Orthogonal polarized light converter based on reflective dielectric metasurface

Abstract

The application belongs to the technical field of optical super surface, and particularly relates to a crossed polarized light converter based on a reflective dielectric super surface; a dielectric super surface functional layer is arranged on the upper surface of a dielectric layer, and a metal reflection layer is arranged on the lower surface of the dielectric layer; the dielectric super surface functional layer is composed of a periodic array of elliptical dielectric nanocolumns, and is used for realizing the polarization state control of incident light based on Mie resonance; when X polarized light enters the array of elliptical dielectric nanocolumns, the array of elliptical dielectric nanocolumns performs phase modulation on the entering X polarized light based on Mie resonance, and obtains crossed Y polarized light, so as to meet the demand of modern photonics platform on device thinning, miniaturization and monolithic integrated design.

Description

Technical Field

[0001] This invention relates to the field of optical metasurface technology, and more particularly to an orthogonal polarization converter based on a reflective dielectric metasurface. Background Technology

[0002] With the urgent need for high-performance polarization control devices in integrated photonics and quantum information technologies, existing orthogonal polarization converters still face significant technical challenges. In traditional optical systems, the core mechanism of controlling the polarization state of light using birefringent waveplates or shaping wavefronts using lenses relies on the light wave undergoing a sufficiently long propagation path within the material. For birefringent waveplates, the conversion of the target polarization state requires the beam to propagate a specific distance within the crystal to accumulate a sufficient phase difference between the ordinary (o) and extraordinary (e) rays. Similarly, lenses achieve beam convergence or divergence essentially because their curved surface structure or refractive index gradient causes the light waves in the center and edge regions of the beam to accumulate the required phase difference as they pass through materials of different thicknesses. This fundamental dependence on physical propagation distance and corresponding material thickness means that traditional components inevitably require a considerable volume and physical thickness for both polarization control and complex spatial phase modulation. This characteristic becomes a major obstacle to their application in modern photonics platforms that pursue high integration and miniaturization, making it difficult to meet the demands of these platforms for thinner, smaller, and monolithically integrated device designs. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides an orthogonal polarization converter based on a reflective dielectric metasurface.

[0004] The present invention provides an orthogonal polarization converter based on a reflective dielectric metasurface, comprising: a dielectric metasurface functional layer, a dielectric layer, and a metal reflective layer;

[0005] The dielectric metasurface functional layer is disposed on the upper surface of the dielectric layer, and the metal reflective layer is disposed on the lower surface of the dielectric layer;

[0006] The dielectric metasurface functional layer is composed of a periodically arranged array of elliptical dielectric nanopillars, which is used to control the polarization state of incident light based on Mie resonance.

[0007] When X-polarized light enters the elliptical dielectric nanopillar array, the array modulates the phase of the incoming X-polarized light based on Mie resonance, resulting in orthogonal Y-polarized light.

[0008] In one possible implementation, the elliptical dielectric nanopillar array is made of silicon.

[0009] In one possible implementation, the dielectric layer is made of silicon dioxide.

[0010] In one possible implementation, the thickness of the dielectric layer is 100~300nm.

[0011] In one possible implementation, the metal reflective layer is made of any one of gold, silver, aluminum, or copper.

[0012] In one possible implementation, the metal reflective layer is an aluminum reflective layer with a thickness of 100~300nm.

[0013] In one possible implementation, the cross-section of the nanopillars in the elliptical dielectric nanopillar array is elliptical, and the height of the nanopillars is 700~1000nm.

[0014] The cross-section of the nanopillar has a major axis length of 100~300nm, a minor axis length of 80~200nm, and an axis ratio between the major and minor axes of 1.2:1~1.5:1.

[0015] In one possible implementation, the long axis of the cross-section of the nanopillar forms an angle of 45° ± 5° with the X-polarization direction of the incident light.

[0016] In one possible implementation, the period of the elliptical dielectric nanopillar array is 650 nm.

[0017] In one possible implementation, the wavelength of the incident light is 1.53 μm to 1.66 μm.

