All-optical logic operation system and operation method based on metasurface device

Abstract

The application discloses a kind of full light logic operation system and operation method based on super surface device, mainly solve the system complexity of existing optical logic gate is high, judgment result is not enough intuitive, identification difficulty is big, practicality is poor and other technical problems.The logic operation system includes the polarization plate, object plane, super surface device and detector arranged in sequence;Polaroid is used to adjust the polarization direction of incident light;Object plane is provided with a plurality of different shapes and transparent target areas, for placing corresponding target image;The center of all target areas is distributed on the circle with the center of object plane as the center, d Incident light reaches super surface device after polarization plate and target image on object plane, carries out optical logic operation by super surface device, and then outputs to detector imaging.The application has the advantages of simple structure, rapid function switching, miniaturization, high integration, etc.

Description

TECHNICAL FIELD

[0001] The present application relates to optical logic operation, in particular to a full-optical logic operation system and operation method based on a metasurface device. BACKGROUND

[0002] Electronic logic operation system has the characteristics of fast processing speed, low crosstalk, high throughput, etc., but with the rapid growth of information processing demand, the traditional electronic logic operation system gradually shows bottleneck in power consumption, parallel processing capability and storage-computing integration, etc. Optical logic operation system as an important part of optical digital computing lays the foundation for realizing optical computer and optical quantum computer. Compared with the traditional electronic logic operation system, the optical digital computing of optical logic operation system has the advantages of low power consumption, high speed, high parallelism, high degree of freedom, no need for heat dissipation, etc. Not only overcomes the problems of high energy consumption and poor parallelism of electronic logic operation system, but also retains its high precision and versatility, so it has important research significance and application potential.

[0003] The existing optical logic operation system mainly relies on electrically controlled optical mechanism, which is still limited by electronic control system in essence, and it is difficult to fully play the unique advantages of full-optical logic operation system in high-speed parallel processing. Therefore, developing a full-optical logic operation system based on "light-controlled light" becomes a more efficient and promising scheme. Full-optical logic operation system can be realized through various physical mechanisms, including nonlinear optical effects, semiconductor optical amplifiers, on-chip waveguide devices, and the metasurface device which has attracted much attention in recent years.

[0004] The metasurface device is composed of an array of nanometer structures with subwavelength scale, which can locally control the phase, amplitude and polarization state of incident light. With its excellent light field regulation ability and structural design flexibility, the metasurface device can replace traditional optical elements (such as lenses, beam splitters, etc.), realize optical computing functions, and greatly reduce the size of the optical logic operation system, which meets the current development trend of miniaturization and integration of optical platforms. Therefore, the metasurface device has high flexibility and diversity in designing optical computers. Different materials, shapes and sizes of metasurface devices can be used to realize optical computing devices based on different principles and architectures, and then realize logic operation, integration, differentiation and other mathematical operations.

[0005] A kind of optical logic gate based on super surface is disclosed in Chinese invention patent with publication number CN111045274A, incident light is sequentially through polarizer, super surface, analyser and then exit, the polarization direction of polarizer and the polarization direction of analyser are used as the input of logic gate, and the light intensity of exit light is used as the output of logic gate.The polarization direction of the polarizer and the analyser of the optical logic gate needs to be accurately set as the logic input, but in actual application, small polarization error can cause calculation error;And after polarization direction is determined, precise calibration is also needed, thereby increasing the complexity of the system.In addition, the optical logic gate uses exit light intensity as logic output, and the judgment result is not intuitive.

[0006] For example, Chinese invention patent with publication number CN117970634A discloses a design method, device, medium and product of all-optical controllable logic gate based on super lens, which constructs all-optical controllable logic gate with multiple super lenses as light input end, uses light interference effect, focuses the exit light of the same phase or opposite phase to transmission focal point through super lens, and then determines the logic state by detecting the light intensity at transmission focal point and comparing it with threshold value.For example, when the light input of two same phase ends is controlled, logic "and" operation can be realized;When the light input of two same phase ends and one opposite phase end is controlled, logic "XOR" operation can be realized.However, this method needs multiple super lenses to realize logic operation, and the operation result needs to be judged in combination with the comparison result of light intensity at transmission focal point and threshold value, thereby increasing the identification difficulty and reducing the rate of logic operation.

