Asymmetric transmission optical device, test method and electronic device

Abstract

The invention relates to an asymmetric transmission optical device, a test method and an electronic device, and belongs to the technical field of nano optics and photonics. Comprising a dielectric nano-particle array which comprises a plurality of dielectric nano-particles, and the dielectric nano-particles are periodically arranged according to a preset interval; wherein the height of the dielectric nano particles is 60 nm to 150 nm; and the dielectric substrate is arranged below the dielectric nanoparticle array. The test method comprises the following steps: establishing a periodic array model according to the optical device, and setting structural parameters of the model to obtain an optimal periodic array model; performing asymmetric transmission mechanism analysis and structural parameter analysis by using the optimal periodic array model; and according to an analysis result, obtaining an optimal structure parameter of asymmetric transmission. The problems of high loss, narrow bandwidth and polarization sensitivity are avoided, and the defects of high preparation difficulty, high cost and poor compatibility caused by a complex geometric structure or a specific material are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-optics and photonics, and in particular to an asymmetric transmission optical device, a testing method and an electronic device. Background Art

[0002] Asymmetric light transmission is a unique optical property that enables directional selectivity in light propagation. The underlying principle is that the designed device responds differently to stimuli from different directions, allowing electromagnetic waves to propagate in one direction while blocking those from the opposite direction. This property holds great promise for applications in a wide range of fields, including electromagnetic shielding, isolators, and solar cells. It can be used to create isolation between components in optical and communication systems and to decouple light from different paths in quantum optics applications. Furthermore, it can improve the efficiency of solar cell systems by trapping light and enhancing its absorption.

[0003] Conventional methods for controlling electromagnetic waves rely primarily on the curved surface structure of the medium, customizing the desired output wavefront by accumulating phase delays during wave propagation. However, a significant drawback of this approach is that the structural dimensions are typically much larger than the operating wavelength, which limits its application in compact systems, especially when integrated with other devices or miniaturized systems.

[0004] With the rapid development of nanofabrication technology and the continuous deepening of research in related disciplines, the preparation methods and theoretical research of nanostructures have made significant progress, becoming mature and feasible. However, while these implementation schemes have achieved success in some applications, many problems still exist. For example, the physical mechanisms behind asymmetric light transmission in nanostructures and their related properties lack in-depth and comprehensive research, and nanostructures that achieve asymmetric light transmission have poor compatibility with equipment or devices, and their performance is limited.

[0005] In the practical application of asymmetric optical transmission devices, conventional technologies often use metal nanoparticles as core components. However, metal nanoparticles suffer from inherent high loss, narrow effective bandwidth, and polarization sensitivity, which severely limit the overall performance and application range of the devices. Furthermore, existing technologies often rely on complex geometric structures or have strict requirements on the selection of structural parameters to achieve asymmetric optical transmission, which not only increases the difficulty and cost of device preparation, but also further limits their widespread application in practical scenarios. Summary of the Invention

[0006] To this end, the technical problem to be solved by the present invention is to overcome the high loss, narrow bandwidth and polarization sensitivity problems of metal nanoparticles used in the existing technology, as well as the defects of difficulty in preparation, high cost and poor compatibility brought about by traditional methods relying on complex geometric structures or specific materials.

[0007] In a first aspect, to solve the above technical problems, the present invention provides an asymmetric transmission optical device, comprising: A dielectric nanoparticle array comprising a plurality of dielectric nanoparticles, each of the dielectric nanoparticles being periodically arranged at a preset spacing; wherein the height of the dielectric nanoparticles is 60 nm to 150 nm; The dielectric substrate is used to support the dielectric nanoparticle array and is arranged below the dielectric nanoparticle array.

[0008] In one embodiment of the present invention, the dielectric nanoparticles are in the shape of axisymmetric cylinders.

[0009] In one embodiment of the present invention, the material of the dielectric nanoparticles is at least one of silicon, titanium dioxide, silicon nitride, and gallium arsenide.

[0010] In one embodiment of the present invention, the refractive index of the dielectric substrate is 1.5-10.

[0011] In one embodiment of the present invention, the preset distances between adjacent dielectric nanoparticles are the same.

[0012] In one embodiment of the present invention, the preset spacing is 120 nm to 800 nm.

[0013] In a second aspect, to solve the above technical problems, the present invention provides a method for testing an optical device with asymmetric transmission, comprising: S1. Establishing a periodic array model based on the above-mentioned asymmetric transmission optical device, setting structural parameters of the periodic array model, and obtaining an optimal periodic array model; S2. Setting forward illumination and backward illumination on the optimal periodic array model respectively; performing asymmetric transmission mechanism analysis under the forward illumination and backward illumination to obtain the relationship between different orders of diffraction and transmittance of the optical device; S3. Analyzing the relationship between the structural parameters and the asymmetric transmission phenomenon based on the relationship between the different diffraction orders and the transmittance; S4. Obtaining optimal structural parameters for asymmetric transmission based on the relationship between the different diffraction orders and transmittance and the relationship between the structural parameters and the asymmetric transmission phenomenon.

[0014] In one embodiment of the present invention, in S2, forward illumination and backward illumination are respectively set on the optimal periodic array model; and the steps of performing asymmetric transmission mechanism analysis under the forward illumination and backward illumination are as follows: According to the periodic array model, simulation analysis is performed on the transmittance of the optical device under forward and backward illumination conditions; By adjusting different wavelengths, analyzing the diffraction orders and the transmission energy of the corresponding diffraction orders, the relationship between the different diffraction orders and the transmittance is obtained; wherein, the process of analyzing the diffraction orders and the transmission energy of the corresponding diffraction orders includes introducing a cutoff wavelength formula to explain the diffraction suppression phenomenon.

[0015] In one embodiment of the present invention, S3, the relationship between the structural parameters and the asymmetric transmission phenomenon includes: when the refractive index of the dielectric substrate of the optical device is greater than 3, the asymmetric transmission phenomenon of the optical device tends to be stable; when the refractive index of the dielectric substrate is greater than 4, the wavelength position when the optical device obtains maximum asymmetric transmission remains unchanged.

