All-dielectric adjustable optical tweezers based on composite phase super lens

Abstract

The invention relates to full-dielectric adjustable optical tweezers based on a composite phase superlens, and belongs to the technical field of optical tweezers. Two regulation modes of geometric phase and transmission phase are integrated into a dielectric metasurface periodic structure, and a circular lens surface is combined according to a specific mapping and arrangement mode. The super lens can excite two different output electric fields under the input of linearly polarized light due to the regulation and control of a composite phase, and the two electric fields can independently exist under the input of circularly polarized light with opposite chirality. Therefore, by adjusting the polarization type of the incident light source of the super lens, free switching of multiple optical capturing modes of particles in a field can be realized. Compared with the existing optical tweezers, the control mode can be flexibly adjusted on the premise that the structure of the device is not changed, and more diversified particle capturing requirements can be met. The high-flexibility and easy-to-integrate micro-nano structure can provide powerful guarantee for the performance of a compact composite optical capturing device.

Description

TECHNICAL FIELD

[0001] The present application relates to a full-dielectric adjustable optical tweezers based on composite phase superlens, which can switch different optical trapping modes by adjusting the polarization state of the incident light source, and can stably capture nanoparticles in various ways. It belongs to the technical field of optical tweezers. BACKGROUND

[0002] Since a series of pioneering studies on optical manipulation of biological macromolecules using light beams in free space in the 1980s (Document 1: Ashkin A, Dziedzic JM, Bjorkholm JE, Chu S. Observation of a single-beam gradient force optical trap for dielectric particles. Opt Lett 1986, 11: 288-290.), optical tweezers technology has gradually developed to the level of nanoscale precision in the manipulation of particles on the subwavelength scale, and various types of optical tweezers have been widely used in the capture and manipulation of proteins, DNA, cells and viruses, and have important application prospects in frontier fields such as molecular biology and biological medicine.

[0003] Metalens is a special metasurface structure with optical focusing function, which is composed of a spatially periodic array of subwavelength structures. When a light source is incident on the surface of the metalens, each nanometer structure unit undergoes light-matter interaction, which collectively modulates the phase of the incident light, thereby producing a highly localized focused light field. The commonly used phase control methods are transmission phase and geometric phase methods. Based on these methods, metalenses have been successfully prepared and have realized important functions such as high magnification optical amplification and chiral optical imaging of visible light wavelengths (Literature 2: Achromatic Metalens over 60nm Bandwidth in the Visible and Metalens with Reverse Chromatic Dispersion M. Khorasaninejad, Z. Shi, A. Y. Zhu, W. T. Chen, V. Sanjeev, A. Zaidi, and F. Capasso Nano Letters 2017 17(3), 1819-1824.). As a new optical element, the flexibility, compactness and easy integration of metalens have attracted more in-depth research in the field of optical and photonic applications, and have made gratifying progress in quantum optics, cold atom generation and capture, etc. (Literature 3: Lingxiao Zhu et al., A dielectric metasurface optical chip for the generation of cold atoms. Sci. Adv. 6, eabb6667 (2020)).

[0004] As mentioned earlier, metalens can produce a highly localized focused light field, which can form a three-dimensional optical trap with a change in the amplitude of the evanescent wave at the edge, and the particle is tightly confined in the center of the trap by the field gradient. Preliminary exploration and verification of contactless optical trapping in the far field using metalens have been carried out (Literature 4: T. Chantakit, et al., "All-dielectric silicon metalens for two-dimensional particle manipulation in optical tweezers," Photon. Res. 8, 1435-1440 (2020).), and the integration of metalens and optical tweezers technology is an important supplement and innovation to the field of optical tweezers research. However, most existing optical tweezers based on metalens have only a single trapping mode, cannot quickly switch the manipulation mode of the particle, or the adjustment cost is too high, and cannot adapt to flexible and diverse optical trapping requirements.

[0005] Therefore, the application combines two phase control modes (transmission phase and geometric phase) of the superlens, so that two different output electric fields can be excited under a linearly polarized light source. The two fields can exist independently and do not interfere with each other under circularly polarized light input with opposite chirality, and correspond to two independent optical trapping modes. The optical tweezers based on the superlens can flexibly adjust the manipulation state of the nanoparticles by simply changing the polarization state of the incident light, without changing the structure, greatly reducing the adjustment cost, and widening the application range of the optical tweezers. SUMMARY

[0006] The application combines transmission phase and geometric phase into a superlens structure, realizes a full-dielectric optical tweezers that can be flexibly adjusted by the polarization state of the incident light, and can realize multiple optical trapping modes without changing the structure, improving the flexibility and diversity of optical manipulation of particles.

