Broadband enhanced fingerprint spectroscopy sensor, terahertz microstructure broadband enhanced fingerprint spectroscopy detection device and method

Abstract

This application provides a broadband enhanced fingerprint spectral sensor, a terahertz microstructure broadband enhanced fingerprint spectral detection device, and a method. The broadband enhanced fingerprint spectral sensor includes a substrate and a metal metasurface periodically attached to the front surface of the substrate. The metal metasurface includes multiple unit structures arranged along a first direction, each unit structure having a different period. Each unit structure includes multiple metasurface microstructures, with the major axis of each microstructure along a second direction and the minor axis along the first direction, which is perpendicular to the second direction. This application enables broadband enhanced fingerprint spectral detection in the THz band.

Description

Technical Field

[0001] This application relates to the field of terahertz technology, and in particular to a broadband enhanced fingerprint spectrum sensor, a terahertz microstructure broadband enhanced fingerprint spectrum detection device and method. Background Technology

[0002] Terahertz (THz, 1THz = 10 12 THz (THz) waves refer to the electromagnetic spectrum between microwaves and infrared light waves, with a frequency range typically defined as 0.1–10 THz. Due to their superior properties such as low photon energy, non-invasiveness, non-ionization, spectral fingerprint specificity, and wide bandwidth, they have attracted widespread attention in sensing and detection, with applications spanning national defense, healthcare, and biochemical analysis. As a core device in sensing and detection, THz sensors have consistently received considerable research attention. Artificial metasurfaces are artificially fabricated subwavelength periodic microstructures that strongly interact with electromagnetic fields. Through structural design, they can exhibit strong resonant characteristics in the THz spectrum, significantly improving detection sensitivity. Traditional THz sensing generally falls under optical refractive index sensing, which reflects changes in the refractive index of a sample by the frequency shift of the resonant peak position of a microstructure sensor. This method can achieve high-precision sensing of refractive index changes in a sample, enabling the detection of properties such as water content (International Journal of Agricultural and Biological Engineering, 11, 178 (2018)), solution concentration (Sensors and Actuators B: Chemical, 330, 129315 (2021)), and film thickness (Applied Physics Letters, 115, 151105 (2019)). However, because the sensor resonant position is a single frequency point, it can only achieve single-frequency detection of the sample, reflecting the macroscopic properties of the sample, and cannot achieve THz broadband fingerprint spectroscopy detection of the sample.

[0003] The interaction between THz waves and matter is highly complex. The characteristic lifetimes (on the order of picoseconds) and energy ranges (on the order of meVs) of many matter's energy level transition systems match the typical pulse width and photon energy of THz pulses. This results in many collective vibrational-rotational modes, such as skeletal vibrations and configurational bending, associated with the molecular configuration and its changes, residing in the THz band. The THz spectra of these substances possess strong fingerprint specificity, directly reflecting molecular configuration information. This is highly advantageous for detecting various types of sensor samples, especially biochemical samples with complex molecular structures. However, the characteristic spectra (such as absorption and rotation spectra) of most sensor samples in the THz band are very weak, making direct detection difficult. Currently, broadband enhanced fingerprint spectroscopy detection in the THz band remains a challenge due to the lack of corresponding broadband detection sensors and technologies. The main difficulty stems from the contradiction between the narrow-band high-Q characteristics required for high-sensitivity sensing and broadband fingerprint spectroscopy detection.

[0004] Currently, some studies have explored altering the geometric parameters of metasurface microstructure sensors (Science, 360, 1105 (2018)) or the incident light angle (Science Advances, 5, eaaw2871 (2019)) to change the sensor's resonant frequency position, thereby enabling the detection of characteristic spectra at various frequency points. Broadband enhanced fingerprint spectroscopy detection is then achieved by taking the envelope of a series of characteristic spectra. This method can achieve broadband characteristic absorption spectroscopy detection while maintaining the sensor's strong resonance, high Q value, and high sensing sensitivity. However, related research has been applied to enhanced sensing of infrared absorption spectroscopy, and there are few reports on related research in the THz band.