[0016] In a third aspect, in order to solve the above technical problems, the present invention provides an electronic device, comprising the above-mentioned asymmetric transmission optical device.

[0017] The above technical solution of the present invention has the following beneficial effects compared with the prior art: (1) The present invention discloses an asymmetric optical device, testing method, and electronic device that achieves high-performance asymmetric light transmission by optimizing the dielectric nanoparticle array structure. Compared to traditional metal nanoparticles, dielectric nanoparticle arrays have lower intrinsic loss and a wider operating bandwidth, enabling efficient operation over a wider wavelength range while reducing optical signal attenuation, thereby improving the overall performance of the optical device.

[0018] (2) The structural design of the present invention makes the optical device insensitive to the polarization state of the incident light. This feature improves the flexibility of the device in practical applications, enabling it to adapt to a variety of different optical systems without the need for additional polarization control devices. At the same time, the structure is simple and easy to integrate with existing optical systems and miniaturized equipment. Its preparation process is compatible with existing semiconductor manufacturing technology, enabling large-scale production and application.

[0019] (3) This invention optimizes the relevant structural parameters by constructing a periodic array model and conducting in-depth analysis of the asymmetric transmission mechanism. This process not only improves the performance of asymmetric light transmission but also provides important reference value for the theoretical research and practical application of this technology in photovoltaic devices, display equipment, optical isolation and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 Schematic diagram of the structure of an asymmetric transmission optical device in a preferred embodiment of the present invention; Figure 2This is a flow chart of a method for testing an asymmetric transmission optical device in a preferred embodiment of the present invention; Figure 3 (a) is a comparison of the transmittance of a periodic silicon cylinder array on a dielectric substrate under forward and backward illumination in a preferred embodiment of the present invention; Figure 3 (b) is a comparison chart of the reflectivity of a periodic silicon cylinder array on a dielectric substrate under forward and backward illumination in a preferred embodiment of the present invention; Figure 3 (c) is a comparison chart of the absorptivity of a periodic silicon cylinder array on a dielectric substrate under forward and backward illumination in a preferred embodiment of the present invention; Figure 4 (a) is a graph showing the transmittance of a periodic silicon cylindrical array on a dielectric substrate as a function of the polarization angle of the incident light when the polarization angle of the incident light is 0°-90° under forward illumination in a preferred embodiment of the present invention; Figure 4 (b) is a graph showing the transmittance of a periodic silicon cylindrical array on a dielectric substrate as a function of the polarization angle of the incident light when the polarization angle of the incident light is 0 ° -90 ° under backward illumination in a preferred embodiment of the present invention; Figure 5 (a) is a graph showing the diffraction order supported by the transmittance under forward and backward illumination in a preferred embodiment of the present invention; Figure 5 (b) is a diagram showing the transmittance variation caused by diffraction under forward illumination in a preferred embodiment of the present invention; Figure 5 (c) is a diagram showing the transmittance variation caused by diffraction under backward illumination in a preferred embodiment of the present invention; Figure 6 (a) is a graph showing the transmittance variation of a periodic silicon cylinder array on a dielectric substrate with a refractive index ranging from 1 to 10 under forward illumination in a preferred embodiment of the present invention; Figure 6 (b) is a graph showing the transmittance variation of a periodic silicon cylinder array on a dielectric substrate with a refractive index ranging from 1 to 10 under backward illumination in a preferred embodiment of the present invention; Figure 6 (c) is a preferred embodiment of the present invention. Figure 6 (a) and Figure 6 (b) Schematic diagram of the asymmetric difference calculated from the transmittance; Figure 6 (d) is a preferred embodiment of the present invention Figure 6 (c) Schematic diagram of the asymmetric difference corresponding to the dotted box; Figure 7 (a) is a graph showing the transmittance variation of a periodic silicon cylinder array on a dielectric substrate under forward illumination as the cylinder height changes in a preferred embodiment of the present invention; Figure 7(b) is a graph showing the transmittance variation of a periodic silicon cylinder array on a dielectric substrate under backward illumination as the cylinder height varies in a preferred embodiment of the present invention; Figure 7 (c) is a preferred embodiment of the present invention. Figure 7 (a) and Figure 7 (b) Schematic diagram of the asymmetric difference calculated from the transmittance; Figure 7 (d) is a preferred embodiment of the present invention Figure 7 (c) Schematic diagram of the asymmetric difference corresponding to the dotted box; Figure 8 (a) is a schematic diagram of the structure of a photodiode placed on a gold film in a preferred embodiment of the present invention; Figure 8 (b) is a cross-sectional view of a photodiode placed on a gold film in a preferred embodiment of the present invention; Figure 9 (a) is a graph showing the reflectivity of the gold film, the gold film and the dielectric substrate, and the gold film and the photodiode when the refractive index of the dielectric substrate is 5.5 in a preferred embodiment of the present invention; Figure 9 (b) is a graph showing the reflectivity of the gold film, the gold film and the dielectric substrate, and the gold film and the photodiode when the refractive index of the dielectric substrate is 5 in a preferred embodiment of the present invention; Figure 9 (c) is a graph showing the reflectivity of the gold film, the gold film and the dielectric substrate, and the gold film and the photodiode when the refractive index of the dielectric substrate is 6 in a preferred embodiment of the present invention; Figure 9 (d) is a reflectivity curve diagram of the gold film, the gold film and the dielectric substrate, and the gold film and the photodiode when the refractive index of the dielectric substrate is 6.5 in a preferred embodiment of the present invention.

[0021] Explanation of the accompanying figures in the specification: 1. dielectric substrate; 2. dielectric nanoparticles; 3. gold film. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention. Example 1

[0023] Reference Figure 1 As shown, an embodiment of the present invention provides an asymmetric transmission optical device, including: A dielectric nanoparticle array comprising a plurality of dielectric nanoparticles 2, each of which is periodically arranged at a preset pitch; wherein the height of each dielectric nanoparticle is 60 nm to 150 nm; The dielectric substrate 1 is used to support the dielectric nanoparticle array and is disposed below the dielectric nanoparticle array.

