CN117116727A - Photoelectron source based on dielectric material system - Google Patents
Photoelectron source based on dielectric material system Download PDFInfo
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- CN117116727A CN117116727A CN202310901651.7A CN202310901651A CN117116727A CN 117116727 A CN117116727 A CN 117116727A CN 202310901651 A CN202310901651 A CN 202310901651A CN 117116727 A CN117116727 A CN 117116727A
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- 239000003989 dielectric material Substances 0.000 title claims abstract description 44
- 239000002086 nanomaterial Substances 0.000 claims abstract description 23
- 239000000758 substrate Substances 0.000 claims abstract description 23
- 230000005284 excitation Effects 0.000 claims abstract description 20
- 230000003287 optical effect Effects 0.000 claims abstract description 10
- 230000008878 coupling Effects 0.000 claims abstract description 3
- 238000010168 coupling process Methods 0.000 claims abstract description 3
- 238000005859 coupling reaction Methods 0.000 claims abstract description 3
- 229910052582 BN Inorganic materials 0.000 claims description 29
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims description 29
- 239000000463 material Substances 0.000 claims description 27
- 230000005693 optoelectronics Effects 0.000 claims description 16
- 230000010287 polarization Effects 0.000 claims description 12
- 239000011521 glass Substances 0.000 claims description 8
- 238000010894 electron beam technology Methods 0.000 claims description 7
- 239000004065 semiconductor Substances 0.000 claims description 7
- 239000010453 quartz Substances 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 239000004020 conductor Substances 0.000 claims description 3
- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 claims description 3
- 229910001195 gallium oxide Inorganic materials 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 229910002601 GaN Inorganic materials 0.000 claims description 2
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 claims description 2
- 230000008859 change Effects 0.000 claims description 2
- 238000003260 vortexing Methods 0.000 claims 1
- 238000002003 electron diffraction Methods 0.000 abstract description 6
- 239000010410 layer Substances 0.000 description 26
- 230000001105 regulatory effect Effects 0.000 description 11
- 230000001276 controlling effect Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000005684 electric field Effects 0.000 description 2
- 238000001493 electron microscopy Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 2
- 238000010884 ion-beam technique Methods 0.000 description 2
- 239000012780 transparent material Substances 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- TXONVAMTMVNDJZ-UHFFFAOYSA-N [O-2].[Zr+4].[W+4].[O-2].[O-2].[O-2] Chemical compound [O-2].[Zr+4].[W+4].[O-2].[O-2].[O-2] TXONVAMTMVNDJZ-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000012792 core layer Substances 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
- H01J37/06—Electron sources; Electron guns
- H01J37/075—Electron guns using thermionic emission from cathodes heated by particle bombardment or by irradiation, e.g. by laser
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/34—Photo-emissive cathodes
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
Abstract
The invention discloses a photoelectron source based on a dielectric material system, which is characterized by comprising an excitation light source, a dielectric material layer, a substrate layer and a conductive layer, wherein the dielectric material layer, the substrate layer and the conductive layer are positioned in a vacuum cavity; a conducting layer and a dielectric material layer serving as a waveguide are sequentially arranged on the substrate layer; the excitation light source is used for generating laser to be incident to the dielectric material layer; the micro-nano structure is prepared on the dielectric material layer and is used for converging and coupling laser incident to the edge of the dielectric material layer from the edge to the central area of the dielectric material layer, and the local optical field modes exceeding the diffraction limit are formed in the central area by focusing through interference superposition among waveguide modes in different directions, and the distribution area of the local optical field modes is used as a working area for generating electrons of the photoelectron source, namely an emission area of the photoelectron source. The invention forms a planar photoelectron source with an ultra-small emission area of tens of nanometers, a smaller emission angle and narrower electron broadening, and provides great help for the application of an ultra-fast electron microscope and ultra-fast electron diffraction.
Description
Technical Field
The invention relates to a photoelectron source or photocathode technology, in particular to a novel photoelectron source of a dielectric material system.