[0005] In summary, on the one hand, the rapid development of THz technology and the urgent needs in fields such as biochemistry have placed higher performance demands on THz sensors; on the other hand, existing THz sensors can only achieve single-frequency sensing and cannot realize broadband enhanced fingerprint spectral detection. Therefore, the development of broadband enhanced fingerprint spectral sensors and their application methods have significant scientific research and application value. Summary of the Invention

[0006] The purpose of this application is to provide a broadband enhanced fingerprint spectrum sensor, a terahertz microstructure broadband enhanced fingerprint spectrum detection device and method, which can realize broadband enhanced fingerprint spectrum detection in the THz band.

[0007] One aspect of this application provides a broadband enhanced fingerprint sensor. The broadband enhanced fingerprint sensor includes a substrate and a metallic metasurface periodically attached to the front surface of the substrate. The metallic metasurface includes a plurality of unit structures arranged along a first direction, the plurality of unit structures having different periods, each unit structure including a plurality of metasurface microstructures, the major axis of each metasurface microstructure being along a second direction, and the minor axis being along the first direction, the first direction being perpendicular to the second direction.

[0008] Furthermore, the period of the plurality of unit structures gradually changes along the first direction.

[0009] Furthermore, the size range of the period of the plurality of unit structures along the first direction is 100μm to 350μm.

[0010] Furthermore, the metal metasurface includes an elliptical metal metasurface or a rectangular metal metasurface.

[0011] Furthermore, the dimensions of the major and minor axes of the metasurface microstructures in each of the unit structures are related to the period of the unit structure.

[0012] Furthermore, the ratio of the major axis to the minor axis of each of the metasurface microstructures is 4 to 6.

[0013] Furthermore, the major axis of the metasurface microstructure in each unit structure is 0.8 to 0.9 times the period of the unit structure, and the minor axis is 0.15 to 0.2 times the period of the unit structure.

[0014] Furthermore, the arrangement and orientation of the metasurface microstructures in each of the unit structures are consistent.

[0015] Furthermore, each of the unit structures has a length along the first direction and a width along the second direction, with the length of each unit structure being 3-5 mm and the width being 10-15 mm.

[0016] Furthermore, the metal metasurface is formed by etching a gold film with a thickness of 200 nm.

[0017] Furthermore, the substrate comprises a quartz glass substrate.

[0018] Furthermore, the thickness of the quartz glass substrate is 300~500μm, and the transmittance is above 90%.

[0019] Another aspect of this application provides a terahertz microstructure broadband enhanced fingerprint spectrum detection device. The detection device includes a terahertz wave emission source, a broadband enhanced fingerprint spectrum sensor as described above, and a displacement stage. The broadband enhanced fingerprint spectrum sensor is fixed on the displacement stage, the displacement stage is translatable along the first direction, and the terahertz wave emission source is used to emit terahertz waves to the metal metasurface of the broadband enhanced fingerprint spectrum sensor.

[0020] Another aspect of this application provides a method for detecting terahertz microstructure broadband enhanced fingerprint spectroscopy. The detection method uses the terahertz microstructure broadband enhanced fingerprint spectroscopy detection device described above for detection, and the detection method includes:

[0021] A sensing sample is added to the metal metasurface of the broadband enhanced fingerprint sensor, wherein the broadband enhanced fingerprint sensor is a reflective sensor.

[0022] A linearly polarized terahertz wave vibrating along the second direction is incident in a plane formed by the first and third directions along a direction at a certain angle to the normal of the metal metasurface. The terahertz wave resonates with the metal metasurface after the addition of the sensing sample. The third direction is perpendicular to the first and second directions.

[0023] The displacement stage is moved along the first direction to change the incident position of the terahertz wave, so that the terahertz wave interacts with the unit structure of different periods after the addition of the sensing sample to generate strong resonance.

[0024] The reflectance spectrum of the unit structure in each period is measured to obtain the reflectance spectrum of the sensing sample corresponding to the reflectance peak of the unit structure in different periods at different frequency positions; and

[0025] Broadband enhanced fingerprint spectrum detection of the sensor sample is achieved based on the reflection spectrum of the sensor sample at different frequency positions of the reflection peak.

