A method and device for detecting topological charge of vortex light based on self-rotating light beam phase

Abstract

The present invention discloses a method and device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam, the method comprising: loading a vortex phase hologram carrying the phase of a self-rotating light beam into a spatial light modulator; using a linearly polarized Gaussian light beam to be incident on the spatial light modulator to generate a vortex light beam carrying the phase of the self-rotating light beam and an arbitrary topological charge; wherein the linearly polarized Gaussian light beam is coaxial with the vortex phase center loaded by the spatial light modulator; obtaining a far-field diffraction intensity distribution diagram of the vortex light beam after passing through an imaging lens; determining the positive and negative and size of the topological charge of the vortex light beam according to the far-field diffraction intensity distribution diagram. The optical path of the present invention is simple, and the preparation and detection of vortex light can be realized by using the same optical path, with low cost; the positive and negative topological charge of the vortex light is clearly distinguished, and the detection accuracy is high, and it has great application potential in the fields of optical micro-manipulation, optical communication, optical information storage encryption, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of vortex light topological charge detection, and in particular to a method and device for detecting vortex light topological charge based on a self-rotating light beam phase. Background Art

[0002] Vortex light is a special light beam with a spiral phase wavefront and a certain orbital angular momentum. It can be generated by computer holography, mode transfer and spiral phase plate. In recent years, vortex beams have been widely used in optical trapping, optical tweezers, image processing, optical communication and quantum information technology. Most of these applications are based on the orbital angular momentum carried by vortex light. The existence of orbital angular momentum is related to the phase function ψ of vortex light. vortex = lθ (θ is the angle in polar coordinates, l is the topological charge), each photon in the vortex light carries The orbital angular momentum ( is the reduced Planck constant). It can be seen that determining the orbital angular momentum of the photon requires determining the topological charge of the vortex light. The phase singularity at the center of the vortex light wavefront creates a dark spot in the transverse intensity distribution of the vortex light, which is similar to a hollow "donut". The diameter of the "donut" increases with the increase of the topological charge. However, the topological charge of the vortex light cannot be directly observed from the intensity distribution.

[0003] At present, there are three main methods for measuring the topological charge of vortex light: interferometry, diffraction measurement, and vortex light intensity analysis. The first method involves bulky interferometry equipment, finely arranged optical elements, and complex interference patterns; the second method usually converts the vortex beam into a recognizable pattern through special elements such as astigmatism elements, diffraction apertures, or gratings; the third method requires the use of complex algorithms to perform intensity analysis on the vortex beam in order to determine the topological charge. In a laboratory environment, the spatial light modulator method can make up for the above shortcomings. The spatial light modulator is small in size and easy to use. By controlling the loaded holographic image to separate the diffraction orders, the beam quality can be improved. The phase of the self-rotating beam is loaded into the spatial light modulator, and the detection of the topological charge of the vortex light can be achieved by capturing the focal plane intensity distribution and analyzing it.

[0004] Therefore, it is necessary to provide a method and device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam, which can easily study and measure the topological charge of vortex light under laboratory conditions, reduce the detection cost of the topological charge of vortex light and improve the detection accuracy. Summary of the invention

[0005] In view of this, the present invention provides a method and device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam, so as to solve the technical problems of complex detection process and high cost of detection equipment in the existing vortex light topological charge detection.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for detecting the topological charge of a vortex light based on the phase of a self-rotating light beam, comprising:

[0008] A vortex phase hologram carrying the phase of a self-rotating light beam is loaded into a spatial light modulator;

[0009] A linearly polarized Gaussian beam is incident on the spatial light modulator to generate a vortex beam carrying a self-rotating beam phase and an arbitrary topological charge number; wherein the linearly polarized Gaussian beam is coaxial with the vortex phase center loaded by the spatial light modulator;

[0010] Obtaining a far-field diffraction intensity distribution diagram of the vortex light beam after passing through an imaging lens;

[0011] The positive and negative sign and size of the topological charge of the vortex beam are determined according to the far-field diffraction intensity distribution diagram.

