Angle-independent narrow-spectrum heat emitter design based on continuum bound state design

Abstract

The invention discloses an angle-independent narrow-spectrum thermal emitter design based on continuum bound state design, and relates to the technical field of engineering thermophysics. The plurality of dielectric cylinders are arranged on the metal substrate and are arranged in a regular hexagon shape; each dielectric cylinder comprises a low refractive index dielectric cylinder arranged on the metal substrate; and the high-refractive-index medium cylinder is arranged on the low-refractive-index medium cylinder. The method has the advantages that the structure is compatible with a traditional micro-nano structure processing technology, common conventional materials are adopted, and large-scale and large-batch preparation is achieved by matching a photoetching technology with a maskless laser direct writing technology.

Description

Technical Field

[0001] The invention relates to the technical field of engineering thermal physics, and in particular to a design of an angle-independent narrow-spectrum thermal emitter based on a continuum bound state design. Background Art

[0002] As a non-contact infrared gas detection technology, non-dispersive infrared (NDIR) technology mainly relies on the infrared absorption spectrum of the gas to detect the type and concentration of the gas. The basic principle is to rely on the energy attenuation of the infrared emitter before and after passing through the target gas to analyze and obtain the type and concentration of the target gas. Its essence is to detect the vibration or rotation frequency of the target gas molecules. Therefore, the Q value of the infrared emitter's outward emission spectrum and the degree of matching with the current gas are the key to improving the accuracy and sensitivity of the detector. Compared with the wide-spectrum light source, the thermal emitter based on metasurface design can better match the infrared absorption peak of the gas because it can achieve selective narrow-spectrum emission. The design requirements of the metasurface narrow-spectrum emitter mainly involve three factors: emissivity, Q value and angular dispersion. The emissivity value determines the energy selectively emitted by the thermal emitter under thermal equilibrium; the Q value affects the energy utilization efficiency of the device; and the degree of spatial angular dispersion affects the energy utilization efficiency and the complexity of the energy device system design. When designing a narrow-spectrum thermal emitter for energy devices, it is necessary to consider the influence of the three factors at the same time to obtain better performance.

[0003] However, so far, the narrow-spectrum selective emitters designed are usually difficult to take into account all three requirements. For example, the metasurfaces designed based on grating structures can only maintain narrow-spectrum emission in a small spatial angle range within the gas absorption characteristic peak range, resulting in low energy utilization efficiency. Or based on the Metal-Insulation-Metal structure, although it can achieve spatial angle-independent emission, the material loss between the two layers of metal leads to a low Q value, resulting in the gas signal of the required detector being submerged in the background signal and difficult to detect, reducing the overall detection accuracy of the system. The continuum bound state (BIC) is a non-radiative phenomenon on the light cone line. It has an extremely high Q value. When a specific perturbation is applied, it can be transformed into a continuum quasi-bound state (quasi-BIC, QBIC), which exists on both sides of the BIC. This mode is highly designable and can achieve perfect emission (emissivity = 1) while having extremely high Q value spectral line characteristics. Therefore, it provides a basis for designing narrow-spectrum thermal emission devices that are independent of spatial angles. Summary of the invention

[0004] In view of the above problems or problems existing in the prior art, the present invention is proposed.

[0005] Therefore, an object of the present invention is to provide an angle-independent narrow-spectrum thermal emitter design based on continuum bound state design, which can solve the problems mentioned in the background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: an angle-independent narrow-spectrum thermal emitter design based on a continuum bound state design, comprising a metal substrate; a plurality of dielectric cylinders, the plurality of dielectric cylinders being arranged on the metal substrate and in a regular hexagonal arrangement;

[0007] Each of the dielectric cylinders includes a low-refractive-index dielectric cylinder disposed on the metal substrate; and a high-refractive-index dielectric cylinder disposed on the low-refractive-index dielectric cylinder.

[0008] As a preferred solution of the angle-independent narrow-spectrum thermal emitter design based on continuum bound state design described in the present invention, the diameter of the low-refractive index medium cylinder is D, and the side length of the regular hexagonal arrangement of the plurality of medium cylinders is The height of the high refractive index medium cylinder is H1, and the height of the low refractive index medium cylinder is H2.

