STRUCTURE, TERAHERTZ BAND ELECTROMAGNETIC WAVE EMISSION ELEMENT, AND TERAHERTZ BAND ELECTROMAGNETIC WAVE EMISSION DEVICE

Abstract

To provide a structural body, terahertz-band electromagnetic wave oscillation element, and terahertz-band electromagnetic wave oscillation device that enable high-intensity electromagnetic wave radiation.SOLUTION: Provided are a structural body, a terahertz-band electromagnetic wave oscillation element, and a terahertz-band electromagnetic wave oscillation device. The structural body includes a superconducting element and first and second support substrates. The superconducting element and the first and second support substrates are stacked so that they electrically conduct in the direction of the thickness of the superconducting element. The first and second support substrates are each provided with a reflective mechanism that reflects electromagnetic waves generated by the superconducting element. According to this, electromagnetic waves generated from the superconducting element are reflected between the first and second support substrates, thereby confining the electromagnetic waves between the two support substrates. Then, by feeding back the confined electromagnetic waves to the superconducting element, phase synchronization of the electromagnetic waves generated by the superconducting element is enhanced, enabling high-intensity electromagnetic wave radiation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a structure including a superconducting element, and more particularly to a terahertz band electromagnetic wave oscillation element and a terahertz band electromagnetic wave oscillation device that oscillate terahertz band electromagnetic waves. [Background technology]

[0002] In recent years, terahertz waves (0.1 THz to 10 THz), which have wavelengths intermediate between radio waves and light, have been attracting attention. Terahertz waves travel in a straight line like light, and like radio waves, they can penetrate materials such as paper and plastic. Furthermore, the frequency of the terahertz band is equal to the frequencies of molecular rotation and vibration, crystal lattice vibration, and protein and other polymer vibration. Therefore, terahertz waves are not only useful for identifying various materials, but are also expected to be used in a wide range of industrial fields, including non-destructive testing such as imaging, security, high-speed communications, astronomy, and medicine, and are attracting attention.

[0003] In recent years, an oscillator using a single crystal of a high-temperature superconductor has been proposed as one of the small elements that generate terahertz waves. For example, Patent Documents 1 and 2 propose a terahertz wave oscillator using a superconducting layer and an insulating layer stacked on a high-temperature superconductor.

[0004] A structure in which an insulating layer is sandwiched between superconducting layers is known as a Josephson junction. When a voltage is applied across this, a high-frequency current proportional to the applied voltage is generated. This effect is known as the AC Josephson effect. Some single crystals of high-temperature superconductors naturally contain Josephson junctions, known as intrinsic Josephson junctions. Therefore, by applying a voltage to such single crystals, it is possible to generate a high-frequency current based on the AC Josephson effect.

[0005] Furthermore, a technology for improving the oscillation characteristics of this high-temperature superconducting oscillator is proposed in Patent Document 3. Patent Document 3 proposes a structure in which a superconducting element is sandwiched between multiple substrates to release heat generated from the element, as well as a shape in which multiple oscillator elements are sandwiched. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-251863 A [Patent Document 2] JP 2009-43787 A [Patent Document 3] JP 2016-51871 A Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, terahertz waves can be applied to a wide range of fields. It is also known that the terahertz wave oscillators described in the above Patent Documents 1 to 3 can generate electromagnetic waves in the terahertz band. On the other hand, when applying terahertz waves, small and easy-to-use terahertz wave oscillators and terahertz wave detectors are required, but the current situation is that those with sufficient functions have not yet been obtained, which is one of the factors that hinder the development of the application and use of terahertz electromagnetic waves in various industrial fields. In particular, the current situation is that the realization of a small oscillator that obtains a high-intensity monochromatic continuous electromagnetic wave in the vicinity of 1 to 2 terahertz has not yet been achieved, including the terahertz wave oscillators described in Patent Documents 1 to 3.

[0008] In conventional electromagnetic wave oscillators, such as the terahertz wave oscillators described in Patent Documents 1 to 3, a single crystal of a superconductor itself functions as a current generator, a resonator, and an antenna, and emits waves of a specific frequency (terahertz waves) according to the shape and size of the mesa structure formed by the single crystal of the superconductor. However, in conventional electromagnetic wave oscillator structures, where electromagnetic waves are emitted according to the shape and size of the mesa structure formed by a single crystal of a superconductor, there are technical difficulties, such as in terms of processing precision, in order to increase the intensity of the electromagnetic waves.

[0009] Therefore, an object of the present invention is to provide a structure capable of radiating high-intensity electromagnetic waves, a terahertz-band electromagnetic wave oscillation element, and a terahertz-band electromagnetic wave oscillation device. [Means for solving the problem]

[0010] As a result of intensive research into the above-mentioned problems, the inventors have found that it is possible to radiate high-intensity electromagnetic waves by providing a reflection mechanism outside a superconducting element made of a single crystal of a superconductor, reflecting the electromagnetic waves generated from the superconducting element with the reflection mechanism, and feeding back the electromagnetic field to the superconducting element, thereby completing the present invention. That is, the present invention provides a structure, a terahertz-band electromagnetic wave oscillation element, and a terahertz-band electromagnetic wave oscillation device for solving the above problems.

[0011] The structure of the present invention for solving the above problems comprises a superconducting element including a superconductor, a first support substrate, and a second support substrate, the superconducting element, the first support substrate, and the second support substrate being arranged in a stacked manner so as to be electrically conductive in the thickness direction of the superconducting element, and the first and second support substrates each include a reflection mechanism that reflects electromagnetic waves generated from the superconducting element. According to this feature, it is possible to confine the electromagnetic wave by reflecting the electromagnetic wave generated from the superconducting element between the first support substrate and the second support substrate, thereby generating a standing wave between the two support substrates. As a result, the electromagnetic wave is fed back to the superconducting element, improving the phase synchronization of the electromagnetic wave generated by the superconducting element, making it possible to generate high-intensity electromagnetic waves. In addition, the improved phase synchronization of the electromagnetic wave also has the effect of narrowing the linewidth.

