Method for regulating and controlling arbitrarily arranged array light beams based on optical convolution effect

Abstract

The invention relates to a method for regulating and controlling arbitrarily arranged array light beams based on an optical convolution effect, and belongs to the field of light field regulation and control. According to the method, the optical convolution effect is utilized, the holographic phase diagram array arranged in an array mode is used, and array light beams distributed in any light field can be obtained in the far field through Fourier transform. In addition, due to the convolution effect, each sub-light beam in the array light beam obtained through regulation and control is consistent with the incident light beam. Therefore, by changing different incident light beams, an array with randomly arranged corresponding light beams can be obtained. The method does not need a complex phase structure, is flexible to operate, is simple and efficient, and has obvious advantages.

Description

Technical Field

[0001] The present invention belongs to the field of light field control, and in particular relates to a method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect. Background Art

[0002] Compared with a single beam, array beams have more attractive properties. They can work in multiple channels and simultaneously, greatly improving work efficiency. In addition to Gaussian beam arrays, special beam arrays are also gradually showing their advantages. For example, vortex beam arrays can carry orbital angular momentum (OAM), and each photon in the beam will have OAM of size, where It is called the topological charge or mode number. is the reduced Planck constant. The modes of vortex beams are mutually orthogonal and can form a complete orthogonal basis. Therefore, OAM becomes another basic dimension of light and is applied in various fields. Vortex arrays are expected to have better applications in these fields. For example, in the field of optical communications, vortex arrays can perform multi-channel coded communications, greatly improving the communication rate; vortex arrays can capture multiple particles at one time in optical tweezers, and can process multiple units simultaneously in optical processing, greatly improving work efficiency.

[0003] At present, common array control methods mainly include orthogonal gratings, metasurfaces, array spiral phase plates, and Talbot effect. However, these methods have low diffraction efficiency and high-density array beams, requiring high-resolution devices. In addition, these methods can only control two-dimensional arrays in square areas. If you want to achieve an arbitrary arrangement of two-dimensional arrays, you need to customize complex holograms. Moreover, the method of customizing holograms can only generate arrays of corresponding light beams. If you want to generate arrays of other special light beams, you need to customize the holograms again. Therefore, there is an urgent need for a method to flexibly control arbitrarily arranged array beams. Summary of the invention

[0004] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect, comprising the following steps:

[0005] Step 1: According to the Fourier transform principle, the period of the holographic phase pattern array is calculated according to the period of the required array beam;

[0006] Step 2: Calculate the phase structure of each unit in the holographic phase pattern array according to the required intensity distribution of the array beam through the phase inversion algorithm;

[0007] Step 3: combining the period of the holographic phase image array obtained in step 1 and the phase structure of each unit in the holographic phase image array obtained in step 2, and then performing array splicing on the phase structure of each unit to obtain a holographic phase image array;

[0008] Step 4: According to the mode of each sub-beam in the required array beam, the phase structure of the phase hologram plate corresponding to the mode is set to modulate the mode of the incident beam;

[0009] Step 5: The Gaussian beam emitted by the laser passes through the phase holographic plate holographic phase pattern array and the Fourier transform lens in sequence, and an array beam of any arrangement can be obtained in the far field.

[0010] The present invention has the following beneficial effects:

[0011] (1) The present invention provides a method for controlling an arbitrarily arranged array beam based on the optical convolution effect, which can control the array beam without the need for a complex phase structure.

[0012] (2) The present invention provides a method for controlling an arbitrarily arranged array light beam based on the optical convolution effect. By changing the phase structure of each unit in the holographic phase pattern array, an arbitrarily arranged array light beam can be controlled.

[0013] (3) The present invention provides a method for controlling an arbitrarily arranged array of light beams based on the optical convolution effect. The phase hologram and the holographic phase pattern array are independent of each other. By changing different phase holograms, the array control of any light beam can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the optical path for generating a vortex beam array with a specific arrangement, wherein: 1-phase holographic plate, 2-holographic phase pattern array, 3-Fourier transform lens;

[0015] Figure 2 is the target array intensity distribution diagram and its corresponding phase distribution diagram; where, Figure 2 (a) is the target array intensity distribution diagram, Figure 2 (b) is the phase distribution diagram corresponding to the intensity distribution diagram of the target array;

[0016] Figure 3 is a holographic phase pattern array;

[0017] Figure 4 Schematic diagram of phase distribution of a phase hologram plate that modulates the incident light mode;

[0018] Figure 5 It is the vortex beam array after amplitude modulation. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] The present invention proposes a method for controlling an arbitrarily arranged array light beam based on the optical convolution effect. According to the Fourier transform principle, a comb function is also a comb function after Fourier transform. Moreover, the product of two functions is converted into the convolution of the Fourier transforms of the two functions after Fourier transform. Based on these two theorems, the present invention designs a holographic phase pattern array, which can obtain a two-dimensional array of the incident light beam in the far field. At the same time, changing the phase structure of each unit in the holographic phase pattern array can control the amplitude distribution of the far field. In this way, an arbitrarily arranged array light beam can be controlled according to needs.

