High quality factor photonic spin hall effect modulation method and application

Abstract

The application discloses a high-quality-factor photonic spin Hall effect regulation method, comprising the following steps: S1, providing a metasurface for realizing PSHE enhancement, providing a structural basis and a physical platform for the whole regulation method, and being a prerequisite for realizing high-Q-factor PSHE; S2, exciting an optical field on the metasurface and utilizing the topological protection BIC existing at the Brillouin zone Gamma point of the metasurface, forming quasi-BIC resonance after introducing symmetry breaking, converting ideal BIC into a couplable resonance state, and providing a physical mechanism for PSHE enhancement; S3, under the resonance state excited in S2, realizing quantitative prediction and active regulation of PSHE displacement through theoretical modeling and numerical analysis, and verifying through experimental means. According to the application, by regulating an incident light wave vector, PSHE can be significantly enhanced with a Q factor of more than 1000 near the quasi-BIC resonance.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano optical field manipulation and sensing technology, specifically relating to a high-quality factor photonic spin Hall effect manipulation method and its application. Background Technology

[0002] The Photonic Spin Hall Effect (PSHE) refers to the phenomenon that when a spatially confined linearly polarized light field is reflected or refracted at an optical interface, its left-hand and right-hand circularly polarized components split in the transverse and in-plane directions.

[0003] This effect can be viewed as an optical analogue to the spin Hall effect in electronic systems, originating from the spin-orbit coupling of photons. PSHE not only provides a new means of manipulating light fields at the nanoscale, but also shows significant application potential in precision measurement, optical sensing, and spin optoelectronic devices. However, the extremely weak nature of PSHE under normal circumstances makes it difficult to observe directly, limiting its practical applications.

[0004] To enhance the interaction between light and matter (PSHE), previous studies have employed methods such as the Brewster effect, metasurfaces, and surface plasmon resonance to improve the light-matter interaction. Although these methods have achieved some success in experiments, their quality factors are generally low due to the wide resonance peak width and significant material loss, resulting in limited light field modulation efficiency and restricting the application of PSHE in high-performance optical devices.

[0005] In recent years, bound states in the continuous spectrum (BIC) have attracted widespread attention due to their unique advantages in realizing high-quality factor light-matter interactions. For example, see the paper A. Kodigala, T. Lepetit, Q. Gu, B. Bahari, Y. Fainman, and B. Kanté. Lasing action from photonic bound states in continuum. Nature, 541: 196-199 (2017).

[0006] This is a special spatially confined resonance state where energy is embedded in a continuous propagation mode spectrum. An ideal BIC has an infinite quality factor, but it cannot couple with incident light. By introducing symmetry-breaking perturbations, an ideal BIC can be transformed into a quasi-BIC, achieving a finite but high quality factor, and showing promising application prospects in laser emission, refractive index sensing, chirality detection, second harmonic generation, and imaging.

[0007] Previous studies have attempted to excite quasi-BIC in composite grating waveguides and enhance PSHE, such as the paper F. Wu, T. Liu, Y. Long, S. Xiao, and G. Chen. Giant photonic spin Hall effect empowered by polarization-dependent quasibound states in the continuum in compound grating waveguide structures. Phys. Rev. B 107: 165428 (2023).

[0008] However, the incident polarization state during PSHE enhancement is not the polarization state exhibited by the q-BIC effect. Therefore, the Q factor remains significantly lower than 100 during PSHE enhancement, and the PSHE splitting is limited to the lateral direction, resulting in limited in-plane control capability. Overall, there is still significant room for improvement in performance.

[0009] For PSHE sensors and spin photonic devices that require high sensitivity and multidimensional manipulation, there is an urgent need for a technical solution that can simultaneously achieve a high quality factor, possess efficient lateral and in-plane displacement control capabilities, and have a simple structure that is easy to integrate. Therefore, how to achieve a quality factor significantly higher than the existing level in a simple on-chip structure, while simultaneously enabling multidimensional enhanced control of PSHE, has become a critical technical challenge that needs to be overcome in this field. Summary of the Invention