[0007] For example, Chinese invention patent with publication number CN118378677A discloses a dual-polarization multiplexing electromagnetic super surface logic operator, which obtains different focusing focal points by changing the incident wave entering the dual-polarization super surface, and uses them to represent different operation results, thereby realizing the function of logic operation and applying it to electromagnetic wave diffraction calculation and other application scenarios.However, the way of judging logic operation by focusing focal point still needs to detect the position of focusing focal point, which cannot directly display the result of logic operation, thereby limiting its practicality. SUMMARY

[0008] The present application aims to solve the technical problems of high system complexity, non-intuitive judgment result, large identification difficulty and poor practicality of existing optical logic gate, and provides an all-optical logic operation system and operation method based on super surface device.

[0009] To achieve the above-mentioned purpose, the technical solution provided by the present application is as follows:

[0010] An all-optical logic operation system based on super surface device, characterized in that it comprises a polarizer, an object plane, a super surface device and a detector arranged in sequence.

[0011] The polarizer is used for adjusting the polarization direction of incident light.

[0012] The object plane is provided with a plurality of transparent target regions with different shapes for placing corresponding target images; the centers of all target regions are distributed on a circle with the center of the object plane as the center and d as the radius, wherein, P is the period of the metasurface device, f is the focal length of the metasurface device, is the wavelength of the incident light; the incident light passes through the polarizer and the target image on the object plane in turn and then reaches the metasurface device;

[0013] The metasurface device is used for performing optical logic operation on the incident light passing through the target image and outputting to a detector, and the detector is used for realizing imaging of the target image.

[0014] Further, the metasurface device has periodicity, which includes a substrate and a plurality of nanometer columns arranged in an array on the substrate; the side of the substrate far from the nanometer columns is connected with a detection surface of the detector and is adapted to the size of the detection surface; the plurality of nanometer columns are arranged on the substrate according to the metasurface transmission phase principle and are used for providing corresponding target phases to realize all-optical logic operation.

[0015] Further, the phase delay of the metasurface device is determined in the following manner:

[0016]

[0017] In the formula, represents the transmission phase of the metasurface device, and the transmission phase covers 0~2π, n eff is the effective refractive index of the metasurface device, H1 is the height of the nanometer column, and λ is the wavelength of the incident light.

[0018] Further, the arrangement of the nanometer column is expressed by using the phase distribution function of the metasurface device, that is,

[0019]

[0020]

[0021] wherein, represents the target phase when the incident light is X-polarized light, represents the target phase when the incident light is Y-polarized light, (x, y) represents the position coordinates of the metasurface device; v represents the frequency of the metasurface device; j represents the imaginary unit; k represents the wave number of the incident light wavelength; 2f represents the double focal length of the metasurface device, which refers to the distance between the object plane and the end of the nanometer column far from the substrate.

[0022] Further, the substrate is made of silicon dioxide, and the nanometer column is made of silicon nitride.

[0023] Further, the target region has two target image placement areas, one of which is a to-be-recognized or to-be-detected image, and the other is a contrast image, and the centers of the two are located on both sides of the center of the object plane and are located on the same straight line as the center of the object plane.

[0024] Meanwhile, the application also provides a kind of full light logic operation method based on super surface device, comprising the following steps:

[0025] Step 1: assemble the full light logic operation system based on super surface device described above, and place the target image on the corresponding target region on the object plane;

[0026] Step 2: adjust the polarization direction of incident light by polaroid, and the incident light reaches the super surface device in turn after passing through polaroid and the target image on the object plane;The polarization direction includes X polarization and Y polarization;

[0027] Step 3: the incident light passing through the target image is optically logically operated by the super surface device, and is output to the detector imaging, so as to realize the full light logic operation based on super surface device.

[0028] Further, in step 2, the light field of incident light reaching the super surface device after passing through the target image on the object plane is :

[0029]

[0030] In the formula, Indicates the light field of incident light reaching the object plane; Indicates the position coordinates of the corresponding target image on the object plane;(x,y) indicates the position coordinates of the super surface device;j indicates the imaginary unit;λ indicates the wavelength of incident light;k indicates the wave number of incident light wavelength;2f indicates the double focal length of the super surface device, which refers to the distance between the object plane and the end of the nanometer column away from the substrate.