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] The following is a brief introduction of a method of controlling an arbitrarily arranged array of light beams based on the optical convolution effect of the present invention in conjunction with the accompanying drawings. According to the Fourier transform principle, a two-dimensional array can be written in the form of a comb function, and its Fourier transform is also a comb function, as shown in the following formula:

[0023] (1)

[0024] In the above formula, represents the Fourier transform, are the rectangular coordinates of the input surface, are the rectangular coordinates of the output surface, is a two-dimensional comb function, is the period of the comb function.

[0025] When an incident light beam illuminates a holographic phase pattern array, it can be regarded as the product of the incident light beam and the holographic phase pattern array, as shown in the following formula:

[0026] (2)

[0027] in, represents the incident light field, represents the transmittance function of the holographic phase pattern array, is the period of the holographic phase pattern array, " represents convolution, represents a two-dimensional rectangular function, is a two-dimensional comb function, is the phase structure function of each unit in the holographic phase pattern array, i is an imaginary number, is an exponential function.

[0028] According to the principle of optical convolution, after Fourier transform, formula (2) can be regarded as the convolution of the Fourier transform of the incident light beam and the Fourier transform of the array optical element, as shown in the following formula:

[0029] (3)

[0030] It can be seen from formula (3) that when the incident light beam passes through a holographic phase pattern array, its far field, that is, the light field distribution on the Fourier plane is also a two-dimensional array, and its light field intensity distribution is modulated by the Fourier transform of the phase of each unit in the holographic phase pattern array. Therefore, by modulating the phase structure of each unit in the holographic phase pattern array, arbitrary arrangement of array beam control can be achieved. Moreover, according to formula (3), the output two-dimensional array is the convolution of the Fourier transform of the incident light beam and the comb function. Therefore, by changing the incident light beam, the array arrangement of the corresponding light beam can be obtained. In addition, according to formula (1), the period of the output array beam is The period of the holographic phase pattern array The relationship can be expressed by the following formula:

[0031] (4)

[0032] In the above formula, is the period of the array beam, is the period of the holographic phase pattern array, is the laser wavelength, is the focal length of the Fourier transform lens.

[0033] The method of controlling an arbitrarily arranged array of light beams based on the optical convolution effect of the present invention comprises the following steps:

[0034] Step 1: According to the Fourier transform principle, the period of the holographic phase pattern array is calculated according to the period of the required array beam.

[0035] Step 2: Calculate the phase structure of each unit in the holographic phase pattern array according to the required intensity distribution of the array beam through the phase inversion algorithm; the Fourier transform of the phase structure of each unit in the holographic phase pattern array determines the light field distribution of the array beam, and the control of the array beam with any arrangement can be achieved by modulating the phase structure of each unit in the holographic phase pattern array.

[0036] Step 3: Combine the period of the holographic phase pattern array obtained in step 1 and the phase structure of each unit in the holographic phase pattern array obtained in step 2, and then perform array stitching on the phase structure of each unit to obtain a holographic phase pattern array.

[0037] Step 4: According to the mode of each sub-beam in the required array beam, set the phase structure of the corresponding phase holographic plate 1; by changing the incident beam of different modes, the array arrangement of the corresponding beam can be obtained.

[0038] Step 5: The Gaussian beam emitted by the laser passes through the phase hologram plate 1, the holographic phase pattern array 2, and the Fourier transform lens 3 in sequence, and an array beam of any arrangement can be obtained in the far field; the output array beam is the convolution of the Fourier transform of the incident beam and the comb function.

[0039] The phase inversion algorithm is the GS phase inversion algorithm, and other phase inversion algorithms may also be used.

[0040] Embodiment: A vortex beam array that generates an “IOE” shaped light field distribution.

[0041] In this embodiment, the optical path diagram for generating a vortex beam array with a specific arrangement is as follows: Figure 1 As shown, the incident light beam passes through the phase holographic plate 1 to obtain a light beam of the corresponding mode, then passes through the holographic phase pattern array 2, and then passes through a Fourier transform lens 3 to achieve Fourier transform and obtain a correspondingly arranged light beam array.

