A spatiotemporal modulation based nanoparticle actuation device

Abstract

The application provides a kind of nanoparticle driving device based on space-time modulation, it relates to optical technology field.The nanoparticle driving device provided by the embodiment of the application, including laser light source, deflection module and polarization modulation module;Laser light source is used to emit laser beam;Deflection module and polarization modulation module are sequentially arranged on the optical path of laser beam;Deflection module is used to modulate the distribution mode of laser beam in the direction of propagation is discrete spiral distribution;Polarization modulation module is used to modulate laser beam into circularly polarized light beam;Circularly polarized light beam is used to drive particle movement.The nanoparticle driving device provided by the embodiment of the application, by modulating the distribution mode of the direction of propagation of laser beam into discrete spiral distribution, the changing electric field of laser beam changes the orbital angular momentum of particle, so that the circularly polarized light beam output by the nanoparticle driving device can change the orbital angular momentum and spin angular momentum of particle simultaneously, realize the control of two movement dimensions of particle.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a nanoparticle driving device based on spatiotemporal modulation. Background Art

[0002] Optical manipulation technology exploits the electromagnetic force generated by electric fields on nanoparticles, enabling researchers to manipulate tiny particles like cells using lasers in a non-contact, minimally damaging manner. This technology holds broad application prospects in fields such as microphysics, colloid physics, biomedicine, and materials science.

[0003] The torque manipulation of nanoparticles in a light field is primarily achieved by regulating the magnitude of the Maxwell stress tensor at different locations on the particle. When the electromagnetic field is nonuniform, the magnitude of the Maxwell stress tensor varies across the particle, generating inconsistent forces at various locations, causing the particle to rotate. Existing technologies utilize the spin angular momentum carried by circularly polarized light fields, the orbital angular momentum carried by vortex light fields, photothermal fields, and enhanced photoinduced plasmon resonance to achieve torque manipulation of particles in a single dimension. However, comprehensive control of the torque in the remaining two dimensions remains incomplete. Summary of the Invention

[0004] An embodiment of the present invention provides a nanoparticle driving device based on spatiotemporal modulation. By modulating the propagation direction of a laser beam into a discrete spiral distribution, the changing electric field of the laser beam alters the orbital angular momentum of the particles. Furthermore, a polarization modulation module modulates the laser beam into a circularly polarized beam, which can alter the spin angular momentum of the particles. This allows the circularly polarized beam output by the nanoparticle driving device to simultaneously alter both the orbital and spin angular momentum of the particles, achieving control over both dimensions of particle motion.

[0005] An embodiment of the present invention provides a nanoparticle driving device, comprising a laser light source, a deflection module, and a polarization modulation module;

[0006] The laser light source is used to emit a laser beam;

[0007] The deflection module and the polarization modulation module are sequentially arranged on the optical path of the laser beam;

[0008] The deflection module is used to modulate the distribution of the laser beam in the propagation direction into a discrete spiral distribution;

[0009] The polarization modulation module is used to modulate the laser beam into a circularly polarized beam;

[0010] Circularly polarized light beams are used to drive particle motion.

[0011] Optionally, the deflection module includes a first acousto-optic deflection unit and a second acousto-optic deflection unit, and the first acousto-optic deflection unit and the second acousto-optic deflection unit are sequentially located on the optical path of the laser beam;

[0012] The first acousto-optic deflection unit is used to deflect the propagation direction of the laser beam in a first plane, and the first plane is parallel to the propagation direction of the laser beam and the propagation direction of the acoustic wave in the first acousto-optic deflection unit;

[0013] The second acousto-optic deflection unit is used to deflect the propagation direction of the laser beam within a second plane, and the second plane is parallel to the propagation direction of the laser beam and the propagation direction of the acoustic wave in the second acousto-optic deflection unit; the propagation direction of the acoustic wave in the first acousto-optic deflection unit intersects with the propagation direction of the acoustic wave in the second acousto-optic deflection unit.

[0014] Optionally, the deflection module further includes a first polarization modulation unit, which is arranged on the optical path of the laser beam before the first acousto-optic deflection unit;

[0015] The first polarization modulation unit is used to modulate the laser beam into a linearly polarized beam.

[0016] Optionally, the deflection module further includes a sound wave output unit;

[0017] The sound wave output unit is used to output the first sound wave to the first acousto-optic deflection unit and output the second sound wave to the second acousto-optic deflection unit;

[0018] The waveform of the first sound wave is a sine wave with a frequency offset modulated by a discrete sine wave. The waveform of the second sound wave is a sine wave with a frequency offset modulated by a discrete sine wave. The phase difference between the frequency offset modulation of the first sound wave and the second sound wave is .

