the conductive connection layer 130 overlaps with the electron excitation layer 121.

[0178] That is to say, the conductive connection layer 130 can be formed first, and then the electron excitation layer 121 can be formed; or the electron excitation layer 121 can be formed first, and then the conductive connection layer 130 can be formed; as long as the electron excitation layer 121 and the conductive connection layer 130 are electrically connected to each other, in this way, electrons can be supplied to the electron excitation layer 121 through the conductive connection layer 130, which is beneficial to the continuous emission of electrons from the electron excitation layer 121 under the excitation of laser light.

[0179] Optionally, a conductive connection layer 130 is formed on the bottom wall surface h1 of the light leakage gap h so that the conductive connection layer 130 overlaps with the electron excitation layer 121, specifically including:

[0180] S231. A core protection layer is formed on the bottom wall surface h1 of the light leakage gap h, and the core protection layer projects on the bottom wall surface h1 to cover the projection of the core 111 on the bottom wall surface h1.

[0181] It can be that the core protection layer directly covers the core 111 of the optical fiber 110, or it can be that the core protection layer indirectly covers the core 111 of the optical fiber 110, and no specific limitation is made here.

[0182] Optionally, the polymer microsphere solution can be coated on the bottom wall surface h1 of the light leakage gap h to form the above-mentioned core protection layer. Exemplarily, the polymer microsphere solution is a polymethyl methacrylate suspension.

[0183] S232. A conductive material layer covering the core protection layer is formed on the optical fiber 110.

[0184] The conductive material layer can be formed by evaporation coating. Specifically, a metal evaporation coating device can be used to form the conductive material layer on the optical fiber 110.

[0185] S233. The core protection layer and the part of the conductive material layer provided on the core protection layer are removed to form the conductive connection layer 130.

[0186] Optionally, a solvent that can dissolve the core protection layer and does not interact with the conductive material layer can be used to remove the core protection layer. Specifically, the bottom wall surface h1 of the light leakage gap h can be soaked in acetone so that the core protection layer (polymer microspheres) is dissolved, and the part of the conductive material layer provided on the core protection layer (part of the metal coating) is peeled off to obtain the conductive connection layer 130.

[0187] It can be understood that the core protection layer can be used to stagger the projection of the conductive connection layer 130 on the bottom wall surface h1 from the projection of the core 111 of the optical fiber 110 on the bottom wall surface h1, so that the laser transmitted in the core 111 of the optical fiber 110 can better interact with the electron excitation layer 121 provided on the bottom wall surface h1 of the light leakage gap h.

[0188] In some embodiments, the bottom wall surface h1 of the light leakage notch h is configured as a plane. The step S220 of forming the electron emission layer 120 on the bottom wall surface h1 of the light leakage notch h specifically includes the following steps. Specifically, the specific steps of transferring the electron excitation layer 121 on the temporary substrate 20 to the bottom wall surface h1 of the light leakage notch h are as follows:

[0189] S221. Set the electron excitation layer 121 and the bottom wall surface h1 of the light leakage notch h opposite to each other and parallel to each other along the first direction F1.

[0190] Specifically, observe the bottom wall surface h1 of the light leakage notch h and the electron excitation layer 121 under a microscope, and set the electron excitation layer 121 and the bottom wall surface h1 of the light leakage notch h opposite to each other and parallel to each other along the first direction F1, and make the center connection line of the two extend along the first direction F1.

[0191] S222. Drive the optical fiber 110 to move along the first direction F1 to contact the electron excitation layer 121.

[0192] S223. Make the electron excitation layer 121 adhere to the bottom wall surface h1 of the light leakage notch h at a preset temperature.

[0193] In this way, the center of the electron excitation layer 121 can be aligned with the bottom wall surface h1 of the light leakage notch h by using a microscope, and the two are adhered to each other at a certain temperature, so that the electron excitation layer 121 and the bottom wall surface h1 of the light leakage notch h can be closely adhered under the action of van der Waals force, improving the bonding fastness of the electron excitation layer 121 on the optical fiber 110, and also being beneficial to the projection of the electron excitation layer 121 on the bottom wall surface h1 to cover the projection of the fiber core 111 on the bottom wall surface h1, so that the laser transmitted by the fiber core 111 can better interact with the electron excitation layer 121.