[0010] To overcome the shortcomings of the existing technology, the present invention aims to provide a method and application for high-quality factor photonic spin Hall effect modulation. This involves designing a silicon nanopillar array metasurface with a periodic tetragonal lattice arrangement on a fused silica substrate. The topologically protected BIC (Bipolar Induction Center) at the Γ point in the Brillouin zone of this metasurface is excited and utilized, forming a quasi-BIC resonance after symmetry breaking. Around this resonance point, a large wave vector-dependent Pancharatnam-Berry (PB) phase gradient and a resonant reflection phase gradient are generated in momentum space, which are used to enhance the transverse and in-plane spin-dependent shifts of the photonic spin Hall effect (PSHE), respectively. By modulating the incident light wave vector, a significant enhancement of the PSHE with a Q factor exceeding 1000 can be achieved near this quasi-BIC resonance.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for controlling the high-quality factor photonic spin Hall effect includes the following steps; S1. Provide a metasurface for achieving PSHE enhancement, which provides the structural basis and physical platform for the entire control method and is a prerequisite for achieving high Q factor PSHE. S2. By exciting the BIC with an optical field on the metasurface and utilizing the topologically protected BIC at the Γ point in the Brillouin zone of the metasurface, a quasi-BIC resonance is formed after symmetry breaking is introduced, transforming the ideal BIC into a couplerable resonance state, providing a physical mechanism for PSHE enhancement. S3. Under the resonance state excited by S2, the quantitative prediction and active control of the PSHE displacement are realized through theoretical modeling and numerical analysis, and verified by experimental means.

[0012] In S1: The metasurface comprises a fused silica substrate and an array of silicon nanopillars arranged in a square lattice on the fused silica substrate, wherein the center points of all silicon nanopillars are located on equally spaced grid nodes, the center-to-center distance between adjacent nanopillars is equal, and the array size is [missing information]. .

[0013] Furthermore, the structure of each silicon nanopillar has Symmetry, meaning that its cross-sectional shape can perfectly coincide with itself after rotating 90 degrees around the central axis, has the following structural parameters: lattice constant. a = 440nm~445nm, diameter of nanopillars d =210nm~215nm, height h = 325nm~330nm.

[0014] Furthermore, the silicon nanopillar structure is fabricated using standard semiconductor micro / nano fabrication processes, specifically including the following steps: First, on a cleaned fused silica substrate, an amorphous silicon thin film of the required thickness is deposited using plasma-enhanced chemical vapor deposition or electron beam evaporation. Subsequently, electron beam photoresist is coated on the surface of the amorphous silicon thin film, and the designed nanopillar array pattern is precisely exposed using electron beam photolithography. After development, an etching mask is formed. Next, using the photoresist pattern as a mask, inductively coupled plasma etching (ICP-ED) technology is employed to transfer the pattern with high fidelity onto the underlying amorphous silicon thin film, forming a film with... Symmetrical silicon nanopillars; Finally, the residual photoresist is removed by a photoresist stripping process, and the sample is cleaned and dried as necessary to obtain the final metasurface device.

[0015] Specifically, S2 is: A linearly polarized Gaussian beam with a candidate frequency range of 527 THz to 532 THz is incident on the metasurface at an angle of 4 to 8 degrees, wherein the angular spectrum distribution of the Gaussian beam is as follows: (1) In-plane wave vector , and These are the incident wave vectors k of x and y Directional components; Let be the waist radius of the Gaussian beam.

[0016] The oblique incident angle disrupts the in-plane rotational symmetry, transforming the ideal BIC into a couplerable quasi-BIC resonance state; wherein the frequency of the Gaussian beam is adjustable within a candidate range containing the quasi-BIC resonance peak, the candidate range being 527THz~532THz.

[0017] Furthermore, the metasurface is subjected to reflectance spectroscopy testing to obtain the optimal operating frequency. f； First, the metasurface sample to be tested is placed on a two-dimensional precision displacement platform, and incident light is irradiated onto the metasurface at an angle of 4 to 8 degrees. Then, the incident light frequency was scanned between 527 THz and 532 THz, and the reflected signals at different frequencies were recorded to obtain the frequency domain reflection spectrum; the frequency at the midpoint of the peak and trough of the Fano resonance curve of the reflection spectrum was selected as the optimal operating frequency. f And at that frequency, quasi-BIC resonance is excited.