[0019] Optionally, the deflection module includes a first electro-optical deflection unit and a second electro-optical deflection unit, and the first electro-optical deflection unit and the second electro-optical deflection unit are sequentially located on the optical path of the laser beam;

[0020] The first electro-optical deflection unit is used to deflect the propagation direction of the laser beam in a first plane, and the first plane is parallel to the propagation direction of the laser beam and the fast axis direction of the first electro-optical deflection unit;

[0021] The second electro-optical deflection unit is used to deflect the propagation direction of the laser beam in a second plane, and the second plane is parallel to the propagation direction of the laser beam and the fast axis direction of the second electro-optical deflection unit;

[0022] The fast axis direction of the first electro-optical deflection unit intersects with the fast axis direction of the second electro-optical deflection unit.

[0023] Optionally, the deflection module further comprises a first polarization modulation unit and a second polarization modulation unit, the first polarization modulation unit is arranged on the light path of the laser beam before the first electro-optical deflection unit, and the second polarization modulation unit is arranged on the light path of the laser beam between the first electro-optical deflection unit and the second electro-optical deflection unit.

[0024] The first polarization modulation unit is configured to modulate the laser beam into a first linearly polarized beam.

[0025] The second polarization modulation unit is configured to modulate the first linearly polarized beam into a second linearly polarized beam, and the polarization direction of the first linearly polarized beam intersects with the polarization direction of the second linearly polarized beam.

[0026] Optionally, the deflection module further comprises a voltage output unit.

[0027] The voltage output unit is configured to output a first voltage to the first electro-optical deflection unit and output a second voltage to the second electro-optical deflection unit.

[0028] The waveform of the first voltage is a discrete sine wave, and the waveform of the second voltage is a discrete sine wave, and the phase difference between the first voltage and the second voltage is .

[0029] Optionally, the polarization modulation module comprises a quarter-wave plate or a 90° Faraday rotator.

[0030] Optionally, the spatiotemporal modulation-based nanoparticle driving device further comprises a collimating lens, a beam expanding module, and a beam shrinking module.

[0031] The collimating lens is arranged on the light path of the laser beam between the laser light source and the deflection module, and is configured to collimate the laser beam.

[0032] The beam expanding module is arranged on the light path of the laser beam between the deflection module and the polarization modulation module, and is configured to expand the beam diameter of the laser beam.

[0033] The beam shrinking module is arranged on the light path of the laser beam after the polarization modulation module, and is configured to shrink the beam diameter of the laser beam.

[0034] Optionally, the spatiotemporal modulation-based nanoparticle driving device further comprises a dichroic mirror, an objective lens, a flow cell, and an image acquisition module.

[0035] The dichroic mirror is arranged on the light path of the laser beam after the polarization modulation module, and is configured to reflect the laser beam to the objective lens and transmit the image of the particles in the flow cell to the image acquisition module.

[0036] The objective lens is configured to converge the laser beam into the flow cell.

[0037] The flow cell is configured to accommodate the particles.

[0038] The image acquisition module is located on the side of the dichroic mirror away from the objective lens and is used to acquire images of particles in the flow cell.

[0039] The nanoparticle driving device based on spatiotemporal modulation provided by an embodiment of the present invention modulates the distribution of the propagation direction of the laser beam into a discrete spiral distribution, causing the propagation direction of the laser beam to change periodically over time. This allows the changing electric field of the laser beam to alter the orbital angular momentum of the particle. Furthermore, a polarization modulation module modulates the laser beam into a circularly polarized beam, which can alter the spin angular momentum of the particle. This allows the circularly polarized beam output by the nanoparticle driving device to simultaneously alter both the orbital and spin angular momentum of the particle, achieving control over both dimensions of the particle's motion.

[0040] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 This is a structural block diagram of a nanoparticle driving device based on spatiotemporal regulation provided by an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the light spot of the laser beam output by the deflection module irradiated on the incident surface of the polarization modulation module;

[0044] Figure 3 is a structural schematic diagram of a polarization module provided by an embodiment of the present invention;

[0045] Figure 4 is a schematic structural diagram of another polarization module provided by an embodiment of the present invention;

[0046] Figure 5 is a waveform diagram of a first voltage and a second voltage provided by an embodiment of the present invention;

[0047] Figure 6 This is a structural block diagram of another nanoparticle driving device based on spatiotemporal regulation provided by an embodiment of the present invention;

[0048] Figure 7 This is a structural block diagram of another nanoparticle driving device based on spatiotemporal regulation provided by an embodiment of the present invention;

[0049] Figure 8 is a plot of the relationship between the discrete spiral modulation frequency and the particle's nutation angle;

[0050] Figures 9-14 This is a graph showing the relationship between the precession angle and nutation angle of gold nanoparticles at a specific discrete spiral modulation frequency. DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0053] The embodiment of the present invention provides a nanoparticle driving device based on spatiotemporal regulation. Figure 1 This is a block diagram of a nanoparticle driving device based on spatiotemporal regulation provided by an embodiment of the present invention. Figure 1 The nanoparticle driving device based on spatiotemporal modulation includes a laser light source 100, a deflection module 200 and a polarization modulation module 300; the laser light source 100 is used to emit a laser beam; the deflection module 200 and the polarization modulation module 300 are sequentially arranged on the optical path of the laser beam; the deflection module 200 is used to modulate the distribution of the laser beam in the propagation direction into a discrete spiral distribution; the polarization modulation module 300 is used to modulate the laser beam into a circularly polarized beam; the circularly polarized beam is used to drive particle movement.

