Long-wave and very long-wave infrared all-silicon antireflection super surface composition method and system

Abstract

The application provides a long-wave and very long-wave infrared full-silicon anti-reflection super surface composition method and system, comprising the following steps: S1, collecting optical information of high-purity silicon material; S2, obtaining complex refractive index parameters of the high-purity silicon material according to the optical information; S3, establishing a super surface model according to the complex refractive index parameters; S4, obtaining a reflectivity curve of a high-purity silicon column structure based on the super surface model; S5, obtaining average reflectivity according to the reflectivity curve and selecting physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; and periodically arranging the physical parameters on a high-purity silicon substrate to form a target super surface. The high-purity silicon column structure and the high-purity silicon substrate are made of the same material, so that the problem of thermal stress mismatch and easy falling caused by the introduction of a new material is avoided, and the detector can be adapted to normal temperature and low temperature working.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metasurfaces, and particularly relates to a long-wave and very long-wave infrared all-silicon antireflection metasurface composition method and system. BACKGROUND

[0002] Infrared detectors working in long-wave and very long-wave infrared, i.e., infrared with a wavelength of 8-28 microns, have very important applications in the field of remote sensing, such as the James Webb telescope used for astronomical exploration, in which infrared instruments are equipped with long-wave and very long-wave detectors for exploring the origin of the universe, etc.

[0003] The semiconductor material commonly used in such detectors has a high refractive index, so when infrared radiation is incident at the interface between air and the detector, strong reflection occurs, thereby reducing the core technical indicators such as the response and sensitivity of the detector. Taking the blocked impurity band (BIB) detector equipped on the infrared instrument as an example, the radiation signal passes through the first interface, which is the air-high-purity silicon substrate interface, in which the refractive index n air of air is 1, and the refractive index n si of the ideal high-purity silicon substrate is 3.42, with a large difference between the two. According to the Fresnel equation, the reflection on the single-layer interface is 30%.

[0004] Therefore, antireflection technology is often used to reduce the surface reflection of such detectors. The commonly used antireflection technology currently adopts a multi-layer optical thin film method, and to achieve effective antireflection, the thickness h of the thin film is determined by the wavelength λ and the refractive index n of the thin film material, and the three satisfy the relationship: h = λ / (n x 4). For long-wave and very long-wave infrared, h is usually in the order of microns, but thicker films are prone to falling off during processing, and there is also thermal stress between the multi-layer films. Therefore, the antireflection technology based on multi-layer thin films has great difficulty and limitations in the long-wave and very long-wave infrared band.

[0005] As a kind of artificial micro-nano structure, metasurfaces can flexibly control light waves on a subwavelength scale. With the development of metasurface technology, introducing metasurfaces on the surface of a device can also achieve optical antireflection. When long-wave and very long-wave infrared radiation is incident, it first interacts with the micro-nano structure on the surface of the device, so by designing a matching micro-nano structure, the coupling efficiency of the incident light and the metasurface can be increased, thereby coupling more radiation light to the functional layer of the device to achieve effective antireflection and ultimately improve the performance of the device. SUMMARY

[0006] In view of the defects in the prior art, the purpose of the present application is to provide a long-wave and very long-wave infrared all-silicon antireflection metasurface composition method and system.

[0007] A long-wave and very long-wave infrared all-silicon antireflection super surface composition method is provided according to the application, comprising:

[0008] Step S1: collecting optical information of high-purity silicon material;

[0009] Step S2: calculating complex refractive index parameters of the high-purity silicon material according to the optical information;

[0010] Step S3: establishing a super surface model according to the complex refractive index parameters;

[0011] Step S4: obtaining a reflectivity curve of high-purity silicon column structure based on the super surface model;

[0012] Step S5: obtaining average reflectivity according to the reflectivity curve and selecting physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; arranging the physical parameters periodically on a high-purity silicon substrate to form a target super surface.

[0013] Preferably, in the step S1, the optical information is a transmission curve, a reflection curve and an absorption curve of the high-purity silicon material in the long-wave and very long-wave infrared waveband;

[0014] The mathematical expressions of the reflection curve, the absorption curve and the transmission curve are as follows from top to bottom:

[0015]

[0016] wherein, T exp represents the transmission curve; R0 represents single-interface reflectivity; a0 represents high-purity silicon substrate absorption rate; R exp represents the reflection curve; A exp represents the absorption curve.

