A terahertz photothermal detector based on metasurface loading

Abstract

The present invention relates to a terahertz photothermal detector based on metasurface loading, belonging to the field of terahertz detectors. The device comprises a coupling module, a readout module, and a substrate module. The coupling module is used to absorb terahertz radiation and generate temperature changes. The readout module comprises a thermosensitive film, a circuit structure, a support cantilever, and contacts. The thermosensitive film is applied to the back of the coupling module and connected to the contacts via the circuit structure, and the resistance of the thermosensitive film is read via the contacts. The support cantilever is used to suspend the coupling module, part of the circuit structure, and the thermosensitive film, and is separated and thermally insulated from the substrate module. The present invention uses a metasurface absorbing structure as the coupling module of the terahertz detector, improving the detector coupling efficiency and responsiveness. The thermosensitive film is also utilized to achieve high-sensitivity real-time detection at room temperature, providing technical support for terahertz focal plane array imaging systems.

Description

Technical Field

[0001] The present invention belongs to the field of terahertz detectors, and in particular relates to a terahertz photothermal detector based on metasurface loading. Background Art

[0002] The terahertz (THz) band is typically defined as the 0.1-10 THz frequency range, lying between the microwave and optical infrared bands. Its corresponding wavelength is 3 mm to 30 μm, covering the millimeter to submillimeter wave bands. Unlike the microwave and optical infrared bands, the interaction between THz radiation and matter is primarily related to molecular rotation. This molecular rotational interaction begins in the microwave band, peaks in the frequency range from several hundred GHz to several THz, and then decays exponentially. Due to the unique penetrability and safety of THz waves, they have broad application prospects in security testing, biomedical testing, and other areas. Therefore, THz detectors have attracted the attention of researchers both domestically and internationally.

[0003] Terahertz technology spans the fields of microwave electronics and infrared photonics. It generally employs the same electronic research methods as microwave technology in the low-frequency band and the same photonic research methods as infrared technology in the high-frequency band. Currently, traditional electronics or photonics alone cannot fully meet the research and application needs of terahertz detectors and imaging systems. Compared with existing microwave and infrared technologies, terahertz-related technologies are still relatively immature, leading scientists to refer to this range of the electromagnetic spectrum as the terahertz gap. Several studies have been conducted on terahertz detectors, and common detectors can be categorized in principle as coherent and incoherent. Coherent detection preserves the amplitude and phase information of the signal, offering the advantage of high sensitivity. However, it requires a mixer and local oscillator (LO) signal, resulting in a complex structure and high cost. Incoherent detection technology, based on direct energy detection via thermal radiation absorption, is a broadband detection technique that does not require a local oscillator (LO) or mixer. It offers a simple, compact, and easily integrated system structure, and exhibits excellent response performance even at room temperature. It is not difficult to see that incoherent detectors are more suitable for the promotion and use of terahertz detection technology.

[0004] A bolometer is a typical incoherent detector that converts the energy in electromagnetic radiation into heat energy and reads it out through a thermosensitive structure to obtain the power of the radiation signal. Currently, terahertz bolometers typically use natural materials such as gallium nitride as a coupling structure, absorbing the energy in terahertz radiation and completing the conversion between light and heat energy. However, there is a lack of materials with high absorptivity in the terahertz band in nature. The absorptivity of absorbing films such as gallium nitride is generally below 40%, and it is difficult to selectively absorb specific frequencies. This, to a certain extent, limits the sensitivity of bolometers in the terahertz band. In addition, although some terahertz bolometers based on new semiconductor materials have been proposed, they must operate in an ultra-low temperature environment (80K), which requires additional refrigeration equipment, which brings inconvenience to performance stability and long-term equipment maintenance.

[0005] In summary, a terahertz detector that combines high sensitivity, room-temperature operation, and real-time imaging is essential for the development of terahertz detection technology. This invention combines a metasurface, an artificial electromagnetic structure, to improve the coupling efficiency of the terahertz detector. Furthermore, it employs a thermosensitive film to achieve high-sensitivity, real-time detection at room temperature. This invention can provide technical support for terahertz focal plane array imaging systems. Summary of the Invention

[0006] Technical issues to be solved:

[0007] In order to avoid the shortcomings of the existing technology, the present invention provides a terahertz photothermal detector based on metasurface loading. To address the problems of low coupling efficiency and low responsiveness of existing terahertz thermal detectors at room temperature, the present invention uses a metasurface absorbing structure as a coupling module of the terahertz detector to improve the detector coupling efficiency and responsiveness, and uses a thermosensitive film to achieve high-sensitivity real-time detection at room temperature, providing technical support for terahertz focal plane array imaging systems.

