Superlens parameter generation method, superlens and laser equipment

Abstract

The invention discloses a parameter generation method of a super lens, the super lens and laser equipment, the super lens is used for generating square ring light spots, the super lens comprises a substrate and a plurality of unit structures, the substrate comprises a super surface, the super surface comprises a plurality of unit areas, and the unit structures are arranged in the unit areas. The method comprises the following steps: determining a wavefront phase formula of incident light based on a square ring light spot; and the rotation angle of each unit structure around the height direction is determined based on a wavefront phase formula, so that the emergent phase of the incident light is accurately regulated and controlled, after the incident light passes through each unit structure, the phase of the emergent light is changed, and the light is finally focused to form a square ring light spot. Namely, based on the light and thin characteristics of the super lens, the phase of the incident light is modulated by setting the rotation angle of each unit structure of the super lens around the height direction, so that while the square ring light spot is generated, an optical lens group with a huge volume does not need to be arranged, and the volume and the mass of equipment are reduced.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and more specifically, to a method for generating parameters of a metalens, an electronic device, a metalens, and a non-volatile computer-readable laser device. Background Art

[0002] At present, in the superlens laser shaping technology, the focus is usually on how to obtain a circular ring spot, and there is little research on square ring shaping. The square ring spot is of great significance in the fields of light manipulation and laser processing. For example, in the field of laser cutting, the square ring spot has better laser cutting efficiency and cutting quality than the circular ring spot. Therefore, how to focus the laser to obtain a square ring spot is a problem that needs to be solved urgently in this field. Summary of the invention

[0003] The embodiments of the present application provide a method for generating parameters of a metalens, a metalens, and a laser device, which can generate a square ring light spot, and the device for generating the square ring light spot is relatively small in size.

[0004] A method for generating parameters of a metalens in one embodiment of the present application, the metalens is used to generate a square ring spot, the metalens includes a substrate and a plurality of unit structures, the substrate includes a metasurface, the metasurface includes a plurality of unit regions, the unit structures are arranged in the unit regions, and the method includes: determining a wavefront phase formula of incident light based on the square ring spot; determining a rotation angle of each of the unit structures around a height direction based on the wavefront phase formula.

[0005] In some embodiments, determining the rotation angle of each of the unit structures around the height direction based on the wavefront phase formula includes: determining the phase of each of the unit structures based on the wavefront phase formula of the incident light; and determining the rotation angle of each of the unit structures around the height direction based on the phase of each of the unit structures.

[0006] In some embodiments, the square ring spot includes multiple spot areas, the wavefront phase formula includes multiple wavefront phase formulas, the multiple wavefront phase formulas correspond to the multiple spot areas one by one, and the wavefront phase formulas are generated based on the corresponding spot areas respectively.

[0007] In some embodiments, the wavefront phase formula of the incident light determined based on the square ring spot includes: generating a plurality of the wavefront phase formulas based on the size of the square ring spot and the corresponding spot area.

[0008] In some embodiments, the plurality of spot areas include a first spot area, a second spot area, a third spot area, and a fourth spot area, and the first spot area, the second spot area, the third spot area, and the fourth spot area form a square ring shape, and the plurality of wavefront phase formulas include a first wavefront phase formula, a second wavefront phase formula, a third wavefront phase formula, and a fourth wavefront phase formula, and the wavefront phase formula is generated based on the size of the square ring spot and the corresponding spot area, including: generating the first wavefront phase formula based on the first spot area and the distance between the first spot area and the third spot area; generating the second wavefront phase formula based on the second spot area and the distance between the second spot area and the fourth spot area; generating the third wavefront phase formula based on the third spot area and the distance between the first spot area and the third spot area; generating the fourth wavefront phase formula based on the fourth spot area and the distance between the second spot area and the fourth spot area.

[0009] In some embodiments, the first wavefront phase formula is generated based on the first light spot area and the distance between the first light spot area and the third light spot area, including: based on the first light spot area, the distance between the first light spot area and the third light spot area, the wavelength of the incident light and the focal length of the metalens, the first wavefront phase formula is generated; based on the second light spot area, and the distance between the second light spot area and the fourth light spot area, the second wavefront phase formula is generated, including: based on the second light spot area, the distance between the second light spot area and the fourth light spot area, the wavelength of the incident light and the focal length of the metalens, the second wavefront phase formula is generated. wavefront phase formula; based on the third light spot area, and the distance between the first light spot area and the third light spot area, the third wavefront phase formula is generated, including: based on the third light spot area, the distance between the first light spot area and the third light spot area, the wavelength of the incident light and the focal length of the metalens, the third wavefront phase formula is generated; based on the fourth light spot area, and the distance between the second light spot area and the fourth light spot area, the fourth wavefront phase formula is generated, including: based on the fourth light spot area, the distance between the second light spot area and the fourth light spot area, the wavelength of the incident light and the focal length of the metalens, the fourth wavefront phase formula is generated.

[0010] In some embodiments, the first light spot region, the second light spot region, the third light spot region, and the fourth light spot region are all cylindrical waves.

[0011] In some embodiments, the phase of each of the unit structures is determined based on the wavefront phase formula of the incident light, including: determining a phase distribution formula based on each of the wavefront phase formulas; determining the position coordinates corresponding to each of the unit structures in the phase distribution formula based on the ratio of the size of the square ring spot and the size of the metasurface, and the position of the unit area where each of the unit structures is located; and determining the phase corresponding to each of the unit structures based on the position coordinates corresponding to each of the unit structures and the phase distribution formula.

