Electromagnetic wave detection device

Abstract

This electromagnetic wave detection device (1) comprises a metasurface (S), insulating layers (81, 82, 83), a plurality of electrode parts (71, 72, 73), an electron multiplication unit (40), and a detection unit. The metasurface (S) includes a plurality of antenna elements (61) that emit electrons (P) in response to the incidence of electromagnetic waves (L). The insulating layers (81, 82, 83) are disposed on the metasurface (S) and have a plurality of holes (HL) at positions corresponding to the plurality of antenna elements (61), respectively. The electrons (P) emitted from the plurality of antenna elements (61) pass through the plurality of holes (HL). The plurality of electrode parts (71, 72, 73) are disposed on the insulating layers (81, 82, 83) at positions corresponding to the plurality of holes (HL), respectively. According to the electrons (P) that have passed through the plurality of holes (HL), the electron multiplication unit (40) multiplies the electrons (P) using a dynode (42). The detection unit (40) detects the electrons (P) multiplied by the electron multiplication unit.

Description

Electromagnetic wave detection device

[0001] The present disclosure relates to an electromagnetic wave detection device.

[0002] An electromagnetic wave detection device including a metasurface that emits electrons in response to incidence of electromagnetic waves is known (for example, Patent Document 1). This electromagnetic wave detection device includes an electron multiplier section that multiplies electrons, and a detection section that detects the electrons multiplied by the electron multiplier section.

[0003] Japanese Patent Publication No. 2023-512566

[0004] Electrons emitted from the metasurface enter the electron multiplier section, whereby the electrons are multiplied by the electron multiplier section, and the multiplied electrons are detected by the detection section. As a result, the electromagnetic wave incident on the metasurface is detected. However, electrons emitted from the metasurface may move in the surface direction of the metasurface without reaching the electron multiplier section. In this case, it is difficult for the detection section to detect the electrons, and it is difficult to detect the electromagnetic wave incident on the metasurface. Therefore, if the electrons emitted from the metasurface can easily reach the electron multiplier section, the detection accuracy of the electromagnetic wave incident on the metasurface is improved.

[0005] One aspect of the present disclosure aims to provide an electromagnetic wave detection device that can improve the detection accuracy of electromagnetic waves.

[0006] An electromagnetic wave detection device according to one aspect of the present disclosure is [1] "An electromagnetic wave detection device comprising: a metasurface including a plurality of antenna elements that emit electrons in response to incidence of electromagnetic waves; an insulating layer disposed on the metasurface and having a plurality of holes through which the electrons pass at positions corresponding to each of the plurality of antenna elements; a plurality of electrode sections disposed on the insulating layer at positions corresponding to each of the plurality of holes; an electron multiplier section that multiplies electrons in response to the electrons that have passed through the plurality of holes; and a detection section that detects the electrons multiplied by the electron multiplier section."

[0007] In the electromagnetic wave detection device described above, multiple holes in the insulating layer are formed on the metasurface at positions corresponding to each of the multiple antenna elements, and multiple electrode portions are formed on the insulating layer at positions corresponding to each of the multiple holes. In this case, electrons emitted from the metasurface and passing through the holes can be guided to the electron multiplication portion by the electrode portion. Therefore, electrons emitted from the metasurface can easily reach the electron multiplication portion, and the detection accuracy of electromagnetic waves can be improved.

[0008] In one embodiment of the present disclosure, the electromagnetic wave detection device may also be [2] "the electromagnetic wave detection device according to [1] above, wherein the insulating layer includes a first insulating layer and a second insulating layer located on the first insulating layer, and the plurality of electrode portions include a plurality of first electrode portions arranged between the first insulating layer and the second insulating layer at positions corresponding to each of the plurality of holes, and a plurality of second electrode portions arranged on the second insulating layer at positions corresponding to each of the plurality of holes." In this case, electrons can be more reliably guided to the electron multiplier portion by the first electrode portion and the second electrode portion.

[0009] In one embodiment of the electromagnetic wave detection device of the present disclosure, [3] "the electromagnetic wave detection device according to [2] above, wherein the insulating layer further includes a third insulating layer located on the second insulating layer, the plurality of second electrode portions are disposed between the second insulating layer and the third insulating layer, and the plurality of electrode portions further include a plurality of third electrode portions disposed on the third insulating layer at positions corresponding to each of the plurality of holes." In this case, electrons can be more reliably guided to the electron multiplier by the first electrode portion, the second electrode portion, and the third electrode portion.

[0010] In one embodiment of the electromagnetic wave detection device of the present disclosure, [4] "Each of the plurality of electrode portions surrounds a corresponding hole among the plurality of holes, and in the hole, the maximum width of the portion surrounded by the third electrode portion is greater than the maximum width of the portion surrounded by the first and second electrode portions, as described in [3] above." With this configuration, contact between the third electrode portion and the second electrode portion is suppressed, and manufacturing throughput can be improved.

[0011] In one embodiment of the electromagnetic wave detection device of the present disclosure, [5] "the electromagnetic wave detection device according to any one of [1] to [4] above, wherein each of the plurality of electrode portions includes an annular portion surrounding the hole." In this case, electrons can be more reliably guided to the electron multiplier portion by the plurality of electrode portions.

[0012] In one embodiment of the electromagnetic wave detection device of the present disclosure, [6] "the electromagnetic wave detection device according to [5] above, wherein the annular portion is formed in a completely closed ring." In this case, the annular portion can generate a more uniform electric field. Therefore, electrons can be more reliably induced to the electron multiplier.

[0013] In one embodiment of the electromagnetic wave detection device of the present disclosure, [7] "the annular portion is formed in a circular shape when viewed from a direction perpendicular to the metasurface, as described in [6] above." In this case, the annular portion can generate a more uniform electric field. Therefore, electrons can be more reliably induced to the electron multiplier.

[0014] According to one aspect of this disclosure, an electromagnetic wave detection device is provided that can improve the detection accuracy of electromagnetic waves.

[0015] Figure 1 is a schematic diagram of the electromagnetic wave detection device according to this embodiment. Figure 2 is a plan view of the electron emission section. Figure 3 is a partially enlarged view of the electron emission section including a plurality of antenna elements. Figure 4 is a partial perspective view showing the position of the electrode section relative to one antenna element. Figure 5 is a plan view showing the arrangement of the plurality of antenna elements and the plurality of electrode sections. Figure 6 is a partially plan view of the light receiving section corresponding to one antenna element. Figure 7 is a partially cross-sectional view of the electron emission section. Figures 8(a) to 8(c) are plan views showing modified examples of the plurality of electrode sections. Figures 9(a) to 9(c) are plan views showing yet another modified example of the plurality of electrode sections. Figures 10(a) to 10(c) are plan views showing yet another modified example of the plurality of electrode sections. Figure 11 is a plan view showing the arrangement of the plurality of antenna elements and the plurality of electrode sections in a modified example of this embodiment. Figure 12 is a plan view showing the arrangement of the plurality of antenna elements and the plurality of electrode sections in yet another modified example of this embodiment. Figure 13 is a plan view showing the arrangement of the plurality of antenna elements and the plurality of electrode sections in yet another modified example of this embodiment. Figure 14 is a partial cross-sectional view of the electron emission section in another modified example of this embodiment. Figure 15 is a schematic diagram illustrating multiple electrode sections. Figure 16 is a diagram illustrating field emission. Figure 17 is a graph illustrating field emission. Figure 18 is a diagram illustrating a comparative example. Figure 19(a) shows a metasurface as an example, Figure 19(b) shows an electrode section as an example, and Figure 19(c) shows an electrode section as another example. Figure 20 is a graph showing the performance of the electron emission section. Figure 21 is a cross-sectional view of an electron emission section as a comparative example.

