A micro-nanostructure with local enhancement of electromagnetic fields in terahertz and near-infrared dual bands

Abstract

The present invention belongs to the technical field of micro-nano structures for local enhancement of electromagnetic fields, and specifically relates to a micro-nano structure for local enhancement of electromagnetic fields in dual bands of terahertz and near-infrared, including a near-infrared band capture structure and a terahertz band local field enhancement structure, wherein the terahertz band local field enhancement structure is etched on the near-infrared band capture structure. The present invention combines the near-infrared band capture structure with the terahertz band local field enhancement structure to achieve stable capture of biomolecules in the near-infrared band and enhance the terahertz resonance signal of biomolecules. The present invention utilizes the characteristics of local surface plasma enhancement of gold nanostructures. After the laser beam is focused by a high numerical aperture objective lens and irradiated on the surface of the metal layer, an optical capture field can be generated, thereby achieving the capture of biomolecules in the near-infrared band; a rectangular groove with a length of micrometer scale and a width of nanometer scale is used to achieve local field enhancement in the terahertz band.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-nano structures for local enhancement of electromagnetic fields, and in particular relates to a micro-nano structure for local enhancement of electromagnetic fields in dual bands of terahertz and near-infrared. Background Art

[0002] Organisms process information through neurons to generate instructions and control various functions and activities. Neurons can maintain dynamic growth through neural microtubules and assist protein transport, among which protein molecule vibration can generate electromagnetic signals for information exchange. At present, protein molecule vibration spectrum measurement mainly focuses on high-frequency (300cm -1 —5000cm -1 ), such as infrared spectroscopy, Raman spectroscopy and terahertz time-domain spectroscopy. In infrared spectroscopy, the hydroxyl peak in water interferes with the determination, so it is not suitable for analyzing water-containing samples. At the same time, the error is large and the sensitivity is low in quantitative analysis. In Raman spectroscopy, although the interference from water is weak, proteins or other organisms in aqueous solutions, such as cells, bacteria, viruses, etc., can be analyzed. However, due to the inherent low scattering probability of the Raman process, Raman scattering is a weak phenomenon, and the low cross-section of proteins makes it difficult to obtain high-quality Raman signals. In terahertz time-domain spectroscopy (THz-TDS), it is required to be carried out in the crystalline state of the protein, and it is impossible to detect the free vibration state of a single protein molecule in a solution environment and the low-frequency vibration influence of the dipole action of water molecules.

[0003] At present, the measurement of protein molecular vibration spectrum is mainly limited to the strong absorption of water by signals in a solution environment, which makes it difficult to collect and process the signals. At the same time, there is a lack of micro-nanostructure design for stably capturing protein molecules in both the terahertz band and the near-infrared band and enhancing the terahertz signal. Summary of the invention

[0004] In view of the technical problem that the current measurement of protein molecule vibration spectrum is mainly limited to the strong absorption of water by signals in a solution environment, which makes it difficult to collect and process the signals, the present invention provides a micro-nano structure with local enhancement of terahertz and near-infrared dual-band electromagnetic fields, and simultaneously utilizes a combination of near-infrared band nanostructures and terahertz band micro-nano structures to achieve the capture of biological molecules in the near-infrared band and enhance the terahertz signals of biological molecules.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A micro-nano structure with local enhancement of terahertz and near-infrared dual-band electromagnetic fields comprises a near-infrared band capture structure and a terahertz band local field enhancement structure, wherein the terahertz band local field enhancement structure is etched on the near-infrared band capture structure.

[0007] The near-infrared band capture structure comprises a metal film layer and a silicon dioxide substrate, wherein the metal film layer is arranged on the silicon dioxide substrate.

[0008] The terahertz band local field enhancement structure is etched on the metal film layer.

[0009] The terahertz band local field enhancement structure is a rectangular groove structure with a length of micrometer level and a width of nanometer level.

[0010] Nanostructures of different sizes are etched on the metal film layer, and the nanostructures are butterfly structures, rectangular block structures, and disk structures.

[0011] The thickness of the metal film layer is 150 nm.

[0012] The length of the rectangular groove structure of the terahertz band local field enhancement structure is 100um-200um, and the width is less than or equal to 200nm.

[0013] A fixed laser and a tunable laser are arranged on one side of the near-infrared band capture structure and the terahertz band local field enhancement structure, and the nanostructure on the near-infrared band capture structure and the rectangular groove structure on the terahertz band local field enhancement structure are both arranged in the optical path direction of the fixed laser and the tunable laser.

