Ultra-wideband metasurface design method, ultra-wideband metasurface preparation method and ultra-wideband metasurface
Through inverse algorithm design and laser processing technology, the structural parameters of the metasurface unit are determined to achieve ultra-wideband high transmittance, solving the problem of efficiency decline in existing technologies and meeting the needs of various optical applications.
Patent Information
- Application Number
- CN202511133320.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-13
- Publication Date
- 2025-09-16
AI Technical Summary
The efficiency of existing metasurfaces decreases when they deviate from the designed central wavelength, making it difficult to achieve ultra-wideband high transmittance, resulting in large light transmission losses and an inability to meet usage requirements.
The first and second structural parameters of the metasurface unit structure are determined through an inverse algorithm. Combined with the target wavelength range and transmittance, an ultra-wideband metasurface is designed. Laser processing technology is used to process the nanopore structure inside the transparent medium to achieve high absolute efficiency.
The bandwidth of the metasurface is improved, the light transmission loss is reduced, and the usage requirements of various optical application scenarios are met.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of optical devices, and in particular to an ultra-wideband metasurface design method, a preparation method, and an ultra-wideband metasurface. Background Art
[0002] The use of low-loss materials such as HfO2, TiO2, and Si enables the realization of high-efficiency metasurfaces in various wavelength bands. However, their efficiency typically drops rapidly when deviating from the designed center wavelength. To address this issue, a variety of solutions have been developed to achieve broadband, high-efficiency metasurfaces. For example, the use of a quasi-continuous catenary structure can effectively solve the bandwidth limitation problem caused by resonance in traditional discrete structure metasurfaces. The use of dispersion engineering for unit structure design, which ensures that each structure has almost identical dispersion characteristics, can also achieve the expansion of the metasurface bandwidth.
[0003] However, the relative bandwidth of these implementations (the ratio of bandwidth to central wavelength when efficiency exceeds 90%) is typically less than 50%, and most of them are relative efficiencies (the ratio of the energy of modulated light in the outgoing light to the total energy of the outgoing light). Due to factors such as resonant absorption and scattering losses in the unit structure, metasurfaces struggle to achieve high transmittance over ultra-wideband, meaning they struggle to achieve high absolute efficiency (the ratio of the energy of modulated light in the outgoing light to the total energy of the incident light, calculated by multiplying the relative efficiency and transmittance). Consequently, light losses through metasurfaces are significant, making them unsuitable for current applications. Summary of the Invention
[0004] In view of this, the purpose of the embodiments of the present application is to provide an ultra-wideband metasurface design method, a preparation method and an ultra-wideband metasurface, so as to improve the problem of poor broadband control effect of metasurfaces existing in the prior art.
[0005] In order to solve the above problems, in a first aspect, an embodiment of the present application provides a method for designing an ultra-wideband metasurface, the method comprising: According to the target wavelength range and the target relative efficiency, the first structural parameters of the unit structure in the metasurface are determined based on an inverse algorithm; determining a second structural parameter of the unit structure according to the target wavelength range and the target transmittance; The structure of the metasurface includes a plurality of unit structures determined based on the first structural parameters and the second structural parameters.
[0006] In the above implementation process, the target wavelength range and target relative efficiency for the metasurface are first determined. An inverse algorithm is then used to determine the first structural parameters of the unit structures within the metasurface. Based on the target wavelength range and the target transmittance that the metasurface needs to achieve, the second structural parameters of the unit structures are then determined. The first and second structural parameters are then used to determine the actual structure of the unit structures, resulting in an ultra-wideband metasurface. By using an inverse design method to determine the first structural parameters and combining them with the second structural parameters to determine a unit structure that is applicable to the target wavelength range and can achieve the target relative efficiency and target transmittance, the bandwidth of the designed metasurface is effectively increased, achieving high absolute efficiency for ultra-wideband applications, reducing light loss through the metasurface, and meeting the requirements of a variety of current optical application scenarios.
[0007] Optionally, the first structural parameter includes: a target number of stacked layers of the unit structure, a target rotation angle generated by each unit structure based on a reference angle, and a target phase delay amount of each unit structure; The second structural parameters include: a target number and a target diameter of nanopore structures in the unit structure.
