3D terahertz metasurface sensor with space height

Abstract

The invention provides a 3D terahertz metasurface sensor with spatial height, and relates to the field of terahertz wave detection, and the sensor comprises a substrate which is made of a material with high permeability to terahertz waves; each unit cell unit is provided with an opening resonance ring assembly and a height-adjustable metal rod assembly arranged in the middle of an opening resonance ring, and the multiple unit cell units are integrated to the surface of the substrate to form a super-surface array; wherein the split resonant ring assembly comprises a pair of symmetrical resonant rings, the two opposite sides of the two resonant rings are provided with openings, the height-adjustable metal rod assembly comprises metal rods of various heights, the metal rods are arranged in the middle of an area defined by the resonant rings, and the width of the metal rods is smaller than that of the resonant rings. The metal rod is flush with or exceeds the resonant ring in the vertical height direction. The sensor has excellent performance of high sensitivity in the aspect of terahertz sensing.

Description

Technical Field

[0001] This invention relates to the field of terahertz wave detection technology, and more specifically, to a 3D terahertz metasurface sensor with spatial height. Background Technology

[0002] Terahertz sensing technology, with its advantages of being non-destructive and capable of fingerprint spectral recognition, holds immense application potential in biomedical detection and materials analysis. However, the interaction between traditional terahertz sensors and analytes is typically weak, making it difficult to meet the stringent requirements for detecting trace biomolecules in terms of sensitivity and detection limits. Metasurfaces, as artificially designed two-dimensional planar structures, can freely manipulate electromagnetic waves through the ingenious design of subwavelength unit structures, providing an effective way to enhance the interaction between light and matter. Existing terahertz metasurface sensors are mostly based on planar structures, and their resonant modes (such as dipole resonances) are easily affected by radiation losses, resulting in generally low quality factors (Q values). This limits the sensor's ability to resolve minute frequency shifts, thus restricting further improvements in detection sensitivity. Therefore, designing a novel metasurface structure capable of exciting high-intensity, high-Q resonant modes to achieve highly sensitive detection of trace biomolecules has become a key challenge in the development of this technology. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art or related technologies, and provides a 3D terahertz metasurface sensor with spatial height, which can improve the sensitivity of detecting trace biomolecules.

[0004] This invention is achieved through the following technical solution: a 3D terahertz metasurface sensor with spatial height, comprising: a substrate made of a material with high transmittance to terahertz waves; a unit cell having an open resonant ring assembly and a height-adjustable metal rod assembly disposed in the middle of the open resonant ring, wherein multiple unit cells are integrated onto the surface of the substrate to form a metasurface array; wherein, the open resonant ring assembly includes a pair of symmetrical resonant rings, the two resonant rings being arranged opposite each other with openings on both sides, and the height-adjustable metal rod assembly includes metal rods of various heights, the metal rods being disposed in the middle of the area enclosed by the resonant rings, the width of the metal rods being smaller than the width of the resonant rings, and the metal rods being flush with or extending beyond the resonant rings in the vertical height direction.

[0005] In this technical solution, the 3D terahertz metasurface sensor with spatial height is based on anapole resonance. By using the "height" of the rod-shaped structure as an independent key design parameter, destructive interference is achieved between the electric dipoles generated by the metal nanoparticles or antennas in the nanostructure and the ring dipoles generated by the ring or spiral shape of the nanostructure. This constructs a 3D terahertz metasurface biosensor with a specific resonant frequency, high Q resonant response, and height-controlled Anapole mode, enabling effective control of the anapole resonant mode. The anapole mode originates from the destructive interference between the electric dipole and the ring dipole, which can significantly suppress radiation loss, thereby obtaining a sharp high-Q resonant response and achieving high-sensitivity detection.

[0006] The 3D terahertz metasurface sensor with spatial height provided by the present invention preferably has a substrate made of quartz and a substrate height (thickness) of 2 mm.

[0007] The 3D terahertz metasurface sensor with spatial height provided by the present invention preferably has an aluminum resonant ring and an aluminum metal rod.