[0014] A control method for a micro-nanostructure with local enhanced electromagnetic fields in terahertz and near-infrared dual-bands comprises the following steps: by applying two laser beams, one of which is a fixed laser and the other is a tunable laser, the frequency difference between the two laser beams is changed by the tunable laser to generate a beat frequency signal with a terahertz envelope frequency; in the near-infrared band, the laser beam is focused by an objective lens with a high numerical aperture and irradiated on a nanostructure of a metal film layer to generate an optical capture field, and due to the action of a gradient force, biological molecules or particles in a solution are captured in the nanostructure; the terahertz beat frequency signal generated by the dual lasers acts on the biological molecules or particles to generate terahertz resonance therewith, and at the same time, the nanostructure is combined with a terahertz band local field enhancement structure to enhance the terahertz resonance signal acting on the biological molecules or particles, which is beneficial to the detection of the terahertz resonance signal of the biological molecules or particles.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention includes a near-infrared band capture structure and a terahertz band local field enhancement structure. The present invention combines the near-infrared band capture structure with the terahertz band local field enhancement structure to achieve stable capture of biomolecules in the near-infrared band and enhance the terahertz resonance signal of biomolecules. The present invention utilizes the characteristics of local surface plasma enhancement of gold nanostructures. After the laser beam is focused by a high numerical aperture objective lens and irradiated on the surface of the metal layer, an optical capture field can be generated to achieve the capture of biomolecules in the near-infrared band; a rectangular groove with a length of micrometer scale and a width of nanometer scale is used to achieve local field enhancement in the terahertz band. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0018] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0019] Figure 1 It is a three-dimensional schematic diagram of the structure of the present invention;

[0020] Figure 2 It is a top view of the structure of the present invention;

[0021] Figure 3 This is a schematic diagram of the near-infrared band capture structure of the present invention;

[0022] Figure 4 This is the transmission characteristic curve of the rectangular slot in the terahertz band of the present invention;

[0023] Figure 5 This is the XZ electric field distribution diagram of the rectangular slot in the terahertz band of the present invention;

[0024] Figure 6 It is a transmission characteristic curve diagram of the disk structure in the near infrared band of the present invention;

[0025] Figure 7 This is the XY electric field distribution diagram of the disk structure in the near-infrared band of the present invention.

[0026] Among them: 1 is a near-infrared band capture structure, 2 is a terahertz band local field enhancement structure, 101 is a metal film layer, 102 is a silicon dioxide substrate, 103 is a butterfly structure, 104 is a rectangular block structure, and 105 is a disk structure. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. These descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0028] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0030] In this embodiment, if Figure 1 , Figure 2 As shown, a micro-nano structure design for local enhancement of electromagnetic fields in terahertz and near-infrared dual-bands includes: a near-infrared band capture structure 1, a 150nm metal film layer 3 and a terahertz band local field enhancement structure 2. The near-infrared band capture structure 1 includes a metal film layer 3 and a silicon dioxide substrate 4. The metal film layer 3 is formed on the silicon dioxide substrate 4, and the metal film layer 3 is etched with nanostructures: a butterfly structure 103, a rectangular block structure 104, and a disk structure 105; the terahertz band local field enhancement structure 2 is formed on the metal film layer 3, and the metal film layer 3 is etched with a rectangular groove structure with a length of micrometer level and a width of nanometer level.

[0031] like Figure 1 , 3As shown, the near-infrared band capture structure 1 includes: a metal film layer 3 and a silicon dioxide substrate 4. The metal film layer 3 is etched with a nanostructure. In this preferred embodiment, the radius of the disk structure 105 is 65nm, and the center distance between the two disks is 150nm. The nanostructure will produce a local plasma optical effect under laser irradiation. The laser beam can generate an optical capture field when it is focused by a high numerical aperture objective lens and irradiated on the surface of the metal layer, thereby achieving the capture of biological molecules in the near-infrared band.

[0032] like Figure 1 , Figure 2 As shown, the metal film layer 3 is etched with a rectangular groove with a length of micrometer level and a width of nanometer level. In the preferred embodiment, in order to make the terahertz resonance within the range of 0.5-1THz, the length of the rectangular groove structure in the terahertz band local field enhancement structure 2 is 100um-200um, and the width of the rectangular groove structure of the terahertz band local field enhancement structure 2 can be less than or equal to 200nm according to the nano-processing technology. In the present embodiment, the width of the rectangular groove structure of the terahertz band local field enhancement structure 2 is preferably 200nm.