[0007] 1. Specific content of the application

[0008] (1) The optical tweezers structure proposed by the application is shown in Figure 1 The superlens surface is composed of unit cells with rectangular silicon nanocolumns as the main body arranged outward in a concentric circle model. The cell period is constant, and all the nanocolumns are of the same height. The length and width of the nanocolumns have 12 different combinations, and each nanocolumn has a specific horizontal rotation angle, which is related to the spatial position coordinates of the nanocolumn on the circular surface. In addition, in order to determine the specific geometric parameters (length, width and rotation angle) of the nanocolumn at each coordinate, first set the topological charge m = 3, the left-handed optical focal length f1 = 5 μm, the right-handed optical focal length f2 = 8 μm, and the total lens radius is 10 μm. According to the above parameters, the surface of the whole lens is built, and the surface is placed on a SiO2 substrate with a certain thickness. A linearly polarized light with a wavelength of 850 nm is input from the substrate side from bottom to top, and two different output electric field distributions can be observed on the focal planes corresponding to f1

[0009] and f2.

[0010] (2) Adjust the incident light to left-handed or right-handed polarization state, and the output electric field changes, as shown in Figure 2 For example, when the input is left-handed polarization, the optical focusing mode on the focal plane corresponding to the focal length f2 disappears completely, which is manifested as no local electric field distribution, while the original focusing light field on the focal plane corresponding to the focal length f1 still exists, and the central electric field amplitude is higher than that when the linearly polarized light is input. The right-handed polarization input is similar, and the output is only the vortex electric field on the focal plane corresponding to f2.

[0011] (3) For the optical tweezers proposed in the application, the particle manipulation mode and the trapping performance of the optical tweezers under left-handed and right-handed circularly polarized light input are considered respectively. The selected particle is a polystyrene spherical particle with a radius of 150 nm, which is placed from far to near in the focal plane where there is a clear electric field distribution, the two-dimensional optical force and optical torque of the particle along the position distribution in the radial direction are calculated, the motion state of the particle in the plane is derived from the change trend of the optical force, the optical trap position is obtained and the potential well depth is calculated, so as to reflect that the optical tweezers has a dynamic adjustable particle manipulation mode, and the high performance requirement of stable trapping in each mode is achieved.

[0012] 2. The advantages of the application are as follows:

[0013] (1) The application is an optical tweezers for far-field trapping of nanoparticles by using circularly polarized light and superlens structure. Since the optical trap is far away from the structure, the trapped particles will not affect the optical performance of the structure itself, greatly improving the robustness of the optical tweezers, which is suitable for repeated use.

[0014] (2) The application can excite two types of spatial topologically different optical fields under the incident light polarization with opposite chirality by the regulation of the complex phase, which corresponds to two different optical trapping modes respectively. Therefore, by simply adjusting the polarization state of the incident light source, the optical trapping modes can be quickly switched, that is, the motion state of the trapped particles can be flexibly changed, which can adapt to more diverse particle trapping requirements.

[0015] (3) In the focusing mode, the central potential well depth can reach 193.7k B T, in the vortex mode, the potential well depth in the ring can reach 127.6k B T, and the maximum torque is 1.74×10 -10 m 2 / s, which can ensure that the optical tweezers can stably drive and trap polystyrene particles in both trapping modes.

[0016] 3. The principle of the application is as follows:

[0017] (1) The core idea of the application is to superimpose the transmission phase and the geometric phase in the same high refractive index medium structure, so that the orthogonal polarization states can produce two independent optical responses respectively. Therefore, the incident of circularly polarized light with opposite chirality independently controls the two wavefront phases φ + (x,y) and φ - (x,y), and realizes the switching of different optical manipulation modes.

[0018] (2) In order to realize independent regulation of the phase, the phase shift φ x on the orthogonal polarization basis dominated by the transmission phase and φ yand the geometric phase dominated rotation angle θ, which is derived as follows:

[0019] The transmission phase β refers to the phase regulation by the optical path difference produced when the electromagnetic wave passes through the medium with different refractive indexes, which is defined as:

[0020]

[0021] where λ is the incident wavelength, n eff is the effective mode refractive index of the medium, and h is the height of the nanorod.

