A multi-well optical tweezers superlens based on optical phase change material

Abstract

The present invention belongs to the field of optical tweezers technology, and specifically relates to a multi-well optical tweezers super lens based on optical phase change materials, comprising: a plurality of optical phase change material nano-square pillars, an ITO layer and a substrate, wherein the plurality of optical phase change material nano-square pillars are arranged in at least two regions on the ITO layer, and the temperature of the ITO layer is quickly adjusted so that the optical phase change material nano-square pillars in each region can realize mutual conversion between a crystalline state and an amorphous state, and when the incident light power is kept constant, when the nano-square pillars are in a crystalline state, particles can be stably captured in 3D; and when the optical phase change material nano-square pillars are in an amorphous state, particles cannot be captured in 3D, thereby realizing controllable 3D capture of particles. By dividing the optical phase change material nano-square pillars distributed on the surface of the super lens into multiple regions, controllable 3D capture of more particles is realized, and capture patterns of different shapes are formed, further increasing the efficiency of the optical tweezers.

Description

Technical Field

[0001] The invention belongs to the technical field of optical tweezers, and in particular relates to a multi-well optical tweezers superlens based on optical phase change materials. Background Art

[0002] Optical tweezers technology can achieve non-contact capture and manipulation of a variety of particles, and plays an important role in the fields of biology and physics. In recent years, in order to improve the capture performance of optical tweezers, multi-well optical tweezers have gradually become a research hotspot, and are mainly used in cell classification, force measurement between particles, and optical tweezers imaging and printing. At present, multi-well optical tweezers can be realized through holographic optical tweezers technology, multi-beam interference, fiber optic imaging and other methods, and ultimately achieve the simultaneous capture and manipulation of multiple particles.

[0003] With the rapid development of metasurface technology, superlenses have been successfully applied to optical tweezers systems with their advantages of high integration and ultra-high numerical aperture (NA), and have achieved the capture and manipulation of nanoscale particles. The application of superlenses in the field of multi-well optical tweezers has achieved the capture and manipulation of microparticles by polarization-sensitive multi-focal vortex superlenses, as well as the integration of optical tweezers and optical wrenches on one superlens to form a dual focal plane to capture and manipulate particles. However, the superlenses currently used in the field of multi-well optical tweezers cannot achieve controllable focus points, and multiple focal points can only appear and disappear at the same time. Therefore, only one way of particle capture can be completed, which reduces the flexibility and efficiency of particle capture and manipulation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a multi-well optical tweezers superlens based on optical phase change material, which can realize multiple ways of capturing particles and form capture patterns of various shapes by using only the same superlens, thereby improving the flexibility and efficiency of optical tweezers.

[0005] Based on the above purpose, the present invention provides a multi-well optical tweezers superlens based on optical phase change material, comprising: a plurality of optical phase change material nano-square pillars, an ITO layer and a substrate, wherein the plurality of optical phase change material nano-square pillars are arranged in at least two regions on the ITO layer, and the optical phase change material nano-square pillars in each region can realize mutual conversion between crystalline state and amorphous state by adjusting the temperature of the ITO layer;

[0006] When the optical phase change material nano-square pillars in each area are in a crystalline state, the incident wave can form a focus through each area, but when they are in an amorphous state, no focus can be formed.

[0007] Optionally, the surface of the ITO layer is divided into a grid composed of multiple unit structures, and an optical phase change material nano-square column is arranged at the center of each unit structure, and the length and width of the optical phase change material nano-square column are both smaller than the length of the unit structure.

[0008] Optionally, the length P of the unit structure is 1 / 2λ, where λ is the wavelength of the incident wave.

[0009] Optionally, the unit structure is a square, and the adjacent two sides of the unit structure are divided into x and y axes, and the vertical direction is the z axis. The rotation angle θ of the optical phase change material nano-square column is the angle between the length direction of the optical phase change material nano-square column and the x axis. The response relationship between the rotation angle θ and the PB phase is: is the phase corresponding to each region of the superlens.

