1. A method of producing a highly controllable off-axis optical bottle, comprising the steps of:

simulating the interference of plane waves and circular Pierce Gaussian beams by using a computer to obtain a phase hologram, and loading the phase hologram to the reflective spatial light modulator S1;

drawing a composite second-order chirped vortex phase on a computer according to the optical parameters, and loading the composite second-order chirped vortex phase on a transmission-type spatial light modulator S2;

illuminating the reflective spatial light modulator S1 with a Gaussian beam to make the reflected light pass through a spatial filtering system, and selecting a positive level stripe in the spatial filtering system to obtain a circular Pierce Gaussian beam;

the round Pierce Gaussian beam passes through the transmission-type spatial light modulator S2 to obtain the round Pierce Gaussian beam modulated by the composite second-order chirp vortex phase, and the round Pierce Gaussian beam is transmitted in vacuum or interference-free air, so that multiple times of strong focusing can be formed in the transmission process, and the off-axis optical bottle is formed.

2. The method of producing a highly controllable off-axis optical bottle according to claim 1, wherein the specific modulation of the circular pierce gaussian beam is:

the analytic formula of the circular Pierce Gaussian beam in the initial plane is as follows:wherein the content of the first and second substances, defined as the Pears integral, x₀As a scaling factor of the content dimension, w₀Is a gaussian beam width; the interference between the circular Pierce Gaussian beam and the plane wave is simulated in the computer to obtain a phase hologram, the phase hologram is loaded on the reflective spatial light modulator S1 and is irradiated by the Gaussian beam, and the emergent light filtered by the spatial filtering system is the circular Pierce Gaussian beam.

3. The method of claim 1, wherein the round pierce gaussian beam is phase modulated by a complex second-order chirped vortex, specifically:

the analytical expression of the composite second-order chirped vortex phase is as follows:wherein, c_iIs a second order chirp factor,/_iIs the vortex order, (x)_i,y_i) For the displacement factor, N is the number of second order chirped vortex phases, and (x)_i,y_i) The conditions are satisfied: x is the number of_i＝c₁x₁/c_i,y_i＝c₁y₁/c_i(ii) a The analytic expression of the round pierce gaussian beam after passing through the transmissive spatial light modulator S2 is:in mathematics, the propagation characteristics of a composite second-order chirped vortex phase modulated circular pierce gaussian beam in free space can be expressed by paraxial wave equations expressed in cylindrical coordinates: is the wavenumber, λ is the wavelength; and drawing a composite second-order chirped vortex phase on a computer, loading the composite second-order chirped vortex phase on the transmission-type spatial light modulator S2, and enabling a round Pierce Gaussian beam to be incident, wherein emergent light is the round Pierce Gaussian beam modulated by the composite second-order chirped vortex phase.

4. The method of claim 1, wherein the position, shape and number of the off-axis optical bottles can be continuously controlled by adjusting the parameters of the initial light field and changing the phase of the composite second-order chirped vortex on the transmissive spatial light modulator S2:

vortex factor l_i: adjusting the size of the mouth or bottom of each optical bottle_iThe larger the bottle mouth, the wider the resulting optical bottle;

chirp displacement factor (x)_i,y_i): adjusting the degree of the off-axis light beam deviating from the optical axis so as to control the position of the off-axis optical bottle in space; if it is(x_i,y_i) (0,0), then the optical bottle is generated on the optical axis, being an on-axis optical bottle;

second order chirp factor c_i: adjusting the distance between the bottle mouth and the bottle bottom of the off-axis optical bottle and the initial plane and the length of each off-axis optical bottle;

number of second-order chirped vortex phases N: adjusting the number of off-axis optical bottles, when there are N chirped phase factors, then N-1 optical bottles can be produced.

5. The method of producing a highly controllable off-axis optical bottle of claim 1, wherein the spatial filtering system comprises lens L1, a diaphragm, and lens L2; the input light field is subjected to Fourier transform through a lens L1 to obtain a frequency spectrum surface, the diaphragm is used for selecting a positive first-order interference fringe in the frequency spectrum surface, and the output light field, namely a round Pierce Gaussian beam, is obtained through inverse Fourier transform through a lens L2.