[0012] In one embodiment of the structure of the present invention, the superconductor comprises a single crystal of the layered superconductor BSCCO. According to this feature, it is possible to generate electromagnetic waves by utilizing the AC Josephson effect using a single crystal having an intrinsic Josephson junction of a high-temperature superconductor, thereby enabling stable generation of high-frequency electromagnetic waves from a superconducting element.

[0013] In one embodiment of the structure of the present invention, the refractive index of the first and second supporting substrates is not significantly different from the refractive index of the superconducting element. According to this feature, it is possible to suppress the reflection of electromagnetic waves due to the difference in refractive index between the superconducting element and the first and second support substrates, and to efficiently reflect the electromagnetic waves generated by the superconducting element by the reflection mechanism. This makes it possible to generate a stable standing wave, effectively feed back to the superconducting element, and radiate high-intensity electromagnetic waves. In addition, by effectively feeding back to the superconducting element, it is possible to achieve the effect of narrowing the linewidth.

[0014] In addition, as one embodiment of the structure of the present invention, regarding the difference from the refractive index being not large, it is preferable that the absolute value of the difference between the refractive index of the first and second support substrates and the refractive index of the superconducting element is within 30% of the refractive index of the superconducting element. According to this feature, it is possible to further suppress the reflection of electromagnetic waves due to the difference in refractive index between the superconducting element and the first and second support substrates, and to efficiently reflect the electromagnetic waves generated by the superconducting element by the reflection mechanism. This makes it possible to generate stable standing waves, effectively feed back to the superconducting element, and radiate high-intensity electromagnetic waves. In addition, by effectively feeding back to the superconducting element, it is possible to achieve the effect of narrowing the linewidth.

[0015] In one embodiment of the structure of the present invention, the first and second support substrates are insulating or semi-insulating substrates and are characterized in that they have a higher thermal conductivity than the superconducting element. According to this feature, Joule heat generated during operation of the superconducting element can be efficiently dissipated through the first and second support substrates, and current can be efficiently passed through the superconducting element.

[0016] In addition, in one embodiment of the structure of the present invention, the reflection mechanism is characterized in that an area having a refractive index different from the refractive indexes of the first and second support substrates is formed on a surface perpendicular to the stacking direction of the structure. According to this feature, it becomes possible to reflect electromagnetic waves simply by providing areas with different refractive indices, and it becomes possible to easily confine the electromagnetic waves.

[0017] In one embodiment of the structure of the present invention, the reflecting mechanism includes first and second supporting substrates each having a surface coated with a thin metal film. According to this feature, it is possible to reflect electromagnetic waves with a simple structure. Also, by integrating the support substrate and the reflection mechanism, it is easy to reduce the size and cost of the structure. Furthermore, by using a metal thin film with high reflection efficiency, it is possible to effectively confine electromagnetic waves between the first and second support substrates.

[0018] In one embodiment of the structure of the present invention, the reflection mechanism is disposed outside the first and second support substrates and includes a structure that reflects electromagnetic waves. According to this feature, by providing the support substrate and the reflection mechanism as separate bodies, it becomes easy to adjust the range in which the electromagnetic wave is reflected within the structure, which makes it possible to adjust the wavelength of the electromagnetic wave to be confined within the structure.

[0019] In one embodiment of the structure of the present invention, the reflecting mechanism includes a hemispherical surface on one surface of the first and / or second supporting substrate. According to this feature, by using a support substrate having a hemispherical surface as a reflection mechanism, it is possible to integrate the support substrate and the lens when emitting electromagnetic waves to the outside, thereby making it possible to reduce the number of parts.

[0020] In one embodiment of the structure of the present invention, the reflecting mechanism has a feature that the distance from the superconducting element is adjustable. According to this feature, it becomes possible to adjust the positional relationship of the standing wave of the electromagnetic wave formed by the superconducting element and the reflection mechanism, thereby making it possible to adjust the amount of feedback of the electromagnetic wave to the superconducting element.

[0021] One embodiment of the structure of the present invention is characterized in that the first and second support substrates and the superconducting element are formed as a unit, and the units are stacked. According to this feature, by unitizing the support substrate and the superconducting element, it becomes easier to form a structure. In addition, by stacking the units, it becomes easier to synchronize the phases of the electromagnetic waves generated from the multiple superconducting elements contained in the stacked units, making it possible to generate strong electromagnetic waves. Furthermore, by synchronizing the phases of the electromagnetic waves, it is possible to narrow the line width.

[0022] In one embodiment of the structure of the present invention, the first and second support substrates have different thicknesses. According to this feature, it becomes possible to easily adjust the positional relationship of the standing wave of the electromagnetic wave formed by the superconducting element and the reflection mechanism by combining the support substrates, thereby making it possible to adjust the feedback amount of the electromagnetic wave.

[0023] In one embodiment of the structure of the present invention, the superconducting elements are characterized in that they form an array structure in which a plurality of superconducting elements are arranged on a plane. This feature enables phase synchronization of the electromagnetic waves generated between the array structures of superconducting elements, making it possible to generate high-intensity electromagnetic waves. In addition, the phase synchronization of the electromagnetic waves also has the effect of narrowing the linewidth.

[0024] In one embodiment of the structure of the present invention, the superconducting element is characterized in that an array structure in which a plurality of superconducting elements are arranged on a plane is further laminated. According to this feature, the superconducting elements are arranged three-dimensionally, making it possible to generate even stronger electromagnetic waves.

