A device for generating a reconfigurable multi-potential-well SPPs vector vortex optical tweezer excited by a single beam of light

Abstract

The present invention discloses a device for generating a reconfigurable multi-potential-well SPPs vector vortex optical tweezer excited by a single beam of light, comprising: a source module, a beam expanding and collimating module arranged on one side of the light source module, an excitation beam generating and excitation light field modulating module arranged on one side of the beam expanding and collimating module, a motion control module arranged on one side of the excitation beam generating and excitation light field modulating module, an illumination module arranged above the motion control module, and a detection module arranged above the illumination module; a dichroic mirror is arranged on one side of the motion control module, and a reflecting mirror is arranged on one side of the dichroic mirror; the illumination module includes a three-dimensional electric moving platform, a metal plane placed on the three-dimensional electric moving platform, and sample particles and a sample solution placed on the metal plane. According to the present invention, it has the advantages of simple system, low cost, easy implementation, small processing difficulty, strong flexibility in optical tweezer capture, and diverse capture functions.

Description

Technical Field

[0001] The present invention relates to the technical field of near-field region optical manipulation, and particularly relates to a device for generating a reconfigurable multi-potential well SPPs vector vortex optical tweezer excited by a single beam of light. Background Art

[0002] Vortex beam optical tweezers carrying orbital angular momentum (OAM) and spatially varying polarization distributions not only cause the trapped particles to rotate (spin and revolve along an orbit), but also can control their rotation direction and speed, bringing rich manipulation methods and effects to the field of optical manipulation of particles. The vector vortex beam array not only has the characteristics of a single-beam optical tweezer, but also adds a new degree of freedom of spatial arrangement, further expanding the potential application value of the vector vortex beam optical tweezer. However, due to the existence of the diffraction limit and the large Brownian motion of nanoparticles in a liquid environment, it is difficult to manipulate nanoparticles with vortex beam optical tweezers in free space to complete the control of complex motion trajectories.

[0003] The excitation methods of SPPs vector vortex optical tweezers are mainly divided into two types: structural regulation method and non-structural regulation method. For the structural regulation method, it mainly utilizes the optical resonance response of structural units, and regulates specially designed structural units according to phase principles such as resonance, propagation, geometry, topology, and multifunctional metasurfaces, confining the optical field energy in a region much smaller than the diffraction limit to form an electromagnetic field hot spot, greatly improving the optical gradient force and capture accuracy. Although this method has high capture ability and accuracy, it has extremely high requirements for processing accuracy. If simultaneous capture of multiple particles with different shapes is to be achieved, it requires the cooperation of multiple microstructural surfaces, resulting in problems such as redundant processing units, high cost, and great difficulty. For the non-structural regulation method, it mainly uses a tightly focused system and a metal plane to jointly complete the process of exciting metal SPPs by an incident beam and focusing to form a near-field optical tweezer. This method can greatly reduce the dependence of the generation of SPPs optical tweezers on surface microstructures, and can directly establish a one-to-one correspondence between the phase and polarization distribution of the incident light and the phase and polarization distribution of the focused optical field, realizing dynamic regulation of multi-dimensional attributes such as the phase, amplitude, and polarization state of the optical field. However, based on existing research, most of them either produce a single SPPs vortex optical tweezer and cannot solve the problem of simultaneous capture and control of multiple particles, or use beam splitting elements or phase regulation elements, which essentially provide a phase regulation method to generate multiple scalar optical tweezers. Although multiple particles can be controlled, it is inadequate in realizing nano-scale particle confinement relying on rich and variable polarization distributions. In addition, based on the phase regulation method, the polarization distribution of the focused optical field is uniform or only partially polarized modulated. In other words, this method cannot solve the problem of generating and modulating vector vortex beam optical tweezers with rich and variable polarization distributions. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a single-beam light-excited reconfigurable multi-potential well SPPs vector vortex optical tweezer generating device, which has a simple system, low cost, easy implementation, low processing difficulty, strong flexibility in optical tweezer capture, and diverse capture functions. To achieve the above object and other advantages of the present invention, there is provided a single-beam light-excited reconfigurable multi-potential well SPPs vector vortex optical tweezer generating device, comprising:

[0005] A light source module, a beam expanding and collimating module disposed on one side of the light source module, an excitation beam generating and excitation light field modulating module disposed on one side of the beam expanding and collimating module, a motion control module disposed on one side of the excitation beam generating and excitation light field modulating module, an illumination module disposed above the motion control module, and a detection module disposed above the illumination module; a dichroic mirror is disposed on one side of the motion control module, and a reflector is disposed on one side of the dichroic mirror;

[0006] The illumination module includes a three-dimensional electric moving platform, a metal plane placed on the three-dimensional electric moving platform, and sample particles and sample solution placed on the metal plane.