[0016] Embodiments of this disclosure will be described in detail below with reference to the attached drawings. In this description, the same reference numerals will be used for elements that are the same or have the same function, and redundant explanations will be omitted. In each figure, the X, Y, and Z axes are orthogonal to each other.

[0017] First, the configuration of the electromagnetic wave detection device according to this embodiment will be described with reference to Figure 1. Figure 1 is a schematic diagram of the electromagnetic wave detection device according to this embodiment.

[0018] The electromagnetic wave detection device 1 detects incident electromagnetic waves L. The electromagnetic wave detection device 1 outputs an electrical signal in response to the incidence of electromagnetic waves L. The electromagnetic wave detection device 1 emits electrons P internally when electromagnetic waves L are incident, and multiplies the electrons in response to the emitted electrons. The electromagnetic wave detection device 1 detects electromagnetic waves L having a frequency band ranging from so-called millimeter waves to infrared light. The electromagnetic wave detection device 1 comprises, for example, a housing 10, an electron emission unit 20, an electron multiplication unit 40, and an electron collection unit 50. The electron collection unit 50 corresponds to the detection unit.

[0019] The housing 10 includes a valve 11 and a stem 12. The inside of the housing 10 is hermetically sealed by the valve 11 and the stem 12. In the example shown as an embodiment, the inside of the housing 10 is kept under vacuum. Vacuum includes not only absolute vacuum but also a state filled with gas at a pressure lower than atmospheric pressure. That is, the inside of the housing 10 is either under vacuum or filled with gas. For example, the inside of the housing 10 is 1 × 10⁻¹⁰ －４ Pa or more 1×10 －７ It is kept below Pa.

[0020] The valve 11 has an electromagnetic wave-transmitting window 11a. In this specification, "electromagnetic wave-transmitting" means the property of transmitting at least a portion of the frequency band of the incident electromagnetic wave L. In this embodiment, the housing 10 has a cylindrical shape. The stem 12 constitutes the bottom surface of the housing 10. The valve 11 constitutes the side surface of the housing 10 and the bottom surface facing the stem 12.

[0021] The window 11a forms the bottom surface facing the stem 12. The window 11a is, for example, circular in shape in plan view. The frequency characteristics of the transmittance of electromagnetic waves L differ depending on the material. For this reason, the window 11a is made of an optimal material according to the frequency band of the electromagnetic waves L incident on the electromagnetic wave detection device 1. For example, the window 11a includes at least one selected from, for example, quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide, calcium carbonate, and chalcogenide glass. By constructing the window 11a with a material selected from these, electromagnetic waves of any frequency band from millimeter waves to infrared light can be guided into the interior of the housing 10. For example, quartz is suitable as a material for electromagnetic wave-transmitting components with frequency bands of 0.1 THz to 5 THz, silicon is suitable for 0.04 THz to 11 THz and 46 THz or higher, magnesium fluoride is suitable for 40 THz or higher, germanium is suitable for 13 THz or higher, and zinc selenide is suitable for 14 THz or higher.

[0022] The electromagnetic wave detection device 1 further has a plurality of wires 13 that enable electrical connections between the outside and inside of the housing 10. The plurality of wires 13 are, for example, lead wires or pins. In this embodiment, the plurality of wires 13 are pins that pass through the stem 12 and extend from the inside to the outside of the housing 10. At least one of the plurality of wires 13 is connected to various members provided inside the housing 10.

[0023] The electron emission unit 20 is located inside the housing 10 and emits electrons P inside the housing 10 in response to the incidence of electromagnetic waves L. The electron emission unit 20 has two opposing main surfaces 20a and 20b. As shown in Figure 2, the electron emission unit 20 includes a substrate 21. Figure 2 is a plan view of the electron emission unit 20. The substrate 21 has two opposing main surfaces 21a and 21b. In the example shown as this embodiment, the substrate 21 is plate-shaped. The main surfaces 20a and 20b of the substrate 21 are, for example, rectangular in shape.

[0024] The main surfaces 20a and 20b are arranged parallel to the window 11a. The main surface 20a faces the window 11a. The main surface 20a corresponds to the incident surface to which electromagnetic waves L that have passed through the window 11a are incident. The substrate 21 is electromagnetic wave transparent to electromagnetic waves L that pass through the window 11a. Therefore, the substrate 21 transmits at least a portion of the frequency band of electromagnetic waves L that have passed through the window 11a. The material of the substrate 21 includes, for example, quartz. The material of the substrate 21 may also include, for example, silicon. The substrate 21 is rectangular in plan view. The substrate 21 is spaced apart from the window 11a and the electron multiplier section 40.

[0025] The substrate 21 includes a light-receiving unit 25. The light-receiving unit 25 emits electrons P in response to the incidence of electromagnetic waves L. In the example shown as this embodiment, the light-receiving unit 25 is rectangular in plan view and is provided on the main surface 21b. The light-receiving unit 25 may also be provided on the main surface 20a.

[0026] The electron multiplication unit 40 is located inside the housing 10 and has an incident surface 40a into which electrons P emitted from the electron emission unit 20 are incident. The electron multiplication unit 40 multiplies the electrons P incident on the incident surface 40a. In the example shown as this embodiment, the main surface 20b of the electron emission unit 20 faces the incident surface 40a of the electron multiplication unit 40. The light receiving unit 25 faces the incident surface 40a of the electron multiplication unit 40, and electrons P emitted from the light receiving unit 25 are incident on the incident surface 40a. The main surface 20a of the electron emission unit 20 faces the window 11a of the housing 10. Different potentials are applied to the electron emission unit 20 and the electron multiplication unit 40, respectively, so that a potential difference is created between them. For example, the electromagnetic wave detection device 1 is configured so that different potentials are applied to the metasurface S and the incident surface 40a, respectively.

[0027] In this specification, "A faces B" means that B is located in the direction normal to A than the plane tangent to A. In other words, "A faces B" means that when space is divided in two by a plane tangent to A, B is located on the side of A, not the other side of A. For example, in the electromagnetic wave detection device 1, as described above, the light receiving unit 25 faces the incident surface 40a of the electron multiplier unit 40. This means that the incident surface 40a of the electron multiplier unit 40 is located in the direction normal to the main surface 20b than the light receiving unit 25.

