JP6807097B2 - Plasmonic antenna, manufacturing method and detection device for plasmonic antenna - Google Patents

Description

The present invention relates to a plasmonic antenna, a method for manufacturing the plasmonic antenna, and a detection device.

Since the frequency of about 0.3 to 10 terahertz (THz) matches the frequency of the inherent lattice vibration of the substance, the detection device for examining the internal structure of the substance uses electromagnetic waves in the THz band. is there.

For example, using a plasmonic antenna formed on a conductor substrate such as gold having a Bull's Eye (BE) structure in which a plurality of concentric grooves are formed, an incident THz band electromagnetic wave is collected by a surface plasmon having a BE structure. A technique for illuminating has been proposed (see, for example, Non-Patent Document 1). Further, a technique for miniaturizing a plasmonic antenna by arranging a dielectric layer such as silicon on the plasmonic antenna has been proposed (see, for example, Non-Patent Document 2).

O. Mahboub, S. C. Palacios, C. Genet, F. J. Gracia-Vidal, S. G. Rodrigo, L. Martin-Moreno and T.W. Ebbesen, "Optimization of bull's eye structures for transmission enhancement", Opt. Express 18, 11 (2010) Satoshi Ihara, Toshinori Oda, Yukio Kono, "Study on miniaturization of terahertz band plasmonic antenna by FDTD method", 75th JSAP Autumn Meeting, 19p-C6-8 (2014)

Conventionally, when collecting electromagnetic waves of different frequencies, it is necessary to prepare a plasmonic antenna set to the wavelength of the electromagnetic waves to be collected by the intervals of the concentric grooves in the BE structure.

When a dielectric layer such as silicon is arranged on the plasmonic antenna, electromagnetic waves in the THz band incident through the dielectric layer are multiplexed inside the conductor substrate due to the thickness of the conductor substrate of the plasmonic antenna. May be reflected. In this case, the light collection efficiency for electromagnetic waves in the THz band is lowered, and the sensitivity of the plasmonic antenna is lowered.

It is an object of the present invention to provide a plasmonic antenna, a method for manufacturing a plasmonic antenna, and a detection device capable of achieving at least one of widening the electromagnetic wave in the THz band or increasing the sensitivity to the electromagnetic wave in the THz band. And.

One aspect of the plasmonic antenna exemplifying the present invention includes a conductor substrate having a plane on which electromagnetic waves are incident, and the conductor substrate has a plurality of grooves concentrically arranged around a predetermined position on the plane. The interval changes from the interval of the first wavelength to the interval of the second wavelength according to the desired band of the electromagnetic wave to be received from the first wavelength to the second wavelength and the angle centered on the predetermined position.

One aspect of the method for manufacturing a plasmonic antenna exemplifying the present invention is to set a desired band for receiving electromagnetic waves from the first wavelength to the second wavelength and a predetermined position on the plane in a plane of a conductor substrate on which an electromagnetic wave is incident. A plurality of grooves arranged concentrically around a predetermined position on a plane are formed by vapor deposition of metal at intervals that change from the interval of the first wavelength to the interval of the second wavelength according to the angle of the center. ..

One aspect of the detection device illustrating the present invention is a light source that emits electromagnetic waves, and a plasmonic of the present invention that receives electromagnetic waves emitted from the light source, collects the received electromagnetic waves, and irradiates the object to be detected. It includes an antenna and a detection unit that detects electromagnetic waves transmitted through an object.

The present invention can achieve at least one of widening the electromagnetic wave in the THz band or increasing the sensitivity to the electromagnetic wave in the THz band.

It is a figure which shows one Embodiment of a detection device. It is a figure which shows an example of the plasmonic antenna shown in FIG. It is a figure which shows another example of the plasmonic antenna shown in FIG. It is a figure which shows another example of the plasmonic antenna shown in FIG. It is a figure which shows an example of the plasmonic antenna which the groove shown in FIG. 4 is arranged point-symmetrically. It is a figure which shows an example of the manufacturing method of the plasmonic antenna shown in FIG. It is a figure which shows another embodiment of the detection apparatus. It is a figure which shows an example of the plasmonic antenna shown in FIG. 7. It is a figure which shows an example of the manufacturing method of the plasmonic antenna shown in FIG. 7.

Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 shows an embodiment of a detection device.

The detection device 100 shown in FIG. 1 includes a light source 10, a plasmonic antenna 20, and a detection unit 30.

The light source 10 emits electromagnetic waves in the THz band toward the plasmonic antenna 20. The frequency and bandwidth of the electromagnetic wave emitted by the light source 10 are appropriately controlled by, for example, an arithmetic processing device such as a processor included in the detection device 100, or an external computer device connected to the detection device 100. Is preferable.

The plasmonic antenna 20 is, for example, a conductor substrate of a metal such as gold, silver, or copper, and a BE in which a plurality of concentric grooves are formed on the surface of the conductor substrate on which the electromagnetic wave emitted by the light source 10 is incident. Has a structure. Then, the plasmonic antenna 20 collects the electromagnetic wave in the THz band received from the light source 10 at the center of the BE structure by the surface plasmon having the BE structure. The plasmonic antenna 20 irradiates the focused electromagnetic wave in the THz band on the object OBJ to be detected, which is arranged at the center of the BE structure. The plasmonic antenna 20 outputs an electromagnetic wave in the THz band transmitted through the object OBJ to the detection unit 30. The plasmonic antenna 20 will be described with reference to FIGS. 2 to 5.

Although the object OBJ is arranged at the center of the BE structure in the plasmonic antenna 20, it may be arranged between the light source 10 and the plasmonic antenna 20. In this case, the plasmonic antenna 20 receives the electromagnetic wave in the THz band transmitted through the object OBJ, collects the received electromagnetic wave, and outputs the received electromagnetic wave to the detection unit 30.

The detection unit 30 is, for example, a detector such as a photodiode, detects an electromagnetic wave output from the plasmonic antenna 20, and converts it into an electric signal or the like. The detection unit 30 outputs an electric signal to the arithmetic processing unit of the detection device 100 or an external computer device. Then, the arithmetic processing unit of the detection device 100 or the external computer device executes spectrum processing or the like on the received electric signal to analyze the internal structure of the object OBJ such as the lattice vibration peculiar to the object OBJ. To do. Thereby, for example, it is possible to detect a substance-specific absorption spectrum in a non-destructive inspection of a packaged tablet or the like. The detection unit 30 may be integrally formed with the plasmonic antenna 20.

FIG. 2 shows an example of the plasmonic antenna 20 shown in FIG. FIG. 2A shows a plasmonic antenna 20 formed on a plane of a conductor substrate on which electromagnetic waves from the light source 10 are incident. FIG. 2B shows a cross section of the plasmonic antenna 20 in the broken lines A1-A2 shown in FIG. 2A. In FIG. 2, the plane of the conductor substrate on which the plasmonic antenna 20 is formed is defined as the XY plane, perpendicular to the XY plane, and the direction from the plasmonic antenna 20 to the light source 10 is the Z axis.

As shown in FIG. 2B, the plasmonic antenna 20 has, for example, a black region on the XY plane on which the electromagnetic wave is incident, at intervals d1 and d2 according to the reception wavelengths of the electromagnetic waves in the two desired THz bands. It has a BE structure in which a plurality of semicircular grooves 40 and 50 shown by are arranged concentrically. Since the intervals d1 and d2 are wavelengths of electromagnetic waves in the THz band, they have a size of several hundred micrometers.

Further, in the plasmonic antenna 20, a hole HL penetrating in the Z-axis direction is arranged at the center of the grooves 40 and 50 arranged concentrically. Then, the plasmonic antenna 20 collects the electromagnetic wave in the THz band received from the light source 10 toward the hole HL by the surface plasmon having the BE structure, and collects the electromagnetic wave collected through the hole HL to the detection unit 30. Output. As shown in FIG. 1, when the object OBJ is arranged at the position of the hole HL, the plasmonic antenna 20 irradiates the object OBJ with the focused electromagnetic wave and emits the electromagnetic wave transmitted through the object OBJ. Output to the detection unit 30 via the hole HL.