[0018] The technical solution provided by this invention has at least the following beneficial effects:

[0019] By combining a dielectric metasurface functional layer, a dielectric layer, and a metal reflective layer, and defining the dielectric metasurface functional layer as a periodically arranged elliptical dielectric nanopillar array, when X-polarized light enters the elliptical dielectric nanopillar array, the elliptical dielectric nanopillar array modulates the phase of the incoming X-polarized light based on Mie resonance to obtain Y-polarized light. This achieves a new optical conversion technology that can meet the requirements of highly integrated and miniaturized modern photonics platforms for device thinning, miniaturization, and monolithic integrated design. Attached Figure Description

[0020] Figure 1 This is a side view of an orthogonal polarization converter based on a reflective dielectric metasurface, as provided in an embodiment of this application.

[0021] Figure 2 This is a three-dimensional view of the square lattice in the orthogonal polarization converter provided in the embodiments of this application;

[0022] Figure 3 This is the corresponding embodiment provided in this application. Figure 2 A top view of an orthogonal polarization converter;

[0023] Figure 4 This is a schematic diagram illustrating the relationship between the reflection coefficient and wavelength under different polarization states provided in the embodiments of this application;

[0024] Figure 5 This is a schematic diagram of PCR efficiency under X-polarization excitation provided in the embodiments of this application;

[0025] Figure 6 This is a schematic diagram illustrating the relationship between phase difference and phase and wavelength of polarized light provided in the embodiments of this application;

[0026] Figure 7 This is a three-dimensional diagram of the regular hexagonal lattice in the orthogonal polarization converter provided in the embodiments of this application;

[0027] Figure 8 This is the corresponding embodiment provided in this application. Figure 7 A top view of an orthogonal polarization converter;

[0028] Figure 9 This is a schematic diagram illustrating the effect of different reflective layer materials on the PCR efficiency of an orthogonal polarization converter under X-polarization, as provided in the embodiments of this application.

[0029] Explanation of reference numerals in the attached figures:

[0030] 10. Dielectric metasurface functional layer; 20. Dielectric layer; 30. Metal reflective layer. Detailed Implementation

[0031] To enhance understanding of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. These embodiments are only used to explain the invention and do not limit the scope of protection of the invention.

[0032] Please refer to Figures 1 to 9 The present invention provides an orthogonal polarization converter based on a reflective dielectric metasurface, comprising: a dielectric metasurface functional layer 10, a dielectric layer 20, and a metal reflective layer 30;

[0033] The dielectric metasurface functional layer 10 is disposed on the upper surface of the dielectric layer 20, and the metal reflective layer 30 is disposed on the lower surface of the dielectric layer 20.

[0034] The dielectric metasurface functional layer 10 is composed of a periodically arranged elliptical dielectric nanopillar array, which is used to control the polarization state of incident light based on Mie resonance.

[0035] When X-polarized light enters the elliptical dielectric nanopillar array, the array modulates the phase of the incoming X-polarized light based on Mie resonance, resulting in orthogonal Y-polarized light.

[0036] In this embodiment, the high-refractive-index dielectric metasurface functional layer 10 adopts a single-layer subwavelength structure design to achieve polarization state control. The elliptical dielectric nanopillar array consists of several dielectric nanopillars with elliptical cross-sections. The major axis of these nanopillars forms a certain angle θ (e.g., 45°) with the periodic arrangement direction. Mie resonance can induce a phase difference when light of different polarization states passes through, thereby achieving polarization state control. By adjusting the ratio of the major to minor axes of the dielectric nanopillars, the response of the nanopillars to different polarized light can be precisely adjusted. The anisotropic characteristics of this design allow the nanopillars to effectively decompose and control the polarization direction of light in a specified wavelength band, achieving modulation or conversion of the input light. When light passes through these nanopillars, the interaction between the light wave and the material results in a phase difference (π phase difference). Therefore, one of the main functions of the dielectric metasurface functional layer 10 is to control the polarization direction and the conversion between X-polarization and Y-polarization states of light by adjusting the phase of the light.

[0037] The low-refractive-index material dielectric layer 20 is located between the high-refractive-index dielectric metasurface functional layer 10 and the metal reflective layer 30. Its main functions are: reducing losses, as the low-refractive-index material has lower optical losses, which can effectively reduce the absorption or scattering losses that light may encounter during propagation; increasing optical path, as controlling the thickness of the low-refractive-index material layer can adjust the propagation path of light in the system, thereby regulating the phase change of light at different wavelengths and optimizing the efficiency of reflection and transmission; and optical matching, as the refractive index of the low-refractive-index material dielectric layer 20 has good optical matching with the refractive index of the dielectric nanopillar array and the metal reflective layer 30, which can reduce interface reflection and light loss and improve the overall optical performance.