Background
Electron sources, or electron guns or cathodes, are important components of various electron microscopes. The electron sources can be classified into thermal emission sources, field emission sources, and photoelectron sources (or photocathodes) according to excitation. The thermal emission and field emission sources enable material electrons to directly escape from the surface of a sample through thermal effect or high-voltage electric field; the photoelectron source is formed by laser incident on the electron gun, and electrons on the surface of the electron gun material escape from the surface of the sample against work function through the processes of photoelectric effect and the like. The most prominent application of the photoelectron source is as an ultrafast electron source of various ultrafast electron microscopic imaging and ultrafast electron diffraction apparatuses. The principle is that an electron source is excited by ultra-short pulses such as femtosecond laser and the like to generate ultra-short electronic pulses, so that various ultra-fast physical and chemical processes in a sample are detected. The specific scheme is as follows: the ultra-short pulse laser generated by a laser is firstly split, one beam of light is directly incident on a sample and excites a series of photophysical and photochemical dynamic processes in the material; the other beam of light is incident on the electron gun to generate ultra-short electron pulse and is transmitted to the sample, and the evolution of the dynamic process inside the material can be detected by changing the time delay between the electron pulse and the first beam of incident light, and the evolution is specifically reflected to the change of electron imaging or electron diffraction spots at different moments, and the corresponding instrument is called an ultra-fast electron microscope (Ultrafast electron microscopy, UEM) and an ultra-fast electron diffraction (Ultrafast electron diffraction, UED).
Currently, photoelectronic sources can be classified into planar photocathodes and tip photocathodes according to design structures. Common materials for planar photocathodes include gold, silver, copper, lanthanum hexaboride (LaB 6), etc., and common materials for tip photocathodes include tungsten, tungsten-zirconium oxide (W-ZrO), tantalum (Ta), etc. The planar photocathode has the advantages of small electron emission angle, larger source area, generally more than tens of micrometers, and the tip photocathode has the advantages of smaller source area, optimally up to tens of nanometers, and larger electron emission angle influenced by tip effect. In order to increase the coherence of electrons, an ideal photoelectron source should have both a small emission area and emission angle and a relatively small energy spread of electrons. It would therefore be very helpful to the practice to design a new type of photoelectron source to have both of the above advantages, and the present invention would provide an effective solution to this problem.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention aims to provide a novel photoelectron source based on a dielectric material system, which is based on a novel low-dimensional wide forbidden band semiconductor material hexagonal boron nitride (hBN), and forms the novel photoelectron source with ultra-small emission area, small emission angle and narrow electron energy distribution through novel micro-nano structure design.
The technical scheme of the invention is as follows:
an optoelectronic source based on a dielectric material system is characterized by comprising an excitation light source, a dielectric material layer, a substrate layer and a conductive layer, wherein the dielectric material layer, the substrate layer and the conductive layer are positioned in a vacuum cavity;
the conducting layer and the dielectric material layer serving as the waveguide are sequentially arranged on the substrate layer;
the excitation light source is used for generating laser to be incident to the dielectric material layer;
the micro-nano structure is prepared on the dielectric material layer and is used for converging and coupling laser incident to the edge of the dielectric material layer from the edge to the central area of the dielectric material layer, and a local light field mode exceeding the diffraction limit is formed in the central area by focusing through interference superposition among waveguide modes in different directions, and the distribution area of the local light field mode is used as a working area for generating electrons of the photoelectron source, namely an emission area of the photoelectron source.
Further, the material of the dielectric material layer is a wide bandgap semiconductor material with a bandgap greater than 3 eV.
Further, the dielectric material is hexagonal boron nitride, gallium nitride or gallium oxide.
Further, the distribution of the local light field modes is regulated and controlled by controlling the laser wavelength, polarization or vortex generated by the excitation light source, so that the spatial mode distribution of the electronic pulse emitted by the emission area is regulated and controlled.
Further, the distribution of the local light field mode is changed by controlling the polarization of the laser light, so that the transverse distribution of the electronic pulse emitted by the emission area is regulated and controlled.
Further, by controlling the wavelength of the laser, the laser is focused to a single point in the central area, so that the electron beam emitted from the emission area is regulated to be in solid distribution.
Further, by controlling the wavelength of the laser, the laser is focused into a circular ring in the central area, so that the electron beam emitted from the emission area is regulated and controlled to be distributed annularly.
Further, the substrate layer is made of glass or quartz; the material of the conductive layer is transparent conductive material.
Further, the laser generated by the excitation light source is normally incident to the dielectric material layer; or laser generated by the excitation light source is back-incident to the dielectric material layer through the substrate layer and the conductive layer.
Further, the micro-nano structure is a circular groove structure, an Archimedes spiral structure or a ring grating structure required by an photoelectron source.