[0018] Specifically, S3 is: Based on the determined incident light frequency that excites quasi-BIC resonance f Then, according to the time-domain coupled-mode theory, the in-plane wave vector Under incident conditions, the resonant reflection process of the metasurface is described in momentum space by the following formula. (2) in and These are the Jones matrices of the incident and reflected light fields, respectively. and These are the common and cross circular polarization reflection coefficients, respectively. Represents the polarization state of the radiation mode Azimuth angle; phase factor This is called the PB phase; for a polarization angle of 100°... Given an incident light field, the reflection phases of left-handed (LCP, +) and right-handed (RCP, -) circularly polarized light are: (3) PB phase in momentum space The gradient of the direction and the reflection phase are in The gradient in direction will cause displacement of the light in the plane of real space and the horizontally circularly polarized plane, respectively; (4) For a linearly polarized fundamental Gaussian beam in S2, the transverse displacement of its PSHE relative to the in-plane LCP and RCP is expressed as: (5) (6) in (7) Furthermore, to ensure computational accuracy, a first-order Taylor expansion of the reflection coefficient is required during the calculation process. .

[0019] Calculation of energy stored in a single nanopillar using the finite element method U With outward radiated power P The Q factor is expressed as (8) Using the above formulas (4) and (5), calculate the different incident wave vectors one by one. The transverse and in-plane PSHE displacements at different incident angles, i.e. and ; When the incident wave vector Approaching the quasi-BIC resonance point At that time, the reflected phase gradient Take the maximum value, in-plane displacement Significant enhancement is achieved when the incident wave vector Deviation from resonance point to a specific value At that time, the lateral displacement is at the PB phase gradient Inducement, in The lateral displacement first decreases and then increases within a certain range; this phenomenon originates from... The sharp increase near the resonance point weakens the PSHE; by adjusting the incident wave vector... Set within a specific interval near the resonance point, for example This allows for high levels of both in-plane and lateral displacement, achieving synergistic enhancement of both. Therefore, by scanning the incident wave vector... (That is, by changing the incident angle), one can selectively enhance in-plane displacement or lateral displacement, or in a specific... Significant enhancements of both can be achieved simultaneously within the range, thereby enabling flexible control of PSHE.

[0020] Furthermore, the PSHE measurement system used to realize the high-quality factor photonic spin Hall effect modulation method verifies the predicted PSHE shift: A Gaussian beam of a specific frequency output from a laser is passed through a half-wave plate, a lens, and a polarizer before being incident on the surface of the metasurface sample. The polarization degree is adjusted by the half-wave plate and the polarizer, and the lens is used to narrow the beam to make the PSHE effect more obvious. The orientation of the metasurface sample needs to be precisely adjusted to align its crystal axis with the measurement coordinate system; After being reflected by the metasurface sample, the reflected beam is received by a high-precision CCD camera after passing through a quarter-wave plate and a polarizer II. By adjusting the fast axis angle of the quarter-wave plate and polarizer two, the left and right circularly polarized components in the reflected beam are extracted based on Stokes parameter analysis. and ; The actual PSHE displacement is then calculated using the following formula: (9) (10) By comparing the reference position of the incident light spot, the absolute displacement of the LCP and RCP components in the in-plane and lateral directions can be directly obtained; the incident angle can be changed by scanning. This allows for the systematic measurement of displacement. and The relationship between the variation of wave vector and the theoretical prediction value. and Comparative verification was conducted.

[0021] The high-quality factor photonic spin Hall effect modulation method described above is applied to high-sensitivity structural defect detection. PSHE in the quasi-BIC state is particularly sensitive to small changes in system parameters, and therefore can be used in the detection of defects in metasurface manufacturing. Different nanopillar diameters d and height h The following calculations are performed to determine the total spin splitting distance of the PSHE beam: ; in and These represent the theoretically predicted in-plane and lateral displacements of PSHE, respectively.

[0022] Establish "structural parameters" d ( h - Split distance SThe calibration curve was then obtained. The fabricated metasurface sample was then placed in the PSHE measurement system mentioned in S3, the spot size was measured, and the actual total spin splitting distance of the beam PSHE was calculated using formulas (9) and (10). ,Will Compared with the pre-established calibration curve Compare the data using the calibration curves. S With the diameter of the nanopillar h and height d The one-to-one correspondence can be used to quantitatively determine the deviation of the sample in height or diameter relative to the standard design, thus achieving non-contact, high-resolution detection of structural defects.