6. A system for producing a highly controllable off-axis optical bottle, comprising:

the computer is used for simulating the interference of the plane wave and the circular Pierce Gaussian beam to obtain a phase hologram, and loading the phase hologram to the reflective spatial light modulator S1; drawing a composite second-order chirped vortex phase according to the optical parameters, and loading the composite second-order chirped vortex phase onto a transmission-type spatial light modulator S2;

a laser for generating a gaussian beam;

a reflective spatial light modulator S1 arranged on the transmission path of the Gaussian beam for loading a phase hologram;

the spatial filtering system is used for receiving the light beam reflected by the reflective spatial light modulator S1, selecting the positive-level stripe of the frequency spectrum surface of the input light field, and obtaining the circular Pierce Gaussian beam at the outlet focal plane of the spatial filtering system;

the transmission type spatial light modulator S2 is arranged at an outlet focal plane of the spatial filtering system and used for loading the composite second-order chirped vortex phase; amplitude and phase modulation can be carried out simultaneously, according to the composite second-order chirped vortex phase and the round Pierce Gaussian beam, the round Pierce Gaussian beam modulated by the composite second-order chirped vortex phase is obtained and is transmitted in vacuum or interference-free air, and multiple times of strong focusing can be formed in the transmission process, so that an off-axis optical bottle is formed;

and the beam quality analyzer is arranged behind the transmission-type spatial light modulator S2 and is used for collecting beam cross section information.

7. The system for generating the high-controllability off-axis optical bottle as claimed in claim 6, further comprising a beam expander disposed at the exit of the laser for expanding the gaussian beam into an approximately plane wave.

8. The system for generating the high-controllability off-axis optical bottle as claimed in claim 7, further comprising a non-polarizing beam splitter disposed between the beam expander and the reflective spatial light modulator S1 for splitting the expanded gaussian beam; a portion of the light propagates after being transmitted to the reflective spatial light modulator S1.

9. The system for creating a highly controllable off-axis optical bottle of claim 6, wherein the spatial filtering system comprises lens L1, a diaphragm, and lens L2; the input light field is subjected to Fourier transform through a lens L1 to obtain a frequency spectrum surface, the diaphragm is used for selecting a positive first-order interference fringe in the frequency spectrum surface, and the output light field, namely a round Pierce Gaussian beam, is obtained through inverse Fourier transform through a lens L2.

10. The system for producing a highly controllable off-axis optical bottle according to claim 8, wherein said laser is a he — ne laser producing a gaussian beam wavelength of 632.8 nm; the non-polarization beam splitter has a splitting ratio of 1: 1, a non-polarizing beam splitter; the resolution of the beam quality analyzer is 2400 multiplied by 2400, and the beam quality analyzer is used for acquiring the light intensity distribution of the cross section of the light beam; the reflective spatial light modulator S1, the non-polarizing beam splitter, the spatial filtering system and the transmissive spatial light modulator S2 are arranged on the same axis; the laser, the beam expander and the non-polarization beam splitter are arranged on the same axis.

Background

By "light bottle" is meant a closed dark space structure formed by a three-dimensional light beam during propagation. This concept was proposed in 2000 by j.arlt et al, and the optical vial is of interest because of its unique structure, allowing manipulation of multiple particles, as compared to optical tweezers previously proposed in 1986 by a.ashkin et al, which are only capable of manipulation of a single particle.

In addition, in 2018, x.y.chen et al proposed a round pierce beam. The derivative light beam of the Pierce light beam inherits the self-healing characteristic of the Pierce light beam and has stronger focusing capacity. More importantly, compared with the round Airy beam, the round Pierce beam cannot vibrate after being focused. These properties make it of great potential in the field of optical micromanipulation.

Based on the broad application prospect of "optical bottles", experts in many optical fields try to produce optical bottles in different ways, besides traditional phase modulation, self-imaging, moire fringe, fourier space generation, etc. are currently available. However, in the prior art, most of the generated light bottles are single along-axis light bottles, that is, the light bottles are generated on the optical axis, and even if the light bottles are off-axis, the problem that the light bottles are less in off-axis degree and less in adjustable parameters exists, thereby bringing certain difficulties to the application.