The photoelectron source based on the dielectric material system comprises: selecting a dielectric material, designing a micro-nano structure and integrally configuring an photoelectron source; the dielectric material is selected from wide bandgap semiconductor materials (band gap is larger than 3 eV), such as hexagonal boron nitride, gallium oxide and other wide bandgap semiconductor materials, wherein the novel low-dimensional material hexagonal boron nitride is one of excellent candidate materials. Hexagonal boron nitride has a wide band gap of up to 6eV, so that the hexagonal boron nitride has a wide transparent window from infrared to deep ultraviolet, and a very large range is provided for the selection of the wavelength of an excitation light source. Meanwhile, the hexagonal boron nitride has extremely high refractive index in an optical band, and the refractive index is more than 2.0 from infrared to deep ultraviolet, so that a necessary condition is provided for the design of a micro-nano optical structure. In addition, hexagonal boron nitride is a van der Waals type layered material with an atomically flat surface, which is advantageous for forming small angle photoelectron exits. The design of the photoelectron source will be described below using a hexagonal boron nitride material as an example, but the practical application is not limited to this material. The micro-nano structure design is to form an optical field local area exceeding the diffraction limit by designing a micro-nano structure based on a dielectric slab waveguide, so that an ultra-small size electron source emission area of tens of nanometers is formed. Meanwhile, through the micro-nano structure design and the combination of parameters such as polarization, vortex and the like of incident light, the spatial mode distribution of the intensity of the photoelectron source and the like can be regulated and controlled. The overall configuration of the photoelectron source is provided by combining material selection, structural design and excitation light source parameters.
The dielectric material selection includes: the core material is hexagonal boron nitride and other wide band gap semiconductor material, the support material is glass or quartz substrate, and the conducting layer material is Indium Tin Oxide (ITO) and other transparent conducting material.
The micro-nano structure design comprises: firstly, hexagonal boron nitride material with the thickness of tens of nanometers to hundreds of nanometers is transferred or grown on a glass or quartz substrate with a conducting layer on the upper surface, so that a three-layer dielectric slab waveguide structure of a vacuum-hexagonal boron nitride-substrate is formed, the hexagonal boron nitride is used as a core layer of a waveguide due to the higher refractive index, and the whole structure works in a vacuum cavity. And then preparing the needed micro-nano structure such as an annular groove structure, an Archimedes spiral structure and an annular grating structure on the hexagonal boron nitride through micro-nano processing technologies such as focused ion beam etching, electron beam exposure or photoetching. The structure is characterized in that in order to couple incident light into a hexagonal boron nitride dielectric waveguide, normal incidence laser is coupled into a slab waveguide through the edge of the structure, and then propagates and converges from the edge to a central area, and through interference superposition among waveguide modes in different directions, local light field modes exceeding diffraction limit are formed in the central area of the structure in a focusing mode, and the local fields simultaneously have stronger light field intensity than the incident light, and the local light field mode distribution areas are working areas for generating electrons of an photoelectron source and correspond to the emission areas of the photoelectron source. Meanwhile, the distribution of the local light field modes can be regulated and controlled by controlling parameters such as wavelength, polarization and vortex of incident light, so that the spatial mode distribution of emergent electronic pulses is regulated and controlled, for example, the distribution of the local light field modes on the surface of hexagonal boron nitride can be changed by controlling polarization of the incident light, and the transverse distribution of the emergent electronic pulses is regulated and controlled; by changing the incident wavelength, the central region can be a focused single point or a circular ring (the center is a dark point), so that the emergent electron beam is in solid distribution or annular distribution.
The overall configuration of the photoelectron source comprises: and (3) the ultra-short pulse laser is incident into a hexagonal boron nitride micro-nano structure area, then the micro-nano structure couples incident light into a hexagonal boron nitride dielectric waveguide, and a local optical field mode exceeding the diffraction limit is formed by focusing in the central area of the structure. The local light field mode has strong near field intensity, and can effectively excite photoelectron emission through photoelectric effect, so that a planar photoelectron source with ultra-small emission area is formed. The incidence direction of the ultra-short pulse laser can be normal incidence or reverse incidence. Because the selected substrate and the wide forbidden band semiconductor are both high transparent materials, the incidence of laser from the back and the emission of electrons from the front can be realized, which provides great convenience for the design and practical work of the photoelectron source. The laser wavelength is selected from the near infrared to the ultraviolet band. The excitation light wavelength, polarization and vortex parameters can regulate and control the spatial distribution of photoelectron source modes. The incident light of the visible light wave band is selected, so that two-photon or multi-photon light emission can be realized, and the small emission angle and narrow electron energy distribution are realized at the same time. Thus, an ideal photoelectron source with ultra-small emission area, small emission angle and narrow electron broadening is formed, and the characteristics of the electronic pulse can be conveniently controlled by light field regulation. Meanwhile, the design supports the generation of an ultra-fast photoelectron source, and ultra-short electronic pulses can be generated by adopting ultra-short pulse excitation.