[0008] In the above implementation, the first structural parameters include spatial structural parameters such as the target number of unit structure stacking layers, the target rotation angle of each unit structure based on a reference angle, and the target phase delay of each unit structure. Ultra-wideband dispersion compensation is achieved through the target rotation angle, ensuring that each wavelength within the ultra-wideband range has the same target phase delay, thereby achieving a high target relative efficiency. Second structural parameters include structural parameters such as the target number and target diameter of the nanopore structures provided in the unit structure. Design considerations include the stacking, relative positioning, functionality of the multiple unit structures, and the specific structure within each unit structure, effectively improving the functional reliability of the resulting unit structure.
[0009] Optionally, the influence factor of each unit structure on the incident light is determined based on the rotation angle, phase delay, thickness and equivalent refractive index of the unit structure for different polarized lights.
[0010] In the above implementation process, during the design process, the influence factor of the unit structure on the incident light can be determined based on the rotation angle, phase delay, thickness and equivalent refractive index of the unit structure for different polarized light, so as to design various structural parameters of the unit structure in combination with the influence factors, so that the unit structure can achieve the target relative efficiency and target transmittance in the application scenario of the target wavelength range, so that the designed metasurface can achieve ultra-wideband high absolute efficiency.
[0011] Optionally, determining the first structural parameters of the unit structure in the metasurface based on an inverse algorithm according to the target wavelength range and the target relative efficiency includes: Determining the target wavelength range and the target relative efficiency according to functional requirements corresponding to the metasurface; Based on the inverse algorithm, calculation is performed according to the target wavelength range and the target relative efficiency to determine the first structural parameters that meet the target relative efficiency within the target wavelength range; The inverse algorithm includes at least one of a particle swarm algorithm, a simulated annealing method, a genetic algorithm, and deep learning.
[0012] In the above implementation process, the target wavelength range applicable to the metasurface and the target relative efficiency that the metasurface needs to achieve can be determined based on the functional requirements corresponding to the metasurface. Then, through various types of inverse algorithms, calculations are performed based on the target wavelength range and the target relative efficiency to determine the first structural parameters that can meet the target relative efficiency within the target wavelength range, effectively improving the effectiveness of the first structural parameters to improve the functional reliability of the unit structure.
[0013] Optionally, determining the second structural parameter of the unit structure according to the target wavelength range and the target transmittance includes: Determining the target wavelength range and the target transmittance according to functional requirements corresponding to the metasurface; The second structural parameter is determined according to the target transmittance and a transmittance formula of the nanopore structure in the unit structure in combination with the target wavelength range.
[0014] In the above implementation process, the target wavelength range applicable to the metasurface and the target transmittance that the metasurface needs to achieve can be determined based on the functional requirements corresponding to the metasurface. Then, based on the target transmittance and the transmittance formula of the nanopore structure in the unit structure, the second structural parameter that can achieve the target transmittance within the target wavelength range is determined, which effectively improves the effectiveness of the second structural parameter and thus improves the functional reliability of the unit structure.
[0015] Optionally, the transmittance formula is determined based on the energy of the outgoing light, the energy of the incident light, the number of the nanopore structures, and the scattering cross section of the nanopore structures.
[0016] In the above implementation process, the transmittance formula of the nanopore structure can be determined based on the energy of the outgoing light, the energy of the incident light, the number of nanopore structures, and the scattering cross-section of the nanopore structure, so as to obtain the second structural parameter that can achieve the target transmittance within the target wavelength range, thereby achieving ultra-wideband high absolute efficiency.
[0017] In a second aspect, an embodiment of the present application further provides a method for preparing an ultra-wideband metasurface, the method comprising: Determine the corresponding target transparent medium based on the functional requirements of the metasurface; By laser processing technology, based on the structure determined by the ultra-wideband metasurface design method according to any one of the first aspects above, a metasurface having multiple unit structures is obtained by processing inside the target transparent medium.
[0018] In the above implementation process, the target transparent medium that can meet the functional requirements of the metasurface can be first determined according to the functional requirements of the metasurface, and then the target transparent medium can be processed inside by laser processing technology according to the geometric parameters of the metasurface structure determined in the ultra-wideband metasurface design method to induce the generation of a unit structure with a nanopore structure, thereby obtaining a metasurface with multiple unit structures to achieve the functional effect of high absolute efficiency of ultra-wideband.