[0024] Embodiments of the present invention provide an optical device with asymmetric transmission. By optimizing the structure of a dielectric nanoparticle array, high-performance asymmetric light transmission is achieved. Compared with traditional metal nanoparticles, dielectric nanoparticle arrays have lower intrinsic loss and a wider operating bandwidth, enabling efficient operation across a wider wavelength range while reducing optical signal attenuation, thereby improving the overall performance of the optical device.

[0025] Specifically, although metal particles are often considered for use in array structures due to their excellent optical properties, their main drawback is their inherent high loss, which can seriously affect the performance of asymmetric light transmission. High-refractive-index dielectric nanoparticles 2 can serve as an alternative to metal nanoparticles. Specifically, dielectric nanoparticles 2 have metal-like optical properties, low absorption loss, and the interference of electric and magnetic resonances within dielectric nanoparticles 2 can also affect the scattering of the particles, particularly the directional radiation effect, which can be utilized to achieve asymmetric light transmission.

[0026] Specifically, the material of the dielectric nanoparticles can be selected from one or more high-refractive-index materials such as silicon, titanium dioxide, silicon carbide, and gallium arsenide. Given the wide range of practical applications and high refractive index characteristics of silicon, embodiments of the present invention preferably use silicon as the primary material for the dielectric nanoparticles to achieve better optical performance and a higher cost-effectiveness.

[0027] Specifically, the dielectric nanoparticles 2 are shaped like axisymmetric cylinders and can be designed into various geometric forms, such as hemispherical, spherical, or cubic shapes. However, comparative analysis revealed that cylindrical nanoparticles have a stronger scattering effect than hemispherical, spherical, and cubic shapes, thereby exhibiting significant advantages in asymmetric light transmission performance, particularly in enhancing the directional transmission capability of light. Therefore, in the embodiments of the present invention, cylindrical is the preferred shape for the dielectric nanoparticles 2 to achieve better optical performance.

[0028] Furthermore, the dielectric nanoparticles 2 have a height range of 60nm to 150nm and a radius range of 60nm to 150nm. This size range significantly enhances the dielectric nanoparticles' ability to scatter light and modulate its refractive index, effectively altering the propagation properties of light and enabling the design of optical sensors and metamaterials. Furthermore, their size, which is close to the wavelength of light, enhances light-matter interactions.

[0029] Specifically, dielectric nanoparticles 2 are arranged on a dielectric substrate 1 in a periodic manner. The preset spacing in the x and y directions is set to P, so that the structure is independent of the polarization state of the incident light. nsub On the dielectric substrate 1, the existence of the dielectric substrate 1 not only changes the scattering distribution of the cylinder and the symmetry of the periodic array diffraction, but also further enhances the scattering of the cylinder due to the increase in the local light state density in the dielectric substrate 1.

[0030] Furthermore, the preset spacing P between adjacent dielectric nanoparticles 2 ranges from 120 nm to 800 nm. n sub The range is controlled between 1.5 and 10.

[0031] By optimizing the height, radius, spacing of the nanoparticles and the refractive index of the dielectric substrate 1, the optical performance is improved, the light capture capability and the uniformity of the scattering distribution are enhanced, and the preparation difficulty and cost are reduced.

[0032] The embodiment of the present invention achieves high-performance asymmetric light transmission by optimizing the dielectric nanoparticle array structure. By adopting the dielectric nanoparticle array structure, compared with traditional metal nanoparticles, it has lower inherent loss and wider operating bandwidth, can work efficiently in a wider wavelength range, and at the same time reduces the attenuation of the optical signal, thereby improving the overall performance of the system. In addition, the structural design of the embodiment of the present invention makes the optical device insensitive to the polarization state of the incident light. This feature greatly improves the flexibility of the device in practical applications and can adapt to a variety of different optical systems without the need for additional polarization control devices. At the same time, the structure is simple and easy to integrate with existing optical systems and miniaturized equipment. Its preparation process is compatible with existing semiconductor manufacturing technology, and can achieve large-scale production and application, reducing costs and improving market competitiveness. Example 2

[0033] Reference Figure 2 As shown, this embodiment provides a method for testing an asymmetric transmission optical device, including but not limited to the following steps: S1. Establish a periodic array model according to the asymmetric transmission optical device described in Example 1, set structural parameters of the periodic array model, and obtain an optimal periodic array model; S2. Set forward illumination and backward illumination on the optimal periodic array model respectively; perform asymmetric transmission mechanism analysis under forward illumination and backward illumination to obtain the relationship between different diffraction orders and transmittance of the optical device; S3. Analyze the relationship between structural parameters and asymmetric transmission phenomena based on the relationship between different diffraction orders and transmittance; S4. Based on the relationship between different diffraction orders and transmittance and the relationship between structural parameters and asymmetric transmission phenomena, the optimal structural parameters for asymmetric transmission are obtained.

[0034] The embodiment of the present invention provides a method for testing optical devices with asymmetric transmission, which realizes the optimization of asymmetric transmission optical devices. First, based on the asymmetric transmission optical device described in Example 1, a periodic array model is constructed, and the structural parameters of the model are set to obtain an optimal periodic array model. Then, the forward and backward lighting conditions are set, and an in-depth asymmetric transmission mechanism analysis is performed on the optimal periodic array model to clarify the relationship between different diffraction orders and transmittance. On this basis, the influence of structural parameters on the asymmetric transmission phenomenon is further explored, and a quantitative relationship between the two is established. Finally, the relationship between the diffraction order and transmittance and the influence of structural parameters on asymmetric transmission are comprehensively considered to determine the optimal structural parameters for realizing asymmetric transmission. This design method not only improves the performance of optical devices, but also provides clear theoretical guidance for subsequent experimental preparation, and has important scientific significance and application value.

