Epitaxial structure for light absorber and light absorber

Abstract

The invention discloses an epitaxial structure for a light absorber and the light absorber. The epitaxial structure for the light absorber comprises a first metal layer, a dielectric substance layer and a second metal layer which are arranged in sequence, wherein the second metal layer is provided such that, when light of a set wavelength [lambda] 0 is irradiated thereon, non-Hermite conjugate coupling can occur, and the set wavelength [lambda] 0 is a resonance wavelength of the second metal layer; the first metal layer, the dielectric substance layer and the second metal layer are arranged in a way that at least part of a coupling field generated by non-Hermite conjugate coupling of the second metal layer can be subjected to destructive interference with the first metal layer. At least part of a coupling field generated by non-Hermite conjugate coupling of the second metal layer can be subjected to destructive interference with the first metal layer, so that the intensity of a coherently superposed reflection field is almost zero, and nearly perfect absorption with a high Q value is realized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an epitaxial structure for a light absorber and the light absorber. Background Art

[0002] The Q value (Quality Factor) of an optical absorber is a key parameter for measuring its optical resonant performance. It reflects the balance between the ability of light to store energy within the absorber and the rate of energy loss. The higher the Q value, the longer the light "resides" within the absorber, and the slower the energy loss. The lower the Q value, the faster the energy is absorbed or dissipated. Since high-Q perfect absorption can provide near-100% light absorption within a specific narrow spectral range, it has great potential in light detection, thermal emission, and sensors.

[0003] However, although metal materials (such as gold and silver) have a high absorption coefficient, their intrinsic loss is relatively large, resulting in their resonant absorption spectra generally having a low Q value, typically Q<10. Summary of the Invention

[0004] In order to solve at least one of the above problems, according to one aspect of the present invention, an epitaxial structure for a light absorber is provided.

[0005] This epitaxial structure for a light absorber includes a first metal layer, a dielectric layer, and a second metal layer arranged in sequence. The second metal layer is configured so that when light of a set wavelength λ0 is irradiated on it, it undergoes non-Hermitian coupling, with the set wavelength λ0 being the resonant wavelength of the second metal layer. The first metal layer, the dielectric layer, and the second metal layer are configured so that at least part of the coupling field generated by the non-Hermitian coupling in the second metal layer can destructively interfere with the first metal layer. Because near-perfect absorption occurs at the resonant wavelength, this wavelength excites strong non-conjugated coupling, forming a unique bound state. Therefore, the resonant wavelength of the second metal layer is selected to be the set wavelength λ0.

[0006] Because the coupling field generated by the non-Hermitian conjugate coupling of the second metal layer can at least partially interfere with and cancel the first metal layer, the intensity of the coherently superimposed reflection field is almost zero, achieving near-perfect absorption (absorption rate can exceed 98%) with a high Q value (Q value can be as high as 176).

[0007] In some embodiments, the second metal layer comprises a nanoantenna array, comprising at least one array unit, each comprising at least two metal nanoantennas. The gap between adjacent metal nanoantennas is g = s*a, where a is the side length of the metal nanoantenna, 0.1a ≤ s ≤ 5a, and a < λ0 / 2. When light of a predetermined wavelength λ0 is irradiated into the nanoantenna array, the gap g between adjacent metal nanoantennas is much smaller than the predetermined wavelength λ0, thereby exciting localized plasmon resonance in the nanoantenna array, causing non-Hermitian conjugate coupling between adjacent metal nanoantennas. Near the resonant wavelength, the localized field is confined to the gaps between the metal nanoantennas, thereby forming a dark state around the metal nanoantennas. This effectively reduces the interaction between the light field and the metal material, thereby reducing the metal material's absorption of the light field and achieving a high-Q resonant mode. Simultaneously, the light field in this resonant mode couples with the first metal layer. When the coupled field between the metal nanoantennas destructively interferes with the reflected field from the first metal layer, the intensity of the coherently superimposed reflected field is reduced to almost zero, achieving near-perfect absorption with a high-Q value.

[0008] In some embodiments, the opposite sides of adjacent metal nanoantennas are arranged parallel to each other, thereby increasing the coupling area between adjacent antennas and enhancing the non-conjugate coupling effect.

