Metasurface multilayer nanotaper array cutoff absorber

Abstract

This invention discloses a metasurface multilayer nanocone array cutoff absorber in the field of optical metamaterials technology. It includes a quadrangular prism-pyramid array group grown on a silicon dioxide substrate. The quadrangular prism-pyramid array group comprises a bottom quadrangular prism, a quadrangular prism array formed on the top surface of the bottom quadrangular prism, and a quadrangular pyramid array formed on the top surface of the quadrangular prism array. Each quadrangular nanoprism in the quadrangular prism array consists of three layers of smaller quadrangular nanoprisms with gradually decreasing dimensions from bottom to top. The smaller quadrangular nanoprisms are all multilayer structures with alternating layers of titanium and indium phosphide. The quadrangular pyramid array consists of quadrangular pyramids formed on the top surface of each top layer of smaller quadrangular nanoprisms. The pyramids are made of lead sulfide. This invention effectively absorbs light in the green to mid-infrared band, thereby improving the sensitivity and response speed of the detector. This invention can be applied to the fields of optical communication and sensors.

Description

Technical Field

[0001] This invention relates to the field of optical metamaterials technology, and in particular to a cutoff absorber. Background Technology

[0002] Metamaterials are artificially designed composite materials possessing unique physical properties not found in nature. Metamaterials exhibit characteristics not found in nature during the interaction of electromagnetic waves and matter. Due to their unique electromagnetic properties, they have potential applications in many fields, including superlens imaging, acoustic focusing, optical cloaking, high-sensitivity sensors, solar energy absorption, and acoustic cloaking. In most applications, absorption losses in metamaterials typically degrade performance; however, for artificial light absorbers, absorption losses become useful, and metamaterial absorbers can be designed by adjusting the geometric parameters and shape of the metamaterial structure. A perfect absorber is an artificial structure or material capable of almost completely absorbing incident electromagnetic waves within a specific wavelength or frequency range. Its core lies in achieving efficient capture and dissipation of incident energy through carefully designed electromagnetic response characteristics, with near-zero reflection and transmission. Perfect absorbers have significant application value in optics, energy, and sensing. In recent years, metasurface nanostructures have attracted widespread attention due to their optical manipulation capabilities and multifunctionality in ultrathin optical applications. They are widely used in many fields, such as optical filtering, optical detection and sensing, optical signal processing, and optical imaging. Broadband perfect absorbers based on nanostructures have also been extensively studied and published.

[0003] In many applications, a clear absorption cutoff is required between the absorption band and the non-absorption band. The cutoff absorption efficiency can be expressed as the extinction ratio ER = 10*log (Aa / An) dB, where Aa is the minimum absorption within the absorption band and An is the maximum absorption within the non-absorption band; the extinction difference ED = Aa - An; and the cutoff slope CS = (Aa - An) / (λa - λn), where λa is the maximum wavelength / minimum wavelength within the absorption band and λn is the minimum wavelength / maximum wavelength within the non-absorption band. Ideally, ER, ED, and CS should be as large as possible. These works have made significant progress in the field of broadband absorbers, but they did not consider the cutoff efficiency, which is crucial in applications. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a metasurface multilayer nanocone array cutoff absorber that effectively absorbs light from the green to mid-infrared bands, thereby improving the sensitivity and response speed of the detector.

[0005] The objective of this invention is achieved as follows: a metasurface multilayer nanocone array cutoff absorber, comprising a quadrangular prism-pyramid array group grown on a silicon dioxide substrate, the quadrangular prism-pyramid array group comprising a bottom monolithic quadrangular prism, a quadrangular prism array formed on the top surface of the monolithic quadrangular prism, and a quadrangular pyramid array formed on the top surface of the quadrangular prism array; each quadrangular nanoprism in the quadrangular prism array consists of three layers of smaller quadrangular nanoprisms with gradually decreasing dimensions from bottom to top, with gaps between adjacent smaller quadrangular nanoprisms, the smaller quadrangular nanoprisms being a multilayer structure of alternating titanium and indium phosphide; the quadrangular pyramid array consists of quadrangular pyramids formed on the top surface of each top layer of smaller quadrangular nanoprisms, the quadrangular pyramids being made of lead sulfide.

[0006] Furthermore, the entire tetrahedron comprises six small layers, arranged in an alternating structure of titanium and indium phosphide from bottom to top; the lower two layers of small tetrahedron nanopillars in the tetrahedron array comprise six small layers, arranged in an alternating structure of titanium and indium phosphide from bottom to top; the top layer of small tetrahedron nanopillars comprises three small layers, arranged in an indium phosphide-titanium-indium phosphide structure from bottom to top.

