Terahertz wave reflection unit, reflector and inspection method

Abstract

A terahertz wave reflection unit, reflector and inspection method, the reflection unit comprising: a bottom reflection layer; an intermediate dielectric layer; a top pattern layer, the pattern structure of the top pattern layer protruding from the intermediate dielectric layer; the pattern structure is a rotationally symmetric figure, including a cross shape and four semi-circular rings respectively arranged at the four ends of the cross shape, the cross shape is formed by the intersection of two identical rectangles, the inner and outer sides of the semi-circular ring are respectively tangent to the two long sides of the corresponding rectangle, and the straight side of the semi-circular ring is collinear with one short side of the corresponding rectangle. Through the pattern structure composed of a cross shape and semi-circular rings connected to its four ends, the reflection of terahertz waves with high reflectivity in a wide frequency band is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz functional devices, and particularly to a terahertz wave reflection unit, a reflector and a detection method. Background Art

[0002] Terahertz waves generally refer to electromagnetic waves with a frequency range of 0.1 - 10 THz and a wavelength range of 0.03 - 3 mm. They are located between microwaves and infrared rays in the electromagnetic spectrum and are in the cross - region of electronics and photonics. Due to their special position in the electromagnetic spectrum, they have many special properties different from other bands. In recent years, with the development of the terahertz field, effectively controlling the wavefront of terahertz waves has become one of the research hotspots in terahertz science and technology. Terahertz functional devices can efficiently and multi - dimensionally control the wavefront of terahertz waves, and the terahertz reflector is one of them. It can achieve different controls on electromagnetic waves by adjusting the amplitude and phase of terahertz reflected waves, such as beam deflection, beam shaping, polarization conversion, and beam focusing. It is a key component in systems such as reflective terahertz spectrometers, terahertz radars, and terahertz communications, so it needs to meet requirements such as high reflectivity, wide bandwidth, and higher phase coverage. Currently, the research on terahertz reflection devices is relatively less. Although the widely used metal reflectors can achieve a relatively high reflectivity, their structures are large and heavy, and they cannot effectively control the beam, which is not conducive to miniaturization, integration, and multi - direction transmission.

[0003] Metasurfaces are an emerging two - dimensional artificial sub - wavelength electromagnetic structure with the characteristics of being ultrathin. Its own thickness is only a few tenths of the working wavelength and can be processed using micro - nano processing technology. It has attracted much attention due to its great potential in manipulating electromagnetic waves, versatility, low loss, and ease of fabrication on chips. It can perform multi - degree - of - freedom and effective manipulation of electromagnetic waves through equivalent electromagnetic surface impedance and abrupt phase discontinuity, such as anomalous reflection / refraction, absorption, invisibility, and polarization conversion. The research and development of metasurfaces provide a new technical route for the control of the amplitude, phase, polarization state, and propagation mode of electromagnetic waves and beam shaping, and have important application value for realizing terahertz modulation devices with comprehensive functions.

[0004] With the proposal of the generalized Snell's law, by introducing specific phase changes on a two - dimensional metasurface and using phase compensation on the metasurface to replace the spatially accumulated phase, the effective control of the terahertz wavefront can be achieved. Currently, the terahertz waveband applicable to terahertz reflection control devices based on metasurfaces is narrow, the reflectivity is low, frequency scanning cannot be achieved, and there is a lack of methods for testing performance. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a terahertz wave reflection unit, a reflector and an inspection method.

[0006] A terahertz wave reflection unit provided by the present invention, the reflection unit includes:

[0007] A bottom reflection layer;

[0008] An intermediate dielectric layer;

[0009] A top pattern layer, the pattern structure of the top pattern layer protruding from the intermediate dielectric layer; the pattern structure is a rotationally symmetric figure, including a cross shape and four semi-circular rings respectively arranged at the four ends of the cross shape, the cross shape is formed by the intersection of two identical rectangles, the inner and outer sides of the semi-circular ring are respectively tangent to the two long sides of the corresponding rectangle, and the straight side of the semi-circular ring is collinear with one short side of the corresponding rectangle.

[0010] According to the terahertz wave reflection unit provided by the present invention, the length of the long side of the rectangle is 29-34 μm, and correspondingly, the length of the short side of the rectangle is 5-7 μm.