[0031] Further, in step 3, the optical logic operation is AND operation or XOR operation, when the incident light is X polarized light, AND operation is carried out;When the incident light is Y polarized light, XOR operation is carried out.

[0032] Further, in step 3, the light field on the imaging surface of the detector Indicates as follows:

[0033]

[0034] In the formula, Indicates the corresponding target phase, Position coordinates of the target image on the imaging surface of the detector.

[0035] Compared with the prior art, the present application has the following advantages:

[0036] 1. The all-optical logic operation system based on the metasurface device, comprising a polarizer, an object plane, a metasurface device and a detector arranged in sequence, wherein the polarizer is used to adjust the polarization direction of the incident light, the object plane is used to carry the target image, and the metasurface device is used to perform optical logic operation on the incident light passing through the target image and output to the detector imaging.

[0037] 2. The all-optical logic operation system based on the metasurface device has integrated functions, can directly perform optical logic processing on any two images, and can directly display the logic operation results on the imaging surface of the detector without additional auxiliary optical elements (such as lenses).

[0038] 3. The all-optical logic operation system based on the metasurface device can realize multi-channel simultaneous logic operation by designing an array type nano column arrangement structure that produces specific logic function response to different polarization state incident light, and has good application prospect in the fields of image recognition, difference detection and medical image analysis.

[0039] 4. The all-optical logic operation method based on the metasurface device can detect the differences between multiple images, and can be applied to image recognition and detection of medical lesion sites.

[0040] 5. The all-optical logic operation method based on the metasurface device can output clear and distinguishable logic AND operation and XOR operation results, and further facilitate intuitive extraction of the similarity and difference between multiple images. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a structural schematic diagram of an embodiment of the all-optical logic operation system based on the metasurface device of the present application.

[0042] Figure 2 is a structural schematic diagram of the metasurface device in the embodiment of the all-optical logic operation system based on the metasurface device of the present application.

[0043] Figure 3 is a phase distribution diagram in an embodiment of the all-optical logic operation method based on the metasurface device of the present application, wherein (a) is the phase distribution diagram of AND operation, and (b) is the phase distribution diagram of XOR operation.

[0044] Figure 4 This is an example of optical logic operation and two operation results in an embodiment of the all-optical logic operation method based on metasurface devices of the present invention.

[0045] Figure 5 This is a schematic diagram of the XOR operation in an image recognition application of an embodiment of the all-optical logic operation system based on metasurface devices of the present invention.

[0046] The attached figures are labeled as follows:

[0047] 1-Object plane, 2-Metasurface device, 21-Substrate, 22-Nanopillar, 3-Detector. Detailed Implementation

[0048] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0049] like Figure 1 As shown, this embodiment provides an all-optical logic operation system based on metasurface devices, including polarizers arranged sequentially ( Figure 1 (Not shown in the image), object plane 1, metasurface device 2, and detector 3.

[0050] Polarizers are used to adjust the polarization direction of incident light, that is, to adjust the incident light to X-polarized light or Y-polarized light according to the calculation requirements.

[0051] In this embodiment, two transparent target regions of different shapes are provided on the object plane 1. One is triangular, and the other is rectangular, used to place target images A and B of corresponding shapes, respectively. Of course, the shapes of the target regions can also be designed according to actual needs. The distance d between the center of each target region and the center of the object plane 1 is the same, and they are located on the same straight line as the center of the object plane 1. The coordinates of the two target images on the object plane 1 are defined as A(d,0) and B(-d,0), respectively, and the distance between their centers is 2d. P is the period of metasurface device 2; f is the focal length of metasurface device 2. It is the wavelength of the incident light. The purpose of this design is to ensure that the images of the two target images can interfere after passing through the metasurface device 2, so that they overlap at the center position on the output plane of the metasurface device 2, and perform the corresponding optical logic operations.