As described above, the plasmonic antenna 20 receives two electromagnetic waves in the THz band having wavelengths corresponding to the intervals d1 and d2 by having the two grooves 40 and 50 arranged at the intervals d1 and d2. be able to.

In the plasmonic antenna 20, the XY plane is divided into two in the Y-axis direction at the center of the hole HL, and the semicircular grooves 40 and 50 are concentrically formed at intervals d1 and d2 in each of the divided regions. Although arranged, the XY plane may be divided into three or more regions at the center of the hole HL. In this case, as in FIG. 2, in each of the divided regions, a plurality of concentric grooves are arranged around the hole HL at intervals corresponding to a desired reception wavelength of the electromagnetic waves in the THz band. As a result, the plasmonic antenna 20 can receive electromagnetic waves having wavelengths of 3 or more. The center of the hole HL is an example of a predetermined position.

Further, in the plasmonic antenna 20, the number of grooves 40 and 50 is set to 3 and 5, but it is appropriately determined according to the required electromagnetic wave reception sensitivity, frequency band, size of the plasmonic antenna 20, and the like. Is preferable.

Further, in the plasmonic antenna 20, pressure is applied to at least one of the X-axis direction and the Y-axis direction based on control by, for example, an arithmetic processing device of the detection device 100 or an external computer device, and the grooves 40 and 50 are formed. The intervals d1 and d2 may be controlled. Alternatively, the plasmonic antenna 20 may have, for example, NEMS (Nano Electro Mechanical Systems), and the intervals d1 and d2 of the grooves 40 and 50 may be controlled by controlling the NEMS by an external computer device or the like. By controlling the intervals d1 and d2 of the grooves 40 and 50, the plasmonic antenna 20 can shift the wavelength of the received electromagnetic wave and adjust the band of the received electromagnetic wave.

Further, the plasmonic antenna 20 is irradiated with electromagnetic waves by an external light source different from the light source 10, and the wavelength of the received electromagnetic waves can be shifted by changing at least one of the dielectric constant and the carrier density in the plasmonic antenna 20. Good.

The plasmonic antenna 20 is made of silicon that functions as a dielectric layer by depositing a metal such as gold on a flat surface of a substrate such as silicon in which an uneven structure corresponding to the grooves 40 and 50 is formed by etching or the like. Etc. may be possessed. Then, due to the refractive index of the arranged dielectric layer, the wavelength of the electromagnetic wave in the THz band propagating in the dielectric layer is shorter than that in the case of propagating in the air. Therefore, the intervals d1 of the grooves 40 and 50, d2 becomes smaller. When the refractive index is n, the groove interval d and the wavelength λ of the received electromagnetic wave in the THz band are related as in the equation (1).

d = λ / n ... (1)
For example, when the dielectric layer is silicon, the refractive index n is 3.41, so the interval d can be made 1/3.41 times smaller than the wavelength λ, and the plasmonic antenna 20 can be miniaturized. Further, since the plasmonic antenna 20 can arrange more grooves 40 and 50 even if it has the same opening area by arranging the dielectric layer, it is in the THz band as compared with the case where there is no dielectric layer. The sensitivity to electromagnetic waves can be improved.

Further, for example, by adjusting the thickness Dz of the dielectric layer in the Z-axis direction based on the equation (2) so that a standing wave of electromagnetic waves is generated in the arranged dielectric layer, the plasmonic antenna 20 Sensitivity can be improved.

Dz = Δ + M × λ'eff / 2… (2)
Note that λ'eff indicates the execution wavelength of the resonance peak wavelength, Δ indicates the minimum thickness at which a standing wave having the wavelength λ'eff can exist, and M indicates a positive integer of 0 or more.

FIG. 3 shows another example of the plasmonic antenna 20 shown in FIG. FIG. 3 shows a plasmonic antenna 20 formed on the XY plane of the conductor substrate on which the electromagnetic wave is incident, as in the case of FIG. 2A. Further, each of the X, Y, and Z axes in FIG. 3 is the same as in the case of FIG.

