A device for realizing particle light leakage switch using correlated vortex array

Abstract

The present invention discloses a device for controlling the light leakage switch of particles by using an associated vortex array. The implementation steps are: prepare a set of hologram sequences by computer and load them into a spatial light modulator to play repeatedly in the form of dynamic frames; irradiate the spatial light modulator with a laser, and make the light beam vertically upward after reflection, that is, opposite to the direction of the gravity field; select the first-order diffraction light of the reflected light beam and irradiate it into a 10x objective lens to focus to form a light trap; put the particles into the light trap, and the state of the particles is determined by the phase and coherence of the associated vortex light beam modulated by the spatial light modulator; prepare different hologram sequences by changing parameters and load them into the spatial light modulator to play in the form of dynamic frames to achieve the control of the up and down movement and rotation of the particles. The device provided by the present invention uses a small number of optical devices and a simple layout, and belongs to the field of optical manipulation.

Description

Technical Field

[0001] The present invention provides a device for realizing a particle light leakage switch by using a correlation vortex array. The correlation vortex generated by the device is adjustable, and can realize the upward and downward movement and rotation of the particles, and belongs to the field of optical particle control. Background Art

[0002] The photons in the vortex beam can carry both orbital angular momentum (related to the vortex phase) and spin angular momentum (related to the polarization state). The focused light trap can exchange momentum and angular momentum with the particles, which is one of the most promising means to manipulate the translation and rotation of particles. In recent years, the real-time dynamic manipulation of particles using vortex light has received more and more attention.

[0003] A coherent vortex is a special type of optical vortex that has a spiral phase structure in the two-point cross-spectral density function. The two-point correlation function is related to the coherence of light, so it is called a coherent vortex. Coherent vortices are less affected than optical vortices when propagating through obstacles in turbulence, so they are used in target recognition and imaging, optical manipulation, and self-reconstruction in obstacle imaging.

[0004] The literature [MIN-JIE LIU, JUN CHEN, YANG ZHANG, YAN SHI, CHUN-LIU ZHAO, AND SHANG-ZHONG JIN, "Generation of coherence vortex by modulating the correlation structure of random lights", Photon. Res. 7, 1485-1492 (2019), doi: 10.1364 / PRJ.7.001485] reported a method of generating correlation vortex using digital technology. However, the manipulation of the rotation and up and down movement of particles by using the correlation vortex beam is a problem that has not yet been realized. Summary of the invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a device for realizing a particle light leakage switch using a correlated vortex array. The device provided by the present invention directly realizes the rotation and up and down movement of particles through the regulation of digital technology. By controlling the parameters on the hologram, the particles can be rotated clockwise or counterclockwise. By adjusting the size of the coherence, the particles can be moved up and down. The device used by the present invention has few optical devices and a simple layout.

[0006] The technical solution to achieve the purpose of the invention is to provide a device for realizing a particle light leakage switch using a correlated vortex array, comprising the following steps:

[0007] (1) A computer generates a special digital hologram; the digital hologram can generate a superposition state light field in the following form:

[0008]

[0009] It means that the light field generated by the kth hologram is formed by a radial array of N sub-light sources in M ​​coherent superposition fields, where N = 5; δ p Indicates random phase, ranging from 0 to 2π;

[0010]

[0011] represents the light field of the jth sub-light source, is the initial phase of the light field of the sub-light source, α j is the azimuth of the sub-light source, 0≤L0 <N; represents the amplitude of the j-th sub-light source light field, (a j ,b j ) is the position of the sub-light source in the radial array, Indicates the position of the disturbance center; the disturbance center is uniformly and randomly distributed within a circle with a radius of c0; in the program for preparing the hologram, the above parameters L0 and c0 are modified to prepare different hologram groups, and each group of holograms is loaded onto the spatial light modulator and dynamically played at a certain frequency, so that the laser beam can be modulated to generate a correlated vortex beam with certain characteristics to achieve the effect of light leakage and light opening;

[0012] (2) connecting a computer to a spatial light modulator; loading a hologram sequence into the spatial light modulator and repeatedly playing the hologram sequence on a liquid crystal screen in the form of dynamic frames;

[0013] (3) turning on the laser to generate linearly polarized light with a stable wavelength, adjusting the polarization plane of the laser output light to match that of the spatial light modulator; and injecting the output light beam of the laser into a beam expander for beam expansion;

