Terahertz wave output device and sensing device

Abstract

A terahertz wave output apparatus (20) comprises: a radiation layer (2) that radiates electromagnetic waves of a terahertz band; a reflection layer (4) that is disposed behind the radiation layer to reflect the electromagnetic waves of the terahertz band; and an intermediate layer (3) which is positioned between the radiation layer and the reflection layer and is transmissive to the electromagnetic waves of the terahertz band. The terahertz wave output apparatus (20) causes the radiation layer to radiate a first wave (WF), which is an electromagnetic wave of the terahertz band, forwardly of the radiation layer, and to radiate a second wave (WS), which is an electromagnetic wave of the terahertz band, rearwardly of the radiation layer, the terahertz wave output apparatus (20) outputting a terahertz wave (WT) in which a reflection wave (WR) obtained by forward reflection of the second wave is superimposed with the first wave. In the terahertz wave output apparatus, the intensity of the terahertz wave (output wave) can be increased by setting the characteristics of the intermediate layer so that the reflection wave and the first wave are positively superimposed.

Description

[Technical Field]

[0001] The present disclosure relates to a terahertz wave output device. [Background technology]

[0002] Terahertz waves are expected to be a next-generation elemental technology, for example, for use in sixth-generation mobile communication systems (6G). Patent Document 1 discloses a technology for increasing the intensity by overlapping the irradiation areas of two terahertz waves. [Prior art documents] [Patent documents]

[0003] Patent Document 1: Japanese Patent Publication No. 2022- 898 issue” bulletin Summary of the Invention [Problem to be solved by the invention]

[0004] The technique disclosed in Patent Document 1 has a problem in that the intensity of terahertz waves cannot be increased efficiently. [Means for solving the problem]

[0005] A terahertz wave output device according to one aspect of the present disclosure includes an emission layer that emits electromagnetic waves in the terahertz band, a reflection layer that is disposed behind the emission layer and reflects the electromagnetic waves in the terahertz band, and an intermediate layer that is disposed between the emission layer and the reflection layer and transmits the electromagnetic waves in the terahertz band.

[0006] A terahertz wave output method according to one aspect of the present disclosure includes radiating a first wave, which is an electromagnetic wave in the terahertz band, forward from an emission layer, and radiating a second wave, which is an electromagnetic wave in the terahertz band, backward from the emission layer, and outputting a terahertz wave in which the first wave is superimposed on light reflected forward from the second wave. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, the intensity of terahertz waves is efficiently increased. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a configuration example of a terahertz wave output device according to an embodiment of the present invention. [Figure 2] 5A to 5C are schematic diagrams illustrating the operation of the terahertz wave output device of the present embodiment. [Figure 3] 2 is a perspective view showing an example of the configuration and function of the radiation layer 2. FIG. [Figure 4] 1 is a schematic diagram showing a configuration example of a terahertz wave output device according to an embodiment of the present invention; [Figure 5] 1 is a graph showing an example of a first wave from a radiation layer. [Figure 6] 10 is a graph showing an example of reflected light. [Figure 7] 10 is a graph showing a case where the first wave and the reflected wave constructively interfere with each other. [Figure 8] 10 is a graph showing terahertz waves output when a first wave and a reflected wave constructively interact with each other. [Figure 9] 10 is a graph showing a difference in output intensity between the terahertz wave output device according to the present embodiment and a comparative example. [Figure 10] FIG. 1 is a block diagram showing the configuration of a sensing device using a terahertz wave output device. [Figure 11] FIG. 10 is a perspective view showing another example of the configuration of the terahertz wave output device of the present embodiment. [Figure 12] FIG. 10 is a cross-sectional view showing another configuration of the terahertz wave output device of the present embodiment. [Figure 13] FIG. 10 is a cross-sectional view showing another configuration of the terahertz wave output device of the present embodiment. [Figure 14] FIG. 10 is a cross-sectional view showing another configuration of the terahertz wave output device of the present embodiment. [Figure 15] FIG. 10 is a cross-sectional view showing another configuration of the emissive layer of the present embodiment. [Figure 16] FIG. 10 is a cross-sectional view showing another configuration of the emissive layer of the present embodiment. [Figure 17]FIG. 10 is a cross-sectional view showing another configuration of the emissive layer of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Fig. 1 is a perspective view showing an example of the configuration of a terahertz wave output device of this embodiment. Fig. 2 is a schematic diagram showing the operation of a terahertz wave output device of this embodiment. As shown in Figs. 1 and 2, a terahertz wave output device 20 includes an emission layer 2 that emits electromagnetic waves in the terahertz band, a reflection layer 4 that is disposed behind the emission layer 2 and reflects electromagnetic waves in the terahertz band, and an intermediate layer 3 that is disposed between the emission layer 2 and the reflection layer 4 and transmits electromagnetic waves in the terahertz band.