[0011] For example, the length of the long side of the rectangle is 29-34 μm, and the length of the short side is 5-7 μm. The terahertz wave reflection unit of this size has better reflection efficiency and a wider reflection bandwidth.

[0012] Preferably, the length of the long side of the rectangle is 32 μm, and the length of the short side is 5 μm. The terahertz wave reflection unit of this size has better reflection efficiency and reflection bandwidth.

[0013] According to the terahertz wave reflection unit provided by the present invention, the thickness of the top pattern layer is 200-400 nm; and / or, the thickness of the intermediate dielectric layer is 25-35 μm; and / or, the thickness of the bottom reflection layer is 200-400 nm; and / or, the cross-sections of the intermediate dielectric layer and the bottom reflection layer are both rectangles with side lengths of 80-90 μm. The terahertz wave reflection unit of this size has better reflection efficiency and a wider reflection bandwidth.

[0014] Furthermore, the thickness of the top pattern layer is 400 nm, the thickness of the intermediate dielectric layer is 30 μm, and the thickness of the bottom reflection layer is 400 nm. The terahertz wave reflection unit of this size has better reflection efficiency and reflection bandwidth.

[0015] A terahertz wave reflection unit provided according to the present invention, wherein both the bottom reflection layer and the top pattern layer are made of metal, and the metal includes one or more of gold, silver, copper or aluminum; and / or, the material of the intermediate dielectric layer is one or more of silicon, quartz or polyimide. The terahertz wave reflection unit with this material structure has better reflection efficiency and a wider reflection bandwidth.

[0016] Preferably, the conductivity of the top metal pattern and the bottom metal layer is 4.56×10 7 S / m. The terahertz wave reflection unit with this material structure has better reflection efficiency and a wider reflection bandwidth. Further, when the metal is gold, the terahertz wave reflection unit has better reflection efficiency and reflection bandwidth.

[0017] Further, the dielectric constant of the intermediate dielectric layer is 3 - 4, and the loss tangent angle is tanδ = 0.01 - 0.1. The terahertz wave reflection unit with this intermediate dielectric layer has better reflection efficiency and a wider reflection bandwidth.

[0018] Preferably, the dielectric constant of the intermediate dielectric layer is 3.5, and the loss tangent angle is tanδ = 0.01. The terahertz wave reflection unit with this intermediate dielectric layer has better reflection efficiency and reflection bandwidth.

[0019] For a terahertz wave reflection unit provided according to the present invention, for vertically incident terahertz waves, in the frequency range of 0.50 - 2.00 THz, the reflectivity of the reflection unit is above 90%.

[0020] The present invention also provides a terahertz wave reflector, which includes a plurality of specifications of reflection units as described in any one of the above, arranged in a periodic sequence.

[0021] For a terahertz wave reflection unit provided according to the present invention, the reflection units are arranged in ascending order of specifications, and the difference between different specifications lies only in the outer radius R1 and the inner radius R2 of the semi - ring. By arranging the reflection units in ascending order of specifications, vertically incident terahertz waves can be reflected in different directions with a very high reflectivity. Through theoretical analysis and calculation using the generalized Snell's reflection law, it can be obtained that within the working frequency band, as the frequency of the incident wave changes, the reflection angle will change accordingly, and the frequency - scanning function can be achieved.

[0022] For a terahertz wave reflector provided according to the present invention, the reflection unit includes five specifications. Correspondingly, the R1 and the R2 are respectively: 7.5 μm and 2.5 μm, 9 μm and 4 μm, 11 μm and 6 μm, 13 μm and 8 μm, 17 μm and 12 μm. Through the above parameter structure, a better frequency - scanning function can be achieved.

[0023] It should be noted that through the CST simulation software, the three parameters of the long side L of the rectangle of the reflection unit, the outer radius R1 and the inner radius R2 of the semi-circular ring are simulated, and the reflectivity and reflection phase curves are obtained in the range of 0.50 - 2.00 THz to determine the reflection characteristics of the terahertz wave reflector, thereby obtaining the required parameters and saving the cost of sample manufacturing.

[0024] According to a terahertz wave reflector provided by the present invention, for the vertically incident terahertz wave, the reflector can achieve a phase difference change of up to 300°.

[0025] According to a terahertz wave reflector provided by the present invention, for the vertically incident terahertz wave, as the frequency of the incident wave increases, the angle of the reflection beam of the reflector gradually decreases.