[0194] In some specific embodiments, the step S220 of forming the electron emission layer 120 on the bottom wall surface h1 of the light leakage notch h specifically includes the following steps. Specifically, the specific steps of transferring the electron excitation layer 121 on the temporary substrate 20 to the bottom wall surface h1 of the light leakage notch h are as follows:

[0195] S2201. Stick an annular heating sheet 40 on the back of the perforated glass slide 30 of the microscope, fix the temporary substrate 20 with the electron excitation layer 121 on the bottom side of the annular heating sheet 40 (the temporary substrate 20 can be fixed on the bottom side of the annular heating sheet 40 by an adhesive fixing method), and make the electron excitation layer 121 on the temporary substrate 20 face down, and fix the optical fiber 110 below the electron excitation layer 121 (such as Figure 10As shown, the central axes of the objective lens of the microscope, the perforated slide 30, the annular heating sheet 40, and the electron excitation layer 121 coincide, and intersect at the central axis of the fiber core 111. The objective lens of the microscope, the perforated slide 30, the annular heating sheet 40, the electron excitation layer 121, and the optical fiber 110 are arranged in sequence from top to bottom.

[0196] Optionally, a fixture can be used to fix the optical fiber 110 on the moving platform, and the bottom wall surface h1 of the light leakage notch h is arranged upward. The moving platform is used to adjust the position of the optical fiber 110 along the first direction F1, and to adjust the angle of the bottom wall surface h1 of the light leakage notch h relative to the horizontal plane to make it horizontally set.

[0197] Optionally, the fixture can be a pneumatic gripper or an electric gripper.

[0198] Optionally, the moving platform can be a six-degree-of-freedom platform. The moving platform can also include a linear drive mechanism and a rotary drive mechanism connected to the linear drive mechanism. The output end of the rotary drive mechanism is connected to the fixture to drive the fixture and the optical fiber 110 clamped by the fixture to rotate around an axis parallel to the horizontal plane, so that the bottom wall surface h1 of the light leakage notch h is horizontally set. The linear drive mechanism is used to drive the rotary drive mechanism, the fixture, and the optical fiber 110 to move along the first direction F1.

[0199] Among them, the linear drive mechanism can be a motor or a cylinder, and the rotary drive mechanism can be a motor or a rotary cylinder.

[0200] S2202. Observe the bottom wall surface h1 of the light leakage notch h and the electron excitation layer 121 under the microscope, and make the electron excitation layer 121 and the bottom wall surface h1 of the light leakage notch h relatively arranged and parallel to each other along the first direction F1, and make the center connection line of the two extend along the first direction F1.

[0201] The center alignment of the bottom wall surface h1 of the light leakage notch h and the electron excitation layer 121 can be completed with the aid of a microscope.

[0202] S2203. Connect the annular heating sheet 40 to an external power supply to apply a first preset voltage to the annular heating sheet 40, and preheat the electron excitation layer 121 on the temporary substrate 20 (heat to the preheating temperature), which is beneficial to make the electron excitation layer 121 more flat.

[0203] Optionally, the first preset voltage is 1v - 1.5v, and the preheating temperature is 50 - 60°C.

[0204] S2204. Drive the optical fiber 110 to move along the first direction F1 to contact the electron excitation layer 121. It can make the bottom wall surface h1 of the light leakage notch h and the electron excitation layer 121 contact to form Newton's rings.

[0205] S2205. Make the electron excitation layer 121 tightly attached to the bottom wall surface h1 of the light leakage gap h at a preset temperature, specifically including: applying a second preset voltage to the annular heating plate 40, and heating the electron excitation layer 121 on the temporary substrate 20 to a preset temperature, which is conducive to the electron excitation layer 121 being more tightly attached to the bottom wall surface h1 of the light leakage gap h.

[0206] Optionally, the second preset voltage is 2.5V-4V, and the preset temperature is 90-100°C.