[0007] Preferably, the excitation beam generating and excitation light field modulating module includes a beam splitting prism, a 4f system disposed on one side of the beam splitting prism, and a vortex wave plate disposed on one side of the 4f system. The 4f system includes a first focusing lens and a second focusing lens with the same focal length.

[0008] Preferably, a reflective spatial light modulator and a spatial light modulator are disposed above the beam splitting prism.

[0009] Preferably, the motion control module includes a photoelectric sensor, a data analysis terminal signal-connected to the photoelectric sensor, and a focusing lens disposed opposite to the photoelectric sensor, and the focusing lens is disposed opposite to the reflector.

[0010] Preferably, the beam expanding and collimating module includes a first reflector, a first lens disposed opposite to the first reflector, and a second lens disposed opposite to the first lens. The first reflector is located above the light source module, and the second lens is disposed opposite to the beam splitting prism.

[0011] A method for generating a single-beam light-excited reconfigurable multi-potential well SPPs vector vortex optical tweezer includes the following steps:

[0012] The light source module emits an excitation light source onto the beam expanding and collimating module. The beam is expanded by the beam expanding and collimating module. The beam reaches the beam splitting prism for splitting. One beam reaches the reflective spatial light modulator for loading encoded information to obtain a loaded encoded information beam. The loaded encoded information beam converges with the other beam and reaches the dichroic mirror via the 4f system and the vortex wave plate.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: Based on the total internal reflection structure and the waveguide structure, near-field particle capture and control are realized, and the state of the captured particles is regulated by parameters such as the structural size or the incident laser power. However, the control method is not flexible enough. The present invention utilizes the surface plasmon resonance effect generated by the coupling of free electrons on the metal surface and incident photons, with a higher surface electric field intensity gradient and stronger localization of particles in the near-field region. The prior art for realizing near-field optical manipulation technology based on the SPPs resonance effect mainly adopts the precise design of the metasurface structure, which has high requirements for processing accuracy, and the static structure of the device cannot be actively tuned. The present invention uses a metal plane combined with a tightly focused system. Based on the incidence of a single beam, the same effect can be achieved, generating a reconfigurable multi-well SPPs vortex optical tweezer carrying different orders, and each optical tweezer property can be dynamically modulated, with advantages such as real-time reconstruction of light waves, simple structure, low processing cost, and easy processing. The multi-well SPPs vortex optical tweezers of different orders have complex polarization and phase distributions with spatial variations, and their generation and dynamic modulation in the near-field region are a huge challenge. The present invention can generate this optical tweezer array based only on a non-structure-dependent single-layer metal plane, and the number, position, energy, and polarization distribution thereof can be dynamically modulated, having great advantages in terms of processing cost, system structure, processing difficulty, flexibility of optical tweezer capture, and diversity of capture functions. Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of a device for generating a reconfigurable multi-well SPPs vector vortex optical tweezer excited by a single beam of light according to the present invention. Detailed Embodiments