[0054] refer to Figure 1The laser light source 100 emits a laser beam, and the deflection module 200 modulates the distribution of the laser beam in the propagation direction into a discrete spiral distribution. The propagation direction of the laser beam changes periodically with time, and the propagation directions of the laser beam are discontinuous within one change period. Figure 2 This is a schematic diagram of the spot of the laser beam output by the deflection module irradiating the incident surface of the polarization modulation module. Figure 2 , the position of the light spot of the laser beam irradiated on the incident surface of the polarization modulation module 300 depends on the propagation direction of the laser beam. Within one change cycle, the light spot of the laser beam irradiated on the incident surface of the polarization modulation module 300 forms an ellipse. The laser beam output by the deflection module 200 will be incident on the polarization modulation module 300, and the polarization modulation module 300 will modulate the laser beam into a circularly polarized beam. The circularly polarized beam is then irradiated near the particle, and the changing electric field of the circularly polarized beam will drive the particle to move. The change in the electric field of the circularly polarized beam comes from two aspects: the polarization state and the propagation direction. The change in the electric field caused by the polarization state of the circularly polarized beam will change the spin angular momentum of the particle. The time-varying propagation direction of the circularly polarized beam will also cause changes in the electric field around the particle. The change in the electric field caused by the propagation direction of the circularly polarized beam will change the orbital angular momentum of the particle. Therefore, the circularly polarized beam can drive the particle to produce various modes of rotational motion.

[0055] Next, we will introduce the relationship between the particle motion state and the electric field. The optical torque on the Lorentz-Mie particle It can be expressed as:

[0056]

[0057] in is the gradient operator, is the particle's position vector, is the Maxwell stress tensor, It can be expressed as:

[0058]

[0059] in is the electric field distribution, is the conjugate of the electric displacement vector, is the magnetic induction intensity, is the magnetic field strength. is the unit tensor, To get the real part, According to the above formula, the laboratory coordinate system of the nanoparticles at different positions from the center of the laser waist and different rotation angles under a given electric field can be solved by numerical calculation method. Three-dimensional moment distribution under Using the ZXZ three-dimensional Euler rotation transformation, the particle coordinate system can be obtained Three-dimensional moment distribution under As shown in the following formula:

[0060]

[0061] in is the precession angle, is the nutation angle, is the spin angle. From this, we can derive the relationship between the moment distribution of the particle and the electric field. For disk-shaped nanoparticles with a high aspect ratio, the disk plane (i.e. plane) geometric anisotropy is not obvious, and the moment distribution will degenerate into , applying the periodic extension law of the torque when the particle rotates , which can reduce the amount of numerical calculations.

[0062] After obtaining the moment distribution of the particle, according to the kinematic formula and the law of rigid body rotation, the differential equation of the particle's three-dimensional position and rotation angle over time can be written as shown below:

[0063]

[0064] in, For Brownian force, is the moment of inertia tensor, is the angular displacement vector, where the translational resistance moment , rotational resistance torque , and are the dynamic viscous resistance and viscous resistance torque coefficient respectively. When the time domain is small enough, the finite difference time domain method is constructed using this formula to simulate and calculate the motion pattern of the particle over time. Among them, the angular displacement vector of the particle needs to be converted to the Euler angle of the indexed three-dimensional torque. The conversion formula is shown below:

[0065]

[0066] in, is the rotation matrix of the Euler rotation in the x direction, is the rotation matrix of Euler rotation in the y direction, is the rotation matrix of the ZXZ Euler rotation. The Euler angle of the latest time step is obtained by superimposing the three-dimensional angular displacements of all previous time steps. According to the above formula, the relationship between the electric field of the laser beam and the motion state of the particle can be obtained.

[0067] The spatiotemporal modulation-based nanoparticle driving device provided by an embodiment of the present invention modulates the distribution of the laser beam in the propagation direction into a discrete spiral distribution, causing the propagation direction of the laser beam to change periodically over time. This allows the changing electric field of the laser beam to alter the orbital angular momentum of the particle. Furthermore, a polarization modulation module modulates the laser beam into a circularly polarized beam, which can alter the spin angular momentum of the particle. This allows the circularly polarized beam output by the nanoparticle driving device to simultaneously alter both the orbital and spin angular momentum of the particle, achieving control over both dimensions of the particle's motion.