[0038] The metallic reflective layer 30, composed of metallic materials, provides highly efficient reflection performance, especially within the target wavelength band (C+L communication band). Metal, as a reflective material, exhibits low absorption loss and ensures high reflectivity, particularly for visible and near-infrared wavelengths. The metallic reflective layer 30 not only provides the necessary reflection effect but also works synergistically with the dielectric metasurface functional layer 10. The high-refractive-index dielectric metasurface functional layer 10 modulates the polarization state and phase of light, while the metallic reflective layer 30 is responsible for reflecting both modulated and unmodulated light back in the correct direction. This synergistic effect effectively improves the overall efficiency of the system, ensuring full utilization of light in reflective designs. The combination of the metallic reflective layer 30 and the low-refractive-index dielectric layer 20 ensures the advantages of reflective design within the target wavelength band, effectively enhancing the system's operability and stability.

[0039] It should be noted that the orthogonal polarization converter in this application exhibits superior performance (polarization conversion efficiency PCR > 90%) in the C+L communication band and possesses low-loss characteristics. The orthogonal polarization converter primarily utilizes a periodically arranged array of high-refractive-index elliptical dielectric nanopillars to achieve precise orthogonal conversion of X-polarized light to Y-polarized light. Its working principle leverages the anisotropy generated by the Mie resonance supported by the high-refractive-index dielectric nanopillars to induce a critical phase difference (π) between the long and short axis components of the incident light field. A highly reflective metal substrate, i.e., the metal reflective layer 30, and an optimized dielectric layer 20 work together to ensure efficient reflection of the converted light and minimize propagation loss, thus achieving a perfect combination of high efficiency and low loss. This efficient, reliable, and easily manufactured polarization conversion technology provides a powerful tool for polarization state manipulation in optical communication systems, quantum communication devices, and various high-precision optical devices.

[0040] In one specific implementation, when using an orthogonal polarization converter for polarization conversion, a periodically arranged elliptical high-refractive-index dielectric nanopillar array is used to precisely modulate the polarized light through the anisotropic properties of the material. When X-polarized light is incident on the high-refractive-index dielectric metasurface functional layer 10 (an array composed of high-refractive-index dielectric material nanopillars), the light field is decomposed into two light field components along the long and short axes during the interaction of the high-refractive-index dielectric nanopillars. Due to the geometry and material properties of the high-refractive-index dielectric nanopillars, these two light fields generate a phase difference of π during propagation. This phase difference converts the original X-polarized light into Y-polarized light, thereby achieving orthogonal polarization conversion. In this structure, the metal reflective layer 30 ensures that the Y-polarized light partially transmitted to the metal reflective layer 30 after conversion can be effectively reflected back through efficient reflection, reducing light loss. At the same time, the high reflectivity of the metal reflective layer 30 improves the optical efficiency of the entire system, especially in the C+L band, where the role of the metal reflective layer 30 is particularly important. The low-refractive-index dielectric layer 20, located between the high-refractive-index dielectric metasurface functional layer 10 and the metal reflective layer 30, plays a crucial role in reducing losses and adjusting the phase of light. By adjusting the thickness and refractive index of the low-refractive-index dielectric layer 20, the propagation path of light between layers can be precisely controlled, reducing interface reflection and light loss, and further improving polarization conversion efficiency. This design not only achieves a polarization conversion efficiency (PCR) of over 90% in the C+L communication band but also exhibits low material loss, effectively avoiding the energy loss problem in traditional designs. Furthermore, the good matching between the high-refractive-index dielectric material and the low-refractive-index dielectric layer 20 ensures the stability and high efficiency of the system, while the material processing technology is simple and easy to achieve large-scale integration. In summary, this polarization conversion scheme is an efficient and low-loss solution that can achieve high-performance polarization state adjustment and conversion in communication systems, and has broad application prospects.

[0041] In one possible implementation, the elliptical dielectric nanopillar array is made of silicon.

[0042] In this embodiment, the elliptical dielectric nanopillar array is an elliptical silicon nanopillar array, which can be directly formed on the Si thin film through a single-step photolithography and etching process. The entire manufacturing process is simpler and faster, and can effectively reduce optical defects and manufacturing errors, thereby improving product consistency and reliability. This manufacturing process does not require complex three-dimensional stacking or multi-layer alignment processes, greatly reducing the difficulty and cost of manufacturing.