[0017] Preferably, in the step S2, the complex refractive index parameters include a real part of complex refractive index and an imaginary part of complex refractive index; the real part of complex refractive index is refractive index, and the imaginary part of complex refractive index is extinction coefficient;

[0018] The mathematical expression of the refractive index is as follows:

[0019]

[0020] wherein, R0 represents single-interface reflectivity; n si represents high-purity silicon substrate refractive index; n air represents air refractive index;

[0021] The mathematical expression of the extinction coefficient is as follows:

[0022]

[0023] Wherein, a0 represents high-purity silicon substrate absorption rate, ω represents angular frequency; z represents uniform medium thickness; k represents extinction coefficient; e represents natural constant; c represents light speed.

[0024] Preferably, in the step S4, the size of the high-purity silicon column structure should satisfy the expression:

[0025]

[0026] Wherein, n eff represents refractive index, n si represents high-purity silicon substrate refractive index; n air represents air refractive index;

[0027]

[0028] Wherein, h represents thickness; λ represents wavelength;

[0029] Preferably, in the step S5, it includes:

[0030] Step S5.1: Calculate the reflectivity curve of different periods P, different side lengths L and different thickness h by finite difference time domain method, and form a parameter group with the calculation results;

[0031] Step S5.2: According to the parameter group, evaluate and obtain the average reflectivity;

[0032] Step S5.3: Select the physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; arrange the physical parameters periodically on the high-purity silicon substrate;

[0033] Step S5.4: Based on the high-purity silicon substrate, cooperate with the single-sided surface periodic distribution of high-purity silicon column structure to form a target metasurface;

[0034] In the step S5.2, the mathematical expression of the average reflectivity is:

[0035]

[0036] Wherein, R avg represents average reflectivity, λ i represents wavelength point, r i is the reflectivity corresponding to the wavelength point, λ1=8μm, λ n =28μm.

[0037] According to the long-wave and very long-wave infrared all-silicon antireflection metasurface composition system provided by the application, comprising:

[0038] Module M1: Collect optical information of high-purity silicon material;

[0039] Module M2: obtaining a complex refractive index parameter of the high-purity silicon material according to the optical information;

[0040] Module M3: establishing a metasurface model according to the complex refractive index parameter;

[0041] Module M4: obtaining a reflectivity curve of a high-purity silicon column structure based on the metasurface model;

[0042] Module M5: obtaining an average reflectivity according to the reflectivity curve and selecting a physical parameter of the high-purity silicon column structure corresponding to a minimum average reflectivity; arranging the physical parameter periodically on a high-purity silicon substrate to form a target metasurface.

[0043] Preferably, in the module M1, the optical information includes a transmission curve, a reflection curve and an absorption curve of the high-purity silicon material in the long-wave and very long-wave infrared wave bands.

[0044] The mathematical expressions of the reflection curve, the absorption curve and the transmission curve are as follows from top to bottom:

[0045]

[0046] wherein, T exp represents the transmission curve; R0 represents a single-interface reflectivity; a0 represents a high-purity silicon substrate absorption rate; R exp represents the reflection curve; A exp represents the absorption curve.

[0047] Preferably, in the module M2, the complex refractive index parameter includes a real part of the complex refractive index and an imaginary part of the complex refractive index; the real part of the complex refractive index is a refractive index, and the imaginary part of the complex refractive index is an extinction coefficient.

[0048] The mathematical expression of the refractive index is as follows:

[0049]

[0050] wherein, R0 represents a single-interface reflectivity; n si represents a high-purity silicon substrate refractive index; n air represents an air refractive index.

[0051] The mathematical expression of the extinction coefficient is as follows:

[0052]

[0053] wherein, a0 represents a high-purity silicon substrate absorption rate, ω represents an angular frequency; z represents a uniform medium thickness; k represents an extinction coefficient; e represents a natural constant; and c represents a light speed.