[0010] The terahertz wave output method of this embodiment radiates a first wave WF, which is an electromagnetic wave in the terahertz band, forward from the radiation layer 2, and radiates a second wave WS, which is an electromagnetic wave in the terahertz band, backward from the radiation layer, and outputs a terahertz wave WT obtained by superimposing reflected light WR, which is obtained by forward reflecting the second wave, on the first wave WF.

[0011] The terahertz band is, for example, 0.05 to 50 THz, and the output terahertz waves WT are electromagnetic waves in this frequency band. "Forward" refers to the direction in which the terahertz waves WT are output. The emission layer 2 may be the emission section (electromagnetic wave generation section) 2, the intermediate layer 3 may be the intermediate section 3, and the reflective layer 4 may be the reflective section 4.

[0012] The radiation layer 2 radiates a first wave WF in the terahertz band forward, radiates a second wave WS in the terahertz band backward, and outputs a terahertz wave WT forward, which is generated by superimposing a reflected wave WR generated when the second wave WS is reflected by the reflective layer 4 on the first wave WF. In the terahertz wave output device 20, for example, the intensity of the terahertz wave WT (output wave) can be increased by setting the characteristics of the intermediate layer 3 so that the reflected wave WR and the first wave WF are positively superimposed.

[0013] (radiative layer) FIG. 3 is a perspective view showing an example of the configuration and operation of the radiation layer 2. As shown in FIG. 3, the radiation layer 2 has a first layer 11, which is a magnetic layer containing a magnetic metal, and a second layer 12, which is a non-magnetic layer containing a non-magnetic metal, and is also called an STE (spintronic terahertz emitter). The first and second layers 11 and 12 are stacked with the first layer 11 facing forward, but this is not limitative. The first layer 11 may also be stacked with the first layer 11 facing backward.

[0014] The magnetic metal contained in the first layer 11 may be a ferromagnetic metal. The first layer 11 may be composed of an element or compound containing at least one of Fe (iron), Co (cobalt), Ni (nickel), and Gd (gadolinium). One example is Fe. The first layer 11 may contain at least one of CoFeB and GdFe. The thickness of the first layer 11 may be 1 to 20 nm. One example is 5 nm.

[0015] The second layer 12 may be composed of a simple substance or a compound containing at least one of Pt (platinum), Au (gold), Ru (ruthenium), Cu (copper), Ta (tantalum), Pd (lead), W (tungsten), and Al (aluminum). One example is Pt. As the nonmagnetic metal constituting the second layer 12, a metal with a large spin-orbit interaction can be used. The thickness of the second layer 12 can be 1 to 20 nm. One example is 5 nm.

[0016] The STE-based emitting layer 2 emits electromagnetic waves in the terahertz band upon receiving excitation light LK. The excitation light LK is, for example, a discontinuous-wave laser beam (infrared pulsed laser beam) with a wavelength of approximately 800 nm. As shown in Figure 3, when the emitting layer 2 is irradiated with femtosecond pulsed laser light, spin polarization occurs at the interface between the first and second layers 11 and 12. The spin current Js flowing between the first and second layers 11 and 12 is converted into a real current Jc flowing parallel to the interface between the first and second layers 11 and 12 (the inverse spin-Hall effect). As a result, terahertz electromagnetic waves corresponding to the real current Jc are emitted in a direction intersecting the interface between the first and second layers 11 and 12. An external magnetic field may be applied to the first layer 11. The STE-based emitting layer 2 has several advantages, including high intensity, a large area, a wide bandwidth, low cost, and a high damage threshold.