[0026] Furthermore, the detection method also includes:

[0027] The original reflection spectra of the unit structures corresponding to different periods at different frequency positions were obtained in advance without the addition of the sensing sample; and

[0028] The original reflection spectra of the unit structures with different periods are normalized to obtain a sensing reference reflection spectrum with reflection peaks covering a certain frequency range.

[0029] The broadband enhanced fingerprint spectrum detection of the sensing sample based on the reflection spectrum of the reflection peak at different frequency positions includes:

[0030] The normalization parameter of the sensing reference reflection spectrum is used to normalize the reflection spectrum of the sensing sample at different frequency positions of the reflection peak, and the peak envelope is taken to realize the broadband enhanced fingerprint spectrum detection of the sensing sample.

[0031] The beneficial effects and advantages of this application are as follows:

[0032] 1. Metal metasurfaces are small, easy to integrate, simple in structure, and easy to process.

[0033] 2. Metal metasurface microstructures possess strong resonance and high Q values, which can significantly enhance the absorption of the sensing sample at the resonant frequency position. This is of great significance for enhancing the weak characteristic spectral signals of the sensing sample in the THz band and improving the detection sensitivity of the sensing sample.

[0034] This application utilizes a periodically varying broadband enhanced fingerprint spectral sensor structure. By changing the incident position of the THz wave, the reflection spectrum of each periodic metal metasurface unit structure is measured and the peak envelope is taken. This method enables broadband enhanced fingerprint spectral detection of the sample, which can directly reflect the configuration and conformation information of the molecule. It is of great significance for the sensing and detection of biochemical samples with complex molecular structures. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a broadband enhanced fingerprint spectrum sensor according to an embodiment of this application.

[0036] Figure 2 This is a schematic diagram of the unit structure of an elliptical and rectangular metal metasurface according to an embodiment of this application.

[0037] Figure 3 This is a diagram showing the relationship between the periodic dimensions and the resonant frequency positions of a unit structure of a metallic metasurface according to an embodiment of this application.

[0038] Figure 4 This application presents a normalized sensing reference reflectance spectrum and a sensing sample reflectance spectrum with unit structures having different periodic sizes, representing one embodiment of the present application.

[0039] Figure 5 This is an absorption fingerprint spectrum of a sensor sample according to an embodiment of this application.

[0040] Figure 6 This is a flowchart of a terahertz microstructure broadband enhanced fingerprint spectrum detection method according to an embodiment of this application. Detailed Implementation

[0041] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses consistent with some aspects of this application as detailed in the appended claims.

[0042] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. Unless otherwise defined, the technical or scientific terms used in the embodiments of this application should be understood in their ordinary meaning as understood by one of ordinary skill in the art to which this application pertains. The singular forms “a,” “the,” and “the” used in the specification and appended claims of this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0043] This application provides a broadband enhanced fingerprint spectroscopy sensor 10. This broadband enhanced fingerprint spectroscopy sensor 10 can achieve broadband enhanced fingerprint spectroscopy detection in the THz band, directly reflecting the configurational information of molecules, and is of great significance for sensing and detecting biochemical samples with complex molecular structures.

[0044] Figure 1 A schematic diagram of the structure of a broadband enhanced fingerprint spectrum sensor 10 according to an embodiment of this application is shown. Figure 1 As shown, a broadband enhanced fingerprint sensor 10 according to one embodiment of this application includes a substrate and a metal metasurface 12 periodically attached to the front surface of the substrate. In some embodiments, the substrate of this application may include, but is not limited to, a quartz glass substrate 11. The quartz glass substrate 11 has a thickness of 300~500μm and a transmittance of 90% or more.

[0045] The metallic metasurface 12 includes a plurality of unit structures 121 arranged along a first direction (e.g., the x-axis direction in the figure). The plurality of unit structures 121 have different periods T. Each unit structure 121 includes a plurality of metasurface microstructures 1210. The major axis A1 of each metasurface microstructure 1210 is along a second direction (e.g., the y-axis direction in the figure), and the minor axis A2 is along the first direction (x-axis direction), wherein the first direction is perpendicular to the second direction.