[0022] The necessary condition for the generation of geometric phase is that the unit structure has anisotropy, such as a rectangular nanorod with different length and width, and its generation mechanism can be explained by the Jones matrix J(x, y) (Ref. 5: ZHANG Fei, CAI Ji-Xiang, PUMing-Bo, LUO Xian-Gang. Composite-phase manipulation in optical metasurfaces[J]. PHYSICS, 2021, 50(5): 300-307.):

[0023]

[0024] where, is the rotation matrix, and are the complex amplitudes on two orthogonal bases, denoted by A u and A v . Substituting equation (2) gives:

[0025]

[0026] The incident circularly polarized light can be represented as (σ = ±1, representing two circular polarization chiralities), and according to the Jones matrix, the matrix representation of the output light field can be obtained as:

[0027]

[0028] E xo and E yo represent the polarization components in the orthogonal directions of the light field. We are interested in the component opposite to the incident circularly polarized light in chirality, i.e., the second term of equation (4), which can be found to have an additional phase of δ = -2σθ. This phase is the geometric phase, and when the incident is left-handed (σ = -1), the geometric phase δ = 2θ.

[0029] Next, we explain how the two phases are combined in the same nanorod structure. Let the structure amplitude be 1, and introduce a complex phase shift in the two orthogonal bases, i.e., the corresponding complex amplitudes When circularly polarized light is incident, substituting into equation (4) and simplifying it, we can obtain the matrix of the output light field at this time:

[0030]

[0031] From the second term on the right side of Equation (5), it can be seen that the component orthogonal to the polarization of the incident light is added with an additional phase of -2σθ+β, which is equal to the superposition of the transmission phase and the geometric phase, that is, the composite phase.

[0032] When two circularly polarized lights are incident simultaneously, the Jones matrix can be used to derive the transmission phase shift and rotation angle conditions required to independently control the phases of the two wavefronts, LCP (left-hand circularly polarized) and RCP (right-hand circularly polarized). The spatially varying Jones matrix can be written as (Reference 6: T. Li, et al., "Integrating the optical tweezers and spanner onto an individual single-layer metasurface," Photon. Res. 9, 1062-1068 (2021))

[0033]

[0034] in, Denote the left-handed and right-handed polarization directions respectively. Substituting equation (7) into equation (6), and simplifying, we obtain:

[0035]

[0036] By solving the characteristic equation of the matrix, we can obtain the eigenvalue and eigenvector of J(x,y), and diagonalize it similarly to J(x,y)=PΛP -1 , Λ is a diagonal matrix, P is a reversible matrix, expressed as a form that realizes two independent optical responses:

[0037]

[0038] Comparing Equation (9) with Equation (2), P can be regarded as the rotation matrix of Λ, from which the phase shift φ on two orthogonal bases can be obtained x ,φ y And the rotation angle θ satisfies the expression:

[0039]

[0040] The appropriate size of silicon rectangular columns and the additional rotation angle in each plane coordinate unit cell can be determined by formula (10).

[0041] In summary, the wavefront phase distribution determined by the orthogonal polarization basis can be superimposed in the same rectangular nanostructure, by allowing different phase distributions for orthogonal polarization states at the same time, two kinds of optical responses can be realized at the same time, and the two kinds of optical responses are independently controlled by LCP and RCP light input, so as to realize polarization switching optical trapping.

[0042] (3) The two kinds of optical responses correspond to the output electric field of two modes respectively, and the polystyrene particles are subjected to the gradient force in the field, so that they are captured in the light trap at a specific position. In particular, when the electric field distribution is annular, the particles will also obtain orbital angular momentum in the optical vortex, so that rotation along the ring can occur, and the rotation characteristics are expressed by the torque. The motion state of the particles in different trapping modes can be characterized by calculating physical quantities such as optical force and torque. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 (a) is a full structure model diagram of a composite phase superlens. The structure is mainly composed of a silicon rectangular nanocolumn array and a silicon dioxide substrate. In order to clearly show the arrangement of the array, the number of actual silicon rectangular columns is reduced in the model diagram; Figure 1 (b) is a unit structure model diagram of the superlens, the silicon nanocolumn has a height h = 600 nm, and the lattice constant a = 500 nm; Figure 1 (c) is a top view of the full lens of the superlens, and the lens radius is 10 μm; Figure 1 (d) is a top view of the unit cell, in which the silicon rectangular column has 12 combination modes of length (W) and width (L), and the horizontal rotation angle is θ.