[0035] The prior art usually requires strict control of the structural parameters of the dielectric nanoparticles 2 to achieve high-efficiency asymmetric light transmission, and metal materials are usually selected. Although studies have achieved high-efficiency asymmetric light transmission, its effective bandwidth is very narrow. In addition, the prior art even proposed an asymmetric light transmission performance of up to 100%, but there are specific requirements for the pyramid structure and high refractive index substrate required to achieve this performance, which will be limited by the choice of materials or the complexity of the structure in practical applications. This embodiment studies high-efficiency asymmetric light transmission within a wide band through a periodic silicon cylindrical nanoparticle array on a dielectric substrate 1. At the same time, the nano-periodic array has low energy loss and anti-reflection light capture characteristics, and is independent of the polarization state of the incident light.

[0036] Specifically, in step S1, according to the optical device structure provided in embodiment 1, a periodic array model is established, such as Figure 1 shown. Figure 1 This diagram can be viewed as a schematic structural model of a periodic array of silicon cylindrical nanoparticles on a dielectric substrate 1. The symbols d and h represent the diameter and height of the silicon cylinders, respectively, and the symbol P represents the period of the array. The dielectric nanoparticle array structure comprises multiple dielectric nanoparticles 2, each of which is cylindrical in shape. To accurately simulate and optimize the model, structural parameters are set, including but not limited to key parameters such as the spacing between particles (i.e., the period of the dielectric nanoparticle array). Using advanced simulation techniques, these parameters are systematically adjusted and optimized to ensure theoretically optimal model performance. This process involves testing different parameter combinations and analyzing the results to identify the parameter configuration that produces the strongest scattering effect and the best asymmetric light transmission performance.

[0037] Specifically, step S2 analyzes the asymmetric light transmission mechanism of the dielectric nanoparticle array in the optimal periodic array model, and obtains the specific content of the relationship between different diffraction orders and transmittance as follows: S210, based on the periodic array model, simulate and analyze the optical device under forward illumination (T f ) and backlighting (T b ) conditions.

[0038] Specifically, when the refractive index of the dielectric substrate 1 is n sub =5.5, silicon cylinder height h=125nm, silicon cylinder diameter d=160 nm, P=200nm, the transmittance of the periodically arranged silicon cylinder nanoparticle array on the dielectric substrate 1 under forward and backward illumination conditions is as follows: Figure 3 As shown in (a). It can be observed from the figure that, across the entire wavelength range from 300nm to 1100nm, the transmittance under forward illumination is higher than that under backward illumination, demonstrating a clear asymmetric light transmission phenomenon. In particular, at a wavelength of 540nm, the asymmetric difference in transmittance reaches a maximum value of 0.894, while the transmittance under backward illumination is almost zero. Furthermore, within the wavelength range of 460nm to 660nm, the asymmetric difference in transmittance is greater than 0.5, indicating strong asymmetry. Figure 3 (b) and Figure 3 (c) shows the reflectivity and absorptivity of the periodic silicon cylinder array on the dielectric substrate 1 under forward and backward illumination conditions, respectively. Figure 3 The absorption rate in (c) comes only from the silicon cylinder itself.

[0039] For the case of forward illumination, the reflectivity and absorptivity in the short-wave band are both high. At a wavelength of 540nm, the reflectivity is close to zero, while the absorptivity is 0.099. As the wavelength increases, the reflectivity remains at a low level, while the absorptivity continues to decrease and eventually approaches zero. For the case of backward illumination, the reflectivity and absorptivity are both high. At a wavelength of 540nm, the reflectivity is 0.644 and the absorptivity is 0.359. Under the same structural parameters, Figure 4 (a) and Figure 4 (b) Color plot showing the transmittance of a periodic array of silicon cylindrical nanoparticles on dielectric substrate 1 as a function of the polarization angle of the incident light under forward and backward illumination conditions. The diameter and height of the silicon cylinders are 160 nm and 125 nm, respectively, the dielectric substrate has a refractive index of 5.5, and the array period is 200 nm. Figure 4 (a) and Figure 4The color bar on the right side of (b) represents different transmittances, ranging from 0 to 1. Due to the geometric symmetry of the cylindrical structure and square period, the polarization angle range is set to 0° to 90°. Figure 4 It can be seen that at any polarization angle, the transmittance under forward or backward illumination remains stable within the entire wavelength range and does not change with the change of polarization angle.

[0040] Reference Figure 3 and Figure 4 The results in the figure show that the nanoperiodic array not only achieves asymmetric light transmission that is independent of the polarization state of the incident light, but also achieves high transmittance, low absorption, and low reflectance under forward illumination, while exhibiting low transmittance under backward illumination. These optical properties give it significant advantages in light capture, for example, it can be used to improve the performance of optoelectronic devices such as solar cells.

[0041] S220. Analyze the physical mechanism of asymmetric light transmission of the dielectric nanoparticle array on the dielectric substrate 1. This process includes adjusting different wavelengths, analyzing the diffraction orders and the transmission energy of the corresponding diffraction orders, and obtaining the relationship between different orders of diffraction and transmittance; and introducing a cutoff wavelength formula to explain the diffraction suppression phenomenon.

[0042] Reference Figure 5 The figure shows the diffraction results of the periodic silicon cylinder array on the dielectric substrate 1 under forward and backward illumination conditions, including the diffraction order and the transmission energy of the corresponding diffraction order. In the wavelength range of 300nm to 1100nm, Figure 5 As shown in (a), the diffraction orders supported by the transmittance under forward illumination are significantly more than the diffraction orders supported by the transmittance under backward illumination. Under backward illumination, the diffraction order that contributes to the transmittance is only 1. The reason for this phenomenon is that only incident light with a wavelength less than or equal to the array period can undergo effective diffraction. According to the calculation formula of the cut-off wavelength, the cut-off wavelength of the first-order diffraction wave in the dielectric substrate 1 is 1100nm. When the incident wavelength is less than 1100nm, no diffraction can occur. Therefore, under backward illumination conditions, only the (0, 0) order diffraction contributes to the transmittance, while other diffraction orders are suppressed. The specific formula for the cut-off wavelength is: ; (1) in, is the cut-off wavelength, For the cycle, and represents the diffraction order of the grating in the x and y directions, is the background refractive index of the diffraction space.

