Terahertz angle sensor based on metamaterial surface spring type structure

Abstract

The application discloses a terahertz angle sensor based on a surface spring type structure of metamaterials, relates to the technical field of terahertz, and solves the problem of large frequency shift caused by the incidence angle of terahertz waves, so that the quality factor and sensitivity of the terahertz angle sensor are improved, and a good linear relationship can be maintained, and the technical scheme is as follows: a base; and a unit structure composed of a first structure and two oppositely placed second structures arranged on the surface of the base in a spring type structure; wherein the first structure is arranged on the surface of the base, and the two oppositely placed second structures are located in the first structure and perpendicular to each other. The terahertz angle sensor based on the surface spring type structure of metamaterials has the advantages of good quality factor, high sensitivity and high linearity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of terahertz, more particularly, it relates to a terahertz angle sensor based on a surface spring type structure of metamaterial. BACKGROUND

[0002] Terahertz waves (THz) are electromagnetic waves with a frequency range of 0.1-10 THz, which coincide with millimeter waves in the long-wave band and with infrared light in the short-wave band.

[0003] A terahertz angle sensor is a passive device with directionality and plays an important role in various terahertz circuit systems. At present, many sensor researches in the terahertz frequency band are based on the insensitivity of the terahertz wave incidence angle, while the terahertz angle sensor is a highly sensitive sensor device based on the angle.

[0004] At present, the traditional angle measurement method is to use an angle measuring scale or a laser angle measuring instrument. The angle measuring scale has the disadvantages of low precision and large error; the laser angle measuring instrument has high precision but has the problem of complex system; and neither of them is suitable for detecting the change of the terahertz wave incidence angle. The disadvantages of the prior art are that in the terahertz wave band, many angle sensors of the prior art have the characteristics of low quality factor and low sensitivity due to the large frequency shift caused by the terahertz wave incidence angle, and it is difficult to maintain a good linear relationship. SUMMARY

[0005] The purpose of the present application is to provide a terahertz angle sensor based on a surface spring type structure of metamaterial, which solves the problem of large frequency shift caused by the terahertz wave incidence angle, improves the quality factor and sensitivity of the terahertz angle sensor, and can maintain a good linear relationship.

[0006] The above technical purpose of the present application is achieved by the following technical scheme:

[0007] The present application provides a terahertz angle sensor based on a surface spring type structure of metamaterial, comprising: a substrate; and a unit structure composed of a first structure and two oppositely placed second structures arranged on the surface of the substrate in a spring type structure; wherein the first structure is arranged on the surface of the substrate, and the two oppositely placed second structures are located in the first structure and perpendicular to each other.

[0008] In one implementation, the first structure is a square structure.

[0009] In one implementation, the second structure is an L-shaped structure.

[0010] In one implementation, the material of the first structure and the second structure is gold.

[0011] In an implementation manner, the thickness of the first structure and the second structure is 0.05 microns.

[0012] In an implementation manner, the thickness of the frame of the first structure and the second structure is 10 microns.

[0013] In an implementation manner, the length of the frame of the first structure is greater than the length of the frame of the second structure.

[0014] In an implementation manner, the length of the frame of the first structure is 130 microns.

[0015] In an implementation manner, the length of the frame of the second structure is 60 microns.

[0016] In an implementation manner, the material of the medium layer of the substrate surface is a polyimide film.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] The present application provides a terahertz angle sensor based on a metamaterial surface spring type structure, comprising: a substrate; and a unit structure composed of a first structure and two reversely placed second structures arranged on the surface of the substrate; wherein the first structure is arranged on the surface of the substrate, and the two reversely placed second structures are arranged in the area of the first structure and on the surface of the substrate. Therefore, the terahertz angle sensor based on the metamaterial surface spring type structure has the advantages of good quality factor, high sensitivity and high linearity. BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation of the embodiments of the present application. In the drawings:

[0020] Figure 1 The structure of the terahertz angle sensor based on the metamaterial surface spring type structure provided by the embodiments of the present application is shown;

[0021] Figure 2 The transmission curve S corresponding to the terahertz wave incident angle of 60° provided by the embodiments of the present application is shown 21 ;

[0022] Figure 3 The electric field distribution and the current distribution corresponding to the resonant frequency f=0.3588THz provided by the embodiments of the present application are shown;

[0023] Figure 4 The transmission curve S of the terahertz wave under different incident angles provided by the embodiments of the present application is shown 21 ;

[0024] Figure 5 The frequency deviation amount of the peak frequency of the transmission curve and the incidence angle relationship and the linear regression curve thereof provided by the embodiment of the application are shown.

[0025] Markings in the drawings and corresponding names of parts:

[0026] 1, first structure; 2, second structure. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with embodiments and drawings, the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and not as a limitation to the present application.