[0028] In the example shown as this embodiment, the electron multiplication unit 40 has a so-called line-focus type multi-stage dynode, as shown in Figure 1. The electron multiplication unit 40 has a focusing electrode 41 that focuses electrons and a multi-stage dynode 42 spaced apart from each other. The dynode 42 includes the incident surface 40a described above. In this embodiment, the electron multiplication unit 40 has 10 stages of dynode 42. A circular incident opening 41a is provided in the center of the focusing electrode 41. The multi-stage dynode 42 is arranged downstream of the incident opening 41a. One of the multiple wirings 13 is connected to each of the multi-stage dynode 42. A predetermined potential is applied to each of the multi-stage dynode 42 through the wiring 13. The multi-stage dynode 42 multiplies the electrons P that have passed through the incident opening 41a according to the applied potential. The focusing electrode 41 is electrically connected.

[0029] The electron collection unit 50 is located inside the housing 10 and collects electrons multiplied by the electron multiplication unit 40. In the example shown as this embodiment, the electron collection unit 50 includes an anode 51. The anode 51 is located closer to the stem 12 than the main surface 20b of the electron emission unit 20. One of a plurality of wires 13 is connected to the anode 51. A predetermined potential is applied to the anode 51 through the wire 13. The anode 51 captures electrons multiplied by a plurality of dynodes 42. The electron collection unit 50 may have a diode instead of the anode 51.

[0030] Next, the configuration of the electron emission unit 20 will be described in detail with reference to Figures 2 to 7. Figure 3 is a partially enlarged view of the electron emission unit.

[0031] As shown in Figure 2, the electron emission unit 20 includes a pair of electrode units 27 and 29 electrically connected to the light receiving unit 25, in addition to the light receiving unit 25. The pair of electrode units 27 and 29 apply a voltage to the light receiving unit 25. The electrode units 27 and 29 are spaced apart from each other. The pair of electrode units 27 and 29 are arranged to face each other on the main surface 21b.

[0032] The light-receiving unit 25 is located in the center of the main surface 21b. In the example shown as this embodiment, the light-receiving unit 25 is located on the main surface 21b between the electrode unit 27 and the electrode unit 29. The electrode unit 27, the light-receiving unit 25, and the electrode unit 29 are arranged in a predetermined direction in sequence. When the electromagnetic wave detection device 1 is in operation, different potentials are applied to the electrode unit 27 and the electrode unit 29. One of the electrode unit 27 and the electrode unit 29 may be configured to be connected to ground.

[0033] The light-receiving unit 25 includes a metasurface S. The metasurface S emits electrons P in response to the incidence of electromagnetic waves L. The metasurface S is of the active type. By applying different potentials to electrode units 27 and 29, electron emission when electromagnetic waves L are incident on the metasurface S is controlled. The metasurface S is contained in a patterned oxide layer or a patterned metal layer on the substrate 21. The material of the oxide layer is, for example, silicon dioxide and titanium oxide. The material of the metal layer is, for example, gold. In the example shown as this embodiment, an oxide layer is formed on the main surface 21b of a substrate 21 made of quartz, and a metal layer is formed on top of the oxide layer.

[0034] In this embodiment, the metasurface S is a transmissive metasurface. When an electromagnetic wave L is incident on a transmissive metasurface, electrons P are emitted from the side opposite to the surface on which the electromagnetic wave L was incident. In the electromagnetic wave detection device 1, the electromagnetic wave L that has passed through the window 11a is incident on the main surface 20a of the substrate 21. The electromagnetic wave L that has passed through the substrate 21 is incident on the metasurface S provided on the main surface 21b. The metasurface S emits electrons P in response to the electromagnetic wave L that has been incident on it by passing through the window 11a and the substrate 21.

[0035] The metasurface S includes a plurality of antenna elements 61. For example, in the metasurface S, the plurality of antenna elements 61 are arranged in a matrix in a two-dimensional arrangement on the main surface 21b. The plurality of antenna elements 61 are arranged in the X-axis direction and the Y-axis direction. The plurality of antenna elements 61 emit electrons P in response to the incidence of electromagnetic waves L. Each antenna element 61 includes a pair of conductive parts 62 and 63 that face each other. The conductive parts 62 and 63 are spaced apart from each other. The conductive part 62 is electrically connected to the electrode part 27. The conductive part 63 is electrically connected to the electrode part 29.

[0036] In the example shown in this embodiment, the antenna element 61 has, for example, a bowtie antenna shape. The conductive portion 62 and the conductive portion 63 each have a triangular shape when viewed from the Z-axis direction. The conductive portions 62 and 63 are each configured with the vertices of the triangle as their tips. The tips of the conductive portion 62 and the conductive portion 63 are spaced apart from each other and face each other in the X-axis direction. In other words, a gap is formed between the conductive portion 62 and the conductive portion 63 in one antenna element 61. In this case, the polarization direction of the electromagnetic wave L incident on the metasurface S is set in the X-axis direction.

[0037] The metasurface S further includes a pair of conductive wires 64 and 65. Conductive wire 64 is connected to a conductive portion 62. Conductive wire 65 is connected to a conductive portion 63. In the example shown as this embodiment, a plurality of conductive portions 62 arranged in the Y-axis direction are connected to a single conductive wire 64. A plurality of conductive portions 63 arranged in the Y-axis direction are connected to a single conductive wire 65.

[0038] The light receiving unit 25 further includes a lens layer LN. FIGS. 4 to 7 show the relationship between the metasurface S and the lens layer LN. The lens layer LN guides electrons emitted from the antenna element 61 in response to incidence of the electromagnetic wave L toward the incident surface 40a of the electron multiplying unit 40. The lens layer LN includes at least one electrode portion 70 and at least one insulating layer 81, 82, 83. In the example shown as the present embodiment, the lens layer LN includes a plurality of electrode portions 70 and a plurality of insulating layers 81, 82, 83. FIG. 4 is a partial perspective view showing the position of the electrode portion with respect to one antenna element. FIG. 5 is a plan view showing the arrangement of a plurality of antenna elements and a plurality of electrode portions. FIG. 6 is a partial plan view of the light receiving unit corresponding to one antenna element. FIG. 7 is a partial cross-sectional view of the electron emission portion. For example, the insulating layer 81 corresponds to a first insulating layer, the insulating layer 82 corresponds to a second insulating layer, and the insulating layer 83 corresponds to a third insulating layer.

[0039] The material of the electrode portion 70 includes, for example, a metal or a doped semiconductor. As the metal, the material of the electrode portion 70 includes at least one selected from, for example, Au, Ag, Pt, Cu, W, and Al. As the doped semiconductor, the material of the electrode portion 70 includes at least one selected from, for example, Si, GaAs, InGaAs, and InP. The material of the plurality of insulating layers 81, 82, 33 is, for example, SiO ２ , Al ２ O ３ , TiO ２ , SiN ｘ , SiC, and diamond, at least one selected therefrom.

[0040] As shown in FIG. 4, the lens layer LN includes, for example, a lens layer LN1, a lens layer LN2, and a lens layer LN3. The plurality of electrode portions 70 include, for example, an electrode portion 71, an electrode portion 72, and an electrode portion 73. The lens layer LN1 is constituted by the insulating layer 81 and the electrode portion 71. The lens layer LN2 is constituted by the insulating layer 82 and the electrode portion 72. The lens layer LN3 is constituted by the insulating layer 83 and the electrode portion 73.