[0043] Further, Figure 5(b) shows the transmittance distribution due to diffraction under forward illumination. Higher-order diffraction waves are not shown in the figure due to their relatively weak intensity. Besides the (0, 0)-order diffraction wave, the (±1, 0)-order diffraction waves are the most intense and contribute most to the total transmittance. The (±1, 0)-order diffraction waves reach their peak intensity at a wavelength of 540 nm. Figure 5 (c) shows the transmittance caused by diffraction under backward illumination, and also gives the intensity of the (0, 0) order diffraction wave under forward illumination for comparison. Figure 5 (c) It can be seen that the transmittance caused by the (0, 0) order diffraction wave under forward illumination is equal to the total transmittance under backward illumination. Figure 5 The results show that the difference in transmittance under forward and backward illumination is mainly due to the high-order diffraction under forward illumination, especially the significant contribution of the (±1, 0)-order diffraction waves.

[0044] To further investigate the asymmetric light transmission phenomenon in the periodic silicon cylindrical nanoparticle array on dielectric substrate 1, the effects of two key structural parameters, the dielectric substrate material and the dielectric nanoparticle height (i.e., silicon cylinder height), were investigated in step S3. Through detailed analysis and discussion, the influence of these two parameters on the formation of maximum asymmetric light transmission and the wavelength position at which it occurs was revealed, and the physical mechanism involved was explained.

[0045] S310. Analyze the influence of dielectric substrate materials on asymmetric transmission phenomena. The details are as follows: According to the above research results on the asymmetric light transmission mechanism of dielectric nanoparticle arrays, the asymmetric light transmission phenomenon of the periodic silicon cylinder array on the dielectric substrate 1 is caused by the difference in diffraction orders under forward and backward illumination, and these diffraction orders are closely related to the refractive index of the dielectric substrate 1. In order to further analyze the influence of the dielectric substrate 1 on asymmetric light transmission, Figure 6 (a) and Figure 6 (b) Color maps showing the transmittance of a periodic silicon cylindrical nanoparticle array on a dielectric substrate 1 as a function of the refractive index of the dielectric substrate 1 under forward and backward illumination, respectively. The diameter and height of the silicon cylinders are set to 160 nm and 125 nm, respectively, and the array period is set to 200 nm.

[0046] Furthermore, forward illumination is defined as light incident from the air along the -z direction perpendicular to the current dielectric nanoparticle array into the dielectric substrate 1 region, and backward illumination is defined as light incident from the dielectric substrate 1 region along the +z direction perpendicular to the current dielectric nanoparticle array into the air. The structure of the embodiment of the present invention is a periodic nanoparticle array, and the evaluation method is preferably asymmetric subtraction (AS). Using asymmetric subtraction To intuitively evaluate the asymmetric light transmission efficiency of nanoperiodic arrays, the asymmetric difference The specific expression is: ; (2) in, and Respectively represent the transmittance under forward and backward illumination. It should be noted that compared with the prior art, the embodiment of the present invention calculates the asymmetric difference Although the formulas are different, all simulation results show that the forward transmittance is greater than the backward transmittance. Direct subtraction can simplify the calculation process.

[0047] Furthermore, the corresponding asymmetric difference is calculated according to the asymmetric difference formula, such as Figure 6 (c) shown.

[0048] Further, Figure 6 The horizontal axis of (a)-(c) represents the wavelength of the incident light (ranging from 300 nm to 1100 nm), and the vertical axis represents the refractive index of dielectric substrate 1 (ranging from 1 to 10). The color bar on the right side of the figure represents the range of transmittance, from 0 to 1. In this experiment, the diameter and height of the silicon cylinders are 160 nm and 125 nm, respectively, and the array period is 200 nm. When the refractive index of dielectric substrate 1 is 1, it represents a periodic array of silicon cylinders placed in air, without any additional substrate. Figure 6 The short dashed lines marked as "(0, ±1) & (±1, 0)sub" in (a)-(c) fit the relationship between the cutoff wavelength of the first-order diffraction wave inside the dielectric substrate 1 and the substrate refractive index, which is calculated by formula (1). Above the short dashed lines, Figure 6 In (a), except for wavelengths less than about 400 nm, the transmittance of forward illumination is greater than 0.5. Figure 6 In (b), when the wavelength is greater than about 600nm, the transmittance of backward illumination is greater than 0.5. In general, the transmittance under forward illumination is generally higher than that under backward illumination. Figure 6 (c) It can be seen that the region with the largest difference in transmittance under forward and backward illumination is mainly concentrated in the wavelength range of 500nm to 600nm. In this wavelength range, the transmittance under backward illumination is close to zero, showing significant asymmetric light transmission characteristics.

[0049] Furthermore, if Figure 6As shown in (c), when the substrate's refractive index is 1, due to the geometric symmetry of the nanoperiodic array, there is no significant difference in transmittance under forward and backward illumination from both incident directions. However, it is worth noting that in prior art, the nanoparticles in the periodic array are designed with geometrically asymmetric shapes to achieve asymmetric light transmission without a substrate. When these asymmetric nanoparticles are placed on a substrate, the asymmetric environment surrounding the nanoparticles further exacerbates the difference in transmittance under forward and backward illumination. This phenomenon stems from the Lorentz symmetry of reciprocal structures: in symmetric structures, the transmittance caused by zero-order diffraction is the same under forward and backward illumination. This is one of the main challenges in realizing asymmetric light transmission structures based on high-order diffraction. In most cases, prior art either ignores the high zero-order diffraction efficiency or nearly eliminates it through directional Mie scattering in complex asymmetric structures. Unlike these prior art methods, the embodiments of the present invention achieve efficient asymmetric light transmission through symmetric nanostructures. Specifically, this is achieved by significantly reducing the transmittance induced by zero-order diffraction in the nanostructure, especially at a wavelength of 540 nm where maximum asymmetric light transmission is achieved.