[0007] Furthermore, the thickness of each small layer of titanium and indium phosphide in the entire tetragonal prism and in the tetragonal prism array is equal.

[0008] Furthermore, the length and width of the entire tetrahedron are consistent with the array period P, P=390-410 nm, and the thickness of each small layer of titanium and indium phosphide is h=50-90 nm.

[0009] Furthermore, in the quadrangular prism array, the side length of the bottom layer of small quadrangular nanopillars is a4 = 290-320 nm, the side length of the middle layer of small quadrangular nanopillars is a3 = 120-240 nm, the side length of the top layer of small quadrangular nanopillars is a2 = 60-140 nm, and the thickness of each small layer of titanium and indium phosphide is h = 50-90 nm.

[0010] Furthermore, the base side length of the square pyramid is a1 = 30-100 nm, and the height is h3 = 110-310 nm.

[0011] Furthermore, the length and width of the entire tetrahedron are consistent with the array period P, P=400nm, the thickness of each small layer of titanium and indium phosphide is h=70, the side length of the bottom layer of the tetrahedron array is a4=300nm, the side length of the middle layer of the small tetrahedron nanopillars is a3=160nm, the side length of the top layer of the small tetrahedron nanopillars is a2=100nm, the thickness of each small layer of titanium and indium phosphide is h=70nm, the side length of the base of the tetrahedron is a1=50nm, and the height is h3=210nm.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves an average absorption of 0.982 in the 500-5705 nm wavelength range, and an average absorption of only 0.052 in the non-absorption band of 11610 nm-30500 nm. The ER is 9.84 dB, ED is 0.862, and CS is 0.00015 nm. -1 In photodetectors, effective absorption of light in the green to mid-infrared band is necessary to generate sufficient photogenerated carriers, thereby improving the detector's sensitivity and response speed, and achieving efficient detection and conversion of optical signals. This invention effectively absorbs light in the green to mid-infrared band. In thermophotovoltaic systems, light radiation in the green to mid-infrared band needs to be absorbed and converted into heat energy, which is then converted into electrical energy through the thermophotovoltaic effect. Effective absorption helps improve the system's energy conversion efficiency, and this invention effectively absorbs light in the green to mid-infrared band. This invention can be applied to the fields of optical communication and sensors. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of the present invention (5×5 cycle).

[0015] Figure 2 This is a cross-sectional view of one cycle cut along the X-axis in this invention.

[0016] Figure 3 This is a cross-sectional view of one cycle of two adjacent small Ti / InP tetragonal prisms cut along the X-axis in one layer of the present invention.

[0017] Figure 4 This is the theoretical value of the absorption spectrum cutoff in the wavelength range of 500nm to 40000nm for this invention.

[0018] Figure 5 This is a schematic diagram illustrating the effect of parameter a1 on the overall absorption in this invention.

[0019] Figure 6 This is a schematic diagram illustrating the effect of parameter P on overall absorption in this invention.

[0020] Figure 7 This is a schematic diagram illustrating the effect of parameter a2 on the overall absorption in this invention.

[0021] Figure 8 This is a schematic diagram illustrating the effect of parameter a3 on the overall absorption in this invention.

[0022] Figure 9 This is a schematic diagram illustrating the effect of parameter a4 on the overall absorption in this invention.

[0023] Figure 10 This is a schematic diagram illustrating the effect of parameter h on overall absorption in this invention.

[0024] Figure 11 This is a schematic diagram illustrating the effect of parameter h3 on the overall absorption in this invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] like Figure 1-3 The illustrated metasurface multilayer nanocone array cutoff absorber includes a quadrangular prism-pyramid array group grown on a silicon dioxide substrate. The quadrangular prism-pyramid array group includes a bottom monolithic quadrangular prism, a quadrangular prism array formed on the top surface of the monolithic quadrangular prism, and a quadrangular pyramid array formed on the top surface of the quadrangular prism array. Each quadrangular nanoprism in the quadrangular prism array consists of three layers of small quadrangular nanoprisms with gradually decreasing size from bottom to top, with gaps between adjacent small quadrangular nanoprisms. The small quadrangular nanoprisms are all multilayer structures with alternating titanium and indium phosphide. The quadrangular pyramid array consists of quadrangular pyramids formed on the top surface of each top layer of small quadrangular nanoprisms. The quadrangular pyramids are made of lead sulfide (PbS).