[0009] As a preferred scheme for the design of an angle-independent narrow-spectrum thermal emitter based on continuum bound state design described in the present invention, wherein: the metal substrate is selected from one of gold, silver, aluminum, and tungsten; the low-refractive-index medium cylinder is selected from one of silicon dioxide, magnesium fluoride, and zinc sulfide; the high-refractive-index medium cylinder is selected from one of amorphous silicon, germanium, and indium arsenide.

[0010] As a preferred solution for the design of the angle-independent narrow-spectrum thermal emitter based on continuum bound state design described in the present invention, the metal substrate is gold, the low refractive index medium cylinder is silicon dioxide, and the high refractive index medium cylinder is germanium with a refractive index of 4.0.

[0011] As a preferred scheme for the design of an angle-independent narrow-spectrum thermal emitter based on continuum bound state design described in the present invention, wherein: the thickness of the metal substrate is greater than 0.1 micron; the height H2 of the low refractive index medium cylinder is 0.31-0.44 micron, and the diameter D of the low refractive index medium cylinder is 0.85-1.2 micron; the height H1 of the high refractive index medium cylinder is 0.56-0.79 micron, and the diameter of the high refractive index medium cylinder is 0.85-1.2 micron.

[0012] As a preferred solution for the angle-independent narrow-spectrum thermal emitter design based on continuum bound state design described in the present invention, Mie resonance modes coupled by magnetic dipoles and electric quadrupoles are generated in the multiple dielectric cylinders.

[0013] As a preferred solution for the design of an angle-independent narrow-spectrum thermal emitter based on continuum bound state design described in the present invention, under transverse electric TE polarization, the emission peak wavelength of the angle-independent narrow-spectrum thermal emitter in the angle range of 0-89 degrees is offset by less than 1% relative to the 0-degree emission peak wavelength.

[0014] As a preferred solution for the design of the angle-independent narrow-spectrum thermal emitter based on continuum bound state design described in the present invention, the emissivity and emission Q value of the angle-independent narrow-spectrum thermal emitter are regulated by adjusting the height H2 of the low refractive index medium cylinder.

[0015] As a preferred scheme for the design of an angle-independent narrow-spectrum thermal emitter based on continuum bound state design described in the present invention, wherein: at 0 degree positive emission, the narrow-spectrum emission of the angle-independent narrow-spectrum thermal emitter has the same Q value under transverse electric TE polarization and transverse magnetic TM polarization, the Q value is greater than 600, and the narrow-spectrum emissivity is greater than 0.9.

[0016] As a preferred scheme for the design of an angle-independent narrow-spectrum thermal emitter based on continuum bound state design described in the present invention, the emission peak wavelength of the angle-independent narrow-spectrum thermal emitter is proportional to the structural proportional coefficient S, and the emission peak wavelength is within the 3-6 micron band.

[0017] Beneficial effects of the present invention: The angle-independent narrow-spectrum emitter used in the NDIR gas detection technology of the present invention can achieve a high Q value emission of 3-6 microns by scaling the size of the high and low refractive index medium cylinders on the metal reflective layer. Its emission peak is proportional to the proportional coefficient S of the structure, and can be flexibly adjusted to match the infrared absorption peaks of various gases.

[0018] Compared with the current MIM infrared emitter, whose positive emission Q value is limited to 10-20, this structure utilizes the theoretical design of continuum bound states and reduces the structural metal layer to achieve emission with a higher Q value (Q value can reach ), which can further improve the accuracy and sensitivity of NDIR gas detection.

[0019] Compared with the defects of most current metasurface narrow spectrum emitters that are difficult to simultaneously meet the performance requirements of spatial angle dispersion and high Q value, this structure uses the mode dominated by magnetic dipoles and the regular hexagonal arrangement. Under TE polarization, the emission peak wavelength hardly changes with the spatial angle. In the 0-89 angle range, the ratio of the emission peak wavelength offset to the 0-degree emission peak wavelength is less than 1%, thereby improving the utilization rate of effective radiation energy in space.

[0020] The structure of the present invention is compatible with traditional micro-nano structure processing technology, uses common conventional materials, and adapts the maskless laser direct writing process in the photolithography technology to realize large-scale and mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 It is a structural diagram of the present invention.

[0023] Figure 2 This is the emissivity spectrum of the present invention at a positive angle.

[0024] Figure 3 This is the emissivity diagram at a spatial angle of 0-89 degrees under TE polarization of the present invention.