[0025] The terahertz band electromagnetic wave oscillation element of the present invention, which is intended to solve the above problems, has the above-mentioned structure and is characterized in that it oscillates terahertz band electromagnetic waves by utilizing the AC Josephson effect to cause a plurality of Josephson junctions to operate in cooperation. According to this feature, the electromagnetic wave is fed back to the superconducting element by the structure provided with the reflection mechanism, which enables phase synchronization of the electromagnetic wave generated by the superconducting element and enables the generation of high-intensity electromagnetic waves. Therefore, it is possible to significantly improve the oscillation output compared to conventional terahertz-band electromagnetic wave oscillators using superconductors.

[0026] In order to solve the above problem, the terahertz band electromagnetic wave oscillator of the present invention comprises the above-mentioned terahertz band electromagnetic wave oscillator element and a voltage application means, and is characterized in that the voltage application means applies a voltage to the superconducting element via a first support substrate and a second support substrate. According to this feature, the above-mentioned terahertz band electromagnetic wave oscillation element can be operated as a terahertz band electromagnetic wave oscillation device, which can effectively function as an electromagnetic wave oscillation device that oscillates high-frequency and high-intensity electromagnetic waves. Effect of the Invention

[0027] According to the present invention, it is possible to provide a structure capable of emitting high-intensity electromagnetic waves, a terahertz-band electromagnetic wave oscillation element, and a terahertz-band electromagnetic wave oscillation device. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic explanatory diagram (plan view) of a structure according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic explanatory view (plan view) showing another aspect of the structure according to the first embodiment of the present invention. [Diagram 3] FIG. 4 is a schematic explanatory diagram (plan view) of a structure according to a second embodiment of the present invention. [Figure 4] FIG. 11 is a schematic explanatory diagram (plan view) of a structure according to a third embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic explanatory diagram (plan view) of a structure according to a fourth embodiment of the present invention. [Figure 6] FIG. 11 is a schematic explanatory view (plan view) showing another aspect of the structure according to the fourth embodiment of the present invention. [Figure 7] FIG. 13 is a schematic explanatory diagram (plan view) of a structure according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a structure, a terahertz band electromagnetic wave oscillation element, and a terahertz band electromagnetic wave oscillation device according to the present invention will be described in detail with reference to the drawings. The contents and drawings described in the embodiments are merely illustrative for the purpose of easily explaining the features of the present invention, and are not limited thereto, and may be appropriately modified and implemented without departing from the spirit of the present invention. Also, the drawings are schematic, and the ratios of length, width, and thickness may differ from the actual ratios.

[0030] The structure of the present invention is particularly used for mounting a superconducting element. An example of the use of a superconducting element is a terahertz band electromagnetic wave oscillator capable of emitting terahertz waves. An example of the mounting of a superconducting element is a terahertz band electromagnetic wave oscillator.

[0031] [First embodiment] FIG. 1 is a schematic explanatory diagram (plan view) of a structure and a terahertz band electromagnetic wave oscillation device according to a first embodiment of the present invention.

[0032] As shown in Fig. 1, a structure 10A of this embodiment includes a first support substrate 1, a second support substrate 2, a superconducting element 3, a reflection mechanism 4, a silicon hemispherical lens 5, and wiring 6. Also, as shown in Fig. 1, a terahertz band electromagnetic wave oscillator 20 of this embodiment is configured such that an external power source 7 is provided as a current / voltage application means for the wiring 6 in the structure 10A.

[0033] (Structure (Terahertz-band electromagnetic wave oscillator)) The structure 10A of this embodiment generates a standing wave by reflecting electromagnetic waves radiated from a superconducting element 3 made of a superconductor using a reflection mechanism 4, and confines the electromagnetic waves having a resonant frequency determined by the sum of the thicknesses of the superconducting element 3 and the first and second support substrates 1 and 2. As a result, the trapped electromagnetic waves affect the superconducting element 3, optimizing the environment for phase synchronization of the electromagnetic waves generated in the superconducting element 3, making it possible to oscillate electromagnetic waves of the resonant frequency at high intensity.

[0034] As the structure 10A of this embodiment, it is preferable from the viewpoint of utilization that the superconducting element 3 is appropriately arranged so that a direct current and a voltage can be applied thereto, and that electromagnetic waves are oscillated in an appropriate beam shape toward the outside of the first support substrate 1 and the second support substrate 2. As an example, FIG. 1 shows a state in which a silicon hemispherical lens 5 is attached to the right side surface of the second support substrate 2. As a result, electromagnetic waves are oscillated through the silicon hemispherical lens 5. The size of the silicon hemispherical lens 5 is not particularly limited, and can be appropriately set according to the size of the support substrate. For example, a specific example of the structure 10A shown in FIG. 1 is one in which the diameter of the silicon hemispherical lens 5 is 4 mm and the thickness (height) is 2 mm for the second support substrate 2 (length 7 mm × width 7 mm). 1 shows an example of oscillating electromagnetic waves outside the structure 10A, and is not limited thereto. An example other than providing the silicon hemispherical lens 5 is, for example, a structure in which a hemispherical surface is provided on one side of the second support substrate 2 (or the first support substrate 1), and the hemispherical lens and the second support substrate 2 are integrated with the same material. This also has the effect of reducing the number of parts.

[0035] 1, the structure 10A in this embodiment is arranged such that the superconducting element 3 is stacked between the first support substrate 1 and the second support substrate 2. In addition, wiring 6 for introducing a current is connected to the first support substrate 1 and the second support substrate 2. This allows the first support substrate 1, the second support substrate 2, and the superconducting element 3 to be electrically conductive in the thickness direction of the superconducting element 3.

[0036] Each component of the structure 10A will be described below.

[0037] The first support substrate 1 and the second support substrate 2 in this embodiment are provided with wiring 6 for introducing a current to the superconducting element 3 on the respective surfaces, and also serve to support the superconducting element 3 . In this embodiment, the first support substrate 1 and the second support substrate 2 are the same in terms of material, shape, and size, which makes it possible to reduce costs associated with obtaining and processing the support substrates. The wiring 6 arranged on the first support substrate 1 and the second support substrate 2 may be formed from wire such as gold wire or copper wire, or by depositing a thin film of metal or the like by vacuum deposition, sputtering, or the like.