[0009] In some embodiments, the first metal layer is disposed on a substrate, so that the substrate provides support for the first metal layer, and the first metal layer is configured as a thin film structure.

[0010] In some embodiments, the smallest unit of the array elements is arranged in the shape of a regular polygon. This arrangement allows the array elements to be regular polygons, ensuring equal coupling strength and wavelength in the x and y directions, enhancing the excitation efficiency of the quasi-bound state at the set wavelength λ0 and achieving near-perfect absorption. If the arrangement is not a regular polygon, the non-conjugated coupling strengths of the xy polarized light excitation will be unequal, affecting the excitation of the quasi-bound state and thus preventing near-perfect light absorption.

[0011] In some embodiments, the cross-section of the metal nanoantenna is an equilateral triangle, square, or regular hexagon. When the cross-section of the metal nanoantenna is an equilateral triangle, the smallest unit of the array unit contains at least six metal nanoantennas, and the smallest units are arranged in the shape of a regular hexagon. When the cross-section of the metal nanoantenna is a square, the smallest unit of the array unit contains at least four metal nanoantennas, and the smallest units are arranged in the shape of a square. When the cross-section of the metal nanoantenna is a regular hexagon, the smallest unit of the array unit contains at least three metal nanoantennas, and the smallest units are arranged in the shape of an equilateral triangle. This ensures that the opposing sides of adjacent metal nanoantennas are arranged parallel to each other.

[0012] In some embodiments, the cross-section of the metal nanoantenna is an equilateral triangle, a square, or a regular hexagon; when the cross-section of the metal nanoantenna is an equilateral triangle or a regular hexagon, the array units are arranged in the shape of a regular hexagon, and when the cross-section of the metal nanoantenna is a regular hexagon, the number of metal nanoantennas included in the hexagonal structure is 1+6n, n≥1, and n is an integer; when the cross-section of the metal nanoantenna is a square, the array units are arranged in the shape of a square, and the number of metal nanoantennas included in the square structure is n*n, n≥2, and n is an integer. Therefore, the array unit can be provided with a corresponding number of metal nanoantennas as needed: for example, when the cross-section of the metal nanoantenna is an equilateral triangle, the array unit includes 6 equilateral triangles; for another example, when the cross-section of the metal nanoantenna is a regular hexagon, the array unit includes 7, 13, 19, 25, etc. metal nanoantennas, as long as the number of metal nanoantennas meets 1+6n, n≥1, and n is an integer; for another example, when the cross-section of the metal nanoantenna is a square, the array unit includes 4, 9, 16, 25, etc. metal nanoantennas, as long as the number of metal nanoantennas meets n*n, n≥2, and n is an integer.

[0013] In some embodiments, the nanoantenna array includes at least two array units, and the period between two adjacent array units is p, p < λ0, p > 2(a + s). This not only prevents overlapping of adjacent array units, but also prevents diffraction, ensuring effective light absorption.

[0014] In some embodiments, multiple array elements are arranged in a regular triangular lattice or a square lattice to form a nanoantenna array. This regular triangular lattice or square lattice arrangement ensures equal coupling strength and coupling wavelength in the x and y directions, enhancing the excitation efficiency of the quasi-bound state at the set wavelength λ0 and achieving near-perfect absorption.

[0015] In some embodiments, the thickness H of the first metal layer is m The value range is H m ≥50nm, the thickness of the dielectric layer H s The value range is 50nm≤H s ≤λ0 / 2, and / or the thickness h of the second metal layer is in the range of 30nm≤h≤500nm. Due to the localized plasmon resonance coupling between the first metal layer and the second metal layer, the first metal layer mainly plays the role of reflecting the light field and coupling, which is usually greater than H mStrong reflection can be achieved when the thickness is ≥50nm; the second metal layer plays the role of exciting localized plasma resonance and coupling. Different thicknesses are required to achieve high-efficiency excitation according to different target wavelengths (i.e., resonance wavelengths). From ultraviolet to terahertz bands, the required thickness is usually in the range of 30nm≤h≤500nm. The thickness of the dielectric layer H s This affects the localized plasmon resonance coupling between the first and second metal layers, which requires a certain range to achieve near-perfect absorption. This can be optimized through FDTD simulation. As a result, the coupling field generated by the non-Hermitian conjugate coupling in the second metal layer can at least partially interfere with and cancel the first metal layer, reducing the intensity of the coherently superimposed reflected field to almost zero, achieving near-perfect absorption with a high Q value.