Disclosure of Invention

Accordingly, in order to solve the above-mentioned problems of the prior art, the present invention provides a method and system for producing a highly controllable off-axis optical bottle, which is more efficient in particle capture and manipulation and has a high degree of freedom.

The invention solves the problems through the following technical means:

in one aspect, the present invention provides a method for producing a highly controllable off-axis optical bottle, comprising the steps of:

simulating the interference of plane waves and circular Pierce Gaussian beams by using a computer to obtain a phase hologram, and loading the phase hologram to the reflective spatial light modulator S1;

drawing a composite second-order chirped vortex phase on a computer according to the optical parameters, and loading the composite second-order chirped vortex phase on a transmission-type spatial light modulator S2;

illuminating the reflective spatial light modulator S1 with a Gaussian beam to make the reflected light pass through a spatial filtering system, and selecting a positive level stripe in the spatial filtering system to obtain a circular Pierce Gaussian beam;

the round Pierce Gaussian beam passes through the transmission-type spatial light modulator S2 to obtain the round Pierce Gaussian beam modulated by the composite second-order chirp vortex phase, and the round Pierce Gaussian beam is transmitted in vacuum or interference-free air, so that multiple times of strong focusing can be formed in the transmission process, and the off-axis optical bottle is formed.

Further, the specific modulation of the circular pierce gaussian beam is:

the analytic formula of the circular Pierce Gaussian beam in the initial plane is as follows:

wherein the content of the first and second substances,

defined as the Pears integral, x₀As a scaling factor of the content dimension, w₀Is a gaussian beam width; the interference between the circular Pierce Gaussian beam and the plane wave is simulated in the computer to obtain a phase hologram, the phase hologram is loaded on the reflective spatial light modulator S1 and is irradiated by the Gaussian beam, and the emergent light filtered by the spatial filtering system is the circular Pierce Gaussian beam.

Further, the phase modulation of the circular pierce gaussian beam by the composite second-order chirped vortex specifically comprises:

the analytical expression of the composite second-order chirped vortex phase is as follows:

wherein the content of the first and second substances,

c_iis a second order chirp factor,/_iIs the vortex order, (x)_i,y_i) For the displacement factor, N is the number of second order chirped vortex phases, and (x)_i,y_i) The conditions are satisfied: x is the number of_i＝c₁x₁/c_i,y_i＝c₁y₁/c_i(ii) a The analytic expression of the round pierce gaussian beam after passing through the transmissive spatial light modulator S2 is:in mathematics, the propagation characteristics of a composite second-order chirped vortex phase modulated circular pierce gaussian beam in free space can be expressed by paraxial wave equations expressed in cylindrical coordinates:

is the wavenumber, λ is the wavelength; and drawing a composite second-order chirped vortex phase on a computer, loading the composite second-order chirped vortex phase on the transmission-type spatial light modulator S2, and enabling a round Pierce Gaussian beam to be incident, wherein emergent light is the round Pierce Gaussian beam modulated by the composite second-order chirped vortex phase.

Further, by adjusting the parameters of the initial light field and changing the composite second-order chirped vortex phase on the transmissive spatial light modulator S2, the position, shape and number of the off-axis optical bottle can be continuously regulated and controlled:

vortex factor l_i: adjusting the size of the mouth or bottom of each optical bottle_iThe larger the size, the greater the yieldThe wider the mouth of the raw optical bottle;

chirp displacement factor (x)_i,y_i): adjusting the degree of the off-axis light beam deviating from the optical axis so as to control the position of the off-axis optical bottle in space; if (x)_i,y_i) (0,0), then the optical bottle is generated on the optical axis, being an on-axis optical bottle;

second order chirp factor c_i: adjusting the distance between the bottle mouth and the bottle bottom of the off-axis optical bottle and the initial plane and the length of each off-axis optical bottle;

number of second-order chirped vortex phases N: adjusting the number of off-axis optical bottles, when there are N chirped phase factors, then N-1 optical bottles can be produced.