[0019] In a third aspect, an embodiment of the present application further provides an ultra-wideband metasurface, the metasurface comprising: a target transparent medium; wherein the metasurface is prepared based on the ultra-wideband metasurface preparation method described in the second aspect above; A plurality of unit structures are arranged inside the target transparent medium.
[0020] In the above implementation process, the metasurface prepared based on the above-mentioned ultra-wideband metasurface preparation method includes a target transparent medium and a plurality of unit structures arranged inside the target transparent medium, so as to transmit light through the target transparent medium as a substrate, and realize ultra-wideband high absolute efficiency optical signal processing through the plurality of unit structures arranged therein. The unit structure is arranged inside the target transparent medium, which effectively improves the reliability and stability of the unit structure, thereby improving the stability of the metasurface during operation.
[0021] Optionally, in the light transmission direction, the centers of the plurality of unit structures are coaxially arranged.
[0022] In the above implementation process, the multiple unit structures arranged inside the target transparent medium are coaxially arranged in the direction of light transmission, so that the multiple unit structures can be projected and overlapped in the direction of light transmission, effectively improving the consistency and effectiveness of the relative positions of the multiple unit structures during light processing.
[0023] Optionally, in the light transmission direction, the angle of the unit structure close to the incident light is a reference angle, and the subsequent unit structures have a target rotation angle with respect to the reference angle.
[0024] In the above implementation process, in the direction of light transmission, the angle of the unit structure closest to the incident light can be used as the reference angle, and each subsequent unit structure has a corresponding target rotation angle with respect to the reference angle, so as to achieve ultra-wideband dispersion compensation through the target rotation angle and enable the metasurface to meet the target relative efficiency.
[0025] In summary, the embodiments of the present application provide an ultra-wideband metasurface design method, a preparation method, and an ultra-wideband metasurface, which can determine the first structural parameters through an inverse design method, and combine the second structural parameters to determine a unit structure that can be applied to the target wavelength range and can achieve the target relative efficiency and target transmittance. This effectively improves the bandwidth of the designed metasurface to achieve high absolute efficiency of the ultra-wideband, reduce the loss of light passing through the metasurface, and meet the current usage requirements of various optical application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.
[0027] Figure 1 A schematic diagram of a process for designing an ultra-wideband metasurface according to an embodiment of the present application; Figure 2 A detailed flowchart of step S100 provided in an embodiment of the present application; Figure 3 A detailed flowchart of step S200 provided in an embodiment of the present application; Figure 4 A schematic flow chart of a method for preparing an ultra-wideband metasurface provided in an embodiment of the present application; Figure 5 A schematic structural diagram of an ultra-wideband metasurface provided in an embodiment of the present application.
[0028] Icon: 410 - target transparent medium; 420 - unit structure; A - light transmission direction. DETAILED DESCRIPTION
[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of them. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the embodiments of the present application.
[0030] Currently, the relative bandwidth of metasurfaces (the ratio of bandwidth to central wavelength when efficiency exceeds 90%) is typically less than 50%, and most of the time, relative efficiencies (the ratio of the energy of modulated light in the outgoing light to the total energy of the outgoing light) are used. Due to factors such as resonant absorption and scattering losses in the unit structure, metasurfaces struggle to achieve high transmittance over ultra-wideband, meaning they struggle to achieve high absolute efficiency (the ratio of the energy of modulated light in the outgoing light to the total energy of the incident light, calculated by multiplying relative efficiency and transmittance). Consequently, light losses through metasurfaces are significant, making them unsuitable for current applications.
[0031] In order to solve the above problems, the embodiments of the present application provide an ultra-wideband metasurface design method, a preparation method and an ultra-wideband metasurface, which can determine the first structural parameters through an inverse design method, and combine the second structural parameters to determine a unit structure that can be applied to the target wavelength range and can achieve the target relative efficiency and target transmittance, effectively improving the bandwidth of the designed metasurface to achieve high absolute efficiency of the ultra-wideband, reduce the loss of light passing through the metasurface, and meet the current usage requirements of various optical application scenarios.
[0032] See also Figure 1 , Figure 1 A schematic flow chart of an ultra-wideband metasurface design method provided in an embodiment of the present application, the method may include steps S100-S200.