[0046] In some embodiments, the metal metasurface 12 of this application may be etched onto a gold film with a thickness of 200 nm. The metal metasurface 12 in the embodiments of this application may include an elliptical metal metasurface or a rectangular metal metasurface. Figure 2This application discloses a schematic diagram of the unit structure 121 of an elliptical and rectangular metallic metasurface 12 according to an embodiment of the present application, wherein, Figure 2 (a) shows a schematic diagram of the unit structure 121 of the elliptical metallic metasurface 12, and (b) shows a schematic diagram of the unit structure 121 of the rectangular metallic metasurface 12. Figure 2 As shown, the dimensions of the major axis A1 and minor axis A2 of the metasurface microstructure 1210 in each unit structure 121 are both related to the period T of the unit structure 121. In some embodiments, the ratio of the major axis A1 to the minor axis A2 of each metasurface microstructure 1210 is 4 to 6. In one embodiment, the major axis A1 of each metasurface microstructure 1210 in each unit structure 121 is 0.8 to 0.9 times the period T of the unit structure 121, i.e., A1 = 0.8T to 0.9T; the minor axis A2 is 0.15 to 0.2 times the period T of the unit structure 121, i.e., A2 = 0.15T to 0.2T.

[0047] The arrangement and orientation of the metasurface microstructures 1210 in each unit structure 121 are consistent.

[0048] In some embodiments, the period T of the plurality of unit structures 121 in this application gradually varies along a first direction (x-axis direction). In the embodiment illustrated in this application, the period T of the plurality of unit structures 121 gradually increases along the x-axis direction. Of course, in other embodiments, the period T of the plurality of unit structures 121 in this application gradually decreases along the x-axis direction. The magnitude of the gradual change in the period T of the unit structures 121 in the broadband enhanced fingerprint spectrum sensor 10 of this application can be determined according to actual conditions. The denser the interval of the period T of the unit structures 121, the higher the accuracy of the measurement result.

[0049] In some embodiments, the size range of the period T of the plurality of unit structures 121 along the first direction (x-axis direction) is 100 μm to 350 μm. In the embodiment illustrated in this application, the first unit structure 121 has a period of T1, the second unit structure 121 has a period of T2, the third unit structure 121 has a period of T3, ..., and so on, with the nth unit structure 121 having a period of T. n The period of unit structure 121 along the x-axis ranges from T1 (100 μm) to T n (350μm) change.

[0050] Each unit structure 121 has a length l along a first direction (x-axis direction) and a width w along a second direction (y-axis direction). The length l of each unit structure 121 is 3~5mm and the width w is 10~15mm.

[0051] This application also provides a terahertz microstructure broadband enhanced fingerprint spectrum detection device 1. The terahertz microstructure broadband enhanced fingerprint spectrum detection device 1 includes a terahertz wave emitting source (not shown), a broadband enhanced fingerprint spectrum sensor 10 as described above, and a displacement stage 20. The terahertz wave emitting source can be used to emit terahertz waves onto the metal metasurface 12 of the broadband enhanced fingerprint spectrum sensor 10. The broadband enhanced fingerprint spectrum sensor 10 is fixed on the displacement stage 20, which can translate along a first direction (x-axis direction). Therefore, the displacement stage 20 can drive the broadband enhanced fingerprint spectrum sensor 10 to translate along the x-axis direction.

[0052] In some embodiments, the broadband enhanced fingerprint spectrum sensor 10 of this application is a reflective sensor. The basic working principle of the broadband enhanced fingerprint spectrum sensor 10 and the terahertz microstructure broadband enhanced fingerprint spectrum detection device 1 of this application is as follows: A linearly polarized terahertz wave vibrating along the Y-axis is incident in the xz plane at an angle of 5° to the normal of the metal metasurface 12. The terahertz wave interacts with the microstructure of the metal metasurface 12, generating strong resonance and forming a reflection peak in the reflection spectrum. Since the microstructure of the metal metasurface 12 is symmetrical with respect to both the incident direction and polarization direction of the electromagnetic wave, the polarization direction of the reflected wave does not change; only the reflected signal in the Y-axis direction needs to be detected. Therefore, the calculation method for the reflection spectrum is as follows:

[0053] (1)

[0054] in, and These represent the amplitudes of the incident wave and the reflected wave in the y-axis direction, respectively.