The invention has the advantages that:
the invention provides a novel photoelectron source based on a medium system, which combines the advantages of a tip type photocathode with the advantages of a planar photocathode through micro-nano structural design to form a planar photoelectron source with ultra-small emission area of tens of nanometers, smaller emission angle and narrower electron broadening; meanwhile, the spatial mode distribution of the electronic pulse can be conveniently regulated and controlled through parameters such as excitation light wavelength, polarization, vortex and the like, and the photoelectron source can support back incidence and ultra-fast photoelectron pulse generation. These advantages provide great assistance to applications of ultrafast electron microscopy and ultrafast electron diffraction.
Drawings
FIG. 1 is a general design of an optoelectronic source of the present invention based on a dielectric material system.
FIG. 2 is an example of a design of the micro-nano structure required for the photoelectron source of the present invention;
(a) is a circular groove structure carved on the hBN, (b) is an Archimedes spiral structure carved on the hBN, and (c) is a circular grating structure carved on the hBN.
FIG. 3 is a representative example of the spatial distribution, emission angle, and energy distribution of an optoelectronic source in accordance with the present invention;
(a) is the real space distribution size, (b) is the momentum space distribution, and (c) is the energy distribution range.
Detailed Description
The invention will be further elucidated by means of specific embodiments in conjunction with the accompanying drawings.
As shown in fig. 1, the photoelectron source based on the dielectric material system of the present embodiment generally includes: excitation light, dielectric material and micro-nano structure. The incident light can be selected as laser with wavelengths from near infrared to ultraviolet, such as femtosecond laser with 400-450nm blue light wave band, the direction of the incident light can be normal incidence or reverse incidence, and the distribution of the incident light mode can be plane light with linear polarization, circular polarization or vortex rotation. The wavelength, polarization and vortex mode of the incident light can be controlled by the optical elements of the external light path. The materials constituting the photoelectron source are hexagonal boron nitride, indium Tin Oxide (ITO) conductive layer and glass substrate. The hexagonal boron nitride is provided with a micro-nano structure prepared by a micro-nano processing technology so as to form photoelectron sources with ultra-small emission areas of tens of nanometers or form photoelectron sources distributed in a specific space mode. Besides controlling the distribution of the electronic pulse modes through the micro-nano structure, the distribution of the electronic pulse modes can be regulated and controlled through the wavelength, polarization and vortex modes of incident light.
FIG. 1 is a schematic diagram of an overall design of a photoelectron source based on a dielectric material system, wherein the incident laser can be back-incident or normal-incident, and the hexagonal boron nitride is engraved with a required micro-nano structure to generate a light field local area, so that a photoelectron source with ultra-small emission area and specific spatial mode distribution is generated.
As shown in fig. 2, examples of micro-nanostructure designs required for an optoelectronic source include: the device comprises a hexagonal boron nitride slab waveguide structure, an etched micro-nano structure, an ITO conductive layer and a glass substrate. Examples of etched structures include: a circular groove structure, an Archimedes spiral structure and a ring grating structure. The structure body is a slab waveguide structure formed by placing hexagonal boron nitride on a glass substrate, and an ITO conductive layer with the thickness of about 10nm is plated on the surface of the substrate. The hexagonal boron nitride thickness is selected to be moderate to support the TE (transverse electric field) mode of the fundamental mode, for example, for 400-450nm incident light, the hexagonal boron nitride thickness H is preferably 50-100 nm. The thickness of the ITO is as thin as possible to reduce absorption loss of the ITO to the waveguide mode, and the substrate is selected from a glass substrate or other transparent materials with low refractive index. By means of micro-nano processing technology such as focused ion beam etching, electron beam exposure and the like, an etched micro-nano structure is formed on hexagonal boron nitride, incident light can be coupled, a local light field mode is formed, and therefore photoelectron sources with specific spatial distribution are generated.
FIG. 2 is a schematic illustration of the micro-nano structure required for an optoelectronic source. FIG. 2 (a) shows a structure of a circular groove engraved on hexagonal boron nitride (hBN), the slit is a circular groove, wherein r is 0 The inner diameter of the circular ring is W is the width of the circular ring groove, and H is the thickness of the hBN. Fig. 2 (b) shows an archimedes spiral structure engraved on hBN, where m is the number of spiral lobes and θ is the corresponding angle. Fig. 2 (c) shows a ring grating structure engraved on hBN, where P is the grating period.