[0041] The insulating layers 81, 82, and 83 are arranged on the metasurface S. The insulating layers 81, 82, and 83 include a plurality of holes HL through which electrons emitted from the antenna elements 61 pass. The plurality of holes HL respectively correspond to different antenna elements 61. The antenna elements 61 and the holes HL correspond in a one-to-one relationship. The plurality of holes HL are two-dimensionally arranged in a matrix in the X-axis direction and the Y-axis direction. The electron multiplying unit 40 multiplies electrons according to the electrons that have passed through the plurality of holes HL.

[0042] The insulating layers 81, 82, and 83 have holes HL at positions corresponding to each of the plurality of antenna elements 61. For example, in the insulating layers 81, 82, and 83, the holes HL are formed at positions overlapping the gaps of the antenna elements 61 when viewed from the Z-axis direction. In the example shown as the present embodiment, the tip of the conductive portion 62 and the tip of the conductive portion 63 are exposed in the holes HL when viewed from the Z-axis direction.

[0043] In the example shown as the present embodiment, a plurality of insulating layers 81, 82, and 83 are stacked on the metasurface S. For example, the insulating layer 82 is located on the insulating layer 81, and the insulating layer 83 is located on the insulating layer 82. The holes HL penetrate all of the plurality of insulating layers 81, 82, and 83.

[0044] The electrode portions 70 are arranged on the insulating layers 81, 82, and 83 at positions corresponding to each of the plurality of holes HL. In the example shown as the present embodiment, the plurality of electrode portions 70 include an electrode portion 71, an electrode portion 72, and an electrode portion 73 corresponding to the same hole HL. The electrode portion 71 is arranged on the insulating layer 81. The plurality of electrode portions 71 are arranged at positions corresponding to each of the plurality of holes HL between the insulating layer 81 and the insulating layer 82. The electrode portion 72 is arranged on the insulating layer 82. The plurality of electrode portions 72 are arranged at positions corresponding to each of the plurality of holes HL between the insulating layer 82 and the insulating layer 83. The electrode portion 73 is arranged on the insulating layer 83. For example, the electrode portion 71 corresponds to a first electrode portion, the electrode portion 72 corresponds to a second electrode portion, and the electrode portion 73 corresponds to a third electrode portion.

[0045] Each of the multiple electrode portions 70 surrounds a corresponding hole HL among the multiple holes HL. In the example shown as this embodiment, the multiple electrode portions 70 include an annular portion 70a that is formed in an annular shape. The annular portion 70a surrounds a hole HL. The multiple electrode portions 70 include electrode portions 71, 72, and 73 that surround the same hole HL. Each of the multiple electrode portions 71, 72, and 73 is formed in an annular shape that surrounds a hole HL.

[0046] Each of the multiple electrode portions 71 includes an annular portion 71a and a linear portion 71b. Each of the multiple electrode portions 72 includes an annular portion 72a and a linear portion 72b. Each of the multiple electrode portions 73 includes an annular portion 73a and a linear portion 73b. The annular portion 70a includes an annular portion 71a, an annular portion 72a, and an annular portion 73a.

[0047] Viewed from the Z-axis direction, the centers of the annular portions 71a, 72a, and 73a are located at hole HL. Hole HL penetrates the inner regions of each of the annular portions 71a, 72a, and 73a. Viewed from the Z-axis direction, the gap of the antenna element 61 overlaps with the inner regions of each of the annular portions 71a, 72a, and 73a. Viewed from the Z-axis direction, the tips of the conductive portion 62 and the conductive portion 63 are located in the inner regions of each of the annular portions 71a, 72a, and 73a. For example, the maximum width of the annular portion 73a is greater than the maximum widths of the annular portions 71a and 72a.

[0048] Multiple annular portions 71a are arranged in a matrix-like manner in two dimensions on the insulating layer 81 in the X-axis direction and the Y-axis direction. Multiple annular portions 72a are arranged in a matrix-like manner in two dimensions on the insulating layer 82 in the X-axis direction and the Y-axis direction. Multiple annular portions 73a are arranged in a matrix-like manner in two dimensions on the insulating layer 83 in the X-axis direction and the Y-axis direction.

[0049] In this specification, “annular” includes both open shapes and completely closed shapes. An open shape corresponds, for example, to a shape with a break. A completely closed shape corresponds, for example, to a continuous shape without a break. In the example shown as this embodiment, each of the plurality of annular portions 71a, 72a, 73a is formed as a completely closed annular shape.

[0050] In this specification, "annular" includes shapes with a circular inner circumference in plan view and shapes with a polygonal inner circumference in plan view. In the example shown as this embodiment, each of the multiple annular portions 71a, 72a, 73a is formed in an annular shape when viewed from a direction perpendicular to the metasurface S, as shown in Figures 4, 5, and 6. The shape of each of the multiple annular portions 71a, 72a, 73a and the cross-sectional shape of the hole HL surrounded by the corresponding annular portions 71a, 72a, 73a are similar or completely different. In the example shown as this embodiment, the cross-sectional shape of the hole HL surrounded by the corresponding annular portions 71a, 72a, 73a are similar. "Similarity" also includes the range of manufacturing tolerances.

[0051] In the example shown as this embodiment, as shown in Figure 5, multiple annular portions 71a corresponding to different antenna elements 61 are electrically connected by a linear portion 71b. For example, multiple annular portions 71a arranged in the Y-axis direction are electrically connected by a single linear portion 71b. Multiple annular portions 72a corresponding to different antenna elements 61 are electrically connected by a linear portion 72b. For example, multiple annular portions 72a arranged in the Y-axis direction are electrically connected by a single linear portion 72b. Multiple annular portions 73a corresponding to different antenna elements 61 are electrically connected by a linear portion 73b. For example, multiple annular portions 73a arranged in the Y-axis direction are electrically connected by a single linear portion 73b.

[0052] The annular portions 71a, 72a, and 73a corresponding to the same antenna element 61 overlap when viewed from the Z-axis direction. The linear portions 71b, 72b, and 73b corresponding to the same antenna element 61 do not overlap when viewed from the Z-axis direction. When projected in the Z-axis direction, the linear portions 71b, 72b, and 73b corresponding to the same antenna element 61 are spaced apart from each other.

[0053] In the same hole HL, the maximum width R1 of the portion surrounded by electrode portion 73 is greater than the maximum width R2 of the portion surrounded by electrode portion 71 and electrode portion 72. In hole HL, the portion surrounded by electrode portion 73 is defined by electrode portion 73. In hole HL, the portion surrounded by electrode portion 71 and electrode portion 72 is defined by insulating layers 81, 82, and 83. In the light-receiving portion 25, the portion surrounded by electrode portion 73 in hole HL corresponds to the portion defined by electrode portion 73. In the light-receiving portion 25, the portion surrounded by electrode portion 71 and electrode portion 72 in hole HL corresponds to the portion defined by insulating layers 81, 82, and 83.