[0054] Preferably, in the module M4, the size of the high-purity silicon column structure should satisfy the expression:

[0055]

[0056] Wherein, n eff represents the refractive index, n si represents the refractive index of the high-purity silicon substrate; n air represents the refractive index of air;

[0057]

[0058] Wherein, h represents the thickness; and λ represents the wavelength.

[0059] Preferably, in the module M5, the following is included:

[0060] Module M5.1: Calculate the reflectivity curve of different periods P, different side lengths L and different thicknesses h by the finite difference time domain method, and let the calculation results form a parameter group;

[0061] Module M5.2: According to the parameter group, evaluate and obtain the average reflectivity;

[0062] Module M5.3: Select the physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; and arrange the physical parameters periodically on the high-purity silicon substrate;

[0063] Module M5.4: Based on the high-purity silicon substrate, cooperate with the high-purity silicon column structure periodically distributed on one side of the surface to form a target metasurface;

[0064] In the module M5.2, the mathematical expression of the average reflectivity is:

[0065]

[0066] Wherein, R avg represents the average reflectivity, λ i represents the wavelength point, r i is the reflectivity corresponding to the wavelength point, λ1=8μm, λ n =28μm.

[0067] Compared with the prior art, the present application has the following beneficial effects:

[0068] 1. The metasurface anti-reflection technology provided by the present application has a wide working bandwidth and low manufacturing cost.

[0069] 2. The full-silicon anti-reflection metasurface provided by the present application can be directly integrated with the detector silicon substrate, reducing the processing complexity and being conducive to the integrated development of devices.

[0070] 3、The high-purity silicon column structure is of the same material as the high-purity silicon substrate, avoids the problem of thermal stress mismatch and easy falling caused by introduction of a new material, and can be adapted to a detector working at normal temperature and low temperature. BRIEF DESCRIPTION OF DRAWINGS

[0071] Other features, objects, and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments, when read in conjunction with the accompanying drawings:

[0072] Figure 1 A three-dimensional schematic view (left) and a top view (right) of a long-wave and very long-wave infrared full-silicon antireflection super surface unit structure provided by the application; the high-purity silicon column is a square column;

[0073] Figure 2 A multi-layer interface transmission model schematic diagram when measuring the transmission and reflection curve of high-purity silicon provided by the application;

[0074] Figure 3 A multi-layer interface transmission model schematic diagram when measuring the transmission and reflection curve of high-purity silicon provided by the application;

[0075] Figure 4 A complex refractive index curve of high-purity silicon material provided by the application, wherein n and k represent the real part of the complex refractive index, i.e., the refractive index, and the imaginary part of the complex refractive index, i.e., the extinction coefficient;

[0076] Figure 5 A schematic diagram of the average reflectivity of the high-purity silicon square column structure in the long-wave and very long-wave infrared waveband under different parameter groups provided by the application;

[0077] Figure 6 A schematic diagram of the optimal reflection curve of the high-purity silicon square column structure in the long-wave and very long-wave infrared waveband and the reflection curve of the high-purity silicon single-layer surface provided by the application;

[0078] Figure 7 A normalized electric field intensity distribution result on the y=0 μm plane at different times provided by the application; wherein a) is the electric field intensity distribution on the y=0 μm plane when the infrared pulsed light source is incident into the air and has not yet interacted with the super surface; b) is the electric field intensity distribution on the y=0 μm plane when the infrared pulsed light source interacts with the super surface; c) is the electric field intensity distribution on the y=0 μm plane after the infrared pulsed light source interacts with the super surface. DETAILED DESCRIPTION

[0079] The application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the application. These are within the scope of protection of the application.

[0080] The long-wave and very long-wave infrared all-silicon antireflection super surface of the embodiment of the application can reduce the reflection of incident long-wave and very long-wave infrared light beams and increase the transmission of long-wave and very long-wave infrared light beams, filling the blank of all-silicon antireflection super surfaces in the long-wave and very long-wave infrared waveband. Integrating the application on a detector can reduce the strong reflection that occurs when infrared radiation is incident to the interface between air and the detector, thereby improving the core technical indicators of the detector, such as response and sensitivity. The existing antireflection technology adopts a multilayer film mode, which has the problems of narrow bandwidth and easy to fall off; in comparison, directly processing a silicon column structure of the same material as the substrate on the high-purity silicon substrate of the detector is more conducive to the realization of a wide bandwidth and the integration application.