[0038] The first support substrate 1 and the second support substrate 2 in this embodiment are required to allow electromagnetic waves generated by the superconducting element 3 to efficiently transmit through the support substrates. For this reason, it is preferable to use a material that easily transmits electromagnetic waves and has a refractive index that is not significantly different from that of the superconducting element 3 for the first support substrate 1 and the second support substrate 2. More specifically, it is preferable that the absolute value of the difference between the refractive index of the first support substrate 1 and the second support substrate 2 and that of the superconducting element 3 is within 30% of the refractive index of the superconducting element 3. This suppresses reflection of electromagnetic waves due to the difference in refractive index between the superconducting element 3 and the first support substrate 1 and the second support substrate 2, and the electromagnetic waves generated by the superconducting element 3 are efficiently introduced into the reflection mechanism 4.

[0039] In addition, the first support substrate 1 and the second support substrate 2 in this embodiment are required to support the superconducting element 3 and to dissipate heat generated in the superconducting element 3 via the support substrates. For this reason, it is preferable to use a material having a higher thermal conductivity than the superconducting element 3 for the first support substrate 1 and the second support substrate 2. This makes it possible to efficiently dissipate Joule heat generated during operation of the superconducting element 3 via the first support substrate 1 and the second support substrate 2, enabling stable operation of the superconducting element 3.

[0040] Furthermore, the first support substrate 1 and the second support substrate 2 in this embodiment play the role of an introduction portion for applying a direct current and a voltage in the thickness direction of the superconducting element 3. For this reason, it is preferable to use a material having high resistance or insulating properties for the first support substrate 1 and the second support substrate 2. This makes it possible to efficiently pass a current through the superconducting element 3.

[0041] Therefore, it is particularly preferable that the first support substrate 1 and the second support substrate 2 in this embodiment have a refractive index that is not significantly different from that of the superconducting element 3, are high-resistance semiconductor or insulating substrates, and are made of a material having a higher thermal conductivity than that of the superconducting element 3. For example, the superconducting element 3 is a single crystal of the layered superconductor BSCCO (bismuth strontium calcium copper oxide), Bi2Sr2CaCu2O 8+δTaking Bi2212 as an example, it is known that the refractive index of Bi2212 in the terahertz band is 4.2, and the thermal conductivity at room temperature is 1 to 5 W / m·K (hereinafter, the refractive index is referred to as "n" and the thermal conductivity at room temperature as "κ"). Therefore, specific examples of the material of the first support substrate 1 and the second support substrate 2 in this case include semi-insulating gallium-arsenide substrate (n=3.6, κ=55 W / m·K), sapphire substrate (n=3, κ=27 W / m·K), germanium substrate (n=4, κ=640 W / m·K), high-resistance silicon substrate (n=3.4, κ=163 W / m·K), etc., and a material in which the absolute value of the difference in the refractive index between the superconducting element 3 and the support substrate (the first support substrate 1 and the second support substrate 2) is within 30% is preferably used. Although the refractive index difference will be large, it is also possible to use substrates with high thermal conductivity, such as aluminum nitride substrates (n = 2.2, κ = 150 W / m K) and diamond substrates (κ = 2000 W / m K).

[0042] The shape and size of the first support substrate 1 and the second support substrate 2 in this embodiment are not particularly limited, and may be any substrate that can support the superconducting element 3 and sufficiently transmit the electromagnetic waves generated from the superconducting element 3. For example, a specific example of the structure 10A shown in FIG. 1 is one in which the planar parts of the first support substrate 1 and the second support substrate 2 are square, measuring 7 mm long by 7 mm wide, and having a thickness of 0.5 mm. The shape of the planar parts of the first support substrate 1 and the second support substrate 2 is not limited to a square, and may be rectangular or circular. The thickness of the first support substrate 1 and the second support substrate 2 is an important factor in oscillating electromagnetic waves from the structure 10A, but the means for specifying this thickness are not particularly limited. For example, the thickness may be appropriately designed according to the wavelength of the frequency to be confined between the first support substrate 1 and the second support substrate 2, or a thickness that allows electromagnetic waves to transmit may be appropriately selected according to the wavelength and intensity of the electromagnetic waves generated from the superconducting element 3.

[0043] The superconducting element 3 in this embodiment is a superconducting element using a single crystal or polycrystal of a superconductor, and refers to one that forms a plateau shape or a columnar shape. In particular, the superconducting element 3 includes one having a Josephson junction (sometimes called a Josephson element) that utilizes the Josephson effect that occurs when two superconductors are weakly bonded. Note that an example of the structure of such a Josephson element includes a structure in which two superconductors are separated by a metal or insulator layer, a structure in which a narrow constriction or step is formed between two superconductors, and the like.

[0044] A specific example of the superconducting element 3 in this embodiment is one that uses an intrinsic Josephson junction contained in a single crystal of layered superconductor BSCCO (bismuth strontium calcium copper oxide) having multiple stacked Josephson junctions. The BSCCO single crystal may be any that can generate the AC Josephson effect, and an example of such a chemical formula is Bi2Sr2CaCu2O 8+δ (Bi2212) and Bi2Sr2Ca2Cu3O 10+δ (Bi2223) and others.

[0045] The shape of the superconducting element 3 in this embodiment is not particularly limited as long as it is a flat plate or columnar shape. For example, the shape of the upper and lower surfaces of the superconducting element 3 may be other polygonal shapes such as a square or a rectangle, or a circle.