[0012] In some embodiments, the method also includes: obtaining the exit phases of each incident light respectively collected when the unit structure is at different calibrated rotation angles; determining the phase of each unit structure based on the exit phase of each incident light; and establishing a mapping relationship between the rotation angle and the phase of the unit structure based on each calibrated rotation angle and the phase of the unit structure corresponding to each calibrated rotation angle.

[0013] In some embodiments, determining the rotation angle of each unit structure around the height direction based on the phase of each unit structure includes: determining the rotation angle of each unit structure around the height direction based on the mapping relationship and the phase of each unit structure.

[0014] In some embodiments, the phase includes any phase in the interval [-π, π].

[0015] The metalens of the present application is used to generate a square ring light spot. The metalens includes a substrate, a plurality of unit structures and a controller. The substrate includes a metasurface, the metasurface includes a plurality of unit areas, the unit structure is arranged in the unit area, and the controller is used to execute the parameter generation method of the metalens described in any of the above embodiments.

[0016] In some embodiments, when the rotation angle range of each of the unit structures around the height direction is [0, 180], the conversion efficiency of the metalens is greater than a preset conversion efficiency.

[0017] In certain embodiments, the substrate comprises silicon dioxide, and the unit cell structure comprises metallic gold and / or titanium dioxide.

[0018] In certain embodiments, the shape of the metalens includes at least one of a rectangle, a circle, and an ellipse.

[0019] The laser device of the present application includes: a laser emitter for emitting laser; and a superlens, wherein the superlens is used to shape the laser emitted by the laser emitter into a square ring spot, and the superlens includes the superlens described in any of the above embodiments.

[0020] The parameter generation method, superlens and laser device of the embodiment of the present application determine the wavefront phase formula of the incident light based on the square ring light spot, and then determine the rotation angle of each unit structure around the height direction based on the wavefront phase formula to accurately control the outgoing phase of the incident light. After the incident light passes through each unit structure, the phase of the outgoing light changes, and the light is finally focused to form a square ring light spot. In other words, based on the light and thin characteristics of the superlens, by setting the rotation angle of each unit structure of the superlens around the height direction, the phase of the incident light is modulated, so that when generating a square ring light spot, there is no need to set a huge optical lens group, thereby reducing the volume and mass of the equipment. When square ring light spots of different sizes are required, it is only necessary to redetermine the wavefront phase formula based on the square ring light spot to determine the rotation angle; then, by rotating each unit structure at a corresponding rotation angle, the desired square ring light spot can be obtained, which is simple to operate and highly flexible.

[0021] Additional aspects and advantages of the embodiments of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 It is a schematic diagram of an application scenario of a method for generating parameters of a metalens in certain embodiments of the present application;

[0024] Figure 2 is a flow chart of a method for generating parameters of a metalens in certain embodiments of the present application;

[0025] Figure 3 is a schematic diagram of a scenario of a method for generating parameters of a metalens in certain embodiments of the present application;

[0026] Figure 4 is a flow chart of a method for generating parameters of a metalens in certain embodiments of the present application;

[0027] Figure 5 is a flow chart of a method for generating parameters of a metalens in certain embodiments of the present application;

[0028] Figure 6 is a schematic diagram of a scenario of a method for generating parameters of a metalens in certain embodiments of the present application;

[0029] Figure 7 is a schematic diagram of a scenario of a method for generating parameters of a metalens in certain embodiments of the present application;

[0030] Figure 8 is a schematic diagram of a scenario of a method for generating parameters of a metalens in certain embodiments of the present application;

[0031] Fig. 9 is a flow chart of a method for generating parameters of a metalens in certain embodiments of the present application;

[0032] Fig.10 is a flow chart of a method for generating parameters of a metalens in certain embodiments of the present application;

[0033] Fig.11 is a flow chart of a method for generating parameters of a metalens in certain embodiments of the present application;

[0034] Fig.12 is a flow chart of a method for generating parameters of a metalens in certain embodiments of the present application;

[0035] Fig.13 is a schematic diagram of a scenario of a method for generating parameters of a metalens in certain embodiments of the present application;

[0036] Fig.14 is a schematic diagram of a scenario of a method for generating parameters of a metalens in certain embodiments of the present application;

[0037] Fig.15 It is a module schematic diagram of a parameter generation device of a metalens in certain embodiments of the present application;

[0038] Fig.16 It is a schematic diagram of the connection status of a non-volatile computer-readable storage medium and a processor in certain embodiments of the present application. DETAILED DESCRIPTION

[0039] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the embodiments of the present application, and cannot be understood as limiting the embodiments of the present application.

[0040] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one feature. In the description of this application, the meaning of "plurality" is at least two, such as two, three, unless otherwise clearly and specifically defined.

[0042] To facilitate understanding of this application, the background of this application is explained below:

[0043] In related fields, through the carefully designed geometric optical lens group, various light spots can be focused to achieve the shaping of laser beams. The shaped lasers are widely used, for example, in laser processing, laser projection, optical communication, biophotonics, light manipulation and many other fields.

[0044] To achieve light spots of various shapes, it is necessary to focus the incident laser through a carefully designed geometric optical lens group to manipulate parameters such as the light spot shape, position, phase distribution, intensity distribution, and polarization distribution, so as to obtain the amplitude distribution, polarization state, and phase modulation that meet the requirements.