[0028] It should be noted that the term "include" or "may include" used in various embodiments of the present application indicates the existence of the claimed function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their synonyms only mean to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing, and should not be understood as first excluding the existence or addition of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing.

[0029] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation to the present application.

[0030] In addition, terms such as "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features.

[0031] First, the concepts involved in the present application are explained.

[0032] Terahertz wave: refers to the frequency between electronics and photonics;

[0033] Metamaterial: is a kind of electromagnetic material composed of artificial designed subwavelength microstructure units arranged in a certain periodic manner, which has special electromagnetic properties. Metamaterial is very sensitive to the dielectric constant of its structural surface environment or covering. When the surface environment or covering changes, the local electromagnetic field of the metamaterial structure is enhanced, and the resonance peak frequency position and amplitude of the structure change, which helps to improve the detection sensitivity of the terahertz sensor.

[0034] Metasurface: electromagnetic metasurface is a kind of composite material with subwavelength structure arranged artificially, and its electromagnetic properties can be designed arbitrarily by changing its geometric parameters.

[0035] Terahertz angle sensor: by changing the incident angle of terahertz wave, the electromagnetic response of metamaterial surface structure to terahertz wave changes, frequency deviation phenomenon occurs, and finally the linear relationship between frequency deviation and incident angle is established, realizing angle sensing.

[0036] Quality factor Q: reflects the resonance characteristics of the sensor. The larger the Q value, the sharper the characteristic spectrum curve, and the higher the sensitivity of the sensor. The expression of Q is: In the formula: f represents the resonance frequency; FWHM represents the full width at half maximum of the resonance peak.

[0037] Angle sensitivity S: defined as the offset amount of resonance frequency corresponding to one degree change of incident angle of terahertz wave, unit: THz / Degree. Its expression is: S=Δf / Δtheta(2), in the formula: Δf represents the frequency shift of the resonance peak position; Δtheta represents the change amount of the incident terahertz wave angle.

[0038] Please refer to Figure 1 , Figure 1 The structure of the terahertz angle sensor based on the surface spring type structure of the metamaterial provided by the embodiment of the application is shown in the figure, such as Figure 1As shown in the figure, the unit structure composed of the spring-type structure of the first structure 1 and two reversely placed second structures 2 comprises: a substrate; and a unit structure of a spring-type structure composed of the first structure 1 and two reversely placed second structures 2 arranged on the surface of the substrate; wherein the first structure 1 is arranged on the surface of the substrate, and the two reversely placed second structures 2 are located in the first structure 1 and perpendicular to each other. Optionally, the first structure 1 is a square structure. Optionally, the second structure 2 is an L-shaped structure. Optionally, the material of the first structure 1 and the second structure 2 is gold. Optionally, the thickness of the first structure 1 and the second structure 2 is 0.05 microns. Optionally, the thickness of the frame of the first structure 1 and the second structure 2 is 10 microns. Optionally, the frame length of the first structure 1 is greater than the frame length of the second structure 2. Optionally, the frame length of the first structure 1 is 130 microns. Optionally, the frame length of the second structure 2 is 60 microns. Optionally, the material of the medium layer on the surface of the substrate is a polyimide film.

[0039] In the embodiments of the present disclosure, as shown in the figure, Figure 1 The definitions of different physical quantities of the first structure 1 and the second structure 2 are as follows: the frame length of the first structure 1 is X1, the frame length of the second structure 2 is X2, and the width of the first structure 1 and the second structure 2 is W1. The size of the medium layer is 400 μm × 400 μm, and the thickness is 50 μm. It should be noted that the two segments of the L-shaped structure are equal in length. And as shown in the figure, Figure 1 The two reversely placed second structures 2 are

[0040] It should be noted that, Figure 1 The unit structure composed of the spring-type structure of the first structure 1 and two reversely placed second structures 2 can be periodically arranged and distributed on the surface of the substrate.

[0041] It can be understood that, in the Figure 1 The central axis of the spring-type structure composed of two reversely and perpendicularly placed second structures 2 is the diagonal line between the upper left corner and the lower right corner of the first structure 1; it can also be the diagonal line between the lower left corner and the upper right corner. Since the frame length X2 of the second structure 2 is smaller than the frame length X1 of the first structure 1, the frame length X2 of the second structure 2 can be adjusted accordingly under the condition of being smaller than X1, but since the second structure 2 is an L-shaped structure and the two segments are equal in length, the spring-type structure composed of two reversely and perpendicularly placed second structures 2 is an axisymmetric structure.

[0042] The working principle of the terahertz angle sensor provided in this embodiment is as follows: The first structure 1 formed on the substrate surface generates a resonance peak in the low-frequency band, and undergoes a near-linear frequency shift as the incident angle of the terahertz wave changes. However, the quality factor of the resonance peak and its sensitivity to the incident angle of the terahertz wave are not ideal. Therefore, this embodiment adds a second structure 2 to the first structure 1. The second structure 2 can interact with the first structure 1, improving the quality factor of the resonance peak and its sensitivity to the incident angle of the terahertz wave without changing the linear frequency shift phenomenon of the low-frequency resonance peak or generating redundant resonance peaks in the low-frequency band.