[0012] Furthermore, the functional expression of the self-rotating beam phase in the polar coordinate system is:

[0013]

[0014] Wherein, (r, θ) represents a polar coordinate system, r0 is a normalization factor of r, a is an arbitrary constant, θ0 is the rotation angle of the self-rotating light beam, and n is a non-zero integer representing the number of self-rotating light beams.

[0015] Furthermore, the linearly polarized Gaussian beam before incident is expressed in the polar coordinate system as follows:

[0016] E=A0exp(-r 2 / w 2 )

[0017] Where (r, θ) represents the polar coordinate system, A0 is the amplitude, and w is the waist radius of the Gaussian beam.

[0018] Further, determining the sign and magnitude of the topological charge of the vortex beam according to the far-field diffraction intensity distribution diagram includes:

[0019] When light and dark fringes appear in the middle of the intensity distribution diagram, it is determined that the topological charge of the vortex is negative, and the number of dark fringes is equal to the topological charge of the vortex light;

[0020] When no light or dark stripes appear in the intensity distribution diagram, the topological charge of the vortex is determined to be positive, the self-rotating light beam in the intensity distribution moves away from the center of the light field, and its scale is compressed, and the scale ratio change corresponds one-to-one to the topological charge of the vortex light.

[0021] Furthermore, the obtaining of the far-field diffraction intensity distribution diagram of the vortex light beam after passing through the imaging lens includes:

[0022] The field in the Fraunhofer diffraction zone is calculated by the two-dimensional fast Fourier transform of the initial field, which is expressed as:

[0023]

[0024] in, represents Fourier transform, and E0 represents the initial field.

[0025] Furthermore, the step of obtaining the far-field diffraction intensity distribution diagram of the vortex light beam after passing through the imaging lens further includes:

[0026] The intensity distribution pattern is determined using a matrix triple product operation, which is expressed as:

[0027] E=Ω y E0Ω x

[0028] Among them, Ω y =exp(-i2πY T K y ),Ω x =exp(-i2πK x T X); K x , K y , X, Y are the coordinates of the spatial frequency domain and the spatial domain represented by row vectors respectively, and the symbol T represents the transpose operation.

[0029] Furthermore, the linearly polarized Gaussian beam is a fundamental mode Gaussian beam or a near-Gaussian beam.

[0030] The present invention also provides a device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam, comprising a laser, a linear polarizer, a first lens, a second lens, an aperture stop, a spatial light modulator, an imaging lens and a light beam detector connected in sequence;

[0031] The Gaussian beam emitted by the laser is incident on the spatial light modulator through a linear polarizer, a first lens, a second lens and an aperture stop in sequence, and a phase hologram is loaded on the spatial light modulator to form a vortex beam with an arbitrary topological charge number carrying the phase of the self-rotating beam;

[0032] The generated vortex beam passes through the imaging lens and is captured and recorded by the beam detector to obtain the generated far-field diffraction intensity pattern.

[0033] Furthermore, the first lens and the second lens are both weak focusing positive lenses.

[0034] Furthermore, the light beam detector is a CCD camera.

[0035] The method for detecting the topological charge of vortex light based on the phase of a self-rotating light beam provided by the present invention comprises the following steps: producing a vortex phase hologram carrying the phase of a self-rotating light beam and loading it into a spatial light modulator, irradiating the spatial light modulator with linearly polarized Gaussian light, and generating an intensity distribution related to the topological charge of the vortex light beam at the focal plane after the emergent light passes through an imaging lens. The positive and negative sign and size of the topological charge of the vortex light can be observed based on the intensity distribution diagram.

[0036] Compared with the existing technology, the main advantages of this method are: (1) the optical path is simple, and the conventional optical path of the optical laboratory can be used to detect the optical path, and there are no other requirements for the construction of the optical path; (2) low cost, this method only needs to use the same optical path to achieve the preparation and detection of vortex light; (3) high accuracy, the positive and negative topological charges of the vortex light are clearly distinguished, and the accuracy of detecting the topological charge of the vortex light is high; (4) strong practicality, the vortex light beam carrying the self-rotating light beam phase generated by this method has great application potential in the fields of optical micromanipulation, optical communication, optical information storage and encryption, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic flow chart of an embodiment of a method for detecting the topological charge of vortex light based on the phase of a self-rotating light beam provided by the present invention;