[0010] Optionally, the height H of the optical phase change material nano-square column is 1-1.5 μm, and the length L and width W are both 100 nm-400 nm.

[0011] Optionally, the optical phase change material is one of Sb2S3, GSST and GST.

[0012] Optionally, the thickness of the ITO layer does not exceed 0.03 μm.

[0013] Optionally, the ITO layer is a thin film formed by vapor deposition or sputtering of ITO onto the surface of the substrate.

[0014] Optionally, the method for forming the optical phase change material nano-square pillars is: firstly generating them on the surface of the ITO layer by one of electron beam evaporation, chemical vapor deposition and molecular beam epitaxy, and then forming them by electron photolithography process.

[0015] Optionally, the substrate material is SiO2.

[0016] The beneficial effects of the present invention are as follows: the multi-well optical tweezers superlens based on optical phase change material provided by the present invention is used for controllable 3D capture of particles. When the incident light power is kept constant, when the nano-square pillars of the optical phase change material are in a crystalline state, the particles can be stably captured in 3D; and when the nano-square pillars of the optical phase change material are in an amorphous state, the particles cannot be captured in 3D, thereby achieving controllable 3D capture of particles. By dividing the nano-square pillars of the optical phase change material distributed on the surface of the superlens into multiple regions, controllable 3D capture of more particles is achieved, and capture patterns of different shapes are formed, further increasing the efficiency of the optical tweezers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A structural diagram of a superlens for double-well optical tweezers provided in an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of the three-dimensional structure of a unit structure of a metalens provided in an embodiment of the present invention;

[0019] Figure 3 A top view of a unit structure of a metalens provided by an embodiment of the present invention;

[0020] Figure 4 A diagram of the paths of incident light and outgoing light passing through a metalens provided in an embodiment of the present invention;

[0021] Figure 5 PCE diagrams of nano-square pillars with different widths and lengths of Sb2S3 in an amorphous state provided by an embodiment of the present invention;

[0022] Figure 6 PCE diagrams of nano-square pillars with different widths and lengths of Sb2S3 in a crystalline state provided by an embodiment of the present invention;

[0023] Figure 7 A graph showing the relationship between phase and PCE and rotation angle provided in an embodiment of the present invention;

[0024] Figure 8 Intensity distribution diagrams of the superlens of the double-well optical tweezers provided in an embodiment of the present invention in the xz plane and the xy plane respectively;

[0025] Fig. 9 The F applied to the particles provided in the embodiment of the present invention x and F z Relationship diagrams with x displacement and z displacement respectively;

[0026] Fig.10 When the Sb2S3 nano-square pillars of the double-well optical tweezers provided in the embodiment of the present invention are in a crystalline state, F x and F z Potential well depth map of ;

[0027] Fig.11 A structural diagram of a superlens for multi-well optical tweezers provided in an embodiment of the present invention;

[0028] Fig.12 Intensity distribution diagrams of the superlens of the multi-well optical tweezers provided in an embodiment of the present invention in the xy plane and the xz plane respectively;

[0029] Fig.13 The Sb2S3 particles in the middle region of the superlens provided by the embodiment of the present invention are subjected to F in the crystalline and amorphous states. x Relationship with x displacement;

[0030] Fig.14 The Sb2S3 particles in the middle region of the superlens provided by the embodiment of the present invention are subjected to F in the crystalline and amorphous states. zRelationship with z displacement;

[0031] Fig.15 The Sb2S3 in the middle region of the superlens provided by the embodiment of the present invention is in the crystalline state. x and F z Potential well depth map of ;

[0032] Fig.16 The xy plane and xz plane intensity distribution diagrams of the six focusing states of the metalens provided in an embodiment of the present invention.