[0033] Step S100 : determining first structural parameters of a unit structure within a metasurface based on an inverse algorithm according to a target wavelength range and a target relative efficiency.
[0034] During the design process, the target wavelength range applicable to the metasurface and the target relative efficiency to be achieved are first determined, and the first structural parameters of the unit structure within the metasurface are determined using an inverse algorithm.
[0035] Step S200 : determining a second structural parameter of the unit structure according to the target wavelength range and the target transmittance.
[0036] Among them, the second structural parameter of the unit structure can be determined according to the target wavelength range and the target transmittance that the metasurface needs to achieve. The structure of the metasurface includes multiple unit structures determined based on the first structural parameter and the second structural parameter. The actual structure of the unit structure can be determined by the first structural parameter and the second structural parameter to determine the ultra-wideband metasurface including the unit structure.
[0037] Optionally, the target wavelength range, target relative efficiency, and target transmittance can be determined based on an analysis of the functional requirements of the metasurface. Alternatively, the target wavelength range, target relative efficiency, and target transmittance can be determined by querying a database based on the functional requirements or model. Parameter data corresponding to multiple models or functional requirements can be stored in the database in advance, and during design, the required parameters can be directly queried based on the requirements or model. For example, the target wavelength range can be 400nm to 1700nm, the target relative efficiency can be set to greater than or equal to 98%, and the target transmittance can be set to greater than or equal to 95%.
[0038] It should be noted that the first structural parameter may include: a target number of unit structure stacking layers, a target rotation angle generated by each unit structure relative to a reference angle, and a target phase delay for each unit structure. Since a metasurface may include multiple unit structures stacked along the light transmission direction, the target number of stacking layers may be the number of unit structures in the metasurface. To achieve ultra-wideband dispersion compensation, ensuring that each wavelength within the ultra-wideband has the same target phase delay to achieve a high target relative efficiency, the multiple unit structures may generate corresponding target rotation angles relative to the reference angle to achieve a high target relative efficiency. Since the unit structures include laser-induced nanopore structures, such as nanopore arrays, the second structural parameter may include: a target number and target diameter of the nanopore structures within the unit structures. These structural parameters, such as the target number and target diameter of the nanopore structures, can be used to achieve a corresponding target transmittance. Design can be based on multiple perspectives, including the stacking, relative position, functionality, and specific structure of the multiple unit structures, effectively improving the functional reliability of the resulting unit structures.
[0039] Optionally, various types of parameters in the first structural parameter and the second structural parameter may be designed according to an actual target wavelength range, a target relative efficiency, and a target transmittance.
[0040] Optionally, the influence factor of each unit structure on the incident light may be determined based on the rotation angle, phase delay, thickness, and equivalent refractive index for different polarized lights of the unit structure.
[0041] It should be noted that, during the design process, the influence factor of the unit structure on the incident light can be equivalent to a corresponding two-dimensional matrix. The influence factor of each unit structure on the incident light can be: ; in, Indicates the rotation angle, Indicates wavelength The phase delay when and are the equivalent refractive indices of the unit structure for o light (ordinary light) and e light (extraordinary light), is the thickness of the unit structure. The various structural parameters of the unit structure can be designed in combination with the influencing factors, so that the unit structure can achieve the target relative efficiency and target transmittance in the application scenario of the target wavelength range, and the designed metasurface can achieve high absolute efficiency in the ultra-wideband.
[0042] exist Figure 1 In the illustrated embodiment, a first structural parameter can be determined through an inverse design method, and combined with a second structural parameter to determine a unit structure that can be applied to a target wavelength range and can achieve a target relative efficiency and a target transmittance. This effectively increases the bandwidth of the designed metasurface to achieve high transmittance over an ultra-wideband, that is, high absolute efficiency over an ultra-wideband, reduces light loss through the metasurface, and meets the current usage requirements of various optical application scenarios.
[0043] Optionally, see Figure 2 , Figure 2 A detailed flowchart of step S100 is provided in an embodiment of the present application. Step S100 may include steps S110-S120.
[0044] Step S110 : determining a target wavelength range and a target relative efficiency according to functional requirements of the metasurface.