[0081] Step one: test the transmission, reflection and absorption curves of high-purity silicon material in the long-wave and very long-wave infrared waveband;

[0082] Step two: according to the actual measurement, use a multilayer interface transmission and reflection model to calculate the real part of the complex refractive index of the material, that is, the refractive index n and the imaginary part of the complex refractive index, that is, the extinction coefficient k;

[0083] Step three: the high-purity silicon material parameters in the super surface simulation use the calculated complex refractive index, and an all-silicon super surface model is established in the simulation software according to the equivalent homogeneous medium theory;

[0084] Step four: the simulation calculation obtains the reflectivity curves of high-purity silicon column structures of different sizes when long-wave and very long-wave infrared light beams are incident;

[0085] Step five: calculate the average reflectivity of high-purity silicon column structures of different sizes in the long-wave and very long-wave infrared waveband, and select the corresponding silicon column physical parameters under the condition of the minimum average reflectivity, and arrange them in the high-purity silicon substrate;

[0086] The long-wave and very long-wave infrared all-silicon antireflection super surface is composed of a high-purity silicon substrate and a high-purity silicon column structure periodically distributed on one side of the surface of the high-purity silicon substrate.

[0087] Specifically, the period of the high-purity silicon column structure should be less than one-fifth of the maximum working wavelength.

[0088] Specifically, the periodic high-purity silicon column structure can be regarded as an equivalent medium.

[0089] Specifically, the height of the high-purity silicon column structure and the two side media depend on the refractive index of high-purity silicon and air and the wavelength.

[0090] The present invention designs a long-wave and very long-wave infrared all-silicon anti-reflection metasurface composed of a high-purity silicon substrate and a high-purity silicon pillar structure periodically distributed on one side of the substrate, thereby achieving the functions of reducing the reflectivity of incident long-wave and very long-wave infrared beams and increasing the transmittance of long-wave and very long-wave infrared beams.

[0091] In this embodiment of the invention, the high-purity silicon pillar structure is a square pillar, and the long-wave and very long-wave infrared band is 8-28μm.

[0092] The entire metasurface is made of high-purity silicon; therefore, accurate parameters of the high-purity silicon material are required before subsequent simulations of the all-high-purity silicon metasurface can be performed. During actual testing on the high-purity silicon substrate, the infrared beam passes sequentially through air-high-purity silicon-air material, such as... Figure 3 As shown, there are two interfaces at this point, therefore the measured transmission T exp Reflection R exp and absorption of A exp The curve represents the effect after multiple transmission, reflection, and absorption superpositions. Assuming the reflectivity R0 of the air-high-purity silicon single interface and the absorptivity a0 of the high-purity silicon substrate with thickness h0, then according to the multilayer interface transmission-reflection model, the measured reflection curve R... exp Absorption curve A exp With transmission curve T exp The expressions are as follows:

[0093]

[0094] Among them, T exp The transmission curve is represented by R0; the single-interface reflectance is represented by a0; the absorptivity of the high-purity silicon substrate is represented by R. exp Represents the reflection curve; A exp This represents the absorption curve.

[0095] According to formula (1), R0(λ) and α0(λ) at different wavelengths can be solved by programming in Matlab software.

[0096] According to Fresnel's equations, the mathematical expression for the relationship between reflectivity and refractive index at a single-layer interface is:

[0097]

[0098] Where R0 represents the reflectivity of a single interface; n si Indicates the refractive index of a high-purity silicon substrate; n air Indicates the refractive index of air;

[0099] According to the Beer-Lambert Law, the light intensity I(z) after light with angular frequency ω and light intensity I0 passes through a homogeneous medium is related to the extinction coefficient k and the thickness z of the homogeneous medium, and the mathematical expression is:

[0100]

[0101] Where I(z) is the light intensity after passing through a homogeneous medium; I0 represents the light intensity; ω represents the angular frequency; z represents the thickness of the homogeneous medium; k represents the extinction coefficient; e represents the natural constant; and c represents the speed of light.