[0008] The technical solution of the present invention is: a terahertz photothermal detector based on metasurface loading, comprising a coupling module, a readout module and a substrate module, wherein the coupling module is used to absorb terahertz radiation and generate temperature changes;

[0009] The readout module includes a thermosensitive film, a circuit structure, a supporting cantilever, and contacts; the thermosensitive film is applied to the back of the coupling module and connected to the contacts through the circuit structure, and the resistance value of the thermosensitive film is read through the contacts; the supporting cantilever is used to suspend the coupling module, part of the circuit structure, and the thermosensitive film, and separate and insulate them from the substrate module.

[0010] A further technical solution of the present invention is: the coupling module is a composite metasurface absorbing structure, located at the top of the entire detector and directly exposed to terahertz waves; the composite metasurface absorbing structure is composed of a metal top layer, a dielectric layer, and a metal back plate from top to bottom, wherein the metal top layer is an array structure obtained by periodically arranging cross patches of two metals of different sizes and different materials.

[0011] A further technical solution of the present invention is: one type of cross patch is used as a peripheral cross patch, which forms a two-dimensional periodic array and divides the metal top layer into several square areas; the other type of cross patch is used as a central cross patch, which is arrayed in each square area and is concentric with the square area.

[0012] A further technical solution of the present invention is that the sizes of the two cross metal patches on the top layer of the coupling module satisfy: w2=w3, l 10 =l 11 +1μm, where w2 is the arm width of the peripheral cross patch, w3 is the arm width of the central cross patch, l 10 is the length of the arm of the cross patch at the center, l 11 is the length of the arms of the cross patch located at the periphery.

[0013] A further technical solution of the present invention is: the material of the supporting cantilever is silicon nitride, including an insulating layer, a cantilever and a pad; the insulating layer is a square flat plate, the coupling module is placed on the upper surface of the cantilever, and a thermosensitive film is attached to the lower surface; the cantilever is an L-shaped flat plate, and the two cantilevers are horizontally arranged on opposite sides of the insulating layer, and the short arm ends are respectively connected to the edges of the diagonal positions on the opposite sides of the insulating layer, and the long arm ends are respectively connected to the top ends of the two pads; the pads are placed on the substrate module.

[0014] A further technical solution of the present invention is that: the circuit structure is made of metal and comprises a connection layer, a connection block, a patch and a cylinder connected in sequence from top to bottom;

[0015] The connecting layer is a U-shaped flat plate, and two connecting layers are arranged on opposite sides of the heat-sensitive film. One arm of the U-shaped flat plate is connected to the heat-sensitive film, and the other arm end is connected to the top of the connecting block; and the connecting layer is closely attached to the lower surface of the insulating layer and the cantilever, and the other arm structure is consistent with the cantilever structure;

[0016] The two connecting blocks are respectively located on opposite sides of the two cushion blocks;

[0017] The two patches are respectively located between the two pads and the substrate module;

[0018] The top ends of the two cylinders are connected to the two patches respectively, and the bottom ends of the two cylinders pass through the substrate module and are connected to the contacts.

[0019] A further technical solution of the present invention is that the heat-sensitive film is a square plate made of vanadium oxide.

[0020] A further technical solution of the present invention is: the contacts are two rectangular flat plates located at the bottom of the substrate module and are made of gold.

[0021] A further technical solution of the present invention is: the substrate module is a silicon wafer, and two through holes are opened at the diagonal positions of its end surface. The cylinder of the readout module passes through the through holes to connect the bottom contact with the patch on the upper surface.

[0022] A further technical solution of the present invention is: the structural parameters of the detector are as follows:

[0023]

[0024]