[0045] In traditional geometric optics, geometric lenses achieve focusing by changing the refraction direction of incident light. Since the focusing process is limited by the refractive index of the material of the geometric lens, the geometric optical lens group often requires a larger installation space to achieve the focusing purpose, resulting in a series of problems such as huge volume and low integration of the geometric optical lens group, which affects the applicability of laser beam shaping.

[0046] The size and shape of the spot obtained by laser focusing affect the application of the spot. Taking the laser cutting scene as an example, the size and shape of the spot determine the area of ​​interaction between the laser beam and the material being cut, thereby affecting the material removal rate (the higher the removal rate, the higher the processing efficiency). In different application scenarios, the spot needs to be shaped into different shapes. For example, the circular ring-shaped spot is widely used in light manipulation to capture tiny particles. The square ring-shaped spot is widely used in laser processing, laser projection and other fields.

[0047] At present, in the annular laser shaping technology, the focus is usually on how to shape the light spot into a circular ring, and there is little research on square ring shaping. The square ring light spot is of great significance in the fields of light manipulation and laser processing.

[0048] In view of this, embodiments of the present application provide a method for generating parameters of a metalens, a metalens, and a laser device.

[0049] See also Figure 1First, the application scenarios of the technical solution of this application are introduced. The laser device provided by this application can be used for Figure 1 In the laser device 1000, the laser device 1000 may include a superlens 100 and a laser emitter 200, and the superlens 100 is used to shape the laser emitted by the laser emitter 200 into a square ring light spot.

[0050] In one embodiment, the laser transmitter may be a variable wavelength laser, a single wavelength laser, or the like.

[0051] In one embodiment, the metalens includes a substrate, a plurality of unit structures, and a controller 10. The controller 10 can be used to implement the parameter generation method of the metalens according to the embodiment of the present application.

[0052] Optionally, the substrate includes a supersurface, the supersurface includes a plurality of unit regions, and the unit structure is arranged in the unit region.

[0053] Optionally, the substrate comprises silicon dioxide, and the unit structure comprises metallic gold and / or titanium dioxide.

[0054] Optionally, the shape of the metalens includes at least one of a rectangle, a circle and an ellipse. For the convenience of description, the embodiment of the present application is described by taking the shape of the metalens as a rectangle as an example.

[0055] The following is a detailed description of the method for generating parameters of the metalens provided in this application. The method for generating parameters of the metalens provided in this application can be applied to Figure 1 In the metalens 100 shown.

[0056] The metalens is used to generate a square ring light spot, the metalens includes a substrate and a plurality of unit structures, the substrate includes a metasurface, the metasurface includes a plurality of unit regions, and the unit structure is arranged in the unit region.

[0057] See also Figure 2 , a method for generating parameters of a superlens, comprising:

[0058] Step 011: Determine the wavefront phase formula of the incident light based on the square ring spot.

[0059] The substrate includes silicon dioxide, and the unit structure includes gold and / or titanium dioxide. Gold has high optical stability and can withstand high-power laser beams, and titanium dioxide has the characteristics of high refractive index and low light loss rate; silicon dioxide has high light transmittance and low refractive index, which can improve the optical performance (polarization conversion efficiency) of the metalens and ensure the stability of the metalens during production and use.

[0060] The wavefront phase formula can represent the phase of the light wave after the unit structure is modulated, which can be expressed by the phase angle φ. The wavefront phase of the laser emitted by the laser transmitter can be modulated by the superlens to change the optical properties of the focused focal area and obtain a square ring light spot.

[0061] Specifically, in order to compress the volume of the geometric optical lens group, the superlens (similar to the geometric refractive lens, an optical metasurface that can realize lens imaging, which is based on sub-wavelength artificial structural units to control the phase and amplitude of the incident light and realize multi-wavelength off-axis focusing) came into being. Unlike the geometric lens, the superlens uses micro-nano-sized components to accurately process various elements of electromagnetic waves, such as amplitude, phase, polarization, propagation direction, etc., at the nanoscale. Therefore, the superlens has the advantages of being ultra-light and ultra-thin, and the volume is almost negligible. The superlens can realize a highly compact and integrated imaging system within a limited volume, which can replace the huge and bulky geometric optical lens group in the traditional optical system.

[0062] In the laser device, the laser emitter emits light to the metalens, and the light is modulated by the metalens to form light and dark areas, which are light spots. The size and position of the light spot are related to the wavefront phase formula of the incident light. That is, the incident light is phase modulated by each unit structure of the metalens so that the focal area (light spot) of the light is a square ring shape. Therefore, the wavefront phase formula of the incident light can be reversed according to the required square ring light spot. For example, by collecting and calculating the shape, position (or position change) and light intensity of the square ring light spot, the wavefront phase formula of the incident light is determined to determine the propagation of the incident light after modulation by the metalens.

[0063] Step 012: Determine the rotation angle of each unit structure around the height direction based on the wavefront phase formula.

[0064] Specifically, a superlens is generally constructed using a dielectric material, and the dielectric material uses the dielectric equivalent refractive index theory to control the phase of light incident on the dielectric material and emitted.