[0038] Figure 2 A schematic diagram of drawing a vortex light hologram when the topological charge number provided by the present invention is 5;

[0039] Figure 3 A schematic diagram of a vortex beam carrying a self-rotating beam phase with a topological charge number of -1 to -10 provided by the present invention;

[0040] Figure 4 A schematic diagram of a vortex beam carrying a self-rotating beam phase with a topological charge number of 1 to 10 provided by the present invention;

[0041] Figure 5 A schematic diagram of the structure of a device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam provided by the present invention. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0043] The present invention provides a method and device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam, which are respectively described below.

[0044] A specific embodiment of the present invention discloses a method for detecting the topological charge of a vortex light based on the phase of a self-rotating light beam. Figure 1 is a flow chart of the method for detecting the topological charge of vortex light based on the phase of a self-rotating light beam, such as Figure 1 As shown, the method includes:

[0045] Step S101: loading a vortex phase hologram carrying a self-rotating light beam phase into a spatial light modulator;

[0046] Step S102: using a linearly polarized Gaussian beam to be incident on the spatial light modulator to generate a vortex beam carrying a self-rotating beam phase and an arbitrary topological charge; wherein the linearly polarized Gaussian beam is coaxial with the vortex phase center loaded by the spatial light modulator;

[0047] Step S103: obtaining a far-field diffraction intensity distribution diagram of the vortex light beam after passing through an imaging lens;

[0048] Step S104: determining the sign and magnitude of the topological charge of the vortex beam according to the far-field diffraction intensity distribution diagram.

[0049] The principle of the method in this embodiment is: after the vortex light carries the phase of the self-rotating light beam, the intensity distribution at the focal plane of the imaging lens is still the self-rotating light beam intensity distribution mode as a whole, but the positive and negative and size of the vortex light topological charge will affect the intensity distribution mode, specifically: when the topological charge of the vortex is positive, the self-rotating light beam in the intensity distribution is away from the center of the light field, and its scale is compressed, and the scale ratio change corresponds one-to-one to the topological charge of the vortex light; when the topological charge of the vortex is negative, light and dark stripes will appear in the middle of the intensity distribution, and the number of dark stripes is equal to the topological charge of the vortex light.

[0050] Therefore, this method makes a vortex phase hologram carrying the phase of a rotating light beam and loads it into a spatial light modulator. A beam of linearly polarized Gaussian light is irradiated onto the spatial light modulator. After the outgoing light passes through an imaging lens, an intensity distribution related to the topological charge of the vortex light beam is generated at the focal plane. The positive and negative and size of the topological charge of the vortex light can be observed based on the intensity distribution diagram.

[0051] Compared with the existing technology, the main advantages of this method are: (1) the optical path is simple, and the conventional optical path of the optical laboratory can be used to detect the optical path, and there are no other requirements for the construction of the optical path; (2) low cost, this method only needs to use the same optical path to achieve the preparation and detection of vortex light; (3) high accuracy, the positive and negative topological charges of the vortex light are clearly distinguished, and the accuracy of detecting the topological charge of the vortex light is high; (4) strong practicality, the vortex light beam carrying the self-rotating light beam phase generated by this method has potential applications in optical micromanipulation, optical communication, optical information storage and encryption and other fields.

[0052] As a preferred embodiment, the functional expression of the self-rotating light beam phase in the polar coordinate system is:

[0053]

[0054] Wherein, (r, θ) represents a polar coordinate system, r0 is a normalization factor of r, a is an arbitrary constant, θ0 is the rotation angle of the self-rotating light beam, and n is a non-zero integer representing the number of self-rotating light beams.

[0055] As a specific embodiment, assuming a=200, θ0=0, taking the vortex light with topological charge number l=5 as an example, after superimposing the vortex hologram with l=5 and the self-rotation phase with n=2, a holographic pattern that can be precisely controlled is obtained, such as Figure 2 shown.