[0025] Among them, w1 is the distance from the central axis of the cylinder in the circuit structure to the side wall of the substrate module, w2 is the arm width of the peripheral cross patch, w3 is the arm width of the central cross patch, r1 is the diameter of the cylinder in the circuit structure, g1 is the distance from the top corner of the contact edge to the adjacent side of the alignment frame, g2 is the distance between two contacts, p is the center distance between two adjacent peripheral cross patches, p0 is the side length of the square section of the substrate module, t1 is the thickness of the detector layer 1, that is, the contact thickness, t2 is the thickness of the detector layer 2, that is, the height of the substrate module, t3 is the thickness of the detector layers 3 and 5, that is, the patch and the thermal film The thickness of the detector is t4, t5 is the thickness of the detector layer 7 and 9, that is, the thickness of the metal back plate and the top layer, t6 is the thickness of the detector layer 8, that is, the thickness of the dielectric layer, t7 is the height of the supporting cantilever, l1 is the length of the long side of the contact, l1 is the length of the short side of the contact, l3 is the side length of the square metal patch, l4 is the length of the short side of the rectangular cross-section of the connecting block, l5 is the length of the long side of the rectangular cross-section of the connecting block, l6 is the width of the U-shaped flat plate of the connecting layer connected to the thermal film, l7 is the side length of the thermal film, l8 is the length of the cantilever, l9 is the side length of the insulating layer, l 10 is the length of the arm of the cross patch at the center, l 11 is the length of the arms of the cross patch located at the periphery.

[0026] Beneficial effects

[0027] The beneficial effects of the present invention are as follows: the present invention is a terahertz detector based on a metasurface and a thermosensitive film, which adopts a composite unit metasurface absorbing structure and has an operating band of 5.14-5.7THz. Compared with existing terahertz detectors, the present invention uses a metasurface absorbing structure as a coupling module, thereby achieving an absorption rate of over 90%, which is much higher than that of natural absorbing films. At the same time, the thermosensitive film is used to characterize the terahertz radiation power, and the resistance change of the thermosensitive film is output to the contact through the circuit structure, and finally the detector response curve is obtained as shown in FIG. Figure 5 As shown, the response time is 80ms, which basically achieves high-sensitivity real-time detection at room temperature.

[0028] The structural parameters of each layer of the detector of the present invention are as follows: Figure 2 As shown, Figure 2 The outermost boxes in (c)-(k) are alignment boxes, used to align the structures of each layer. The side length p0 of this box is the period size of the detector when forming the focal plane array. Multi-physics field simulation of the detector shows that its photothermal response is: 8.4K / μW, that is, for every 1μW of terahertz radiation irradiating the detector, the temperature of the thermosensitive film rises by 8.4K. Combining the sheet resistance-temperature curve of the thermosensitive film, the response curve of the detector can be obtained as follows: Figure 5 Furthermore, transient simulations show that the detector temperature reaches a steady state after 80 ms, indicating a detector response time of 80 ms. Detector simulations were conducted at an ambient temperature of 293 K and standard atmospheric pressure. Therefore, the above results represent performance at room temperature and atmospheric pressure. This demonstrates that the detector of the present invention achieves high-sensitivity, real-time detection at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the detector module structure;

[0030] Figure 2 Schematic diagram of the detector layered structure; (a) axonometric view of the detector as a whole, (b) side view of the detector layered structure, (c) detector layer 1 - contacts, (d) detector layer 2 - substrate and cylinders, (e) detector layer 3 - square gold patches, (f) detector layer 4 - assembly of gold and silicon nitride, (g) detector layer 5 - assembly of vanadium oxide, silicon nitride, and gold, (h) detector layer 6 - silicon nitride structure, (i) detector layer 7 - assembly of gold and silicon nitride, (j) detector layer 8 - silicon nitride dielectric layer, (k) detector layer 9 - metal top layer;

[0031] Figure 3 Detector absorption spectrum;

[0032] Figure 4 Thermal film square resistance-temperature curve;

[0033] Figure 5 Detector response curve.

[0034] Explanation of reference numerals: 1. Detector, 2. Coupling module, 3. Readout module, 4. Substrate module, 5. Through hole. DETAILED DESCRIPTION

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0037] This embodiment provides a terahertz detector based on a metasurface and a thermosensitive film (hereinafter referred to as a detector), which involves the structural design of the detector. Figure 1 As shown, the detector structure can be divided into three modules: the coupling module, the readout module, and the substrate module. These three modules will first be explained functionally. The coupling module directly receives terahertz radiation, absorbing it and generating a temperature change based on the power of the received terahertz radiation. The readout module consists of four components: a thermosensitive film, a circuit structure, a supporting cantilever, and contacts. The thermosensitive film is in close contact with the coupling module and heats up as the coupling module's temperature rises, changing its resistance. The circuit structure connects the thermosensitive film to the contacts, allowing the film's resistance to be read through the contacts. The supporting cantilever suspends the coupling module, part of the circuit structure, and the thermosensitive film, separating them from the substrate to provide thermal isolation, which is essential for thermal detectors. The contacts, located at the bottom of the structure, are used to connect to equipment related to resistance readout. The substrate module is the base used to fabricate the detector. The substrate contains through-holes that house a portion of the readout module's circuit structure. Finally, the change in the detector's isomorphic resistance value represents the magnitude of the terahertz radiation power, completing terahertz detection.