[0025] Figure 4 This is the electric field distribution diagram of the present invention in the resonance mode.

[0026] Figure 5 This is a graph of the multi-level expanded scattering cross section contribution in the resonance mode of the present invention.

[0027] Figure 6 This is a diagram for regulating the emission rate and Q value in the continuum bound state theory of the present invention.

[0028] Figure 7 This is a relationship diagram between the structural ratio parameter S and the emissivity wavelength of the present invention. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0032] Example 1

[0033] Reference Figure 1 to Figure 7, which is the first embodiment of the present invention, provides an angle-independent narrow-spectrum thermal emitter design based on a continuum bound state design, which includes a metal substrate; a plurality of dielectric cylinders, the plurality of dielectric cylinders are arranged on the metal substrate and in a regular hexagonal shape;

[0034] Each dielectric cylinder includes a low-refractive-index dielectric cylinder disposed on a metal substrate; and a high-refractive-index dielectric cylinder disposed on the low-refractive-index dielectric cylinder.

[0035] Furthermore, the diameter of the low refractive index medium cylinder is D, and the side length of the regular hexagonal arrangement of multiple medium cylinders is The height of the high refractive index medium cylinder is H1, and the height of the low refractive index medium cylinder is H2

[0036] Furthermore, the metal substrate is selected from one of gold, silver, aluminum, and tungsten; the low refractive index medium cylinder is selected from one of silicon dioxide, magnesium fluoride, and zinc sulfide; and the high refractive index medium cylinder is selected from one of amorphous silicon, germanium, and indium arsenide.

[0037] Furthermore, the metal substrate is gold, the low refractive index medium cylinder is silicon dioxide, and the high refractive index medium cylinder is germanium with a refractive index of 4.0.

[0038] Furthermore, the thickness of the metal substrate is greater than 0.1 micron; the height H2 of the low refractive index medium cylinder is 0.31-0.44 micron, and the diameter D of the low refractive index medium cylinder is 0.85-1.2 micron; the height H1 of the high refractive index medium cylinder is 0.56-0.79 micron, and the diameter of the high refractive index medium cylinder is 0.85-1.2 micron.

[0039] Furthermore, Mie resonance modes coupled by magnetic dipoles and electric quadrupoles are generated in multiple dielectric cylinders.

[0040] Furthermore, under transverse electric TE polarization, the displacement of the emission peak wavelength of the angle-independent narrow-spectrum thermal emitter in the angle range of 0-89 degrees relative to the 0-degree emission peak wavelength is less than 1%.

[0041] Furthermore, the emissivity and emission Q value of the angle-independent narrow-spectrum thermal emitter can be controlled by adjusting the height H2 of the low-refractive-index medium cylinder.

[0042] Furthermore, at 0 degrees positive emission, the narrow spectrum emission of the angle-independent narrow spectrum thermal emitter has the same Q value under transverse electric TE polarization and transverse magnetic TM polarization, the Q value is greater than 600, and the narrow spectrum emissivity is greater than 0.9

[0043] Furthermore, the emission peak wavelength of the angle-independent narrow-spectrum thermal emitter is proportional to the structural proportionality coefficient S, and the emission peak wavelength is within the 3-6 micron band.

[0044] It should be noted that narrow-spectrum thermal emitters, as key devices for infrared spectrum detection, are widely used in gas detection, spectral analysis, thermal radiation control and other fields. Traditional narrow-spectrum thermal emitters are mainly based on mechanisms such as photonic crystals, surface plasmon resonance, Tamm mode and Fabry-Perot resonant cavity to achieve narrow-band emission of specific wavelengths. These structures usually adopt metal-dielectric composite structures, and localized resonance modes are formed at specific wavelengths by regulating structural parameters, thereby obtaining narrow-band emission characteristics. However, since these resonance modes usually depend on the wave vector of the incident light, the emission characteristics show a strong dependence on the incident angle and polarization state, which limits its performance in practical applications.