[0068] Figure 3 This is a schematic diagram of the structure of a polarization module provided by an embodiment of the present invention, with reference to Figure 3 The deflection module includes a first acousto-optic deflection unit 201 and a second acousto-optic deflection unit 202, which are sequentially located on the optical path of the laser beam; the first acousto-optic deflection unit 201 is used to deflect the propagation direction of the laser beam within a first plane, the first plane being parallel to the propagation direction S1 of the laser beam and the acoustic wave propagation direction S4 of the first acousto-optic deflection unit; the second acousto-optic deflection unit 202 is used to deflect the propagation direction of the laser beam within a second plane, the second plane being parallel to the propagation direction of the second laser beam S2 and the acoustic wave propagation direction S5 of the second acousto-optic deflection unit; the acoustic wave propagation direction S4 of the first acousto-optic deflection unit 201 intersects with the acoustic wave propagation direction S5 of the second acousto-optic deflection unit 202.

[0069] refer to Figure 3 The first and second AOD units 201 and 202 include acousto-optic crystals. Applying acoustic waves to the acousto-optic crystals changes the refractive index of the crystals. Therefore, by controlling the acoustic waves applied to the first and second AOD units 201 and 202, the refractive indexes of the first and second AOD units 201 and 202 can be controlled, thereby controlling the propagation direction of the laser beams passing through the first and second AOD units 201 and 202. Figure 3The first acousto-optic deflection unit 201 deflects the first laser beam S1 within a first plane, which is determined by the propagation direction of the first laser beam S1 and the propagation direction S4 of the acoustic wave of the first acousto-optic deflection unit. After passing through the first acousto-optic deflection unit 201, the first laser beam S1 becomes the second laser beam S2. The degree of deflection of the propagation direction of the first laser beam S1 after passing through the first acousto-optic deflection unit 201 varies depending on the intensity of the acoustic wave applied to the first acousto-optic deflection unit 201. The propagation direction of the second laser beam S2 includes multiple propagation directions. By controlling the intensity of the acoustic wave applied to the first acousto-optic deflection unit 201, the propagation direction of the laser beam S2 can be deflected to any of the propagation directions of the second laser beam S2. After passing through the second acousto-optic deflection unit 202, the second laser beam S2 becomes a third laser beam S3. The second acousto-optic deflection unit 202 can deflect the propagation direction of the second laser beam S2 within a second plane, which is determined by the propagation direction of the second laser beam S2 and the acoustic wave propagation direction S5 of the second acousto-optic deflection unit 202. Similarly, the degree of deflection of the propagation direction of the second laser beam S2 after passing through the second acousto-optic deflection unit 202 varies depending on the acoustic wave intensity applied to the second acousto-optic deflection unit 202. The propagation direction of the third laser beam S3 encompasses all possible propagation directions of the first laser beam S1 after passing through the first acousto-optic deflection unit 201 and the second acousto-optic deflection unit 202. In order for the deflection module to modulate the propagation direction of the laser beam in two directions, the acoustic wave propagation direction S4 of the first acousto-optic deflection unit 201 and the acoustic wave propagation direction S5 of the second acousto-optic deflection unit 202 must intersect.

[0070] To simplify the control logic of the acoustic waves applied to the first and second acousto-optic deflection units 201, 202, the acoustic wave propagation direction S4 of the first acousto-optic deflection unit 201 and the acoustic wave propagation direction S5 of the second acousto-optic deflection unit 202 can be set to be perpendicular. As a result, the first plane and the second plane are also perpendicular to each other. The first and second acousto-optic deflection units 201, 202 respectively deflect the propagation direction of the laser beam in two mutually perpendicular directions. By controlling the waveforms of the acoustic waves applied to the first and second acousto-optic deflection units 201, 202, the distribution of the laser beam in the propagation direction can be modulated into a discrete spiral distribution in the time domain. The third laser beam S3 is then modulated into a circularly polarized beam by the polarization modulation module 300.

[0071] refer to Figure 3The deflection module also includes a first polarization modulation unit 203, which is disposed on the optical path of the laser beam before the first acousto-optic deflection unit 201. The first polarization modulation unit 203 is used to modulate the laser beam into a linearly polarized beam. The principle by which the first and second acousto-optic deflection units 201 and 202 deflect the propagation direction of the laser beam is based on the acousto-optic effect, whereby acoustic waves cause the refractive index of an acousto-optic crystal to undergo periodic changes, thereby forming a Bragg grating. Modulating the laser beam into linearly polarized light can improve the diffraction efficiency of the Bragg grating, thereby improving the deflection efficiency of the first and second acousto-optic deflection units 201 and 202 in the propagation direction of the laser beam.

[0072] Optionally, the deflection module further includes an acoustic wave output unit; the acoustic wave output unit is configured to output a first acoustic wave to the first acousto-optic deflection unit and a second acoustic wave to the second acousto-optic deflection unit; the waveform of the first acoustic wave is a sine wave whose frequency offset is modulated by a discrete sine wave, the waveform of the second acoustic wave is a sine wave whose frequency offset is modulated by a discrete sine wave, and the phase difference between the frequency offset modulation of the first acoustic wave and the second acoustic wave is .