Further, the spatial filter system includes a lens L1, a diaphragm, and a lens L2; the input light field is subjected to Fourier transform through a lens L1 to obtain a frequency spectrum surface, the diaphragm is used for selecting a positive first-order interference fringe in the frequency spectrum surface, and the output light field, namely a round Pierce Gaussian beam, is obtained through inverse Fourier transform through a lens L2.

In another aspect, the present invention provides a system for producing a highly controllable off-axis optical bottle, comprising:

the computer is used for simulating the interference of the plane wave and the circular Pierce Gaussian beam to obtain a phase hologram, and loading the phase hologram to the reflective spatial light modulator S1; drawing a composite second-order chirped vortex phase according to the optical parameters, and loading the composite second-order chirped vortex phase onto a transmission-type spatial light modulator S2;

a laser for generating a gaussian beam;

a reflective spatial light modulator S1 arranged on the transmission path of the Gaussian beam for loading a phase hologram;

the spatial filtering system is used for receiving the light beam reflected by the reflective spatial light modulator S1, selecting the positive-level stripe of the frequency spectrum surface of the input light field, and obtaining the circular Pierce Gaussian beam at the outlet focal plane of the spatial filtering system;

the transmission type spatial light modulator S2 is arranged at an outlet focal plane of the spatial filtering system and used for loading the composite second-order chirped vortex phase; amplitude and phase modulation can be carried out simultaneously, according to the composite second-order chirped vortex phase and the round Pierce Gaussian beam, the round Pierce Gaussian beam modulated by the composite second-order chirped vortex phase is obtained and is transmitted in vacuum or interference-free air, and multiple times of strong focusing can be formed in the transmission process, so that an off-axis optical bottle is formed;

and the beam quality analyzer is arranged behind the transmission-type spatial light modulator S2 and is used for collecting beam cross section information.

Furthermore, the system for generating the high-controllability off-axis optical bottle further comprises a beam expander, which is arranged at the exit of the laser and used for expanding the Gaussian beam into an approximate plane wave.

Further, the system for generating the high-controllability off-axis optical bottle further comprises a non-polarizing beam splitter, which is arranged between the beam expander and the reflective spatial light modulator S1 and is used for splitting the expanded Gaussian beam; a portion of the light propagates after being transmitted to the reflective spatial light modulator S1.

Further, the spatial filter system includes a lens L1, a diaphragm, and a lens L2; the input light field is subjected to Fourier transform through a lens L1 to obtain a frequency spectrum surface, the diaphragm is used for selecting a positive first-order interference fringe in the frequency spectrum surface, and the output light field, namely a round Pierce Gaussian beam, is obtained through inverse Fourier transform through a lens L2.

Furthermore, the laser is a helium-neon laser, and the wavelength of the generated Gaussian beam is 632.8 nm; the non-polarization beam splitter has a splitting ratio of 1: 1, a non-polarizing beam splitter; the resolution of the beam quality analyzer is 2400 multiplied by 2400, and the beam quality analyzer is used for acquiring the light intensity distribution of the cross section of the light beam; the reflective spatial light modulator S1, the non-polarizing beam splitter, the spatial filtering system and the transmissive spatial light modulator S2 are arranged on the same axis; the laser, the beam expander and the non-polarization beam splitter are arranged on the same axis.

Compared with the prior art, the invention has the beneficial effects that at least:

the invention provides a system for generating a high-controllability off-axis optical bottle, which has a simple structure, the generated optical bottle has higher off-axis degree and strong controllability, and the fast adjustment of the optical bottle can be realized only by changing the loaded composite second-order chirp vortex phase on a transmission-type spatial light modulator S2 without reloading a phase hologram or reselecting a primary stripe in a spatial filter, thereby realizing the continuous regulation and control of the off-axis optical bottle. In summary, the present invention is more efficient in particle capture and manipulation and has a high degree of freedom.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a flow chart of a method of producing a highly controllable off-axis optical bottle according to the present invention;

FIG. 2 is a block diagram of a system for creating a highly controllable off-axis optical bottle according to the present invention;

fig. 3 is a phase hologram loaded on the reflective spatial light modulator S1 in the first and second embodiments;