[0052] The embodiment selects a helium-neon laser to emit incident light with a wavelength of 632.8 nm. The incident light passes through a polarizer and a target image on the object plane 1 in turn and reaches the metasurface device 2. The metasurface device 2 is used to perform optical logic operation on the incident light passing through the target image. The optical logic operation is spatial frequency filtering of the incident light passing through the target image based on the polarization multiplexing characteristics of the metasurface device 2, thereby realizing AND operation or XOR operation. The incident light modulated by the metasurface device 2 continues to propagate and interfere, and finally forms a logic operation result image on the imaging surface of the detector 3, completing the imaging of the target image, and thereby realizing the rapid extraction of the similarity and difference between images.

[0053] The metasurface device 2 of the embodiment has periodicity, which includes a transparent substrate 21 and a plurality of nanometer columns 22 arranged in an array on the substrate 21. The substrate 21 of the embodiment is a rectangular sheet structure, and the nanometer column 22 is a cubic structure with a cross-sectional length L and a width W. The side of the substrate 21 away from the nanometer column 22 is connected to the detection surface of the detector 3 and is adapted to the size of the detection surface; the plurality of nanometer columns 22 are arranged on the substrate 21 according to the super surface transmission phase principle, for providing corresponding target phases to realize optical logic operation.

[0054] Phase delay of the metasurface device 2 It is determined in the following way:

[0055]

[0056] In the formula, represents the transmission phase of the metasurface device 2; n eff is the effective refractive index of the metasurface device 2, which is determined by the length L and the width W of the nanometer column 22. By changing the length L and the width W of the nanometer column 22, the transmission phase covers 0~2π; represents the height of the nanometer column 22, which is 700 nm in the embodiment, and λ is the wavelength of the incident light, which is 632.8 nm.

[0057] The arrangement of the nanometer column 22 (i.e. the target phase) is represented by the phase distribution function of the metasurface device 2, that is:

[0058]

[0059]

[0060] wherein, represents the target phase when the incident light is X-polarized light, represents the target phase when the incident light is Y-polarized light, (x, y) represents the position coordinates of the metasurface device 2; v represents the frequency of the metasurface device 2; j represents the imaginary unit; k represents the wave number of the incident light wavelength; f represents the focal length of the metasurface device 2, and 2f represents the double focal length of the metasurface device 2, which is a 2f system, that is, the distance between the end of the nanorod 22 far from the substrate 21 and the object plane 1 is 2f, and the distance between the nanorod 22 and the detector is also 2f. Using the 2f system, no additional optical elements such as lenses are needed to assist, so that the structure of the operation system is more simple.

[0061] In this embodiment, the Finite-Difference Time-Domain (FDTD) method is used to model and simulate the metasurface device 2 based on the metasurface transmission phase principle, Figure 2 Fig. 4 is a schematic view of a local structure of the metasurface device 2, wherein P is the period of the metasurface device 2, H1 is the height of the nanorod 22, and H2 is the thickness of the substrate 21. Taking the case of vertical incidence of the light beam as an example, in the FDTD simulation, the incident light has a phase delay after passing through the metasurface device 2, and the phase delay is the phase accumulation realized by the propagation of the light in the microstructure with a high aspect ratio. After sampling and selection, the material of the nanorod 22 and the substrate 21 is finally determined to be silicon nitride and silicon dioxide respectively, the period P is 350 nm, and the thickness H1 is 700 nm. Of course, the specific parameters can also be designed according to the requirements of time operation.

[0062] In this embodiment, the bottom surface of the nanorod 22 is scanned in the range of 0.2P~0.8P with a scanning interval of 1 nm, and the phase delay and the relationship between the length and width of the nanorod 22; and the two nanorods 22 with different lengths and widths selected according to the above phase distribution function are arranged, so that the polarization multiplexing metasurface device 2 is obtained.

[0063] As can be seen from the above, the cosine grating (i.e. the metasurface device 2) used for the target phase required for logical operation is determined by the different initial phases of the binary phase grating to determine the phase distribution of the metasurface design under the working wavelength channel, that is, the cosine grating with an initial phase of 0 can perform AND operation, and the cosine grating with an initial phase of π / 2 can perform XOR operation. Therefore, the polarization multiplexing characteristics of the metasurface device 2 can perform AND operation and XOR operation.