[0046] The superconducting element 3 in this embodiment functions as a current generating source that generates an AC current when a DC current and a voltage are applied to it. Furthermore, the superconducting element 3 itself has a function of a resonator or an antenna determined by its shape, and is therefore capable of emitting electromagnetic waves to the first support substrate 1 and the second support substrate 2.

[0047] 2 is a schematic explanatory diagram (plan view) showing another aspect of the structure 10A in this embodiment. The wiring 6 and the external power source 7 shown in FIG. 1 are omitted in FIG.

[0048] 2, in the first support substrate 1 and the second support substrate 2, the end surfaces on the opposite side to the supported superconducting element 3 are coated with a thin metal film, and metal deposition films 40A and 40B are provided as the reflection mechanism 4. This makes it possible to integrate the support substrates and the reflection mechanism 4 and reflect electromagnetic waves at both ends of the first support substrate 1 and the second support substrate 2. Furthermore, by integrating the respective support substrates (the first support substrate 1 and the second support substrate 2) and the reflection mechanism 4, it becomes easy to reduce the size and cost of the structure 10A. As another example of integrating the support substrate and the reflection mechanism 4, instead of using the silicon hemispherical lens 5 shown in FIG. 2, a second support substrate 2 (or first support substrate 1) having a hemispherical surface is used, and a metal thin film is coated on the second support substrate 2 together with the hemispherical surface. In this case, it is possible to reduce the number of parts. As described above, the support substrate having a hemispherical surface (first support substrate 1 and / or second support substrate 2) has a structure in which the lens used when oscillating electromagnetic waves to the outside is integrated, so that the effect of reducing the number of parts is further exhibited.

[0049] The metal deposition films 40A and 40B in this embodiment function as so-called reflectors. For such metal deposition films 40A and 40B, it is preferable to use a metal having a high reflectance of electromagnetic waves, and more preferably a metal having a high reflectance of electromagnetic waves in the terahertz band. Specific examples of such metals include gold and silver.

[0050] Furthermore, the reflection mechanism 4 in this embodiment needs to transmit a part of the generated electromagnetic wave to the silicon hemispherical lens 5 side. For this reason, it is preferable that the metal evaporated film 40A provided on the first support substrate 1 side and the metal evaporated film 40B provided on the second support substrate 2 side have different transmittances. Here, the transmittance may be replaced with the reflectance. For example, the transmittance of the metal evaporated film 40A may be zero or the reflectance may be approximately 100%, and the transmittance of the metal evaporated film 40B may be a few percent or the reflectance may be in the 90% range. There is no particular limitation on the means for making the transmittance and reflectance of the metal vapor-deposited films 40A and 40B different from each other. For example, the thickness of the metal vapor-deposited film 40B provided on the second support substrate 2 may be made thinner than the thickness of the metal vapor-deposited film 40A provided on the first support substrate 1, or the materials of the metal vapor-deposited films 40A and 40B may be made different from each other. The means for controlling the transmittance of the metal-deposited films 40A and 40B by the thickness of the films is not particularly limited. For example, the thickness of each of the metal-deposited films 40A and 40B may be designed in consideration of the skin depth.

[0051] (Terahertz band electromagnetic wave oscillator) 1, the terahertz band electromagnetic wave oscillator 20 of this embodiment is configured to operate as a terahertz band electromagnetic wave oscillator by providing an external power source 7 as a current / voltage application means to wiring 6 in a structure 10A serving as a terahertz band electromagnetic wave oscillator element. Moreover, the terahertz band electromagnetic wave oscillator 20 of this embodiment preferably includes a temperature control mechanism (not shown).

[0052] The external power source 7 is not particularly limited in its specific configuration as long as it can control the current and voltage applied to the superconducting element 3 inside the structure (terahertz band electromagnetic wave oscillation element) 10A. For example, a programmable power source (variable power source) may be used as the external power source 7. The temperature control mechanism is not particularly limited in its specific configuration as long as it can keep the superconductor constituting the superconducting element 3 at a superconducting transition temperature Tc or lower and control and maintain a temperature range suitable for electromagnetic wave oscillation. An example of the temperature control mechanism is a refrigerator capable of setting the temperature.

[0053] A predetermined voltage is applied to a superconductor (Josephson element) at or below the superconducting transition temperature Tc by the external power supply 7 and the temperature control mechanism, thereby operating the structure (terahertz band electromagnetic wave oscillator) 10A. This makes it possible to obtain electromagnetic waves in the terahertz band from the terahertz band electromagnetic wave oscillator 20. Furthermore, the terahertz band electromagnetic wave oscillator 20 in this embodiment uses intrinsic Josephson junctions of a high-temperature superconductor made of BSCCO single crystal as a configuration in which the structure (terahertz band electromagnetic wave oscillator) 10A utilizes the AC Josephson effect to cause a plurality of Josephson junctions to operate in cooperation, and therefore it is also possible to change the oscillation frequency by controlling the current and voltage applied from the external power supply 7.

[0054] Furthermore, the terahertz band electromagnetic wave oscillator 20 of this embodiment may be provided with a support capable of holding and storing the structure 10A, which allows the structure 10A to stably emit electromagnetic waves. In this case, it is preferable to provide an electromagnetic wave transmission opening in the support, through which the electromagnetic wave can be emitted from the structure 10A and can be incident on the structure 10A. Furthermore, a structure for increasing the efficiency of emission or incidence of the electromagnetic wave may be provided in the electromagnetic wave transmission opening. Examples of such a structure include, for example, using a silicon hemispherical lens 5 provided in the structure 10A as shown in FIG. 1, or providing a focusing lens having a shape and made of a material other than the silicon hemispherical lens 5. This makes it possible to improve the emission efficiency of the electromagnetic wave oscillated from the terahertz band electromagnetic wave oscillator 20 or the incidence efficiency of the electromagnetic wave to the terahertz band electromagnetic wave oscillator 20. Moreover, the terahertz band electromagnetic wave oscillator 20 can be suitably used not only as an oscillator of terahertz band electromagnetic waves but also as a detector of terahertz band electromagnetic waves.