[0055] Due to the resonance effect of the microstructure of the metallic metasurface 12, a reflection peak will form at a specific frequency position in the reflection spectrum. The method for calculating the Q value of the reflection peak is as follows:

[0056] (2)

[0057] in, The peak frequency of the reflection is denoted by FWHM, which represents the full width at half maximum (FWHM) of the reflection peak.

[0058] The Q-value of the broadband enhanced fingerprint sensor 10 does not change with normalization calculations. When a sensing sample that absorbs THz waves is added to the surface of the broadband enhanced fingerprint sensor 10, the reflection peaks are weakened, and the absorption intensity of the sensing sample is significantly enhanced due to the resonant field generated by the microstructure of the metal metasurface 12. For the unit cell structure 121 of the metal metasurface 12 with different periods T, the reflection peaks are located at different frequency positions. Figure 3A diagram showing the relationship between the periodic dimensions of the unit cell structure 121 of a metallic metasurface 12 according to an embodiment of this application and the position of the resonant frequency is presented. Figure 3 As shown in the figure, the color depth represents the reflection intensity at different period sizes and frequency positions, and the dots represent the frequency positions of the reflection peaks at different period sizes.

[0059] In the sensing and detection process, the sensor is moved along the x-axis by the displacement stage 20, thereby changing the incident position of the THz wave. This allows the THz wave to interact with the unit structure 121 of the metal metasurface 12 with different periods T, generating resonance, such as... Figure 1 As shown. Based on the relationship between the periodic size of the unit structure 121 of the metal metasurface 12 and the resonant frequency position, it can be seen that the peak positions of the reflection spectra of the unit structure 121 of the metal metasurface 12 with different periods T gradually change. Therefore, a series of reflection spectra corresponding to period T can be measured. Normalizing this series of reflection spectra yields spectral lines whose reflection peaks cover a certain frequency range. This series of spectral lines is the sensing reference reflection spectrum, and the normalization parameter is the normalization parameter of this sensing reference reflection spectrum.

[0060] When a sensing sample is added to the surface of the broadband enhanced fingerprint spectrum sensor 10, the THz wave interacts with the unit structure 121 of the metal metasurface 12 with different periods T by moving the displacement stage 20, resulting in a series of sensing sample reflection spectra corresponding to period T. The sensing sample reflection spectrum is normalized using the normalization parameter of the sensing reference reflection spectrum and the peak envelope is taken. Thus, broadband enhanced fingerprint spectrum detection of the sensing sample can be realized. Based on the detection of macroscopic properties such as sensing sample concentration and refractive index change, it can reflect the microscopic configuration and conformation information of the sensing sample molecules.

[0061] The broadband enhanced fingerprint sensor 10 of this application will be further described below through a specific embodiment. It is understood that the specific embodiment described herein is for illustrative purposes only and does not constitute a limitation thereof. In this specific embodiment, the structural parameters of the broadband enhanced fingerprint sensor 10 are as follows: the thickness of the quartz glass substrate 11 is 500 μm; an elliptical metallic metasurface 12 is selected; the structural material is gold; and the periodic variation of the unit structure 121 along the x-axis is T1 (100 μm) ~ T... nThe microstructure 121 of the elliptical metasurface 121 has a length of 3 mm (350 μm), a periodic variation interval of 10 μm, and a total of 26 periods. Each period's unit structure 121 has a length of 3 mm (larger than the focused spot of a THz wave) and a width of 10 mm. Therefore, the total length of the broadband enhanced fingerprint spectrum sensor 10 in the x-axis direction is 7.8 cm, and the width in the y-axis direction is 1 cm. The major axis A1 of the elliptical metasurface microstructure 1210 is 0.8 T along the y-axis direction, and the minor axis A2 is 0.16 T along the x-axis direction. The aspect ratio of the unit structure 121 of the metallic metasurface 12 is 5. The arrangement and orientation of the unit structures 121 in all periods are consistent.

[0062] Figure 3 This illustrates the relationship between the periodic dimensions of the unit cell structure 121 of the metallic metasurface 12 and the resonant frequency position in this specific embodiment. Figure 3 It can be seen that as the periodic size of the unit structure 121 of the metallic metasurface 12 increases, its resonant frequency shifts towards lower frequencies, and the trend is nonlinear. As the periodic size of the unit structure 121 gradually increases, the change in the resonant frequency position becomes smaller and smaller. When the periodic size is above 350 μm, the resonant frequency no longer changes significantly. Therefore, in this specific implementation scheme, the maximum value of the period T variation is chosen to be 350 μm.