[0044] Figure 2 (a) is the output electric field distribution of the x-z component under linearly polarized incidence; Figure 2 (b) and (c) are respectively the x-y component electric field distribution of the focal plane corresponding to f2 = 8 μm and f1 = 5 μm under linearly polarized incidence; Figure 2 (d) and (e) are respectively the x-z component and the x-y component of the output electric field distribution of the focal plane corresponding to f1 under LCP incidence; Figure 2 (f) and (g) are respectively the x-z component and the x-y component of the output electric field distribution of the focal plane corresponding to f2 under RCP incidence.

[0045] Figure 3 is the number of silicon rectangular columns (1-12) and the corresponding transmittance and transmission phase shift distribution.

[0046] Figure 4 (a) and (b) are respectively the phase distribution helical diagram of the output electric field obtained under LCP and RCP incidence.

[0047] Figure 5(a) is the optical force F on a polystyrene particle with a radius of 150 nm in the focal plane within the range of x = -1 μm to x = 1 μm under LCP incidence. x and F y distribution map; Figure 5 (b) is the optical potential well diagram of the particle along the x direction.

[0048] Figure 6 (a) and (b) are respectively the RCP incident and Figure 5 The optical force F on the same particle in the focal plane within the range of x = -2μm to x = 2μm x With F y Distribution plot along the x-axis; Figure 6 (c) and (d) are the potential well depth diagrams of the particle in the horizontal and vertical directions, respectively. DETAILED DESCRIPTION

[0049] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0050] The present invention proposes a fully dielectric tunable optical tweezers based on a composite phase superlens. The structural diagram of the optical tweezers is shown in FIG. Figure 1 Specifically, the metalens surface is composed of rectangular silicon nanopillars with an attached horizontal rotation angle arranged in a certain pattern. All nanopillars have the same height and are available in 12 different length and width combinations (see Table 1). The horizontal rotation angle covers the range of 0-π. As shown in the aforementioned principle section, the length and width of the rectangular nanopillars determine the transmission phase shift on the orthogonal substrate, while the rotation angle determines the geometric phase. Therefore, during the structural design process, all geometric parameters must be strictly considered to meet the requirements of independently controlling the optical response.

[0051] Table 1 Length and width combinations of the 12 rectangular silicon nanorods used

[0052] Rectangular Silicon Pillar Number Length (nm) Width (nm) 1 235 420 2 130 175 3 400 140 4 415 145 5 425 160 6 445 165 7 405 240 8 140 320 9 140 400 10 155 405 11 160 425 12 190 415

[0053] First, the lattice constant a was determined to be 500 nm. The length and width of the rectangular pillars were swept over a range of 100 nm to 450 nm with a step size of 5 nm, while the height was fixed at 600 nm. The output was the unit cell transmittance and two sets of phase shifts in orthogonal directions. A total of 71×71 rectangular pillar combinations were obtained, along with the corresponding output transmittance and phase shift.

[0054] Then all the combinations of rectangular columns are screened and the phase shift interval of 0-2π is discretized into 12 phase levels. The first step is to screen out the rectangular columns with unit transmittance greater than 0.7, and the second step is to find the transmission phase shift |φ on the orthogonal basis. x-φ y |=π(derived from equation (10)) unit structure, the error is allowed within 1%. On the basis of the first two steps, the screened phase shift (such as φ x ) matrix element is matched with 12 discrete phase levels, 12 target phase shifts and corresponding rectangular column combinations closest to them are found, and they are numbered in sequence 1-12, which is the final selected unit structure applied to the surface array of the superlens, and the transmittance and phase shift corresponding to the rectangular column number are shown in Figure 3

[0055] Then, the mapping relationship between the position coordinates of the superlens surface and the structure geometric parameters needs to be determined, so as to realize the arrangement of the unit structure and the construction of the whole lens. For the two output optical responses, the wavefront phase distribution when LCP and RCP light is incident needs to meet the following formula:

[0056]

[0057] f1 and f2 are the focal lengths of LCP and RCP light incidence respectively, λ=850nm is the working wavelength of the optical tweezers, and m=3 is the carried topological charge. In order to facilitate the representation of the cell position under the concentric circle model, the plane rectangular coordinates (x, y) are mapped to polar coordinates The mapping relationship is Substituting equation (11) can obtain the phase distribution formula in polar coordinates:

[0058]

[0059] φ + and φ - represent the wavefront phase when LCP and RCP light is input respectively. The lens surface radius R=10μm, and the total number of concentric circles The number of unit cells in each circle is equal to 6×circle number i, so the total number of rectangular column array units used by the superlens surface is 1260. By combining equation (12) and equation (10) in polar coordinates, the orthogonal transmission phase shift φ x (or φ y ) and the rotation angle θ of each coordinate can be obtained, and the required rectangular column type number and placement method are determined, and the construction of the whole lens is completed.

[0060] The all-dielectric composite phase superlens involved in the application has a working wavelength of 850nm and a topological charge m=3. Under linearly polarized light incidence, the phase distribution of the superlens satisfies equation (11) or (12), and the optical response and optical force are simulated by using the finite difference time domain (FDTD) method. Figure 2 (a) to Figure 2 ​(c) shows the three-dimensional distribution of the output electric field for linearly polarized incident light. It is easy to see that two localized modes (b: central focus c: vortex) are located at different focal planes. Changing the incident light polarization to left and right circular polarization, the changes of the output electric field distribution are shown in Figure 2 (d) and Figure 2 (g). It is easy to see that there is only one localized mode at this time, and each exists independently on the focal plane corresponding to f1 or f2.

[0061] For LCP and RCP incident, the phase distribution of the output should be independent of φ + (x,y) and φ - (x,y), Figure 4 (a) and Figure 4 (b) show the phase distribution of the two output electric fields, respectively.

[0062] Regarding the analysis and calculation of the optical force on the particles, the particles will be subjected to the combined action of optical gradient force and scattering force in the light field, but due to the high electric field enhancement on the focal plane, the scattering force in the plane can be ignored. We use the Maxwell stress tensor (MST) method to calculate the optical gradient force.

[0063] F = ∮ S (<T M >·n)dS (13)

[0064] Where <T M > represents the Maxwell stress tensor, and n is the normal vector of the outer surface S. <T M > can be expressed as

[0065]

[0066] Where D is the electric displacement, H is the magnetic field strength, E * and B * are the complex conjugate of the electric field strength and magnetic induction strength, and I is the isotropic tensor.

[0067] Under LCP incident, a spherical polystyrene (PS) particle with r = 150 nm is placed in the focal plane corresponding to the focal length f1 = 5 μm. By changing the particle's position on the x-axis in the plane at equal intervals, the distribution of the two orthogonal components of the optical force along the x-axis on the particle is calculated and analyzed according to formula (13) and formula (14). The results are shown in Figure 5 (a). The particle obtains the maximum horizontal component optical force F x at x = ± 300 nm, and the optical force direction points to x = 0. The F x distribution graph has a singularity at the origin and is symmetric about the origin. Therefore, under the dominant action of the horizontal component optical force, LCP incident mainly exhibits a central convergent trapping mode for the particle.

[0068] The potential well depth can be calculated by integrating the component of the optical force along a certain path, such as:

[0069] U x = -∫F x dx (15)

[0070] The horizontal component of the optical force F x x is integrated over the range of -1 μm to 1 μm on the x-axis, and the potential well depth curve is shown in Figs. Figure 5 (b). It is seen from the figure that the maximum well depth is obtained at x = 0, U xmax = 193.7k B T. This is the position where the particle is finally trapped, which is consistent with the trapping pattern obtained from the analysis of the optical force, and the maximum potential well depth ensures the stability of the trapping.

[0071] For RCP incidence, the particle is placed at the vortex focal plane corresponding to f2= 8 μm, and the other conditions remain the same as for LCP incidence. The two orthogonal components of the optical force F x x and F y are obtained along the x-axis, as shown in Figs. Figure 6 (a) and Figure 6 (b). It is seen from the figure that the particle obtains the maximum vertical component of the optical force F y at x = ±1 μm, while the horizontal optical force F x almost disappears at this point. Therefore, F x tends to trap the particle in the optical well at the two symmetric positions in the horizontal direction, while F y provides a downward (upward) motion trend in the vertical direction. The potential well depth curves in the two directions are shown in Figs. Figure 6 (c) and Figure 6 (d), U xmax = 127.6k B T, which is consistent with the results of the optical force.