In the plasmonic antenna 20 shown in FIG. 3, the XY plane is divided into two in the X-axis and Y-axis directions at the center of the hole HL. Then, in each of the divided regions, the grooves 40 or 50 are concentric circles around the hole HL at the same interval d1 or interval d2 according to the wavelength of the received electromagnetic wave as the opposite region at the center of the hole HL. Arranged in a shape.

As described above, the plasmonic antenna 20 shown in FIG. 3 has two grooves 40 and 50 arranged at intervals d1 and d2, so that the two in the THz band having wavelengths corresponding to the intervals d1 and d2, respectively. Can receive two electromagnetic waves.

In the plasmonic antenna 20, the XY plane may be divided into 2N equal parts at the center of the hole HL (N is a natural number of 2 or more). In this case, as in the case of FIG. 3, in each region of the plasmonic antenna 20, grooves are formed around the hole HL at intervals corresponding to the wavelength of the received electromagnetic wave, which is the same as the region facing the center of the hole HL. Are arranged concentrically. As a result, the plasmonic antenna 20 can receive electromagnetic waves having a wavelength of N or more.

Further, in the plasmonic antenna 20, pressure is applied to at least one of the X-axis direction and the Y-axis direction based on control by, for example, an arithmetic processing device of the detection device 100 or an external computer device, and the grooves 40 and 50 are formed. The intervals d1 and d2 may be controlled. Alternatively, the plasmonic antenna 20 may have NEMS, for example, and the intervals d1 and d2 of the grooves 40 and 50 may be controlled by controlling the NEMS by an external computer device or the like. By controlling the intervals d1 and d2 of the grooves 40 and 50, the plasmonic antenna 20 can shift the wavelength of the received electromagnetic wave and adjust the band of the received electromagnetic wave.

Further, the plasmonic antenna 20 is irradiated with electromagnetic waves by an external light source different from the light source 10, and the wavelength of the received electromagnetic waves can be shifted by changing at least one of the dielectric constant and the carrier density in the plasmonic antenna 20. Good.

Further, in the plasmonic antenna 20, the number of grooves 40 and 50 is set to 3 and 5, but it is appropriately determined according to the required electromagnetic wave reception sensitivity, frequency band, size of the plasmonic antenna 20, and the like. Is preferable.

Further, the plasmonic antenna 20 is made of silicon that functions as a dielectric layer by depositing a metal such as gold on a flat surface of a substrate such as silicon in which a structure is formed in an uneven shape corresponding to the grooves 40 and 50 by etching or the like. Etc. may be possessed. As shown in the equation (1), the wavelength of the electromagnetic wave in the THz band propagating in the dielectric layer is shorter than that in the case of propagating in the air due to the refractive index of the arranged dielectric layer. , 50 intervals d1 and d2 can be reduced, and the plasmonic antenna 20 can be miniaturized. Further, since the plasmonic antenna 20 can arrange more grooves 40 and 50 even if it has the same opening area by arranging the dielectric layer, it is in the THz band as compared with the case where there is no dielectric layer. The sensitivity to electromagnetic waves can be improved.

Further, the plasmonic antenna 20 is adjusted by adjusting the thickness Dz of the dielectric layer in the Z-axis direction based on the equation (2) so that a standing wave of electromagnetic waves is generated in the arranged dielectric layer. You may improve the sensitivity of.

FIG. 4 shows another example of the plasmonic antenna 20 shown in FIG. FIG. 4 shows a plasmonic antenna 20 formed on the XY plane of the conductor substrate on which the electromagnetic wave is incident, as in the case of FIG. 2A. Further, each of the X, Y, and Z axes in FIG. 4 is the same as in the case of FIG.