[0055] As described above, by using the structure 10A of this embodiment as a terahertz band electromagnetic wave oscillation element, it is possible to fabricate a terahertz band electromagnetic wave oscillation device 20 capable of oscillating electromagnetic waves at high frequency and high intensity.

[0056] [Second embodiment] FIG. 3 is a schematic explanatory diagram (plan view) showing a structure according to a second embodiment of the present invention.

[0057] As shown in FIG. 3, the structure 10B in this embodiment is the structure 10A in the first embodiment, in which reflectors 41A and 41B are provided on the outer sides of the first support substrate 1 and the second support substrate 2 as a reflection mechanism 4. Note that the description of the same components as those in the first embodiment will be omitted. Also, the wiring 6 and the external power source 7 in the first embodiment are omitted from FIG.

[0058] In the structure 10B of this embodiment, a structure that reflects electromagnetic waves is provided as a reflection mechanism 4 on the outside of the first support substrate 1 and the second support substrate 2, and as shown in Fig. 3, reflection plates 41A and 41B are provided separately from the first support substrate 1 and the second support substrate 2. This makes it easy to adjust the distance between the reflection mechanism 4 and the superconducting element 3, and therefore makes it possible to adjust the wavelength of the electromagnetic waves confined inside the structure 10B.

[0059] In this embodiment, the reflectors 41A and 41B are preferably made of a metal having a high reflectance of electromagnetic waves, and more preferably, a metal having a high reflectance of electromagnetic waves in the terahertz band. Specific examples of such metals include gold and silver. The reflectors 41A and 41B may be any metal that reflects electromagnetic waves on its surface, and may be, for example, a metal structure made of gold or silver, or a non-metal structure coated with gold or silver.

[0060] The shape of the reflectors 41A and 41B in this embodiment is flat as shown in Fig. 3, which has the advantage of being easy to process, but is not limited thereto. Other examples of the shape of the reflectors 41A and 41B include a structure having a concave surface as a shape that exhibits a light collecting effect. Examples of the structure having a concave surface include a structure in which only one of the reflectors 41A and 41B is concave, or a structure in which both of the reflectors are concave.

[0061] The reflectors 41A and 41B in this embodiment preferably have a distance adjustment function for adjusting the distance from the superconducting element 3. More specifically, for example, the reflectors preferably have a function for adjusting the position in the Z direction in Fig. 3. Examples of the distance adjustment mechanism for this purpose include a movable stage, a micrometer, and the like.

[0062] As in the first embodiment described above, the reflection mechanism 4 in this embodiment needs to transmit a part of the generated electromagnetic wave to the silicon hemispherical lens 5. For this reason, it is preferable that the reflector 41A provided on the first support substrate 1 side and the reflector 41B provided on the second support substrate 2 side have different transmittances or reflectances. More specifically, the thickness of the reflector 41B provided on the second support substrate 2 side may be made thinner than the thickness of the reflector 41A provided on the first support substrate 1 side, or the reflectors 41A and 41B may be made of different materials.

[0063] In the structure 10B of this embodiment, the reflection mechanism 4 is provided with a distance adjustment mechanism capable of adjusting the distance from the superconducting element 3, which makes it possible to adjust the positional relationship of the standing wave of the electromagnetic wave formed by the superconducting element 3 and the reflection mechanism 4. This makes it possible to adjust the amount of feedback of the electromagnetic wave to the superconducting element 3. As a result, it is possible to optimize the environment related to the phase synchronization of the electromagnetic wave generated by the superconducting element 3 and improve the radiation intensity of the electromagnetic wave oscillated from the structure 10B.

[0064] [Third embodiment] FIG. 4 is a schematic explanatory diagram (plan view) showing a structure according to a third embodiment of the present invention.

[0065] As shown in Fig. 4, structure 10C in this embodiment is obtained by stacking units 8, which are the first support substrate 1, the second support substrate 2, and the superconducting element 3 in structure 10A in the first embodiment, in an axial direction passing through the centers of the first support substrate 1, the second support substrate 2, and the superconducting element 3. Hereinafter, the stacking direction of units 8 in this embodiment corresponds to the Z direction in Fig. 4. Hereinafter, the stacking direction of units 8 will be referred to as the Z direction. In the structure 10C of this embodiment, the reflection mechanisms 4 are provided on both ends of the stacked units 8. Note that the description of the same components as those in the first embodiment will be omitted. Also, the wiring 6 and the external power source 7 in the first embodiment are omitted from FIG.

[0066] The structure 10C in this embodiment forms a three-dimensional array structure of superconducting elements 3 by stacking units 8, each of which is composed of a first support substrate 1, a second support substrate 2, and a superconducting element 3, in the Z direction. This causes a synchronization phenomenon in which the outputs of electromagnetic waves generated by the superconducting elements 3 are mutually enhanced, making it possible to improve the oscillation output of electromagnetic waves of the superconducting element 3 as a whole. Furthermore, by forming the units 8, the formation of the structures 10C becomes easier.

[0067] 4 shows that metal deposition films 40A and 40B are provided as the reflection mechanism 4, but the present invention is not limited thereto. The reflection mechanism 4 may be any mechanism that reflects electromagnetic waves generated from the superconducting element 3, and may use the above-mentioned reflection plates 41A and 41B.

[0068] 4 shows three units 8 stacked together, but the present invention is not limited to this. By adjusting the number of stacked units 8 in this embodiment, i.e., the thickness in the Z direction, it is possible to adjust the positional relationship between the standing wave of the electromagnetic wave confined in the structure 10C and the superconducting element 3, and adjust the amount of feedback of the electromagnetic wave to the superconducting element 3. As a result, it is possible to optimize the environment related to the phase synchronization of the electromagnetic wave generated in the superconducting element 3, and improve the radiation intensity of the electromagnetic wave oscillated from the structure 10C.