[0033] In the figure: 10, optical phase change material nano-square pillars; 20, ITO layer; 30, substrate. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0035] Example 1

[0036] like Figure 1 As shown, the present invention provides a multi-well optical tweezers super lens based on optical phase change material, and an optical phase change material nano-square column 10 (hereinafter referred to as Sb2S3 nano-square column) is prepared by using Sb2S3 as an optical phase change material, wherein the diameter of the super lens is 25μm, the working wavelength is 1064nm, the incident wavelength is right-handed circularly polarized light (RCP), and the output light field is left-handed circularly polarized light (LCP). The super lens is composed of an optical phase change material Sb2S3 nano-square column, an ITO layer 20 (ITO is an N-type oxide semiconductor-indium tin oxide, and the ITO film is an indium tin oxide semiconductor transparent conductive film, which usually has two performance indicators: resistivity and transmittance.) and a SiO2 substrate 30. The Sb2S3 nano-square column is first generated on the surface of the ITO layer 20 by electron beam evaporation, chemical vapor deposition, molecular beam epitaxy, etc., and then formed by an electron lithography process. The super lens is divided into two regions, A and B, and each region can realize the mutual conversion between the crystalline state and the amorphous state of the Sb2S3 nano-square column.

[0037] When the Sb2S3 nano-square pillars are crystalline, light can pass through them; when the Sb2S3 nano-square pillars are amorphous, light can hardly pass through them. Figure 1 (a) When the Sb2S3 in regions A and B are both in a crystalline state, two focal points can be formed. Figure 1 (b) When the Sb2S3 in region A is in a crystalline state and the Sb2S3 in region B is in an amorphous state, a focus can be formed only in region A. Figure 1 (c) When the Sb2S3 in region A is in an amorphous state and the Sb2S3 in region B is in a crystalline state, only region B can form a focus. Figure 1(d) When the Sb2S3 in both regions A (y>0) and B (y<0) are in the amorphous state, no focus is formed in either region, and the center of the superlens is taken as the origin of the coordinates. Therefore, when the incident light power remains constant, the focusing state of the superlens can be flexibly adjusted by simply controlling the state of Sb2S3.

[0038] The A (y>0) and B (y<0) regions of the metalens correspond to two different phase distributions. The phase distribution corresponding to region A is:

[0039]

[0040] The phase distribution corresponding to area B is:

[0041]

[0042] Where (x, y) represents the coordinates of the metalens surface, (x A ,y A ) is the focal coordinate, λ is the wavelength of the incident wave, and f is the focal length. A ,y A )=(5μm,0), the focal length f of area A and area B are both 2.5μm. For the response phase, the Pancharatnanm-Berry (PB) phase is used to implement it.

[0043] The unit structure of the superlens is as follows Figure 2-Figure 4 As shown, the unit structure is a square, where the square is a square or a rectangle, P is the period of the unit structure (i.e. the length of one side, which is the length of the longer side of the rectangle), and the value is 0.5μm, which is approximately 1 / 2λ. The ITO layer 20 mainly realizes the rapid temperature regulation function, and the thickness T is 0.03μm. In order to meet the 2π distribution of the unit structure phase, the height H of the Sb2S3 nano-square column is set to 1μm. W and L are the width and length of the Sb2S3 nano-square column, which can be obtained by subsequent optimization. The angle between the nano-square column and the x-axis is θ. When the incident light is LCP, according to the principle of the Jones matrix, the output light field of the unit structure is:

[0044]

[0045] in, represents the polarization state of light, and α is the propagation constant. The output light field contains the same polarized light with only amplitude modulation and the cross-polarized light with phase modulation, and the response relationship between the rotation angle θ of the nano-principle and the PB phase is The crystalline and amorphous states of the Sb2S3 optical phase change can be reversibly converted by temperature regulation. The ITO material has sufficient conductivity and can be heated by Joule to heat the Sb2S3 nano-pillars. Therefore, by applying an appropriate current pulse (~0.3V), the temperature can be quickly adjusted, so that the state of the Sb2S3 nano-pillars can be reversibly adjusted. The ITO layer 20 in different areas of the super lens can also be irradiated with a laser to quickly heat the ITO layer 20 to achieve the transition between the crystalline and amorphous states of the optical phase change material nano-pillars 10. The refractive index at a wavelength of 1064nm is 3.4 and 2.6, respectively, and the loss is close to 0. In order to achieve the controllability of the super lens at the focus and the controllability of the 3D capture of particles in subsequent experiments, the polarization conversion efficiency (PCE) of the Sb2S3 nano-pillars in the amorphous state needs to be minimized, so we can choose to sacrifice a little PCE in the crystalline state. The definition of PCE is as follows (the incident light is LCP):