[0054] The maximum width R1 of the portion surrounded by electrode portion 73, and the maximum width R2 of the portion surrounded by electrode portion 71 and electrode portion 72, are greater than the gap R3 of the corresponding antenna element 61 among the multiple antenna elements 61. The gap R3 corresponds, for example, to the shortest distance between conductive portion 62 and conductive portion 63. The gap R3 is, for example, 0.1 μm or more and 10 μm or less.

[0055] As shown in Figure 7, the electron emission unit 20 further includes a plurality of electrodes 67 that apply a potential to a plurality of antenna elements 61. The plurality of electrodes 67 are electrically connected to the plurality of antenna elements 61 through conductive wires 64 and 65.

[0056] The electron emission unit 20 further includes an electrode 76 that applies a potential to a plurality of electrode portions 71, an electrode 77 that applies a potential to a plurality of electrode portions 72, and an electrode 78 that applies a potential to a plurality of electrode portions 73. Electrode 76 is electrically connected to a plurality of annular portions 71a through a linear portion 71b. Electrode 77 is electrically connected to a plurality of annular portions 72a through a linear portion 72b. Electrode 78 is electrically connected to a plurality of annular portions 73a through a linear portion 73b.

[0057] Multiple antenna elements 61 are provided on the main surface 21b of the substrate 21. Multiple conductive parts 62, 63 are provided on the main surface 21b. Multiple electrodes 67 are provided on the main surface 21b. An insulating layer 81 is provided on the main surface 21b and the multiple antenna elements 61. Multiple annular parts 71a and electrodes 76 are provided on the insulating layer 81. An insulating layer 82 is provided on the insulating layer 81 and the multiple electrode parts 71. Multiple annular parts 72a and electrodes 77 are provided on the insulating layer 82. An insulating layer 83 is provided on the insulating layer 82 and the multiple electrode parts 72. Multiple annular parts 73a and electrodes 78 are provided on the insulating layer 83.

[0058] The above-described configuration on the substrate 21 is formed, for example, by vapor deposition and etching. The multiple antenna elements 61, multiple conductive wires 64, 65, multiple electrodes 67, multiple electrode portions 71, 72, 73, and multiple electrodes 76, 77, 78 are formed of a metal such as gold. The insulating layers 81, 82, 83 are formed of an oxide or nitride, for example.

[0059] Next, the configuration of a modified electromagnetic wave detection device will be explained using Figures 8(a) to 10(c). This modified configuration differs from the example described above in terms of the configuration of the electrode section 70. The following explanation will mainly focus on the differences from the example described above. Figures 8(a) to 10(c) show another modified configuration of multiple electrode sections.

[0060] As a modification of this embodiment, the lens layer LN may include lens layers LN11, LN12, and LN13 instead of lens layers LN1, LN2, and LN3, as shown in Figures 8(a) to 8(c). Lens layer LN11 is composed of an insulating layer 81 and an electrode portion 111. Lens layer LN12 is composed of an insulating layer 82 and an electrode portion 112. Lens layer LN13 is composed of an insulating layer 83 and an electrode portion 113. Electrode portions 111, 112, and 113 differ from electrode portions 71, 72, and 73 in that they include annular portions 111a, 112a, and 113a instead of annular portions 71a, 72a, and 73a.

[0061] Each of the multiple electrode portions 111, 112, and 113 is formed in an annular shape surrounding the hole HL. Viewed from the Z-axis direction, the centers of the annular portions 111a, 112a, and 113a are located in the hole HL. The hole HL penetrates the inner regions of each of the annular portions 111a, 112a, and 113a. In this modified example, each of the multiple annular portions 111a, 112a, and 113a is formed in a pentagonal annular shape when viewed from a direction perpendicular to the metasurface S, as shown in Figure 11.

[0062] As a modification of this embodiment, the lens layer LN may include lens layers LN21, LN22, and LN23 instead of lens layers LN1, LN2, and LN3, as shown in Figures 9(a) to 9(c). Lens layer LN21 is composed of an insulating layer 81 and an electrode portion 121. Lens layer LN22 is composed of an insulating layer 82 and an electrode portion 122. Lens layer LN23 is composed of an insulating layer 83 and an electrode portion 123. Electrode portions 121, 122, and 123 differ from electrode portions 71, 72, and 73 in that they include annular portions 121a, 122a, and 123a instead of annular portions 71a, 72a, and 73a.

[0063] Each of the multiple electrode portions 121, 122, and 123 is formed in an annular shape surrounding the hole HL. Viewed from the Z-axis direction, the centers of the annular portions 121a, 122a, and 123a are located in the hole HL. The hole HL penetrates the inner regions of each of the annular portions 121a, 122a, and 123a. In this modified example, each of the multiple annular portions 121a, 122a, and 123a is formed in a rectangular annular shape when viewed from a direction perpendicular to the metasurface S, as shown in Figures 9(a) to 9(c).

[0064] As a modification of this embodiment, the lens layer LN may include lens layers LN31, LN32, and LN33 instead of lens layers LN1, LN2, and LN3, as shown in Figures 10(a) to 10(c). Lens layer LN31 is composed of an insulating layer 81 and an electrode portion 131. Lens layer LN32 is composed of an insulating layer 82 and an electrode portion 132. Lens layer LN33 is composed of an insulating layer 83 and an electrode portion 133. Electrode portions 131, 132, and 133 differ from electrode portions 71, 72, and 73 in that they include annular portions 131a, 132a, and 133a instead of annular portions 71a, 72a, and 73a.

[0065] Each of the multiple electrode portions 131, 132, and 133 is formed in an annular shape surrounding the hole HL. Viewed from the Z-axis direction, the centers of the annular portions 131a, 132a, and 133a are located in the hole HL. The hole HL penetrates the inner regions of each of the annular portions 131a, 132a, and 133a. In this modified example, each of the multiple annular portions 131a, 132a, and 133a is formed in an octagonal annular shape when viewed from a direction perpendicular to the metasurface S, as shown in Figures 10(a) to 10(c).

[0066] Next, the configuration of a modified electromagnetic wave detection device will be explained using Figure 11. This modified configuration differs from the example described above in terms of the antenna element configuration. The differences from the example described above will be explained below. Figure 11 shows the arrangement of multiple antenna elements and multiple electrode sections.

[0067] This modified electromagnetic wave detection device includes a light-receiving unit 25A instead of the light-receiving unit 25. The metasurface S of the light-receiving unit 25A is of the active type. By applying different potentials to the electrode units 27 and 29, electron emission when electromagnetic waves L are incident on the metasurface S is controlled. The metasurface S of the light-receiving unit 25A includes multiple antenna elements 141 instead of multiple antenna elements 61. Each antenna element 141 has a dipole antenna shape.

[0068] On the metasurface S of the light-receiving unit 25A, a plurality of antenna elements 141 are arranged in a matrix in a two-dimensional manner on the main surface 21b. The plurality of antenna elements 141 are arranged in the X-axis direction and the Y-axis direction. The plurality of antenna elements 141 emit electrons P in response to the incidence of electromagnetic waves L. Each antenna element 141 includes a pair of conductive parts 142 and 143 that face each other. The conductive parts 142 and 143 are spaced apart from each other. Conductive part 142 is electrically connected to electrode part 27. Conductive part 143 is electrically connected to electrode part 29.

