One-dimensional ternary structure photonic crystal biological detection sensor and application

Abstract

The invention discloses a one-dimensional ternary structure photonic crystal biological detection sensor and application, and relates to the technical field of sensors. According to the one-dimensional ternary structure photonic crystal biological detection sensor, at least three unit cells, a first defect structure and at least three unit cells are sequentially arranged in the direction from an incident wave vector to an emergent wave vector, and the number of the unit cells located on the two sides of the first defect structure is the same; a first graphene layer, a middle layer and a second graphene layer are sequentially arranged in each unit cell, and the first defect structure comprises a detection layer; the one-dimensional ternary structure photonic crystal biological detection sensor further comprises a second defect structure. The one-dimensional ternary structure photonic crystal biological detection sensor can realize a refractive index sensing function in an omnidirectional photonic forbidden band, is good in transmission performance, wide in detection range and high in detection fault tolerance, can realize different types of sensing effects at different temperatures, has more functions, is relatively low in cost, and is suitable for more application scenes.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sensors, and particularly relates to a one-dimensional ternary structure photonic crystal biological detection sensor and application. BACKGROUND

[0002] With the development of optical materials, many optical devices with broad application prospects and novel functions, such as sensors, etc., have appeared. In the current many optical materials, graphene and phase change materials have anisotropy and other properties, which can be well applied in optical devices and improve their performance.

[0003] At present, there are some optical devices combining graphene and phase change materials, but most of them have the structure that the chemical potential of graphene needs to be increased as much as possible, and the double-mode defect mode formed makes the precision requirement of the detection equipment particularly high, which is almost difficult to realize in actual research and production. Moreover, the existing sensors containing graphene and phase change materials are almost binary structures. Under the same chemical potential, the band gap of the binary structure is small, resulting in small detection range and low detection efficiency of the sensor. Moreover, the working frequency of the existing sensors containing graphene and phase change materials is relatively fixed, and different sensing effects cannot be achieved at different frequency bands and different temperatures, so the application scene is limited. In addition, the working efficiency of the existing sensors containing graphene and phase change materials is low, and usually only one working parameter is good, and the remaining working parameters are poor, the working effect is uneven, and the real needs cannot be met. SUMMARY

[0004] The purpose of the present application is to overcome the above-mentioned deficiencies of the prior art, and to provide a one-dimensional ternary structure photonic crystal biological detection sensor and application, so as to solve the problems of small detection range, low detection efficiency, inability to achieve different sensing effects at different frequency bands / temperatures, uneven working effect, and inability to meet the real needs of the existing sensors containing graphene and phase change materials.

[0005] In order to achieve the above-mentioned application purposes, the present application proposes the following technical solutions:

[0006] In the first aspect, the present application provides a one-dimensional ternary structure photonic crystal biological detection sensor, which is arranged in sequence along the direction from the incident wave vector to the exit wave vector, and has at least three unit cells, a first defect structure and at least three unit cells, the number of the unit cells located on both sides of the first defect structure is the same, each unit cell is arranged in sequence with a first graphene layer, an intermediate layer and a second graphene layer, the first defect structure includes a detection layer, and any two adjacent structures are in contact.

[0007] The one-dimensional ternary structure photonic crystal biological detection sensor further comprises a second defect structure, which is located on one side of the first defect structure close to the exit wave vector, or the second defect structure is located on the side of all the unit cells away from the incident wave vector.

[0008] In some embodiments, the transmission process of the one-dimensional ternary structure photonic crystal biological detection sensor is analyzed by a transfer matrix method, and the dispersion relation is described by formula (4) and formula (5): TM wave polarization: Wherein, k x is the component of the wave in the x direction, k z is the component of the wave in the z direction, k0=2π / f, and is the initial wave vector, ε1 is the dielectric constant in the x direction, μ1 is the magnetic permeability in the x direction, ε3 is the dielectric constant in the z direction; the x direction is perpendicular to the thickness direction of the first graphene layer, the z direction is parallel to the thickness direction of the first graphene layer, and the x direction is perpendicular to the z direction;

[0009] According to the formula (4) and the formula (5), the electromagnetic relationship between the incident wave and the exit wave in the transmission process of the single-layer material under TE polarization and TM polarization is represented by a matrix form, and is described by formula (6) and formula (7):

[0010] Wherein, k z is the wave vector, d is the thickness of the single-layer medium, E1 y is the y direction electric field of the medium material 1 position under TE polarization, H1 x is the x direction magnetic field of the medium material 1 position under TE polarization, E2 y is the y direction electric field of the medium material 2 position under TE polarization, H2 x is the x direction magnetic field of the medium material 2 position under TE polarization; H1 y is the y direction magnetic field of the medium material 1 position under TM polarization, E1 x is the x direction electric field of the medium material 1 position under TM polarization, H2 y is the y direction magnetic field of the medium material 2 position under TM polarization, E2 x is the x direction electric field of the medium material 2 position under TM polarization, Η is the wave impedance, η is the process parameter, and is related to the polarization mode and material characteristics, η TE is the process parameter under TE polarization, described by formula (8): η TM is the process parameter under TM polarization, described by formula (9): wherein μ = relative permeability of the medium x μ0, μ0 = 4π x 10 -7 N / A, ε0 = 8.85 x 10 -12 (F / m) is a vacuum permittivity, ε1 is a permittivity of the medium in the x direction; the y direction is a direction perpendicular to the thickness direction of the first graphene layer, and the y direction is perpendicular to the x direction and the z direction respectively;

[0011] According to the formula (4), the formula (5), the formula (6), the formula (7), the formula (8) and the formula (9), the transmittance, the reflectance and the absorption are obtained, the transmittance is described by formula (10), the reflectance is described by formula (11), and the absorption is described by formula (12): (10); R = |r| 2 (11); A = 1-T-R (12), wherein T is the transmittance, η1 is the wave impedance of interface I, η2 is the wave impedance of interface II, t is the transmission coefficient, R is the reflectance, r is the reflection coefficient, and A is the absorption.

[0012] In some embodiments, the material of the second defect structure is alumina, and the thickness of the second defect structure is 10 μm-20 μm;

[0013] The permittivity ε of the alumina is 9.5 VO2 Described by formula (3): wherein ε∞ = 5.57 x 10 13 s -1 , and ε∞ is the permittivity at infinite frequency,

[0014] σ 0＝ 3 x 10 5 S / m, ω ρ (σ0) = 1.4 x 10 15 rad / s, conductivity σ VO2 Controlled by the method of applying thermal stimulation or electrical stimulation, and as σ VO2 increases, VO2 changes from an insulator to a metal at 68℃;

[0015] At 30℃, σ VO2 is 10 S / m; at 90℃, σ VO2 is 200000 S / m.

[0016] In some embodiments, the material of the intermediate layer is at least one of a quartz material and a first optical material;

[0017] The relative permittivity of the first optical material is 3-15;

[0018] The thickness d2 of the intermediate layer formed by the first optical material satisfies the formula n1d1=n2d2, wherein d1=15μm, n1=√4.4, and n2 is the refractive index of the intermediate layer formed by the first optical material.

[0019] In some embodiments, the material of the detection layer is a doped material, the doped material includes air and a substance to be detected, and the refractive index of the doped material is 1.3-1.6.

[0020] The incident wave is used to be incident at an angle perpendicular to the surface of the detection layer and to be emitted at an angle perpendicular to the surface of the detection layer.