[0045] Among them, considering the different functional characteristics of metasurfaces in different application scenarios, we can analyze the functional requirements of the metasurfaces to determine the target wavelength range applicable to the metasurfaces and the target relative efficiency that the metasurfaces need to achieve. We can also determine the target wavelength range and target relative efficiency directly from the database based on the functional requirements.
[0046] Step S120 , based on an inverse algorithm, calculation is performed according to the target wavelength range and the target relative efficiency to determine a first structural parameter that meets the target relative efficiency within the target wavelength range.
[0047] Among them, various types of inverse algorithms can be used to calculate according to the target wavelength range and the target relative efficiency to determine the first structural parameters that can meet the target relative efficiency within the target wavelength range.
[0048] For example, the inverse algorithm may include a particle swarm optimization algorithm, a simulated annealing method, a genetic algorithm, a deep learning algorithm, and other algorithms that can perform inverse design on the first structural parameters according to the results of the relative efficiency of the simulation.
[0049] Optionally, the target stacking number of unit structures is N, and the incident light E in After passing through the N-layer structure, the emitted light It can be expressed as:
[0050] Therefore, the number of stacked layers of the unit structure, the rotation angle of each unit structure (i.e. ) and the phase delay of each unit structure (i.e. ) as the optimization variable, with the target wavelength range With the goal of meeting the target relative efficiency, an inverse algorithm design method is adopted to obtain the corresponding multi-layer unit structure that can achieve high relative efficiency in the ultra-wideband range.
[0051] For example, when the metasurface is an ultra-wideband polarization conversion device, the target phase delay of each metasurface layer can be The target number of stacked layers of the unit structure is set to 35 to achieve an ultra-wideband quarter-wave plate with a relative efficiency of >98.5% (target relative efficiency) in the target wavelength range of 400nm~1100nm. Alternatively, the target phase delay of each metasurface can be The target number of stacked layers of the unit structure is set to 60nm, and 30 layers are required to achieve an ultra-wideband half-wave plate with a relative efficiency of >98.5% (target relative efficiency) in the target wavelength range of 450nm~1700nm.
[0052] For example, when the metasurface is an ultra-wideband high-efficiency vortex beam and vector beam generator, the target phase delay of each layer of the metasurface can be The target cell structure thickness is set at 18nm, with a target stacking number of 70 layers. This is to achieve an ultra-wideband half-wave plate with a relative efficiency >99% (target relative efficiency) within the target wavelength range of 400nm to 1100nm. Based on the designed cell structure, by rotating the fast axis of a vortex light generator with a topological charge of 1 according to its phase distribution, an ultra-wideband, high-efficiency vortex light generator is obtained. Vortex light is generated with left-handed and right-handed circularly polarized incident light, and radially polarized light is generated with x-polarized incident light.
[0053] exist Figure 2 In the illustrated embodiment, the validity of the first structural parameter is effectively improved to improve the functional reliability of the unit structure.
[0054] Optionally, see Figure 3 , Figure 3 A detailed flow chart of step S200 is provided in an embodiment of the present application. Step S200 may include steps S210-S220.
[0055] Step S210 : Determine a target wavelength range and a target transmittance according to the functional requirements of the metasurface.
[0056] Among them, we can first analyze the functional requirements corresponding to the metasurface to determine the target wavelength range applicable to the metasurface and the target transmittance that the metasurface needs to achieve. We can also directly determine the target wavelength range and target transmittance based on the functional requirements from the database.
[0057] Optionally, the functional requirements can be determined based on the model and type of the metasurface, the polarization state of the incident light and the polarization state of the outgoing light set during optimization, etc.
[0058] Step S220 , determining a second structural parameter according to the target transmittance and the transmittance formula of the nanopore structure in the unit structure in combination with the target wavelength range.
[0059] Among them, based on the target transmittance and in combination with the transmittance formula of the nanopore structure in the unit structure, the second structural parameter that can achieve the target transmittance within the target wavelength range can be determined.
[0060] Alternatively, the transmittance formula may be determined based on the energy of the outgoing light, the energy of the incident light, the number of nanopore structures, and the scattering cross section of the nanopore structures.
[0061] It should be noted that the transmittance formula of the nanopore structure in the unit structure can include: ; in, is the energy of the emitted light, is the energy of the incident light, is the number of nanopore structures per unit volume, wavelength The scattering cross section of the nanopore structure.