[0043] In one possible implementation, the dielectric layer 20 is made of silicon dioxide.

[0044] In this embodiment, both the silicon material used in the elliptical dielectric nanopillar array and the silicon dioxide material used in the dielectric layer 20 are standard semiconductor process materials, enabling the orthogonal polarization converter to seamlessly integrate with existing silicon photonics manufacturing processes. Specifically, the manufacturing processes of the orthogonal polarization converter (including thin film deposition, nanoimprinting, photolithography, etching, etc.) are fully compatible with modern complementary metal-oxide-semiconductor (CMOS) technology and silicon photonics (Si Photonics) integration manufacturing processes. Therefore, this orthogonal polarization converter can be directly processed and integrated on standard Si wafers, providing feasibility for the commercial large-scale production of the device and enabling mass production at low cost. Simultaneously, silicon (Si) and silicon dioxide (SiO2) have extremely low optical loss characteristics, effectively improving the overall optical efficiency of the device. Si and SiO2 materials exhibit excellent transmission characteristics within the target wavelength band, enabling efficient transmission of optical signals and reducing optical energy loss. This not only improves polarization conversion efficiency but also ensures low insertion loss.

[0045] In one possible implementation, the thickness of the dielectric layer 20 is 100~300 nm.

[0046] In one possible implementation, the metal reflective layer 30 is made of any one of gold, silver, aluminum, or copper.

[0047] In one possible implementation, the metal reflective layer 30 is an aluminum reflective layer with a thickness of 100~300nm.

[0048] In one possible implementation, the cross-section of the nanopillars in the elliptical dielectric nanopillar array is elliptical, and the height of the nanopillars is 700~1000nm.

[0049] The cross-section of the nanopillar has a major axis length of 100~300nm, a minor axis length of 80~200nm, and an axis ratio between the major and minor axes of 1.2:1~1.5:1.

[0050] In one possible implementation, the long axis of the cross-section of the nanopillar forms an angle of 45° ± 5° with the X-polarization direction of the incident light.

[0051] In one possible implementation, the period of the elliptical dielectric nanopillar array is 650 nm.

[0052] In one possible implementation, the wavelength of the incident light is 1.53 μm to 1.66 μm.

[0053] In one specific implementation, such as Figure 2 An orthogonal polarization converter can be composed of several square lattices. Figure 3This is a top view of the corresponding orthogonal polarization converter. The elliptical dielectric nanopillars are made of silicon and are denoted as elliptical silicon nanopillars. The dielectric layer 20 is made of silicon dioxide and is denoted as the SiO2 dielectric layer. The metal reflective layer 30 is made of aluminum and is denoted as the aluminum reflective layer. The thickness of the aluminum reflective layer is 100~300nm, used to provide a high reflectivity substrate (>95%). The thickness of the SiO2 dielectric layer is 100~300nm, located above the metal reflective layer 30. The elliptical high refractive index dielectric nanopillar array is periodically arranged on the upper surface of the SiO2 dielectric layer. Each nanopillar has an elliptical cross-section, with a height H=700~1000nm, a major axis length La=100~300nm, a minor axis length Lb=80~200nm, an axial ratio La / Lb=1.2:1~1.5:1, and the major axis direction forms an angle of 45°±5° with the incident X-polarization direction. The array period P = 650 nm (satisfying the subwavelength condition P < λ). The overall thickness of the orthogonal polarization converter is less than 1 μm. This miniaturized design not only reduces material usage and production costs but also enables higher integration, allowing for easier integration into existing silicon-based photonic chips or optoelectronic integrated circuits (OEICs). This integration advantage makes the device more flexible in practical applications, suitable for close integration with other optical components (such as optical modulators and photodetectors), further improving the overall system performance and functional density. Due to its simple three-layer planar structure and subwavelength size, this device is ideally suited for on-chip photonic integrated systems. It can be monolithically integrated as a functional module into existing silicon-based photonic chips or optoelectronic integrated circuits, demonstrating strong adaptability and potential, especially in applications such as polarization diversity reception, polarization state modulation, and optical switching. For example, in modern communication systems, polarization diversity reception technology is crucial for improving system capacity and reliability, and the device of this invention provides an efficient and low-cost solution in this field.