[0017] (reflective layer) The reflective layer 4 is a layer that reflects the second wave WS, which is an electromagnetic wave in the terahertz band, and can be made of, for example, a conductor or a dielectric. An example of a conductor is indium tin oxide (ITO) with a thickness of 50 nm to 2.0 μm. An example of the sheet resistance is 6 Ω / sq. When the excitation light LK is incident on the emission layer 2 from behind, as shown in FIG. 2, a light-transmitting material such as ITO is preferable. In addition to ITO, indium zinc oxide (IZO) or an AgMg alloy (an ultra-thin metal film with light transmittance) may also be used. An insulating material with a high refractive index can be used as the dielectric. Note that when the excitation light LK is incident on the emission layer 2 from the front (described later), the light transmittance of the reflective layer 4 is not important.

[0018] (middle class) The intermediate layer 3 is a layer that transmits electromagnetic waves in the terahertz band and can be composed of, for example, a dielectric. The dielectric can be an inorganic insulator such as silicon oxide, silicon nitride, or sapphire, or an organic insulator such as resin, with a thickness of approximately 1.0 to 500 μm. An example is glass (e.g., microsheet glass) or transparent resin with a thickness of 10 to 100 μm. The intermediate layer 3 desirably has a lower refractive index for electromagnetic waves in the terahertz band than the reflective layer 4. The intermediate layer 3 is a phase control layer that controls the phases of the second wave WS and the reflected wave WR. At least one of the refractive index and thickness (of electromagnetic waves in the terahertz band) is set according to the desired (to-be-output) frequency of the terahertz wave WT (described in detail below). The intermediate layer 3 may also perform phase control to align the phases of the first wave WF and the reflected wave WR (i.e., the first wave WF and the reflected wave WR are coherently coupled, thereby enhancing the electromagnetic wave intensity). When the excitation light LK is incident on the emission layer 2 from the rear as shown in FIG. 2, it is desirable that the intermediate layer 3 be optically transparent. However, when the excitation light LK is incident on the emission layer 2 from the front (described later), the optical transparency of the intermediate layer 3 is not an issue.

[0019] The emissive layer 2, intermediate layer 3, and reflective layer 4 are laminated in this order. The intermediate layer 3 may be sandwiched between a substrate on which the emissive layer 2 is formed and a substrate on which the reflective layer 4 is formed. Alternatively, a substrate on which the emissive layer 2 is formed may be disposed on top of the intermediate layer 3 on which the reflective layer 4 is formed. The emissive layer 2 may be formed on one surface of the intermediate layer 3, and the reflective layer 4 may be formed on the other surface.

[0020] Fig. 4 is a schematic diagram showing a configuration example of a terahertz wave output device of this embodiment. In Fig. 1 and Fig. 2, excitation light LK is irradiated from the rear of the terahertz wave output device 20, and the excitation light LK transmitted through the reflective layer 4 and the intermediate layer 3 is incident on the emission layer 2 (second layer 12), but this is not limiting. As shown in Fig. 4, excitation light LK may be irradiated from the front of the terahertz wave output device 20, and the excitation light LK may be directly incident on the emission layer 2 (first layer 11).

[0021] (1st and 2nd wave superposition) FIG. 5 is a graph showing an example of the first wave from the emitting layer. FIG. 6 is a graph showing an example of an assumed reflected light. Here, a 3 nm Fe film is used as the first layer 11, a 3 nm Pt film is used as the second layer 12, a 500 nm ITO film is used as the reflective layer 4, and a 30 μm thick sheet glass is used as the intermediate layer 3. The excitation light LK, which is femtosecond pulsed laser light (wavelength: 800 nm), is irradiated onto the emitting layer 2 from behind. In FIG. 5, the first wave WF is a pulse wave. In FIG. 6, the reflected light WR is assumed to have an amplitude approximately 30% smaller than the first wave WF, and the pulse position (time axis) is delayed by 0.32 picoseconds. This corresponds to approximately 70% transmission of the terahertz-band electromagnetic wave through the emitting layer 2 and a round-trip time of 0.32 picoseconds through the intermediate layer 3.