[0026] The present invention also provides a method for inspecting a terahertz wave reflection unit and a reflector, and the inspection method includes:

[0027] Using photolithography and etching methods, transfer the pattern on the mask plate to the surface of the polyimide substrate to prepare any one of the terahertz wave reflection units and any one of the terahertz wave reflectors as samples;

[0028] Using a terahertz time-domain spectroscopy system to obtain the spectral information of the sample in the range of 0 - 3.0 THz to realize quantitative detection of the reflection characteristics of the reflection unit and the reflector.

[0029] According to a method for inspecting a terahertz wave reflector provided by the present invention, the use of the terahertz time-domain spectroscopy system to obtain the spectral information of the sample in the range of 0 - 3.0 THz to realize quantitative detection of the reflection characteristics of the reflection unit and the reflector includes the following steps:

[0030] Using the terahertz time-domain spectroscopy system, in the reflection measurement mode, in a nitrogen environment, collect the terahertz spectral data of the metal mirror as a reference signal, collect the terahertz spectral data of the reflection unit and the reflector as sample signals, and perform Fourier transform on the time-domain spectrum to obtain the reference amplitude and the sample amplitude;

[0031] In the range of 0 - 3.0 THz, using the amplitude information, use the ratio of the sample amplitude to the reference amplitude as the reflectivity of the reflection unit, and obtain the frequency-reflectivity curve of the reflector.

[0032] According to a method for inspecting a terahertz wave reflector provided by the present invention, the measurement conditions when the terahertz time-domain spectroscopy system collects signals are: 20 - 25 °C, relative humidity < 10%.

[0033] The terahertz wave reflection unit, reflector and inspection method provided by the present invention achieve high reflectivity of terahertz waves with a wide frequency band through a pattern structure composed of a cross and semi-circular rings connected to its four ends. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 Schematic diagram of a terahertz wave reflection unit structure provided in Embodiment 1 of the present invention;

[0036] Figure 2 Simulation result of the TM wave vertically incident in Embodiment 1 of the present invention;

[0037] Figure 3 Structural parameters of different reflection units provided by the present invention;

[0038] Figure 4 Reflectivity curve graph of the TM wave vertically incident on the reflector in Embodiment 2 of the present invention;

[0039] Figure 5 Phase difference curve graph of the TM wave vertically incident on the reflector in Embodiment 2 of the present invention;

[0040] Figure 6 Schematic diagram of a terahertz wave reflector structure provided by the present invention;

[0041] Figure 7 Schematic diagram of the results of the TM wave vertically incident on the reflector in Embodiment 3 of the present invention with frequencies of f = 1.00 THz, f = 1.30 THz, and f = 1.60 THz respectively;

[0042] Figure 8 Schematic diagram of the results of verifying the frequency sweep performance of the reflector by using electromagnetic simulation software in Embodiment 4 of the present invention;

[0043] Figure 9 Reflectivity test result graph of reflectors of the same specification in Embodiment 5 of the present invention;

[0044] Figure 10 Reflectivity test result graph of the terahertz wave reflector in Embodiment 5 of the present invention. Detailed Description of the Invention

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the accompanying drawings of the present invention. Apparently, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0046] The following will, with reference to the accompanying drawings, elaborate on the terahertz wave reflection unit provided in the embodiments of the present application through specific embodiments and their application scenarios.

[0047] Embodiment 1

[0048] In this embodiment, an electromagnetic simulation software is used to design and simulate and provide a terahertz wave reflection unit. Figure 1 FIG. is a schematic structural diagram of a terahertz wave reflection unit provided in Embodiment 1 of the present invention. Figure 1 In FIG., b is a side view of the reflection unit. As shown in b in FIG., the terahertz wave reflection unit includes, from bottom to top: a bottom reflection layer, an intermediate dielectric layer, and a top pattern layer. Figure 1 Among them, the cross-section of the bottom reflection layer is square, with a side length of 85 μm and a thickness of 0.2 μm, and the material is gold.

[0049] Among them, the cross-section of the intermediate dielectric layer is square, with a side length of 85 μm and a thickness of 30 μm, and the material is polyimide.

[0050] Among them, the top pattern layer has a thickness of 0.2 μm.