[0062] Among them, taking the target wavelength range of visible near infrared as an example, the loss of the nanopore structure in the visible near infrared band is mainly caused by Rayleigh scattering, and its scattering cross section is The formulas for determining include: ; in, wavelength When , the refractive index of the transparent medium where the metasurface is located is, is the diameter of the nanopore structure. According to the transmittance formula, the number and diameter of the nanopore structure in the unit structure can be used as optimization variables to optimize the target wavelength range. The target transmittance is met as the goal, the appropriate number of targets and target diameter are determined, and the structural characteristics of high absolute efficiency of ultra-wideband are achieved.
[0063] exist Figure 3 In the illustrated embodiment, the validity of the second structural parameter is effectively improved to improve the functional reliability of the unit structure.
[0064] See also Figure 4 , Figure 4 A schematic flow chart of a method for preparing an ultra-wideband metasurface provided in an embodiment of the present application, the method may include steps S310-S320.
[0065] Step S310: Determine the corresponding target transparent medium according to the functional requirements of the metasurface.
[0066] Among them, considering that different materials have different characteristics based on different bands, we can first determine the target transparent medium that can meet the functional requirements of the metasurface based on the functional requirements. For example, if the applicable target wavelength range determined according to the functional requirements is the visible and near-infrared bands, quartz glass can be selected as the target transparent medium within this band.
[0067] Optionally, to reduce the adverse effects of impurities on processing and preparation, the target transparent medium can be pretreated. Pretreatment can include cleaning, drying, and other processes. For example, a quartz glass sample can be cleaned by ultrasonic cleaning in anhydrous ethanol, deionized water, and acetone for 15 minutes each. After cleaning, it can be dried with nitrogen. The quartz glass can then be placed on the 3D high-precision translation stage of the femtosecond processing system and secured for processing.
[0068] It should be noted that the design and preparation methods of metasurfaces are not limited to the visible and near-infrared bands. The corresponding transparent medium can be selected according to the requirements of different bands such as ultraviolet, medium-wave infrared, and long-wave infrared, and the corresponding unit structure can be designed in the transparent medium for processing.
[0069] In step S320 , a metasurface having multiple unit structures is obtained by processing the target transparent medium based on the determined structure using laser processing technology.
[0070] Among them, laser processing technology can be used to process the inside of the target transparent medium according to the geometric parameters of the metasurface structure determined in the ultra-wideband metasurface design method, so as to induce the generation of a unit structure with a nanopore structure, thereby obtaining a metasurface with multiple unit structures to achieve the functional effect of high absolute efficiency of ultra-wideband.
[0071] For example, a grayscale image of the designed metasurface structure can be imported into the control software of a femtosecond laser processing system. Using a "bottom-up, layer-by-layer scanning" approach, the nanostructured structure with spatially distributed orientation can be fabricated by real-time control of the laser polarization direction during high-speed processing. The femtosecond laser is focused into the interior of the quartz glass to induce the formation of nanopore structures, such as birefringent elliptical nanopore arrays, to create multi-layer cascade structures.
[0072] exist Figure 4 In the described embodiments, the prepared metasurface can achieve ultra-wideband high absolute efficiency and meet the application requirements of various different application scenarios.
[0073] See also Figure 5 , Figure 5 This is a schematic diagram of the structure of an ultra-wideband metasurface provided in an embodiment of the present application, wherein the ultra-wideband metasurface is prepared based on the ultra-wideband metasurface preparation method described above. The ultra-wideband metasurface may include: a target transparent medium 410; wherein the metasurface is prepared based on the ultra-wideband metasurface preparation method.
[0074] Optionally, the target transparent medium 410 may include various types of materials having transparent properties within corresponding applicable wavelength bands, such as quartz glass or silicon wafer.
[0075] It should be noted that multiple unit structures 420 are disposed within the target transparent medium 410. Light is transmitted through the target transparent medium 410 as a substrate, and ultra-wideband, high-absolute-efficiency optical signal processing is achieved through the multiple unit structures 420 disposed therein. The unit structures 420 disposed within the target transparent medium 410 effectively improve the reliability and stability of the unit structures 420, thereby enhancing the stability of the metasurface during operation.