[0014] (4) injecting the expanded light beam into the liquid crystal screen of the spatial light modulator, adjusting the angle of the liquid crystal screen of the spatial light modulator so that the modulated light beam is reflected vertically upward by the liquid crystal screen; using a pinhole diaphragm to select the first-order diffraction light, and irradiating the first-order diffraction light into a 10x objective lens to focus and generate a light trap; the vertical upward direction is the opposite direction of the gravity field;

[0015] (5) placing the particle in a light trap, the particle is subjected to the vertical upward force from the light beam and its own gravity, and its state is determined by the phase and coherence of the associated vortex light beam modulated by the spatial light modulator, and the phase and coherence can be adjusted by parameters L0 and c0 respectively;

[0016] (6) The particles at the center of the associated vortex beam will not change their motion state due to the phase influence; only when the initial position of the particles is not at the center of the beam will the particles be guided by the light to rotate; when L0=1, 2, the generated associated vortex guides the particles to rotate clockwise, and the state L0=2 rotates faster than the state L0=1; when L0=3, 4, the generated associated vortex guides the particles to rotate counterclockwise, and the state L0=4 rotates faster than the state L0=3; the light force felt by the particles at the non-center position is asymmetric in the horizontal direction, which makes the particles move toward the center of the beam, thus forming a particle light funnel;

[0017] (7) When c0 increases, the coherence of the associated vortex light beam decreases, the central light intensity increases, and the particles at the center position move upward under the action of the light field; when c0 decreases, the coherence of the associated vortex light beam increases, the central light intensity decreases, and the particles at the center position move downward under the action of gravity; when L0 = 0 and 5, the radial array composed of five sub-light sources cannot form vortex light, and the particle light funnel disappears.

[0018] The beneficial effects of the present invention are:

[0019] 1. The present invention proposes a device for realizing a particle light leakage switch by using a correlated vortex array. The device proposed by the present invention can control the rotation and up and down movement of particles through correlated vortices.

[0020] 2. The device used in the present invention has a simple optical path and fewer optical devices.

[0021] 3. The present invention adopts a fully digital method to generate correlated vortex light beams, the light source correlation structure is adjustable, and there will be no mutual interference between the regulated modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of a device for realizing a particle light leakage switch by using a correlated vortex array provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with examples. The following examples are explanations of the present invention and are also preferred application forms of the present invention, but the present invention is not limited to the following examples.

[0024] like Figure 1 As shown, it is a structural schematic diagram of a particle light leakage switch device using a correlated vortex array provided in this embodiment: it includes a laser 1; a beam expander 2; a spatial light modulator 3; a computer 4; a pinhole diaphragm 5; and a 10x objective lens 6.

[0025] In this embodiment, the light field used to generate the associated vortex array is:

[0026]

[0027] It means that the light field generated by the kth hologram is formed by a radial array of N sub-light sources in M ​​coherent superposition fields, where N = 5; δ p Indicates random phase, ranging from 0 to 2π; represents the light field of the jth sub-light source, is the initial phase of the light field of the sub-light source, α j is the azimuth of the sub-light source, 0≤L0 <N; represents the amplitude of the j-th sub-light source light field, (a j ,b j ) is the position of the sub-light source in the radial array, Indicates the position of the disturbance center; the disturbance center is uniformly and randomly distributed within a circle with a radius of c0; in the program for preparing the hologram, the above parameters L0 and c0 are modified to prepare different hologram groups, and each group of holograms is loaded onto the spatial light modulator 3 and dynamically played at a certain frequency, so that the laser beam can be modulated to generate a correlated vortex beam with certain characteristics to achieve the effect of light leakage and light opening; the computer 4 is connected to the spatial light modulator 3; the hologram sequence is loaded into the spatial light modulator 3, and repeatedly played on the liquid crystal screen in the form of dynamic frames; the laser 1 is turned on to generate linearly polarized light with stable wavelength, and the polarization plane of the light emitted by the laser 1 is adjusted to be aligned with the spatial light modulator 3 Matching; inject the outgoing light beam of the laser 1 into the beam expander 2 for beam expansion; inject the expanded light beam into the liquid crystal screen of the spatial light modulator 3, adjust the angle of the liquid crystal screen of the spatial light modulator 3, so that the modulated light beam is reflected vertically upward by the liquid crystal screen; use the pinhole aperture 5 to select the first-order diffraction light, and irradiate this first-order diffraction light into the 10x objective lens 6 for focusing to generate a light trap; the vertical upward direction is the opposite direction of the gravity field; put the particle into the light trap, the particle is subjected to the vertical upward force from the light beam and its own gravity, and its state is determined by the phase and coherence of the associated vortex light beam modulated by the spatial light modulator 3, and the phase and coherence can be adjusted by parameters L0 and c0 respectively;