[0050] Furthermore, when the substrate refractive index is 1.5, the cutoff wavelength of the first-order diffraction wave inside the substrate is 300nm (the calculation formula is 200nm×1.5, where 200nm is the array period, obtained from formula (1)). At a wavelength of 300nm, the asymmetric difference is only 0.011. Figure 6 (c) is not obvious. When the substrate refractive index is less than 6, the asymmetric light transmission cutoff wavelength for each dielectric substrate 1 corresponds to the cutoff wavelength of the first-order diffraction wave within that substrate. As the refractive index increases, the bandwidth of asymmetric light transmission gradually widens. When the refractive index of dielectric substrate 1 exceeds 6 and continues to increase, the cutoff wavelength of asymmetric light transmission exceeds 1100 nm, which is beyond the scope of the present invention. This phenomenon is caused by the difference in diffraction orders under forward and backward illumination.

[0051] In order to conduct in-depth research Figure 6 (c) Details of the maximum asymmetric light transmission phenomenon in the region, Figure 6 (d) Yes Figure 6 The dotted box area in (c) is enlarged and the corresponding asymmetric difference is marked. The wavelength range of the selected dotted box is 520nm to 570nm, the substrate refractive index range is 4 to 10, and the color bar on the right side of the figure indicates that the transmittance range is 0.8 to 0.9. Figure 6As can be seen in (d), the maximum asymmetric light transmission of each dielectric substrate 1 reaches a peak at a wavelength of 540nm (as shown in the solid line frame). This phenomenon is mainly attributed to the strong scattering characteristics of the silicon cylinder at this wavelength and the (±1, 0) order diffraction waves reaching their peak at 540nm. In addition, as Figure 6 As shown in the solid-line box in (d), when the wavelength is fixed at 540 nm, the asymmetric difference first increases and then decreases with the increase in the refractive index of the dielectric substrate 1. Specifically, when the substrate refractive index is 5.5, the asymmetric difference reaches a maximum value of 0.894 (as shown in the dashed-line box).

[0052] In summary, Figure 6 The results of (a)-(c) show that when the refractive index of the dielectric substrate 1 is greater than 3, the asymmetric light transmission phenomenon of the periodic silicon cylindrical nanoparticle array on the dielectric substrate 1 tends to be stable and no longer changes with further increase in the refractive index of the dielectric substrate, that is, the asymmetric transmission phenomenon of the optical device tends to be stable. Figure 6 (d) further reveals that when the refractive index of the substrate is greater than 4, the wavelength position of each dielectric substrate 1 when obtaining the maximum asymmetric light transmission remains unchanged and does not change with the change of the refractive index of the dielectric substrate.

[0053] S320, the height of the silicon cylinder not only directly affects the transmittance, but also affects the transmission under different lighting directions, which in turn plays a key role in the efficiency of asymmetric light transmission. Therefore, the impact of silicon cylinder height on asymmetric light transmission is analyzed as follows: Figure 7 (a) and Figure 7 (b) shows the color map of the transmittance of the silicon cylinder array on the dielectric substrate 1 under forward and backward illumination, respectively, as a function of the silicon cylinder height. In the experiment, the diameter of the silicon cylinder is 160nm, the array period is 200nm, the refractive index of the dielectric substrate 1 is 5.5, and the height of the silicon cylinder is studied in the range of 100nm to 150nm. The asymmetric difference calculated by formula (2) is as follows: Figure 7 (c) The horizontal axis in the figure is the wavelength of the incident light (300nm to 1100nm), and the color bar on the right side of the figure represents the range of transmittance from 0 to 1.

[0054] Further, from Figure 7 (a) It can be seen that, except for wavelengths less than 400nm, the transmittance under forward illumination is greater than 0.5. Figure 7 In (b), when the wavelength exceeds 600nm, the transmittance under backward illumination is greater than 0.5. In general, the transmittance under forward illumination is generally higher than that under backward illumination. The areas with large differences in transmittance between forward and backward illumination are mainly concentrated in Figure 7(c) shows the wavelength range of 450nm to 650nm. In this wavelength range, the transmittance under backward illumination is close to zero, showing significant asymmetric light transmission characteristics.

[0055] Furthermore, in order to conduct in-depth research Figure 7 (c) The maximum asymmetric light transmission phenomenon in the region, Figure 7 (d) Yes Figure 7 The dotted box area in (c) is magnified, with the wavelength range from 500nm to 570nm, and the corresponding asymmetric difference is marked. The height of the silicon cylinder is studied in the range of 100nm to 150nm, and the color bar on the right side of the figure represents the transmittance range from 0.5 to 0.9. Figure 7 As can be seen in (d), for each silicon cylinder height, the asymmetric difference first increases and then decreases with increasing wavelength. When the silicon cylinder height is 100nm and 110nm, the maximum asymmetric difference is 0.868 and 0.885, respectively, and the corresponding wavelength is 530nm. As the silicon cylinder height increases further, the wavelength at which maximum asymmetric light transmission is achieved redshifts. This phenomenon is due to the fact that increasing the silicon cylinder height leads to an increase in its volume and enhanced polarization, which causes a redshift in the resonant wavelength.

[0056] In addition, as the height of the silicon cylinder increases, the maximum asymmetric difference of the array at each height shows a trend of first increasing and then decreasing. Specifically, when the height of the silicon cylinder is 125nm, n sub =5.5, the asymmetric difference of the periodic silicon cylinder array reaches a maximum value of 0.894 (as shown in the dotted box).