[0046]

[0047] The finite-difference time-domain (FDTD) method was used to scan the parameters of L and W of the nano-square pillars, where the range of L and W was 100nm-400nm with a step size of 10nm. The simulation boundaries were set to perfectly matched layers (PML) and the minimum grid unit was set to 10nm. Figure 5 and Figure 6 The PCE of Sb2S3 nano-square pillars in amorphous and crystalline states. Finally, we chose L of the nano-square pillars to be 220nm and W to be 160nm. Figure 7 The phase and PCE of nano-square pillars with L = 220nm and W = 160nm are shown to change with θ. The Sb2S3 nano-square pillars completely cover the 2π phase distribution in both crystalline and amorphous states and satisfy PCE has little to do with θ, and the average PCE of Sb2S3 nanosquare pillars in the crystalline state is about 50%, and in the amorphous state is about 10%.

[0048] Figure 8 The intensity distribution diagram of the superlens in the xz plane and the xy (z = 3.3 μm) plane is shown, with a total of 4 states. Among them, when the Sb2S3 in the two regions of the superlens A and B are both in the crystalline state, two focal points will be formed, such as Figure 8(ab) As shown. The actual focusing positions are (-4.9μm, 0, 3.3μm) and (4.9μm, 0, 3.3μm), which are not much different from the original design values. The full width at half maximum (FWHM) at the focus is 0.56μm. When only the Sb2S3 in area A of the superlens is in the crystalline state, the actual focusing position is only (-4.9μm, 0, 3.3μm), and the FWHM is 0.56μm. Figure 8 (cd) When only the Sb2S3 in the B region of the superlens is in the crystalline state, the actual focusing position is only (4.9μm, 0, 3.3μm), and the FWHM is 0.56μm, as shown in Figure 8 When the Sb2S3 in the A and B regions of the super lens are both in the amorphous state, no focus is formed in the x direction, as shown in Figure 8 In particular, the contrast between the maximum intensity distribution at the focus of the Sb2S3 superlens in the crystalline state and the amorphous state can reach 10, achieving controllable dual focus.

[0049] Light force calculation:

[0050] The numerical calculation of the optical force is obtained by integrating the Maxwell stress tensor (MST) on the virtual closed surface s on the surface of the SiO2 particle. The calculation formula of the optical force F is as follows:

[0051]

[0052] in is the normal vector, s is the surface area of ​​SiO2 particles, T ij It is MST.

[0053]

[0054] Where ε and μ are constants, which are the dielectric constant and magnetic permeability respectively. E and H are the electric and magnetic fields obtained by the FDTD method. * represents a conjugate complex number. i and j can be in the x, y and z directions. δ ij is Kroneckerdelta. Therefore T ij It can be expanded in three directions: x, y and z:

[0055]

[0056] The optical trap stiffness k can be used to evaluate the stability of particle capture and is calculated by the following formula:

[0057] F=-k(xx o ) (8)

[0058] Where F is the light force. Here we take the maximum F for calculation. x is the position of the particle when F is the maximum value. o is the equilibrium point position. The displacement integral of the optical force along its capture direction can be expressed by the potential well depth U:

[0059]