[0021] In some embodiments, when the second defect structure is located on the side of the first defect structure close to the exit wave vector, the one-dimensional ternary structure photonic crystal biological detection sensor includes N first unit cells, the first defect structure, the second defect structure, and N second unit cells arranged in sequence along the direction from the incident wave vector to the exit wave vector, each of the first unit cells includes a single layer of the first graphene layer, a single layer of quartz, and a single layer of the second graphene layer, the first defect structure is a single layer of the detection layer, and the second defect structure is a single layer of molybdenum dioxide layer; wherein N≥3.

[0022] In some embodiments, the one-dimensional ternary structure photonic crystal biological detection sensor is a reflective sensor or a transmissive sensor, when the one-dimensional ternary structure photonic crystal biological detection sensor is the reflective sensor, the working frequency of the reflective sensor at 90℃ is 4.7THz-5.2THz, the sensitivity is 28.2μm / RIU (2.43THz / RIU), the quality factor value is 50.23, and the characteristic value is 23.85RIU -1 ; when the one-dimensional ternary structure photonic crystal biological detection sensor is the transmissive sensor, the working frequency of the transmissive sensor at 30℃ is 8.9THz-10.1THz, the sensitivity is 6.36μm / RIU (2.04THz / RIU), the quality factor value is 72.42, and the characteristic value is 14.99RIU -1 .

[0023] The chemical potential of the first graphene layer is 0.9eV, and the chemical potential of the second graphene layer is 1.0eV.

[0024] The dielectric constant of the quartz material of the quartz layer is 4.4, the thickness of the quartz layer is 15μm, and the magnetic permeability of the quartz layer is 1.

[0025] and / or, the thickness of the single-layer graphene layer is 0.35 nm, the thickness of the single-layer quartz layer is 0.35 nm, the thickness of the single-layer vanadium dioxide layer is 10 μm, the thickness of the single-layer detection layer is 20 μm, N = 3, and the incident angle is 0°.

[0026] In some embodiments, when the second defect structure is located on the side of all the unit cells away from the incident wave vector, the one-dimensional ternary structure photonic crystal biosensor comprises, in sequence along the direction from the incident wave vector to the emergent wave vector, N unit cells, the first defect structure, N unit cells, and the second defect structure, each of the unit cells comprises a single-layer first graphene layer, a quartz layer, and a single-layer second graphene layer, the first defect structure is a single-layer detection layer, and the second defect structure is a single-layer vanadium dioxide layer; and N ≥ 3.

[0027] In some embodiments, the one-dimensional ternary structure photonic crystal biosensor is a reflective sensor or a transmissive sensor, when the one-dimensional ternary structure photonic crystal biosensor is the reflective sensor, the working frequency of the reflective sensor at 90°C is 4.7 THz-5.1 THz, the sensitivity is 21.38 μm / RIU (1.87 THz / RIU), the quality factor value is 127.07, and the characteristic value is 46.13 RIU -1 ; when the one-dimensional ternary structure photonic crystal biosensor is the transmissive sensor, the working frequency of the transmissive sensor at 30°C is 9.3 THz-10.1 THz, the sensitivity is 7.25 μm / RIU (2.20 THz / RIU), the quality factor value is 69.79, and the characteristic value is 16.34 RIU -1 .

[0028] and / or, the chemical potential of the first graphene layer is 0.9 eV, and the chemical potential of the second graphene layer is 1.0 eV.

[0029] and / or, the dielectric constant of the quartz material of the quartz layer is 4.4, the thickness of the quartz layer can be 15 μm, and the magnetic permeability of the quartz layer is 1.

[0030] and / or, the thickness of the single-layer graphene layer is 0.35 nm, the thickness of the single-layer quartz layer is 0.35 nm, the thickness of the single-layer vanadium dioxide layer is 10 μm, the thickness of the single-layer detection layer is 20 μm, N = 3, and the incident angle is 0°.

[0031] In a second aspect, the application provides a biosensing system, comprising: a to-be-detected biological object, which is detected by the one-dimensional ternary structure photonic crystal biosensor as described above.

[0032] Compared with the prior art, the technical effects achieved by this application include:

[0033] This application provides a one-dimensional ternary photonic crystal biosensor. It incorporates vanadium dioxide into a one-dimensional graphene ternary photonic crystal structure. This allows for the use of multilayer graphene stacking, rather than simply increasing the chemical potential of a single layer of graphene, to achieve a larger bandgap. This reduces the number of periodic layers required for the same bandwidth and lowers costs. Furthermore, the ternary structure has a larger bandgap than existing binary structures, enabling refractive index sensing across the entire photonic bandgap with excellent transmission performance. This improves the sensor's detection range and enhances its fault tolerance. By introducing the phase-change material vanadium dioxide, it can achieve various sensing effects such as transmission and reflection at different temperatures, reducing the sensor's environmental requirements. Compared to existing binary photonic crystal sensors that cannot achieve sensing effects across different bandgap levels, this sensor offers more functions and wider application scenarios, and can achieve different types of sensing effects at different temperatures, demonstrating practical application and high efficiency. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of a one-dimensional ternary photonic crystal biosensor provided in an embodiment of this application;

[0036] Figure 2 This is a schematic diagram of another one-dimensional ternary structure photonic crystal biosensor provided in the embodiments of this application;

[0037] Figure 3 This is a schematic diagram of electromagnetic field propagation under TM polarization inside a one-dimensional ternary structure photonic crystal biosensor provided in an embodiment of this application;

[0038] Figure 4 yes Figure 1 The working effect of a one-dimensional ternary structure photonic crystal biosensor at 90℃;

[0039] Figure 5 yes Figure 1 The working effect of a one-dimensional ternary structure photonic crystal biosensor at 30℃;

[0040] Figure 6is Figure 2 Working effect of the one-dimensional ternary structure photonic crystal biosensor at 30 DEG C.

[0041] Figure 7 is Figure 2 Working effect of the one-dimensional ternary structure photonic crystal biosensor at 30 DEG C. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0043] In the present application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. Wherein, A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0044] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one" or similar expressions refer to any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c or a-b-c, wherein a, b and c can be single or multiple.

[0045] It should be understood that in various embodiments of the present application, the size of the serial number of each process does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0046] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0047] The weight of the related components mentioned in the embodiment specification of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component. Therefore, as long as the content of the related components in the embodiment specification of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the embodiment specification of the present application. Specifically, the mass in the embodiment specification of the present application can be μg, mg, g, kg, etc. well-known mass units.

[0048] The terms "first", "second", and the like are only used for descriptive purposes, to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the present application, the first XX can also be referred to as the second XX, and similarly, the second XX can also be referred to as the first XX. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features.

[0049] The following explains some terms in the present application to help those skilled in the art better understand.

[0050] 1. Dispersion material:

[0051] Dispersion is a property of the material itself, which in the present application is specifically manifested as the change of the dielectric constant of the material with frequency.

[0052] 2. Anisotropic material:

[0053] Anisotropy refers to the change of the properties of the material with direction, which in the present application is specifically manifested as the change of the dielectric constant of the material with direction.

[0054] 3. Graphene three-dimensional photonic crystal (GTPC):

[0055] GTPC refers to a periodic stacking after embedding a layer of dielectric between two layers of graphene, which combines the excellent photoelectric properties of graphene and the photon control ability of three-dimensional photonic crystal.

[0056] 4. Photonic band gap (PBG):

[0057] PBG is formed by the periodic arrangement of photonic crystals, and within the frequency range of the forbidden band, photons cannot propagate.

[0058] 5. Defect mode:

[0059] After adding other materials to the periodic photonic crystal, a frequency interval that allows photons to pass through is formed within the photonic band gap, which is shown as a sharp peak in the frequency-transmission characteristic diagram.

[0060] 6、Transverse Electric wave (TE):

[0061] TE wave refers to a wave with a magnetic field component and no electric field component in the direction of propagation.