[0063] Figure 4 This paper discloses a schematic diagram of the normalized sensing reference reflectance spectrum and the sensing sample reflectance spectrum of a unit structure 121 with different periodic sizes according to an embodiment of this application. (a) shows the normalized sensing reference reflectance spectrum of the unit structure 121 with different periodic sizes; (b) shows the sensing sample reflectance spectrum obtained according to the normalized parameters corresponding to the sensing reference reflectance spectrum in (a) after a sensing sample is added to the surface of the broadband enhanced fingerprint sensor 10. Figure 4 As can be seen in (a), as the period size of the unit structure 121 decreases, the full width at half maximum (FWHM) of the reflection spectrum resonance peak gradually increases, leading to a gradual decrease in the 10Q value of the broadband enhanced fingerprint sensor 121. The unit structure 121 of the metal metasurface 12 with a period less than 100 μm is no longer suitable for sensing enhancement. Therefore, considering the above limitations, this application selects a period size in the range of 100~350 μm, corresponding to resonant frequencies of 1.0 THz and 0.35 THz, respectively, achieving broadband coverage in the range of approximately 0.65 THz.

[0064] Subsequently, a sensing sample was added to the surface of the broadband enhanced fingerprint sensor 10. The sensor 10 was then moved along the x-axis by a displacement stage 20, causing the THz wave to interact with the unit structures 121 of the metal metasurface 12 with different periods T. This yielded a series of reflection peaks corresponding to period T at different frequency positions, representing the reflection spectra of the sensing sample. The normalized parameters of the reference reflection spectrum without the added sample were used to normalize the reflection spectrum of the sensing sample after the addition of the sample. The results are as follows: Figure 4 As shown in (b). Compare Figure 4 As can be seen from (a) and (b), due to the fingerprint absorption spectrum of the sample, the absorption intensity varies at different frequency positions, resulting in different peak values ​​of the reflection spectrum corresponding to the unit structure 121 of the metal metasurface 12 of each period size. By taking the peak envelope of the reflection spectrum of the series of samples, the broadband enhanced fingerprint spectrum of the sample can be obtained.

[0065] Figure 5 An absorption fingerprint spectrum of a sensor sample according to an embodiment of this application is disclosed. Figure 5 The dashed line in the figure represents the broadband absorption fingerprint spectrum obtained by directly detecting a 200μm thick sensor sample without using the broadband enhanced fingerprint spectrum sensor 10 of this application. It can be seen that the absorption spectrum intensity is very weak, with a maximum absorption of only 0.17. Figure 5 The solid dotted line in the diagram represents the peak envelope of the reflectance spectrum detected using the broadband enhanced fingerprint sensor 10 of this application on a 200 μm thick sample; this is the broadband absorption enhanced fingerprint spectrum of the sample. It can be seen that within the spectral range of 0.35–1.0 THz, the strongest absorption of the sample increases to 0.89, representing an enhancement of approximately 5.3 times compared to the case without the broadband enhanced fingerprint sensor 10.

[0066] Therefore, by using the broadband enhanced fingerprint spectrum sensor 10 and sensing method of the present application embodiment, broadband enhanced fingerprint spectrum detection of the sensing sample can be realized, and it has a good resonance enhancement effect. It can be applied to the sensing and detection of complex molecular structure configuration information, and has important application value in the field of biochemical sensing.

[0067] This application also provides a method for detecting terahertz microstructure broadband enhanced fingerprint spectrum. This detection method uses the terahertz microstructure broadband enhanced fingerprint spectrum detection device 1 described above, wherein the broadband enhanced fingerprint spectrum sensor 10 is a reflective sensor. Figure 6 A flowchart illustrating a terahertz microstructure broadband enhanced fingerprint spectrum detection method according to an embodiment of this application is disclosed. Figure 6 As shown, a terahertz microstructure broadband enhanced fingerprint spectrum detection method according to an embodiment of this application may include steps S11 to S15.