[0207] S2206, removing the temporary substrate 20, which can be removed by melting heating combined with solvent immersion. Specifically, applying a third preset voltage to the annular heating plate 40, and heating the temporary substrate 20 to a melting temperature to melt it, it should be noted that the melting point of the electron excitation layer 121 is much higher than that of the temporary substrate 20.

[0208] Optionally, the third preset voltage is 5.5V-6V, and the melting temperature is 130-150°C.

[0209] After the electron excitation layer 121 is tightly arranged on the bottom wall h1 of the light leakage gap h, the part of the temporary substrate 20 in contact with the annular heating plate 40 can be melted by melting heating, and the electron excitation layer 121 can be separated from the annular heating plate 40, combined with the bottom wall h1 tightly attached to the light leakage gap h, so as to facilitate the subsequent removal of the temporary substrate 20 remaining on the electron excitation layer 121. The part of the temporary substrate 20 that is not in contact with the annular heating plate 40 is still retained on the electron excitation layer 121, and the optical fiber 110 can be removed from the fixture and the bottom wall h1 of the light leakage gap h can be immersed in acetone to dissolve the temporary substrate 20 remaining on the electron excitation layer 121, and completely remove the temporary substrate 20.

[0210] See also Figure 11 According to a third aspect of the present application, an electron gun 10 is provided. The electron gun 10 includes a housing, a grid 200, an anode 300 and an electron source 100 according to any one of the above embodiments.

[0211] The electron source 100 is fixed in a housing, and a grid 200 and an anode 300 are sequentially arranged on the electron emission side of the electron source 100 .

[0212] It should be noted that in the present application, the gate 200 is used to limit the shape of the electron beam, and the anode 300 is used to accelerate the electrons. When the electrons are excited and emitted from the electron source 100, they will interact with the electrostatic field established by the gate 200 and the space charge of the electrons themselves, forming an electron beam with a certain shape, passing through the second electron channel 210 of the gate 200 and the first electron channel 310 of the anode 300 to be emitted for use.

[0213] According to the fourth aspect of the present application, there is provided an application of the electron source 100 as in the first aspect. The application of the electron source 100 includes at least one of an electron microscope, an electron beam lithography machine, a free electron laser, an X-ray tube, an electron accelerator, an electron diffraction device, and a display.

[0214] The embodiments of the present invention will be described in detail below in conjunction with the embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions in the following embodiments, the guidance given in the present invention is preferably referred to, and it can also be in accordance with the experimental manuals or conventional conditions in the art, or in accordance with the conditions recommended by the manufacturer, or refer to the experimental methods known in the art.

[0215] Example 1

[0216] Please refer to Figure 12 , the optical fiber 110 is a single-mode optical fiber. The diameter of the core 111 of the optical fiber 110 is 8.2 μm, the diameter of the optical fiber 110 is 125 μm. The bottom wall surface h1 of the light leakage notch h is configured as a plane and extends along the extending direction of the optical fiber 110. The light leakage notch h also has a side wall surface h2 extending along the radial direction of the optical fiber. The wavelength of the laser transmitted in the optical fiber 110 is 1550 nm. Graphene with a thickness of 0.3 nm is grown on the bottom wall surface h1 of the light leakage notch h by CVD method, and then quantum dots are prepared on the surface of the graphene by CVD method to form an electron excitation layer 121. A conductive connection layer 130 is provided on the optical fiber 110, and the conductive connection layer 130 is electrically connected to the graphene to obtain the electron source 100. The conductive connection layer 130 includes 4 nm of titanium and 50 nm of gold laminated on the optical fiber 110.

[0217] Example 2

[0218] Please refer to Figure 1 , the optical fiber 110 is a single-mode optical fiber. The diameter of the core 111 of the optical fiber 110 is 8.2 μm, the diameter of the optical fiber 110 is 125 μm. The bottom wall surface h1 of the light leakage notch h is configured as a plane and extends along the extending direction of the optical fiber 110. The light leakage notch h also has a side wall surface h2 extending along the radial direction of the optical fiber. The wavelength of the laser transmitted in the optical fiber 110 is 1550 nm. A conductive connection layer 130 is formed on the optical fiber 110, and graphene with a thickness of 0.3 nm is grown on the bottom wall surface h1 of the light leakage notch h by CVD method to form an electron excitation layer 121, wherein the conductive connection layer 130 is electrically connected to the graphene to obtain the electron source 100. The conductive connection layer 130 includes 4 nm of titanium and 50 nm of gold laminated on the optical fiber 110.