[0027] Furthermore, the entire tetrahedron comprises six sub-layers, arranged in an alternating structure of titanium and indium phosphide from bottom to top; the lower two sub-layers of the tetrahedron array each comprise six sub-layers, arranged in an alternating structure of titanium and indium phosphide from bottom to top; the top sub-layers of the tetrahedron array each comprise three sub-layers, arranged in an indium phosphide-titanium-indium phosphide structure from bottom to top; the thickness of each sub-layer of titanium and indium phosphide in the entire tetrahedron and the tetrahedron array is equal, the height of each sub-layer of indium phosphide is h1, the height of each sub-layer of titanium is h2, and h1=h2=h.

[0028] To simultaneously maintain high absorption and sharp cutoff within the absorption band, the length and width of the entire tetrahedron are consistent with the array period P, where P = 390-410 nm. The side lengths of the small tetrahedron nanopillars in the bottom layer are a4 = 290-320 nm, the middle layer a3 = 120-240 nm, and the top layer a2 = 60-140 nm. The thickness of each small layer of titanium and indium phosphide is h = 50-90 nm. The base side length of the tetrahedron is a1 = 30-100 nm, and the height is h3 = 110-310 nm. The optimized parameters are h = 70 nm, h3 = 210 nm, a1 = 50 nm, a2 = 100 nm, a3 = 160 nm, a4 = 300 nm, and P = 400 nm.

[0029] Figure 4 The theoretical absorption spectra of the optimized structure are shown. The average absorption is 0.982 in the wavelength band (absorption band) between 500-5705 nm, decreasing sharply from 0.963 at 5705 nm to 0.1 at 11610 nm. In the non-absorption band (11610 nm-30500 nm), the average absorption is only 0.052. The extinction ratio is 9.84 dB, the extinction difference is 0.862, and the cutoff slope is 0.00015 nm. -1 .

[0030] Below, this invention uses the finite-difference time-domain (FDTD) method to study the physical mechanism of cutoff perfect absorption in the cutoff absorber, explores the allowable range of parameter errors in actual manufacturing, and uses the controlled variable method to change each geometric parameter in turn to study the influence of different geometric parameters on the working performance of the absorber.

[0031] With other simulation parameters remaining constant, the change in the structure's absorptivity to incident light as the width a1 changes is as follows: Figure 5 As shown. The simulation range set in this invention is from 30nm to 100nm, with a simulation step size of 10nm. (From...) Figure 5 It can be seen that when a1 changes, the absorption and cutoff performance in the absorption band do not change significantly. When a1 = 70 nm, the average absorption of the absorption band is 0.982, and the average absorption of the non-absorption band reaches its lowest point. In order to maintain both high absorption and sharp cutoff in the absorption band, this invention sets a1 = 70 nm in the cutoff perfect absorber, with an allowable range of 50-90 nm.

[0032] With other simulation parameters remaining constant, the change in the absorption rate of the structure to incident light as the array period P changes is as follows: Figure 6 As shown. The simulation range set in this invention is from 360nm to 520nm, with a simulation step size of 40nm. Figure 6It can be seen that when P deviates from 400 nm, the absorption of the absorption band decreases to varying degrees, with the average absorption decreasing from 0.982 to 0.923. Regarding the cutoff performance, while increasing P from 400 nm enhances the cutoff performance somewhat, the difference is not significant, and the absorption of the non-absorption bands shows little difference. Conversely, decreasing P from 400 nm weakens the cutoff performance, and the absorption of the non-absorption bands increases to varying degrees. To simultaneously maintain high absorption and sharp cutoff in the absorption band, this invention sets P = 400 nm in the cutoff perfect absorber, with an allowable range of 390-410 nm. Figure 7 The absorption spectra of different a2 values ​​are shown, which are consistent with... Figure 6 Having a similar trend of change, this invention will not discuss it further here. For similar reasons, this invention sets a2 = 100 nm, with an allowable range of 60-140 nm.

[0033] With other simulation parameters remaining constant, the change in the structure's absorptivity to incident light as the width a3 changes is as follows: Figure 8 As shown. The simulation range set in this invention is from 120nm to 280nm, with a simulation step size of 40nm. Figure 8 It can be seen that when a3 deviates from 160 nm, the absorption of the absorption band decreases to varying degrees, with the average absorption decreasing from 0.982 to 0.868. Regarding cutoff performance, when a3 increases from 160 nm, the cutoff performance weakens, and the absorption of the non-absorption band increases to varying degrees; when a3 decreases from 160 nm, although the cutoff performance is enhanced, the difference is not significant, and the absorption of the non-absorption band shows little difference. Similarly, to simultaneously maintain high absorption and sharp cutoff in the absorption band, this invention sets a3 = 160 nm in the cutoff perfect absorber, with an allowable range of 120-240 nm. Figure 9 The absorption spectra of different a4 values ​​are shown, which are consistent with... Figure 8 Similar variations exist, which will not be discussed further here. For similar reasons, this invention sets a4 = 300 nm, with an allowable range of 290-320 nm.