[0065] Take the unit structure as a rectangle, and the phase control based on the geometric phase control method (PB phase control method) as an example. Figure 3 , the unit structure is set on the unit area. For a rectangular, micro-nano-sized unit structure, the central axis corresponding to the long side and short side of the unit structure can be regarded as the fast axis and slow axis of the birefringent element. The PB phase modulation effect of the rectangular unit structure on the light field can be expressed by the Jones matrix as follows:

[0066]

[0067] Wherein, Et represents the electromagnetic scattering response of the unit structure under circularly polarized incident light, Ex represents the electric field scattering component of the unit structure in the x-axis direction, Ey represents the electric field scattering component of the unit structure in the y-axis direction, Mani represents the scattering matrix of the unit structure, tx represents the co-polarization transmission coefficient of the unit structure under the excitation of the electromagnetic wave linearly polarized along the x-axis direction when the unit structure is not rotated, ty represents the co-polarization transmission coefficient of the unit structure under the excitation of the electromagnetic wave linearly polarized along the y-axis direction when the unit structure is not rotated, α represents the rotation angle of the unit structure, [1,i] represents the unnormalized Jones matrix of left-handed circularly polarized light, and [1,-i] represents the unnormalized Jones matrix of right-handed circularly polarized light.

[0068] Based on the above formula, it can be known that: under the action of circularly polarized incident light, by rotating the unit structure along the z-axis (the height direction of the unit structure) by an angle of α through the PB phase, a phase modulation of 2α can be generated on the cross-polarized transmission phase, and this phase modulation has nothing to do with the wavelength of the incident light. That is, for incident light of different wavelengths, the phase difference modulation of the unit structure remains constant (all 2α).

[0069] Therefore, based on the above discussion, it can be known that the output phase of the circularly polarized incident light can be adjusted by rotating the direction of the unit structure. That is, by changing the rotation angle of the unit structure to change the incident angle of the incident light, the polarization evolution path of the incident light is changed, and then the output phase is changed to form a square ring light spot.

[0070] After determining the wavefront phase formula, the phase corresponding to the incident light that forms the square ring spot can be determined, and then the rotation angle of each unit structure around the height direction (z-axis) can be determined based on the phase of the incident light. In other words, by adjusting the rotation angle of the unit structure, the phase delay of each unit structure meets the requirements for generating a square ring spot (for example, the phase of the incident light in the square ring spot is the same), each unit structure can provide a corresponding phase delay, and after the incident light passes through each unit structure, the phase of the outgoing light changes, and finally a square ring spot is generated.

[0071] In this way, the wavefront phase formula of the incident light is determined based on the square ring spot, and then the rotation angle of each unit structure around the height direction is determined based on the wavefront phase formula, so as to accurately control the outgoing phase of the incident light. After the incident light passes through each unit structure, the phase of the outgoing light changes, and the light is finally focused to form a square ring spot. In other words, by setting the rotation angle of each unit structure of the metalens around the height direction, the phase of the incident light is modulated, thereby reducing the size and mass of the equipment while generating a square ring spot. When square ring spots of different sizes are required, it is only necessary to redetermine the wavefront phase formula based on the square ring spot to determine the rotation angle; then, by rotating each unit structure at the corresponding rotation angle, the desired square ring spot can be obtained, which is simple to operate and highly flexible.

[0072] Based on the characteristics of the superlens, there is no need to set up a huge optical lens group when generating a square ring light spot. The device has a simple structure, a small size, and a high degree of integration. The method for generating a square ring light spot in the present application can fill the research gap in the field of square ring light spots.

[0073] See also Figure 4 In some embodiments, step 012: determining the rotation angle of each unit structure around the height direction based on the wavefront phase formula includes:

[0074] Step 0121: determining the phase of each unit structure based on the wavefront phase formula of the incident light;

[0075] Step 0122: Determine the rotation angle of each unit structure around the height direction based on the phase of each unit structure.

[0076] The phase includes any phase in [-π, π].

[0077] Optionally, when the rotation angle range of each unit structure around the height direction is [0, 180] (unit: °), the conversion efficiency of the superlens is greater than a preset conversion efficiency.

[0078] The preset conversion efficiency may be 0.6, 0.7, 0.8, etc. When the conversion efficiency of the metalens is greater than the preset conversion efficiency, it can be considered that the modulation of the incident light by the metalens meets the application requirements (light intensity requirements) of the square ring light spot. For the convenience of description, the preset conversion efficiency of 0.6 is used as an example for explanation.

[0079] Specifically, as described above, unit structures with different rotation angles provide different phase delays. According to the wavefront phase formula of the incident light, the phase of each unit structure (the outgoing phase of the incident light after passing through each unit structure) can be determined, and the phase can be converted into the rotation angle of each unit structure around the height direction.

[0080] Optionally, see Figure 5 , the method further comprises:

[0081] Step 013: acquiring the outgoing phases of each incident light respectively collected when the unit structure is at different calibrated rotation angles;

[0082] Step 014: determining the phase of each unit structure based on the output phase of each incident light;

[0083] Step 015: Based on each calibrated rotation angle and the phase of the unit structure corresponding to each calibrated rotation angle, a mapping relationship between the rotation angle and the phase of the unit structure is established;

[0084] Step 012: Determine the rotation angle of each unit structure around the height direction based on the phase of each unit structure, including:

[0085] Step 0123: Based on the mapping relationship and the phase of each unit structure, the rotation angle of each unit structure around the height direction is determined respectively.