[0073] The sampling frequencies of the frequency offset modulation of the first and second sound waves are both , T is the period of the frequency offset modulation of the first and second sound waves, and the periods of the frequency offset modulation of the first and second sound waves are equal. The higher the frequency of the first sound wave, the greater the degree of deflection of the laser beam propagation direction by the first acousto-optic deflection unit. The higher the frequency of the second sound wave, the greater the degree of deflection of the laser beam propagation direction by the second acousto-optic deflection unit. Therefore, when the phase difference of the frequency offset modulation of the first and second sound waves is When the frequency of the first sound wave reaches its peak, the frequency of the second sound wave reaches its valley; when the frequency of the second sound wave reaches its peak, the frequency of the first sound wave reaches its valley. As a result, the propagation direction of the laser beam output by the deflection module changes in a spiral distribution, and the laser beam's spot on the incident surface of the polarization modulation module forms an ellipse. When the peak intensities of the first and second sound waves are equal, the laser beam's spot on the incident surface of the polarization modulation module forms a circle.

[0074] Figure 4 This is a schematic diagram of the structure of another polarization module provided by an embodiment of the present invention, referring to Figure 4The deflection module includes a first electro-optical deflection unit 204 and a second electro-optical deflection unit 205, which are sequentially located on the optical path of the laser beam; the first electro-optical deflection unit 204 is used to deflect the propagation direction of the laser beam within a first plane, which is parallel to the propagation direction of the laser beam and the fast axis direction S6 of the first electro-optical deflection unit; the second electro-optical deflection unit 205 is used to deflect the propagation direction of the laser beam within a second plane, which is parallel to the propagation direction of the laser beam and the fast axis direction S7 of the second electro-optical deflection unit; the fast axis direction S6 of the first electro-optical deflection unit 204 intersects with the fast axis direction S7 of the second electro-optical deflection unit 205.

[0075] refer to Figure 4 The first and second electro-optical deflection units 204 and 205 include electro-optical crystals. Applying a voltage to the electro-optical crystals causes a birefringence effect in the electro-optical crystals, changing their refractive index and thereby deflecting the propagation direction of the laser beam within the electro-optical crystals. Thus, by controlling the voltages applied to the first and second electro-optical deflection units 204 and 205, the refractive indexes of the first and second electro-optical deflection units 204 and 205 can be controlled, thereby controlling the propagation direction of the laser beam passing through the first and second electro-optical deflection units 204 and 205. Figure 4 The first electro-optical deflection unit 204 can deflect the propagation direction of the laser beam within a first plane. When the laser beam impinges on the incident surface of the second electro-optical deflection unit 205, the laser beam spot is offset by Δx in the x-direction. The first plane is defined by the propagation direction of the laser beam at that time and the fast axis direction S6 of the first electro-optical deflection unit. The degree of deflection of the laser beam's propagation direction after passing through the first electro-optical deflection unit 204 varies depending on the voltage strength applied to the first electro-optical deflection unit 204. The second electro-optical deflection unit 205 can deflect the propagation direction of the laser beam within a second plane, causing the projection of the laser beam spot on the xy plane to be offset by Δy in the y-direction. The second plane is defined by the propagation direction of the laser beam at that time and the fast axis direction S7 of the second electro-optical deflection unit 205. Similarly, the degree of deflection of the laser beam's propagation direction after passing through the second electro-optical deflection unit 205 varies depending on the voltage strength applied to the second electro-optical deflection unit 205. In order for the deflection module to modulate the propagation direction of the laser beam in two directions, the fast axis direction S6 of the first electro-optical deflection unit 204 and the fast axis direction S7 of the second electro-optical deflection unit 205 need to intersect.

[0076] In order to simplify the control logic of the voltage applied on the first electro-optical deflection unit 204 and the second electro-optical deflection unit 205, the fast axis direction S6 of the first electro-optical deflection unit 204 and the fast axis direction S7 of the second electro-optical deflection unit 205 can be set to be perpendicular, so that the first plane and the second plane are also perpendicular to each other, and the first electro-optical deflection unit 204 and the second electro-optical deflection unit 205 respectively deflect the propagation direction of the laser beam in two perpendicular directions. By controlling the voltage waveform applied on the first electro-optical deflection unit 204 and the second electro-optical deflection unit 205, the distribution mode of the laser beam in the propagation direction can be modulated in time domain as a discrete spiral distribution, and then the laser beam is modulated as a circularly polarized beam by the polarization modulation module 300.