[0069] In this modified example, the conductive portion 142 and the conductive portion 143 each exhibit a linear shape when viewed from the Z-axis direction. The tip of the conductive portion 142 and the tip of the conductive portion 143 are spaced apart from each other and face each other in the X-axis direction. In other words, a gap is formed between the conductive portion 142 and the conductive portion 143 in one antenna element 141. When viewed from the Z-axis direction, the gap in the antenna element 141 overlaps with the inner region of the annular portion 70a. When viewed from the Z-axis direction, the tip of the conductive portion 142 and the tip of the conductive portion 143 are located in the inner region of the annular portion 70a. In this case, the polarization direction of the electromagnetic wave L incident on the metasurface S is set in the X-axis direction.

[0070] Next, the configuration of a modified electromagnetic wave detection device will be explained using Figure 12. This modified configuration differs from the example described above in terms of the antenna element configuration. The following will mainly explain the differences from the example described above. Figure 12 shows the arrangement of multiple antenna elements and multiple electrode sections.

[0071] This modified electromagnetic wave detection device includes a light-receiving unit 25B instead of a light-receiving unit 25. The metasurface S of the light-receiving unit 25B is of the passive type. No external potential is applied to the metasurface S of the light-receiving unit 25B. The metasurface S of the light-receiving unit 25B includes multiple antenna elements 151 instead of multiple antenna elements 61. Each antenna element 151 has a split-ring shape.

[0072] On the metasurface S of the light-receiving unit 25B, a plurality of antenna elements 151 are arranged in a matrix in a two-dimensional manner on the main surface 21b. The plurality of antenna elements 151 are arranged in the X-axis direction and the Y-axis direction. The plurality of antenna elements 151 emit electrons in response to the incidence of electromagnetic waves.

[0073] Each antenna element 151 has a C-shape when viewed from the Z-axis direction. Each antenna element 151 includes a pair of conductive parts 152 and 153 that face each other. Conductive parts 152 and 153 are electrically connected. In this modified example, conductive parts 152 and 153 each have a linear shape when viewed from the Z-axis direction. The tip of conductive part 152 and the tip of conductive part 153 are spaced apart from each other and face each other in the X-axis direction. In other words, a gap is formed between conductive parts 152 and 153 in one antenna element 151. When viewed from the Z-axis direction, the gap of the antenna element 151 overlaps with the inner region of the annular part 70a. When viewed from the Z-axis direction, the tip of conductive part 152 and the tip of conductive part 153 are located in the inner region of the annular part 70a. In this case, the polarization direction of the electromagnetic wave L incident on the metasurface S is set in the X-axis direction.

[0074] Next, the configuration of a modified electromagnetic wave detection device will be explained using Figure 13. This modified configuration differs from the example described above in terms of the antenna element configuration. The differences from the example described above will be explained below. Figure 13 shows the arrangement of multiple antenna elements and multiple electrode sections.

[0075] This modified electromagnetic wave detection device includes a light-receiving unit 25C instead of a light-receiving unit 25. The metasurface S of the light-receiving unit 25C is of the passive type. No external potential is applied to the metasurface S of the light-receiving unit 25C. The metasurface S of the light-receiving unit 25C includes multiple antenna elements 161 instead of multiple antenna elements 61. Each antenna element 161 has a double split-ring shape.

[0076] On the metasurface S of the light-receiving section 25C, a plurality of antenna elements 161 are arranged in a matrix in a two-dimensional manner on the main surface 21b. The plurality of antenna elements 161 are arranged in the X-axis direction and the Y-axis direction. The plurality of antenna elements 161 emit electrons in response to the incidence of electromagnetic waves.

[0077] Each antenna element 161 has a shape formed by combining two C-shapes when viewed from the Z-axis direction. Each antenna element 161 includes a pair of conductive parts 162 and 163 that face each other. Conductive parts 162 and 163 are electrically connected. In this modified example, conductive parts 162 and 163 each have a linear shape when viewed from the Z-axis direction. The tips of conductive parts 162 and 163 are spaced apart from each other and face each other in the X-axis direction. In other words, a gap is formed between conductive parts 162 and 163 in one antenna element 161. When viewed from the Z-axis direction, the gap in the antenna element 161 overlaps with the inner region of the annular part 70a. When viewed from the Z-axis direction, the tips of conductive parts 162 and 163 are located in the inner region of the annular part 70a. In this case, the polarization direction of the electromagnetic wave L incident on the metasurface S is set in the X-axis direction.

[0078] Next, the configuration of a modified electromagnetic wave detection device will be explained using Figure 14. This modified configuration differs from the example described above in terms of the configuration of the electron emission section. The differences from the example described above will be explained below. The electron emission section 20D differs from the electron emission section 20 in that it contains only one lens layer LN. Figure 14 is a partial cross-sectional view of the electron emission section. The electron emission section 20D includes a light receiving section 25D instead of a light receiving section 25.

[0079] The electron emission section 20D does not include lens layers LN2 and LN3, nor does it include electrodes 77 for applying potential to a plurality of electrode sections 72, nor electrodes 78 for applying potential to a plurality of electrode sections 73. In the electron emission section 20D, a plurality of antenna elements 61 are provided on the main surface 21b of the substrate 21. A plurality of conductive sections 62 and 63 are provided on the main surface 21b. A plurality of electrodes 67 are provided on the main surface 21b. An insulating layer 81 is provided on the main surface 21b and the plurality of antenna elements 61. A plurality of annular sections 71a and a plurality of electrodes 76 are provided on the insulating layer 81.

[0080] In the same hole HL of the electron emission section 20D, the maximum width R1 of the portion surrounded by the electrode section 71 is greater than the maximum width R2 of the portion defined by the insulating layer 81. The maximum width R1 of the portion surrounded by the electrode section 71 and the maximum width R2 of the portion defined by the insulating layer 81 are greater than the gap R3 of the corresponding antenna element 61 among the multiple antenna elements 61. The gap R3 corresponds, for example, to the shortest distance between conductive section 62 and conductive section 63. In the light receiving section 25D, the portion surrounded by the electrode section 71 in the hole HL corresponds to the portion defined by the electrode section 71.

[0081] Next, the operation of the electromagnetic wave detection device 1 in this embodiment will be described using Figures 15, 16, and 17. Potentials are applied to the metasurface S, electrode section 70, dynodes 42a, 42b, and anode 51, respectively, through the wiring 13. Potentials are applied to the metasurface S through the wiring 13 and electrode sections 27, 29. The potentials applied to each of the metasurface S, electrode section 70, dynodes 42a, 42b, and anode 51 are set to increase sequentially as they approach the anode 51 from the metasurface S. Different potentials are applied to the conductive section 62 and conductive section 63. One of the conductive section 62 and conductive section 63 may be connected to ground.