[0086] Specifically, see Figure 3 , Figure 3 A schematic diagram of a scene in which a unit structure is set on a unit area is exemplified. Take the unit structure with a length L of 0.2 micrometers (μm), a width W of 0.08μm, a height H of 0.05μm, and a period of 0.4μm*0.4μm (i.e., the spacing between unit structures is 0.4μm) as an example for explanation. Wherein, Px represents the horizontal direction of the superlens, Py represents the vertical direction of the superlens, and the rotation angle is φ. A laser emitter is used to emit light to illuminate the unit structure at different calibrated rotation angles (for example, φ=0°, 30°, 60°, 180°, etc.) (i.e., the unit structure is illuminated with incident light at different incident angles), and the exit phase of the incident light at each calibrated rotation angle is collected and measured respectively, and the corresponding exit phase of the incident light is used as the phase of the unit structure, and then a mapping relationship between each calibrated rotation angle and the phase (exit phase) of the unit structure corresponding to each calibrated rotation angle is established (such as Figure 6 As shown in Figure 2, when the phase of each unit structure is obtained, the rotation angle corresponding to the phase is determined based on the mapping relationship. When setting each calibration rotation angle, the angles in the angle range of [0,180] (unit: °) can be traversed to establish a more accurate mapping relationship. Please refer to Figure 7, when the calibrated rotation angle includes [0°, 180°], that is, when the unit structure is rotated from 0° to 180°, the phase difference of the output light of the unit structure can cover [-π, π]; and the conversion efficiency of the incident light is always greater than the preset conversion efficiency (0.6), that is, no matter how the unit structure is rotated, the superlens never resonates. In other words, the superlens of the present application meets the prerequisite that the superlens cannot undergo resonant coupling.

[0087] In this way, the phase of each unit structure is determined according to the wavefront phase formula of the incident light, and then the rotation angle of each unit structure around the height direction can be determined by looking up the mapping relationship.

[0088] In some embodiments, the square ring spot includes multiple spot areas, the wavefront phase formula includes multiple wavefront phase formulas, the multiple wavefront phase formulas correspond to the multiple spot areas one by one, and the wavefront phase formulas are generated based on the corresponding spot areas respectively.

[0089] Specifically, see Figure 8 , taking the square ring spot including 4 spot areas (which can be regarded as the 4 sides of the square ring spot) as an example, the wavefront phase formula includes multiple ones, and the wavefront phase formula corresponds to the spot area one by one, that is, the same spot area is calculated based on the same wavefront phase formula. Therefore, each wavefront phase formula can be derived according to each spot area.

[0090] See also Fig. 9 In some embodiments, step 011: determining the wavefront phase formula of the incident light based on the square ring spot includes:

[0091] Step 016: Generate multiple wavefront phase formulas based on the size of the square ring spot and the corresponding spot area.

[0092] The size of the square ring light spot may be the inner radius, outer radius, etc. of the square ring light spot (for example, see Figure 8 , which can be the inner radius of the innermost circle of the square ring spot, etc.); the size of the square ring spot can be the length of each spot area (for example, see Figure 8 , which can be the side length L of the square ring light spot) etc.

[0093] See also Fig.10 Optionally, the plurality of spot regions include a first spot region, a second spot region, a third spot region and a fourth spot region, the first spot region, the second spot region, the third spot region and the fourth spot region form a square ring shape, the plurality of wavefront phase formulas include a first wavefront phase formula, a second wavefront phase formula, a third wavefront phase formula and a fourth wavefront phase formula, step 016: based on the size of the square ring spot and the corresponding spot region, generating a wavefront phase formula, including:

[0094] Step 0161: generating a first wavefront phase formula based on the first light spot area and the distance between the first light spot area and the third light spot area;

[0095] Step 0162: generating a second wavefront phase formula based on the second light spot area and the distance between the second light spot area and the fourth light spot area;

[0096] Step 0163: generating a third wavefront phase formula based on the third light spot area and the distance between the first light spot area and the third light spot area;

[0097] Step 0164: Generate a fourth wavefront phase formula based on the fourth light spot area and the distance between the second light spot area and the fourth light spot area.

[0098] Among them, the first light spot area, the second light spot area, the third light spot area and the fourth light spot area are all cylindrical waves.

[0099] Specifically, see Figure 8 , the square ring light spot includes a first light spot area S1, a second light spot area S2, a third light spot area S3 and a fourth light spot area S4. In the vertical direction, the first light spot area S1 and the third light spot area S3 are parallel to each other, and in the horizontal direction, the second light spot area S2 and the fourth light spot area S4 are parallel to each other. The first light spot area S1, the second light spot area S2, the third light spot area S3 and the fourth light spot area S4 are connected end to end to form a square light spot. The first wavefront phase formula φ1 is generated based on the first light spot area S1, the second wavefront phase formula φ2 is generated based on the second light spot area S2, the third wavefront phase formula φ3 is generated based on the third light spot area S3, and the fourth wavefront phase formula φ4 is generated based on the fourth light spot area S4. The distance between the first light spot area S1 and the third light spot area S3 can be regarded as the side length of the side of the square ring light spot, and the distance between the second light spot area S2 and the fourth light spot area S4 can be regarded as the side length of the side of the square ring light spot.