[0077] Reference Figure 4 The deflection module further comprises a first polarization modulation unit 203 and a second polarization modulation unit 206, the first polarization modulation unit 203 is arranged on the optical path of the laser beam before the first electro-optical deflection unit 204, and the second polarization modulation unit 206 is arranged on the optical path of the laser beam between the first electro-optical deflection unit 204 and the second electro-optical deflection unit 205; the first polarization modulation unit 203 is used for modulating the laser beam as a first linearly polarized beam S8; the second polarization modulation unit 206 is used for modulating the first linearly polarized beam S8 as a second linearly polarized beam S9, and the polarization direction of the first linearly polarized beam S8 intersects with the polarization direction of the second linearly polarized beam S9.

[0078] Reference Figure 4 Since the first electro-optical deflection unit 204 and the second electro-optical deflection unit 205 have birefringence effect, in order to ensure that the refractive index of each polarization component of the laser beam in the first electro-optical deflection unit 204 is consistent, and the refractive index of each polarization component of the laser beam in the second electro-optical deflection unit 205 is consistent, it is necessary to ensure that the first linearly polarized beam S8 and the second linearly polarized beam S9 are linearly polarized beams, and the polarization direction of the first linearly polarized beam S8 is parallel to the fast axis direction S6 of the first electro-optical deflection unit 204, and the polarization direction of the second linearly polarized beam S9 is parallel to the fast axis direction S7 of the second electro-optical deflection unit 205. The laser beam incident on the first polarization modulation unit 203 becomes the first linearly polarized beam S8, the polarization direction of the first linearly polarized beam S8 is parallel to the fast axis direction S6 of the first electro-optical deflection unit, and the first linearly polarized beam S8 incident on the second polarization modulation unit 206 becomes the second linearly polarized beam S9, the polarization direction of the second linearly polarized beam S9 is parallel to the fast axis direction S7 of the second electro-optical deflection unit 205, so that the first linearly polarized beam S8 does not have birefringence effect in the first electro-optical deflection unit 204, and the second linearly polarized beam S9 does not have birefringence effect in the second electro-optical deflection unit 205.

[0079] Optionally, the deflection module further includes a voltage output unit; the voltage output unit is used to output a first voltage to the first electro-optical deflection unit and a second voltage to the second electro-optical deflection unit; the waveform of the first voltage is a discrete sine wave, the waveform of the second voltage is a discrete sine wave, and the phase difference between the first voltage and the second voltage is .

[0080] Figure 5 This is a waveform diagram of a first voltage and a second voltage provided by an embodiment of the present invention, with reference to Figure 5 , the first voltage V x and the second voltage V y The sampling frequencies are , where T is the first voltage V x and the second voltage V y cycle, the first voltage V x and the second voltage V y The period is equal to that of the second voltage V y The phase ratio of the first voltage V x The phase is advanced The first voltage V x The greater the intensity of the first acousto-optic deflection unit, the greater the degree of deflection of the laser beam propagation direction, and the second voltage V y The greater the intensity, the greater the degree of deflection of the laser beam propagation direction by the second acousto-optic deflection unit. Figure 5 The first voltage V x When the intensity reaches the peak, the second voltage V y The intensity of the second voltage V y When the intensity reaches the peak, the first voltage V x The intensity is 0. Therefore, the change trend of the propagation direction of the laser beam output by the deflection module is a spiral distribution, and the spot of the laser beam irradiated on the incident surface of the polarization modulation module forms an ellipse. x and the second voltage V y When the peak intensities of the laser beam and the polarization modulation module are equal, the light spot irradiated on the incident surface of the polarization modulation module forms a circle.

[0081] refer to Figure 1 、 Figure 3 and Figure 4 , the polarization modulation module includes a quarter wave plate or a 90° Faraday rotator. Figure 3 The third laser beam S3 and Figure 4 The third linearly polarized beam S10 in the image is a linearly polarized beam. When the fast axis of the quarter wave plate forms a 45° angle with the polarization direction of the linearly polarized beam, the quarter wave plate can output a circularly polarized beam. The 90° Faraday rotator can also Figure 3 The third laser beam S3 in Figure 4The third linearly polarized light beam S10 in the optical fiber is modulated into a circularly polarized light beam.

[0082] Figure 6 This is a block diagram of another nanoparticle driving device based on spatiotemporal regulation provided by an embodiment of the present invention. Figure 6 The nanoparticle driving device based on spatiotemporal modulation also includes a collimating lens 400, a beam expansion module 501 and a beam reduction module 502; the collimating lens 400 is located on the optical path of the laser beam between the laser light source 100 and the deflection module 200, and is used to collimate the laser beam; the beam expansion module 501 is located on the optical path of the laser beam between the deflection module 200 and the polarization modulation module 300, and is used to expand the beam diameter of the laser beam; the beam reduction module 502 is located on the optical path of the laser beam after the polarization modulation module 300, and is used to reduce the beam diameter of the laser beam.

[0083] refer to Figure 6 Collimating lens 400 modulates the laser beam into a parallel beam, ensuring that the laser beam does not diverge during propagation. Beam expander module 501 expands the laser beam's diameter to a size suitable for polarization modulation module 300, reducing the laser beam's power density and preventing damage to the device. Beam reducer module 502 reduces the laser beam's diameter. Together, beam expander module 501 and beam reducer module 502 improve the device's scalability, facilitating the insertion of additional devices.