[0051] In FIG., a is a top view of the top pattern layer. As shown in a in FIG., the pattern structure of the top pattern layer protrudes from the intermediate dielectric layer; the pattern structure is a rotationally symmetric figure (rotation angle 90°), including a cross shape and four semi-circular rings respectively arranged at the four ends of the cross shape. The cross shape is formed by the intersection of two identical rectangles. The inner and outer sides of the semi-circular ring are respectively tangent to the two long sides of the corresponding rectangle, the straight side of the semi-circular ring is collinear with one short side of the corresponding rectangle, and the rectangle and the semi-circular ring are in the same plane. The outer radius length R1 of the semi-circular ring is 7.5 μm, the inner radius length R2 is 2.5 μm, the long side length L of the rectangle is 32 μm, and the short side length of the rectangle is 5 μm. Figure 1 In FIG., a is a top view of the top pattern layer. As shown in a in FIG., the pattern structure of the top pattern layer protrudes from the intermediate dielectric layer; the pattern structure is a rotationally symmetric figure (rotation angle 90°), including a cross shape and four semi-circular rings respectively arranged at the four ends of the cross shape. The cross shape is formed by the intersection of two identical rectangles. The inner and outer sides of the semi-circular ring are respectively tangent to the two long sides of the corresponding rectangle, the straight side of the semi-circular ring is collinear with one short side of the corresponding rectangle, and the rectangle and the semi-circular ring are in the same plane. The outer radius length R1 of the semi-circular ring is 7.5 μm, the inner radius length R2 is 2.5 μm, the long side length L of the rectangle is 32 μm, and the short side length of the rectangle is 5 μm. Figure 1 In FIG., a is a top view of the top pattern layer. As shown in a in FIG., the pattern structure of the top pattern layer protrudes from the intermediate dielectric layer; the pattern structure is a rotationally symmetric figure (rotation angle 90°), including a cross shape and four semi-circular rings respectively arranged at the four ends of the cross shape. The cross shape is formed by the intersection of two identical rectangles. The inner and outer sides of the semi-circular ring are respectively tangent to the two long sides of the corresponding rectangle, the straight side of the semi-circular ring is collinear with one short side of the corresponding rectangle, and the rectangle and the semi-circular ring are in the same plane. The outer radius length R1 of the semi-circular ring is 7.5 μm, the inner radius length R2 is 2.5 μm, the long side length L of the rectangle is 32 μm, and the short side length of the rectangle is 5 μm.

[0052] For the terahertz wave reflection unit of this embodiment, Figure 2 FIG. is the simulation result of the TM wave vertically incident in Embodiment 1 of the present invention. As shown in FIG., in the frequency range of 0.50 - 2.00 THz, its reflectivity is above 90%, and the applicable bandwidth reaches 1.50 THz. Figure 2 In FIG., a is a top view of the top pattern layer. As shown in a in FIG., the pattern structure of the top pattern layer protrudes from the intermediate dielectric layer; the pattern structure is a rotationally symmetric figure (rotation angle 90°), including a cross shape and four semi-circular rings respectively arranged at the four ends of the cross shape. The cross shape is formed by the intersection of two identical rectangles. The inner and outer sides of the semi-circular ring are respectively tangent to the two long sides of the corresponding rectangle, the straight side of the semi-circular ring is collinear with one short side of the corresponding rectangle, and the rectangle and the semi-circular ring are in the same plane. The outer radius length R1 of the semi-circular ring is 7.5 μm, the inner radius length R2 is 2.5 μm, the long side length L of the rectangle is 32 μm, and the short side length of the rectangle is 5 μm.

[0053] Example 2

[0054] Based on the terahertz wave reflection unit provided in Example 1, in this example, an electromagnetic simulation software is used for design and simulation to provide a broadband terahertz wave reflector with discontinuous phase change. A plurality of reflection units are provided on the substrate surface. Figure 6 As shown in the structural schematic diagram of a terahertz wave reflector provided by the present invention, Figure 6 as shown, the reflection unit can form various different specifications of reflection units by changing R1 and R2, where R1 is the outer radius of the semi-circular ring and R2 is the inner radius of the semi-circular ring. In this example, 5 different specifications of reflection units are obtained with R1 and R2 as adjustment parameters (R1 = 7.5 μm and R2 = 2.5 μm, R1 = 9 μm and R2 = 4 μm, R1 = 11 μm and R2 = 6 μm, R1 = 13 μm and R2 = 8 μm, and R1 = 17 μm and R2 = 12 μm).