[0056] A beam of linearly polarized Gaussian light is incident on the spatial light modulator. The expression of the linearly polarized Gaussian light before the incident is: E = A0exp(-r 2 / w 2 ), where (r, θ) represents the polar coordinate system, A0 is the amplitude, and w is the waist radius of the Gaussian beam.

[0057] In some embodiments, the spatial line shape of the linearly polarized Gaussian light laser beam is a fundamental mode Gaussian beam or a near-Gaussian beam. The cross section of the fundamental mode Gaussian light is a Gaussian distribution, and the light intensity is Gaussian with the increase of radial distance, that is, the transverse mode is a Gaussian mode. A near-Gaussian beam refers to a beam that is close to a Gaussian beam in practical applications but does not completely conform to the characteristics of an ideal Gaussian beam. Its Gaussian characteristics can still guarantee good optical imaging and transmission quality, so it is still widely used in practice.

[0058] Furthermore, at the initial plane (propagation distance z = 0), the expression of the vortex beam carrying the self-rotating beam phase is:

[0059]

[0060] Where (r, θ) represents the polar coordinate system, l is the topological charge, w is the initial radius of the Gaussian beam, and ψ is the phase of the self-rotating beam.

[0061] Using the paraxial approximation, the field in the Fraunhofer diffraction region can be calculated by the 2D fast Fourier transform of the initial field: in, is the Fourier transform.

[0062] In some embodiments, in order to eliminate the fixed sampling relationship between the initial plane and the far-field plane, thereby obtaining a more accurate intensity distribution pattern, a matrix triple product operation may be used to replace the traditional Fourier transform operation, which is expressed as follows:

[0063] E=Ω y E0Ω x

[0064] Among them, Ω x =exp(-i2πK x T X),Ω y =exp(-i2πY T K y );K x , K y , X, Y are the coordinates of the spatial frequency domain and spatial domain represented by row vectors respectively, and the symbol "T" represents the transpose operation.

[0065] The intensity of the beam is expressed as I = E * E.

[0066] The far-field diffraction intensity patterns of vortex beams with different topological charges after the self-rotating beam phase are recorded respectively, and the relationship between the diffraction pattern and the topological charge of the vortex beam is analyzed through the diffraction intensity pattern.

[0067] As a preferred embodiment, determining the sign and magnitude of the topological charge of the vortex beam according to the far-field diffraction intensity distribution diagram specifically includes:

[0068] When light and dark fringes appear in the middle of the intensity distribution diagram, the topological charge of the vortex is negative, and the number of dark fringes is equal to the topological charge of the vortex light;

[0069] When no light or dark stripes appear in the intensity distribution diagram, the topological charge of the vortex is positive, the self-rotating light beam in the intensity distribution moves away from the center of the light field, and its scale is compressed, and the scale ratio change corresponds one-to-one to the topological charge of the vortex light.

[0070] The sign of the topological charge of a vortex beam depends on the direction of rotation. A positive topological charge indicates clockwise rotation, and a negative topological charge indicates counterclockwise rotation. The magnitude of the topological charge of a vortex beam is usually expressed as an integer, representing the unit rotation carried by each photon in the vortex structure. For example, a topological charge of ±1 means that each photon carries one quantum rotation.

[0071] Combine the following Figure 3 and Figure 4 The pattern results of the vortex beam carrying the self-rotating beam phase in the far field are given as examples with topological charges ranging from -1 to -10 and from 1 to 10, and the topological charge analysis is performed.

[0072] Figure 3 From left to right in the figure are vortex beams carrying self-rotating beam phases with topological charges ranging from -1 to -10, and from top to bottom are the far-field simulated intensity distribution, the far-field experimental intensity distribution, and the normalized intensity change curve on the horizontal line in the middle of the intensity distribution, where the red curve corresponds to the simulated intensity and the green curve corresponds to the experimental intensity. It can be seen that the number of dark stripes in the far-field intensity distribution is the topological charge of the vortex light, but in reality, since the intensity of the outermost bright stripes is very weak, the topological charge of the vortex beam is one more than the number of bright stripes, which is also the basis for us to judge the topological charge less than zero.