[0023] The beneficial effects of this invention are: This invention enables the excitation of quasi-BICs on a simple silicon nanopillar metasurface platform to induce a wave vector-dependent giant Pancharatnam-Berry (PB) phase gradient and resonant reflection phase gradient in momentum space, achieving PSHE enhancement with a quality factor exceeding 1000. This is more than an order of magnitude higher than existing methods, greatly enhancing the efficiency of light-matter interaction. Meanwhile, this method can synergistically control in-plane and lateral spin-dependent displacements, breaking through the limitations of single-dimensional control. The sensor built based on this effect is extremely sensitive to changes in structural parameters and can achieve deep sub-nanometer level defect detection. Its spatial resolution is up to 20 times higher than that of traditional optical microscopy methods, and the overall structure is compatible with semiconductor processes, making it easy to integrate and apply on-chip. Attached Figure Description

[0024] Figure 1 (a) is a schematic diagram of the metasurface in Embodiment 1 of the present invention. Figure 1 (b) The difference in quality factor between quasi-BIC and ordinary Fano resonance. Figure 1 (c) is a schematic diagram of the longitudinal component of the magnetic field in the quasi-BIC state, where the arrows represent the transverse vector of the electric field. Figure 1 (d) represents the far-field BIC polarization vortex of metasurface radiation.

[0025] Figure 2 This is the momentum space phase gradient distribution of Embodiment 1 of the present invention; (a) is the PB phase in The gradient of the direction, (b) is the reflection phase at... f = 530.3THz Orientation gradient.

[0026] Figure 3 The PSHE performance of Embodiment 1 of the present invention is shown in (a) as in-plane and transverse photon spin splitting, and (b) as total spin splitting shift and quality factor.

[0027] Figure 4 The PSHE measurement system used in Embodiments 1 and 2 of the present invention is shown.

[0028] Figure 5 The sensor performance of Embodiment 2 of the present invention is shown, namely the total spin splitting displacement as a function of (a) the height and (b) the diameter of the silicon cylinder. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings.

[0030] Example 1: Implementation of a high-quality factor PSHE regulation method based on quasi-BIC. This example details how to achieve the aforementioned high-quality factor PSHE regulation.

[0031] S1, Metasurface Structure Provides: A metasurface for achieving PSHE enhancement is provided, such as Figure 1 As shown in (a), the metasurface comprises a fused silica substrate and an array of silicon nanopillars arranged in a periodic tetrahedral lattice on the substrate, wherein the center points of all silicon nanopillars are located on equally spaced grid nodes, and the center-to-center distance between adjacent nanopillars is equal. Each silicon nanopillar has a structure with... Symmetry, meaning that its cross-sectional shape can perfectly coincide with itself after rotating 90 degrees around its central axis. A preferred set of structural parameters are as follows: lattice constant. a = 442nm, diameter of nanopillar d = 212nm, height h = 328nm. This structure can be fabricated using standard semiconductor micro / nano fabrication processes. First, utilizing the high precision of electron beam lithography, a structure with... Symmetrical nanopillar patterns are formed; then, through inductively coupled plasma etching technology, the anisotropic etching characteristics are utilized to achieve vertical transfer of the patterns, thereby completing the fabrication of silicon nanopillar arrays.

[0032] S2, the incident light field excites quasi-BIC resonance: Preferably, a linearly polarized beam with an angle of... ,frequency f =530.3THz, waist radius A Gaussian beam with an angular spectral distribution satisfying formula (1) is incident on the metasurface at an angle of 6 degrees, and the excited topologically protected BIC is generated by... Figure 1 (c) shows the dominance of electric quadrupole moment resonance. In momentum space... Within the range, the polarization state of the radiation mode The quality factor and the quality factor under ordinary Fano resonance, for example Figure 1As shown in (b), the Q-factor in this method is improved by more than 10-fold under near-normal incidence. Furthermore, the polarization state of the radiation mode... Azimuth Distribution as Figure 1 As shown in (d), it can be seen that the topology-protected BIC has a polarization topological vortex at the Γ point in the Brillouin zone. Near this vortex, the azimuth angle... The changes were so dramatic that they provided an opportunity to induce huge spin-orbit interactions.