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0016] Refer to Figure 1, A device for generating a reconfigurable multi-potential well SPPs vector vortex optical tweezer excited by a single beam of light, comprising: a source module 1, a beam expanding and collimating module 2 disposed on one side of the light source module 1, an excitation beam generating and excitation light field modulating module 3 disposed on one side of the beam expanding and collimating module 2, a motion control module 4 disposed on one side of the excitation beam generating and excitation light field modulating module 3, an illumination module 5 disposed above the motion control module 4, and a detection module 6 disposed above the illumination module 5; a dichroic mirror 7 is disposed on one side of the motion control module 4, and a reflector 8 is disposed on one side of the dichroic mirror 7; the excitation beam generating and excitation light field modulating module 3 includes a beam splitting prism 3-1, a set of equi-focal length focusing lenses 3-2 and 3-3 disposed on one side of the beam splitting prism 3-1, and a vortex wave plate 3-6 disposed on one side of the set of equi-focal length focusing lenses 3-2 and 3-3. The 4f system includes a first focusing lens 3-2 and a second focusing lens 3-3 with the same focal length. A reflective spatial light modulator 3-4 and a spatial light modulator 3-5 are disposed above the beam splitting prism 3-1. The source module 1 generates an excitation light source with good beam quality, good monochromaticity, and stability. The beam expanding and collimating module 2 expands the beam. The excitation beam generating and excitation light field modulating module 3 generates a vector vortex beam carrying an arbitrary polarization distribution. By loading the mode extraction technology and the optical pen technology through the reflective spatial light modulator 3-4, the phase information of the incident vector vortex beam is modulated to generate a multi-potential well SPPs vector vortex optical tweezer, and the attributes of the number, intensity, position, and polarization distribution of the excitation optical tweezer are modulated. The motion control module 4 controls the displacement of the three-dimensional electric moving platform 5-2 carrying the sample. The illumination module 5 irradiates the sample, loads the SPPs optical tweezer capture information, and the detection module 6 collects the behavior information of the sample and transmits it back to the data analysis terminal 4-2.

[0017] The illumination module 5 includes a three-dimensional electric moving platform 5-2, a metal plane 10 placed on the three-dimensional electric moving platform 5-2, and a sample particle 9 and a sample solution 11 placed on the metal plane 10.

[0018] Further, the motion control module 4 includes a photoelectric sensor 4-1, a data analysis terminal 4-2 signal-connected to the photoelectric sensor 4-1, and a focusing lens 4-3 disposed opposite to the photoelectric sensor 4-1, and the focusing lens 4-3 is disposed opposite to the reflector 8.

[0019] Further, the beam expanding and collimating module 2 includes a first reflector 2-1, a first lens 2-2 disposed opposite to the first reflector 2-1, and a second lens 2-3 disposed opposite to the first lens 2-2. The first reflector 2-1 is located above the light source module 1, and the second lens 2-3 is disposed opposite to the beam splitting prism 3-1. The beam expanding and collimating module 2 expands and collimates the beam to obtain parallel light, achieving the purpose of improving the beam quality.

[0020] The "Optical Pen" modulation phase and the mode extraction phase act together to modulate the incident laser beam to generate a multi-well SPPs vector vortex optical tweezer and achieve reconfigurable and dynamic optical field modulation. The specific modulation process is as follows:

[0021] First, if the reflective spatial light modulator 3-4 does not load the "Optical Pen" modulation phase and the mode extraction phase formula 3-5, the linearly polarized light emitted by the light source module 1 passes through the beam expander and collimator module 2, the polarization beam splitter prism 3-1, and the 4f system composed of the same focal length focusing lenses 3-2 and 3-3 to reach the vortex wave plate 3-6. After the light beam passes through the vortex wave plate 3-6, it is converted from a linearly polarized light beam to a high-order vector vortex beam (Vector Vortex Beams, VVBs). Subsequently, the reflective spatial light modulator 3-4 loads the "Optical Pen" modulation phase and the mode extraction phase 3-5 to act on the generated high-order VVB laser beam, and the modulated light beam is focused by the objective lens 4-3. The modulation phase 3-5 is located at the entrance pupil plane of the objective lens 4-3. According to the Debye vector diffraction theory, the electric field in the focusing region of the objective lens 4-3 is expressed as:

[0022] ;

[0023] where A is the normalization constant; θ and φ are the convergence angle and the azimuth angle respectively;

[0024] , where NA is the numerical aperture of the objective lens 4-3 and n is the refractive index in the focusing space; the wave number , where λ is the wavelength of the incident VVB; represents the position vector of any point in the focal region . The unit vector represents the direction of the wave vector. The electric field amplitude of the incident VVB can be expressed as (2)

[0025] where, is the ratio of the pupil radius to the waist of the incident light beam. The V in formula (1) represents the propagation unit vector of the light beam after passing through the objective lens 4-3. Usually, the electric field of the incident m-order VVB is expressed as , and represent the x and y polarization components of the VVB respectively. Therefore, , where and are respectively and electric vectors, expressed as the electric vectors of, expressed as

[0026] ;

[0027] ;

[0028] Where t represents the matrix transpose operator.