[0016] In some embodiments, the thickness H of the dielectric layer s ≈λ0 / n eff , where n eff is the effective refractive index of the dielectric layer. Since the thickness of the metal layer also affects the local field distribution, the thickness of the dielectric layer H s This can also be obtained through FDTD simulation. Thus, the coupling field generated by the non-Hermitian conjugate coupling of the second metal layer can at least partially interfere with and cancel the first metal layer, making the intensity of the coherently superimposed reflected field almost zero, achieving near-perfect absorption with a high Q value.

[0017] In some embodiments, the dielectric material is transparent when the operating wavelength is set to λ 0. Thus, the coupling field generated by the non-Hermitian conjugate coupling of the second metal layer can at least partially destructively interfere with the first metal layer.

[0018] In some embodiments, at least one of the first metal layer and the second metal layer is a metal material.

[0019] In some embodiments, the dielectric layer is made of at least one of SiO2, TiO2, Al2O3, and MgF2. Because SiO2, TiO2, Al2O3, and MgF2 have low light absorption and excellent processing properties, they improve the performance of the epitaxial structure of the light absorber while ensuring production efficiency and product quality.

[0020] In some embodiments, at least one of the first metal layer and the second metal layer is made of at least one of Al, Ag, Au, and Cu. Since these materials are chemically stable, they can excite LSPs more efficiently.

[0021] According to another aspect of the present invention, a light absorber is provided, which includes the aforementioned epitaxial structure for a light absorber. FDTD simulation proves that the maximum absorption of this method in the near-infrared band exceeds 98%, and the Q value is as high as 176. By designing different structural parameters and different metal / dielectric materials, this method can be applied to almost all wavelengths from the ultraviolet to the terahertz band by changing the structural parameters and materials. For example, the wavelength of the ultraviolet band is small, and the corresponding structural size is smaller. It is more appropriate to use Al as the first metal layer / second metal layer because Al has less light absorption in the ultraviolet band and is more efficient in exciting LSPs; it is more appropriate to use Au / Ag in long-wave bands such as the near-infrared band because they are more chemically stable and have less light absorption in the long-wave band. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of an epitaxial structure for a light absorber according to one embodiment of the present invention;

[0023] Figure 2 for Figure 1 A schematic structural diagram of an embodiment of an epitaxial structure for a light absorber is shown;

[0024] Figure 3 for Figure 1 A schematic structural diagram of another embodiment of an epitaxial structure for a light absorber is shown;

[0025] Figure 4 for Figure 2 A schematic cross-sectional structure diagram of an epitaxial structure for a light absorber along the AA direction is shown;

[0026] Figure 5 for Figure 1 A schematic structural diagram of an array unit of an embodiment of an epitaxial structure for a light absorber is shown;

[0027] Figure 6 for Figure 1 A schematic structural diagram of an array unit of another embodiment of an epitaxial structure for a light absorber is shown;

[0028] Figure 7 Schematic diagram of an epitaxial structure for a light absorber according to an embodiment of the present invention;

[0029] Figure 8 Schematic diagram of another embodiment of an epitaxial structure for a light absorber according to one embodiment of the present invention;

[0030] Figure 9 for Figure 7 A schematic structural diagram of an array unit of an epitaxial structure for a light absorber is shown;

[0031] Figure 10 Schematic diagram of an epitaxial structure for a light absorber according to an embodiment of the present invention;

[0032] Figure 11 for Figure 10 A schematic structural diagram of an array unit of an embodiment of an epitaxial structure for a light absorber is shown;

[0033] Figure 12 is a schematic structural diagram of an array unit according to another embodiment;

[0034] Figure 13 A schematic diagram of the transmission spectrum of the light absorber of the present application irradiated with a specific wavelength;

[0035] Reference numerals: 20 , substrate; 30 , first metal layer; 40 , dielectric layer; 50 , second metal layer; 51 , array unit; 510 , structural unit; 511 , metal nanoantenna. DETAILED DESCRIPTION

[0036] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0037] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include" and "comprise" include not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such processes, methods, articles or equipment. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or equipment that includes the elements. The terms used in this article are generally terms commonly used by those skilled in the art. If they are inconsistent with commonly used terms, the terms in this article shall prevail.