[0022] The speed at which electromagnetic waves in the terahertz band travel through the intermediate layer 3 is the speed of light c / n (n is the refractive index of the intermediate layer for electromagnetic waves in the terahertz band). If the thickness of the intermediate layer 3 is d, then 2d = speed of light c × 0.32 × 10 -12 / n. Considering that the phases of the first wave WF and the reflected wave WR are shifted by 0.9π to 1.1π (e.g., substantially π) due to fixed-end reflection, the condition under which the first wave WF and the reflected wave WR coherently constructively interact is 2nd = (N + 1 / 2)λ, where f is the frequency of the first and second waves WF·WS and the reflected wave WR, λ is their wavelength (= the speed of light c / f), and N is a natural number. If N = 0, then f = 1.56 [THz], and therefore the terahertz wave output device 20 in this case is suitable for outputting 1.56 [THz] terahertz waves. The condition under which the first wave WF and the reflected wave WR destructively interact is 2nd = Nλ, and therefore, if N = 1, then f = 3.13 [THz]. By setting the thickness of the intermediate layer 3 according to the frequency of the terahertz wave (output wave), the first wave WF and the reflected wave WR can be positively superimposed.

[0023] In this way, the intermediate layer 3 may perform phase control so that the reflected wave WR and the first wave WF that have passed through the intermediate layer 3 and the radiation layer 4 become coherent, and if the first wave WF and the reflected wave WR are pulse waves, the pulse of the first wave WF and the pulse of the reflected wave WR are positively superimposed in front of the radiation layer 2. The product of the refractive index n of the intermediate layer 3 with respect to the second wave WS and the thickness d of the intermediate layer 3 is equal to or greater than ¼ wavelength (λ / 4) of the second wave WS.

[0024] (Effects of this embodiment) FIG. 7 is a graph showing a case where the first wave and the reflected wave constructively interact with each other. FIG. 8 is a graph showing terahertz waves output when the first wave and the reflected wave constructively interact with each other. It can be seen from FIGS. 7 and 8 that the amplitude AT of the output terahertz wave WT is about 1.4 times the amplitude AF of the first wave WF. FIG. 9 is a graph showing the difference in output intensity between the terahertz wave output device according to this embodiment and the comparative example. It can be seen from FIG. 9 that the terahertz wave output device 20 can obtain an output intensity that is about 2.4 times that of the comparative example (output intensity when only the emitting layer is used).

[0025] (Applications and Modifications) FIG. 10 is a block diagram showing the configuration of a sensing device using a terahertz wave output device. As shown in FIG. 10, the sensing device 70 includes a light source 10 of excitation light LK, a terahertz wave output device 20, a detection device 30, an imaging device 40 (e.g., a photodiode or a CMOS camera) that detects the light output from the detection device 30, and a display device 50 that displays video data from the imaging device 40. In the sensing device 70, the terahertz waves WT from the terahertz wave output device 20 are irradiated onto the target TG, and the terahertz waves that have passed through the target TG are input to the detection device 30, whereby a see-through image of the target TG is displayed on the display device 50. The terahertz wave output device 20 and the light source 10 of the excitation light LK can also be integrated (as a single device). Furthermore, the terahertz wave output device 20 and a magnetic field device that applies an external magnetic field to the emission layer 2 can also be integrated (as a single device).