In the plasmonic antenna 20 shown in FIG. 4, for example, at the center of the hole HL, while changing from the positive X-axis direction (angle θ is 0 degrees) to the negative X-axis direction (angle θ is 180 degrees). In addition, a plurality of grooves 40a shown in the black region where the interval changes from d1 to d2 are arranged concentrically. For example, the distance da of the grooves 40a is related to the angle θ as in the equation (3), for example.

da = d1- (d1-d2) (1-cosθ) / 2 ... (3)
That is, the distance da of the grooves 40a continuously changes from d1 to d2 according to the angle θ from the positive X-axis direction. Further, in the plasmonic antenna 20 shown in FIG. 4, the plurality of grooves 40a are arranged axially symmetrical with respect to the straight line shown by the broken line parallel to the X-axis direction passing through the center of the hole portion HL. The plurality of grooves 40a may be arranged point-symmetrically with respect to the center of the hole HL, for example.

FIG. 5 shows an example of the plasmonic antenna 20 in which the grooves 40a shown in FIG. 4 are arranged point-symmetrically. Note that FIG. 5 shows a plasmonic antenna 20 formed on the XY plane of the conductor substrate on which the electromagnetic wave is incident, as in the case of FIG. 4, and each of the X, Y, and Z axes is the same as in the case of FIG. The same is true.

As described above, the plasmonic antenna 20 shown in FIGS. 4 and 5 has a plurality of grooves 40a having a continuous interval da, so that the electromagnetic wave has an electromagnetic wave in a bandwidth from the wavelength λ1 (interval d1) to the wavelength λ2 (interval d2). Can be received. The wavelength λ1 is an example of the first wavelength, and the wavelength λ2 is an example of the second wavelength.

The interval da of the grooves 40a may change from d1 to d2 while the angle θ changes from 0 degrees to 360 degrees.

Further, in the plasmonic antenna 20, pressure is applied to at least one of the X-axis direction and the Y-axis direction based on control by, for example, an arithmetic processing device of the detection device 100, an external computer device, or the like, and the spacing da of the grooves 40a is applied. May be controlled. Alternatively, the plasmonic antenna 20 may have NEMS, for example, and the interval da of the grooves 40a may be controlled by controlling the NEMS by an external computer device or the like. By controlling the interval da of the grooves 40a, the plasmonic antenna 20 can shift the wavelength of the received electromagnetic wave and adjust the band of the received electromagnetic wave.

Further, the plasmonic antenna 20 may shift the wavelength of the received electromagnetic wave by irradiating the electromagnetic wave with an external light source different from the light source 10 or changing the carrier density in the dielectric by the gate voltage.

Further, in the plasmonic antenna 20 shown in FIGS. 4 and 5, the number of grooves 40a is set to 5, but it is appropriate depending on the required electromagnetic wave reception sensitivity, frequency band, size of the plasmonic antenna 20, and the like. It is preferable to be determined.

Further, the plasmonic antenna 20 shown in FIGS. 4 and 5 is made of dielectric by depositing a metal such as gold on a flat surface of a substrate such as silicon in which a concavo-convex structure corresponding to the groove 40a is formed by etching or the like. It may have silicon or the like that functions as a body layer. As shown in the formula (1), the wavelength of the electromagnetic wave in the THz band propagating in the dielectric layer is smaller than that in the case of propagating in the air due to the refractive index of the formed dielectric layer. The interval between the two can be shortened, and the plasmonic antenna 20 can be miniaturized. Further, in the plasmonic antenna 20, since the dielectric layer is arranged, more grooves 40a can be arranged even in the same opening area, so that the sensitivity to electromagnetic waves in the THz band is improved as compared with the case where there is no dielectric layer. be able to.

Further, for example, by adjusting the thickness Dz of the dielectric layer in the Z-axis direction based on the equation (2) so that a standing wave of electromagnetic waves is generated in the arranged dielectric layer, the plasmonic antenna 20 You may improve the sensitivity of.

FIG. 6 shows an example of a method for manufacturing the plasmonic antenna 20 shown in FIG. FIG. 6 shows, for example, a manufacturing method in the case of generating the plasmonic antenna 20 shown in FIG. The plasmonic antenna 20 shown in FIGS. 3 to 5 is also manufactured in the same manner by the method shown in FIG.