[0033] Calculation and regulation of S3, PSHE and Q factors: The phase of PB in momentum space can be calculated using formula (4). The gradient of the direction and the reflection phase are in Gradient of direction, such as Figure 2 As shown. The large PB phase gradient and reflected phase gradient near the resonance point lead to transverse and in-plane PSHE in real space, respectively, which is the intrinsic physical mechanism of PSHE enhancement. Then, different incident wave vectors can be calculated using equations (5) and (6). In the PSHE plane and lateral displacement and like Figure 3 As shown in (a).

[0034] Specifically, when the incident wave vector When approaching the resonance point ( The LCP and RCP components in the reflected beam are in-plane ( x A significant reverse displacement occurs in the axial direction, reaching its maximum value near the resonance point, for example, up to 14.3. λ Furthermore, the PB phase gradient causes the LCP and RCP components to diverge in the lateral direction ( y Significant reverse displacement also occurs in the axial direction. It is worth noting that, in... As the lateral displacement sweeps across the resonance point, it exhibits a trend of first decreasing and then increasing, varying at specific points away from the resonance point. Larger values, such as 6.2, can also be obtained below. λ This phenomenon originates from The sharp increase near the resonance point weakens the PSHE. Meanwhile, different incident wave vectors can be calculated using formula (7). The Q factor at the location, such as Figure 3 As shown in (b), it can be observed that the total spin splitting distance of the PSHE... Greater than 5 λ At that time, the Q factor was greater than 1000. High Q factor PSHE enhancement was successfully achieved. The regulatory effect can be verified by experimental measurement using the PSHE measurement system described in section S3 of the invention. The specific structure is as follows: Figure 4 As shown: A Gaussian beam of a specific frequency output from a laser is passed through a half-wave plate, a lens, and a polarizer before being incident on the surface of the metasurface sample. The polarization degree is adjusted by the half-wave plate and the polarizer, and the lens is used to narrow the beam to make the PSHE effect more obvious. The orientation of the metasurface sample needs to be precisely adjusted to align its crystal axis with the measurement coordinate system; After being reflected by the metasurface sample, the reflected beam is received by a high-precision CCD camera after passing through a quarter-wave plate and a polarizer II. By adjusting the fast axis angle of the quarter-wave plate and polarizer two, the left and right circularly polarized components in the reflected beam are extracted based on Stokes parameter analysis. and ; The actual PSHE displacement is then calculated using the following formula: (9) (10) By comparing the reference position of the incident light spot, the absolute displacement of the LCP and RCP components in the in-plane and lateral directions can be directly obtained; the incident angle can be changed by scanning. This allows for the systematic measurement of displacement. and The relationship between the variation of wave vector and the theoretical prediction value. and Comparative verification was conducted.

[0035] In this process, polarizer one and polarizer two are both set to 45 degrees, and then the fast axis of the quarter-wave plate is set to 90 degrees and 0 degrees respectively to extract the left and right circularly polarized light components.

[0036] Example 2: Implementation of a metasurface structure defect sensing method based on the PSHE effect: This embodiment is based on the metasurface and control method provided in Embodiment 1 above, and illustrates how to apply it to high-sensitivity structural defect detection.

[0037] Manufacturing defect detection based on high Q factor PSHE: Figure 5 Frequency was displayed f = 530.3 THz (corresponding wavelength) λ= 565.7nm), polarization angle , the incident wave vector When a Gaussian beam of light is incident on a standard defect-free metasurface sample, the total spin splitting distance of the PSHE is: ; With the diameter of nanopillars d and height h The changing trend.

[0038] It can be observed that, S Regarding the diameter of nanopillars h and height d The changes are extremely sensitive and highly linear, with sensitivities reaching 207. λ / nm and 998 λ / nm, even h and d Changes of 0.01 nm and 0.002 nm at the deep sub-nanometer level, respectively, will also lead to... S Significant changes in wavelength occur, allowing for high-precision detection.