[0033] Electromagnetic simulation software was used to simulate and analyze the electric field distribution and transmission characteristics of the structure design of the present invention in the near-infrared band and the terahertz band. As shown in Figures 4 and 5, the simulation results in the terahertz band, in the terahertz band local field enhancement structure 2, the rectangular groove structure with a length of 100um and a width of 200 nanometers achieved an electric field enhancement of about 1200 times at 0.98THz, and the transmission characteristic curve can also be seen to have a corresponding resonance peak at 0.98THz; Figure 6 , 7 As shown, the disk structure 105 is simulated and analyzed in the near-infrared band. From the transmission characteristic curve, it can be seen that there is resonance enhancement near 850nm, and the electric field in the XY direction is enhanced by 50 times.

[0034] The working principle of the present invention is: by adding two laser beams, one is a fixed laser and the other is a tunable laser, the frequency difference between the two laser beams is changed by the tunable laser, and a beat frequency signal with a terahertz envelope frequency is generated; in the near-infrared band, the laser beam is focused by a high numerical aperture objective lens and irradiated on the metal nanostructure to generate an optical capture field, and due to the gradient force, the biological molecules or particles in the solution are captured in the nanostructure. The terahertz beat frequency signal generated by the dual lasers acts on the biological molecules or particles, generating terahertz resonance therewith, and at the same time, the nanostructure is combined with the terahertz band local field enhancement structure, so that the terahertz resonance signal acting on the biological molecules or particles is enhanced, which is conducive to the detection of the terahertz resonance signal of the biological molecules or particles.

[0035] Only the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the protection scope of the present invention.

Claims

1. A micro-nanostructure with local enhancement of terahertz and near-infrared dual-band electromagnetic fields, characterized by: The invention comprises a near-infrared band capture structure (1) and a terahertz band local field enhancement structure (2), wherein the terahertz band local field enhancement structure (2) is etched on the near-infrared band capture structure (1); the near-infrared band capture structure (1) comprises a metal film layer (101) and a silicon dioxide substrate (102), wherein the metal film layer (101) is arranged on the silicon dioxide substrate (102); nanostructures of different sizes are etched on the metal film layer (101), wherein the nanostructures are butterfly structures (103), rectangular block structures (104) or disk structures (105); and the terahertz band local field enhancement structure (2) is a rectangular groove structure with a length of micrometer order and a width of nanometer order, wherein the nanostructure is arranged in the rectangular groove structure.

2. The micro-nanostructure with local enhancement of terahertz and near-infrared dual-band electromagnetic fields according to claim 1, characterized in that: The terahertz band local field enhancement structure (2) is etched on the metal film layer (101).

3. The micro-nanostructure with local enhancement of terahertz and near-infrared dual-band electromagnetic fields according to claim 1, characterized in that: The thickness of the metal film layer (101) is 150 nm.

4. The micro-nanostructure with local enhancement of terahertz and near-infrared dual-band electromagnetic fields according to claim 1, characterized in that: The rectangular groove structure of the terahertz band local field enhancement structure (2) has a length of 100um-200um and a width of less than or equal to 200nm.

5. The micro-nanostructure with local enhancement of terahertz and near-infrared dual-band electromagnetic fields according to claim 1, characterized in that: A fixed laser and a tunable laser are arranged on one side of the near-infrared band capture structure (1) and the terahertz band local field enhancement structure (2), and the nanostructure on the near-infrared band capture structure (1) and the rectangular groove structure on the terahertz band local field enhancement structure (2) are both arranged in the optical path direction of the fixed laser and the tunable laser.

6. A control method for a micro-nanostructure with local enhancement of terahertz and near-infrared dual-band electromagnetic fields according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: applying two laser beams, one of which is a fixed laser and the other is a tunable laser, and changing the frequency difference between the two laser beams through the tunable laser to generate a beat frequency signal with an envelope frequency of terahertz; In the near-infrared band, after being focused by a high numerical aperture objective lens, the laser beam irradiates the nanostructure of the metal film layer to generate an optical capture field. Due to the gradient force, the biological molecules or particles in the solution are captured in the nanostructure; the terahertz beat frequency signal generated by the dual lasers acts on the biological molecules or particles, generating terahertz resonance with them. At the same time, the nanostructure is combined with the local field enhancement structure in the terahertz band, so that the terahertz resonance signal acting on the biological molecules or particles is enhanced, which is beneficial to the detection of terahertz resonance signals of biological molecules or particles.

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