[0084] Figure 7 This is a structural block diagram of another nanoparticle driving device based on spatiotemporal regulation provided by an embodiment of the present invention, with reference to Figure 7 The nanoparticle driving device based on spatiotemporal modulation also includes a dichroic mirror 600, an objective lens 700, a circulation pool 800 and an image acquisition module 900; the dichroic mirror 600 is located on the optical path of the laser beam after the polarization modulation module 300, and is used to reflect the laser beam to the objective lens 700, and transmit the image of the particles in the circulation pool 800 to the image acquisition module 900; the objective lens 700 is used to converge the laser beam into the circulation pool 800; the circulation pool 800 is used to accommodate particles; the image acquisition module 900 is located on the side of the dichroic mirror 600 away from the objective lens, and is used to acquire the image of the particles in the circulation pool 800.

[0085] refer to Figure 7 The dichroic mirror 600 has a high reflectivity for the laser beam, reflecting it toward the objective lens 700. After the objective lens 700 converges the laser beam, it enters the flow cell 800. The electric field of the laser beam can alter the particle's motion within the flow cell. The dichroic mirror 600 also has a high transmittance for particle images, allowing the image acquisition module 900 to receive and display the particle images.

[0086] For example, a nano-gold hexagonal prism with a side length of 100 nm and a height of 20 nm (a diameter of 200 nm) is used as the driven particle. When the power of the laser beam incident on the flow cell is 3 mW, the discrete spiral modulation frequency of the left-handed circularly polarized light is Under these conditions, the gold nanoparticles will rotate periodically along different rotation modes. It is the inverse of the period of change in the propagation direction of the laser beam. Figure 8 is a graph showing the relationship between the discrete spiral modulation frequency and the particle's nutation angle, Figures 9-14 This is the relationship between the precession angle and nutation angle of the nanogold hexagonal prism at a specific discrete spiral modulation frequency. Figures 8 to 14 , Figure 8 The horizontal axis is the discrete spiral modulation frequency , the vertical axis is the nutation angle of the particle, the purple curve is the minimum nutation angle, the blue curve is the average nutation angle, and the green curve is the maximum nutation angle. Figures 9-14 The number in the middle and lower part is the discrete spiral modulation frequency , the radial coordinate is the precession angle of the particle, and the circumferential coordinate is the nutation angle of the particle. When the nanogold hexagonal prism is in an upright horizontal state, it is equivalent to Figures 9-14 The origin position in the particle; when the nutation angle of the particle is When the nanogold hexagonal prism is in an inverted state. Figures 9-14 The coloring of each position on the midline segment reflects the spin rotation rate of the particle at each time , blue represents reverse spin, and orange represents forward spin. When the laser modulation frequency is low, that is, When RPS <33.4, the nanogold hexagonal prism will rotate at a fixed angle. It is periodically flipped within the range of change; when the modulation frequency of the laser is high, that is, When RPS>33.4, the nano-gold hexagonal prism will The interval near it oscillates periodically and maintains a positive spin speed to spin, where is the precession angle, is the nutation angle. When the discrete spiral modulation frequency When the frequency is within the range of 33.4RPS-121RPS, the nano-gold hexagonal prisms will undergo more complex periodic changes and will modulate the frequency of the discrete spiral. With the change of , its rotation state will undergo a more complex pattern change.

[0087] In addition, the discrete spiral modulation frequency of left-handed circularly polarized light can be adjusted To control the nutation angle The range of period variation. In the discrete spiral modulation frequency When the RPS is less than 33.4, we can control the discrete spiral modulation frequency Adjusting the minimum nutation angle of the periodic motion of nanogold hexagonal prisms When the discrete spiral modulation frequency When it increases, Steadily increasing. At discrete spiral modulation frequencies When the RPS is greater than 121, the discrete spiral modulation frequency can be controlled Adjusting the maximum nutation angle of the periodic motion of gold nanoparticles ,when When it increases, This allows for the control of the three-dimensional multimodal torque of a disk-shaped nanoparticle centered at the center of discrete helical circularly polarized light.