[0062] 7、Transverse Magnetic wave (TM):

[0063] TM wave refers to a wave with an electric field component and no magnetic field component in the direction of propagation.

[0064] 8、Transverse Electromagnetic wave (TEM):

[0065] TEM wave refers to a wave with neither an electric field component nor a magnetic field component in the direction of propagation.

[0066] 9、K in and K out :

[0067] Wave vector (K) is a vector describing the direction of electromagnetic wave propagation and spatial periodicity. Among them, incident wave vector (K in ) refers to the wave vector of incident light wave. Outgoing wave vector (K out ) refers to the wave vector of outgoing light wave after being modulated by the sensor structure, which reflects the propagation characteristics of electromagnetic wave after penetrating or reflecting the biological sample to be detected.

[0068] 10、RIU:

[0069] Refractive index is essentially a dimensionless physical quantity (the ratio of the propagation speed of light in vacuum to the propagation speed in medium), that is, it has no unit itself, but in practical applications, for the convenience of expression, the order of magnitude or the change of the value of the refractive index is often referred to as "refractive index unit (RIU)".

[0070] 11、Terahertz wave:

[0071] Terahertz wave refers to electromagnetic wave with a frequency range of 0.1 THz-10 THz and a wavelength of about 3 mm-30 μm, which is between microwave and infrared light.

[0072] The above is a brief introduction to some individual terms involved in the embodiments of the present application, which will not be repeated hereinafter.

[0073] With the development of science and technology, a large number of in-depth researches have been carried out on optical materials. With the increasing use of optical materials, many optical devices with broad application prospects and novel functions, such as absorbers (the core function is to absorb a specific form of energy, such as light, heat, sound waves or electromagnetic waves, and convert it into other forms or prevent it from being reflected, propagated), reflectors (the core function is to reflect a specific form of energy, such as light, electromagnetic waves or sound waves, according to certain rules, changing its propagation direction), sensors (the core function is to detect physical quantities in the environment, such as temperature, humidity, light intensity, pressure or chemical quantities, and convert them into processable electrical signals or other signals for monitoring, control, analysis), etc. have emerged.

[0074] Among the many optical materials at present, graphene and phase change materials have anisotropy and other properties, which have been proved to be well applied in optical devices.

[0075] The optical properties of graphene can be represented by the following formula (1):

[0076]

[0077] In formula (1), ω is the angular frequency, μ c is the chemical potential of graphene, Γ = 1 THz is the scattering rate, T is the Kelvin temperature, e is the charge of an electron, is the reduced Planck constant, wherein the Planck constant h = 6.62607015 x 10 - 34 J·s, k B = 1.380649 x 10 -23 J / K, and is the Boltzmann constant, j is the imaginary unit, ε g is the relative permittivity of graphene, ε g，t is the permittivity component of graphene in the x direction and the y direction, ε g,⊥ is the permittivity component of graphene in the z direction, σ intra is the intraband conductivity of graphene, σ inter is the interband conductivity of graphene, ε0 is the permittivity of graphene, σ g is the conductivity of graphene, and α is the thickness of graphene. It should be noted that the x direction and the y direction are perpendicular to the thickness direction of graphene, the z direction is parallel to the thickness direction of graphene, the x direction is perpendicular to the y direction, and the x direction and the y direction are both perpendicular to the z direction.

[0078] Graphene is a two-dimensional honeycomb lattice structure tightly packed by single-layer carbon atoms, has unique electrical, mechanical and thermal properties, and the electron mobility at room temperature can be as high as 15000 cm 2(V·s) and so on, and graphene has adjustable optical properties μ c The dielectric constant of graphene can be changed significantly with the change of μ c Therefore, the photonic crystal with wide PBG can be prepared by using this property, and the photonic crystal with wide PBG also has strong reflection, transmission and other functions for light waves.

[0079] The optical properties (dielectric constant ε VO2 ) of the phase change material, for example, vanadium dioxide (VO2), can be represented by the following formula (2):

[0080] In formula (2), ε ∞ = 9 is the dielectric constant at infinite frequency, ω ρ (σ VO2 ) is the plasma frequency, γ = 5.75 × 10 13 s -1 , and is the damping frequency, ω is the angular frequency, j is the imaginary unit, σ VO2 is the conductivity of VO2, σ0 = 3 × 10 5 S / m, and is the limiting conductivity, ω p (σ0) = 1.4 × 10 15 rad / s, and is the plasma frequency under the limiting temperature condition,

[0081] VO2 is an anisotropic material, and the dielectric constant ε VO2 of VO2 changes sharply at the critical temperature of 68℃.

[0082] According to the above properties, graphene and VO2 can be combined to prepare optical devices that can work in different temperature environments, specifically sensors, and the sensors can also have two different working modes at different temperatures.

[0083] Related technologies have provided some optical devices combining graphene and VO2. For example, the article "Tunable And Multifunctional Terahertz Devices Based On One-Dimensional Anisotropic Photonic Crystals Containing Graphene And Phase-Change Material" mentions a photonic device combining graphene and VO2. However, the structure of this photonic device requires maximizing the chemical potential of graphene, making it difficult to realize in practical research and applications. Another example is the article "Tunable Electromagnetically Induced Transparency-Like In Graphene Metasurfaces And Its Application As ARefractive Index Sensor," which also mentions a photonic device combining graphene and VO2. However, the defect mode formed by this photonic device structure is dual-mode, which places extremely high demands on the accuracy of the detection equipment, making it difficult to realize in practical research and applications as well.

[0084] In summary, existing sensors containing graphene and VO2 are almost entirely binary structures. Under the same chemical potential conditions, the band gap of binary structures is very small, resulting in a small detection range and low detection efficiency. Moreover, the operating frequency of existing sensors containing graphene and VO2 is relatively fixed, making it impossible to achieve different sensing effects at different frequency bands or at different temperatures, thus severely limiting their application scenarios. Furthermore, existing sensors containing graphene and VO2 are inefficient and typically only have one good operating parameter, while the other parameters are poor, resulting in uneven performance that fails to meet practical needs.

[0085] It should be noted that the binary and ternary structures of sensors containing graphene and VO2 can be distinguished mainly by the number and composition differences of the core functional layers that make up the sensor. Specifically, a binary structure can be composed of graphene plus one key material, while a ternary structure can be composed of graphene plus two different key materials.

[0086] Based on the above, this application provides a one-dimensional ternary structure photonic crystal biosensor, which includes: along the incident wave vector (K... in ) to the outgoing wave vector (K out) direction, and sequentially arranged with at least three unit cells, a first defect structure, at least three unit cells, the number of unit cells on both sides of the first defect structure is the same, and each unit cell sequentially arranged with a single layer of first graphene layer, a single layer of intermediate layer and a single layer of second graphene layer; a first defect structure includes a single layer of detection layer, and any two adjacent structures contact each other.

[0087] The one-dimensional ternary structure photonic crystal biological detection sensor further includes a second defect structure, which is located on the side of the first defect structure close to the Kout direction, or the second defect structure is located on the side of all unit cells away from the Kin.

[0088] In the one-dimensional ternary structure photonic crystal biological detection sensor, there are a total of 2N unit cells, wherein N is a positive integer greater than or equal to 3, and the 2N unit cells are symmetrically distributed on both sides of the first defect structure. For example, in the case of arranging 3 unit cells on both sides of the defect structure, the one-dimensional ternary structure photonic crystal biological detection sensor contains a total of 6 unit cells; or in the case of arranging 4 unit cells on both sides of the defect structure, the one-dimensional ternary structure photonic crystal biological detection sensor contains a total of 8 unit cells; in the case of arranging 5 unit cells on both sides of the defect structure, the one-dimensional ternary structure photonic crystal biological detection sensor contains a total of 10 unit cells, and the rest is similar, which will not be introduced here.