[0045] The narrow-spectrum thermal emitters in the prior art generally have the following problems: First, although the structure based on surface plasmon resonance can achieve a strong localized light field, its resonance quality factor Q value is low, with a typical value of only 50-200, which is difficult to meet the needs of high-precision gas detection; second, although the structure based on photonic crystals and Fabry-Perot resonant cavities can obtain a higher Q value, its emission characteristics are highly sensitive to the incident angle, and there will be obvious peak drift at large angles of incidence, and it will show significant differences under different polarization states; third, the emission peak and Q value control means of the existing structure are limited, and it is difficult to flexibly adjust the emission characteristics according to actual application requirements. These problems seriously restrict the application of narrow-spectrum thermal emitters in fields such as high-precision multi-channel gas detection. Therefore, it is of great theoretical significance and practical value to develop a narrow-spectrum thermal emitter with high Q value, angle-independent characteristics and controllable.

[0046] It is further necessary to explain that if Figures 1 to 7 As shown, according to the present invention, an angle-independent narrow-spectrum emitter design structure based on a continuum bound state design for NDIR gas detection technology is provided, and the structure is composed of a low-emissivity metal layer and high- and low-refractive index medium cylinders, and the cylinders are arranged in a regular hexagonal pattern in the structure. The low-emissivity metal layer can be one of gold, silver, aluminum and tungsten, the low-refractive index medium layer material can be one of silicon dioxide, magnesium fluoride and zinc sulfide, and the high-refractive index medium layer material can be one of amorphous silicon, germanium and indium arsenide.

[0047] The diameter of the dielectric column of the structure is D, and the length of the regular hexagonal array is The height H1 of the high refractive index medium cylinder and the height H2 of the low refractive index cylinder are both within the subwavelength range. The resonant absorption behavior of the structure in a specific band within the cylinder is the main reason for its narrow-spectrum emission under TE polarization. At this time, the electromagnetic field is localized within the high refractive index cylinder, where the electric field mainly presents electric quadrupoles and the magnetic field presents the characteristics of magnetic dipoles. And the band of this resonant mode is less affected by changes in spatial angles. And the emissivity and Q value can be flexibly adjusted based on the continuum bound state theory, with good designability.

[0048] Preferably, Au with low emissivity and low material loss in the infrared band of 3-6 microns is selected as the material of the metal layer, and its thickness is greater than 100nm, and germanium with a refractive index of 4.0 in 3-6 microns is selected as a lossless high refractive index material. The intermediate low refractive index material is silicon dioxide. The height H2 of the silicon dioxide cylinder ranges from 0.31 to 0.44 microns, and the diameter D ranges from 0.85 to 1.2 microns; the height H1 of the germanium cylinder ranges from 0.56 to 0.79 microns, and the diameter ranges from 0.85 to 1.2. The thickness of each layer is regulated by the continuum bound state theory to adjust the appropriate Q value and emissivity, and the peak wavelength of the resonant emissivity is adjusted by the proportional coefficient of the overall structure. Combined with electromagnetic theory, the emissivity of the designed structure is calculated using the public rigorous coupled wave analysis method. The preferred structure can achieve narrow-spectrum emission with high Q value in the infrared range of 3-6 microns. The Q value under TE polarization is greater than 700, and the emissivity is greater than 0.9. The spectrum line is independent of the spatial angle. In the 0-89 angle range, the ratio of the emission peak offset to the emission peak is less than 1%. Compared with other common narrow-spectrum thermal emitter designs, the present invention can solve the problem of difficult performance balance between spatial angle dispersion and high Q value. The following is a further explanation of this description in conjunction with the accompanying drawings.

[0049] Better, Figure 1 It is a schematic diagram of the design structure of the angle-independent narrow-spectrum emitter based on continuum bound state design for NDIR gas detection of the present invention, wherein the yellow structure represents metallic gold, the light green layer represents a low-refractive-index silica cylinder, and the gray layer represents a high-refractive-index germanium cylinder.

[0050] Figure 2 This is the preferred angle-independent narrow-spectrum emitter based on continuum bound state design under TE polarization. The emissivity in the figure is calculated using the rigorous coupled wave analysis method to obtain the reflectivity R and transmittance T of the structure. According to the law of energy conservation, the absorptivity of the structure can be obtained: A = 1-TR. Finally, according to Kirchhoff's law, the absorptivity is equal to the emissivity ε = A. The emissivity Q value can be calculated to be 702. And the resonance wavelength value of the emission peak is within the absorption peak of carbon dioxide gas.