[0057] and Figure 6 similar, Figure 7 (a)-(c) show that the asymmetric light transmission phenomenon of the periodic silicon cylinder array on the dielectric substrate 1 does not change significantly with the change of the silicon cylinder height to a certain extent. Figure 7 As shown in (d), the wavelength at which the maximum asymmetric light transmission is achieved red-shifts as the height of the silicon cylinder increases. Figure 6 and Figure 7 Results show that asymmetric light transmission maintains high efficiency even when the refractive index of the dielectric substrate 1 and the height of the silicon cylinders vary. Furthermore, the wavelength at which maximum asymmetric light transmission occurs does not require specific substrate material, but can be precisely controlled by adjusting the height of the silicon cylinders. These characteristics give this nanoperiodic array greater flexibility and adaptability in practical applications, with broad potential applications in fields such as radiative cooling, optical isolators, photovoltaic devices, and sensors.

[0058] The embodiment of the present invention uses numerical simulation methods to study the high-efficiency asymmetric light transmission performance of a periodic silicon cylindrical nanoparticle array on a dielectric substrate 1 within a wide wavelength range of 300nm to 1100nm. This performance is due to the difference in diffraction orders under forward and backward illumination. The results show that at a wavelength of 540nm, the maximum asymmetric difference of the nanoperiodic array can reach 0.894, the transmittance under forward illumination is as high as 0.898, and the transmittance under backward illumination is almost zero. In addition, the nanoperiodic array is insensitive to the polarization state of the incident light and has excellent light capture characteristics: under forward illumination, the transmittance is high, the absorption rate and reflectivity are low; under backward illumination, the transmittance is almost zero.

[0059] The effects of the dielectric substrate material and silicon pillar height on asymmetric light transmission were further analyzed, and the underlying physical mechanisms were explored. The results demonstrate that efficient asymmetric light transmission is robust to variations in the dielectric substrate refractive index and silicon pillar height. When the refractive index of dielectric substrate 1 varies between 4 and 10, the structure consistently achieves a maximum asymmetry difference of approximately 0.9 at a wavelength of 540 nm. When the silicon pillar height varies between 100 nm and 150 nm, the maximum asymmetry difference remains constant at approximately 0.9. However, the wavelength at which maximum asymmetric light transmission is achieved is only sensitive to variations in silicon pillar height. This wavelength redshifts with increasing silicon pillar height. For example, when the silicon pillar height increases from 100 nm to 150 nm, the wavelength at which maximum asymmetric light transmission is achieved redshifts from 530 nm to 560 nm.

[0060] In this embodiment of the present invention, optical simulation software is used to model nanoparticles of various dielectric materials, shapes, and sizes. The asymmetric light transmission behavior of these particles in specific array configurations is studied, as well as how different diffraction orders affect this phenomenon. Simulations predict the impact of different structural parameters on asymmetric light transmission performance, optimizing the particle geometry and arrangement. Based on the simulation results, the dielectric nanoparticle shape, size, and period that maximize asymmetric light transmission are selected. The array period is adjusted to optimize the directional transmission capability of light and enhance the transmission efficiency of specific wavelengths.

[0061] The dielectric nanoparticle arrays of the present invention exhibit light-trapping and anti-reflection properties, which help increase the light absorption efficiency of photovoltaic devices and improve the optical performance of display devices. By establishing a periodic array model and analyzing asymmetric transmission mechanisms, the structural parameters were optimized. Furthermore, the present invention provides valuable insights for the theoretical research and practical application of asymmetric light transmission in photovoltaic devices, display devices, and optical isolation. Example 3

[0062] An embodiment of the present invention provides an electronic device, including the asymmetric transmission optical device provided in the first embodiment.

[0063] In this embodiment, the optical device is configured as a photodiode, and the electronic device includes the photodiode. This high-performance photodiode device, similar to a photodiode, exhibits extremely important application value in the development of next-generation all-optical computing and processing systems due to its unique directional selectivity. The dielectric nanoparticle array on the dielectric substrate 1 proposed in this embodiment not only achieves high-efficiency asymmetric light transmission but also has light capture and anti-reflection properties, making it promising for use as a photodiode in applications such as improving the efficiency of photovoltaic devices and display device performance.

[0064] Furthermore, in order to preliminarily evaluate the performance of the nanoperiodic array as a photodiode, this embodiment will use a simple model to simulate Figure 1 Photodiode performance of the structure shown, focusing on its light trapping effect.

[0065] like Figure 8 As shown in (a), the model consists of a periodic silicon cylinder array (i.e., photodiode) on a dielectric substrate 1 and a gold film 3 under the substrate. Figure 8 (b) shows the process of light irradiated from the top being diffracted in the structure and reflected at the interface of the gold film 3. The structural parameters in the model are consistent with the data from the analysis of the asymmetric light transmission mechanism of the dielectric nanoparticle array: the diameter and height of the silicon cylinder are 160nm and 125nm respectively, the array period is 200nm, the refractive index of the dielectric substrate 1 is 5.5, and the substrate thickness is 100nm. Figure 3 As can be seen from the transmittance curve in (a), the periodic silicon cylinder array on the dielectric substrate 1 can allow most of the light to be transmitted into the dielectric substrate 1 during initial illumination, while effectively limiting the escape of light.

[0066] like Figure 9 As shown in (a), when the gold film 3 is only covered by a 100nm thick dielectric substrate 1 (refractive index 5.5), the reflectivity in certain specific wavelength bands is significantly lower than that of the pure gold film 3 due to the Fabry-Perot cavity resonance and light interference effects. However, in the entire wavelength range of 350nm to 1100nm, there is no obvious overall decrease in reflectivity. Specifically, Figure 9 The results in (a) show that the average reflectivity of the pure gold film 3 is about 0.8317, while the average reflectivity of the gold film 3 covered with the dielectric substrate 1 is about 0.8338, which are very close. However, when a photodiode (such as Figure 8 After the reflection is completed, the reflectivity in the entire wavelength range is significantly lower than that of the pure gold film 3, and the average reflectivity is reduced to 0.6562. Figure 9It can also be observed in (a) that the reflectivity drops significantly at multiple wavelengths, especially at 470nm and 630nm, where the reflectivity is almost close to zero. The above results show that the asymmetric light transmission characteristics of the photodiode can effectively capture light, thereby significantly reducing the reflectivity and playing the role of light trapping. Figure 9 In the figure, Au film indicates a gold film; Au+sub indicates that the gold film is covered with a dielectric substrate 1; Au+optical diode indicates that an optical diode is placed on the gold film.