[0076] Optionally, in the light transmission direction A, i.e., the optical path or optical path, the centers of multiple unit structures 420 are coaxially arranged so that the multiple unit structures 420 can be projected and overlapped in the light transmission direction A. Through the aligned multi-layer structure, the consistency and effectiveness of the relative positions of the multiple unit structures 420 during light processing are effectively improved.
[0077] Optionally, in the light transmission direction A, the angle of the unit structure 420 close to the incident light can be used as a reference angle, and subsequent unit structures 420 have a target rotation angle between the reference angle to achieve ultra-wideband dispersion compensation through the target rotation angle and enable the metasurface to meet the target relative efficiency.
[0078] For example, the angle of the unit structure 420 at other positions may also be used as the reference angle, as long as the relative rotation between the reference angle and the target rotation angle can be reflected.
[0079] It should be noted that the prepared metasurface can realize various types of complex light field control functions, such as vortex light field generation, vector light field generation, holography, metalens, etc., and can be used in various optical fields such as ultrafast laser processing, broadband imaging, and optical communications.
[0080] Optionally, a chiral agent may be added to the nematic liquid crystal to cause the liquid crystal molecules to form a twisted structure when the liquid crystal is spin-coated to compensate for dispersion. The direction and magnitude of the twist angle of the twisted structure can be controlled by the type and concentration of the chiral agent.
[0081] The foregoing is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.
[0082] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.
[0083] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.
Claims
1. A method for designing an ultra-wideband metasurface, characterized in that: The method comprises: According to the target wavelength range and the target relative efficiency, the first structural parameters of the unit structure in the metasurface are determined based on an inverse algorithm; determining a second structural parameter of the unit structure according to the target wavelength range and the target transmittance; The structure of the metasurface includes a plurality of unit structures determined based on the first structural parameters and the second structural parameters.
2. The method according to claim 1, characterized in that in, The first structural parameters include: a target number of stacked layers of the unit structure, a target rotation angle generated by each unit structure based on a reference angle, and a target phase delay amount of each unit structure; The second structural parameters include: a target number and a target diameter of nanopore structures in the unit structure.
3. The method according to claim 2, characterized in that in, The influence factor of each unit structure on the incident light is determined based on the rotation angle, phase delay, thickness and equivalent refractive index of the unit structure for different polarized lights.
4. The method according to claim 1, wherein The step of determining the first structural parameters of the unit structure within the metasurface based on an inverse algorithm according to the target wavelength range and the target relative efficiency includes: Determining the target wavelength range and the target relative efficiency according to functional requirements corresponding to the metasurface; Based on the inverse algorithm, calculation is performed according to the target wavelength range and the target relative efficiency to determine the first structural parameters that meet the target relative efficiency within the target wavelength range; The inverse algorithm includes at least one of a particle swarm algorithm, a simulated annealing method, a genetic algorithm, and deep learning.
5. The method according to claim 1, characterized in that Determining the second structural parameter of the unit structure according to the target wavelength range and the target transmittance includes: Determining the target wavelength range and the target transmittance according to functional requirements corresponding to the metasurface; The second structural parameter is determined according to the target transmittance and a transmittance formula of the nanopore structure in the unit structure in combination with the target wavelength range.
6. The method according to claim 5, characterized in that in, The transmittance formula is determined based on the energy of the outgoing light, the energy of the incident light, the number of the nanopore structures, and the scattering cross section of the nanopore structures.
7. A method for preparing an ultra-wideband metasurface, characterized in that: The method comprises: Determine the corresponding target transparent medium based on the functional requirements of the metasurface; By laser processing technology, based on the structure determined by the ultra-wideband metasurface design method according to any one of claims 1 to 6, a metasurface having multiple unit structures is obtained by processing inside the target transparent medium.
8. An ultra-wideband metasurface, characterized in that: The metasurface comprises: a target transparent medium; wherein the metasurface is prepared based on the ultra-wideband metasurface preparation method according to claim 7; A plurality of unit structures are arranged inside the target transparent medium.
9. The metasurface according to claim 8, wherein: In the light transmission direction, the centers of the plurality of unit structures are coaxially arranged.
10. The metasurface according to claim 8, wherein: In the light transmission direction, the angle of the unit structure close to the incident light is a reference angle, and the subsequent unit structures have a target rotation angle with respect to the reference angle.