[0051] Figure 3 This is a graph showing the emissivity of the angle-independent narrow-spectrum emitter based on the preferred continuum bound state design. The emissivity changes with the spatial angle from 0 degrees to 89 degrees under TE polarization. The calculation method of the emission spectrum is the same as Figure 2 Similarly, it can be seen from the figure that during the angle change of the framed research mode, the ratio of the offset of the emission peak wavelength to the 0-degree emission peak wavelength is less than 1%.

[0052] Figure 2-Figure 3 The calculation results show that the emitter based on the continuum bound state design in the present invention can achieve high Q value spatial angle-independent emission characteristics in the infrared 3-6 micron band, and the resonance wavelength of the emission peak is within the gas absorption peak range of carbon dioxide. This narrow-band spatial angle-independent emission characteristic can further improve the signal-to-noise ratio of infrared signals and the utilization rate of effective energy.

[0053] Figure 4 It is the electromagnetic field distribution diagram of the structure in the resonance mode. It can be seen from the electromagnetic field distribution diagram in the resonance mode that the electromagnetic field is localized in the dielectric cylinder in the TE resonance mode. And the electric field distribution in the xz section shows the distribution characteristics of the electric quadrupole. The magnetic field distribution in the xz section shows the distribution characteristics of the magnetic dipole. Further using the public electromagnetic field multi-level expansion solution method, the electromagnetic field in the dielectric cylinder under study is numerically expanded and calculated to calculate the contribution of its electric dipole, magnetic dipole, electric quadrupole and magnetic quadrupole to the unit body in the far-field scattering cross section. Figure 5 The calculation results show that the magnetic dipole and electric quadrupole play an absolutely dominant role in the resonance mode. Figure 4 The calculated results are consistent with those of the previous study. The peak value of the scattering cross section of the magnetic dipole is much higher than that of the electric quadrupole. Therefore, the contribution of the magnetic dipole to the far-field emissivity is more significant. This result further confirms the excitation of the magnetic dipole in the germanium cylinder.

[0054] Figure 6It is the ability of the structure to flexibly adjust the emissivity and Q value based on the continuum bound state design theory. It can be seen that in the parameter space, when far away from the BIC point, H2 = 470nm, the emission first increases to 1, that is, perfect emission, and then decreases while the Q value of the structure decreases rapidly. Two perfect emission points can be observed on both sides of the BIC point, at H2 = 420nm and H2 = 520nm. At this time, the radiation loss of the structure in the open system is the same as the non-radiative loss. These two points are called quasi-continuum bound state modes (QBIC) that appear simultaneously with the BIC mode. In this continuous change process, the emissivity increases from 0.81 to 1 and then rapidly decays to 0, then increases to 1 and then decays to 0.77. At the same time, the Q value increases from 420 to more than 1500 and then decreases to 500. The calculation results show that the structure has the ability to flexibly adjust the emissivity and Q value.

[0055] Figure 7 The structural ratio parameter S of the structure and the peak wavelength of the emissivity are shown in Figure 2. The structural ratio parameter S refers to the size ratio before and after the structure is changed. In this structure, the diameter of the dielectric column (D) and the length of the regular hexagonal array The height H1 of the high refractive index medium cylinder and the height H2 of the low refractive index cylinder change simultaneously according to the proportional parameters. It can be seen from the figure that the peak wavelength of the emissivity is positively linearly correlated with the structural proportional parameter S. Therefore, the peak wavelength of the emissivity can be flexibly adjusted by changing the proportional parameters of the structure, thereby matching the absorption peaks of various gases within the infrared range of 3-6 microns.

[0056] The present invention provides an angle-independent narrow-spectrum thermal emitter design based on a continuum bound state design. The structure can achieve narrow-spectrum emission with a high Q value (narrower narrow spectrum half-peak) in the infrared band of 3-6 microns, and is independent of the spatial angle under TE polarization, and can achieve narrow-spectrum emission with tunable emission peak and Q value by adjusting the geometric parameters. Further, the narrow-spectrum emission peak can be controlled within any band of interest by using the proportionality coefficient. On the one hand, the structure utilizes the theoretical design of the continuum bound state, while reducing the structural metal layer, to achieve emission with a higher Q value (Q value can reach). On the other hand, the structure utilizes the magnetic dipole-dominated mode and the regular hexagonal arrangement. Under TE polarization, the emission peak wavelength hardly changes with the spatial angle, thereby overcoming the problem that the current common narrow-spectrum emitters have low Q values, are difficult to effectively control the Q value, and are sensitive to angle space. A new angle-independent narrow-spectrum emitter design strategy is provided for the miniaturized integration of multi-gas channel infrared detection devices with higher precision and sensitivity. At the same time, the structure of the present invention is compatible with traditional micro-nano structure processing technology, uses common conventional materials, and can use maskless laser direct writing technology to achieve large-scale mass production.