In FIG. 6, for example, among the XY planes of a conductor substrate SB such as gold, the XY planes shown by shading other than the grooves 40 and 50 in order to form the grooves 40 and 50 on the XY planes where electromagnetic waves are incident. Is masked with a film MK using a photomask or the like. Note that FIG. 6A shows the XY plane of the conductor substrate SB on which the electromagnetic wave is incident, as in the case of FIG. 2, and FIG. 6B shows the broken lines A1-A2 shown in FIG. 6A. The cross section of the conductor substrate SB at the position is shown.

Next, by depositing a metal such as gold on the flat surface of the conductor substrate SB masked with the film MK of the pattern shown in FIG. 6, the portions of the conductor substrate SB masked with the film MK are formed into grooves 40 and 50. It is formed. Then, the film MK is removed from the conductor substrate SB. Then, in order to form the hole HL, the portion of the conductor substrate SB other than the hole HL is masked with a film using a photomask or the like. The hole HL is formed by etching the conductor substrate SB whose portion other than the hole HL is masked with a film. Then, by removing the film, the plasmonic antenna 20 is generated.

In the embodiment shown in FIGS. 1 to 6, the plasmonic antenna 20 has an interval corresponding to a desired reception wavelength of electromagnetic waves in the THz band in each of a plurality of regions in which the XY plane is divided at the center of the hole HL. It has a plurality of grooves 40, 50 arranged concentrically at d1 and d2. Alternatively, the plasmonic antenna 20 has a plurality of grooves 40a arranged around the hole HL at an interval da that continuously changes according to the wavelength of the electromagnetic wave in the bandwidth from the wavelength λ1 to the wavelength λ2. That is, by arranging a plurality of grooves having different intervals, the plasmonic antenna 20 can receive electromagnetic waves having a desired plurality of wavelengths among the incident electromagnetic waves in the THz band, and can achieve a wide band. it can.

Further, the plasmonic antenna 20 can be made smaller and more sensitive by arranging a dielectric layer such as silicon.

FIG. 7 shows another embodiment of the detection device. Elements having the same or similar functions as those described in FIG. 1 are designated by the same or similar reference numerals, and detailed description thereof will be omitted.

The detection device 100A shown in FIG. 7 has a light source 10, a plasmonic antenna 20a, and a detection unit 30.

The plasmonic antenna 20a includes, for example, a dielectric substrate such as silicon and a conductor layer such as gold, and a plurality of concentric grooves are formed on the plane of the dielectric substrate facing the plane on which electromagnetic waves are incident. It has a bee structure. Then, the plasmonic antenna 20a is emitted by the light source 10 and receives an electromagnetic wave in the THz band that has passed through the object OBJ. The plasmonic antenna 20a collects received electromagnetic waves at the center of the BE structure by surface plasmon due to the BE structure of the conductor layer arranged on the surface on which a plurality of grooves are formed. The plasmonic antenna 20a outputs the focused electromagnetic wave in the THz band to the detection unit 30. The plasmonic antenna 20a will be described with reference to FIG. The plane on which the electromagnetic wave is incident is an example of the first plane. The plane of the dielectric substrate facing the plane on which the electromagnetic wave is incident is an example of the second plane.

Although the object OBJ is arranged between the light source 10 and the plasmonic antenna 20a, it may be arranged between the plasmonic antenna 20a and the detection unit 30. In this case, the plasmonic antenna 20a irradiates the object OBJ with the focused electromagnetic wave in the THz band, and the detection unit 30 receives the electromagnetic wave in the THz band transmitted through the object OBJ.

FIG. 8 shows an example of the plasmonic antenna 20a shown in FIG. FIG. 8A shows a plasmonic antenna 20a formed on a plane of the dielectric substrate facing the plane on which the electromagnetic wave is incident (that is, the plane on which the electromagnetic wave is output to the detection unit 30). Hereinafter, the plane on which the electromagnetic wave is output to the detection unit 30 is also referred to as an “output side plane”. FIG. 8B shows a cross section of the plasmonic antenna 20a in the broken line B1-B2 shown in FIG. 7A. In FIG. 8, the plane of the dielectric substrate on which the plasmonic antenna 20a is formed is the XY plane, perpendicular to the XY plane, and the direction from the plasmonic antenna 20a to the light source 10 is the Z axis.