[0038] The coupling module is a composite metasurface absorbing structure, located at the top of the entire detector, and will be directly irradiated by the terahertz wave. Figure 2In the layering shown in (b), the coupling module includes the 7th, 8th, and 9th layers, which are the metal top layer, dielectric layer, and metal backplane from top to bottom. In the present invention, a composite metasurface is used, and the metal top layer uses two metal cross patches of different sizes to be arranged periodically to obtain the coupling module. Figure 1 As shown in the figure, we use black and white to represent the two sizes of metal cross patches, thus clearly showing the positional relationship of the two metal cross patches. By taking advantage of the characteristics of the two different sizes of metal patches resonating at different high and low frequencies, we finally obtained the 5.14-5.7THz absorption band, with an absorption rate of more than 90% within the band, as shown in the figure. Figure 3 As shown. Compared with traditional natural absorbing films, the absorption rate of this coupling module is more than doubled. At the same time, because the cross structure has good rotational symmetry, and the two sizes of metal cross patches have taken into account the overall rotational symmetry of the metasurface when arranged, the coupling module has good polarization insensitivity. For terahertz waves incident at any polarization angle, the absorption band and in-band absorption rate can remain unchanged. At the same time, when the oblique incident angle is less than 40 degrees, the absorption band can be maintained at 5.14-5.7THz, and the in-band absorption rate is also maintained at above 90%.

[0039] Preferably, one of the cross patches is used as a peripheral cross patch, which forms a two-dimensional periodic array and divides the metal top layer into several square areas; the other cross patch is used as a central cross patch, which is arrayed in each square area and is concentric with the square area.

[0040] Preferably, the coupling module satisfies the following requirements through the sizes of the two cross metal patches on the top layer: w2=w3, l 10 =l 11 +1μm, where w2 is the arm width of the peripheral cross patch, w3 is the arm width of the central cross patch, l 10 is the length of the arm of the cross patch at the center, l 11 is the length of the arms of the cross patch located at the periphery.

[0041] The readout module includes four parts: a thermosensitive film, a circuit structure, a supporting cantilever, and a contact.

[0042] The supporting cantilever is made of silicon nitride and includes an insulating layer, a cantilever and a pad; the insulating layer is a square flat plate with a coupling module placed on its upper surface and a thermosensitive film attached to its lower surface; the cantilever is an L-shaped flat plate, with two cantilevers horizontally arranged on opposite sides of the insulating layer, with the short arm ends respectively connected to the diagonal edges of the opposite sides of the insulating layer, and the long arm ends respectively connected to the top ends of the two pads; the pads are placed on the substrate module.

[0043] The circuit structure is made of metal and includes a connection layer, a connection block, a patch and a cylinder connected in sequence from top to bottom; the connection layer is a U-shaped flat plate, and the two connection layers are arranged on opposite sides of the thermosensitive film, one side arm of the U-shaped flat plate is connected to the thermosensitive film, and the other side arm end is connected to the top of the connection block; and the connection layer is tightly attached to the insulating layer and the lower surface of the cantilever, and its other side arm structure is consistent with the cantilever structure; the two connection blocks are respectively located on opposite sides of the two pads; the two patches are respectively located between the two pads and the substrate module; the top ends of the two cylinders are respectively connected to the two patches, and the bottom ends pass through the substrate module and are connected to the contacts.

[0044] The heat-sensitive film is a square plate made of vanadium oxide.

[0045] The contacts are two rectangular flat plates located at the bottom of the substrate module and are made of gold.