[0219] Comparative Example 1

[0220] Prepare an electron source according to the structure of Example 1, except that the electron excitation layer 121 in Example 1 is replaced with a gold layer with a thickness of 100 nm, and the gold layer is prepared by deposition.

[0221] Comparative Example 2

[0222] Prepare an electron source according to the structure of Comparative Example 1, except that the electron excitation layer 121 in Comparative Example 1 is replaced with a gold layer with a thickness of 5 nm (the same thickness as the graphene).

[0223] As Figure 11 shown, assemble the electron sources prepared by the above examples and comparative examples into an electron gun. The electron gun further includes a housing, a grid 200, and an anode 300. Perform performance tests on the manufactured electron gun. The test results are as follows in the table:

[0224] Table 1

[0225] Number Stability Lifetime Working vacuum degree Example 1 3％ 1000h 10 Pa Example 2 3％ 1000h 10 Pa Comparative Example 1 10％ 100 h <![CDATA[10 -5 Pa]]> Comparative Example 2 20％ 20 h <![CDATA[10 -5 Pa]]>

[0226] Among them, stability refers to when the excitation power of the electron source is 50% or more of the damage power and the vacuum degree is 2×10 -5 Pa, continuously emit current for 1 hour. After removing the bad points, the ratio of the difference between the maximum current and the minimum current to the average current is the stability, and the stability can reflect the working stability of the electron source. Lifetime refers to when the excitation power of the electron source is 50% or more of the damage power and the vacuum degree is 2×10 -5 Pa, continuously emit current until the current decays to less than 10% of the initial value, which is defined as the lifetime. The working vacuum degree refers to when the excitation power of the electron source is 50% or more of the damage power, continuously emit current. The vacuum degree gradually increases until the current shows a rapid decay (the rapid decay is defined as the current decaying by more than 50% within 1 minute). The vacuum degree at this time is defined as the working vacuum degree. It can be seen from the above table that: the electron source of the present application has good stability, a long lifetime, and a good working vacuum degree.

[0227] It is found through testing that compared with the lifetime of the electron source prepared by the comparative example, the lifetime of the electron source prepared by Examples 1-2 is higher; compared with the stability of the electron source prepared by the comparative example, the stability of the electron source prepared by Examples 1-2 is better.

[0228] In summary, low-dimensional materials such as zero-dimensional materials, one-dimensional materials, and two-dimensional materials in this application have atomic-level dimensions. Electrons excited from low-dimensional materials can be emitted into a vacuum without passing through in-body transmission, making them very suitable for ultrafast electron sources with narrow pulse widths. Moreover, low-dimensional materials and different types of optical fibers can be directly integrated, bringing ultra-high stability and integration. In addition, low-dimensional materials have no dangling bonds, are stable, have a high melting point, and are not easily damaged, making them suitable for high-power-excited large-beam electron sources. When low-dimensional materials are integrated with a tip, a very sharp optical fiber tip can be obtained, which has large optical field and electric field enhancement factors and provides a large emission beam current. There are many combinations of low-dimensional materials, making them suitable for optoelectronic sources with various properties. Finally, the optoelectronic source with low-dimensional materials integrated with an optical fiber has significant advantages. The optical fiber can not only transmit laser light but also, as a carrier of low-dimensional materials, provide a stable excitation source with adjustable wavelength, polarization, and optical mode. It can be applied to different application scenarios, does not require a complex optical path, and has the characteristics of small volume and high integration. When integrated with other devices, it can achieve stable integration without cracking and transforming vacuum electronic devices.