[0068] In step S11, a sensing sample is added to the metal metasurface 12 of the broadband enhanced fingerprint sensor 10.

[0069] In step S12, the linearly polarized terahertz wave vibrating along the second direction of the electric field is directed in the first direction ( Figure 1 (x-axis direction) and third direction ( Figure 1 The terahertz wave is incident on the plane (i.e., the xz plane) formed by the z-axis direction and the normal of the metal metasurface 12 at a certain angle (e.g., 5 degrees). The terahertz wave resonates with the metal metasurface 12 after the addition of the sensing sample. The third direction (z-axis direction) is perpendicular to the first direction (x-axis direction) and the second direction (y-axis direction).

[0070] In step S13, along the first direction ( Figure 1 The displacement stage 20 is moved along the x-axis to change the incident position of the terahertz wave, so that the terahertz wave interacts with the unit structure 121 of different periods T after the addition of the sensing sample to generate strong resonance.

[0071] In step S14, the reflection spectrum of the unit structure 121 for each period T in step S13 is measured to obtain the reflection spectrum of the sensing sample at different frequency positions of the reflection peak of the unit structure 121 corresponding to different periods T.

[0072] In step S15, broadband enhanced fingerprint spectrum detection of the sensing sample is achieved based on the reflection spectrum of the sensing sample at different frequency positions obtained in step S14.

[0073] In some embodiments, the terahertz microstructure broadband enhanced fingerprint spectrum detection method of this application may further include steps S21 and S22.

[0074] In step S21, the original reflection spectra of the reflection peaks of the unit structure 121 corresponding to different periods T at different frequency positions can be obtained in advance when no sensing sample is added.

[0075] In step S22, the original reflection spectra of the unit structure 121 with different periods T obtained in step S21 are normalized to obtain a sensing reference reflection spectrum with reflection peaks covering a certain frequency range.

[0076] Specifically, step S15, which involves detecting the broadband enhanced fingerprint spectrum of the sensing sample based on the reflection spectrum of the reflection peak at different frequency positions, may include: using the normalization parameter of the sensing reference reflection spectrum obtained in step S22 to normalize the reflection spectrum of the sensing sample at different frequency positions obtained in step S14 and taking the peak envelope to achieve broadband enhanced fingerprint spectrum detection of the sensing sample.

[0077] The beneficial effects and advantages of this application are as follows:

[0078] 1. The microstructure of the metal metasurface 12 adopts an elliptical / rectangular design, is made of gold, and features reflective sensing. It is small, easy to integrate, simple in structure, and easy to process.

[0079] 2. Elliptical / rectangular metallic metasurfaces with 12 microstructures possess strong resonance and high Q values, which can significantly enhance the absorption of the sensing sample at the resonant frequency position. This is of great significance for enhancing the weak characteristic spectral signals of the sensing sample in the THz band and improving the detection sensitivity of the sensing sample.

[0080] This application utilizes a periodically varying broadband enhanced fingerprint spectral sensor 10 structure. By changing the incident position of the THz wave, the reflection spectrum of the unit structure 121 of each periodic metal metasurface 12 is measured and the peak envelope is taken. This method enables broadband enhanced fingerprint spectral detection of the sample, which can directly reflect the configuration and conformation information of the molecule. It is of great significance for the sensing and detection of biochemical samples with complex molecular structures.

[0081] The broadband enhanced fingerprint spectrum sensor, terahertz microstructure broadband enhanced fingerprint spectrum detection device, and method provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the broadband enhanced fingerprint spectrum sensor, terahertz microstructure broadband enhanced fingerprint spectrum detection device, and method in the embodiments of this application. The descriptions of the embodiments above are only for helping to understand the core ideas of this application and are not intended to limit this application. It should be noted that for those skilled in the art, several improvements and modifications can be made to this application without departing from the spirit and principles of this application, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A broadband enhanced fingerprint spectrum sensor, characterized in that: include: Substrate; as well as A metallic metasurface is attached to the front surface of the substrate. The metallic metasurface includes multiple unit structures arranged along a first direction. The multiple unit structures have different periods. Each unit structure includes multiple metasurface microstructures. The major axis of each metasurface microstructure is along a second direction, and the minor axis is along the first direction. The first direction is perpendicular to the second direction. The period of the multiple unit structures gradually changes along the first direction. The dimensions of the major and minor axes of the metasurface microstructures in each unit structure are related to the period of the unit structure. The arrangement and orientation of the metasurface microstructures in each unit structure are consistent.