The annular groove structure can form an optical field local mode with a size of tens of nanometers, so that an ultra-small photoelectron source emission area with a size of tens of nanometers is formed. For the wave band of 400-450nm, the two-photon light emission process is needed to overcome the work function of hexagonal boron nitride to generate photoelectron emission, so that the photoelectron source has the following functionsProviding ultra-small emission angles and narrower electron broadening. Such as: as shown in FIG. 3, a 65nm thick hexagonal boron nitride is used, radius r 0 The annular groove structure with the groove width W of about 20 mu m and about 200nm is characterized in that femtosecond laser with the center wavelength of 410nm is used for front incidence excitation, and the actual photoelectron source index can reach the photoelectron source emission area of 75nm,Momentum space distribution of-0.65 eV. It is noted that the radius r of the annular groove 0 And the width W needs to be designed to form a local mode as strong as possible, wherein the radius is better than an integral multiple of the effective wavelength of the waveguide mode, and the width W is better than 1/3-1/2 of the wavelength of the incident light.
Fig. 3 shows a typical example of the spatial distribution, emission angle and energy distribution of the photoelectron source, wherein fig. 3 (a) shows the real spatial distribution size, fig. 3 (b) shows the momentum spatial distribution, and fig. 3 (c) shows the energy distribution range.
In addition, the Archimedes spiral structure can form complicated optical field local mode with annular distribution, and the electronic pulse with unique spatial distribution can be generated by controlling the number m of the spiral lobes. The annular grating structure can greatly enhance the intensity of a focused local mode through interference superposition of light coupled by different annular grooves, and the local light field intensity can be improved by more than 3 orders of magnitude relative to the incident light by controlling the period P of the annular grooves and the number of the grooves, so that an ultra-small-size and ultra-high-brightness photoelectron source is formed.
Finally, it should be noted that the examples are disclosed for the purpose of aiding in the further understanding of the present invention, but those skilled in the art will appreciate that: various alternatives and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the invention should not be limited to the disclosed embodiments, but rather the scope of the invention is defined by the appended claims.
Claims (10)
1. An optoelectronic source based on a dielectric material system is characterized by comprising an excitation light source, a dielectric material layer, a substrate layer and a conductive layer, wherein the dielectric material layer, the substrate layer and the conductive layer are positioned in a vacuum cavity;
the conducting layer and the dielectric material layer serving as the waveguide are sequentially arranged on the substrate layer;
the excitation light source is used for generating laser to be incident to the dielectric material layer;
the micro-nano structure is prepared on the dielectric material layer and is used for converging and coupling laser incident to the edge of the dielectric material layer from the edge to the central area of the dielectric material layer, and a local light field mode exceeding the diffraction limit is formed in the central area by focusing through interference superposition among waveguide modes in different directions, and the distribution area of the local light field mode is used as a working area for generating electrons of the photoelectron source, namely an emission area of the photoelectron source.
2. The optoelectronic source of claim 1 wherein the material of the dielectric material layer is a wide bandgap semiconductor material having a bandgap greater than 3 eV.
3. The optoelectronic source of claim 2 wherein the dielectric material is hexagonal boron nitride, gallium nitride or gallium oxide.
4. An optoelectronic source as claimed in claim 1, 2 or 3 wherein the spatial mode distribution of the electronic pulses exiting the emission region is modulated by controlling the laser wavelength, polarisation or vortexing produced by the excitation light source to modulate the distribution of the local optical field modes.
5. The optoelectronic source of claim 4 wherein the lateral distribution of the electron pulses exiting the emission region is modulated by controlling the polarization of the laser light to change the distribution of the localized light field modes.
6. The optoelectronic source of claim 4 wherein the electron beam exiting the emitter region is modulated to a solid distribution by controlling the wavelength of the laser to focus to a single point at the central region.
7. The optoelectronic source of claim 4 wherein the electron beam exiting the emitter region is modulated to a circular distribution by controlling the wavelength of the laser to focus it into a circular ring in the central region.
8. An optoelectronic source according to claim 1, 2 or 3 wherein the material of the substrate layer is glass or quartz; the material of the conductive layer is transparent conductive material.
9. The optoelectronic source of claim 8 wherein the laser light generated by the excitation light source is normal incidence to the dielectric material layer; or laser generated by the excitation light source is back-incident to the dielectric material layer through the substrate layer and the conductive layer.
10. The optoelectronic source of claim 1, 2 or 3 wherein the micro-nano structure is a circular groove structure, an archimedes spiral structure or a ring grating structure required for the optoelectronic source.
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| CN202310901651.7A CN117116727A (en) | 2023-07-21 | 2023-07-21 | Photoelectron source based on dielectric material system |
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| CN202310901651.7A CN117116727A (en) | 2023-07-21 | 2023-07-21 | Photoelectron source based on dielectric material system |
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