[0057] In summary, the present invention successfully realizes a narrow-spectrum thermal emitter with significant technical advantages by constructing a double-layer dielectric cylindrical array structure of a specific size on a metal substrate and using the coupling of magnetic dipoles and electric quadrupoles to generate Mie resonance modes. First, the structure exhibits excellent angle-independent characteristics under transverse electric TE polarization, and the offset of the emission peak wavelength in a large angle range of 0-89 degrees is less than 1%, which overcomes the problem that the emission characteristics in the prior art are highly sensitive to the incident angle; secondly, the Q value obtained by the present invention can exceed 600, which is significantly higher than the traditional structure based on surface plasmon resonance (the Q value is usually 50-200), which provides the possibility for high-precision gas detection; thirdly, by adjusting the height H2 of the low-refractive index dielectric cylinder, the emissivity and Q value can be effectively regulated, and the emission peak wavelength is linearly related to the structural proportional coefficient, realizing flexible tuning within the 3-6 micron band; finally, at the time of positive emission, the structure has the same Q value under transverse electric TE polarization and transverse magnetic TM polarization, reflecting good polarization characteristics. These characteristics give the present invention unique application advantages in the fields of multi-channel gas detection, and provide a new technical solution for the miniaturized integration of high-precision infrared detection devices.

[0058] Example 2

[0059] Reference Figure 1 to Figure 7 , which is the second embodiment of the present invention, aims to design a spatial angle-independent narrow-spectrum thermal emitter design that can be applied to non-spectral infrared detection technology to solve the problem of difficult design balance between spatial angle dispersion and high Q value of existing narrow-spectrum emitters.

[0060] An angle-independent narrow-spectrum emitter structure based on continuum bound state design of the present invention

[0061] It is composed of metal layers, low-refractive index and high-refractive index medium material cylinders. The cylinders are arranged in a regular hexagonal pattern in space.

[0062] Preferably, the regular hexagonal arrangement of the structure is characterized by a diameter of the dielectric column (D) and a length of the regular hexagonal array of The height H1 of the high refractive index medium cylinder and the height H2 of the low refractive index medium cylinder are both within the sub-wavelength range.

[0063] Preferably, the material of the metal substrate of the structure can be selected from one of gold, silver, aluminum and tungsten, the material of the low refractive index dielectric layer can be selected from one of silicon dioxide, magnesium fluoride and zinc sulfide, and the material of the high refractive index dielectric layer can be selected from one of amorphous silicon, germanium and indium arsenide.

[0064] Preferably, the structure uses Au as the metal material, silicon dioxide in the infrared band of 3-6 microns as the low refractive index material, and germanium with a refractive index of 4.0 as the high refractive index medium material.

[0065] Preferably, the thickness of the metal Au substrate used is greater than 0.1 micron to provide a high-quality lower emissivity layer; the height H2 of the silicon dioxide column ranges from 0.31-0.44 microns, and the diameter (D) ranges from 0.85-1.2 microns; the height H1 of the germanium column ranges from 0.56-0.79 microns, and the diameter ranges from 0.85-1.2.

[0066] Among them, the high-Q narrow-spectrum mode of the structure is excited by the Mie resonance in the cylinder. By expanding the electromagnetic field in the cylinder, it can be seen that its mode is the coupling of magnetic dipole and electric quadrupole.

[0067] The emission spectrum of the resonance mode exhibits an angle-independent characteristic under TE polarization, and within the angle range of 0-89, the ratio of the offset of the emission peak wavelength to the 0-degree emission peak wavelength is less than 1%.

[0068] Among them, this resonance mode is independent of TE and TM polarization at the time of positive emission, and the Q value is higher than 600. And the narrow spectrum emissivity is greater than 0.9.

[0069] Among them, the resonance mode can control the emissivity and Q value through the continuum bound state theory, and the specific control parameter is the height H2 of the low refractive index cylinder.