[0038] Furthermore, for ease of description, spatially relative terms such as "below," "beneath," "lower," "above," and "upper" may be used herein to describe the relationship of one element or component to another (or additional) elements or components as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0039] In this article, the term "non-Hermitian conjugate coupling" refers to a special coupling mechanism in non-Hermitian physical systems. Its core lies in the presence of asymmetric gain-loss distribution and complex coupling coefficients in the system, which leads to energy exchange and mode interaction in a way that is completely different from that of traditional Hermitian systems. Its essence is to achieve fine control of the energy flow and resonance characteristics of the system through asymmetric complex coupling coefficients and gain-loss balance. Among them, a non-Hermitian physical system refers to a system whose Hamiltonian H does not satisfy the Hermitian property (i.e. ), allowing for gain (such as population inversion in the laser medium) or loss (such as material absorption, radiation leakage). Conjugate coupling means that its coupling coefficient has a complex conjugate relationship, for example, the coupling between two modes satisfies ( represents the complex conjugate), in this case, the energy transfer between modes is asymmetric. For example, when one mode injects energy into another mode, the phase or amplitude of the reverse transfer is different.

[0040] In this article, the term "coupled field" refers to a field system in which two or more physical fields are interconnected through interaction (coupling). This interaction causes the properties of the fields (such as energy, momentum, and phase) to influence each other, forming a dynamic equilibrium or coevolution.

[0041] In this article, the term "localized plasmon resonance" refers to a physical phenomenon in which free electrons in nanoscale metal structures oscillate collectively under the influence of a light field. This resonance can lead to strong absorption or scattering of light of specific wavelengths.

[0042] In this article, the term "resonant wavelength" refers to the specific wavelength corresponding to the eigenmode of the system under non-Hermitian coupling conditions. It corresponds to the matching of the collective oscillation of free electrons in the system (surface plasmon resonance, SPR) with the frequency of the incident light.

[0043] In this article, the term "local field" refers to a physical field (such as electromagnetic field, acoustic field, etc.) that is highly confined or significantly enhanced within a specific spatial range, and its energy cannot propagate freely or can only be maintained in a limited area.

[0044] In this article, the term "dark state" refers to an eigenstate in a quantum system, optical system, or electromagnetic coupling structure that cannot exchange energy with the outside world through radiation.

[0045] In this article, the term "light field" is a complete representation of a collection of light rays in space, which records information such as the position, direction, intensity, wavelength, etc. of the light rays in space.

[0046] In this article, the term "reflection field" describes the collection of all light rays emitted from the surface of an object, centered at the light-emitting point on the surface of the object.

[0047] In this article, the term "diffraction" is a property of wave phenomena, which refers to the phenomenon that when a wave encounters an obstacle, a slit, or passes through a small hole, the propagation direction of the wave will change and bypass the edge of the obstacle or form complex interference and intensity distribution behind the slit.

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0049] Figures 1 to 6 An epitaxial structure for a light absorber according to an embodiment of the present application is exemplarily shown.

[0050] like Figure 1 and Figure 4 As shown, the epitaxial structure for the light absorber includes a first metal layer, a dielectric layer and a second metal layer arranged in sequence (eg, along the Z direction).