As shown in FIG. 8B, the plasmonic antenna 20a has a dielectric substrate 110 and a conductor layer 120. The dielectric substrate 110 is, for example, silicon, titanium oxide, or the like, and a plurality of grooves 40b are concentric circles on the XY plane, which is the output side plane, at intervals dc according to the desired reception wavelength of the electromagnetic waves in the THz band to be received. It has a BE structure arranged in a shape.

The conductor layer 120 is, for example, a metal film such as gold, silver, or copper, and is arranged in a layer having a thickness of dt by vapor deposition on the XY plane (output side plane) of the dielectric substrate 110 in which the groove 40b is formed. , Operates as a plasmonic antenna 20a. It is preferable that the film thickness dt of the conductor layer 120 is thinner than half of the width W of the groove 40b so that the groove 40b is not completely filled by the conductor layer 120. Then, the conductor layer 120 is formed as thin as possible by vapor deposition on the XY plane of the dielectric substrate 110 in which the groove 40b is formed in advance, so that the THz band is formed inside the conductor substrate as in Non-Patent Document 2. Multiple reflections of electromagnetic waves can be avoided. As a result, the plasmonic antenna 20a can improve the sensitivity to electromagnetic waves in the THz band by about 200 times as compared with the case of Non-Patent Document 2, for example.

Further, when the dielectric substrate 110 is made of silicon, the refractive index n is 3.41, so that the interval dc can be made 1/3.41 times smaller than the wavelength λ, and the plasmonic antenna 20a can be miniaturized.

Further, in the plasmonic antenna 20a, the number of grooves 40b is set to three, but it is preferably determined as appropriate according to the required electromagnetic wave reception sensitivity, frequency band, size of the plasmonic antenna 20a, and the like.

Further, in the plasmonic antenna 20a, pressure is applied to at least one of the X-axis direction and the Y-axis direction based on control by, for example, an arithmetic processing device of the detection device 100A, an external computer device, or the like, and the spacing dc of the grooves 40b is applied. May be controlled. Alternatively, the plasmonic antenna 20a may have, for example, NEMS, and the interval dc of the grooves 40b may be controlled by controlling the NEMS by an external computer device or the like. By controlling the interval dc of the grooves 40b, the plasmonic antenna 20a can shift the wavelength of the received electromagnetic wave and adjust the band of the received electromagnetic wave. That is, the bandwidth of the plasmonic antenna 20a can be increased.

Further, the plasmonic antenna 20a is irradiated with electromagnetic waves by an external light source different from the light source 10, and the wavelength of the received electromagnetic waves can be shifted by changing at least one of the dielectric constant and the carrier density in the plasmonic antenna 20a. Good.

Further, since the plasmonic antenna 20a has the dielectric substrate 110, the plasmonic antenna 20a can be miniaturized. Further, since the plasmonic antenna 20a has the dielectric substrate 110, more grooves 40c can be arranged even when it has the same opening area, so that it is more sensitive to electromagnetic waves in the THz band than when there is no dielectric layer. Can be improved.

Further, for example, by adjusting the thickness Dz of the dielectric substrate 110 in the Z-axis direction based on the equation (2) so that a standing wave of electromagnetic waves is generated in the arranged dielectric layer, the plasmonic antenna The sensitivity of 20 can be improved.

Further, as shown in FIG. 8, the plurality of grooves 40b formed in the dielectric substrate 110 are formed concentrically with the hole HL as the center. For example, the grooves 40b have the shapes shown in FIGS. 2 to 5. Grooves may be formed.

FIG. 9 shows an example of a method for manufacturing the plasmonic antenna 20a shown in FIG. FIG. 9 shows, for example, a manufacturing method in the case of generating the plasmonic antenna 20a shown in FIG. Even when the plasmonic antenna 20a has the groove of the pattern shown in FIGS. 2 to 5, it is similarly manufactured by the method shown in FIG. Further, elements having the same or similar functions as those described with reference to FIG. 6 are designated by the same or similar reference numerals, and detailed description thereof will be omitted.