[0102] The absorptivity a0 of the high-purity silicon substrate can be expressed by formula (3):

[0103]

[0104] Therefore, based on the measured transmission T exp Reflection R exp and absorption of A exp The curve can be used to calculate R0 and a0 using formula (1), and then the refractive index n and extinction coefficient k of the high-purity silicon material can be calculated using formulas (2) and (4). The derived refractive index n and extinction coefficient k of the material are as follows: Figure 4 As shown. The calculated complex refractive index is imported into simulation software for subsequent design of long-wavelength and very long-wavelength infrared all-silicon anti-reflective metasurfaces.

[0105] like Figure 1 As shown, a single high-purity silicon square pillar structure is placed on a high-purity silicon substrate to form a metasurface unit. The unit structure has a period of P, a side length of L, and a thickness of h.

[0106] When the period P is less than one-fifth of the maximum operating wavelength, the high-purity silicon pillar structure is relatively small compared to the wavelength, and the high-purity silicon pillar structure layer can be regarded as an equivalent homogeneous medium. The equivalent refractive index n of the equivalent homogeneous medium layer can be changed by altering the dimensions of the high-purity silicon pillar structure. eff .

[0107] To reduce reflection, the dimensions of high-purity silicon pillar structures should meet the following conditions:

[0108]

[0109] Where, n eff n represents the refractive index. si Indicates the refractive index of a high-purity silicon substrate; n air Indicates the refractive index of air; the symbol "·" represents the multiplication sign;

[0110]

[0111] Where h represents thickness; λ represents wavelength;

[0112] Since the long-wave and very long-wave infrared waveband of the embodiment of the present application is 8-28 μm, the waveband range is wide, and different physical parameters of the high-purity silicon column structure need to be swept, and then the average reflectivity R avg of the 8-28 μm range is selected again.

[0113] On the basis of the derived complex refractive index of the high-purity silicon material, the reflectivity curves of different periods P, different side lengths L, and different thicknesses h are calculated by using the Finite Difference Time Domain (FDTD) method. Due to the processing limitation, the minimum line width is set to be no less than 2 μm, and therefore, the sweep step of the thickness h is set to be 0.1 μm, and the sweep range is 2.5-3.5 μm; the sweep step of the side length L is set to be 0.1 μm, and the sweep range is 3.2-4.5 μm; the distance between the period P and the side length L is set to be 2 μm, and there are 154 groups of parameter sets.

[0114] Since the calculation result is the reflectivity scatter r(λ) in the 8-28 μm waveband varying with the wavelength under different parameter sets, the average reflectivity R avg should be evaluated by first integrating r(λ) with respect to the wavelength in the waveband range and then dividing by the wavelength range, and the calculation formula is as follows:

[0115]

[0116] wherein R avg represents the average reflectivity, r i represents the reflectivity corresponding to the wavelength point λ i , λ1=8 μm, and λ n =28 μm.

[0117] The calculated average reflectivity of the high-purity silicon square column structure in the long-wave and very long-wave infrared waveband under different parameter sets is shown in FIG. Figure 5 The minimum average reflectivity of the metasurface in the 8-28 μm waveband is 4.2%, and the optimal parameter set is a period P=5.4 μm, a side length L=3.4 μm, and a thickness h=3 μm.

[0118] As shown in FIG. Figure 6 , the reflectivity curve of the metasurface under the optimal parameter set is lower than 10% in most wavebands in the 8-28 μm range, while the reflectivity of the high-purity silicon single-layer surface is about 30%.

[0119] In the simulation, an electric field monitor is set to observe the normalized total electric field intensity distribution on the y=0 μm plane at different times. Figure 7 a), b), and c) of FIG. 1 are arranged in time sequence, and completely embody the electric field intensity distribution of the three processes of the infrared pulsed light source from air incidence, interaction with the high-purity silicon column structure layer, and transmission through the high-purity silicon structure layer. From the simulation results, it can be seen that the metasurface has a very low reflectivity in the 8-28 μm waveband, and the optimal parameter set is a period P=5.4 μm, a side length L=3.4 μm, and a thickness h=3 μm.Figure 7 It can be seen that, after the infrared pulsed light source interacts with the high-purity silicon column structure layer, only a small amount of light source is reflected into the air, and most of the light source enters the high-purity silicon substrate layer.