[0060] Where F is the optical force and x is the particle position. We use the FDTD method to simulate the double-well optical tweezers based on optical phase change and superlens and verify its controllable effect on particle 3D capture. The capture environment is air (n = 1) and the incident light power is kept at 100mW. The lateral optical force F exerted on two SiO2 particles with a radius of 250nm (the diameter is smaller than the FWHM of the focus) around (-4.9μm, 0, 3.3μm) and (4.9μm, 0, 3.3μm) under the four focusing states of the superlens is calculated respectively. x and the axial optical force F z ,like Fig. 9 The dark curve represents the relationship between the optical force on SiO2 particles and the x-displacement and z-displacement when the superlens Sb2S3 is in the amorphous state, and the light curve represents the relationship between the optical force on SiO2 particles and the x-displacement and z-displacement when the superlens Sb2S3 is in the crystalline state.

[0061] When the Sb2S3 in regions A and B are both in a crystalline state, the F x and F z Distribution Fig. 9 (a1) and (a2) are shown in state 1. The maximum F x and k x About 0.77pN and 25.7pNμm -1 W -1 , the maximum F that particles in region B experience x and k x Both about 0.86pN and 37.4pNμm -1 W -1 In addition, F z The distribution in the z direction is asymmetric, which is caused by the uneven distribution of the focus intensity in the z direction. The maximum and minimum F z are approximately 0.60pN and 0.22pN respectively, k z Both are about 10.0pNμm -1 W -1Therefore, the two SiO2 particles can be stably captured in 3D at different focal points, and the equilibrium points are at (-4.97μm, 0, 3.6μm) and (4.97μm, 0, 3.6μm). When the Sb2S3 in region A is in a crystalline state and the Sb2S3 in region B is in an amorphous state, the F of the two SiO2 particles at different focal points is x and F z Distribution Fig. 9 (b1) and (b2) are shown in state 2. The F of particles in region A x and F z It is basically the same as in state 1, and 3D capture of particles can be achieved. The maximum F in region B x and k x About 0.08pN and 4pNμm -1 W -1 , maximum and minimum F z About 0.08pN and 0.01pN, k z About 0.69pNμm -1 W -1 , are about 1 / 10 of their crystalline state, and their minimum F z It is also much smaller than the maximum F z , and is closer to 0, so the capture of particles in the z direction is unstable. This is mainly because the uneven distribution of light intensity causes the scattering force on the particles to be much greater than the gradient force. When the Sb2S3 in area B is in a crystalline state and the Sb2S3 in area A is in an amorphous state, the F of the two SiO2 particles at different focal points is x and F z Distribution Fig. 9 (c1) and (c2) are shown in state 3. The F of particles in region B x and F z It is basically consistent with state 1, which can achieve stable 3D capture of particles. The maximum F in area A x and k x About 0.06pN and 2.0pNμm -1 W -1 , the maximum and minimum F z About 0.06pN and 0.01pN, k z Both are about 0.69pNμm -1 W -1 , are about 1 / 10 of their crystalline state, and similarly, their minimum F z Much smaller than the maximum F z And closer to 0, so that the stable 3D capture of SiO2 particles cannot be achieved. When the Sb2S3 in regions A and B are both in the amorphous state, Fig. 9 (d1) and (d2) are shown in state 4. The particles in regions A and B are subjected to Fx and maximum F z They are consistent with states 3 and 2 respectively, but the minimum F z It is further reduced to 0.006pN. This may be due to the fact that the incident light in regions A and B is basically unable to penetrate, the light intensity is weakened at the focus, and the light intensity distribution in the z direction is uneven, which ultimately makes the two SiO2 particles completely unable to be captured in the z direction. It can be seen from the four states that the double-well optical tweezers based on optical phase change and superlens achieve controllable 3D capture of particles. In addition, parts A and B are independent and basically do not affect each other, so we can adjust the Sb2S3 state of each part of the superlens individually to flexibly capture particles.

[0062] The potential well depth U of Sb2S3 in the crystalline state in the A and B regions of the superlens is further calculated and compared with K B T is normalized, where K B is the Boltzmann constant (1.38e-23 J / K), and T is the temperature (300K).