[0100] See also Fig.11 Optionally, step 0161: based on the first light spot area and the distance between the first light spot area and the third light spot area, generating a first wavefront phase formula, including:

[0101] Step 01611: Generate a first wavefront phase formula based on the first light spot area, the distance between the first light spot area and the third light spot area, the wavelength of the incident light, and the focal length of the metalens;

[0102] Step 0162: Based on the second light spot area and the distance between the second light spot area and the fourth light spot area, a second wavefront phase formula is generated, including:

[0103] Step 01621: Generate a second wavefront phase formula based on the second light spot area, the distance between the second light spot area and the fourth light spot area, the wavelength of the incident light, and the focal length of the metalens;

[0104] Step 0163: Based on the third light spot area and the distance between the first light spot area and the third light spot area, a third wavefront phase formula is generated, including:

[0105] Step 01631: Generate a third wavefront phase formula based on the third light spot area, the distance between the first light spot area and the third light spot area, the wavelength of the incident light, and the focal length of the metalens;

[0106] Step 0164: Based on the fourth light spot area and the distance between the second light spot area and the fourth light spot area, a fourth wavefront phase formula is generated, including:

[0107] Step 01641: Generate a fourth wavefront phase formula based on the fourth light spot area, the distance between the second light spot area and the fourth light spot area, the wavelength of the incident light and the focal length of the metalens.

[0108] Specifically, the first wavefront phase formula can be:

[0109]

[0110] The second wavefront phase formula can be:

[0111]

[0112] The third wavefront phase formula can be:

[0113]

[0114] The fourth wavefront phase formula can be:

[0115]

[0116] Among them, d1 is the distance between the first light spot area and the third light spot area, d2 is the distance between the second light spot area and the fourth light spot area, λ is the wavelength of the incident light (for example, taking left-handed circularly polarized light with a wavelength of 800 nm as an example, λ=800 nm), f is the focal length of the metalens (for example, f=85 μm), x is the row index of the square ring light spot, and y is the column index of the square ring light spot.

[0117] See also Figure 8, the first wavefront phase formula corresponds to the first spot area, the third wavefront phase formula corresponds to the third spot area, taking d1=d2=16μm as an example, the distance between the straight line x=0 and the first spot area is d1 / 2=8μm, and the distance between the straight line x=0 and the third spot area is also d1 / 2=8μm, so the distance between the first spot area and the third spot area is d1=16μm. That is, the cylindrical wave of the first spot area and the cylindrical wave of the third spot area are offset by 16μm in the x direction.

[0118] Similarly, the distance between the straight line y=0 and the second light spot area is d2 / 2=8μm, and the distance between the straight line x=0 and the fourth light spot area is also d2 / 2=8μm, so the distance between the second light spot area and the fourth light spot area is d2=16μm. That is, the cylindrical wave of the second light spot area and the cylindrical wave of the fourth light spot area are 10μm apart in the y direction.

[0119] In this way, different phase differences can be given to the incident light to generate a square ring light spot.

[0120] It can be understood that after the incident light of two different wavelengths passes through the unit structure of the superlens, due to the different equivalent refractive indices of the superlens, the phases assigned are different, and the wavelengths will be focused at different positions and different focal lengths.

[0121] See also Fig.12 In some embodiments, step 0121: determining the phase of each unit structure based on the wavefront phase formula of the incident light includes:

[0122] Step 01211: Determine a phase distribution formula based on each wavefront phase formula;

[0123] Step 01212: Based on the ratio of the size of the square ring spot and the size of the metasurface, and the position of the unit area where each unit structure is located, determine the position coordinates corresponding to each unit structure in the phase distribution formula;

[0124] Step 01213: Based on the position coordinates and phase distribution formula corresponding to each unit structure, the phase corresponding to each unit structure is determined respectively.

[0125] Specifically, since light has independent propagation characteristics, each wavefront phase formula (corresponding to each phase) can be integrated into a phase of the unit structure. For example, see Figure 8 , continuing the previous example, the wavefront phase formula includes the first wavefront phase formula φ1, the second wavefront phase formula φ2, the third wavefront phase formula φ3 and the fourth wavefront phase formula φ4. Assuming that the four spot areas are all complex amplitudes with an amplitude of 1, the phase distribution formula φ is obtained by adding the four wavefront phase formulas:

[0126]

[0127] Among them, arg is used to extract the phase of the four wavefront phase formulas, and then according to the ratio of the size of the square ring spot and the size of the metasurface, refer to Figure 8 and Fig.13 ( Fig.13 In , a rectangular unit corresponds to a unit structure, the grayscale size corresponds to the phase size, the black unit structure indicates that the phase corresponding to the unit structure is -π, and the white unit structure indicates that the phase corresponding to the unit structure is π), according to the ratio between the outer diameter of the square ring spot (10-(-10)) and the side length of the metasurface (60-0); and the unit structure is set on the unit area, the position of the unit area is the position of the unit structure (for example, by establishing a coordinate system on the metasurface to determine the regional coordinates of each unit area), and then through the ratio and the position of each unit area on the metasurface (for example, through the product between the ratio and the coordinates of each area, etc.), the position coordinates corresponding to each unit area (that is, the unit structure) can be determined. Then, the position coordinates of each unit structure are substituted into the phase distribution formula for calculation to obtain the phase corresponding to each unit structure, and then based on the mapping relationship between the phase and the rotation angle, the rotation angle of each unit structure can be determined, such as Fig.14 , and then configure each unit structure with a corresponding rotation angle to obtain a super lens.

[0128] See also Fig.15 In order to better implement the parameter generation method of the metalens of the embodiment of the present application, the embodiment of the present application also provides a parameter generation device 300 of the metalens, the metalens is used to generate a square ring spot, the metalens includes a substrate and a plurality of unit structures, the substrate includes a metasurface, the metasurface includes a plurality of unit areas, the unit structure is arranged in the unit area, the parameter generation device 300 of the metalens includes a first determination module 301 and a second determination module 302, the first determination module 301 is used to determine the wavefront phase formula of the incident light based on the square ring spot; the second determination module 302 is used to determine the rotation angle of each unit structure around the height direction based on the wavefront phase formula.