[0089] It should be noted that in each unit cell, the single layer of first graphene layer, the single layer of intermediate layer and the single layer of second graphene layer arranged along the K in The single layer of first graphene layer, the single layer of intermediate layer and the single layer of second graphene layer arranged along the K

[0090] In application, the incident wave vector (K in ) refers to the wave vector of the incident light wave, which is 2πxf / c in the embodiment.

[0091] The materials of the first graphene layer (Graphene1) and the second graphene layer (Graphene2) have different chemical potentials, which can be realized by an external bias voltage method. For example, the chemical potentials of Graphene1 and Graphene2 can be 0.1eV-1eV, and there is a difference between them to ensure the difference in their dielectric constants, that is, according to formula (1), the materials of Graphene1 and Graphene2 have different dielectric constants.

[0092] In this way, independent control of terahertz can be realized, combined with the phase change characteristics of VO2 and the periodic structure of photonic crystal, to finally realize high-sensitivity detection of biomolecules by the one-dimensional ternary structure photonic crystal terahertz biological sensor based on graphene and phase change material (VO2).

[0093] In an application, the material of the detecting layer can be a doped material, which can be mixed with air and the substance to be detected. The refractive index of the doped material can be slightly greater than the refractive index of air. For example, the refractive index of the doped material can be 1.3-1.6. In this way, the interface reflectivity with air is moderate, which can form effective light-substance interaction and will not significantly change the band gap position of the photonic crystal, and good characteristics are maintained.

[0094] In addition, the incident wave can be incident at an angle perpendicular to the surface of the detecting layer and exit along an angle perpendicular to the surface of the detecting layer. In this way, on the one hand, when the terahertz wave is vertically incident, the electric field vector is parallel to the interface of the detecting layer, which can maximize the excitation of the Bragg scattering effect of the photonic crystal; on the other hand, by simplifying the optical path and reducing the angle-dependent loss, the efficient interaction of the terahertz wave and the detecting layer can be ensured, and the problems of polarization sensitivity or mode coupling caused by oblique incidence can be reduced.

[0095] For example, the material of the detecting layer can be polytetrafluoroethylene (PTFE) or the like.

[0096] In this way, the principle of the one-dimensional ternary structure photonic crystal biological detection sensor in the embodiment is that the defect mode effect in the forbidden band can be obtained by adding a detecting layer in the periodic photonic crystal. Specifically, the initial refractive index of the detecting layer is a fixed value. Due to the change of the concentration of biological molecules, the initial refractive index of the detecting layer changes, which causes the directional shift of the defect mode position. According to the shift amount of the defect mode position, the change of the concentration of biological molecules can be calculated to perform detection.

[0097] In an application, the material of the intermediate layer can be quartz material or a first optical material with a dielectric constant similar to that of quartz.

[0098] In the case of the intermediate layer being a quartz layer, the quartz layer can effectively isolate the adjacent first graphene layer and the second graphene layer as a high-insulation medium (large band gap, low conductivity) layer, ensuring that each graphene layer can independently regulate its Fermi level through an applied voltage, thereby regulating the surface plasmon resonance frequency, providing a basis for precise tuning of terahertz waves; at the same time, the quartz material has a stable and moderate refractive index in the terahertz wave band, which can cooperate with the first graphene layer, the second graphene layer and the VO2 layer to construct a reasonable periodic structure, so that the terahertz wave forms a strong resonance in the double target wave band, thereby enhancing the sensitivity of the biological molecule adsorption; in addition, the quartz material has low loss (small dielectric loss tangent) in the terahertz wave band, which can reduce the additional loss caused by near-field coupling between the first graphene layer and the second graphene layer, and reduce the interface reaction that may be caused by the direct contact of graphene and VO2; in addition, the quartz material has strong chemical stability and high mechanical strength, which can protect the graphene layer from being eroded by the biological sensing environment and maintain long-term stability.

[0099] In the case of the intermediate layer being a first optical material with a dielectric constant similar to that of quartz, the relative dielectric constant of the first optical material can be 3-15, for example, the relative dielectric constant of silicon dioxide (SiO2) is 3.8-4.3, the relative dielectric constant of boron nitride (BN) is 7.1, the relative dielectric constant of aluminum oxide (Al2O3) is 9.34-11.54, and the relative dielectric constant of silicon (Si) is 14.4.

[0100] On the basis of the above, the thickness d2 of the intermediate layer composed of the first optical material will be reduced to a certain extent compared with the thickness of the intermediate layer composed of quartz. Specifically, the thickness of the intermediate layer composed of the first optical material will be reduced with the increase of the dielectric constant, which can be referred to as the optical thickness formula n1d1=n2d2. In this embodiment, d1=15μm, n1=√4.4 (i.e. the square root of 4.4), and n2 is the refractive index of the intermediate layer composed of the first optical material. Similarly, the thickness of the intermediate layer composed of each material can be obtained.

[0101] It should be noted that the parameter affecting the properties of the graphene layer is mainly the chemical potential, so any thickness in practical application can be taken; at the same time, the thickness of the detection layer can be similar to that of the intermediate layer.

[0102] Therefore, intermediate layers of different materials and thicknesses can be obtained, so that the structure and performance of the one-dimensional ternary structure photonic crystal biological detection sensor can be more.

[0103] In application, the thickness of the phase change layer can be 10μm-20μm.

[0104] The phase change layer can be made of materials such as VO2. When the phase change layer is VO2, one-dimensional VO2 is a phase change material exhibiting abrupt changes in refractive index. The phase change temperature of VO2 is approximately 68°C, meaning it is in an insulating phase at room temperature (e.g., around 25°C), but rapidly transforms into a metallic phase when heated above 68°C. The dielectric constant ε of VO2... VO2 It can be described using the following formula (3): In formula (3), ε ∞ =5.57×10 13 s -1 , σ 0＝ 3×10 5 S / m, ω ρ (σ0)=1.4×10 15 rad / s, conductivity σ VO2 It can be controlled by applying thermal or electrical stimulation, and with σ VO2 With the increase of VO2, VO2 changes from an insulator to a metal at 68°C.

[0105] It should be noted that, without considering the specific values ​​of each parameter, formula (3) can be regarded as the same as formula (2), except that formula (3) is specifically used in this embodiment.

[0106] In this embodiment, when the selected temperature is 30°C, the corresponding σ VO2 It can be 10S / m; when the selected temperature is 90℃, the corresponding σ VO2 It can be 200,000 S / m.

[0107] Therefore, this embodiment realizes the design of a one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and phase change material (VO2). It can utilize the unique sensitivity of terahertz waves to the structure and interaction of biomolecules, and achieve accurate identification and quantitative analysis of target biological substances through the synergistic analysis of terahertz signals in two different bands.

[0108] In this embodiment, the transmission process of the one-dimensional ternary photonic crystal terahertz biosensor based on graphene and VO2 is typically analyzed using the transfer matrix method. The transfer matrix method can describe the physical relationship between the outgoing and incoming waves in matrix form. The dispersion relation of the photon transmission process in the one-dimensional ternary photonic crystal terahertz biosensor based on graphene and VO2 can be described by the following formulas (4) and (5): TE wave polarization: TM wave polarization: In formulas (4) and (5), k x Let k be the component of the wave in the x-direction. zFor the component of the wave in the z direction, k0=2π / f is the initial wave vector, ε1is the dielectric constant in the x direction, μ1is the magnetic permeability in the x direction, and ε3is the dielectric constant in the z direction.