[0042] In this embodiment, a light field distribution in the shape of "IOE" is generated, such as Figure 2 As shown, Figure 2 (a) is the target array intensity distribution diagram, Figure 2 (b) is the phase distribution diagram corresponding to the target array intensity distribution diagram. According to formula (3), the Fourier transform of the phase structure of each unit in the holographic phase pattern array determines the light field distribution of the array beam. Therefore, using the intensity inversion algorithm, the phase distribution diagram corresponding to the target array intensity distribution diagram can be obtained, as shown in Figure 2 According to formula (4), the period of the holographic phase array can be obtained, and finally the holographic phase array is obtained as Figure 3 In this embodiment, the vortex beam array is regulated and generated, so the phase holographic plate 1 is set to a spiral phase structure, such as Figure 4 As shown, Figure 4 Schematic diagram of the phase distribution of the phase hologram that modulates the incident light pattern. After the incident light beam undergoes the spiral phase, its Fourier transform becomes a vortex light beam.

[0043] The incident light beam passes through the phase holographic plate 1 and the holographic phase pattern array 2 in sequence, carrying the corresponding phase structure, and then passes through the Fourier transform lens 3 to achieve Fourier transform, and finally obtains the amplitude modulated vortex beam array with the expected light field distribution in the far field, as shown in FIG. Figure 5 As shown, a vortex beam array with a light field distribution of "IOE" is obtained. Figure 5It is the vortex beam array after amplitude modulation.

[0044] The above embodiments show that the present invention can obtain a two-dimensional array of corresponding light beams of arbitrary arrangement without complex phase control.

[0045] The present invention is not limited to the above-mentioned specific implementation modes. Any modifications and changes to the present invention within the spirit and principle of the present invention should also fall within the protection scope of the claims of the present invention.

Claims

1. A method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect, characterized in that: The steps include: Step 1: Calculate the period of the holographic phase pattern array according to the period of the required array beam based on Fourier transform; Step 2: Calculate the phase structure of each unit in the holographic phase pattern array according to the required intensity distribution of the array beam through the phase inversion algorithm; Step 3: combining the period of the holographic phase image array obtained in step 1 and the phase structure of each unit in the holographic phase image array obtained in step 2, and then performing array splicing on the phase structure of each unit to obtain a holographic phase image array; Step 4: According to the mode of each sub-beam in the required array beam, the phase structure of the phase hologram plate corresponding to the mode is set to modulate the mode of the incident beam; Step 5: The Gaussian beam emitted by the laser passes through the phase holographic plate, the holographic phase pattern array, and the Fourier transform lens in sequence, and an array beam of any arrangement can be obtained in the far field.

2. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 1, characterized in that: In step 2, the phase inversion algorithm is a GS phase inversion algorithm.

3. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 1, characterized in that: In step 2, the Fourier transform of the phase structure of each unit in the holographic phase pattern array determines the light field distribution of the array beam.

4. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 1, characterized in that: In step 2, by modulating the phase structure of each unit in the holographic phase pattern array, arbitrary arrangement of array beam control can be achieved.

5. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 1, characterized in that: In step 1, the two-dimensional array is Fourier transformed as follows: （1） in, represents the Fourier transform, are the rectangular coordinates of the input surface, are the rectangular coordinates of the output surface, is a two-dimensional comb function, is the period of the comb function.

6. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 5, characterized in that: In step 5, when the incident light beam illuminates a holographic phase pattern array, the product of the incident light beam and the holographic phase pattern array is as follows: （2） in, represents the incident light field, represents the transmittance function of the holographic phase pattern array, is the period of the holographic phase pattern array, " " represents convolution, represents a two-dimensional rectangular function, is a two-dimensional comb function, is the phase structure function of each unit in the holographic phase pattern array, i is an imaginary number, is an exponential function.

7. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 6, characterized in that: In step 5, according to optical convolution, after Fourier transform, formula (2) can be regarded as the convolution of the Fourier transform of the incident light beam and the Fourier transform of the array optical element, as follows: （3）。 8. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 1, characterized in that: In step 4, the incident light beams of different modes are changed to obtain the array arrangement of the corresponding light beams.

9. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 1, characterized in that: In step 5, the output array beam is the convolution of the Fourier transform of the incident beam and the comb function.

10. The method for controlling an arbitrarily arranged array of light beams based on an optical convolution effect according to claim 1, characterized in that: In step 1, the relationship between the required array beam and the period of the holographic phase pattern array is expressed as follows: （4） In the above formula, is the period of the array beam, is the period of the holographic phase pattern array, is the laser wavelength, is the focal length of the Fourier transform lens.

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