[0055] For these 5 reflection units, the present invention conducts simulations of TM wave perpendicular incidence. Figure 4 As shown in the reflectivity curve graph of the simulation of the reflector with TM wave perpendicular incidence in Example 2 of the present invention, Figure 4 as shown, it shows that these five reflection units have a very high reflectivity within the entire working bandwidth and the change in reflectivity of each reflection unit is very small; Figure 5 As shown in the phase difference curve graph of the simulation of the reflector with TM wave perpendicular incidence in Example 2 of the present invention, Figure 5 as shown, it shows that the phase curves of the five reflection units have good linearity. The phase difference between the first reflection unit and the second reflection unit is between 46° - 86°, the phase difference between the second reflection unit and the third reflection unit is between 60° - 77°, the phase difference between the third reflection unit and the fourth reflection unit is between 40° - 70°, the phase difference between the fourth reflection unit and the fifth reflection unit is between 50° - 60°, and the phase difference between the first reflection unit and the fifth reflection unit is between 240° - 300°. Therefore, a discontinuous phase change of 300° can be achieved within the entire bandwidth.

[0056] Example 3

[0057] Based on the broadband terahertz wave reflector with discontinuous phase change provided in the foregoing example, in this example, an electromagnetic simulation software is used for design and simulation to verify its performance. The structure of the reflector is as Figure 6 shown, Figure 3 As shown in the structural parameters of different reflection units provided by the present invention, Figure 3 and 6As shown, five types of reflection units form a period (“the first type of reflection unit” - “the fifth type of reflection unit”), and are arranged periodically in sequence along the x-axis direction on the substrate to obtain a broadband terahertz high reflector with discontinuous phase change. The distance between adjacent terahertz wave reflection units within each period is 85 μm.

[0058] For this broadband terahertz high reflector with discontinuous phase change, in this embodiment, TM waves with frequencies of f = 1.00 THz, f = 1.30 THz, and f = 1.60 THz are respectively vertically incident. Figure 7 It is a schematic diagram of the results when the reflectors in Embodiment 3 of the present invention are respectively vertically incident with TM waves with frequencies of f = 1.00 THz, f = 1.30 THz, and f = 1.60 THz. As Figure 7 shown, for this terahertz wave reflector, when the incident wave is a right-handed circularly polarized wave vertically incident, the terahertz waves are reflected in different directions at different frequencies. As Figure 7 shown in a and b of Figure 7 , when the frequency of the incident wave is f = 1.00 THz, the reflection angle is approximately 44°; as Figure 7 shown in c and d of

[0059] Embodiment 4

[0060] Based on the broadband terahertz wave reflector with discontinuous phase change provided in Embodiment 2, Figure 8 It is a schematic diagram of the results of verifying the frequency sweep performance of the reflector by using electromagnetic simulation software in Embodiment 4 of the present invention. As Figure 8 shown, for this broadband terahertz wave reflector with discontinuous phase change, in this embodiment, TM waves with frequencies of 1.00 THz, 1.10 THz, 1.20 THz, 1.30 THz, 1.40 THz, 1.50 THz, and 1.60 THz are respectively vertically incident. For this broadband terahertz wave reflector with discontinuous phase change, when the incident wave is a TM wave vertically incident, the corresponding reflection angles of the reflected waves are 44°, 39°, 35°, 31°, 29°, 27°, and 25° respectively. Therefore, as the frequency of the incident wave increases, the angle of the reflected beam gradually decreases, demonstrating good beam scanning characteristics. According to Snell's law, Where θ is the reflection angle, λ is the wavelength of the terahertz wave, and Γ is the physical length of one coding sequence period of the metasurface. Here, substituting Г = 5×85 = 425μm into the formula, the corresponding reflection angles are 44.91°, 39.94°, 36.02°, 31.96°, 30.26°, 28.10°, and 26.23° when the incident frequencies are 1.00 THz, 1.10 THz, 1.20 THz, 1.30 THz, 1.40 THz, 1.50 THz, and 1.60 THz respectively. It can also be seen from the figure that as the reflection frequency increases, the number of scattered beams increases and the reflectivity of the main beam gradually decreases, which is basically consistent with the theory, and at the same time verifies the generalized Snell's law.