[0109] According to the dispersion relations of formulas (4) and (5), the electromagnetic relationship between the incident wave and the outgoing wave under TE polarization and TM polarization in the transmission process of the wave in the single-layer material can be expressed in matrix form and described by the following formulas (6) and (7):

[0110] In formulas (6) and (7), k z is the wave vector, d is the thickness of the single-layer medium, E1 y is the y-direction electric field at the position of the dielectric material 1 under TE polarization, H1 x is the x-direction magnetic field at the position of the dielectric material 1 under TE polarization, E2 y is the y-direction electric field at the position of the dielectric material 2 under TE polarization, H2 x is the x-direction magnetic field at the position of the dielectric material 2 under TE polarization; H1 y is the y-direction magnetic field at the position of the dielectric material 1 under TM polarization, E1 x is the x-direction electric field at the position of the dielectric material 1 under TM polarization, H2 y is the y-direction magnetic field at the position of the dielectric material 2 under TM polarization, E2 x is the x-direction electric field at the position of the dielectric material 2 under TM polarization, H is the wave impedance (H is related to the optical properties of the material itself and the incident angle, in the present embodiment, the incident angle is constant, and H can be described without special description), and η is a process parameter related to the polarization mode and the material characteristics.

[0111] Specifically, η TE is the process parameter under TE polarization, and η TM is the process parameter under TM polarization, which are described by the following formulas (8) and (9): is: In formulas (8) and (9), μ = the relative magnetic permeability of the medium × μ0, μ0 = 4π × 10 -7 N / A, ε0 = 8.85 × 10 -12 (F / m) is the vacuum dielectric constant, and ε1is the dielectric constant of the medium in the x direction.

[0112] According to the formula (4), the formula (5), the formula (6), the formula (7), the formula (8) and the formula (9), the transmittance, the reflectance and the absorption can be obtained respectively, the transmittance is described by the following formula (10), the reflectance is described by the following formula (11), and the absorption is described by the following formula (12): R = |r| 2 (11); A = 1-T-R (12). In the formula (8) and the formula (9), T is the transmittance, η1 is the wave impedance of the interface I (specifically, the left side of the interface I), η2 is the wave impedance of the interface II (specifically, the right side of the interface II), t is the transmission coefficient, R is the reflectance, r is the reflection coefficient, and A is the absorption. It should be noted that the parameters in this part are variables.

[0113] Figure 3 The electromagnetic field propagation in the TM polarization case of the structure of the one-dimensional ternary photonic crystal terahertz biosensor based on graphene and VO2 is shown. Figure 3 E0 i is the initial electric field of the incident wave, H0 yi is the initial magnetic field of the incident wave, E1 it1 is the electric field of the transmitted wave at the interface I, H1 yit1 is the magnetic field of the transmitted wave at the interface I, E2 it2 is the electric field of the wave of the transmitted wave at the interface I after vector displacement, H2 yit2 is the magnetic field of the wave of the transmitted wave at the interface I after vector displacement, H3 yir1 is the magnetic field of the wave reflected by the interface II, H4 yir2 is the magnetic field of the wave after vector displacement after being reflected by the interface II, K4 r is the vector of the wave reflected by the interface I, H5 r is the magnetic field of the wave reflected by the interface I, E5 r is the electric field of the wave reflected by the interface I, E6 ir1 is the electric field of the wave reflected by the interface II, E7 ir2 is the electric field of the wave after vector displacement after being reflected by the interface II, E8 t is the electric field of the wave transmitted out of the interface II, H8 t is the magnetic field of the wave transmitted out of the interface II, θ0 is the angle between the incident wave and the normal, θ1 is the angle between the wave after transmitting through the interface I and the normal, and θ2 is the angle between the wave after transmitting through the interface II and the normal, all the angles in the application are 0°.

[0114] It should be noted that the present embodiment is the case of normal incidence, and therefore, it is not necessary to distinguish between TE polarization and TM polarization.

[0115] The one-dimensional ternary structure photonic crystal biological detection sensor provided in the embodiment of the present application combines VO2 on a one-dimensional graphene ternary photonic crystal structure. On the one hand, the one-dimensional ternary structure photonic crystal biological detection sensor can use the accumulation of multiple layers of graphene instead of simply increasing the chemical potential of a single layer of graphene to obtain a larger band gap, so that the required period layer number can be reduced under the same bandwidth, and the cost is lower. At the same time, the band gap of the ternary structure is larger than that of the existing binary structure, and the refractive index sensing function can be realized in the full-direction photonic band gap, and the transmission performance is good, which can improve the detection range of the sensor and improve the fault tolerance of the detection. On the other hand, by introducing the phase change material VO2, different sensing effects such as transmission and reflection can be realized at different temperatures, which reduces the requirements of the sensor on the working environment. Compared with the existing binary structure photonic crystal sensor which cannot complete the sensing effect in different band gaps, the one-dimensional ternary structure photonic crystal biological detection sensor has the advantages of more functions and more application scenarios, and can realize different types of sensing effects at different temperatures.

[0116] In summary, the one-dimensional ternary structure photonic crystal biological detection sensor in the embodiment can still realize high-sensitivity sensing effect at a similar working frequency when the structure changes, which improves the problem that the existing photonic crystal sensor cannot realize sensing effect in the case of structure change, and has practical application, high efficiency and other values.

[0117] The two specific structures and applications of the one-dimensional ternary structure photonic crystal biological detection sensor in the embodiment of the present application will be described in detail below with reference to Figure 1 and Figure 2 .

[0118] In some embodiments, as shown in Figure 1 , the one-dimensional ternary structure photonic crystal biological detection sensor provided in the embodiment of the present application comprises: N unit cells, a first defect structure, a second defect structure, N unit cells arranged in sequence along the direction from K in to K out , each unit cell comprises a single-layer first graphene layer 11, a single-layer quartz layer 12 and a single-layer second graphene layer 13, the first defect structure is a single-layer detection layer 21, the second defect structure is a single-layer VO2 layer 22, and N≥3.

[0119] Therefore, Figure 1The N unit cells are arranged on the left side of the single-layer detection layer 21, and the N unit cells are arranged on the right side of the single-layer VO2 layer 22, that is, the one-dimensional ternary photonic crystal biological detection sensor has a total of 2N unit cells, each of which has two different single-layer graphene layers and single-layer quartz layers 12, and the two different single-layer graphene layers and single-layer quartz layers 12 constitute a one-dimensional ternary photonic crystal unit. At the same time, the period of the unit cell 1 on the left side of the single-layer detection layer 21 and the unit cell 1 on the right side of the single-layer VO2 layer 22 are both set to N, and the detection layer 21 and the VO2 layer 22 composed of a phase change material are inserted in the middle part of the two, thereby completing the design of the one-dimensional ternary photonic crystal biological detection sensor.

[0120] It should be noted that, Figure 1 The ellipsis in the formula (1) represents other repeated unit cells not shown in the figure.

[0121] In the application, the chemical potential of the first graphene layer 11 can be set to 0.9 eV, and the chemical potential of the second graphene layer 13 can be set to 1.0 eV. Then, according to the formula (1), the first graphene layer 11 and the second graphene layer 13 have different dielectric constants.

[0122] The doping material of the detection layer 21 is mixed by air and the substance to be detected, and the refractive index of the doping material is slightly larger than that of air, which can be 1.30, 1.40, 1.50 or 1.60, etc. In addition, the incident wave energy is incident at an angle perpendicular to the surface of the detection layer 21, and is emitted along the angle perpendicular to the surface of the detection layer 21, that is, the normal incidence case.