[0043] from Figure 2 Simulation results show that at the resonant frequency f = 0.3588 THz, the transmission curve S 21 There is a transmission trough, and the transmission coefficient at this time is S. 21 =0.09.

[0044] exist Figure 3 By observing the electric field and current distribution diagrams, it can be found that when the frequency of the observed terahertz wave is its resonant frequency, the electric field energy can be distributed along the longitudinal side of the spring-shaped structure formed by the upper and lower borders of the first structure 1 and the two opposing second structures 2. The current on the substrate surface flows in the same direction along the left and right borders of the first structure 1, while the current in the spring-shaped structure formed by the two opposing second structures 2 mainly flows longitudinally. The longitudinal side of the spring-shaped structure and the left and right borders of the first structure 1 can be considered as inductance L, and the lateral side of the spring-shaped structure and the upper and lower borders of the first structure 1 constitute capacitance C. According to the equivalent circuit principle, the electric field is generated because the induced charge generated by the incident wave accumulates at capacitance C, and the current is generated by the movement of charge; this is a typical LC resonance. The resonance of the entire structure can be equivalent to the superposition effect of LC resonances, and the resonant frequency can be approximated as: In the formula, the equivalent inductance is related to the geometry of the structure, and once the parameters are determined, the equivalent inductance generally does not change. When the incident angle of the terahertz wave is changed, the equivalent capacitance C will change, thus causing a frequency shift in the transmitted wave trough.

[0045] exist Figure 4 middle, Figure 4 Analyze the effect of changing the incident angle theta of the terahertz wave on the transmission coefficient S. 21 The effect of the incident angle changing from 30° to 60° is that the transmission trough gradually decreases, and the transmission coefficient S... 21 The change from 0.11 to 0.08 is only 0.03, which is relatively small. The resonant frequency corresponding to the transmission coefficient shifts to the left, and the frequency shift interval is basically the same when the incident angle is varied by a fixed angle change / Δtheta. This indicates that the frequency offset is approximately linearly related to the incident angle.

[0046] In Figure 5 In, Figure 5 Linear regression curve fitting is performed on the frequency deviation and the incident angle. The correlation coefficient of the fitted linear curve is 0.99, which indicates that there is a strong linear relationship between the frequency deviation and the incident angle. Using the quality factor calculation formula Q = f / FWHM (f is the resonance frequency, and FWHM is the full width at half maximum of the resonance peak) and the sensitivity calculation formula S = Δf / Δtheta (Δf is the frequency deviation, and Δtheta is the corresponding angle change) of the angle sensor, the quality factor Q = 106.8 is obtained, which indicates that the sensor has good resonance characteristics and low energy loss. The sensitivity of the angle sensor is S = 23.0 GHz / degree, which indicates that when the angle changes by 1°, the peak frequency will produce a frequency shift of 23 GHz.

[0047] In summary, all the indicators show that the terahertz angle sensor based on the metamaterial surface spring type structure provided by the embodiment of the application is a good terahertz sensor.

[0048] The above specific embodiments further illustrate the purpose, technical solutions and advantages of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A terahertz angle sensor based on a metamaterial surface spring structure, characterized in that, include: Base; And a unit structure consisting of a first structure and two opposing second structures arranged on the substrate surface; wherein, the first structure is arranged on the substrate surface, the two opposing second structures are located inside the first structure, and the two opposing second structures are perpendicular to each other; wherein, the central axis of the spring-type structure formed by the two opposing and mutually perpendicular second structures is the diagonal between the upper left corner and the lower right corner of the first structure or the diagonal between the lower left corner and the upper right corner of the first structure; when the frequency of the observed terahertz wave is the resonant frequency of the terahertz angle sensor, the electric field energy is distributed in the upper and lower borders of the first structure and the two opposing second structures to form the longitudinal side length of the spring-type structure.

2. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 1, characterized in that, The first structure is a square structure.

3. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 2, characterized in that, The second structure is an L-shaped structure.

4. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 3, characterized in that, The first and second structures are made of gold.

5. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 3, characterized in that, The thickness of both the first and second structures is 0.05 micrometers.

6. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 3, characterized in that, The thickness of the borders of both the first and second structures is 10 micrometers.

7. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 3, characterized in that, The border length of the first structure is greater than the border length of the second structure.

8. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 7, characterized in that, The border length of the first structure is 130 micrometers.

9. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 7, characterized in that, The border length of the second structure is 60 micrometers.

10. The terahertz angle sensor based on a metamaterial surface spring structure according to claim 1, characterized in that, The dielectric layer on the substrate surface is made of polyimide film.

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