[0064] The application does not rely on additional optical elements such as lenses, has a simple structure, rapid function switching, significantly improves the multifunctionality and practicality of the logic operation system, and simplifies the overall design and manufacturing process. As a full-optical logic operation system, the system can not only complete multiple logic operations in parallel, but also has high-speed operation capability, and is suitable for application scenarios such as image recognition, image encryption, medical image analysis, etc. In addition, the metasurface device 2 is composed of a nano structure array with a subwavelength scale, has the advantages of easy integration, miniaturization, high flexibility, etc., and is very consistent with the trend of miniaturization and integration of contemporary optical platforms, making it an ideal basic platform for building the next generation of full-optical image processors.

[0065] The embodiment also provides a full-optical logic operation method based on a metasurface device, comprising the following steps:

[0066] Step 1: Assemble the full-optical logic operation system based on the metasurface device described in the embodiment, and place the target images on the corresponding target regions on the object plane 1.

[0067] Step 2: Adjust the polarization direction of the incident light through the polarizer, then the incident light reaches the metasurface device 2 in turn after passing through the polarizer and the target images on the object plane 1; the polarization direction includes X polarization and Y polarization.

[0068] According to Fresnel diffraction, the light field of the incident light reaching the metasurface device 2 after passing through the target images on the object plane 1 is represented as:

[0069]

[0070] In the formula, E(x,y) represents the light field of the incident light reaching the object plane 1; represents the position coordinates of the corresponding target image on the object plane 1.

[0071] Step 3: Perform optical logic operation on the incident light passing through the target images through the metasurface device 2, the optical logic operation is AND operation or XOR operation, when the incident light is X polarized light, the target phase is , at this time, AND operation is performed; when the incident light is Y polarized light, the target phase is , at this time, XOR operation is performed, then imaging is completed through the detector 3, thereby realizing full-optical logic operation based on the metasurface device.

[0072] The light field on the imaging surface of the detector 3 is represented as:

[0073]

[0074] In the formula, E(x,y) represents the light field of the incident light reaching the object plane 1; represents the corresponding target phase, that is​​​ or , represents the position coordinate of the target image on the imaging surface of the detector 3.

[0075] Figure 3 and Figure 4 The phase distribution diagrams of the super surface device 2 used for logical and operation and exclusive or operation, and the corresponding optical logical operation result diagrams are drawn respectively, by Figure 3 and Figure 4 The ability of the super surface device 2 to perform full-optical logical operation on different input images can be intuitively shown.

[0076] Logical operation, as one of the basic tasks of optical image processing, has a wide range of applications in detecting the differences between two images, especially in identifying the lesion area in medical images and comparing images of different time periods. At the same time, exclusive or operation is particularly common in the field of image recognition.

[0077] Figure 5 The exclusive or operation of the full-optical logical operation system based on the super surface device in the image recognition of the embodiment is shown, and the operation result verifies the effectiveness and feasibility of the logical operation system of the embodiment in actual image processing tasks.

[0078] The present application uses a single super surface device to achieve efficient full-optical logical operation. In the digital era, the speed requirement for image and data processing is getting higher and higher. Using electronic components for information processing not only consumes a lot of time, but also cannot improve the processing speed. Optical digital calculation based on optical logical operation system has the advantages of low power consumption, high speed, high parallelism, high degree of freedom, etc., solves the problems of high power consumption, poor parallelism, storage and calculation separation, etc. in electronic logical operation system, while maintaining the high precision and versatility of electronic logical operation system, and has important research and application value. Full-optical logical operation based on light control is a more efficient way. As a two-dimensional metamaterial, super surface has low energy consumption, easy to manufacture, and has the ability of optical calculation, and can be used as an image processor.

[0079] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or part or all of the technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the protection scope of the present application.

Claims

1. An all-optical logic operation system based on metasurface devices, characterized in that: It includes a polarizer, an object plane (1), a metasurface device (2), and a detector (3) arranged in sequence; The polarizer is used to adjust the polarization direction of the incident light; The object plane (1) has multiple transparent target regions of different shapes for placing corresponding target images; the centers of all target regions are evenly distributed on a circle with the center of the object plane (1) as the center and d as the radius, where, P is the period of the metasurface device (2), and f is the focal length of the metasurface device (2). The wavelength of the incident light is denoted as λ. After passing through the polarizer and the target image on the object plane (1) in sequence, the incident light reaches the metasurface device (2). The metasurface device (2) is used to perform optical logic operations on the incident light passing through the target image and output it to the detector (3). The detector (3) is used to realize the imaging of the target image.