[0123] The dielectric constant of the quartz material of the quartz layer 12 can be 4.4, the thickness of the quartz layer 12 can be 15 μm, and the magnetic permeability of the quartz layer 12 can be constant 1. Therefore, the quartz material can be considered as an isotropic material on the premise that the physical shape is not damaged.

[0124] Figure 1 The one-dimensional ternary photonic crystal terahertz biological sensor based on graphene and VO2 in the formula (1) can be applied as a reflective sensor, and the effect is as shown in Figure 4 , and, Figure 1 The one-dimensional ternary photonic crystal terahertz biological sensor based on graphene and VO2 in the formula (1) can also be applied as a transmissive sensor, and the effect is as shown in Figure 5 , and, Figure 4In the figure, the horizontal axis represents frequency (Frequency) in THz, and the vertical axis represents reflectivity (Reflection). n0 represents the refractive index of the detection layer material. The light blue curve represents a refractive index of 1.30 for the detection layer material, the green curve represents a refractive index of 1.33 for the detection layer material, the purple curve represents a refractive index of 1.36 for the detection layer material, the yellow curve represents a refractive index of 1.39 for the detection layer material, the orange curve represents a refractive index of 1.42 for the detection layer material, and the dark blue curve represents a refractive index of 1.45 for the detection layer material. Figure 5 In the figure, the horizontal axis represents frequency (Frequency) in THz, and the vertical axis represents transmission (Transmission). n0 represents the refractive index of the detection layer material. The light blue curve represents a refractive index of 1.30 for the detection layer material, the green curve represents a refractive index of 1.33 for the detection layer material, the purple curve represents a refractive index of 1.36 for the detection layer material, the yellow curve represents a refractive index of 1.39 for the detection layer material, the orange curve represents a refractive index of 1.42 for the detection layer material, and the dark blue curve represents a refractive index of 1.45 for the detection layer material.

[0125] wherein, Figure 4 The working effect of the graphene and VO2-based one-dimensional ternary structure photonic crystal terahertz biosensor at 90°C is shown in the figure. At this time, the sensor is a reflection-type sensor, and the working frequency can be 4.7 THz to 5.2 THz, within the first Bragg band gap (Gap1) of the photonic crystal. The sensitivity S of the reflection-type sensor can reach 28.2 μm / RIU (2.43 THz / RIU), the quality factor (Q) value can be 50.23, and the Figure of Merit (FOM) can be 23.85 RIU -1 .

[0126] It should be noted that the phase transition (critical) temperature of VO2 is 68°C, and the typical temperature selected here is 90°C. Below 68°C, VO2 shows an insulating state, and above 68°C, VO2 shows a metallic state.

[0127] In addition, above 90°C, the graphene and VO2-based one-dimensional ternary structure photonic crystal terahertz biosensor in the embodiment can realize a reflection-type refractive index sensor.

[0128] wherein, Figure 5The working effect of the one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 at 30℃ is a transmission type sensor, the working frequency of which can be 8.9THz-10.1THz, in the second Bragg band gap (Gap2), the sensitivity of the transmission type sensor can reach 6.36μm / RIU (2.04THz / RIU), the Q value can be 72.42, and the FOM value can be 14.99RIU -1 .

[0129] It should be noted that below 30℃, the one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 in this embodiment can realize a transmission type or a reflection type refractive index sensor.

[0130] Figure 1 The material parameters of the one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 in this embodiment can be set as: h1=0.35nm, h2=0.35nm, h3=10μm, h4=20μm, period N=3, and incident angle θ=0°.

[0131] It should be noted that in order to facilitate actual flexible use, the period N can be appropriately increased.

[0132] The above h1 is the thickness of the first graphene layer 11 and the thickness of the second graphene layer 13, h2 is the thickness of the single-layer quartz layer 12, h3 is the thickness of the single-layer VO2 layer 22, and h4 is the thickness of the single-layer detection layer 21.

[0133] Under the above parameter design, the sensing effect and working efficiency of the one-dimensional ternary structure photonic crystal terahertz biosensor are shown in Table 1.

[0134] Among them, the former (Gap1) is the sensing effect of the first band gap at 90℃ (reflection type), and the latter (Gap2) is the sensing effect of the second band gap at 30℃ (transmission type).

[0135] Table 1

[0136]

[0137]

[0138] As can be seen from Table 1, the sensitivity of the one-dimensional ternary structure photonic crystal terahertz biosensor can reach a maximum of 28.2um / RIU, the Q value can reach a maximum of 361.82, and the FOM value can reach a maximum of 63.33RIU -1 , which has very good performance.

[0139] The one-dimensional ternary structure photonic crystal biological detection sensor provided in the embodiment can realize different types of sensing effects at different temperatures, that is, can constitute a reflection type sensor and a transmission type sensor at different temperatures, reduces the requirement of the one-dimensional ternary structure photonic crystal biological detection sensor on the working environment, makes it have more functions, more application scenarios, and can realize different types of sensing effects at different temperatures; meanwhile, a larger band gap is obtained by using the stacking of multiple layers of graphene, so that the required period layer number is reduced at the same bandwidth, and the cost is relatively low; in addition, the ternary structure can realize the refractive index sensing function in the omnidirectional photonic band gap, and has good transmission performance, which can improve the detection range of the one-dimensional ternary structure photonic crystal biological detection sensor, and improve the fault tolerance of detection. In short, the one-dimensional ternary structure photonic crystal biological detection sensor in the embodiment has good comprehensive performance, which is beneficial to industrial production and application.

[0140] In some embodiments, as shown in the reference Figure 2 The one-dimensional ternary structure photonic crystal biological detection sensor provided in the embodiment includes: in the direction from Kin to Kout, N unit cells, a first defect structure, N unit cells, and a second defect structure are arranged in sequence, each unit cell includes a single-layer first graphene layer 11, a single-layer quartz layer 12, and a single-layer second graphene layer 13, the first defect structure is a single-layer detection layer 21, and the second defect structure is a single-layer VO2 layer 22.

[0141] Therefore, Figure 2 In the single-layer detection layer 21, N unit cells are arranged on the left side of the single-layer detection layer 21, and N unit cells are also arranged on the right side of the single-layer detection layer 21, that is, the one-dimensional ternary structure photonic crystal biological detection sensor has a total of 2N unit cells, and each unit cell has two different single-layer graphene layers and single-layer quartz layers 12, which constitute a one-dimensional ternary photonic crystal unit. At the same time, the period of the unit cell 1 located on the left and right sides of the single-layer detection layer 21 is set to N, and the detection layer 21 is inserted in the middle part of the two, and the VO2 layer 22 composed of a phase change material is inserted at the end, so that the design of the one-dimensional ternary structure photonic crystal biological detection sensor is completed.

[0142] It should be noted that Figure 2 The ellipsis in the formula represents other repeated unit cells not drawn in the figure.

[0143] In the application, the chemical potential of the first graphene layer 11 can be set to 0.9eV, and the chemical potential of the second graphene layer 13 can be set to 1.0eV, so that the first graphene layer 11 and the second graphene layer 13 have different dielectric constants according to formula (1).

[0144] The doping material of the detection layer 21 is mixed by air and the substance to be detected, and the refractive index of the doping material is slightly greater than that of air, which can be 1.30, 1.40, 1.50 or 1.60, etc. In addition, the incident wave energy is incident at an angle perpendicular to the surface of the detection layer 21, and is emitted along the angle perpendicular to the surface of the detection layer 21, that is, the normal incidence case.

[0145] The dielectric constant of the quartz material of the quartz layer 12 can be 4.4, the thickness of the quartz layer 12 can be 15 μm, and the magnetic permeability of the quartz layer 12 can be constant 1, so that the quartz material can be considered as an isotropic material on the premise that the physical shape is not damaged.