[0054] For a metasurface waveplate, i.e. an elliptical silicon nanopillar, such as Figure 2 If we establish a coordinate system xoy with the horizontal and vertical lines as references in a horizontal plane, and a coordinate system uov with the major and minor axes of the elliptical silicon nanopillar as references, where o is the origin of both coordinate systems and also the center of the elliptical silicon nanopillar, then the angle between the u-axis and the x-axis is θ. Due to the birefringence effect of the elliptical silicon nanopillar, linearly polarized light incident along the x-axis decomposes along the major and minor axes of the elliptical silicon nanopillar. Furthermore, due to the phase difference δ introduced by the metasurface waveplate, the polarization of the incident light will be deflected accordingly based on the angles θ and δ. This process can be explained using the Jones matrix. Projecting any incident polarized light -1 onto the u-axis and v-axis respectively, we can see that:

[0055]

[0056] If a phase difference δ is introduced, the light emitted from the metasurface waveplate can be expressed as:

[0057]

[0058] Projecting back onto the x and y axes, we get:

[0059]

[0060]

[0061] Therefore, the Jones matrix of this metasurface waveplate can be expressed as:

[0062]

[0063] Here, consider a metasurface with a phase difference of π, i.e., a half-wave plate. If the angle between the major axis and the x-axis is 45°, then when linearly polarized light with polarization along the x-axis is incident:

[0064]

[0065] It can be observed that the polarization direction of the emitted light changes from the x-axis to the y-axis.

[0066] When incident X-ray polarized light passes through an array of elliptical silicon nanopillars, the anisotropic nature of the nanopillars causes different refraction and propagation characteristics in the two directions, resulting in differences in the propagation speed, phase, and amplitude of the light field along the major and minor axes. This difference introduces a phase difference Δφ, which arises from the different propagation characteristics of the light field within the elliptical silicon nanopillars. The magnitude of this phase difference is closely related to the geometry of the silicon nanopillars (such as the ratio of the major and minor axes of the ellipse), the wavelength of the incident light, and the anisotropic properties of silicon.

[0067] Figure 4The figure illustrates the variation of reflectance coefficient with wavelength under different polarization states. Four reflectance coefficient curves represent different polarization states: Rxy (black curve), Rxx (blue curve), Ryx (red dashed curve), and Ryy (pink dashed curve). The figure shows that within the wavelength range of 1.53 μm to 1.66 μm (highlighted gray area), |Rxy|,|Ryx| >> |Rxx|,|Ryy|. At this point, the original X-polarized light is effectively recombined into Y-polarized light, achieving orthogonal polarization conversion. In this process, the shape and arrangement of the elliptical silicon nanopillar array play a crucial role in the decomposition of light, the generation of phase difference, and the final polarization conversion. The core advantage of this orthogonal polarization conversion mechanism lies in its ability to not only efficiently convert polarized light but also to precisely control various parameters during the conversion process by designing silicon nanopillars of different sizes and arrangements. This design method can operate over a wide frequency range and is particularly suitable for optical devices requiring high-precision polarization control, such as polarization light sources, optical sensors, and polarization modulators. By optimizing the geometry and arrangement of the nanopillars, high polarization conversion performance can be maintained at different wavelengths and incident angles.

[0068] Polarization conversion efficiency (PCR) is the ratio of the energy required to achieve a polarization state transition to the total outgoing energy at a specific incident wavelength. In the case of a half-wave plate, PCR efficiency is defined as the ratio of the energy that causes a polarization state deflection of π to the total outgoing energy, where 100% conversion efficiency corresponds to a PCR value of 1. To more accurately describe polarization conversion efficiency, PCR can be quantitatively expressed as: PCR = |Rxy| 2 / (|Rxy| 2 +|Rxx| 2 Where Rxy and Rxx represent the reflection coefficients under different polarization states. Specifically, in this design, as shown... Figure 5 As shown, under X-ray polarization excitation, the PCR efficiency exhibits the best polarization conversion performance in the wavelength range of 1.53 μm to 1.66 μm, consistently remaining above 90%. This wavelength range includes the C+L communication band, demonstrating that the polarization converter can maintain high polarization conversion performance over a wider wavelength range. This range is highlighted in gray in the figure to further emphasize its excellent polarization conversion effect.