[0051] As an example of the second metal layer, Figure 2 and Figure 3 As shown, the second metal layer includes a plurality of metal nano-antennas. The cross section of the metal nano-antenna is a regular hexagon. Figure 2 、 Figure 3 and Figure 5 As shown, 1+6n metal nanoantennas are arrayed in a regular hexagonal shape (along the X and Y directions) to form an array unit, and a metal nanoantenna is arranged in the center of the array unit; the outer circle of the centrally arranged metal nanoantennas increases by 6m per circle; for example, the m value of the first circle outside the centrally arranged metal nanoantenna is 1, and the number of metal nanoantennas in this circle is 6 (as shown in FIG. Figure 2 、 Figure 3 and Figure 5 As shown), the value of m in the second circle is 2, and the number of metal nanoantennas in this circle is 12 (as shown Figure 2 and Figure 3 As shown). Figure 5 As shown in , the gap between adjacent metal nanoantennas is g = s*a, where a is the side length of the metal nanoantenna, 0.1a≤s≤5a, and a<λ0 / 2. Figure 2 、 Figure 3 and Figure 5As shown, the opposing sides of adjacent metal nanoantennas are arranged parallel to each other, which helps increase the coupling area between adjacent antennas and thus enhance the non-conjugate coupling effect. The thickness h of the second metal layer ranges from 30nm≤h≤500nm. The period of two adjacent array units is p, p<λ0, p>2(a+s), where λ0 is the set wavelength of light irradiated on the epitaxial structure used for the light absorber to prevent diffraction, ensure the light absorption effect, and prevent overlapping of adjacent array units.

[0052] In some embodiments, as Figure 2 As shown, multiple array units are arranged in a regular triangle lattice (along the X and Y directions) to form a structural unit, and multiple structural units are arrayed (along the X and Y directions) to form a nanoantenna array to ensure that the coupling strength and coupling wavelength in the x and y directions are equal, enhance the excitation efficiency of the quasi-bound state at the set wavelength λ0, and achieve near-perfect absorption. In other embodiments, such as Figure 3 As shown, multiple array units are arranged in a regular hexagonal lattice (along the X and Y directions) to form a structural unit, and multiple structural units are arrayed (along the X and Y directions) to form a nanoantenna array.

[0053] In some embodiments, the second metal layer is made of metal, for example, at least one of Al, Ag, Au, and Cu, so as to improve the efficiency of exciting LSPs by using a second metal layer with relatively stable chemical properties.

[0054] As an example of the first metal layer, Figure 4 As shown, the thickness H of the first metal layer m The value range is H m The first metal layer is made of metal, for example, at least one of Al, Ag, Au and Cu, so as to improve the efficiency of exciting LSPs by using the first metal layer with relatively stable chemical properties.

[0055] As an example of a dielectric layer, Figure 4 As shown, the thickness of the dielectric layer H s The value range is 50nm≤H s ≤λ0 / 2. The dielectric layer is made of a material that is transparent when the operating wavelength is the set wavelength λ0, for example, at least one of SiO2, TiO2, Al2O3, and MgF2. By providing a dielectric layer with low light absorption and excellent processing performance, the performance of the epitaxial structure of the light absorber is improved while ensuring production efficiency and product quality.

[0056] In some embodiments, as Figure 4As shown, the first metal layer is disposed on a substrate. Specifically, the first metal layer, the dielectric layer, and the second metal layer are sequentially epitaxially formed on the substrate along the Z direction. The substrate can be made of a common substrate such as a sapphire substrate, a silicon substrate, or a silicon carbide substrate. The substrate provides support for the first metal layer, allowing the first metal layer to be configured as a thin film structure.

[0057] In other embodiments, Figure 6 As shown, 3R metal nanoantennas are arrayed in the shape of an equilateral triangle to form an array unit, R ≥ 1, R is an integer, so the number of metal nanoantennas in the array unit is 3 (as shown in FIG. Figure 6 As shown), 6, 9, 12 and so on.

[0058] Since the gap g between adjacent metal nanoantennas is much smaller than the period p of two adjacent array units, that is, g<<p; and since the period p of two adjacent array units is smaller than the set wavelength λ0 irradiated on the epitaxial structure for light absorber, the set wavelength λ0 is the resonant wavelength of the second metal layer, p<λ0, it can be seen that the gap g between adjacent metal nanoantennas is much smaller than the set wavelength λ0 irradiated on the epitaxial structure for light absorber, g<<λ0. When light of a set wavelength λ0 is irradiated on the epitaxial structure used for the light absorber, localized plasma resonance in the nanoantenna array on the second metal layer is stimulated, enabling non-Hermitian conjugated coupling to occur between adjacent metal nanoantennas. Near the resonant wavelength, strong non-conjugated coupling is stimulated to form a unique bound state. The local field is confined to the gaps between the metal nanoantennas, thereby forming a dark state around the metal nanoantennas, effectively reducing the interaction between the light field and the metal material, thereby reducing the metal material's absorption of the light field and achieving a high-Q resonant mode. At the same time, the resonant mode light field is coupled with the first metal layer, and the coupling field generated by the non-Hermitian conjugated coupling of the second metal layer can at least partially interfere with and cancel the first metal layer, making the coherently superimposed reflection field intensity almost zero, achieving near-perfect absorption with a high-Q value.