[0029] In formula (1), , is the modulation phase and mode extraction phase formula 3-5 of "Optical Pen", and also the modulation phase of the m-th order VVB. The "Optical Pen" modulation phase formula is , where xj, yj, and zj are used for the dynamic regulation of the position of the j-th SPPs vector vortex optical tweezer, the maximum value of j corresponds to the total number of focal points N in the "Optical Pen" modulation phase formula, and sj and δj are used for the amplitude and phase modulation of the j-th optical tweezer; the mode extraction phase is used for the polarization mode modulation of the optical tweezer, and the corresponding modulation factor is .

[0030] For the multi-well SPPs vector vortex optical tweezer containing integer and fractional orders, the integer and fractional order VVB electric field expressions are introduced as . When the parameter l + 0.5 = 0 and M is an integer, integer-order SPPs vector vortex optical tweezers are generated; when l + 0.5 is a fraction and M is also a fraction, fractional-order SPPs vector vortex optical tweezers are generated; if integer-order SPPs vector vortex optical tweezers are extracted, the mode extraction phase modulation factor is , and for fractional-order SPPs vector vortex optical tweezers, the mode extraction phase modulation factor .

[0031] After the modulation phase modulation, the beam passes through the dichroic mirror 7. One part reaches the objective lens 4-3, and the other part reaches the high numerical aperture objective lens 5-1 and the metal structure carried by the motorized displacement stage 5-2 to act. When the resonance condition is met, that is, the resonance angle is about 43°, the incident high-order VVB can excite an annular focusing ring on the metal plane. Combining the "Optical Pen" and the mode extraction modulation phase, finally, can be used to obtain integer-order and fractional-order multi-well SPPs vector vortex optical tweezers on the metal surface, and their quantity, position, and intensity can be modulated in real time and dynamically.

[0032] The excitation beam is a high-order vector vortex beam, expressed as , where \(e_r\) and \(e_{\varphi}\) are the radial and angular unit vectors. By using the mode extraction phase to modulate the incident high-order vector vortex beam, multiple SPPs vector vortex optical tweezer beams can be simultaneously extracted from a single incident beam. The modulation process is achieved when the focusing lens 5-1 has a high numerical aperture and interacts with the metal plane 10 under resonance conditions. The high numerical aperture focusing lens 5-1 is an immersion objective with a numerical aperture NA = 1.49; the metal plane 10 is a gold-plated metal plane with a refractive index of 0.54386 + 2.2309i; the resonance condition is the incident angle of the incident light when an obvious resonance ring appears on the metal plane, also called the resonance angle, which is approximately 43°.

[0033] A method for generating a reconfigurable multi-potential well SPPs vector vortex optical tweezer excited by a single beam of light includes the following steps:

[0034] The light source module 1 includes a laser light source 1-1 and a polarizer 1-2 to generate a linearly polarized light beam, which is excited to the beam expanding and collimating module 2. The beam is expanded by the beam expanding and collimating module 2, and this beam reaches the beam splitting prism 3-1 for beam splitting. One beam of light reaches the reflective spatial light modulator 3-4 to load phase encoding information to obtain a loaded encoding information beam. This loaded encoding information beam converges with another beam of light, and then passes through a 4f system composed of a first focusing lens 3-2 and a first focusing lens 3-3 with the same focal length and a vortex wave plate 3-6 to be converted into high-order VVBs. The high-order VVBs are transmitted to the entrance pupil section of the high-power objective lens 5-1, and are focused and coupled by the high-power objective lens 5-1 to excite the SPPs field on the metal plane 10, generating a multi-potential well SPPs vector vortex optical tweezer. The metal plane 10 is located in the glass sealed chamber 5-3, and the sealed chamber 5-3 is fixed by a three-dimensional electric moving fixture 5-2. The glass sealed chamber 5-3 includes the metal plane 10, the sample 9 on the metal plane 10, and the solvent 11 that submerges the sample 9. The distance between the high-power objective lens 5-1 and the glass sealed chamber 5-3 is filled with oil 5-4.