[0088] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A nanoparticle driving device based on spatiotemporal regulation, characterized in that: It includes a laser light source, a deflection module and a polarization modulation module; The laser light source is used to emit a laser beam; The deflection module and the polarization modulation module are sequentially arranged on the optical path of the laser beam; The deflection module is used to modulate the distribution of the laser beam in the propagation direction into a discrete spiral distribution; wherein the discrete spiral distribution means that the propagation direction of the laser beam changes periodically over time, and the propagation directions are discontinuous within a change period; The polarization modulation module is used to modulate the laser beam into a circularly polarized beam; The circularly polarized light beam is used to drive the particle movement; The deflection module includes a first acousto-optic deflection unit and a second acousto-optic deflection unit, wherein the first acousto-optic deflection unit and the second acousto-optic deflection unit are sequentially located on the optical path of the laser beam; The first acousto-optic deflection unit is used to deflect the propagation direction of the laser beam in a first plane, and the first plane is parallel to the propagation direction of the laser beam and the propagation direction of the acoustic wave in the first acousto-optic deflection unit; The second acousto-optic deflection unit is used to deflect the propagation direction of the laser beam in a second plane, where the second plane is parallel to the propagation direction of the laser beam and the propagation direction of the acoustic wave in the second acousto-optic deflection unit; the propagation direction of the acoustic wave in the first acousto-optic deflection unit intersects with the propagation direction of the acoustic wave in the second acousto-optic deflection unit; Alternatively, the deflection module includes a first electro-optical deflection unit and a second electro-optical deflection unit, and the first electro-optical deflection unit and the second electro-optical deflection unit are sequentially located on the optical path of the laser beam; The first electro-optical deflection unit is used to deflect the propagation direction of the laser beam within a first plane, and the first plane is parallel to the propagation direction of the laser beam and the fast axis direction of the first electro-optical deflection unit; The second electro-optical deflection unit is used to deflect the propagation direction of the laser beam in a second plane, and the second plane is parallel to the propagation direction of the laser beam and the fast axis direction of the second electro-optical deflection unit; A fast axis direction of the first electro-optical deflection unit intersects with a fast axis direction of the second electro-optical deflection unit.

2. The nanoparticle driving device based on spatiotemporal regulation according to claim 1, characterized in that: The deflection module further includes a first polarization modulation unit, which is arranged on the optical path of the laser beam before the first acousto-optic deflection unit; The first polarization modulation unit is used to modulate the laser beam into a linearly polarized beam.

3. The nanoparticle driving device based on spatiotemporal regulation according to claim 1, characterized in that: The deflection module also includes a sound wave output unit; The sound wave output unit is configured to output a first sound wave to the first acousto-optic deflection unit and output a second sound wave to the second acousto-optic deflection unit; The waveform of the first sound wave is a sine wave whose frequency offset is modulated by discrete sine, the waveform of the second sound wave is a sine wave whose frequency offset is modulated by discrete sine, and the phase difference between the frequency offset modulation of the first sound wave and the second sound wave is .

4. The nanoparticle driving device based on spatiotemporal regulation according to claim 1, characterized in that: The deflection module further includes a first polarization modulation unit and a second polarization modulation unit, wherein the first polarization modulation unit is arranged on the optical path of the laser beam before the first electro-optical deflection unit, and the second polarization modulation unit is located on the optical path of the laser beam between the first electro-optical deflection unit and the second electro-optical deflection unit; The first polarization modulation unit is used to modulate the laser beam into a first linearly polarized beam; The second polarization modulation unit is used to modulate the first linearly polarized light beam into a second linearly polarized light beam, and the polarization direction of the first linearly polarized light beam intersects with the polarization direction of the second linearly polarized light beam.

5. The nanoparticle driving device based on spatiotemporal regulation according to claim 1, characterized in that: The deflection module further includes a voltage output unit; The voltage output unit is configured to output a first voltage to the first electro-optical deflection unit and output a second voltage to the second electro-optical deflection unit; The waveform of the first voltage is a discrete sine wave, the waveform of the second voltage is a discrete sine wave, and the phase difference between the first voltage and the second voltage is .

6. The nanoparticle driving device based on spatiotemporal regulation according to claim 1, characterized in that: The polarization modulation module includes a quarter wave plate or a 90° Faraday rotator.

7. The nanoparticle driving device based on spatiotemporal regulation according to claim 1, characterized in that: The nanoparticle driving device based on spatiotemporal regulation further includes a collimating lens, a beam expansion module and a beam reduction module; The collimating lens is located on the optical path of the laser beam between the laser light source and the deflection module, and is used to collimate the laser beam; The beam expansion module is located on the optical path of the laser beam between the deflection module and the polarization modulation module, and is used to expand the beam diameter of the laser beam; The beam reduction module is located on the optical path of the laser beam after the polarization modulation module, and is used to reduce the beam diameter of the laser beam.

8. The nanoparticle driving device based on spatiotemporal regulation according to claim 1, characterized in that: The nanoparticle driving device based on spatiotemporal regulation further includes a dichroic mirror, an objective lens, a flow cell and an image acquisition module; The dichroic mirror is located on the optical path of the laser beam after the polarization modulation module, and is used to reflect the laser beam to the objective lens and transmit the image of the particles in the flow cell to the image acquisition module; The objective lens is used to converge the laser beam into the flow cell; The flow cell is used to accommodate particles; The image acquisition module is located on a side of the dichroic mirror away from the objective lens, and is used to acquire images of the particles in the circulation pool.

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