[0069] [Fourth embodiment] FIG. 5 is a schematic explanatory diagram (plan view) showing a structure according to a fourth embodiment of the present invention.

[0070] As shown in FIG. 5, the structure 10D in this embodiment has a first support substrate 1' and a second support substrate 2' with different thicknesses instead of the first support substrate 1 and the second support substrate 2 in the structure 10A in the first embodiment. The first support substrate 1', the second support substrate 2', and the superconducting element 3 are stacked in an axial direction passing through their centers. Hereinafter, the stacking direction of the support substrates 1', 2' and the superconducting element 3 in this embodiment corresponds to the Z direction in FIG. 5. Hereinafter, the stacking direction of the support substrates 1', 2' and the superconducting element 3 will be referred to as the Z direction. In the structure 10D of this embodiment, the reflection mechanisms 4 are provided at both ends of the support substrates 1' and 2' in the Z direction. Note that the description of the same components as those in the first embodiment will be omitted. Also, the wiring 6 and the external power source 7 in the first embodiment are omitted from the illustration in FIG.

[0071] In the structure 10D of this embodiment, a first support substrate 1', a second support substrate 2', and superconducting elements 3 are stacked in the Z direction to form a three-dimensional array structure of superconducting elements 3. This generates a synchronization phenomenon in which the outputs of electromagnetic waves generated by the superconducting elements 3 mutually increase, making it possible to improve the oscillation output of electromagnetic waves of the entire superconducting element 3. In addition, the occurrence of the synchronization phenomenon also has the effect of narrowing the line width.

[0072] 5 shows that metal deposition films 40A and 40B are provided as the reflection mechanism 4, but the present invention is not limited thereto. The reflection mechanism 4 may be any mechanism that reflects electromagnetic waves generated from the superconducting element 3, and may use the above-mentioned reflection plates 41A and 41B.

[0073] In this embodiment, the first support substrate 1' and the second support substrate 2' are such that Z2>Z1 holds when the thickness of the first support substrate 1' is Z1 and the thickness of the second support substrate 2' is Z2 in Figure 5, but this is not limited to this and Z1>Z2 may also hold.

[0074] In the structure 10D of this embodiment, the first support substrate 1 and the second support substrate 2 have different thicknesses, so that the thickness in the Z direction can be easily adjusted with a small number of parts. By adjusting the thickness in the Z direction, the positional relationship between the standing wave of the electromagnetic wave confined in the structure 10D and the superconducting element 3 can be adjusted, and the feedback amount of the electromagnetic wave to the superconducting element 3 can be adjusted. As a result, it is possible to optimize the environment related to the phase synchronization of the electromagnetic wave generated in the superconducting element 3, and improve the radiation intensity of the electromagnetic wave oscillated from the structure 10D. In addition, by optimizing the environment related to the phase synchronization of the electromagnetic wave, an effect of narrowing the line width is also achieved.

[0075] Figure 5 shows, from the left side of the figure, a first support substrate 1 provided with a metal vapor deposition film 40A, a superconducting element 3, a second support substrate 2, a superconducting element 3, a second support substrate 2, a superconducting element 3, and a first support substrate 1 provided with a metal vapor deposition film 40B, but the present invention is not limited to this.

[0076] Fig. 6 is a schematic explanatory diagram (plan view) showing another aspect of the structure 10D in this embodiment. Note that the description of the same configuration as in the first embodiment is omitted. Also, the wiring 6 and the external power source 7 in the first embodiment are omitted in Fig. 6.

[0077] 6, in order to adjust the thickness of the structure 10D in the Z direction, a third support substrate 9 having a thickness different from that of the first support substrate 1' and the second support substrate 2' is provided. This makes it possible to finely adjust the thickness in the Z direction. Here, the reflection mechanism 4 is provided at both ends of the support substrates stacked in the Z direction of the structure 10D. For example, in Fig. 6, the first support substrate 1 is the left end in the Z direction of the structure 10D, so a metal vapor deposition film 40A is provided on the first support substrate 1, while the third support substrate 9 is the right end in the Z direction of the structure 10D, so a metal vapor deposition film 40B is provided on the third support substrate 9. This makes it possible to reflect electromagnetic waves generated from the superconducting element 3 in the Z direction of the structure 10D.

[0078] In this embodiment, the third support substrate 9 is made of the same material as the first support substrate 1 and the second support substrate 2 . Moreover, the thickness Z3 of the third support substrate 9 in this embodiment is determined by Z3=Z2-Z1 (Z2>Z1).

[0079] In the present embodiment, the structure 10D uses a plurality of support substrates with different thicknesses, which allows easy fine adjustment of the thickness of the structure 10D in the Z direction. This makes it possible to optimize the environment related to the phase synchronization of the electromagnetic waves generated by the superconducting element 3, and improve the radiation intensity of the electromagnetic waves oscillated from the structure 10D. In addition, optimizing the environment related to the phase synchronization of the electromagnetic waves also has the effect of narrowing the line width.

[0080] [Fifth embodiment] FIG. 7 is a schematic explanatory diagram (plan view) showing a structure according to the fifth embodiment of the present invention.

[0081] As shown in Figure 7, the structure 10E in this embodiment is obtained by providing a plurality of superconducting elements 3 on a support substrate plane (XY plane in Figure 7) in the structure 10A in the first embodiment to form an array, and then stacking the array of superconducting elements in an axial direction (Z direction in Figure 7) passing through the centers of the first support substrate 1, the second support substrate 2, and the superconducting elements 3. Note that the description of the same configuration as in the first embodiment will be omitted. Also, the wiring 6 and the external power source 7 in the first embodiment are omitted from FIG.