FIG. 4 is a schematic diagram of amplitude modulation of a circular Pierce Gaussian beam by a composite second-order chirped vortex phase; (a1) is the amplitude distribution of a round pierce gaussian beam; (a2) the amplitude distribution of the composite second-order chirped vortex phase; (a3) the amplitude distribution of the circular Pierce Gaussian beam modulated by the composite second-order chirp vortex phase;

FIG. 5 is a schematic diagram of phase modulation of a circular Pierce Gaussian beam by a composite second-order chirped vortex phase; (a1) is the phase distribution of a round Pierce Gaussian beam; (a2) phase distribution of the composite second-order chirped vortex phase; (a3) the phase distribution of the circular Pierce Gaussian beam modulated by the composite second-order chirp vortex phase is obtained;

FIG. 6 is a schematic view of a first embodiment of the present application; (a) the light field distribution diagram of a certain Z-X plane of the light beam. (b1) - (b4) transverse cross-sectional views of the light beam at the initial plane, at the mouth, at the body and at the bottom, respectively;

FIG. 7 is a schematic view of a second embodiment of the present application; (a) a light field distribution diagram of a certain Z-X plane of the light beam; (b1) - (b4) are transverse cross-sectional views of the light beam in the initial plane and of the mouth, body and bottom of one of the light bottles, respectively;

FIG. 8(a1) is the amplitude distribution of the complex second-order chirped vortex phase loaded on the transmissive spatial light modulator S2 according to the first embodiment; (a2) the phase distribution of the composite second-order chirped vortex phase loaded on the transmissive spatial light modulator S2 in the first embodiment; (b1) the amplitude distribution of the composite second-order chirped vortex phase loaded on the transmissive spatial light modulator S2 in the second embodiment; (b2) the phase distribution of the complex second-order chirped vortex phase loaded on the transmissive spatial light modulator S2 in the second embodiment is shown.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. It should be noted that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.

As shown in FIG. 1, the present invention provides a method for producing a highly controllable off-axis optical bottle, comprising the steps of:

s01, simulating interference of plane waves and circular Pierce Gaussian beams by using a computer to obtain a phase hologram, and loading the phase hologram to the reflective spatial light modulator S1;

s02, drawing a composite second-order chirped vortex phase on a computer according to the optical parameters, and loading the composite second-order chirped vortex phase on the transmission-type spatial light modulator S2;

s03, using Gaussian beam to irradiate the reflective spatial light modulator S1, making the reflected light pass through a spatial filtering system, and selecting a positive-level stripe in the spatial filtering system to obtain a round Pierce Gaussian beam;

s04, enabling the round Pierce Gaussian beam to pass through the transmission type spatial light modulator S2 to obtain the round Pierce Gaussian beam modulated by the composite second-order chirp vortex phase, enabling the round Pierce Gaussian beam to be transmitted in vacuum or interference-free air, and forming multiple times of strong focusing in the transmission process, thereby forming the off-axis optical bottle.

As shown in fig. 2, the present invention provides a system for generating a highly controllable off-axis optical bottle, which includes a computer, a he — ne laser, a beam expander, a non-polarizing beam splitter, a reflective spatial light modulator S1, a spatial filtering system, a transmissive spatial light modulator S2, and a beam quality analyzer;

the computer is used for simulating the interference of plane waves and circular Pierce Gaussian beams to obtain a phase hologram, and loading the phase hologram to the reflective spatial light modulator S1; drawing a composite second-order chirped vortex phase according to the optical parameters, and loading the composite second-order chirped vortex phase onto a transmission-type spatial light modulator S2;

the helium-neon laser is used for generating a Gaussian beam; the wavelength of a Gaussian beam generated by the helium-neon laser is 632.8 nm;

the beam expander is arranged at the exit of the laser and is used for expanding the Gaussian beam into an approximate plane wave;

the non-polarization beam splitter is arranged between the beam expander and the reflective spatial light modulator S1 and is used for splitting the expanded Gaussian beam, and a part of the expanded Gaussian beam is transmitted to the reflective spatial light modulator S1 and then is transmitted continuously; the non-polarization beam splitter has a splitting ratio of 1: 1;

the reflective spatial light modulator S1 is arranged on the transmission path of the Gaussian beam and is used for loading a phase hologram;