2. The all-optical logic operation system based on metasurface devices according to claim 1, characterized in that: The metasurface device (2) is periodic and includes a substrate (21) and a plurality of nanopillars (22) arranged in an array on the substrate (21). The side of the substrate (21) away from the nanopillars (22) is connected to the detection surface of the detector (3) and is adapted to the size of the detection surface. The plurality of nanopillars (22) are arranged on the substrate (21) according to the metasurface phase transfer principle to provide the corresponding target phase for realizing all-optical logic operation.

3. The all-optical logic operation system based on metasurface devices according to claim 2, characterized in that: Phase delay of the metasurface device (2) Determined in the following ways: ； In the formula, This represents the transmission phase of the metasurface device (2), and the transmission phase covers 0~2π, n eff H1 is the effective refractive index of the metasurface device (2), and H1 is the height of the nanopillar (22).

4. The all-optical logic operation system based on metasurface devices according to claim 3, characterized in that: The arrangement of the nanopillars (22) is represented by the phase distribution function of the metasurface device (2), that is: ； ； in, This indicates the target phase when the incident light is X-polarized. The target phase is represented when the incident light is Y-polarized light. (x,y) represents the position coordinates of the metasurface device (2). v represents the frequency of the metasurface device (2). j represents the imaginary unit. k represents the wavenumber of the incident light wavelength. 2f represents twice the focal length of the metasurface device (2), which refers to the distance between the object plane (1) and the end of the nanopillar (22) away from the substrate (21).

5. The all-optical logic operation system based on metasurface devices according to claim 4, characterized in that: The substrate (21) is made of silicon dioxide, and the nanopillars (22) are made of silicon nitride.

6. The all-optical logic operation system based on metasurface devices according to any one of claims 1 to 5, characterized in that: There are two target areas, which are used to place target images. One is the image to be identified or detected, and the other is the comparison image. The centers of the two are located on both sides of the center of the object plane (1) and are on the same straight line as the center of the object plane (1).

7. A method for all-optical logic operation based on metasurface devices, characterized in that, Includes the following steps: Step 1: Assemble the all-optical logic operation system based on metasurface devices as described in any one of claims 1 to 6, and place the target image on the corresponding target area on the object plane (1); Step 2: Adjust the polarization direction of the incident light by means of a polarizer. The incident light passes through the polarizer and the target image on the object plane (1) in sequence before reaching the metasurface device (2). The polarization direction includes X polarization and Y polarization. Step 3: Perform optical logic operations on the incident light passing through the target image using the metasurface device (2) and output the results to the detector (3) for imaging, thereby realizing all-optical logic operations based on the metasurface device.

8. The all-optical logic operation method based on metasurface devices according to claim 7, characterized in that: In step 2, the light field when the incident light passes through the target image on the object plane (1) and reaches the metasurface device (2) for: ； In the formula, This represents the light field when the incident light reaches the object plane (1); (x,y) represents the position coordinates of the corresponding target image on the object plane (1); (x,y) represents the position coordinates of the metasurface device (2); j represents the imaginary unit; λ represents the wavelength of the incident light; k represents the wavenumber of the incident light wavelength; 2f represents twice the focal length of the metasurface device (2), which refers to the distance between the object plane (1) and the end of the nanopillar (22) away from the substrate (21).

9. The all-optical logic operation method based on metasurface devices according to claim 8, characterized in that: In step 3, the optical logic operation is either an AND operation or an XOR operation. When the incident light is X-polarized light, an AND operation is performed; when the incident light is Y-polarized light, an XOR operation is performed.

10. The all-optical logic operation method based on metasurface devices according to claim 9, characterized in that: In step 3, the light field on the imaging surface of the detector (3) Represented as: ； In the formula, Indicates the corresponding target phase. This indicates the position coordinates of the target image on the imaging surface of the detector (3).

Images