[0063] Fig.10 The U of the A and B regions of the metalens in the crystalline state is shown. x and U z .

[0064] Fig.10 (ab) is the metalens A and B region F x The potential well depth Ux diagram, Fig.10 (cd) is the potential well depth Uz diagram of Fz. The equilibrium point is the maximum potential well depth, and the maximum Uz in the A and B regions is x They are 68.3×K B T and 96.4×K B T,U z Both are 123.0×K B T. Among them, all potential well depth values ​​are much larger than K B T, indicating that in the superlens used for double-well optical tweezers, stable 3D capture of particles can be achieved when the Sb2S3 in regions A and B are in the crystalline state.

[0065] Example 2

[0066] In order to further improve the efficiency of the optical tweezers system, a superlens with a diameter of 30μm based on the optical phase change material Sb2S3 was designed and used for controllable multi-well optical tweezers. Its design idea is basically the same as that of the double-well optical tweezers. The superlens is divided into 9 regions, and the phase distribution formula of each region is as follows:

[0067]

[0068] Here, i represents the 9 regions of the superlens, and λ and f are also set to 1064nm and 2.5μm. Similarly, when the Sb2S3 in each region is in a crystalline state, a focus is formed, and when the Sb2S3 is in an amorphous state, no focus is formed, such as Fig.11 As shown in (ab), the white dot (or bright spot) is the focus. The incident light of the super lens is RCP, and the outgoing light is LCP.

[0069] Fig.11 (a) shows the structural diagram when the Sb2S3 in the middle area of ​​the superlens is in an amorphous state and the Sb2S3 in the remaining areas are in a crystalline state. Fig.12 (cd) shows its intensity distribution diagram on the xy (z = 3.3 μm) plane and the xz plane. It can be seen that the intensity of the focal spot in the virtual box on the xy plane is significantly smaller than the surrounding focal spots. On the xz plane, the actual position of the focus is at z = 3.3 μm, which is not much different from the designed position, and the FWHM is 0.62 μm. In particular, the contrast of the maximum value of the intensity distribution at the focus in the crystalline and amorphous states can reach 10, realizing the controllable formation and disappearance of the focus. Fig.11 (b) shows the structure of Sb2S3 in all regions in the crystalline state, and the corresponding xy (z = 3.3 μm) and xz intensity distribution diagrams are shown in Figure 2. Fig.12 As shown in (ef), all regions of the metalens form a focus, and the FWHMs are not much different, which are 0.56μm, 0.64μm and 0.56μm respectively.

[0070] Fig.12 (c) and Fig.12 (e) The Sb2S3 in the dotted line area is in the crystalline and amorphous state. The SiO2 particles with a radius of 0.25 μm are subjected to F x and F z Relationship with x displacement and z displacement respectively.

[0071] Fig.13 is the F received by SiO2 particles x The relationship between the x displacement and the maximum F x and k x 0.6pN and 20pNμm -1 W -1 , and the maximum F in the amorphous state x and k x 0.04PN and 1.3pNμm -1 W -1 , only about 1 / 10 of its crystalline state, F x The stability is weak.

[0072] Fig.14 SiO2 particles are subjected to F zRelationship with z displacement. In the crystalline state, the maximum and minimum F z They are 0.49pN and 0.05pN respectively, k z 3pNμm -1 W -1 , the equilibrium point is (0, 0, 5.1μm). In the amorphous state, the maximum and minimum Fz of SiO2 particles are 0.06pN and 0.007pN respectively, k z 0.3pNμm -1 W -1 , are about 1 / 10 of the crystalline state, and the minimum F z Also approximately the maximum F z The z-direction is 1 / 10 of the original z-direction, and is closer to 0. Therefore, the particle cannot be stably captured in the z direction. This is also caused by the uneven distribution of light intensity, which causes the scattering force to be much greater than the gradient force. Therefore, the middle area of ​​the superlens can achieve controllable 3D capture of particles.