[0059] In some embodiments, the thickness H of the dielectric layer is s ≈λ0 / n eff , where n eff is the effective refractive index of the interlayer (i.e., dielectric layer) between the first metal layer and the second metal layer. Since the thickness of the metal layer also affects the local field distribution, the thickness of the dielectric layer H s This can also be obtained through FDTD simulation. Thus, the coupling field generated by the non-Hermitian conjugate coupling of the second metal layer can at least partially interfere with and cancel the first metal layer, making the intensity of the coherently superimposed reflected field almost zero, achieving near-perfect absorption with a high Q value.

[0060] Figures 7 to 9An epitaxial structure for a light absorber according to another embodiment of the present application is exemplarily shown.

[0061] The difference between the epitaxial structure for light absorber of this embodiment and the epitaxial structure for light absorber of the first embodiment is mainly as follows: Figures 7 to 9 As shown in , the cross section of the metal nanoantenna is an equilateral triangle. Figures 7 to 9 As shown, six metal nanoantennas are arranged in a regular hexagonal array (along the X and Y directions) to form an array unit, and no metal nanoantenna is arranged in the center of the array unit.

[0062] Figures 10 to 12 An epitaxial structure for a light absorber according to another embodiment of the present application is exemplarily shown.

[0063] The difference between the epitaxial structure for light absorber of this embodiment and the epitaxial structure for light absorber of the first embodiment is mainly as follows: Figures 10 to 12 As shown, the cross section of the metal nanoantenna is square. Figures 10 to 12 As shown, n*n metal nanoantennas are arranged in a square array (along the X and Y directions) to form an array unit, where n≥2 and n is an integer, i.e., the array unit contains 4 (e.g. Figure 12 As shown), 9 (as shown Figure 10 and Figure 11 As shown), 16, 25, etc. metal nanoantennas.

[0064] In some embodiments, as Figure 10 As shown, multiple array units are arranged in a square lattice (along the X and Y directions) to form a structural unit, and multiple structural units are arrayed (along the X and Y directions) to form a nanoantenna array to ensure that the coupling strength and coupling wavelength in the x and y directions are equal, enhance the excitation efficiency of the quasi-bound state at the set wavelength λ0, and achieve near-perfect absorption.

[0065] Based on the aforementioned embodiments of epitaxial structures for light absorbers, it can be concluded that the smallest unit cell of the array is arranged in the shape of a regular polygon. This allows the array cells to be arranged in a regular polygonal shape while ensuring equal coupling strength and wavelength in the x and y directions, enhancing the excitation efficiency of the quasi-bound state at the set wavelength λ0 and achieving near-perfect absorption. This avoids the problem of unequal non-conjugated coupling strengths for xy polarized light excitation, which can affect the excitation of the quasi-bound state and ultimately prevent near-perfect light absorption due to the irregular polygonal shape.

[0066] According to another aspect of the present invention, a light absorber is provided, comprising the aforementioned epitaxial structure for a light absorber.

[0067] When in use, when light is incident vertically from above or at a small angle (usually less than 10°), light within a specific narrow spectral range will be absorbed nearly 100%, while light in other wavelength ranges will be almost completely reflected, with the central wavelength of the absorption spectrum being λ0. Figure 13 As shown in the figure, FDTD simulation proves that the maximum absorption of this method in the near-infrared band exceeds 98%, and the Q value is as high as 176.