[0067] Furthermore, research on the influence of dielectric substrate 1's material has shown that when the refractive index of dielectric substrate 1 is greater than 3, the asymmetric light transmission phenomenon of the periodic silicon cylinder array on dielectric substrate 1 no longer significantly changes with changes in the refractive index of dielectric substrate 1. Even with changes in the refractive index of dielectric substrate 1, asymmetric light transmission maintains high efficiency. Therefore, the photodiode proposed in this embodiment can maintain excellent light capture performance even after changing the dielectric substrate material.

[0068] Further, Figure 9 (b)-(d) show the reflectivity characteristics of the photodiode placed on the gold film 3 when the refractive index of the dielectric substrate 1 is 5, 6, and 6.5 respectively. In order to facilitate comparison with the pure gold film and other conditions, the reflectivity of the pure gold film and the reflectivity of the gold film 3 covered with the dielectric substrate 1 of the corresponding refractive index are also shown in the figure. Figure 9 (a) Stay consistent. Figure 9 (b) It can be seen that when the refractive index of the dielectric substrate 1 is 5, the average reflectivity of the gold film 3 covering the dielectric substrate 1 is about 0.8418.

[0069] Further, in Figure 9 (c) and Figure 9 In (d), the average reflectivity of the gold film 3 covered with the dielectric substrate 1 with a refractive index of 6 and 6.5 is approximately 0.8476 and 0.8594, respectively, which is a certain degree higher than the average reflectivity of the pure gold film (approximately 0.8317). However, when the photodiode is placed on the surface of the gold film 3, the reflectivity across the entire wavelength range is generally reduced (except for a few wavelengths). Specifically, Figure 9 The average reflectance shown in (b)-(d) decreases to 0.676, 0.6571, and 0.6605, respectively.

[0070] Figure 9 Results show that photodiodes based on dielectric nanoparticle arrays on dielectric substrate 1 exhibit excellent light trapping performance, with no special requirements for the material of the dielectric substrate 1. These properties enhance the compatibility and compatibility of the photodiode with a variety of devices, enabling greater flexibility and broad adaptability in practical applications.

[0071] Based on the optical properties described in Example 1 (i.e., asymmetric light transmission and light capture), this embodiment designs a photodiode for light trapping and anti-reflection. This photodiode exhibits excellent optical performance, requires low precision in structural parameters, and can significantly reduce average reflectivity over a wide wavelength range. Furthermore, this photodiode can be widely used in optoelectronic devices such as solar cells, effectively reducing light reflection from surfaces, thereby significantly enhancing the device's light absorption efficiency and further improving its photoelectric conversion performance.

[0072] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0073] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0074] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0075] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0076] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. An optical device with asymmetric transmission, characterized in that: include: A dielectric nanoparticle array comprising a plurality of dielectric nanoparticles, each of the dielectric nanoparticles being periodically arranged at a preset spacing; wherein the height of the dielectric nanoparticles is 60 nm to 150 nm; The dielectric substrate is used to support the dielectric nanoparticle array and is arranged below the dielectric nanoparticle array.

2. The asymmetric transmission optical device according to claim 1, characterized in that: The dielectric nanoparticles are in the shape of axisymmetric cylinders.

3. The asymmetric transmission optical device according to claim 1, characterized in that: The material of the dielectric nanoparticles is at least one of silicon, titanium dioxide, silicon nitride, and gallium arsenide.

4. The asymmetric transmission optical device according to claim 1, characterized in that: The refractive index of the dielectric substrate is 1.5-10.

5. The asymmetric transmission optical device according to claim 1, characterized in that: The preset distances between adjacent dielectric nanoparticles are the same.

6. The asymmetric transmission optical device according to claim 1, characterized in that: The preset spacing is 120 nm to 800 nm.

7. A method for testing an asymmetric transmission optical device, characterized in that: include: S1. According to the asymmetric transmission optical device according to any one of claims 1 to 6, establishing a periodic array model, setting structural parameters of the periodic array model, and obtaining an optimal periodic array model; S2. Setting forward illumination and backward illumination on the optimal periodic array model respectively; performing asymmetric transmission mechanism analysis under the forward illumination and backward illumination to obtain the relationship between different orders of diffraction and transmittance of the optical device; S3. Analyzing the relationship between the structural parameters and the asymmetric transmission phenomenon based on the relationship between the different diffraction orders and the transmittance; S4. Obtaining optimal structural parameters for asymmetric transmission based on the relationship between the different diffraction orders and transmittance and the relationship between the structural parameters and the asymmetric transmission phenomenon.

8. The method for testing an asymmetric transmission optical device according to claim 7, wherein: In S2, forward illumination and backward illumination are respectively set on the optimal periodic array model; and the steps of performing asymmetric transmission mechanism analysis under the forward illumination and backward illumination are as follows: According to the periodic array model, simulation analysis is performed on the transmittance of the optical device under forward and backward illumination conditions; By adjusting different wavelengths, analyzing the diffraction orders and the transmission energy of the corresponding diffraction orders, the relationship between the different diffraction orders and the transmittance is obtained; wherein, the process of analyzing the diffraction orders and the transmission energy of the corresponding diffraction orders includes introducing a cutoff wavelength formula to explain the diffraction suppression phenomenon.

9. The method for testing an asymmetric transmission optical device according to claim 7, wherein: Said S3, the relationship between the structural parameters and the asymmetric transmission phenomenon includes: when the refractive index of the dielectric substrate of the optical device is greater than 3, the asymmetric transmission phenomenon of the optical device tends to be stable; when the refractive index of the dielectric substrate is greater than 4, the wavelength position when the optical device obtains maximum asymmetric light transmission remains unchanged.

10. An electronic device, characterized in that: An asymmetric transmission optical device comprising the asymmetric transmission optical device according to any one of claims 1 to 6.

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