In FIG. 9, for example, in the XY plane of the dielectric substrate 110 having the thickness Dz shown in the formula (2), the output side shown by shading other than the groove 40b in order to form the groove 40b on the output side plane. The flat portion is masked with the film MK using a photomask or the like. 9 (a) shows the output side plane of the dielectric substrate 110, and FIG. 9 (b) shows the cross section of the dielectric substrate 110 at the position of the broken line B1-B2 shown in FIG. 9 (a). ..

Next, by etching the dielectric substrate 110 masked with the film MK of the pattern shown in FIG. 9, the silicon in the region shown in white is removed, and the groove 40b shown in FIG. 8 is formed. Then, the film MK is removed from the dielectric substrate 110, and a metal such as gold is deposited on the output side plane of the dielectric substrate 110 in which the groove 40b is formed to form the conductor layer 120 having a film thickness dt. Will be done. Then, in order to form the hole HL, the portion of the conductor layer 120 other than the hole HL is masked with a film using a photomask or the like. The conductor layer 120 of the hole HL is removed by etching the conductor layer 120 whose portion other than the hole HL is masked with a film. Then, by removing the film, the plasmonic antenna 20a is generated.

In the embodiment shown in FIGS. 7 to 9, the plasmonic antenna 20a has a film thickness dt thinner than half the width W of the groove 40b on the output side plane of the dielectric substrate 110 in which the groove 40b is formed. The conductor layer 120 having the above is vapor-deposited. That is, the conductor layer 120 can be arranged thinner than the conventional one by being formed by thin film deposition on the output side plane of the dielectric substrate 110 in which the groove 40b is formed in advance. As a result, the plasmonic antenna 20a can improve the sensitivity of electromagnetic waves in the THz band by about 200 times or more as compared with the conventional one.

Further, the plasmonic antenna 20a receives by changing the interval dc of the grooves 40b by applying pressure in at least one of the X-axis direction and the Y-axis direction based on the control by an external computer device or the like. The wavelength of the electromagnetic wave to be received can be shifted, and the band of the received electromagnetic wave can be adjusted. As a result, the plasmonic antenna 20a can widen the band of the received electromagnetic wave in the THz band.

The above detailed description will clarify the features and advantages of the embodiments. It is intended that the claims extend to the features and advantages of the embodiments as described above, without departing from their spirit and scope of rights. In addition, a person having ordinary knowledge in the technical field should be able to easily come up with any improvements and changes, and there is no intention of limiting the scope of the embodiments having invention to the above-mentioned embodiments. It is also possible to use suitable improvements and equivalents within the scope disclosed in.

10 ... Light source; 20, 20a ... Plasmonic antenna; 30 ... Detection unit; 40, 40a, 40b, 50 ... Groove; 100, 100A ... Detection device; 110 ... Dielectric substrate; 120 ... Conductor layer; HL ... Hole part; MK ... film; OBJ ... object; SB ... conductor substrate

Claims (3)

A conductor substrate having a plane on which electromagnetic waves are incident is provided.
In the conductor substrate, a plurality of grooves are arranged concentrically around a predetermined position on the plane.
The groove spacing is the spacing from the first wavelength to the second wavelength depending on the desired band of the electromagnetic waves to be received from the first wavelength to the second wavelength and the angle centered on the predetermined position. A plasmonic antenna characterized by changing to. On the plane of the conductor substrate on which the electromagnetic wave is incident, the interval between the first wavelength and the desired band of the first to second wavelengths of the electromagnetic wave received and the angle centered on a predetermined position on the plane. A method for manufacturing a plasmonic antenna, which comprises forming a plurality of grooves concentrically arranged around a predetermined position on the plane by vapor deposition of metal at intervals changing from the second wavelength to the second wavelength. .. A light source that emits electromagnetic waves and
The plasmonic antenna according to claim 1, which receives the electromagnetic wave emitted from the light source, collects the received electromagnetic wave, and irradiates the object to be detected.
A detection device including a detection unit that detects the electromagnetic wave transmitted through the object.

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