[0082] Electron emission includes thermionic emission achieved by heating electrodes, photoelectron emission achieved by applying photons, secondary emission achieved by colliding electrons traveling at the speed of light, and field electron emission achieved in the presence of an electrostatic field. In the metasurface S, field electron emission occurs when electromagnetic waves are incident on the antenna element 61.

[0083] As shown in Figure 15, the electromagnetic wave L passes through the window 11a of the housing 10, then through the substrate 21, and is incident on the metasurface S. When the electromagnetic wave L is incident on the antenna element 61, an electric field is induced around the antenna element 61. When the electromagnetic wave L is incident on the antenna element 61, an electric field is generated between the conductive parts 62 and 63, as shown in Figure 16. The electromagnetic wave L incident on the antenna element 61 is confined to a relatively small metallic region formed by the conductive parts 62 and 63, and the electric field is resonantly amplified. As a result, if the inside of the housing 10 is kept in a vacuum, band bending occurs, and the potential barrier at the antenna-vacuum interface becomes thinner. Similarly, if the inside of the housing 10 is filled with gas, the potential barrier at the antenna-gas interface becomes thinner. Electrons present in the antenna element 61 pass through the potential barrier by the tunneling effect. Electrons that have passed through the potential barrier are accelerated by the electric field around the antenna element 61. As a result, electrons on the surfaces of the conductive parts 62 and 63 are emitted to the outside by the tunnel effect. For example, Figure 17 shows the potential on a metal surface at a temperature of 300 K. For example, due to the incidence of electromagnetic waves, 10 electrons enter the gap in the antenna element 61. ９ An electric field of V / m is generated, causing electrons to be emitted from the metal.

[0084] The smaller the size of the antenna element 61, the more easily field electron emission occurs for electromagnetic waves with shorter wavelengths, i.e., electromagnetic waves with higher frequencies. In other words, the smaller the gap R3 of the antenna element 61, the more easily field electron emission occurs for electromagnetic waves with shorter wavelengths, i.e., electromagnetic waves with higher frequencies. The metasurface S can handle electromagnetic waves in the mid-infrared and higher wavelength bands, particularly electromagnetic waves in the frequency band of 100 GHz to 10 THz, which are considered terahertz waves, depending on changes in the structure of the antenna element 61, such as the gap R3. The metasurface S may be configured to handle electromagnetic waves in the mid-infrared and higher wavelength bands, particularly the frequency band of 100 GHz to 10 THz, which corresponds to the frequency band of terahertz waves, depending on changes in the structure of the antenna element 61, such as the gap R3.

[0085] Electrons emitted from the antenna element 61 pass through the hole HL. Potentials are applied to the annular portions 71a, 72a, and 73a surrounding the hole HL. For example, a potential E1 is applied to the annular portion 71a, a potential E2 to the annular portion 72a, and a potential E3 to the annular portion 73a. Electrons P emitted from the antenna element 61 are guided in direction α by the electric field generated by the annular portions 71a, 72a, and 73a, and reach the incident surface 40a of the electron multiplier 40. Electrons P emitted from the antenna element 61 are guided to the incident surface 40a of the electron multiplier 40 by the electric field generated by the annular portions 71a, 72a, and 73a. For example, potentials E1 and E3 are ground, and potential E2 has a different value from potentials E1 and E3. By controlling the value of potential E2, the trajectory of electrons emitted from the hole HL is controlled.

[0086] The electron multiplication unit 40 multiplies electrons in response to electrons passing through multiple holes HL. The electron multiplication unit 40 multiplies electrons in response to electrons incident on the incident surface 40a. Electrons emitted from the electron emission unit 20 are focused by the focusing electrode 41 and sent to the first-stage dynode 42. When electrons are incident on the first-stage dynode 42, secondary electrons are emitted from the first-stage dynode 42 toward the second-stage dynode 42. When electrons are incident on the second-stage dynode 42, secondary electrons are emitted toward the third-stage dynode 42. In this way, electrons are sequentially sent from the first-stage dynode 42 to the tenth-stage dynode 42 while being multiplied. Cascade multiplication is performed in the electron multiplication unit 40 on electrons emitted from the electron emission unit 20.

[0087] The electrons multiplied by the electron multiplier unit 40 are collected by the anode 51, which is the electron collection unit 50, and output as an output signal from the anode 51 through the wiring 13. In other words, the electron collection unit 50 detects the electrons multiplied by the electron multiplier unit 40.

[0088] Next, the effects of the electromagnetic wave detection device according to this embodiment will be explained. When electromagnetic waves L are incident on the metasurface S, electrons can be emitted from the metasurface S by field electron emission. However, as shown in Figure 18, if the electrode portion 70 is not formed, electrons P emitted from the metasurface S may move along the main surface 21b on which the metasurface S is provided without reaching the electron multiplication portion 40. Even if electric field enhancement occurs in the gap of the antenna element, the electric field that emits electrons in the direction along the main surface 21b may be more dominant than the direction normal to the main surface 21b. In this case, fewer electrons reach the electron multiplication portion 40, making it difficult to detect the electromagnetic waves L incident on the metasurface S.

[0089] In the electromagnetic wave detection device 1, multiple holes HL in the insulating layer 81 are formed on the metasurface S at positions corresponding to each of the multiple antenna elements 61, and multiple electrode portions 70 are formed on the insulating layer 81 at positions corresponding to each of the multiple holes HL. In this case, electrons emitted from the metasurface S and passing through the holes HL can be guided to the electron multiplier portion 40 by the electrode portion 70. Therefore, electrons emitted from the metasurface S can easily reach the electron multiplier portion 40, and the detection accuracy of electromagnetic waves can be improved.

[0090] Figures 19(a) to 19(c) show the components used to verify the effectiveness of the electromagnetic wave detection device according to this embodiment. Figure 19(a) shows a configuration similar to that of the antenna element 61 in the metasurface S described above. Figure 19(b) shows a planar electrode portion 201 used as a lens layer. The planar electrode portion 201 has a hole 202 in the center. Figure 19(c) shows an electrode portion 70 used as a lens layer. The annular portion 71a of the electrode portion 70 is composed of a radius Rs.

[0091] In this verification, the resonance characteristics of field electron emission were simulated for the following cases: when no configuration corresponding to a lens layer is used on the metasurface S; when a planar electrode portion 201 is provided on the metasurface S; and when an electrode portion 70 is provided on the metasurface S. For the case where an electrode portion 70 having an annular portion 71a is provided on the metasurface S, simulations were performed for multiple cases with different radii Rs. Figure 20 shows the verification results.

[0092] In Figure 20, data D1 shows the data when a planar electrode portion 201 is provided on the metasurface S. Data D2 shows the data when a configuration corresponding to a lens layer is not used on the metasurface S. Data D3 shows the data when an electrode portion 70 with a radius Rs of 1 μm is provided on the metasurface S. Data D4 shows the data when an electrode portion 70 with a radius Rs of 5 μm is provided on the metasurface S. Data D5 shows the data when an electrode portion 70 with a radius Rs of 10 μm is provided on the metasurface S. Data D6 shows the data when an electrode portion 70 with a radius Rs of 15 μm is provided on the metasurface S.