[0073] Figure 4 From top to bottom, the vortex beams carrying the self-rotating beam phase with topological charges of 1 to 10 are shown, and from left to right, they are the far-field simulated intensity distribution diagram, the far-field experimental intensity distribution diagram, and the normalized intensity change curve on the horizontal line in the middle of the intensity distribution diagram, where the red curve corresponds to the simulated intensity and the green curve corresponds to the experimental intensity. When the topological charge is positive, the value of ξ corresponds to the value of the topological charge. For example, when the topological charge is 5, the value of ξ should be around 4.26. However, the value of ξ will change due to changes in parameters such as the focal length of the lens and the self-rotating beam parameter a, but the value of ξ will only fluctuate very slightly (no more than 0.1). The proportional relationship between D and d1 and d2 in the simulated intensity distribution diagram with a topological charge of 1 is: ξ=D / [(d1+d2) / 2] (the value of ξ is the aforementioned scale ratio). It can be seen that the value of ξ increases with the increase of the topological charge value of the vortex beam, and the experiment is in good agreement with the theory, which is also the basis for us to judge the topological charge greater than zero.

[0074] The embodiment of the present invention also provides a device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam, such as Figure 5 As shown, the device includes a laser 1, a linear polarizer 2, a first lens 3, a second lens 4, an aperture stop 5, a spatial light modulator 6, an imaging lens 7 and a CCD camera 8 connected in sequence;

[0075] The Gaussian light beam emitted by the laser 1 passes through a linear polarizer 2, a first lens 3, a second lens 4 and an aperture stop 5 and is incident on a spatial light modulator 6. A phase hologram is loaded on the spatial light modulator 6 to form a vortex light beam with an arbitrary topological charge number carrying the phase of the self-rotating light beam. After the generated vortex light beam passes through an imaging lens 7, it is captured by a CCD camera 8 to record the generated far-field diffraction intensity pattern.

[0076] In some embodiments, the spatial line shape of the laser beam emitted by the laser 1 is a fundamental mode Gaussian beam or a near-Gaussian beam, and the wavelength of the selected laser beam is 532nm. The Gaussian beam emitted by the laser 1 is incident on the spatial light modulator, and the output power is 1mW. By loading a phase hologram on the spatial light modulator, a vortex beam with any topological charge number carrying the phase of the self-rotating beam can be generated. After the generated vortex beam passes through the imaging lens, it is captured and recorded by the CCD camera to produce a far-field diffraction intensity pattern.

[0077] The steps for detecting the topological charge of a vortex beam using the above device are as follows:

[0078] The first step is to build the optical path and adjust the position of the spatial light modulator to ensure that the spiral phase center loaded by the spatial light modulator is coaxial with the light beam;

[0079] The second step is to make a vortex phase hologram carrying the phase of the self-rotating beam and load it into a spatial light modulator. After the fundamental mode Gaussian light is irradiated on the spatial light modulator, a vortex beam carrying the phase of the self-rotating beam is generated.

[0080] In the third step, when it is transmitted to the far field, it is captured by a CCD camera, and the positive and negative topological charge of the vortex light and the specific value of the topological charge are analyzed and recorded respectively, thus completing the detection of the topological charge of the vortex light.

[0081] As a preferred embodiment, the first lens 3 and the second lens 4 are both weak focusing positive lenses. Under weak focusing conditions (or paraxial approximation), the propagation of light in the optical system can be described by approximate linear optical theory, which greatly simplifies the analysis of the optical system. For example, the Fourier optical method or transfer function analysis can be used to quickly derive the transmission characteristics of the system without considering complex nonlinear optical effects.

[0082] The method and device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam provided by the present invention can detect the topological charge of vortex light based on the phase of a self-rotating light beam. Specifically, the far-field diffraction intensity pattern can be changed by allowing the vortex light to carry the phase of the self-rotating light beam. For vortex light with a topological charge greater than zero, the topological charge of the vortex light beam can be determined by analyzing the value of ξ. For vortex light with a topological charge less than zero, the topological charge of the vortex light beam can be determined by analyzing the number of bright stripes in the far-field diffraction pattern. In short, the topological charge of the vortex light beam can be accurately determined by analyzing the far-field diffraction intensity pattern. Not only is the method novel and the experiment simple, but the results are also intuitive and accurate.