[0008] The 3D terahertz metasurface sensor with spatial height provided by the present invention preferably has a period of 70 μm for a single unit cell.

[0009] The 3D terahertz metasurface sensor with spatial height provided by the present invention preferably has a metal rod with a length of 36 μm and a width of 5 μm.

[0010] According to the 3D terahertz metasurface sensor with spatial height provided by the present invention, preferably, the vertical height of the metal rod is 100nm, 400nm, 1000nm or 2000nm; the vertical height of the metal rod is adjusted according to the object to be measured.

[0011] The 3D terahertz metasurface sensor with spatial height provided by the present invention preferably has a resonant ring with a height of 100 nm, a length of 45 μm, a maximum width of 10 μm at both ends, and a minimum width of 6 μm in the middle.

[0012] According to the 3D terahertz metasurface sensor with spatial height provided by the present invention, preferably, the method for fabricating the cell unit integrated on the substrate includes: using a quartz substrate with a thickness of 2 mm, sequentially cleaning with acetone solution, ultrasonic treatment, rinsing with deionized water and drying with nitrogen to complete the substrate pretreatment; subsequently, spin-coating a 100 nm thick photoresist on the front side of the substrate, performing ultraviolet lithography patterning through a mask, and then sequentially depositing a 10 nm thick titanium adhesion layer and a 100 nm thick aluminum thin film by magnetron sputtering; after removing excess material using a deep silicon etching process, sequentially spin-coating photoresists with heights of 100 nm, 400 nm, 1000 nm and 2000 nm, and repeating the above lithography and metal deposition steps to prepare the intermediate rod-shaped structure layer by layer.

[0013] The beneficial effects achieved by this invention include at least the following: The unit cell innovatively integrates a pair of symmetrical open resonant rings and a height-tunable metal rod structure. By using the "height" of the rod structure as an independent key design parameter, effective control of the anapole resonant mode is achieved. The anapole mode originates from the destructive interference between an electric dipole and a ring dipole, which can significantly suppress radiation loss, thereby obtaining a sharp, high-Q resonant response. By optimizing the height parameter of the metal rod, the resonant frequency and field distribution can be precisely controlled. This design enables the sensor to possess extremely high electromagnetic field localization enhancement capability and environmental refractive index sensitivity in the terahertz band, providing an advanced platform for achieving highly sensitive and reliable biomedical sensing. Attached Figure Description

[0014] Figure 1 A schematic diagram of the microstructure of a 3D terahertz metasurface sensor with spatial height according to an embodiment of the present invention is shown.

[0015] Figure 2 A top view of the structural unit of a 3D terahertz metasurface sensor with spatial height according to an embodiment of the present invention is shown.

[0016] Figure 3 A side view of the structural unit of a 3D terahertz metasurface sensor with spatial height according to an embodiment of the present invention is shown. Detailed Implementation

[0017] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, one embodiment of the present invention discloses a 3D terahertz metasurface sensor with spatial height, comprising: a substrate 1, made of a material having high transmittance to terahertz waves; Unit 2 has an open resonant ring assembly and a height-adjustable metal rod assembly located in the middle of the open resonant ring. Multiple unit cells are integrated onto the substrate surface to form a metasurface array. The open resonant ring assembly includes a pair of symmetrical resonant rings with openings on both sides. The height-adjustable metal rod assembly includes metal rods of various heights. The metal rods are located in the middle of the area enclosed by the resonant rings. The width of the metal rods is smaller than the width of the resonant rings. The metal rods are flush with or extend beyond the resonant rings in the vertical height direction.

[0019] In this embodiment, under resonant conditions, the incident terahertz electric field induces significant surface charge accumulation between the metallic structures, thereby forming an extremely strong local electric field around the central structure. In the anapole resonant mode, the electric field intensity is distributed along the central rod-shaped structure. The resulting stimulated electromagnetic hotspots spatially highly overlap with the analyte, thus greatly enhancing the interaction strength between the terahertz wave and the analyte.