[0093] From the above verification results, it was confirmed that when the planar electrode portion 201 is provided to the metasurface S, the resonance characteristics are not maintained. On the other hand, when the electrode portion 70 having an annular portion 71a is provided to the metasurface S, it was confirmed that the resonance characteristics are maintained, similar to the case when a configuration equivalent to a lens layer is not used for the metasurface S. When the planar electrode portion 201 is provided, it is thought that capacitance is affecting the resonance characteristics. It is thought that the influence of capacitance on the resonance characteristics can be reduced with the electrode portion 70 having an annular portion 71a.

[0094] In the electromagnetic wave detection device 1, the multiple electrode portions 71 are positioned between the insulating layer 81 and the insulating layer 82 at positions corresponding to each of the multiple holes HL. The multiple electrode portions 72 are positioned on the insulating layer 82 at positions corresponding to each of the multiple holes HL. In this case, the multiple electrode portions 71 and 72 can control the electrons emitted from each of the multiple holes HL in both the direction normal to the metasurface S and the direction along the metasurface S. Therefore, the electrons emitted from each of the multiple holes HL can be more reliably guided to accumulate in the electron multiplier portion 40.

[0095] In the electromagnetic wave detection device 1, the plurality of electrode portions 72 are arranged between the insulating layer 82 and the insulating layer 83. The plurality of electrode portions 70 further includes a plurality of electrode portions 73 arranged on the insulating layer 83 at positions corresponding to each of the plurality of holes HL. In this case, the plurality of electrode portions 71, the plurality of electrode portions 72, and the plurality of electrode portions 73 can control the electrons emitted from each of the plurality of holes HL in both the direction normal to the metasurface S and the direction along the metasurface S, and the energy of the electrons can also be controlled. Therefore, electrons emitted from each of the plurality of holes HL can be more reliably guided to gather in the electron multiplier portion 40.

[0096] Figure 21 shows an electron emission unit 220 as a comparative example. The electron emission unit 220 includes a light receiving unit 225. In the light receiving unit 225, the maximum width R1 of the portion surrounded by the electrode portion 73 and the maximum width R2 of the portion surrounded by the electrode portions 71 and 72 are the same. In the light receiving unit 225, the annular portion 271a corresponding to the annular portion 71a is normally constructed. However, in the light receiving unit 225, a defect DE occurs in the annular portion, and the annular portion 272a corresponding to the annular portion 72a and the annular portion 273a corresponding to the annular portion 73a are short-circuited. This is because an undercut occurred in the insulating layer during etching when forming the hole HL, causing the annular portion 273a to droop toward the annular portion 272a.

[0097] In the electromagnetic wave detection device 1, the maximum width R1 of the portion surrounded by electrode portion 73 in hole HL is greater than the maximum width R2 of the portion surrounded by electrode portions 71 and 72. In this case, the occurrence of undercuts prevents the annular portion 273a from sagging toward the annular portion 272a. Therefore, contact between electrode portion 73 and electrode portion 72 is suppressed, making it difficult for defective products to occur. With an electromagnetic wave detection device 1 having such a configuration, manufacturing throughput can be improved.

[0098] Each of the multiple electrode portions 71 includes an annular portion 71a surrounding the hole HL. In this case, a uniform electric field is generated by the annular portion 71a, and electrons can be more reliably guided to the electron multiplier portion 40.

[0099] The annular portion 71a is formed as a completely closed ring. In this case, the annular portion 71a can generate a more uniform electric field. In addition, the resonance characteristics of the metasurface S are ensured. Therefore, electrons can be more reliably guided to the electron multiplier portion 40.

[0100] The annular portion 71a may be formed in a circular shape when viewed from a direction perpendicular to the metasurface S. In this case, the annular portion 71a can generate a more uniform electric field. Furthermore, the resonance characteristics of the metasurface S are ensured. Therefore, electrons can be more reliably guided to the electron multiplier portion 40.

[0101] While embodiments and modifications of this disclosure have been described above, this disclosure is not necessarily limited to the embodiments and modifications described above, and various modifications are possible without departing from its essence.

[0102] For example, the above examples showed a configuration with three lens layers LN and a configuration with one lens layer LN. However, the number of lens layers LN is not limited to these. For example, two or four or more lens layers LN may be provided.

[0103] For example, the electron emission unit 20 may include only electrode units 71 and 72 as the electrode unit 70, without including electrode unit 73. In this case, for example, the potential E2 applied to electrode unit 72 is ground, and the potential E1 applied to electrode unit 71 has a different value from potential E2. The orbit of electrons emitted from the pore HL is controlled by controlling the value of potential E1.

[0104] 1...Electromagnetic wave detection device, HL...Hole, 27, 29, 70, 71, 72, 73, 111, 112, 113, 121, 122, 123, 131, 132, 133...Electrode part, 40...Electron multiplication part, 61, 141, 151, 161...Antenna element, 70a, 71a, 72a, 73a, 111a, 112a, 113a, 121a, 122a, 123a, 131a, 132a, 133a, 271a, 272a, 273a...Annular part, 81, 82, 83...Insulating layer, L...Electromagnetic wave, P...Electron, R1, R2...Maximum width, S...Metasurface, α...Direction.

Claims

1. An electromagnetic wave detection device comprising: a metasurface containing a plurality of antenna elements that emit electrons in response to the incidence of electromagnetic waves; an insulating layer disposed on the metasurface and having a plurality of holes through which the electrons pass at positions corresponding to each of the plurality of antenna elements; a plurality of electrode portions disposed on the insulating layer at positions corresponding to each of the plurality of holes; an electron multiplier portion that multiplies electrons in response to the electrons that have passed through the plurality of holes; and a detection portion that detects electrons multiplied by the electron multiplier portion.

2. The electromagnetic wave detection device according to claim 1, wherein the insulating layer includes a first insulating layer and a second insulating layer located on the first insulating layer, and the plurality of electrode portions include a plurality of first electrode portions arranged between the first insulating layer and the second insulating layer at positions corresponding to each of the plurality of holes, and a plurality of second electrode portions arranged on the second insulating layer at positions corresponding to each of the plurality of holes.

3. The electromagnetic wave detection device according to claim 2, wherein the insulating layer further includes a third insulating layer located on the second insulating layer, the plurality of second electrode portions are disposed between the second insulating layer and the third insulating layer, and the plurality of electrode portions further include a plurality of third electrode portions disposed on the third insulating layer at positions corresponding to each of the plurality of holes.

4. The electromagnetic wave detection device according to claim 3, wherein each of the plurality of electrode portions surrounds a corresponding hole among the plurality of holes, and in the hole, the maximum width of the portion surrounded by the third electrode portion is greater than the maximum width of the portion surrounded by the first and second electrode portions.

5. The electromagnetic wave detection device according to claim 1, wherein each of the plurality of electrode portions includes an annular portion surrounding the hole.

6. The electromagnetic wave detection device according to claim 5, wherein the annular portion is formed in a completely closed annular shape.

7. The electromagnetic wave detection device according to claim 6, wherein the annular portion is formed in a circular shape when viewed from a direction perpendicular to the metasurface.

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