[0146] Figure 2 The one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 can be applied as a transmission type sensor, and the effect is as shown in Figure 6 , and, Figure 2 The one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 can also be applied as a reflection type sensor, and the effect is as shown in Figure 7 . In Figure 6 , the abscissa represents the frequency (Frequency) in terahertz (THz), and the ordinate represents the reflectivity (Reflection). n0 represents the refractive index of the detection layer material. The light blue curve represents the refractive index of the detection layer material being 1.30, the green curve represents the refractive index of the detection layer material being 1.33, the purple curve represents the refractive index of the detection layer material being 1.36, the yellow curve represents the refractive index of the detection layer material being 1.39, the orange curve represents the refractive index of the detection layer material being 1.42, and the dark blue curve represents the refractive index of the detection layer material being 1.45. In Figure 7 , the abscissa represents the frequency (Frequency) in THz, and the ordinate represents the transmission (Transmission). n0 represents the refractive index of the detection layer material. The light blue curve represents the refractive index of the detection layer material being 1.30, the green curve represents the refractive index of the detection layer material being 1.33, the purple curve represents the refractive index of the detection layer material being 1.36, the yellow curve represents the refractive index of the detection layer material being 1.39, the orange curve represents the refractive index of the detection layer material being 1.42, and the dark blue curve represents the refractive index of the detection layer material being 1.45.

[0147] , wherein, Figure 6For the working effect of the one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 at 90℃, the sensor is a reflective sensor, the working frequency can be 4.7THz-5.1THz, in the first Bragg band gap (Gap1) of the photonic crystal, the sensitivity S of the reflective sensor can reach 21.38μm / RIU (1.87THz / RIU), the Q value can be 127.07, and the FOM can be 46.13RIU -1 .

[0148] In addition, above 90℃, the one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 in the embodiment can realize a reflective refractive index sensor.

[0149] Among them, Figure 7 For the working effect of the one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 at room temperature, the sensor is a transmissive sensor, the working frequency can be 9.3THz-10.1THz, in the second Bragg band gap (Gap2) of the photonic crystal, the sensitivity of the transmissive sensor can reach 7.25μm / RIU (2.20THz / RIU), the Q value can be 69.79, and the FOM value can be 16.34RIU -1 .

[0150] It should be noted that below 30℃, the one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 in the embodiment can realize a transmissive refractive index sensor or a reflective refractive index sensor.

[0151] Figure 2 The material parameters of the one-dimensional ternary structure photonic crystal terahertz biosensor based on graphene and VO2 in the embodiment can be set as: h1=0.35nm, h2=0.35nm, h3=10μm, h4=20μm, period N=3, and incident angle θ=0°.

[0152] It should be noted that in order to facilitate actual flexible use, the period N can be appropriately increased.

[0153] The above h1 is the thickness of the first graphene 11 and the thickness of the second graphene 12, h2 is the thickness of the single-layer quartz layer 12, h3 is the thickness of the single-layer VO2 layer 22, and h4 is the thickness of the single-layer detection layer 21.

[0154] Under the above parameter design, the sensing effect and working efficiency of the one-dimensional ternary structure photonic crystal terahertz biosensor are shown in Table 2.

[0155] The former (Gap1) is the sensing effect (reflection type) of the first band gap at 90℃, and the latter (Gap2) is the sensing effect (transmission type) of the second band gap at 30℃.

[0156] Table 2

[0157]

[0158] As can be seen from Table 2, the sensitivity of the one-dimensional ternary structure photonic crystal terahertz biosensor can reach 21.38um / RIU at most, the Q value can reach 509.14 at most, and the FOM value can reach 116.58RIU at most, and the performance is very good. -1

[0159] The one-dimensional ternary structure photonic crystal biosensor provided in the embodiment can realize different types of sensing effects at different temperatures, that is, can constitute a transmission type sensor and a reflection type sensor at different temperatures, reduces the requirement of the one-dimensional ternary structure photonic crystal biosensor on the working environment, makes it have more functions, more application scenarios, and can realize different types of sensing effects at different temperatures; at the same time, a larger band gap is obtained by using the stacking of multiple layers of graphene, so that the required period number is reduced at the same bandwidth, and the cost is lower; moreover, the ternary structure can realize the refractive index sensing function in the omnidirectional photonic band gap, and has good transmission performance, can improve the detection range of the one-dimensional ternary structure photonic crystal biosensor, and improve the fault tolerance of detection. In general, the one-dimensional ternary structure photonic crystal biosensor in the embodiment has good comprehensive performance, and is beneficial to industrial production and application.

[0160] Table 3 is a table of maximum efficiency (specifically, maximum sensitivity, maximum Q value, and maximum FOM) obtained under the structure of Figure 1 and the structure transformation period (N=3-6) of Figure 2 in the embodiment of the application, and compared with mainstream literature in related technologies. Among them, the mainstream literature is article one “Enhancing Sensitivity To Ambient Refractive Index With Tunable Few-Layer Graphene / hBN Nanoribbons”, article two “A Graphene Based Tunable Terahertz Sensor With Double Fano Resonances”, and article three “Tunable Metamaterial-Induced Transparency”, and Figure 1 the structure of Figure 2 ​The one-dimensional ternary structure photonic crystal biosensors provided by the respective structures can all be used in the terahertz broadband range.

[0161] Table 3

[0162]

[0163] As can be seen from Table 3, in the embodiments of this application Figure 1 Structure and Figure 2 The one-dimensional ternary structure photonic crystal terahertz biosensors provided by the respective structures have higher working efficiency than sensors in related technologies, and their performance is excellent.

[0164] This section only introduces the content related to the invention point; the rest can be obtained by referring to relevant technologies, and will not be described in detail here.

[0165] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A one-dimensional ternary photonic crystal biosensor, characterized in that, In the direction from the incident wave vector to the exit wave vector, at least three unit cells, a first defect structure and at least three unit cells are arranged in sequence, the number of the unit cells on both sides of the first defect structure is the same, each of the unit cells has a first graphene layer, an intermediate layer and a second graphene layer arranged in sequence, and the first defect structure comprises a detection layer, and any two adjacent structures are in contact. The one-dimensional ternary structure photonic crystal biological detection sensor further comprises a second defect structure, and the second defect structure is located on the side of the first defect structure close to the exit wave vector, or the second defect structure is located on the side of all the unit cells away from the incident wave vector.