[0082] The structure 10E in this embodiment is capable of increasing the intensity of electromagnetic wave radiation by arranging a plurality of superconducting elements 3 on the XY plane between the first support substrate 1 and the second support substrate 2 to form an array. Moreover, the structure 10E in this embodiment is capable of increasing the intensity of electromagnetic wave radiation and narrowing the oscillation linewidth by further stacking the array in the Z direction. That is, the structure 10E in this embodiment can exhibit various effects by stacking the superconducting elements 3, similar to the structure 10C in the third embodiment and the structure 10D in the fourth embodiment described above.

[0083] 7 shows that metal deposition films 40A and 40B are provided as the reflection mechanism 4, but the present invention is not limited thereto. The reflection mechanism 4 may be any mechanism that reflects electromagnetic waves generated from the superconducting element 3, and may use the above-mentioned reflection plates 41A and 41B.

[0084] As described above, the structure 10E in this embodiment is capable of increasing the intensity of electromagnetic wave radiation and narrowing the oscillation linewidth by arranging the superconducting elements 3 in a two-dimensional or three-dimensional array. The configuration of the structure 10E in this embodiment may be applied to the structure 10B in the second embodiment, the structure 10C in the third embodiment, and the structure 10D in the fourth embodiment, thereby making it possible to increase the intensity of electromagnetic wave radiation and narrow the oscillation linewidth of the structures 10B to 10D in the second to fourth embodiments.

[0085] The above-mentioned embodiments show examples of a structure, a terahertz band electromagnetic wave oscillator, and a terahertz band electromagnetic wave oscillator device. The structure, the terahertz band electromagnetic wave oscillator, and the terahertz band electromagnetic wave oscillator device according to the present invention are not limited to the above-mentioned embodiments, and the structure, the terahertz band electromagnetic wave oscillator, and the terahertz band electromagnetic wave oscillator device according to the above-mentioned embodiments may be modified within a scope that does not change the gist of the claims.

[0086] For example, the reflection mechanism provided in the structure of this embodiment may be a combination of those shown in the first and second embodiments. More specifically, a reflection plate may be provided on the outside of the first support substrate, and a metal deposition film may be provided on the right end surface of the second support substrate. This makes it possible to integrate the reflection mechanism and the support substrate on the second support substrate side, and to easily adjust the position of the reflection mechanism on the first support substrate side. As a result, it is easy to form the structure, and it is also possible to easily adjust the amount of feedback of the electromagnetic wave to the superconducting element. [Industrial Applicability]

[0087] The structure and terahertz band electromagnetic wave oscillation element of the present invention can be suitably used as an electromagnetic wave oscillation element capable of oscillating high-frequency (terahertz band) and high-intensity electromagnetic waves. Furthermore, the terahertz band electromagnetic wave oscillator of the present invention can be applied to spectroscopes and non-destructive imaging devices that utilize electromagnetic waves in the terahertz band, as well as terahertz wave detectors. [Explanation of symbols]

[0088] 10A, 10B, 10C, 10D, 10E Structure, 20 Terahertz band electromagnetic wave oscillator, 1, 1' First support substrate, 2, 2' Second support substrate, 3 Superconducting element, 4 Reflection mechanism, 40A, 40B Metal deposition film, 41A, 41B Reflector, 5 Silicon hemispherical lens, 6 Wiring, 7 External power supply, 8 Unit, 9 Third support substrate

Claims

1. A superconducting element including a superconductor; A first support substrate; A second support substrate, the superconducting element, the first support substrate, and the second support substrate are stacked and arranged so as to be electrically conductive in a thickness direction of the superconducting element; A structure characterized in that the first and second support substrates each have a reflection mechanism on an end surface opposite the superconducting element that reflects electromagnetic waves generated from the superconducting element, and are configured to generate a standing wave between the first and second support plates.

2. 2. The structure of claim 1, wherein the superconductor comprises a single crystal of the layered superconductor BSCCO.

3. 3. The structure according to claim 1, wherein the refractive indexes of the first and second support substrates are not significantly different from the refractive index of the superconducting element.

4. 4. The structure described in claim 3, wherein an absolute value of the difference between the refractive index of the first and second support substrates and the refractive index of the superconducting element is within 30% of the refractive index of the superconducting element.

5. The structure according to any one of claims 1 to 4, characterized in that the first and second support substrates have a higher thermal conductivity than the superconducting element.

6. The structure described in any one of claims 1 to 5, characterized in that the reflection mechanism forms an area having a refractive index different from the refractive index of the first and second support substrates on a surface perpendicular to the stacking direction of the structure.

7. 6. The structure according to claim 1, wherein the reflecting mechanism includes a surface of the first and second support substrates coated with a thin metal film.

8. The structure according to any one of claims 1 to 7, wherein the reflection mechanism includes a hemispherical surface on one side of the first and / or second support substrate.

9. The structure according to any one of claims 1 to 8, characterized in that the reflecting mechanism is adjustable in distance from the superconducting element.

10. 10. The structure according to claim 1, wherein the first and second support substrates and the superconducting element are formed as a unit, and the units are stacked.

11. The structure according to any one of claims 1 to 10, characterized in that the first and second support substrates each have a different thickness.

12. 12. The structure according to claim 1, wherein the superconducting elements form an array structure in which a plurality of the superconducting elements are arranged on a plane.

13. 13. The structure according to claim 1, wherein the superconducting element is further laminated in an array structure in which a plurality of the superconducting elements are arranged on a plane.

14. A structure according to any one of claims 1 to 13, A terahertz-band electromagnetic wave oscillator, characterized in that a plurality of Josephson junctions operate in cooperation with each other by utilizing the AC Josephson effect to generate terahertz-band electromagnetic waves.

15. The terahertz band electromagnetic wave oscillation element according to claim 14; a voltage application means for applying a voltage to the superconducting element via the first and second support substrates.

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