[0070] The wavelength of the emission peak of the structure is proportional to the proportional coefficient S of the structure. Therefore, it can be controlled according to the proportional coefficient in the infrared band of 3-6 microns.

[0071] In summary, the angle-independent narrow-spectrum emitter used in the NDIR gas detection technology of the present invention can achieve a high-Q value emission of 3-6 microns by scaling the size of the high and low refractive index medium cylinders on the metal reflective layer. Its emission peak is proportional to the proportional coefficient S of the structure, and can be flexibly adjusted to match the infrared absorption peaks of various gases.

[0072] Compared with the current MIM infrared emitter, whose positive emission Q value is limited to 10-20, this structure utilizes the theoretical design of continuum bound states and reduces the structural metal layer to achieve emission with a higher Q value (Q value can reach ), which can further improve the accuracy and sensitivity of NDIR gas detection.

[0073] Compared with the defects of most current metasurface narrow spectrum emitters that are difficult to simultaneously meet the performance requirements of spatial angle dispersion and high Q value, this structure uses the mode dominated by magnetic dipoles and the regular hexagonal arrangement. Under TE polarization, the emission peak wavelength hardly changes with the spatial angle. In the 0-89 angle range, the ratio of the emission peak wavelength offset to the 0-degree emission peak wavelength is less than 1%, thereby improving the utilization rate of effective radiation energy in space.

[0074] The structure of the present invention is compatible with traditional micro-nano structure processing technology, uses common conventional materials, and adapts the maskless laser direct writing process in photolithography technology to achieve large-scale and mass production.

[0075] It is important to note that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An angle-independent narrow-spectrum thermal emitter design based on continuum bound state design, characterized by: include, Metal substrate; A plurality of dielectric cylinders, wherein the plurality of dielectric cylinders are disposed on the metal substrate and arranged in a regular hexagon; Each of the dielectric cylinders includes a low-refractive-index dielectric cylinder disposed on the metal substrate; and a high-refractive-index dielectric cylinder disposed on the low-refractive-index dielectric cylinder.

2. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 1, characterized in that: The diameter of the low refractive index medium cylinder is D, and the side length of the regular hexagonal arrangement of the plurality of medium cylinders is The height of the high refractive index medium cylinder is H1, and the height of the low refractive index medium cylinder is H2.

3. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 1, characterized in that: The metal substrate is selected from one of gold, silver, aluminum and tungsten; the low refractive index medium cylinder is selected from one of silicon dioxide, magnesium fluoride and zinc sulfide; and the high refractive index medium cylinder is selected from one of amorphous silicon, germanium and indium arsenide.

4. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 3, characterized in that: The metal substrate is gold, the low refractive index medium cylinder is silicon dioxide, and the high refractive index medium cylinder is germanium with a refractive index of 4.

0.

5. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 4, characterized in that: The thickness of the metal substrate is greater than 0.1 micron; the height H2 of the low refractive index medium cylinder is 0.31-0.44 micron, and the diameter D of the low refractive index medium cylinder is 0.85-1.2 micron; the height H1 of the high refractive index medium cylinder is 0.56-0.79 micron, and the diameter of the high refractive index medium cylinder is 0.85-1.2 micron.

6. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 1, characterized in that: Mie resonance modes coupled by magnetic dipoles and electric quadrupoles are generated in the plurality of dielectric cylinders.

7. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 1, characterized in that: Under transverse electric TE polarization, the displacement of the emission peak wavelength of the angle-independent narrow-spectrum thermal emitter within the angle range of 0-89 degrees relative to the 0-degree emission peak wavelength is less than 1%.

8. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 1, characterized in that: The emissivity and emission Q value of the angle-independent narrow-spectrum thermal emitter are regulated by adjusting the height H2 of the low-refractive-index medium cylinder.

9. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 1, characterized in that: At 0 degree positive emission, the narrow spectrum emission of the angle-independent narrow spectrum thermal emitter has the same Q value under transverse electric TE polarization and transverse magnetic TM polarization, the Q value is greater than 600, and the narrow spectrum emissivity is greater than 0.

9.

10. The angle-independent narrow-spectrum thermal emitter design based on continuum bound state design as claimed in claim 1, characterized in that: The emission peak wavelength of the angle-independent narrow-spectrum thermal emitter is proportional to the structural proportionality coefficient S, and the emission peak wavelength is within the range of 3-6 micrometers.

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