[0129] In some embodiments, the second determination module 302 is further specifically configured to determine the phase of each unit structure based on a wavefront phase formula of the incident light; and determine the rotation angle of each unit structure around the height direction based on the phase of each unit structure.

[0130] In some implementations, the first determination module 301 is further configured to generate a plurality of wavefront phase formulas based on the size of the square ring spot and the corresponding spot area.

[0131] In some embodiments, the plurality of spot areas include a first spot area, a second spot area, a third spot area, and a fourth spot area, and the first spot area, the second spot area, the third spot area, and the fourth spot area form a square ring shape, and the plurality of wavefront phase formulas include a first wavefront phase formula, a second wavefront phase formula, a third wavefront phase formula, and a fourth wavefront phase formula, and the first determination module 301 is specifically further used to generate a first wavefront phase formula based on the first spot area and the distance between the first spot area and the third spot area; to generate a second wavefront phase formula based on the second spot area and the distance between the second spot area and the fourth spot area; to generate a third wavefront phase formula based on the third spot area and the distance between the first spot area and the third spot area; and to generate a fourth wavefront phase formula based on the fourth spot area and the distance between the second spot area and the fourth spot area.

[0132] In some embodiments, the first determination module 301 is also specifically used to generate a first wavefront phase formula based on the first light spot area, the distance between the first light spot area and the third light spot area, the wavelength of the incident light, and the focal length of the metalens; generate a second wavefront phase formula based on the second light spot area, the distance between the second light spot area and the fourth light spot area, the wavelength of the incident light, and the focal length of the metalens; generate a third wavefront phase formula based on the third light spot area, the distance between the first light spot area and the third light spot area, the wavelength of the incident light, and the focal length of the metalens; generate a fourth wavefront phase formula based on the fourth light spot area, the distance between the second light spot area and the fourth light spot area, the wavelength of the incident light, and the focal length of the metalens.

[0133] In some embodiments, the first determination module 301 is also specifically used to determine the phase distribution formula based on each wavefront phase formula; determine the position coordinates corresponding to each unit structure in the phase distribution formula based on the ratio of the size of the square ring spot and the size of the metasurface, and the position of the unit area where each unit structure is located; based on the position coordinates corresponding to each unit structure and the phase distribution formula, respectively determine the phase corresponding to each unit structure.

[0134] In some embodiments, the parameter generation device 300 of the metalens also includes a mapping module 303, which is used to obtain the exit phases of each incident light collected respectively when the unit structure is at different calibrated rotation angles; determine the phase of each unit structure based on the exit phase of each incident light; establish a mapping relationship between the rotation angle and the phase of the unit structure based on each calibrated rotation angle and the phase of the unit structure corresponding to each calibrated rotation angle; the second determination module 302 is specifically further used to determine the rotation angle of each unit structure around the height direction based on the mapping relationship and the phase of each unit structure.

[0135] In the above text, the parameter generation device 300 of the metalens is described from the perspective of the functional module in combination with the accompanying drawings. The functional module can be implemented in the form of hardware, can be implemented by instructions in the form of software, or can be implemented by a combination of hardware and software modules. Specifically, the steps of the method embodiment in the embodiment of the present application can be completed by the hardware integrated logic circuit and / or software instructions in the processor, and the steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware coding processor to execute, or a combination of hardware and software modules in the coding processor to execute. Optionally, the software module can be located in a mature laser device in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an electrically erasable programmable memory, a register, etc. The laser device is located in the memory, and the processor reads the information in the memory, and completes the steps in the above method embodiment in combination with its hardware.

[0136] The metalens of the embodiment of the present application is used to generate a square ring spot, and the metalens includes a substrate, a plurality of unit structures and a controller. The substrate includes a metasurface, and the metasurface includes a plurality of unit areas. The unit structure is arranged in the unit area. The controller is used to implement the parameter generation method of the metalens described in any of the above embodiments. For the sake of brevity, it will not be repeated here.

[0137] The laser device of the embodiment of the present application includes a laser emitter and a superlens. The superlens is used to shape the laser emitted by the laser emitter into a square ring spot. The superlens is the superlens described in any of the above embodiments. For the sake of brevity, it will not be repeated here.

[0138] See also Fig.16 The embodiment of the present application further provides a computer-readable laser device 500, on which a computer program 510 is stored. When the computer program 510 is executed by a processor 520, the steps of the method for generating parameters of a metalens in any of the above-mentioned embodiments are implemented. For the sake of brevity, they are not repeated here.

[0139] In the description of this specification, the descriptions with reference to the terms "certain embodiments", "in an example", "exemplarily", etc., mean that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0140] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0141] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for generating parameters of a metalens, characterized in that: The metalens is used to generate a square ring light spot, the metalens includes a substrate and a plurality of unit structures, the substrate includes a metasurface, the metasurface includes a plurality of unit regions, the unit structure is arranged in the unit region, and the method includes: Determine the wavefront phase formula of the incident light based on the square ring spot; The rotation angle of each of the unit structures around the height direction is determined based on the wavefront phase formula.