[0046] The detector of this embodiment is described from bottom to top according to the positional relationship between the structures. Figure 2 (b) shows the layering, with the first layer at the bottom. The structure in the first layer is the contact, which is made of gold; the two cylindrical structures in the second layer are exactly the same, as shown in Figure 2 As shown in (d), both are made of gold and are part of the circuit structure, used to establish circuit connections between contacts and other circuit structures; the third layer contains two completely identical squares, made of gold, as shown in Figure 2 (e) is part of the circuit structure; the fourth layer contains two materials, silicon nitride and gold, as shown in Figure 2 As shown in (f), silicon nitride is part of the cantilever support, which is used to support the circuit structure, coupling module, and thermal module to achieve thermal isolation, while the metal is part of the circuit structure; the fifth layer contains three materials: vanadium oxide, silicon nitride, and gold. Figure 2 As shown in (g), vanadium oxide is a thermosensitive film, silicon nitride is part of the supporting cantilever, and the metal is part of the circuit structure. The circuit structure is now introduced. The function of the circuit structure is to establish a circuit connection between the two sides of the vanadium oxide film (i.e., the thermosensitive film) and the two contacts. The square resistance of the vanadium oxide (i.e., the thermosensitive film) will change after being heated. The resistance signal can be transmitted to the contacts through the circuit structure. Finally, the square resistance change of the thermosensitive film can be read through the contacts to obtain the temperature change, and then the terahertz radiation power can be obtained. The square resistance-temperature curve of the thermosensitive film is shown in FIG. Figure 4As shown in the figure, the sixth and eighth layers contain only silicon nitride structures. The silicon nitride on both sides of the sixth layer forms part of the cantilever support, while the square silicon nitride in the middle is an insulating layer, preventing a circuit path from forming between the circuit structure in the fifth layer and the gold structure in the seventh layer. The silicon nitride on both sides of the eighth layer forms part of the cantilever support, while the square silicon nitride in the middle helps the coupling module in the ninth layer resonate, thereby absorbing terahertz radiation. The seventh layer contains both gold and silicon nitride. The silicon nitride structure forms part of the cantilever support, while the gold structure serves as a metal ground, helping the coupling module in the ninth layer resonate and absorb terahertz radiation.

[0047] The substrate module is a silicon wafer with an array of through holes etched on it, which is used as a base when preparing the detector. Figure 2 (b) shows the second layer of the layer, Figure 2 In (d), it can be clearly seen that the substrate module has through holes etched therein and filled with metal pillars of the readout module.

[0048] The structure of the detector is as described above, and the structural parameters of each layer of the detector are as follows: Figure 2 As shown, Figure 2 The outermost boxes in (c)-(k) are alignment boxes, used to align the structures of each layer. The side length p0 of these boxes is the periodicity of the detectors forming the focal plane array. Specific structural parameters of the detectors are shown in Table 1.

[0049] Table 1 Detector structural parameter values

[0050]

[0051] Among them, w1 is the distance from the central axis of the cylinder in the circuit structure to the side wall of the substrate module, w2 is the arm width of the peripheral cross patch, w3 is the arm width of the central cross patch, r1 is the diameter of the cylinder in the circuit structure, g1 is the distance from the top corner of the contact edge to the adjacent side of the alignment frame, g2 is the distance between two contacts, p is the center distance between two adjacent peripheral cross patches, p0 is the side length of the square section of the substrate module, t1 is the thickness of the detector layer 1, that is, the contact thickness, t2 is the thickness of the detector layer 2, that is, the height of the substrate module, t3 is the thickness of the detector layers 3 and 5, that is, the patch and the thermal film The thickness of the detector is t4, t5 is the thickness of the detector layer 7 and 9, that is, the thickness of the metal back plate and the top layer, t6 is the thickness of the detector layer 8, that is, the thickness of the dielectric layer, t7 is the height of the supporting cantilever, l1 is the length of the long side of the contact, l1 is the length of the short side of the contact, l3 is the side length of the square metal patch, l4 is the length of the short side of the rectangular cross-section of the connecting block, l5 is the length of the long side of the rectangular cross-section of the connecting block, l6 is the width of the U-shaped flat plate of the connecting layer connected to the thermal film, l7 is the side length of the thermal film, l8 is the length of the cantilever, l9 is the side length of the insulating layer, l 10 is the length of the arm of the cross patch at the center, l 11 is the length of the arms of the cross patch located at the periphery.