[0061] Example 5

[0062] Based on the terahertz wave reflection unit provided in Example 1 and the broadband terahertz wave reflector with discontinuous phase change provided in Example 2, in this example, an L-Edit is used to draw a mask processing drawing, and an effective and usable terahertz wave reflection unit and terahertz wave reflector are processed through ultraviolet lithography technology. Among them, to test the reflection unit, an array of 200×200 identical said reflection units constitutes a reflector with the same specification of reflection units. The terahertz wave reflector is composed of a total of 170×170 five coding elements arranged in a periodic sequence in the x direction, and the size parameters are the same as those used in the simulation. The specific steps for its detection are as follows:

[0063] Apply a terahertz time-domain spectroscopy system based on a photoconductive antenna. The indoor temperature is 22°C, the humidity is less than 10%, and the terahertz frequency range is 0 - 3.0 THz. Using the terahertz time-domain spectroscopy system, the terahertz time-domain signal of a metal mirror measured in a nitrogen-filled environment in the reflection measurement mode is used as a reference signal, and the time-domain signals of the reflector with the same specification and the terahertz wave reflection device measured are used as sample signals, and the obtained time-domain spectra are Fourier-transformed to obtain the reference amplitude E ref (ω) and the sample amplitude E sam (ω), r = E sam (ω) / E ref (ω) is the reflectivity. Figure 9 This is the reflectivity test result diagram of the reflector with the same specification in Example 5 of the present invention. As Figure 9 shown, in the frequency range of 0.50 - 1.60 THz, the reflectivity of the unit is above 80%, the bandwidth is 1.10 THz, and it has a very high reflectivity in a very wide frequency range; Figure 10 This is the reflectivity test result diagram of the terahertz wave reflector in Example 5 of the present invention. As Figure 10As shown, in the frequency range of 0.20 - 1.50 THz, the reflectivity of the reflector is above 80%, and the bandwidth reaches 1.30 THz. In addition, the phase coverage of the terahertz wave reflector in this actual test reaches 270°, which is very close to 300° in the simulation. This proves that whether in simulation or testing, the reflectivity of the reflection unit and the device is very high, and the working bandwidth is also very wide.

[0064] Based on the theory of coded metasurface, the present invention designs a coded metasurface terahertz wave reflector. This metasurface flexibly controls terahertz waves by changing the different structural parameters and unit arrangement orders of the designed reflection units, and with the same reflector, the function of reflecting incident terahertz waves in different directions can be achieved. The terahertz wave reflector is prepared by using photolithography and etching technologies, and the terahertz time-domain spectroscopy system is used to test the device in the reflection mode and nitrogen environment. The terahertz time-domain spectroscopy signal is obtained as the sample signal, and the time-domain spectroscopy signal of the metal mirror detected under the same conditions is used as the reference signal. Then, the reflection spectrum of the sample within the characteristic frequency is obtained by using Fourier transform, and a quantitative analysis model is established by using the data fitting method to obtain the quantitative detection value of the sample to be measured.

[0065] Based on specific terahertz wave reflection units, the present invention arranges them periodically to obtain a wide-band terahertz wave reflector with discontinuous phase change. The structure of the terahertz wave reflection unit and its device preparation are simple, with a small volume, and can adopt micro-nano processing technology, and the processing cost and difficulty are low; the wide-band terahertz wave reflector device with discontinuous phase change has a relatively wide working bandwidth, a very high reflectivity within the working frequency range, and can achieve a discontinuous phase change of 300°; the terahertz wave reflection device adopts the principle of coded metasurface and has more degrees of freedom in the regulation of terahertz waves; the terahertz wave reflection unit and the terahertz wave reflection device have great potential application value in terahertz communication, terahertz reflection imaging, beam control, etc.

[0066] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative labor.