[0072] The motion equation of the particle in the vortex optical field is described as follows:

[0073]

[0074] where F is the force experienced by the particle in the circumferential azimuthal direction, v is the rotational speed, and γ is the friction coefficient, which is defined as follows:

[0075] γ = 6πνr (17)

[0076] where r is the radius of the particle, and v is the dynamic viscosity of the medium, v = 1.81 x 10 -5 kg / (m·s)

[0077] From equation (16) and the symmetry of the optical vortex, it can be analyzed that the particle will be subjected to a light force equal to F y in the tangential direction of the ring, and the radial light force is almost zero because its size is equal to F x . Therefore, under the action of the tangential F y , the particle is captured into the ring and does a rotational motion around the ring, and its maximum rotational speed v = 1.74 x 10 - m / s. 4

[0078] The definition of the optical torque is as follows: Γ = v R (18)

[0079] where R = 1 μm is the rotational radius. According to the calculation, under RCP incidence, the maximum torque obtained by the particle is 1.74 x 10 -10 m 2 / s, that is, the particle rotational manipulation in the vortex mode is realized.

Claims

1. A fully dielectric tunable optical tweezers based on a composite phase superlens is proposed. The characteristics are: the superlens is composed of rectangular silicon (Si) nanopillars of varying sizes arranged in a concentric array with the same period to form a circular mirror surface. Each unit nanopillar is attached with a specific horizontal rotation angle. The surface array is located on a silicon dioxide (SiO2) substrate with a thickness of 1700nm. The superlens mirror radius is 10000nm.

2. According to claim 1, the metalens surface array is composed of square unit cells with rectangular silicon nanopillars as the main body, and is characterized by: The square unit cell has a lattice constant of 500 nm, and the rectangular nanopillars are 600 nm tall. The nanopillars of equal height are distinguished by varying lengths and widths, with 12 combinations ranging from 100 nm to 450 nm. These correspond to 12 phase levels uniformly distributed between 0 and 2π (Table 1). Each nanopillar is horizontally rotated by a certain angle relative to its initial position, covering the 0-π range.

3. According to claims 1 and 2, a fully dielectric, adjustable optical tweezers is realized by combining the transmission phase and the geometric phase, and comprising a SiO2 substrate and Si nanoarrays with varying lengths, widths, and rotation angles to form a complete superlens structure. The invention is characterized by: The optical tweezers operate at a wavelength of 850 nm. When circularly polarized light is incident, the metalens has a transmittance greater than 0.8 and a polarization conversion efficiency of approximately 94%. For left-handed circularly polarized light, the output field exhibits a centrally focused mode with a focal length of 5500 nm, a numerical aperture of 0.876, and a focusing efficiency of 59.2%. For right-handed circularly polarized light, the output field exhibits a closed vortex ring mode with a focal length of 8500 nm, a numerical aperture of 0.762, and a focusing efficiency of 37.6%. The two fields are controlled independently by circularly polarized light of opposite chirality. When linearly polarized light is incident, both the focused and vortex fields exist simultaneously, maintaining the original focal length and spatial distribution.

4. According to claims 1, 2, and 3, the optical tweezers are characterized by: multiple optical trapping modes that can be flexibly switched. The motion state of the particle in the field can be changed by adjusting the polarization state of the incident light, and the particle can be stably trapped in the optical trap in each manipulation mode. For a polystyrene particle with a radius of 150 nm, when left-handed circularly polarized incident, it is subjected to a horizontal optical force of a maximum of 48.37 pN / W directed toward the local center of the field, and the potential well depth at the center is about 193.7 k B When the input is right-handed circularly polarized, the maximum optical force of the particle in the radial and tangential directions is 13.90 pN / W and 10.17 pN / W, respectively, and the potential well depth inside the vortex ring is about 127.6 k B T, the maximum torque is 1.74×10 -10 m 2 / s, the above performance indicators all indicate that the optical tweezers of the present invention can meet diverse stable particle capture requirements. Table 1

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