[0229] In this application, since the size of the electron excitation layer 121 is on the nanometer scale, the process of in-body transmission of the excited electrons in the electron excitation layer 121 can be reduced, which is beneficial to improving the electron emission efficiency and emission power. Furthermore, an electron beam with ultra-short pulses can be realized by using this electron source 100. The electron source 100 in this application uses low-dimensional materials as the materials for emitting electrons. Because low-dimensional materials have a high optical nonlinear effect and discrete electron energy levels, the laser can better interact with the electron excitation layer 121 to produce energy resonance and excite the electrons in the electron excitation layer 121. These electrons are excited and detached into a vacuum to form an electron beam, and the electron beam tunneling and emitting from the electron excitation layer 121 has the characteristics of concentrated energy and small energy dispersion. In addition, the electron excitation layer 121 with a nanometer-scale thickness does not affect the transmission mode of the optical fiber 110, so that the transmission mode of the electron source 100 is mainly determined by the optical fiber, enabling the electrons emitted by the electron source 100 to be emitted efficiently along the extension direction of the optical fiber 110, which provides great convenience for controlling the transmission mode of the electron source 100. Moreover, this electron source 100 abandons the complex spatial light coupling structure set due to the introduction of external laser light, which is convenient to be assembled into the housing of the electron gun; it also abandons the high-magnification microscope set to solve the alignment problem of metal tips, which can reduce the process cost of the electron gun.

[0230] The technical features of the above embodiments can be combined arbitrarily. For the sake of brief description, 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, it should be considered as the scope recorded in this specification.

[0231] The above embodiments only represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patented application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. An electron source, characterized in that, Comprising: An optical fiber, including a core for transmitting laser light and a cladding layer wrapping the core; A light leakage notch is formed in the light-emitting end of the optical fiber along the radial direction of the optical fiber; And An electron emission layer is provided on the bottom wall surface of the light leakage notch, and the electron emission layer at least includes an electron excitation layer; the bottom wall surface of the light leakage notch is configured as a plane, and the projection of the electron excitation layer on the bottom wall surface covers the projection of the core on the bottom wall surface; Wherein, the electron excitation layer includes at least one of zero-dimensional materials, one-dimensional materials, and two-dimensional materials.

2. The electron source according to claim 1, wherein The bottom wall surface of the light leakage notch extends along the extending direction of the optical fiber.

3. The electron source according to claim 1, wherein The light leakage notch is provided in the cladding layer. Along the radial direction of the optical fiber, the maximum distance between the bottom wall surface of the light leakage notch and the core is less than or equal to a preset value.

4. The electron source according to claim 3, characterized in that, The preset value is D, where 0μm < D ≤ 3μm.

5. The electron source according to claim 1, wherein The bottom wall surface of the light leakage notch is spaced from the core, and the bottom wall surface of the light leakage notch is parallel to the tangent plane of the outer surface of the core; or The bottom wall surface of the light leakage notch is configured as a plane partially formed on the core.

6. The electron source according to claim 1, characterized in that, The thickness of the electron excitation layer is less than or equal to 50nm.

7. The electron source according to claim 1, wherein The axial direction of the one-dimensional material in the electron excitation layer forms an angle of 0 to 90° with the emission direction of the emitted laser light.

8. The electron source according to claim 1, characterized in that, The electron excitation layer includes at least two two-dimensional materials stacked in sequence along the laser emission direction; or, The electron excitation layer includes at least two two-dimensional materials with different materials connected to each other in the same plane.

9. The electron source according to claim 1, wherein The materials in the electron excitation layer include one-dimensional materials and zero-dimensional materials provided at the ends and / or sides of the one-dimensional materials.

10. The electron source according to claim 1, characterized in that, The electron excitation layer includes zero-dimensional materials and two-dimensional materials, and the zero-dimensional materials are provided on the surface of the two-dimensional materials.

11. The electron source according to claim 1, wherein, The electron excitation layer includes one-dimensional materials and two-dimensional materials, and the one-dimensional materials are provided on the surface of the two-dimensional materials.

12. The electron source according to any one of claims 1-11, characterized in that, The electron source further includes a conductive connection layer provided at least on the bottom wall surface of the light leakage notch, and the conductive connection layer is electrically connected to the electron excitation layer.