[0026] FIG. 11 is a perspective view showing another example of the configuration of the terahertz wave output device of this embodiment. The radiation layer 2 in FIG. 11 includes a first layer 11, which is a magnetic layer containing a magnetic metal, a second layer 12, which is a non-magnetic layer containing a non-magnetic metal, and a third layer 13, which is a non-magnetic layer containing a non-magnetic metal. The third layer 13 is located forward of the first layer 11. That is, the third layer 13, the first layer 11, and the second layer 12 are stacked in this order. This configuration allows terahertz-band electromagnetic waves to be emitted from the interface between the third layer 13 and the first layer 11 and the interface between the second layer 12 and the first layer 11, thereby further increasing the output (intensity of the terahertz waves) of the terahertz wave output device. The third layer 13 may be composed of a simple substance or compound containing at least one of Pt (platinum), Au (gold), Ru (ruthenium), Cu (copper), Ta (tantalum), Pd (lead), W (tungsten), and Al (aluminum).

[0027] Fig. 12 is a cross-sectional view showing another configuration of the terahertz wave output device of this embodiment. As shown in Fig. 12, a terahertz wave output device 20 may be configured by monolithically forming an emitting layer 2, an intermediate layer 3, and a reflective layer 4 in this order on a substrate 6. For example, a glass substrate can be used for the substrate 6, STE can be used for the emitting layer 2, a resin (e.g., a coatable transparent resin) can be used for the intermediate layer 3, and a light-transmitting conductive film (e.g., ITO, IZO, etc.) or a high-refractive-index insulating film can be used for the reflective layer 4.

[0028] Fig. 13 is a cross-sectional view showing another configuration of the terahertz wave output device of this embodiment. As shown in Fig. 13, an emission layer 2 may be formed on one surface of an intermediate layer 3 having a substrate function, and a reflection layer 4 may be formed on the other surface of the intermediate layer 3. For example, STE may be used as the emission layer 2, glass or resin (e.g., polyimide) may be used as the intermediate layer 3 also serving as the substrate, and a light-transmitting conductive film (e.g., ITO, IZO, etc.) or a high-refractive-index insulating film may be used as the reflection layer 4.

[0029] Fig. 14 is a cross-sectional view showing another configuration of the terahertz wave output device of this embodiment. As shown in Fig. 14, a plano-convex lens 7 having a convex surface 7S and a flat surface 7F may be used as a substrate, and an emitting layer 2, an intermediate layer 3, and a reflective layer 4 may be monolithically formed in this order on the flat surface 7F. In this way, terahertz waves converged by the plano-convex lens 7 can be obtained. An emitting layer 2 (STE) may be provided on the convex surface 7S.

[0030] FIG. 15 is a cross-sectional view showing another configuration of the radiation layer of this embodiment. The radiation layer 2 is not limited to the STE described above. As shown in FIG. 15, the radiation layer 2 may have a photoconductive antenna structure. The radiation layer 2 of the photoconductive antenna structure includes a photoelectric layer (semiconductor layer) 14 formed on a substrate 8, electrodes D1 and D2 formed on the photoelectric layer 14, an antenna A1 electrically connected to the electrode D1 and in contact with the photoelectric layer 14, and an antenna A2 electrically connected to the electrode D2 and in contact with the photoelectric layer 14. When excitation light LK (e.g., pulsed laser light) is received in the gap between the opposing antennas A1 and A2, the radiation layer 2 emits electromagnetic waves in the terahertz band. The intermediate layer 3 can be provided on the substrate 8 side or on the opposite side of the substrate 8. The substrate 8 may also be used as the intermediate layer 3. The radiation layer 2 of the photoconductive antenna structure has advantages such as high efficiency and a wide bandwidth.

[0031] FIG. 16 is a cross-sectional view showing another configuration of the emission layer of this embodiment. As shown in FIG. 16, a nonlinear optical crystal 16 may be used in the emission layer 2. The nonlinear optical crystal 16, such as LiNbO3 (lithium niobate crystal), receives excitation light LK and emits electromagnetic waves in the terahertz band. The intermediate layer 3 may be provided on one side or the other side of the nonlinear optical crystal 16. The emission layer 2 using the nonlinear optical crystal 16 has advantages such as high coherence, high output, and a wide bandwidth.