2. The method for generating parameters of a superlens according to claim 1, characterized in that: The step of determining the rotation angle of each unit structure around the height direction based on the wavefront phase formula includes: Determining the phase of each of the unit structures based on a wavefront phase formula of the incident light; The rotation angles of the unit structures around the height direction are determined based on the phases of the unit structures.

3. The method for generating parameters of a metalens according to claim 1 or 2, characterized in that: The square ring light spot includes a plurality of light spot areas, the wavefront phase formula includes a plurality of light spot areas, the plurality of wavefront phase formulas correspond to the plurality of light spot areas one by one, and the wavefront phase formulas are generated based on the corresponding light spot areas respectively.

4. The method for generating parameters of a superlens according to claim 3, characterized in that: The wavefront phase formula for determining the incident light based on the square ring spot includes: Based on the size of the square ring spot and the corresponding spot area, a plurality of wavefront phase formulas are generated.

5. The method for generating parameters of a metalens according to claim 4, characterized in that: The plurality of spot areas include a first spot area, a second spot area, a third spot area and a fourth spot area, the first spot area, the second spot area, the third spot area and the fourth spot area form a square ring shape, the plurality of wavefront phase formulas include a first wavefront phase formula, a second wavefront phase formula, a third wavefront phase formula and a fourth wavefront phase formula, and the wavefront phase formula is generated based on the size of the square ring spot and the corresponding spot area, including: Generate the first wavefront phase formula based on the first light spot area and the distance between the first light spot area and the third light spot area; Generate the second wavefront phase formula based on the second light spot area and the distance between the second light spot area and the fourth light spot area; Generate the third wavefront phase formula based on the third light spot area and the distance between the first light spot area and the third light spot area; The fourth wavefront phase formula is generated based on the fourth light spot area and the distance between the second light spot area and the fourth light spot area.

6. The method for generating parameters of a superlens according to claim 5, characterized in that: The generating the first wavefront phase formula based on the first light spot area and the distance between the first light spot area and the third light spot area comprises: Generate the first wavefront phase formula based on the first light spot area, the distance between the first light spot area and the third light spot area, the wavelength of the incident light, and the focal length of the metalens; The generating of the second wavefront phase formula based on the second light spot area and the distance between the second light spot area and the fourth light spot area comprises: Generate the second wavefront phase formula based on the second light spot area, the distance between the second light spot area and the fourth light spot area, the wavelength of the incident light, and the focal length of the metalens; Based on the third light spot area and the distance between the first light spot area and the third light spot area, the third wavefront phase formula is generated, including: Generate the third wavefront phase formula based on the third light spot area, the distance between the first light spot area and the third light spot area, the wavelength of the incident light, and the focal length of the metalens; Based on the fourth light spot area and the distance between the second light spot area and the fourth light spot area, the fourth wavefront phase formula is generated, including: The fourth wavefront phase formula is generated based on the fourth light spot area, the distance between the second light spot area and the fourth light spot area, the wavelength of the incident light, and the focal length of the metalens.

7. The method for generating parameters of a metalens according to claim 5 or 6, characterized in that: The first light spot region, the second light spot region, the third light spot region and the fourth light spot region are all cylindrical waves.

8. The method for generating parameters of a metalens according to claim 2, characterized in that: The determining the phase of each of the unit structures based on the wavefront phase formula of the incident light comprises: Determine a phase distribution formula based on each of the wavefront phase formulas; Based on the ratio of the size of the square ring spot and the size of the metasurface, and the position of the unit area where each of the unit structures is located, determining the position coordinates corresponding to each of the unit structures in the phase distribution formula; Based on the position coordinates corresponding to each of the unit structures and the phase distribution formula, the phase corresponding to each of the unit structures is determined respectively.

9. The method for generating parameters of a metalens according to claim 1, characterized in that: The method further comprises: Acquiring the outgoing phases of each incident light respectively collected when the unit structure is at different calibrated rotation angles; Determining the phase of each of the unit structures based on the exit phase of each of the incident lights; Based on each of the calibrated rotation angles and the phase of the unit structure corresponding to each of the calibrated rotation angles, a mapping relationship between the rotation angle and the phase of the unit structure is established.

10. The method for generating parameters of a metalens according to claim 9, characterized in that: The step of respectively determining the rotation angle of each unit structure around the height direction based on the phase of each unit structure comprises: Based on the mapping relationship and the phase of each of the unit structures, the rotation angle of each of the unit structures around the height direction is determined respectively.

11. The method for generating parameters of a metalens according to claim 2, wherein: The phase includes any phase in the interval [-π, π].

12. A superlens, characterized in that: The metalens is used to generate a square ring spot, and the metalens includes a substrate, a plurality of unit structures and a controller. The substrate includes a metasurface, the metasurface includes a plurality of unit areas, the unit structure is arranged in the unit area, and the controller is used to execute the parameter generation method of the metalens according to any one of claims 1 to 11.

13. The metalens according to claim 12, characterized in that When the rotation angle range of each of the unit structures around the height direction is [0, 180], the conversion efficiency of the superlens is greater than the preset conversion efficiency.

14. The metalens according to claim 12, wherein: The substrate includes silicon dioxide, and the unit structure includes metal gold and / or titanium dioxide.

15. The metalens according to claim 12, characterized in that The shape of the metalens includes at least one of a rectangle, a circle, and an ellipse.

16. A laser device comprising: A laser transmitter, used for emitting laser; and A superlens, wherein the superlens is used to shape the laser emitted by the laser emitter into a square ring spot, and the superlens comprises the superlens described in any one of claims 12 to 15.

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