[0052] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A terahertz photothermal detector based on metasurface loading, characterized by: It includes a coupling module, a readout module and a substrate module, wherein the coupling module is used to absorb terahertz radiation and generate temperature changes; The readout module includes a thermosensitive film, a circuit structure, a supporting cantilever, and contacts. The thermosensitive film is applied to the back of the coupling module and connected to the contacts via the circuit structure, and the resistance of the thermosensitive film is read via the contacts. The supporting cantilever is used to suspend the coupling module, part of the circuit structure, and the thermosensitive film, and to separate and insulate it from the substrate module. The coupling module is a composite metasurface absorbing structure located on top of the entire detector and directly exposed to terahertz waves. The composite metasurface absorbing structure consists of a metal top layer, a dielectric layer, and a metal back plate from top to bottom. The metal top layer is a periodically arranged array structure of cross-shaped patches made of two different sizes and materials. The support cantilever is made of silicon nitride and includes an insulating layer, a cantilever, and a pad. The insulating layer is a square flat plate with a coupling module placed on its upper surface and a heat-sensitive film attached to its lower surface. The cantilever is an L-shaped flat plate, with two cantilevers horizontally arranged on opposite sides of the insulating layer, with the short arm ends connected to the diagonal edges of the insulating layer on opposite sides, and the long arm ends connected to the top ends of the two pads. The pads are placed on the substrate module. The circuit structure is made of metal and includes a connection layer, a connection block, a patch and a cylinder connected in sequence from top to bottom; The connecting layer is a U-shaped flat plate, and two connecting layers are arranged on opposite sides of the heat-sensitive film. One arm of the U-shaped flat plate is connected to the heat-sensitive film, and the other arm end is connected to the top of the connecting block; and the connecting layer is closely attached to the lower surface of the insulating layer and the cantilever, and the other arm structure is consistent with the cantilever structure; The two connecting blocks are respectively located on opposite sides of the two cushion blocks; The two patches are respectively located between the two pads and the substrate module; The top ends of the two cylinders are connected to the two patches respectively, and the bottom ends of the two cylinders pass through the substrate module and are connected to the contacts; The heat-sensitive film is a square plate made of vanadium oxide.

2. The terahertz photothermal detector based on metasurface loading according to claim 1, characterized in that: One type of cross patch is used as a peripheral cross patch, which forms a two-dimensional periodic array and divides the metal top layer into several square areas; the other type of cross patch is used as a central cross patch, which is arrayed in each square area and is concentric with the square area.

3. The terahertz photothermal detector based on metasurface loading according to claim 1, characterized in that: The sizes of the two cross metal patches on the top layer of the coupling module satisfy: w2=w3, l 10 =l 11 +1μm, where w2 is the arm width of the peripheral cross patch, w3 is the arm width of the central cross patch, l 10 is the length of the arm of the cross patch at the center, l 11 is the length of the arms of the cross patch located at the periphery.

4. The terahertz photothermal detector based on metasurface loading according to claim 1, characterized in that: The contacts are two rectangular flat plates located at the bottom of the substrate module and are made of gold.

5. The terahertz photothermal detector based on metasurface loading according to claim 1, characterized in that: The substrate module is a silicon wafer with two through holes at diagonal positions on its end faces. The cylinder of the readout module passes through the through holes to connect the bottom contact with the patch on the upper surface.

6. The terahertz photothermal detector based on metasurface loading according to any one of claims 1 to 5, characterized in that: The structural parameters of the detector are as follows: Among them, w1 is the distance from the central axis of the cylinder in the circuit structure to the side wall of the substrate module, w2 is the arm width of the peripheral cross patch, w3 is the arm width of the central cross patch, r1 is the diameter of the cylinder in the circuit structure, g1 is the distance from the top corner of the contact edge to the adjacent side of the alignment frame, g2 is the distance between two contacts, p is the center distance between two adjacent peripheral cross patches, p0 is the side length of the square section of the substrate module, t1 is the thickness of the detector layer 1, that is, the contact thickness, t2 is the thickness of the detector layer 2, that is, the height of the substrate module, t3 is the thickness of the detector layers 3 and 5, that is, the patch and the thermal film The thickness of the detector is t4, t5 is the thickness of the detector layer 7 and 9, that is, the thickness of the metal back plate and the top layer, t6 is the thickness of the detector layer 8, that is, the thickness of the dielectric layer, t7 is the height of the supporting cantilever, l1 is the length of the long side of the contact, l2 is the length of the short side of the contact, l3 is the side length of the square metal patch, l4 is the length of the short side of the rectangular cross-section of the connecting block, l5 is the length of the long side of the rectangular cross-section of the connecting block, l6 is the width of the U-shaped flat plate connecting the thermal film on one side, l7 is the side length of the thermal film, l8 is the length of the cantilever, l9 is the side length of the insulating layer, l 10 is the length of the arm of the cross patch at the center, l 11 is the length of the arms of the cross patch located at the periphery.

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