the spatial filtering system is used for receiving the light beam reflected by the reflective spatial light modulator S1, selecting the positive-level stripe of the frequency spectrum surface of the input light field, and obtaining the circular Pierce Gaussian beam at the outlet focal plane of the spatial filtering system;

the transmission type spatial light modulator S2 is arranged at an outlet focal plane of the spatial filtering system and used for loading a composite second-order chirped vortex phase; amplitude and phase modulation can be carried out simultaneously, according to the composite second-order chirped vortex phase and the round Pierce Gaussian beam, the round Pierce Gaussian beam modulated by the composite second-order chirped vortex phase is obtained and is transmitted in vacuum or interference-free air, and multiple times of strong focusing can be formed in the transmission process, so that an off-axis optical bottle is formed;

the beam quality analyzer is arranged behind the transmission-type spatial light modulator S2 and is used for collecting beam cross section information; the resolution of the beam quality analyzer is 2400 x 2400, and the light intensity distribution of the beam cross section is obtained.

In particular, the spatial filtering system comprises a lens L1, a diaphragm and a lens L2; the input light field is subjected to Fourier transform through a lens L1 to obtain a frequency spectrum surface, the diaphragm is used for selecting a positive first-order interference fringe in the frequency spectrum surface, and the output light field, namely a round Pierce Gaussian beam, is obtained through inverse Fourier transform through a lens L2.

The reflective spatial light modulator S1, the non-polarizing beam splitter, the spatial filtering system and the transmissive spatial light modulator S2 are arranged on the same axis; the laser, the beam expander and the non-polarization beam splitter are arranged on the same axis.

It should be noted that the specific modulation of the circular pierce gaussian beam modulated by the composite second-order chirped vortex phase is as follows:

the analytic formula of the circular Pierce Gaussian beam in the initial plane is as follows:

wherein the content of the first and second substances,

defined as the Pears integral, x₀As a scaling factor of the content dimension, w₀Is gaussian beam width. Simulation of circular Pearss Gaussian beam and plane wave interference by computerAnd obtaining a phase hologram, loading the phase hologram on a reflective spatial light modulator S1, irradiating by using the Gaussian beam, and obtaining emergent light filtered by a spatial filtering system, namely the round Pierce Gaussian beam.

The phase hologram loaded onto the reflective spatial light modulator S1 is shown in fig. 3.

It should be noted that the specific processes of the circular pierce gaussian beam modulated by the composite second-order chirped vortex phase are as follows:

the analytical expression of the composite second-order chirped vortex phase is as follows:

wherein, c_iIs a second order chirp factor,/_iIs the vortex order, (x)_i,y_i) For the displacement factor, N is the number of second order chirped vortex phases, and (x)_i,y_i) The conditions are satisfied: x is the number of_i＝c₁x₁/c_i,y_i＝c₁y₁/c_i(ii) a The analytic expression of the round pierce gaussian beam after passing through the transmissive spatial light modulator S2 is:in mathematics, the propagation characteristics of a composite second-order chirped vortex phase modulated circular pierce gaussian beam in free space can be expressed by paraxial wave equations expressed in cylindrical coordinates:

is the wavenumber, and λ is the wavelength. And drawing a composite second-order chirped vortex phase on a computer, loading the composite second-order chirped vortex phase on the transmission-type spatial light modulator S2, and enabling a round Pierce Gaussian beam to be incident, wherein emergent light is the round Pierce Gaussian beam modulated by the composite second-order chirped vortex phase.

The modulation of the circular pierce gaussian beam by the composite second-order chirped vortex phase loaded on the transmissive spatial light modulator S2 is shown in fig. 4 and 5.

The invention can realize the continuous regulation and control of the position, the shape and the number of the off-axis optical bottles by adjusting the parameters of the initial light field and changing the composite second-order chirp vortex phase on the transmission-type spatial light modulator S2:

vortex factor l_i: adjusting the size of the mouth or bottom of each optical bottle_iThe larger the bottle mouth, the wider the resulting optical bottle;

chirp displacement factor (x)_i,y_i): adjusting the degree of the off-axis light beam deviating from the optical axis so as to control the position of the off-axis optical bottle in space; if (x)_i,y_i) (0,0), then the optical bottle is generated on the optical axis, being an on-axis optical bottle;

second order chirp factor c_i: and adjusting the distance between the bottle mouth and the bottle bottom of the off-axis optical bottle and the initial plane, and the length of each off-axis optical bottle.