[0120] Therefore, the all-silicon antireflection super surface designed by the embodiment of the present application can realize the function of reducing the reflection of infrared light beams in a wide band of 8-28 mu m, and the average reflectivity in the wide band is 4.2%.

[0121] The present application also provides a long-wave and very long-wave infrared all-silicon antireflection super surface composition system, which can be realized by executing the flow steps of the long-wave and very long-wave infrared all-silicon antireflection super surface composition method, that is, the long-wave and very long-wave infrared all-silicon antireflection super surface composition method can be understood as the preferred embodiment of the long-wave and very long-wave infrared all-silicon antireflection super surface composition system by those skilled in the art.

[0122] According to the present application, a long-wave and very long-wave infrared all-silicon antireflection super surface composition system is provided, which comprises:

[0123] Module M1: collecting optical information of high-purity silicon material;

[0124] Module M2: calculating the complex refractive index parameters of the high-purity silicon material according to the optical information;

[0125] Module M3: establishing a super surface model according to the complex refractive index parameters;

[0126] Module M4: obtaining the reflectivity curve of the high-purity silicon column structure based on the super surface model;

[0127] Module M5: obtaining the average reflectivity according to the reflectivity curve and selecting the physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; arranging the physical parameters periodically on the high-purity silicon substrate to form a target super surface.

[0128] Those skilled in the art know that, in addition to implementing the system and each device, module and unit thereof provided by the present application in the form of pure computer readable program code, the same functions can also be realized by logically programming the method steps in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers and embedded microcontrollers, etc. Therefore, the system and each device, module and unit thereof provided by the present application can be considered as a hardware component, and the devices, modules and units included therein for realizing various functions can also be considered as structures within the hardware component; the devices, modules and units for realizing various functions can also be considered as both software modules realizing methods and structures within hardware components.

[0129] In the description of the present application, it needs to be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0130] The specific embodiments of the present application are described above. It needs to be understood that the present application is not limited to the above specific embodiments, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application. The embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other without conflict.

Claims

1. A long-wave and very long-wave infrared all-silicon antireflection super surface composition method, characterized in that, The method comprises the following steps: Step S1: collecting optical information of high-purity silicon material; Step S2: obtaining complex refractive index parameters of the high-purity silicon material according to the optical information; Step S3: establishing a metasurface model according to the complex refractive index parameters; Step S4: obtaining reflectivity curves of high-purity silicon column structures based on the metasurface model; Step S5: obtaining average reflectivity according to the reflectivity curves and selecting physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; and periodically arranging the physical parameters on a high-purity silicon substrate to form a target metasurface. In the step S4, the size of the high-purity silicon column structure should satisfy the expression: where n eff represents the refractive index, n si represents the refractive index of the high-purity silicon substrate; n air represents the refractive index of air; Wherein, h represents thickness; and λ represents wavelength. In the step S5, the method comprises the following steps: Step S5.1: calculating reflectivity curves of different periods P, different side lengths L and different thicknesses h by using a finite-difference time-domain method, and forming a parameter group with the calculation results; Step S5.2: evaluating and obtaining average reflectivity according to the parameter group; Step S5.3: selecting physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; and periodically arranging the physical parameters on a high-purity silicon substrate; Step S5.4: forming a target metasurface based on the high-purity silicon substrate and in combination with the high-purity silicon column structure with a periodically distributed single-sided surface. In the step S5.2, the mathematical expression of the average reflectivity is: wherein R avg represents the average reflectivity, λ i represents the wavelength point, r i is the reflectivity corresponding to the wavelength point, λ1=8 μm, λ n =28 μm.