[0028] In this embodiment, the particles at the center of the associated vortex light beam will not change their motion state due to the influence of the phase; only when the initial position of the particles is not at the center of the light beam, the particles will be guided by the light to rotate; when L0=1, 2, the generated associated vortex guides the particles to rotate clockwise, and the state L0=2 rotates faster than the state L0=1; when L0=3, 4, the generated associated vortex guides the particles to rotate counterclockwise, and the state L0=4 rotates faster than the state L0=3; the light force felt by the particles at the non-center position is asymmetric in the horizontal direction, which makes the particles move toward the center of the light beam, thereby forming a particle light funnel; when c0 increases, the coherence of the associated vortex light beam decreases, the central light intensity increases, and the particles at the center position move upward under the action of the light field; when c0 decreases, the coherence of the associated vortex light beam increases, the central light intensity decreases, and the particles at the center position move downward under the action of gravity; when L0=0 and 5, the radial array composed of five sub-light sources cannot form vortex light, and the particle light funnel disappears.

Claims

1. A device for realizing a particle light leakage switch using a correlated vortex array, comprising a laser (1), a beam expander (2), a spatial light modulator (3), a computer (4), a pinhole diaphragm (5), and a 10x objective lens (6); characterized in that: (A) indicates that the light field generated by the kth hologram is formed by a radial array of N sub-light sources in M ​​coherent superposition fields. Here, N=5; δ p Indicates random phase, ranging from 0 to 2π; represents the light field of the jth sub-light source, is the initial phase of the light field of the sub-light source, α j is the azimuth of the sub-light source, 0≤L0 <N; represents the amplitude of the j-th sub-light source light field, (a j ,b j ) is the position of the sub-light source in the radial array, Indicates the position of the disturbance center; the disturbance center is uniformly and randomly distributed within a circle with a radius of c0; in a program for preparing a hologram, the above parameters L0 and c0 are modified to prepare different hologram groups, and each group of holograms is loaded onto a spatial light modulator (3) and dynamically played at a certain frequency, so that the laser beam can be modulated to generate a correlated vortex beam with certain characteristics, so as to achieve the effect of light leakage and light opening; (B) connecting a computer (4) to a spatial light modulator (3); loading a hologram sequence into the spatial light modulator (3), and repeatedly playing the hologram sequence on a liquid crystal screen in the form of dynamic frames; Turning on the laser (1) to generate linearly polarized light with a stable wavelength, adjusting the polarization plane of the output light of the laser (1) to match that of the spatial light modulator (3); injecting the output light beam of the laser (1) into a beam expander (2) for beam expansion; injecting the beam after beam expansion into a liquid crystal screen of the spatial light modulator (3), and adjusting the angle of the liquid crystal screen of the spatial light modulator (3) so that the modulated light beam is reflected vertically upward by the liquid crystal screen; (C) using a pinhole aperture (5) to select first-order diffraction light, and irradiating the first-order diffraction light into a 10x objective lens (6) to focus and generate a light trap; the vertical upward direction is the opposite direction of the gravitational field; placing the particle in the light trap, the particle is subjected to the vertical upward force from the light beam and its own gravity, and its state is determined by the phase and coherence of the associated vortex light beam modulated by the spatial light modulator (3), and the phase and coherence can be adjusted by parameters L0 and c0 respectively; (D) The particles at the center of the associated vortex beam will not change their motion state due to the influence of the phase; only when the initial position of the particles is not at the center of the beam will the particles be guided by light to rotate; when L0=1, 2, the generated associated vortex guides the particles to rotate clockwise, and the state L0=2 rotates faster than the state L0=1; when L0=3, 4, the generated associated vortex guides the particles to rotate counterclockwise, and the state L0=4 rotates faster than the state L0=3; the light force felt by the particles at the non-center position is asymmetric in the horizontal direction, which makes the particles move toward the center of the beam, thereby forming a particle light funnel; when c0 increases, the coherence of the associated vortex beam decreases, the central light intensity increases, and the particles at the center move upward under the action of the light field; when c0 decreases, the coherence of the associated vortex beam increases, the central light intensity decreases, and the particles at the center move downward under the action of gravity; when L0=0 and 5, the radial array composed of five sub-light sources cannot form vortex light, and the particle light funnel disappears; (E) the random phases of the holograms repeatedly generated by the computer (4) are independent of each other; (F) The 10x objective lens (6) must be placed in the far field to form a vortex beam, and the distance is 10 times the Rayleigh distance.

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