[0083] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for detecting the topological charge of vortex light based on the phase of a self-rotating light beam, characterized in that: include: The vortex phase hologram carrying the self-rotating beam phase is loaded into the spatial light modulator; the function expression of the self-rotating beam phase in the polar coordinate system is: Wherein, (r, θ) represents the polar coordinate system, r0 is the normalization factor of r, a is an arbitrary constant, θ0 is the rotation angle of the self-rotating beam, and n is a non-zero integer representing the number of self-rotating beams; A linearly polarized Gaussian beam is incident on the spatial light modulator to generate a vortex beam carrying a self-rotating beam phase and an arbitrary topological charge number; wherein the linearly polarized Gaussian beam is coaxial with the vortex phase center loaded by the spatial light modulator; Obtaining a far-field diffraction intensity distribution diagram of the vortex light beam after passing through an imaging lens; Determining the sign and magnitude of the topological charge of the vortex beam according to the far-field diffraction intensity distribution diagram includes: When light and dark fringes appear in the middle of the intensity distribution diagram, it is determined that the topological charge of the vortex is negative, and the number of dark fringes is equal to the topological charge of the vortex light; When no light or dark stripes appear in the intensity distribution diagram, the topological charge of the vortex is determined to be positive, the self-rotating light beam in the intensity distribution moves away from the center of the light field, and its scale is compressed, and the scale ratio change corresponds one-to-one to the topological charge of the vortex light.

2. The method for detecting the topological charge of vortex light based on the phase of a self-rotating light beam according to claim 1, characterized in that: The expression of the linearly polarized Gaussian beam before incident in the polar coordinate system is: E=A0exp(-r 2 / w 2 ) Where (r, θ) represents the polar coordinate system, A0 is the amplitude, and w is the waist radius of the Gaussian beam.

3. The method for detecting the topological charge of vortex light based on the phase of a self-rotating light beam according to claim 1, characterized in that: The step of obtaining a far-field diffraction intensity distribution diagram of the vortex light beam after passing through an imaging lens comprises: The field in the Fraunhofer diffraction zone is calculated by the two-dimensional fast Fourier transform of the initial field, which is expressed as: in, represents Fourier transform, and E0 represents the initial field.

4. The method for detecting the topological charge of vortex light based on the phase of a self-rotating light beam according to claim 1, characterized in that: The step of obtaining a far-field diffraction intensity distribution diagram of the vortex light beam after passing through an imaging lens further includes: The intensity distribution pattern is determined using a matrix triple product operation, which is expressed as: E=Ω y E0Ω x Among them, Ω y =exp(-i2πY T K y ), Kx, Ky, X, and Y are the coordinates of the spatial frequency domain and the spatial domain represented by row vectors respectively, and the symbol T represents the transposition operation.

5. The method for detecting the topological charge of vortex light based on the phase of a self-rotating light beam according to claim 1, characterized in that: The linearly polarized Gaussian beam is a fundamental mode Gaussian beam or a near-Gaussian beam.

6. A device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam according to claim 1, characterized in that: It comprises a laser (1), a linear polarizer (2), a first lens (3), a second lens (4), an aperture stop (5), a spatial light modulator (6), an imaging lens (7) and a beam detector (8) which are connected in sequence; The Gaussian light beam emitted by the laser (1) passes through a linear polarizer (2), a first lens (3), a second lens (4) and an aperture stop (5) in sequence and is incident on a spatial light modulator (6), and a phase hologram is loaded on the spatial light modulator (6) to form a vortex light beam with an arbitrary topological charge number carrying the phase of the self-rotating light beam; The generated vortex light beam passes through the imaging lens (7) and is captured and recorded by the light beam detector (8), thereby obtaining the generated far-field diffraction intensity pattern.

7. The device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam according to claim 6 is characterized in that: The first lens (3) and the second lens (4) are both weak focusing positive lenses.

8. The device for detecting the topological charge of vortex light based on the phase of a self-rotating light beam according to claim 7 is characterized in that: The light beam detector is a CCD camera.

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