[0069] Figure 6 This figure illustrates the variation of phase difference and phase of polarized light with wavelength. The data in the figure are used to describe the effect of metasurfaces on the phase of light with different polarization states (polarized light along the x and y axes). The blue dashed line φ... x This represents the phase along the x-axis. As can be observed from the graph, with increasing wavelength λ, the phase change along the x-axis is relatively gradual, but the amplitude of the change is large. (Red dashed line φ)y The solid black line Δφ represents the phase along the y-axis. The phase difference is the difference between the phases of polarized light in two directions, used to describe the modulation effect of the waveplate on polarized light. The solid black line indicates that the 1.53µm to 1.66µm range is shaded, where the phase difference Δφ is approximately π, meaning that the phase difference within this range achieves the function of a half-wave plate.

[0070] like Figure 7 An orthogonal polarization converter can be composed of several regular hexagonal lattices. Figure 8 This is a top view of the corresponding orthogonal polarization converter. The elliptical dielectric nanopillars are made of silicon and are denoted as elliptical silicon nanopillars. The dielectric layer 20 is made of silicon dioxide and is denoted as the SiO2 dielectric layer. The metal reflective layer 30 can be made of gold, silver, aluminum, or copper. The thickness of the metal reflective layer 30 is 100~300nm, used to provide a high reflectivity substrate (>95%). The thickness of the SiO2 dielectric layer is 100~300nm, located above the metal reflective layer 30. An array of elliptical high refractive index dielectric nanopillars is periodically arranged on the upper surface of the SiO2 dielectric layer. Each nanopillar has an elliptical cross-section, with a height H=700~1000nm, a major axis length La=100~300nm, a minor axis length Lb=80~200nm, an axial ratio La / Lb=1.2:1~1.5:1, and the direction of the major axis forms an angle of 45°±5° with the X-polarization direction of the incident light. The array period P = 650 nm (satisfying the subwavelength condition P < λ).

[0071] Figure 9 This study demonstrates the effect of different reflective layer materials on the PCR efficiency of orthogonal polarization converters under X-ray polarization. Four metal materials—aluminum (Al), gold (Au), copper (Cu), and silver (Ag)—were used as the metal reflective layer 30, and their performance in PCR efficiency was tested. Figure 9 As can be clearly seen, regardless of the metal material used as the metal reflector layer 30, the PCR efficiency of the orthogonal polarization converter consistently reaches over 90% within the wavelength range of 1.53 μm to 1.66 μm, demonstrating the high efficiency and stability of this design. To further clarify the results, the area with efficiency above 90% is highlighted in gray and presented in a small plot, fully emphasizing the excellent performance and versatility of this orthogonal polarization converter with various reflector materials. This further proves the broad applicability and reliability of the device structure, enabling it to maintain high polarization conversion performance in different materials and application environments.

[0072] The above embodiments should not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent conversion fall within the protection scope of the present invention.

Claims

1. An orthogonal polarization converter based on a reflective dielectric metasurface, characterized in that, include: Dielectric metasurface functional layer, dielectric layer, metal reflective layer; The dielectric metasurface functional layer is disposed on the upper surface of the dielectric layer, and the metal reflective layer is disposed on the lower surface of the dielectric layer; The dielectric metasurface functional layer is composed of a periodically arranged array of elliptical dielectric nanopillars, which is used to control the polarization state of incident light based on Mie resonance. When X-polarized light enters the elliptical dielectric nanopillar array, the elliptical dielectric nanopillar array modulates the phase of the incoming X-polarized light based on Mie resonance, resulting in orthogonal Y-polarized light. The wavelength of the incident light is in the near-infrared band, and the wavelength is 1.53um to 1.66um; The elliptical dielectric nanopillar array is made of silicon; The dielectric layer is made of silicon dioxide; the thickness of the dielectric layer is 100–300 nm. The cross-section of the nanopillars in the elliptical dielectric nanopillar array is elliptical, and the height of the nanopillars is 700-1000 nm. The cross-section of the nanopillar has a major axis length of 100–300 nm and a minor axis length of 80–200 nm, with an axis ratio of 1.2:1 to 1.5:

1. The long axis of the cross-section of the nanopillar forms an angle of 45°±5° with the X-polarization direction of the incident light; The material of the metal reflective layer is aluminum; The metal reflective layer is an aluminum reflective layer with a thickness of 100–300 nm; The orthogonal polarization converter exhibits excellent polarization conversion performance in the wavelength range of 1.53 μm to 1.66 μm under X-polarized light excitation, with the efficiency consistently remaining above 90%.

2. The orthogonal polarization converter according to claim 1, characterized in that, The period of the elliptical dielectric nanopillar array is 650 nm.

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