13. The electron source according to claim 12, characterized in that, The electron excitation layer includes a first part and a second part provided on the bottom wall surface of the light leakage notch and connected to each other; The projection of the first part on the bottom wall surface covers the projection of the core on the bottom wall surface; the second part is located on the periphery of the first part and is electrically connected to the conductive connection layer.

14. The electron source according to claim 13, characterized in that, The conductive connection layer includes a first conductive part provided on the bottom wall surface of the light leakage notch and a second conductive part connected to the first conductive part and provided on the circumferential side surface of the optical fiber; The first conductive part overlaps with the second part of the electron excitation layer.

15. The electron source according to claim 12, wherein The conductive connection layer includes a first metal layer and a second metal layer stacked; The adhesion of the first metal layer is greater than the adhesion of the second metal layer.

16. The electron source according to claim 12, characterized in that, The electron emission layer further includes an auxiliary layer, and the auxiliary layer is stacked on one side of the electron excitation layer close to the bottom wall surface of the light leakage notch; or, The auxiliary layer is stacked on one side of the electron excitation layer away from the bottom wall surface of the light leakage notch.

17. The electron source according to claim 16, wherein The auxiliary layer satisfies at least one of the following conditions: (1) The auxiliary layer includes at least one of a conductive support layer and a heat dissipation support layer; (2) The thickness of the auxiliary layer is 0.1 nm to 10 nm, and the light transmittance is 10% or more.

18. The electron source according to claim 16, wherein The auxiliary layer includes a conductive support layer, and the conductive support layer is electrically connected to the conductive connection layer.

19. The electron source according to claim 16, characterized in that, The auxiliary layer includes a conductive support layer, the material of the conductive support layer includes a conductive metal, the laser wavelength in the optical fiber is 200 nm to 10 μm, the pulse power is 1 nw to 1 w, and the repetition frequency is 0 Hz to 10 GHz.

20. A method for preparing an electron source, characterized in that, Comprising: Providing an optical fiber; wherein, the optical fiber includes a core for transmitting laser and a cladding layer wrapped around the core; a light leakage notch is formed along the radial direction of the light output end of the optical fiber; Forming an electron emission layer on the bottom wall surface of the light leakage notch; Wherein, the electron emission layer at least includes an electron excitation layer, the bottom wall surface of the light leakage notch is configured as a plane, and the projection of the electron excitation layer on the bottom wall surface covers the projection of the core on the bottom wall surface; the electron excitation layer includes at least one of a zero-dimensional material, a one-dimensional material, and a two-dimensional material.

21. The method for preparing an electron source according to claim 20, wherein Before or after forming the electron emission layer on the bottom wall surface of the light leakage notch, the preparation method of the electron source further includes: Forming a conductive connection layer on the bottom wall surface of the light leakage notch so that the conductive connection layer overlaps with the electron excitation layer.

22. The method for preparing an electron source according to claim 21, wherein, Forming the conductive connection layer on the bottom wall surface of the light leakage notch so that the conductive connection layer overlaps with the electron excitation layer specifically includes: Forming a core protection layer on the bottom wall surface of the light leakage notch, wherein the projection of the core protection layer on the bottom wall surface covers the projection of the core on the bottom wall surface; Forming a conductive material layer covering the core protection layer on the optical fiber; Removing the core protection layer and the part of the conductive material layer provided on the core protection layer to form the conductive connection layer.

23. The method for preparing an electron source according to claim 20, wherein Forming the electron emission layer on the bottom wall surface of the light leakage notch specifically includes: Setting the electron excitation layer and the bottom wall surface of the light leakage notch opposite to each other and parallel to each other in a first direction; Driving the optical fiber to move in the first direction to contact the electron excitation layer; Bonding the electron excitation layer to the bottom wall surface of the light leakage notch at a preset temperature.

24. An electron gun, characterized in that, The electron gun includes a housing, a grid, an anode, and the electron source according to any one of claims 1-19; The electron source is fixed in the housing, and the grid and the anode are sequentially arranged on the electron emission side of the electron source.

25. Use of the electron source according to any one of claims 1-19, characterized in that, The applications of the electron source include at least one of an electron microscope, an electron beam lithography machine, a free electron laser, an X-ray tube, an electron accelerator, an electron diffraction device, and a display.

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