[0039] Therefore, the processed metasurface sample to be tested is placed in the PSHE measurement system mentioned in S3 (such as...). Figure 4 As shown), the spot size was measured and the actual total spin splitting distance of the beam PSHE was calculated using formulas (9) and (10); ; Will Compared with the pre-established calibration curve Compare the data using the calibration curves. S With the diameter of the nanopillar h and height d The one-to-one correspondence allows for the quantitative determination of the deviation of the sample from the standard design in height or diameter, enabling non-contact, high-resolution detection of structural defects. Its spatial resolution is up to 20 times higher than that of the traditional trans-focused scanning optical microscopy (TSOM) method.

Claims

1. A method for controlling the high-quality factor photonic spin Hall effect, characterized in that, Includes the following steps; S1. Provide a metasurface for achieving PSHE enhancement; S2. By exciting the BIC with an optical field on the metasurface and utilizing the topologically protected BIC that exists at the Γ point in the Brillouin zone of the metasurface, a quasi-BIC resonance is formed after the introduction of symmetry breaking, transforming the ideal BIC into a coupletable resonance state, and providing a physical mechanism for PSHE enhancement. S3. Under the resonance state excited by S2, the quantitative prediction and active control of the PSHE displacement are realized through theoretical modeling and numerical analysis.

2. The method for controlling the high-quality factor photonic spin Hall effect according to claim 1, characterized in that, In S1: The metasurface comprises a fused silica substrate and an array of silicon nanopillars arranged periodically in a square lattice on the fused silica substrate, wherein the center points of all silicon nanopillars are located on equally spaced grid nodes, the center-to-center distance between adjacent nanopillars is equal, and the array size is [missing information]. .

3. The method for controlling the high-quality factor photonic spin Hall effect according to claim 2, characterized in that, Each silicon nanopillar has a structure with Symmetry, meaning that its cross-sectional shape can perfectly coincide with itself after rotating 90 degrees around the central axis, has the following structural parameters: lattice constant. a = 440nm~445nm, diameter of nanopillars d = 210nm~215nm, height h =325nm~330nm.

4. The method for controlling the high-quality factor photonic spin Hall effect according to claim 3, characterized in that, The silicon nanopillars are fabricated using standard semiconductor micro / nano fabrication processes, specifically including the following steps: First, an amorphous silicon thin film is deposited on a cleaned fused silica substrate using plasma-enhanced chemical vapor deposition or electron beam evaporation. Subsequently, electron beam photoresist is coated on the surface of the amorphous silicon thin film, and the designed nanopillar array pattern is precisely exposed using electron beam photolithography. After development, an etching mask is formed. Next, inductively coupled plasma etching (ICP-ED) is used to transfer the pattern onto the underlying amorphous silicon thin film, forming a structure with... Symmetrical silicon nanopillars; Finally, the residual photoresist is removed by a photoresist stripping process, and the sample is cleaned and dried as necessary to obtain the final metasurface device.

5. The method for controlling the high-quality factor photonic spin Hall effect according to claim 1, characterized in that, Specifically, S2 is: The silicon nanopillars in the metasurface have The symmetry and periodic arrangement of the tetragonal lattice enable the metasurface to support topologically protected bound states (BICs) in the continuous spectrum at the Γ point in the Brillouin zone. When a linearly polarized Gaussian beam of fundamental mode is incident on the metasurface at an angle of 4–8 degrees, the angular spectrum distribution of the Gaussian beam is as follows: (1) In-plane wave vector , and These are the incident wave vectors k of x and y Directional components; Let be the waist radius of the Gaussian beam; The oblique incident angle disrupts the in-plane rotational symmetry, transforming the ideal BIC into a couplerable quasi-BIC resonance state; the frequency of the Gaussian beam is tunable within a candidate range containing the quasi-BIC resonance peak, which is 527 THz to 532 THz.

6. The method for controlling the high-quality factor photonic spin Hall effect according to claim 5, characterized in that, The metasurface was subjected to reflectance spectroscopy testing to obtain the optimal operating frequency. f ; First, the metasurface sample to be tested is placed on a two-dimensional precision displacement platform, and incident light is irradiated onto the metasurface at an angle of 4–8 degrees. Then, the incident light frequency is scanned between 527 THz and 532 THz, and the reflection signals at different frequencies are recorded to obtain the frequency domain reflection spectrum. The frequency at the midpoint of the peak and trough of the Fano resonance curve of the reflection spectrum is selected as the optimal working frequency. f And at that frequency, quasi-BIC resonance is excited.