2. The long-wave and very long-wave infrared all-silicon antireflective metasurface composition method according to claim 1, characterized in that, In the step S1, the optical information is a transmission curve, a reflection curve and an absorption curve of the high-purity silicon material in a long-wave and very long-wave infrared wave band. The mathematical expressions of the reflection curve, the absorption curve and the transmission curve are as follows from top to bottom: wherein T exp represents a transmission curve; R0 represents a single interface reflectivity; a0 represents a high purity silicon substrate absorption; R exp represents a reflection curve; A exp represents an absorption curve.

3. The long-wave and very long-wave infrared all-silicon antireflective metasurface composition method according to claim 2, characterized in that, In the step S2, the complex refractive index parameters comprise a real part of complex refractive index and an imaginary part of complex refractive index; the real part of the complex refractive index is a refractive index, and the imaginary part of the complex refractive index is an extinction coefficient. The mathematical expression of the refractive index is: wherein R0represents a single interface reflectivity; n si represents a refractive index of a high-purity silicon substrate; n air represents a refractive index of air; The mathematical expression of the extinction coefficient is: Wherein, a0 represents high-purity silicon substrate absorption, ω represents angular frequency; z represents uniform medium thickness; k represents extinction coefficient; e represents natural constant; and c represents light speed.

4. A long-wave and very long-wave infrared all-silicon antireflective metasurface composition system, characterized in that, The method comprises the following steps: Module M1: collecting optical information of high-purity silicon material; Module M2: obtaining complex refractive index parameters of the high-purity silicon material according to the optical information; Module M3: establishing a metasurface model according to the complex refractive index parameters; Module M4: obtaining reflectivity curves of high-purity silicon column structures based on the metasurface model; Module M5: obtaining average reflectivity according to the reflectivity curves and selecting physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; Periodically arranging the physical parameters on a high-purity silicon substrate to form a target metasurface. In the module M4, the size of the high-purity silicon column structure should satisfy the expression: where n eff represents the refractive index, n si represents the refractive index of the high-purity silicon substrate; n air represents the refractive index of air; Wherein, h represents thickness; and λ represents wavelength. In the module M5, the method comprises the following steps: Module M5.1: calculating reflectivity curves of different periods P, different side lengths L and different thicknesses h by using a finite-difference time-domain method, and forming a parameter group with the calculation results; Module M5.2: evaluating and obtaining average reflectivity according to the parameter group; Module M5.3: selecting physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; and periodically arranging the physical parameters on a high-purity silicon substrate. Module M5.3: select the physical parameters of the high-purity silicon column structure corresponding to the minimum average reflectivity; arrange the physical parameters periodically on the high-purity silicon substrate; Module M5.4: based on the high-purity silicon substrate, cooperate with the high-purity silicon column structure with periodic distribution of single-sided surface to form a target metasurface; In the module M5.2, the mathematical expression of the average reflectivity is: wherein R avg represents the average reflectivity, λ i represents the wavelength point, r i is the reflectivity corresponding to the wavelength point, λ1= 8 μm, λ n = 28 μm.

5. The long- and very long-wave infrared all-silicon antireflective metasurface composition system according to claim 4, characterized in that, In the module M1, the optical information, that is, the transmission curve, reflection curve and absorption curve of high-purity silicon material in long-wave and very long-wave infrared wave band; The mathematical expressions of the reflection curve, absorption curve and transmission curve from top to bottom are: where T exp represents a transmission curve; R0 represents a single interface reflectivity; a0 represents a high purity silicon substrate absorption; R exp represents a reflection curve; A exp represents an absorption curve.

6. The long- and very long-wave infrared all-silicon antireflective metasurface composition system of claim 5, wherein, In the module M2, the complex refractive index parameters include the real part of the complex refractive index and the imaginary part of the complex refractive index; the real part of the complex refractive index is the refractive index, and the imaginary part of the complex refractive index is the extinction coefficient; The mathematical expression of the refractive index is: wherein R0represents the single interface reflectivity; n si represents the refractive index of the high-purity silicon substrate; n air represents the refractive index of air; The mathematical expression of the extinction coefficient is: Wherein, a0 represents the absorption rate of high-purity silicon substrate, ω represents the angular frequency; z represents the thickness of the uniform medium; k represents the extinction coefficient; e represents the natural constant; c represents the speed of light.

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