[0035] After the white light source is expanded by the diaphragm 6-3 and the beam expanding and collimating system composed of the lenses 6-1 and 6-2, it irradiates the surface of the sample, illuminating the sample so that it can be directly imaged by the optoelectronic sensor device 4-1. Through the two-dimensional movement of the chamber fixed by the three-dimensional electric moving fixture 5-2, an annular SPPs field is excited and generated on the metal plane 10. Under the action of the light field modulation module 3, multiple SPPs vector vortex optical tweezers are generated at the center of the SPPs field, corresponding to the multi-potential well SPPs vector vortex optical tweezer. The optical tweezer, as a highly focused light source, is coupled with the sample 9 on the metal plane 10 to control the behavior of the sample 9. The behavior information can be directly collected and imaged by the optoelectronic sensor device 4-1 and transmitted back to the data analysis terminal 4-2 to complete the construction and performance verification of the multi-probe SPPs vector optical tweezer system.

[0036] The number of devices and the processing scale described herein are used to simplify the description of the present invention, and the application, modification, and variation of the present invention will be obvious to those skilled in the art.

[0037] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated examples described herein.

Claims

1. A device for generating a reconfigurable multi-potential well SPPs vector vortex optical tweezer excited by a single beam of light, Characterized in that, Comprising: A light source module (1), a beam expanding and collimating module (2) arranged on one side of the light source module (1), an excitation beam generating and excitation light field modulating module (3) arranged on one side of the beam expanding and collimating module (2), a motion control module (4) arranged on one side of the excitation beam generating and excitation light field modulating module (3), an illumination module (5) arranged above the motion control module (4), and a detection module (6) arranged above the illumination module (5); A dichroic mirror (7) is arranged on one side of the motion control module (4), and a reflecting mirror (8) is arranged on one side of the dichroic mirror (7); The excitation beam generating and excitation light field modulating module (3) includes a beam splitting prism (3-1), a 4f system arranged on one side of the beam splitting prism (3-1), and a vortex wave plate (3-6) arranged on one side of the 4f system. The 4f system includes a first focusing lens (3-2) and a second focusing lens (3-3) with the same focal length; The illumination module (5) includes a three-dimensional electric moving platform (5-2), a metal plane (10) placed on the three-dimensional electric moving platform (5-2), and a sample particle (9) and a sample solution (11) placed on the metal plane (10); A reflective spatial light modulator (3-4) and a spatial light modulator (3-5) are arranged above the beam splitting prism (3-1).

2. A device for generating a reconfigurable multi-potential well SPPs vector vortex optical tweezer excited by a single beam of light as described in claim 1, Characterized in that, The motion control module (4) includes a photoelectric sensor (4-1), a data analysis terminal (4-2) signal-connected to the photoelectric sensor (4-1), and a focusing lens (4-3) arranged opposite to the photoelectric sensor (4-1), and the focusing lens (4-3) is arranged opposite to the reflecting mirror (8).

3. A device for generating a reconfigurable multi-potential well SPPs vector vortex optical tweezer excited by a single beam of light as described in claim 2, Characterized in that, The beam expanding and collimating module (2) includes a first reflecting mirror (2-1), a first lens (2-2) arranged opposite to the first reflecting mirror (2-1), and a second lens (2-3) arranged opposite to the first lens (2-2). The first reflecting mirror (2-1) is located above the light source module (1), and the second lens (2-3) is arranged opposite to the beam splitting prism (3-1).

4. A device for generating a reconfigurable multi-potential well SPPs vector vortex optical tweezer excited by a single beam of light as described in claim 1, Characterized in that, Comprising the following steps: The light source module (1) emits an excitation light source to the beam expanding and collimating module (2), the beam is expanded by the beam expanding and collimating module (2), and the beam reaches the beam splitting prism (3-1) for beam splitting. One beam of light reaches the reflective spatial light modulator (3-4) to load encoded information to obtain a loaded encoded information beam. The loaded encoded information beam converges with the other beam of light and reaches the dichroic mirror (7) via the 4f system and the vortex wave plate (3-6).

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