[0073] Fig.15 (cd) shows the Sb2S3 in the middle region in the crystalline state. x and F z The potential well depth, U x and U z The maximum potential well depths are 64.2×K B T and 153.9×K B T, proving that stable 3D capture of particles can be achieved. Therefore, it can be extended to the other 8 regions of the superlens to achieve controllable 3D capture of multiple particles at the same time.

[0074] Based on the above theoretical and simulation analysis for controllable 3D capture of particles by multi-well optical tweezers, we can simultaneously manipulate and capture multiple SiO2 particles and arrange them into arbitrary shapes. Fig.16 (ab) and (gi) are the intensity distribution diagrams in the xy (z=3.3m) plane. Fig.16 (df) and (jl) are the corresponding xz plane intensity distribution diagrams. Each region in the superlens can control the conversion between the crystalline and amorphous states of Sb2S3 and realize the controllable 3D capture of particles. Therefore, multiple ways of particle capture and formation of capture patterns of various shapes can be achieved by using only the same superlens, further improving the efficiency of optical tweezers.

[0075] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0076] One or more embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A multi-well optical tweezers superlens based on optical phase change material, characterized in that: include: A plurality of optical phase change material nano-square pillars (10), an ITO layer (20) and a substrate (30), wherein the plurality of optical phase change material nano-square pillars (10) are arranged in at least two regions on the ITO layer (20), and the optical phase change material nano-square pillars (10) in each region can realize mutual conversion between a crystalline state and an amorphous state by adjusting the temperature of the ITO layer (20); When the optical phase change material nano-square pillars (10) in each region are in a crystalline state, an incident wave can form a focus through each region.

2. The multi-well optical tweezers superlens based on optical phase change material according to claim 1, characterized in that: The surface of the ITO layer (20) is divided into a grid composed of a plurality of unit structures, and an optical phase change material nano-square column (10) is arranged at the center of each unit structure, and the optical phase change material nano-square column (10) does not exceed the unit structure.

3. The multi-well optical tweezers superlens based on optical phase change material according to claim 2, characterized in that: The length P of the unit structure is 1 / 2λ, where λ is the wavelength of the incident wave.

4. The multi-well optical tweezers superlens based on optical phase change material according to claim 3, characterized in that: The unit structure is square, and the adjacent two sides of the unit structure are divided into x-axis and y-axis, and the vertical direction is z-axis. The rotation angle θ of the optical phase change material nano-square pillar (10) is the angle between the length direction of the optical phase change material nano-square pillar (10) and the x-axis. The response relationship between the rotation angle θ and the PB phase is: is the phase corresponding to each region of the superlens.

5. The multi-well optical tweezers superlens based on optical phase change material according to claim 1, characterized in that: The height H of the optical phase change material nano-square column (10) is 1-1.5 μm, and the length L and width W both vary in the range of 100 nm to 400 nm.

6. The multi-well optical tweezers superlens based on optical phase change material according to claim 1, characterized in that: The optical phase change material is one of Sb2S3, GSST and GST.

7. The multi-well optical tweezers superlens based on optical phase change material according to claim 1, characterized in that: The thickness of the ITO layer (20) does not exceed 0.03 μm.

8. The multi-well optical tweezers superlens based on optical phase change material according to claim 1, characterized in that: The ITO layer (20) is a thin film formed by vapor deposition or sputtering of ITO onto the surface of the substrate (30).

9. The multi-well optical tweezers superlens based on optical phase change material according to any one of claims 1 to 8, characterized in that: The method for forming the optical phase change material nano-square column (10) is as follows: firstly, it is generated on the surface of the ITO layer (20) by one of electron beam evaporation, chemical vapor deposition and molecular beam epitaxy, and then formed by electron photolithography.

10. The multi-well optical tweezers superlens based on optical phase change material according to any one of claims 1 to 8, characterized in that: The substrate (30) is made of SiO2.

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