[0067] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A terahertz wave reflection unit, characterized in that, The reflection unit includes: A bottom reflection layer; An intermediate dielectric layer; A top pattern layer, the pattern structure of the top pattern layer protruding from the intermediate dielectric layer; the pattern structure is a rotationally symmetric figure, including a cross shape and four semi-circular rings respectively arranged at the four ends of the cross shape, the cross shape is formed by the intersection of two identical rectangles, the inner and outer sides of the semi-circular ring are respectively tangent to the two long sides of the corresponding rectangle, and the straight side of the semi-circular ring is collinear with one short side of the corresponding rectangle; The quantitative detection of the terahertz wave reflection unit includes: using the terahertz time-domain spectroscopy system, adopting the reflection measurement mode, in a nitrogen environment, collecting the terahertz spectral data of the metal mirror as the reference signal, collecting the terahertz spectral data of the reflection unit as the sample signal, performing Fourier transform on the time-domain spectrum to obtain the reference amplitude and the sample amplitude; in the range of 0 - 3.0 THz, using the amplitude information, taking the ratio of the sample amplitude to the reference amplitude as the reflectivity of the reflection unit.

2. The terahertz wave reflection unit according to claim 1, wherein The length of the long side of the rectangle is 29 - 34 μm, correspondingly, the length of the short side of the rectangle is 5 - 7 μm.

3. The terahertz wave reflection unit according to claim 1, characterized in that The thickness of the top pattern layer is 200 - 400 nm; and / or, the thickness of the intermediate dielectric layer is 25 - 35 μm; and / or, the thickness of the bottom reflection layer is 200 - 400 nm; and / or, the cross-sections of the intermediate dielectric layer and the bottom reflection layer are both rectangles with side lengths of 80 - 90 μm.

4. The terahertz wave reflection unit according to claim 1, characterized in that, Both the bottom reflection layer and the top pattern layer are made of metal, the metal includes one or more of gold, silver, copper or aluminum; and / or, the material of the intermediate dielectric layer is one or more of silicon, quartz or polyimide.

5. The terahertz wave reflection unit according to any one of claims 1-4, characterized in that, For the vertically incident terahertz wave, in the frequency range of 0.50 - 2.00 THz, the reflectivity of the reflection unit is above 90%.

6. A terahertz wave reflector, characterized in that, The reflector includes a periodic sequence arrangement of multiple specifications of the reflection unit as described in any one of claims 1 - 5.

7. The terahertz wave reflector according to claim 6, characterized in that, The reflection units are arranged in ascending order of specification, and the difference between different specifications lies only in the outer radius R1 and the inner radius R2 of the semi-circular ring.

8. The terahertz wave reflector according to claim 7, characterized in that, The reflection unit includes five specifications, correspondingly, the R1 and the R2 are respectively: 7.5 μm and 2.5 μm, 9 μm and 4 μm, 11 μm and 6 μm, 13 μm and 8 μm, 17 μm and 12 μm.

9. The terahertz wave reflector according to any one of claims 6-8, characterized in that, For the vertically incident terahertz wave, the reflector can achieve a phase difference change of up to 300°.

10. The terahertz wave reflector according to any one of claims 6-8, characterized in that, For the vertically incident terahertz wave, as the frequency of the incident wave increases, the angle of the reflected beam of the reflector gradually decreases.

11. A terahertz wave reflection unit and a reflector inspection method, characterized in that, The inspection method includes: Using photolithography and etching methods, transferring the pattern on the mask plate to the surface of the polyimide substrate to prepare the terahertz wave reflection unit as described in any one of claims 1 - 5 and the terahertz wave reflector as described in any one of claims 6 - 8 as samples; The spectral information of the sample in the range of 0 - 3.0 THz is obtained by using a terahertz time-domain spectroscopy system to quantitatively detect the reflection characteristics of the reflection unit and the reflector. Specifically: Using the terahertz time-domain spectroscopy system, in the reflection measurement mode, under a nitrogen environment, the terahertz spectral data of the metal mirror is collected as a reference signal, and the terahertz spectral data of the reflection unit and the reflector is collected as sample signals. The time-domain spectrum is Fourier-transformed to obtain the reference amplitude and the sample amplitude. In the range of 0 - 3.0 THz, using the amplitude information, the ratio of the sample amplitude to the reference amplitude is used as the reflectivity of the reflection unit, and the frequency-reflectivity curve of the reflector is obtained.

12. The terahertz wave reflection unit and reflector inspection method according to claim 11, characterized in that, The measurement conditions when the terahertz time-domain spectroscopy system collects signals are: 20 - 25 °C, relative humidity < 10%.

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