[0020] like Figure 2 As shown, the 3D terahertz metasurface sensor with spatial height provided in the above embodiment further includes a substrate material of quartz with a thickness of 2 mm; a resonant ring material of aluminum; and a metal rod material of aluminum; the period of a single unit cell is... P The diameter is 70 μm; the length a of the metal rod is 36 μm, and the width e is 5 μm; the height of the resonant ring is 100 nm, and the length is... b The diameter is 45 μm, the widest point at both ends is 10 μm, and the narrowest point in the middle is... d It is 6μm.

[0021] like Figure 3 As shown, according to the 3D terahertz metasurface sensor with spatial height provided in the above embodiment, further, the height of the metal rod... h The wavelength range is 100nm, 400nm, 1000nm, or 2000nm; the vertical height of the metal rod is adjusted according to the object being tested.

[0022] According to another embodiment of the present invention, a method for fabricating a 3D terahertz metasurface sensor with spatial height provided in the above embodiment is also disclosed: using a quartz substrate with a thickness of 2 mm, the substrate is pretreated by sequentially cleaning with acetone solution, ultrasonic treatment, rinsing with deionized water and drying with nitrogen gas; then, a 100 nm thick photoresist is spin-coated on the front side of the substrate, and ultraviolet lithography patterning is performed through a mask, followed by sequential deposition of a 10 nm thick titanium adhesion layer and a 100 nm thick aluminum thin film by magnetron sputtering; after removing excess material using a deep silicon etching process, photoresist with heights of 100 nm, 400 nm, 1000 nm and 2000 nm is spin-coated sequentially, and the above lithography and metal deposition steps are repeated to prepare an intermediate rod-shaped structure layer by layer.

[0023] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A 3D terahertz metasurface sensor with spatial height, characterized in that, include: The substrate is made of a material that is highly transparent to terahertz waves; A unit cell has an open resonant ring assembly and a height-adjustable metal rod assembly located in the middle of the open resonant ring, and multiple unit cells are integrated onto the substrate surface to form a metasurface array. The open resonant ring assembly includes a pair of symmetrical resonant rings, which are arranged opposite each other with openings on both sides. The height-adjustable metal rod assembly includes metal rods of various heights, which are located in the middle of the area enclosed by the resonant rings. The width of the metal rod is smaller than the width of the resonant rings, and the metal rod is flush with or extends beyond the resonant rings in the vertical height direction.

2. The 3D terahertz metasurface sensor according to claim 1, characterized in that, The substrate is made of quartz and has a thickness of 2 mm.

3. The 3D terahertz metasurface sensor according to claim 1, characterized in that, The resonant ring is made of aluminum, and the metal rod is also made of aluminum.

4. The 3D terahertz metasurface sensor according to claim 1, characterized in that, The period of a single unit cell is 70 μm.

5. The 3D terahertz metasurface sensor according to claim 1, characterized in that, The metal rod is 36 μm long and 5 μm wide.

6. The 3D terahertz metasurface sensor according to claim 5, characterized in that, The vertical height of the metal rod is 100nm, 400nm, 1000nm, or 2000nm; the vertical height of the metal rod is adjusted according to the object to be tested.

7. The 3D terahertz metasurface sensor according to claim 1, characterized in that, The resonant ring has a height of 100 nm, a length of 45 μm, a maximum width of 10 μm at both ends, and a minimum width of 6 μm in the middle.

8. The 3D terahertz metasurface sensor according to any one of claims 1 to 7, characterized in that, The method for fabricating the unit cell integrated on the substrate includes: Using a quartz substrate with a thickness of 2 mm, the substrate pretreatment was completed by sequentially cleaning with acetone solution, ultrasonic treatment, rinsing with deionized water and drying with nitrogen gas. Subsequently, a 100nm thick photoresist was spin-coated on the front side of the substrate, and ultraviolet lithography patterning was performed using a mask. Then, a 10nm thick titanium adhesion layer and a 100nm thick aluminum film were deposited sequentially by magnetron sputtering. After removing excess material using deep silicon etching, photoresist with heights of 100nm, 400nm, 1000nm and 2000nm is spin-coated sequentially, and the above photolithography and metal deposition steps are repeated to prepare the intermediate rod-shaped structure layer by layer.

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