[0068] By designing different structural parameters and different metal / dielectric materials, this method can be applied to almost all wavelengths from ultraviolet to terahertz bands by changing the structural parameters and materials. For example, the wavelength in the ultraviolet band is small, and the corresponding structural size is smaller. It is more appropriate to use Al as the first metal layer / second metal layer because Al has less light absorption in the ultraviolet band and is more efficient in exciting LSPs; it is more appropriate to use Au / Ag in long-wave bands such as the near-infrared band because their chemical properties are more stable and their light absorption in the long-wave band is smaller.

[0069] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. An epitaxial structure for a light absorber, characterized in that It includes a first metal layer, a dielectric layer and a second metal layer arranged in sequence; wherein, The second metal layer is configured to undergo non-Hermitian conjugate coupling when light of a set wavelength λ0 is irradiated thereon, wherein the set wavelength λ0 is a resonance wavelength of the second metal layer; The first metal layer, the dielectric layer and the second metal layer are configured so that at least a portion of the coupling field generated by the non-Hermitian conjugate coupling of the second metal layer can cause interference destructive interaction with the first metal layer.

2. The epitaxial structure for a light absorber according to claim 1, wherein: The second metal layer is a nanoantenna array, which includes at least one array unit, and the array unit includes at least two metal nanoantennas. The gap between adjacent metal nanoantennas is g=s*a, where a is the side length of the metal nanoantenna, 0.1a≤s≤5a, and a<λ0 / 2.

3. The epitaxial structure for a light absorber according to claim 2, wherein: The opposite sides of adjacent metal nanoantennas are arranged parallel to each other; and / or The first metal layer is disposed on a substrate.

4. The epitaxial structure for a light absorber according to claim 3, wherein: The smallest unit of the array unit is arranged in the shape of a regular polygon.

5. The epitaxial structure for a light absorber according to claim 4, wherein: The cross section of the metal nanoantenna is a regular triangle, a square or a regular hexagon; When the cross section of the metal nanoantenna is an equilateral triangle, the smallest unit of the array unit includes at least six metal nanoantennas, and the smallest unit is arranged in the shape of a regular hexagon; When the cross-section of the metal nanoantenna is a square, the smallest unit of the array unit includes at least four metal nanoantennas, and the smallest unit is arranged in a square shape; When the cross section of the metal nanoantenna is a regular hexagon, the smallest unit of the array unit includes at least three metal nanoantennas, and the smallest unit is arranged in the shape of a regular triangle.

6. The epitaxial structure for a light absorber according to claim 4, wherein: The cross section of the metal nanoantenna is a regular triangle, a square or a regular hexagon; When the cross-section of the metal nanoantenna is an equilateral triangle or a regular hexagon, the array units are arranged in the shape of a regular hexagon, and when the cross-section of the metal nanoantenna is a regular hexagon, the number of metal nanoantennas included in the hexagonal structure is 1+6n, where n≥1 and n is an integer; When the cross section of the metal nanoantenna is a square, the array units are arranged in a square shape, and the number of metal nanoantennas included in the square structure is n*n, where n≥2, and n is an integer.

7. The epitaxial structure for a light absorber according to any one of claims 2 to 6, characterized in that: The nanoantenna array comprises at least two array units, and the period between two adjacent array units is p, p<λ0, p>2(a+s); and / or A plurality of array units are arranged in a regular triangle lattice or a square lattice to form the nanoantenna array.

8. The epitaxial structure for a light absorber according to claim 7, wherein: The thickness H of the first metal layer m The value range is H m ≥50nm, the thickness of the dielectric layer H s The value range is 50nm≤H s ≤λ0 / 2, and / or the thickness h of the second metal layer is in the range of 30nm≤h≤500nm; and / or, The thickness H of the dielectric layer s ≈λ0 / n eff , where n eff is the effective refractive index of the dielectric layer.

9. The epitaxial structure for a light absorber according to claim 7, wherein: The dielectric material is a material that is transparent when the working wavelength is the set wavelength λ0; and / or, The material of the dielectric layer is at least one of SiO2, TiO2, Al2O3 and MgF2.

10. A light absorber, characterized in that The epitaxial structure for a light absorber comprises the epitaxial structure for a light absorber according to any one of claims 1 to 9.

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