Number of second-order chirped vortex phases N: adjusting the number of off-axis optical bottles, when there are N chirped phase factors, then N-1 optical bottles can be produced.

Example one

In the first embodiment, which is consistent with fig. 6, the composite second-order chirped vortex phase modulated round pierce gaussian beam under this condition can stably generate an off-axis optical bottle in free space, which is farther from the initial plane, closer to the optical axis, wider at the bottom, narrower at the mouth, and longer at the body.

S01, simulating the interference of plane waves and circular Pierce Gaussian beams by using a computer to obtain a phase hologram, and loading the phase hologram on the reflective spatial light modulator S1.

S02, drawing the composite second-order chirped vortex phase (N is 2, l) on the computer according to the optical parameters₁＝3，l₂＝3，c₁＝0.35，c₂＝0.25，(x₁,y₁) 0.0011, 0)) and loaded onto a transmissive spatial light modulator S2, a complex second order chirpThe phases of the chirped vortices are shown in FIG. 8 (a).

S03, irradiating the reflective spatial light modulator with a light beam S1 to enable the reflected light to pass through a spatial filtering system, and selecting a positive-level stripe in the spatial filtering system to obtain a circular Pierce Gaussian light beam;

s04, enabling the round Pierce Gaussian beam to pass through the transmission type spatial light modulator S2 to obtain the round Pierce Gaussian beam modulated by the composite second-order chirp vortex phase, enabling the round Pierce Gaussian beam to be transmitted in vacuum or interference-free air, and forming multiple times of strong focusing in the transmission process, thereby forming the off-axis optical bottle.

All corresponding parameters of this first embodiment are identical to those of fig. 6.

Setting other parameters: x is the number of₀＝0.15mm，w₀＝4mm。

Example two

The second embodiment is identical to fig. 7, under the condition, the circular pierce gaussian beam modulated by the composite second-order chirped vortex phase can stably generate an off-axis optical bottle which is close to the initial plane, far from the optical axis, narrow at the bottom, wide at the mouth and long in the body in the free space.

S01, simulating the interference of plane waves and circular Pierce Gaussian beams by using a computer to obtain a phase hologram, and loading the phase hologram on the reflective spatial light modulator S1.

S02, drawing the composite second-order chirped vortex phase (N is 3, l) on the computer according to the optical parameters₁＝2，l₂＝2，l₃＝2，c₁＝0.35，c₂＝0.25，c₃＝0.18，(x₁,y₁) (0.0005, 0)), and loaded onto transmissive spatial light modulator S2, the composite second order chirped vortex phase is shown in fig. 8 (b).

S03, irradiating the reflective spatial light modulator with a light beam S1 to enable the reflected light to pass through a spatial filtering system, and selecting a positive-level stripe in the spatial filtering system to obtain a circular Pierce Gaussian light beam;

s04, enabling the round Pierce Gaussian beam to pass through the transmission type spatial light modulator S2 to obtain the round Pierce Gaussian beam modulated by the composite second-order chirp vortex phase, enabling the round Pierce Gaussian beam to be transmitted in vacuum or interference-free air, and forming multiple times of strong focusing in the transmission process, thereby forming the off-axis optical bottle.

All corresponding parameters of this second embodiment are identical to those of fig. 7.

Setting other parameters: x is the number of₀＝0.15mm，w₀＝4mm。

The invention combines the circular Pierce light beam, the second-order chirp and the vortex, so that the light beam can spontaneously generate an off-axis optical bottle in the transmission process.

The invention adopts a reflection type spatial light modulator and a transmission type spatial light modulator to generate the off-axis optical bottle, and adopts the transmission type spatial light modulator to change the parameters of the off-axis optical bottle without changing the phase hologram on the reflection type spatial light modulator and reselecting the stripe in the spatial filter, thereby improving the efficiency, well controlling the generation of the light beam and the generation of the shape of the off-axis optical bottle and enabling the continuous regulation and control of the off-axis optical bottle to be possible.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.