[0032] FIG. 17 is a cross-sectional view showing another configuration of the emission layer of this embodiment. As shown in FIG. 17, the emission layer 2 may have a resonant tunneling diode (RTD) structure. The emission layer 2 of the RTD structure includes an insulating layer 17 formed on a substrate 9 and a quantum well semiconductor layer 18 located in a hole formed in the insulating layer 17. Applying a voltage to the quantum well semiconductor layer 18 emits electromagnetic waves in the terahertz band. Multiple quantum well semiconductor layers 18 may be formed in an array. For example, when a substrate 9 containing InP is used, n-InP / n-InGaAs or InGaAs / InAlAs may be used as the quantum well semiconductor layer 18. The intermediate layer 3 may be provided on the substrate 9 side or on the opposite side of the substrate 9. The substrate 9 may also be used as the intermediate layer 3. When the emission layer 2 has an RTD structure, excitation light does not need to be irradiated.

[0033] <Summary> As described above, the present disclosure includes the following aspects.

[0034] The terahertz wave output device according to the first aspect of the present disclosure includes an emission layer that emits electromagnetic waves in the terahertz band, a reflection layer that is disposed behind the emission layer and reflects the electromagnetic waves in the terahertz band, and an intermediate layer that is disposed between the emission layer and the reflection layer and transmits the electromagnetic waves in the terahertz band.

[0035] According to the above configuration, it is possible to output a terahertz wave obtained by superimposing an electromagnetic wave in the terahertz band radiated forward from the radiation layer and an electromagnetic wave in the terahertz band radiated backward from the radiation layer and reflected by the reflection layer.

[0036] The terahertz wave output device in aspect 2 of the present disclosure is the same as in aspect 1, in that the radiation layer radiates a first wave in the terahertz band forward and a second wave in the terahertz band backward, and outputs a terahertz wave forward that is generated by superimposing the first wave and a reflected wave generated when the second wave is reflected by the reflection layer.

[0037] The terahertz wave output device according to a third aspect of the present disclosure is the terahertz wave output device according to the first or second aspect, wherein the intermediate layer has insulating properties or high transparency to terahertz waves.

[0038] A terahertz wave output device according to a fourth aspect of the present disclosure is any one of the first to third aspects, wherein the reflective layer has a higher refractive index for electromagnetic waves in the terahertz band than the intermediate layer.

[0039] A terahertz wave output device according to a fifth aspect of the present disclosure is the terahertz wave output device according to the second aspect, wherein the product of the refractive index of the intermediate layer with respect to the second wave and the thickness of the intermediate layer is equal to or greater than ¼ wavelength of the second wave.

[0040] In the terahertz wave output device according to a sixth aspect of the present disclosure, in the second aspect, the reflected wave has a phase shift of approximately 0.9π to 1.1π with respect to the first wave.

[0041] A terahertz wave output device according to a seventh aspect of the present disclosure is the terahertz wave output device according to the second aspect, wherein the intermediate layer performs phase control so that the reflected wave and the first wave that have passed through the intermediate layer and the radiation layer become coherent.

[0042] The terahertz wave output device according to an eighth aspect of the present disclosure is the terahertz wave output device according to the second aspect, wherein at least one of the refractive index of the intermediate layer with respect to the second wave and the thickness of the intermediate layer is set according to the terahertz frequency to be output.

[0043] A terahertz wave output device in aspect 9 of the present disclosure is any one of aspects 1 to 8, wherein the radiation layer includes a first layer which is a magnetic layer containing a magnetic metal, and a second layer which is a non-magnetic layer containing a non-magnetic metal and is in contact with the first layer, and the radiation layer is irradiated with discontinuous oscillation laser light.

[0044] A terahertz wave output device according to a tenth aspect of the present disclosure is the ninth aspect, wherein the reflective layer and the intermediate layer are light-transmitting, and the laser light is irradiated onto the emission layer from behind.