[0034] With other simulation parameters remaining constant, the change in the structure's absorptivity to incident light as the height h changes is as follows: Figure 10 As shown. The simulation range set in this invention is from 50nm to 90nm, with a simulation step size of 10nm. Figure 10 It can be seen that when h deviates from 70 nm, the absorption of the absorption band decreases to varying degrees, with the average absorption decreasing from 0.982 to 0.956. The cutoff performance also decreases to varying degrees, while the absorption of the non-absorption bands shows little difference. In order to maintain both high absorption and sharp cutoff in the absorption band, this invention sets h = 70 nm in the cutoff perfect absorber, with an allowable range of 50-90 nm.

[0035] With other simulation parameters remaining constant, the change in the structure's absorptivity to incident light as the height h3 changes is as follows: Figure 11 As shown. The simulation range set in this invention is from 110nm to 310nm, with a simulation step size of 50nm. (From...) Figure 11 It can be seen that when h3 changes, the absorption in the absorption band does not change significantly. Regarding the cutoff performance, when h3 increases from 210 nm, although the cutoff performance is slightly enhanced, the difference is not significant, and the absorption in the non-absorption bands increases to varying degrees; when h3 decreases from 210 nm, the cutoff performance weakens, and the absorption in the non-absorption bands shows little difference. To simultaneously maintain high absorption and sharp cutoff in the absorption band, this invention sets h3 = 210 nm in the cutoff perfect absorber, with an allowable range of 110-310 nm.

[0036] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A metasurface multilayer nanocone array cutoff absorber, characterized in that, The array includes a tetrahedral prism-pyramid array grown on a silicon dioxide substrate. The tetrahedral prism-pyramid array includes a bottom monolithic tetrahedral prism, a tetrahedral prism array formed on the top surface of the monolithic tetrahedral prism, and a tetrahedral pyramid array formed on the top surface of the tetrahedral prism array. Each tetrahedral nanopillar in the tetrahedral prism array consists of three layers of smaller tetrahedral nanopillars with gradually decreasing dimensions from bottom to top, with gaps between adjacent smaller tetrahedral nanopillars. The smaller tetrahedral nanopillars are all multilayer structures with alternating layers of titanium and indium phosphide. The tetrahedral pyramid array consists of tetrahedral pyramids formed on the top surface of each top layer of smaller tetrahedral nanopillars. The tetrahedral pyramids are made of lead sulfide.

2. The metasurface multilayer nanocone array cutoff absorber according to claim 1, characterized in that, The entire quadrangular prism comprises six small layers, arranged in an alternating structure of titanium and indium phosphide from bottom to top; the lower two layers of small quadrangular nanopillars in the quadrangular prism array comprise six small layers, arranged in an alternating structure of titanium and indium phosphide from bottom to top; the top layer of small quadrangular nanopillars comprises three small layers, arranged in an indium phosphide-titanium-indium phosphide structure from bottom to top.

3. The metasurface multilayer nanocone array cutoff absorber according to claim 2, characterized in that, In the entire tetrahedron, and in each small layer of titanium and indium phosphide in the tetrahedron array, the thickness is equal.

4. The metasurface multilayer nanocone array cutoff absorber according to claim 3, characterized in that, The length and width of the entire tetrahedron are consistent with the array period P, P=390-410 nm, and the thickness of each small layer of titanium and indium phosphide is h=50-90 nm.

5. A metasurface multilayer nanocone array cutoff absorber according to claim 4, characterized in that, The side length of the small four-sided nanopillars in the bottom layer of the array is a4 = 290-320 nm, the side length of the small four-sided nanopillars in the middle layer is a3 = 120-240 nm, the side length of the small four-sided nanopillars in the top layer is a2 = 60-140 nm, and the thickness of each small layer of titanium and indium phosphide is h = 50-90 nm.

6. The metasurface multilayer nanocone array cutoff absorber according to claim 5, characterized in that, The base side length of the square pyramid is a1 = 30-100 nm, and the height is h3 = 110-310 nm.

7. The metasurface multilayer nanocone array cutoff absorber according to claim 5, characterized in that, The length and width of the entire tetrahedron are consistent with the array period P, P=400nm. The thickness of each small layer of titanium and indium phosphide is h=70. The side length of the bottom layer of the tetrahedron array is a4=300nm, the side length of the middle layer of the small tetrahedron is a3=160nm, the side length of the top layer of the small tetrahedron is a2=100nm, the thickness of each small layer of titanium and indium phosphide is h=70nm, the side length of the base of the tetrahedron is a1=50nm, and the height is h3=210nm.

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