2. The broadband enhanced fingerprint sensor as described in claim 1, characterized in that: The size range of the period of the plurality of unit structures along the first direction is 100μm to 350μm.

3. The broadband enhanced fingerprint sensor as described in claim 1, characterized in that: The metal metasurface includes an elliptical metal metasurface or a rectangular metal metasurface.

4. The broadband enhanced fingerprint sensor as described in claim 1, characterized in that: The ratio of the major axis to the minor axis of each of the metasurface microstructures is 4 to 6.

5. The broadband enhanced fingerprint sensor as described in claim 1, characterized in that: The major axis of each metasurface microstructure in the unit structure is 0.8 to 0.9 times the period of the unit structure, and the minor axis is 0.15 to 0.2 times the period of the unit structure.

6. The broadband enhanced fingerprint sensor as described in claim 1, characterized in that: Each of the unit structures has a length along the first direction and a width along the second direction, with the length of each unit structure being 3-5 mm and the width being 10-15 mm.

7. The broadband enhanced fingerprint sensor as described in claim 1, characterized in that: The metallic metasurface is formed by etching a gold film with a thickness of 200 nm.

8. The broadband enhanced fingerprint sensor as described in claim 1, characterized in that: The substrate includes a quartz glass substrate.

9. The broadband enhanced fingerprint spectrum sensor as described in claim 8, characterized in that: The thickness of the quartz glass substrate is 300~500μm, and the transmittance is above 90%.

10. A terahertz microstructure broadband enhanced fingerprint spectrum detection device, characterized in that: The device includes a terahertz wave emission source, a broadband enhanced fingerprint spectrum sensor as described in any one of claims 1-9, and a displacement stage. The broadband enhanced fingerprint spectrum sensor is fixed on the displacement stage, and the displacement stage is translatable along the first direction. The terahertz wave emission source is used to emit terahertz waves to the metal metasurface of the broadband enhanced fingerprint spectrum sensor.

11. A method for detecting broadband enhanced fingerprint spectra of terahertz microstructures, characterized in that, The detection is performed using the terahertz microstructure broadband enhanced fingerprint spectroscopy detection device as described in claim 10, and the detection method includes: A sensing sample is added to the metal metasurface of the broadband enhanced fingerprint sensor, wherein the broadband enhanced fingerprint sensor is a reflective sensor. A linearly polarized terahertz wave vibrating along the second direction is incident in a plane formed by the first and third directions along a direction at a certain angle to the normal of the metal metasurface. The terahertz wave resonates with the metal metasurface after the addition of the sensing sample. The third direction is perpendicular to the first and second directions. The displacement stage is moved along the first direction to change the incident position of the terahertz wave, so that the terahertz wave interacts with the unit structure of different periods after the addition of the sensing sample to generate strong resonance. The reflectance spectrum of the unit structure in each period is measured to obtain the reflectance spectrum of the sensing sample corresponding to the reflectance peak of the unit structure in different periods at different frequency positions; and Broadband enhanced fingerprint spectrum detection of the sensor sample is achieved based on the reflection spectrum of the sensor sample at different frequency positions of the reflection peak.

12. The terahertz microstructure broadband enhanced fingerprint spectrum detection method as described in claim 11, characterized in that, Also includes: The original reflection spectra of the reflection peaks of the unit structures corresponding to different periods at different frequency positions were obtained in advance when the sensing sample was not added; and The original reflection spectra of the unit structures with different periods are normalized to obtain a sensing reference reflection spectrum with reflection peaks covering a certain frequency range. The broadband enhanced fingerprint spectrum detection of the sensing sample based on the reflection spectrum of the reflection peak at different frequency positions includes: The normalization parameter of the sensing reference reflection spectrum is used to normalize the reflection spectrum of the sensing sample at different frequency positions of the reflection peak, and the peak envelope is taken to realize the broadband enhanced fingerprint spectrum detection of the sensing sample.

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