7. The method for controlling the high-quality factor photonic spin Hall effect according to claim 6, characterized in that, Specifically, S3 is: Based on the determined incident light frequency that excites quasi-BIC resonance f Then, according to the time-domain coupled-mode theory, the in-plane wave vector Under incident conditions, the resonant reflection process of the metasurface is described in momentum space by the following formula: (2) in and These are the Jones matrices of the incident and reflected light fields, respectively. and These are the common and cross circular polarization reflection coefficients, respectively. Represents the polarization state of the radiation mode Azimuth angle; phase factor This is called the PB phase; for a polarization angle of 100°... The incident light field, the reflection phases of left-handed (LCP, symbol +) and right-handed (RCP, symbol -) circularly polarized light are: (3) PB phase in momentum space The gradient of the direction and the reflection phase are in The gradient in direction will cause displacement of the light in the plane of real space and the horizontally circularly polarized plane, respectively; (4) For a linearly polarized fundamental Gaussian beam in S2, the transverse displacement of its PSHE relative to the in-plane LCP and RCP is expressed as: (5) (6) in (7) Furthermore, to ensure computational accuracy, a first-order Taylor expansion of the reflection coefficient is required during the calculation process. . Calculation of energy stored in a single nanopillar using the finite element method U With outward radiated power P The Q factor is expressed as (8) Using the above formulas (4) and (5), calculate the different incident wave vectors one by one. The horizontal and in-plane PSHE displacements below, i.e. and The regulatory pattern is as follows: When the incident wave vector Approaching the quasi-BIC resonance point At that time, i.e., the reflection phase gradient At the point of maximum value, the in-plane displacement Significant enhancement is achieved; the left- and right-handed circularly polarized light undergoes reverse splitting in the in-plane direction, reaching its maximum near the resonance point; the lateral displacement is determined by the PB phase gradient. Inducement, in Within a certain range, the lateral displacement first decreases and then increases, by scanning the incident wave vector. This allows for the selective enhancement of in-plane or lateral displacement, or in specific... Significant enhancements of both can be achieved simultaneously within the range, enabling flexible control of PSHE.

8. The high-quality factor photonic spin Hall effect modulation method according to claim 7 is characterized in that, Set up a PSHE measurement system to verify the predicted PSHE displacement: A Gaussian beam of a specific frequency output from a laser is passed through a half-wave plate, a lens, and a polarizer before being incident on the surface of the metasurface sample. The polarization degree is adjusted using the half-wave plate and the polarizer. The orientation of the metasurface sample needs to be precisely adjusted to align its crystal axis with the measurement coordinate system; After being reflected by the metasurface sample, the reflected beam is received by a high-precision CCD camera after passing through a quarter-wave plate and a polarizer II. By adjusting the fast axis angle of the quarter-wave plate and polarizer two, the left and right circularly polarized components in the reflected beam are extracted based on Stokes parameter analysis. and ; The actual PSHE displacement is then calculated using the following formula: (9) (10) By comparing the reference position of the incident light spot, the absolute displacement of the LCP and RCP components in the in-plane and lateral directions can be directly obtained; the incident angle can be changed by scanning. This allows for the systematic measurement of displacement. and The relationship between the variation of wave vector and the theoretical prediction value. and Comparative verification was conducted.

9. The application of the high-quality factor photon spin Hall effect modulation method according to claim 8, characterized in that, The method is applied to high-sensitivity structural defect detection; Different nanopillar diameters d and height h The following calculations are performed to determine the total spin splitting distance of the PSHE beam: ； in and These represent the theoretically predicted in-plane and lateral displacements of PSHE, respectively. Establish structural parameters d ( h - Split distance S The calibration curve was obtained, and then the processed metasurface sample to be tested was placed in the PSHE measurement system to measure the spot and calculate the actual total spin splitting distance of the beam PSHE using formulas (9) and (10). ； Will Compared with the pre-established calibration curve Compare the data using the calibration curves. S With the diameter of the nanopillar h and height d The one-to-one correspondence can be used to quantitatively determine the deviation of the sample in height or diameter relative to the standard design, thus achieving non-contact, high-resolution detection of structural defects.

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