2. The one-dimensional ternary-structured photonic crystal biosensor according to claim 1, wherein, The transmission process of the one-dimensional ternary structure photonic crystal biological detection sensor is analyzed by using the transfer matrix method, and the dispersion relation is described by formula (4) and formula (5). TE wave polarization: k x 2 +k z 2 = k0 2 ε1μ1 (4); TM wave polarization: where kx x is the component of the wave in the x direction, k z is the component of the wave in the z direction, k0= 2π / f, and is the initial wave vector, ε1is the dielectric constant in the x direction, μ1is the magnetic permeability in the x direction, ε3is the dielectric constant in the z direction; the x direction is a direction perpendicular to the thickness direction of the first graphene layer, the z direction is a direction parallel to the thickness direction of the first graphene layer, and the x direction is perpendicular to the z direction; According to the formula (4) and the formula (5), the electromagnetic relationship between the incident wave and the exit wave under TE polarization and TM polarization in the transmission process of the wave in the single-layer material is represented by a matrix form, and is described by formula (6) and formula (7). wherein k z is the wave vector, d is the thickness of a single layer of medium, E1 y is the y-direction electric field at the location of medium material 1 under TE polarization, H1 x is the x-direction magnetic field at the location of medium material 1 under TE polarization, E2 y is the y-direction electric field at the location of medium material 2 under TE polarization, H2 x is the x-direction magnetic field at the location of medium material 2 under TE polarization; H1 y is the y-direction magnetic field at the location of medium material 1 under TM polarization, E1 x is the x-direction electric field at the location of medium material 1 under TM polarization, H2 y is the y-direction magnetic field at the location of medium material 2 under TM polarization, E2 x is the x-direction electric field at the location of medium material 2 under TM polarization, H is the wave impedance, η is a process parameter, and is related to the polarization mode and material characteristics, η TE is the process parameter under TE polarization, described by equation (8): η TM is the process parameter under TM polarization, described by equation (9): wherein μ = relative magnetic permeability of medium x μ0, μ0 = 4π x 10 - 7 N / A, ε0 = 8.85 x 10 -12 (F / m) is the vacuum permittivity, ε1 is the permittivity of the medium in the x-direction; the y-direction is perpendicular to the thickness direction of the first graphene layer, and the y-direction is perpendicular to the x-direction and the z-direction, respectively; The transmittance, reflectance and absorptance are obtained according to the formula (4), the formula (5), the formula (6), the formula (7), the formula (8) and the formula (9), and are described by the formula (10) for the transmittance, the formula (11) for the reflectance and the formula (12) for the absorptance: (10); R = |r| 2 (11); A = 1 - T - R (12), wherein T is the transmittance, η1 is the wave impedance of the interface I, η2 is the wave impedance of the interface II, t is the transmission coefficient, R is the reflectance, r is the reflection coefficient, and A is the absorptance.

3. The one-dimensional ternary-structured photonic crystal biosensor according to claim 1 or 2, characterized in that, The material of the second defect structure is alumina, and the thickness of the second defect structure is 10-20 μm. The dielectric constant ε of the said dioxides VO2 Equation (3) is used to describe: wherein ε∞= 5.57 x 10 13 s -1 and ε∞ is the dielectric constant at infinite frequency, σ 0＝ 3 x 10 5 S / m, ω ρ (σ0) = 1.4 x 10 15 rad / s, conductivity σ VO2 Controlled by the method of applying thermal or electrical stimulation, and as σ VO2 increases, VO2 changes from an insulator to a metal at 68°C; at 30°C, σ VO2 is 10 S / m; at 90°C, σ VO2 is 200 000 S / m.​​ 4. The one-dimensional ternary-structured photonic crystal biosensor according to claim 1 or 2, characterized in that, The material of the intermediate layer is at least one of quartz material and first optical material. The relative dielectric constant of the first optical material is 3-15. The thickness d2 of the intermediate layer formed by the first optical material satisfies the formula n1d1=n2d2, wherein d1=15 μm, n1=√4.4, and n2 is the refractive index of the intermediate layer formed by the first optical material.

5. The one-dimensional ternary-structured photonic crystal biosensor according to claim 1 or 2, wherein, The material of the detection layer is a doped material, the doped material includes air and a substance to be detected, and the refractive index of the doped material is 1.3-1.

6. The incident wave is used to be incident at an angle perpendicular to the surface of the detection layer and to be emitted along the angle perpendicular to the surface of the detection layer.

6. The one-dimensional ternary-structured photonic crystal biosensor according to claim 1 or 2, wherein, In the case that the second defect structure is located on the side of the first defect structure close to the exit wave vector, the one-dimensional ternary structure photonic crystal biological detection sensor comprises N unit cells, the first defect structure, the second defect structure and N unit cells arranged in sequence in the direction from the incident wave vector to the exit wave vector, each of the unit cells comprises a single-layer first graphene layer, a single-layer quartz layer and a single-layer second graphene layer, the first defect structure is a single-layer detection layer, and the second defect structure is a single-layer alumina layer; wherein N≥3.

7. The one-dimensional ternary-structured photonic crystal biosensor according to claim 6, wherein, The one-dimensional ternary structure photonic crystal biological detection sensor is a reflection type sensor or a transmission type sensor, in the case of the one-dimensional ternary structure photonic crystal biological detection sensor being a reflection type sensor, the working frequency of the reflection type sensor at 90 DEG C is 4.7 THz-5.2 THz, the sensitivity is 28.2 mu m / RIU (2.43 THz / RIU), the quality factor value is 50.23, and the characteristic value is 23.85 RIU -1 ; in the case of the one-dimensional ternary structure photonic crystal biological detection sensor being a transmission type sensor, the working frequency of the transmission type sensor at 30 DEG C is 8.9 THz-10.1 THz, the sensitivity is 6.36 mu m / RIU (2.04 THz / RIU), the quality factor value is 72.42, and the characteristic value is 14.99 RIU -1 ; The chemical potential of the first graphene layer is 0.9 eV, and the chemical potential of the second graphene layer is 1.0 eV. The dielectric constant of the quartz material of the quartz layer is 4.4, the thickness of the quartz layer is 15 μm, and the magnetic permeability of the quartz layer is 1. The thickness of the single-layer graphene layer is 0.35 nm, the thickness of the single-layer quartz layer is 0.35 nm, the thickness of the single-layer alumina layer is 10 μm, the thickness of the single-layer detection layer is 20 μm, N=3, and the incident angle is 0°.

8. The one-dimensional ternary-structured photonic crystal biosensor according to claim 1 or 2, wherein, In the case that the second defect structure is located on the side of all the unit cells away from the incident wave vector, the one-dimensional ternary structure photonic crystal biological detection sensor comprises, in sequence along the direction from the incident wave vector to the emergent wave vector, N unit cells, the first defect structure, N unit cells, and the second defect structure, each of the unit cells comprises a single layer of the first graphene layer, a quartz layer, and a single layer of the second graphene layer, the first defect structure is a single layer of the detection layer, and the second defect structure is a single layer of a vanadium dioxide layer; and N is greater than or equal to 3.

9. The one-dimensional ternary-structured photonic crystal biosensor according to claim 8, wherein, The one-dimensional ternary structure photonic crystal biological detection sensor is a reflection type sensor or a transmission type sensor, in the case of the one-dimensional ternary structure photonic crystal biological detection sensor being a reflection type sensor, the working frequency of the reflection type sensor at 90 DEG C is 4.7 THz-5.1 THz, the sensitivity is 21.38 mu m / RIU (1.87 THz / RIU), the quality factor value is 127.07, and the characteristic value is 46.13 RIU -1 ; in the case of the one-dimensional ternary structure photonic crystal biological detection sensor being a transmission type sensor, the working frequency of the transmission type sensor at 30 DEG C is 9.3 THz-10.1 THz, the sensitivity is 7.25 mu m / RIU (2.20 THz / RIU), the quality factor value is 69.79, and the characteristic value is 16.34 RIU -1 ; And / or, the chemical potential of the first graphene layer is 0.9 eV, and the chemical potential of the second graphene layer is 1.0 eV. And / or, the dielectric constant of the quartz material of the quartz layer is 4.4, the thickness of the quartz layer can be 15 μm, and the magnetic permeability of the quartz layer is 1. And / or, the thickness of the single layer of the graphene layer is 0.35 nm, the thickness of the single layer of the quartz layer is 0.35 nm, the thickness of the single layer of the vanadium dioxide layer is 10 μm, the thickness of the single layer of the detection layer is 20 μm, N is 3, and the incident angle is 0°.

10. A biological detection system characterized by, Comprise: A biological to be detected, wherein the biological to be detected is detected by using the one-dimensional ternary structure photonic crystal biological detection sensor according to any one of claims 1 to 9.

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