[0045] A terahertz wave output device according to an eleventh aspect of the present disclosure is the terahertz wave output device according to the tenth aspect, wherein the reflective layer includes a conductive layer such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0046] A twelfth aspect of the present disclosure provides the terahertz wave output device of the tenth or eleventh aspect, wherein the intermediate layer is a microsheet glass or a microsheet plastic.

[0047] A thirteenth aspect of the present disclosure provides the terahertz wave output device of the second aspect, wherein the first wave and the reflected wave are pulse waves, and the pulse of the first wave and the pulse of the reflected wave are superimposed in front of the emission layer.

[0048] A terahertz wave output method according to a fourteenth aspect of the present disclosure includes radiating a first wave, which is an electromagnetic wave in the terahertz band, forward from an emission layer, and radiating a second wave, which is an electromagnetic wave in the terahertz band, backward from the emission layer, and outputting a terahertz wave in which the first wave is superimposed on the reflected light obtained by forward reflecting the second wave.

[0049] The above disclosure is intended for purposes of illustration and description, not for purposes of limitation. Based on these examples and descriptions, many variations will be obvious to those skilled in the art, and it should be noted that these variations are also included in the embodiments. [Explanation of symbols]

[0050] 2 Radiation Layer 3. Middle class 4 reflective layer 20 Terahertz wave output device LK excitation light WF 1st wave WS 2nd wave WT terahertz wave (output wave)

Claims

1. an emission layer including a first layer which is a magnetic layer containing a magnetic metal and a second layer which is a non-magnetic layer containing a non-magnetic metal and is in contact with the first layer, the first layer and the second layer each having a thickness of 1 to 20 nm, and which receives excitation light from a pulsed laser beam and emits electromagnetic waves in the terahertz band; a reflection layer disposed behind the emission layer and reflecting the terahertz band electromagnetic waves emitted from the emission layer; an intermediate layer located between the emitting layer and the reflecting layer, the intermediate layer transmitting electromagnetic waves in the terahertz band; the radiation layer radiates a first wave in the terahertz band forward, radiates a second wave in the terahertz band backward, and outputs a terahertz wave forward that is generated by superimposing a reflected wave generated when the second wave is reflected by the reflection layer on the first wave.

2. an emission layer including a first layer which is a magnetic layer containing a magnetic metal and a second layer which is a non-magnetic layer containing a non-magnetic metal and is in contact with the first layer, the first layer and the second layer each having a thickness of 1 to 20 nm, and which receives excitation light from a pulsed laser beam and emits electromagnetic waves in the terahertz band; a reflection layer disposed behind the emission layer and reflecting the terahertz band electromagnetic waves emitted from the emission layer; an intermediate layer located between the emitting layer and the reflecting layer, the intermediate layer transmitting electromagnetic waves in the terahertz band; The intermediate layer is 2nd = (1 / 2)λ The terahertz wave output device has a thickness set so that: (where, n: refractive index of the intermediate layer with respect to electromagnetic waves in the terahertz band emitted from the emission layer d: thickness of the intermediate layer λ: the wavelength of the first wave in the terahertz band radiated forward from the radiating layer, the second wave in the terahertz band radiated backward, and the reflected wave generated when the second wave is reflected by the reflective layer)

3. The reflective layer is translucent, and the excitation light from behind passes through the reflective layer and the intermediate layer and is irradiated onto the emission layer; The terahertz wave output device according to claim 1 , wherein the radiation layer and the reflection layer face each other via the intermediate layer.

4. the first wave and the reflected wave are pulse waves, 3. The terahertz wave output device according to claim 1, wherein the reflected wave has a phase shift of 0.9π to 1.1π with respect to the phase of the first wave.

5. A sensing device using the terahertz wave output device according to claim 1 or 2, a light source of excitation light that excites the emissive layer, the terahertz wave output device, a detection device, an imaging device that senses an output from the detection device, and a display device that displays data from the imaging device; A sensing device that irradiates a target with terahertz waves from the terahertz wave output device, and inputs the terahertz waves irradiated onto the target into the detection device, thereby displaying data regarding the target on the display device.

Images