Optical nonlinear activator based on two-dimensional material-polymer composite film and preparation method and application thereof

Abstract

The invention provides an optical nonlinear activator based on a two-dimensional material-polymer composite film and a preparation method and application thereof, and relates to the technical field of optical nonlinearity. A polymer material and a two-dimensional material are mixed to obtain a two-dimensional material-polymer composite film, and the nonlinear activator is prepared; by utilizing the saturable absorption characteristic of the two-dimensional material-polymer composite film, the nonlinear operation of input and output is completed, a photoelectric conversion process is not needed, the polymer film can be arranged in an optical fiber connector, standard single-mode optical fibers are arranged at the two ends of the polymer film, the polymer film can be directly connected with an existing optical calculation chip, and the coupling structure is simple and easy to implement. The method has flexibility and compatibility, can be used as a nonlinear activation layer of an optical neural network, does not need a photoelectric conversion process, improves the response rate, and reduces the system energy consumption.

Description

Technical Field

[0001] The present invention relates to the field of optical nonlinear technology, and in particular to an optical nonlinear activator based on a two-dimensional material-polymer composite film, and a preparation method and application thereof. Background Art

[0002] With the rapid expansion of data volume, the slowdown of Moore's Law, the miniaturization of transistors approaching the physical limit, and the inherent limitations of electrical response rate, traditional electrical processors are no longer able to pursue high-speed, low-latency data processing. The current computing system is facing the dual challenges of insufficient computing power supply and a widening energy consumption gap. In this context, optical neural networks, with their inherent parallel processing and highly interconnected characteristics, as an outstanding representative in the field of optical computing, provide a highly potential solution to break through the technical bottleneck of the post-Moore era.

[0003] Optical neural networks are composed of linear weighted summation and nonlinear activation units. In terms of linear weighted summation, a variety of mature technologies have emerged in the optical domain, such as Mach-Zehnder interferometer arrays (MZI) and microring resonator arrays (MRR). However, the development of nonlinear activation units is relatively lagging behind. At present, most solutions tend to realize nonlinear activation in the electrical domain, which requires converting optical signals into electrical signals, introducing nonlinear mapping, and finally converting electrical signals back to optical signals. This process requires additional power support, which aggravates the energy consumption problem of the system and fails to give full play to the advantages of optical computing.

[0004] The preparation of optical nonlinear activators that can directly realize nonlinear mapping from optical signal to optical signal in the optical domain without the need for photoelectric conversion and that are compatible with optical chips that perform linear operations remains a technical challenge that needs to be solved urgently. Summary of the invention

[0005] The present invention provides an optical nonlinear activator based on a two-dimensional material-polymer composite film, and a preparation method and application thereof. In the field of optics, a nonlinear activator is constructed. The optical nonlinear activator based on a two-dimensional material-polymer composite film can make full use of the advantages of light, and has the advantages of fast response speed, low energy consumption, etc. It is expected to achieve new breakthroughs in the field of artificial intelligence in the future and inject new impetus into the progress of computer science. In order to reduce the energy consumption of optical neural network operations, reduce the difficulty of the preparation process, and improve the response rate of the nonlinear activator, the present invention proposes an optical nonlinear activator based on a composite film. The activator utilizes the optical properties of nonlinear saturable absorption of a two-dimensional material-polymer composite film, and can realize a nonlinear mapping relationship from input to output in the optical domain. Through the structure of a standard single-mode optical fiber-composite film-standard single-mode optical fiber, the activator can be coupled with an optical computing chip that performs matrix operations, and has versatility and flexibility.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing an optical nonlinear activator based on a two-dimensional material-polymer composite film, comprising the steps of:

[0008] Mixing the polymer with deionized water to obtain a polymer mother solution;

[0009] The two-dimensional material is uniformly mixed in the polymer mother solution to obtain the optical nonlinear activator based on the two-dimensional material-polymer composite film.

[0010] The method for preparing an optical nonlinear activator based on a two-dimensional material-polymer composite film, wherein the step of mixing a polymer with deionized water to obtain a polymer mother solution comprises:

[0011] Deionized water is placed in a beaker cleaned by an ultrasonic cleaner, the beaker is placed on a magnetic stirrer, the temperature of the stirrer is set, polymer powder is added in small amounts and multiple times, and stirred until the solution becomes transparent to obtain a polymer mother solution. Furthermore, the temperature of the stirrer is set at 20-40°C and the stirring time is 20-30 hours.

[0012] The method for preparing the optical nonlinear activator based on the two-dimensional material-polymer composite film, wherein the steps of uniformly mixing the two-dimensional material in the polymer mother solution to prepare the optical nonlinear activator based on the two-dimensional material-polymer composite film include:

[0013] Add the two-dimensional material to a centrifuge tube with a polymer mother liquor, and use an ultrasonic cleaner to fully mix the two-dimensional material and the polymer mother liquor; put the mixed solution into a centrifuge until the two-dimensional material-polymer supernatant is separated; drop the supernatant into a culture dish, and air-dry it naturally to form a film, thereby obtaining a two-dimensional material-polymer composite film. Furthermore, set the centrifuge speed to 4000-5000r / min, the centrifugation time to 10-20 minutes; and let it stand at room temperature for 20-30 hours to air-dry it naturally to form a film.

[0014] The method for preparing an optical nonlinear activator based on a two-dimensional material-polymer composite film, wherein the polymer is one of sodium carboxymethyl cellulose, polyvinyl alcohol, and polymethyl methacrylate.

[0015] The method for preparing an optical nonlinear activator based on a two-dimensional material-polymer composite film, wherein the two-dimensional material is one of graphene, transition metal sulfide, black scale, and transition metal carbide.

[0016] The method for preparing an optical nonlinear activator based on a two-dimensional material-polymer composite film, wherein the concentration of the two-dimensional material-polymer supernatant is 0.4-0.6 mg / ml.

[0017] An optical nonlinear activator based on a two-dimensional material-polymer composite film, the nonlinear activator consists of a polymer material and a two-dimensional material uniformly mixed therein, and is prepared by the method of the present invention.

[0018] An application of an optical nonlinear activator based on a two-dimensional material-polymer composite film, wherein the nonlinear activator based on a two-dimensional material-polymer composite film described in the present invention is used in an optical neural network.

[0019] In summary, the present invention realizes a nonlinear activator in an optical neural network by utilizing the optical nonlinear characteristics of a composite film prepared by uniformly mixing two-dimensional materials and polymers. Compared with the nonlinear activation realized in the electrical domain, it has the characteristics of low energy consumption and fast response speed. It also has the characteristics of simple preparation process, low cost, high flexibility and strong compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of a method for preparing an optical nonlinear activator based on a two-dimensional material-polymer composite film according to the present invention;

[0021] Figure 2 A schematic diagram of the structure of an optical nonlinear activator based on a two-dimensional material-polymer composite film prepared by the present invention;

[0022] Figure 3 The result diagram for measuring the nonlinear activation function based on the composite film;

[0023] Figure 4 It is a schematic diagram of using the optical nonlinear activator based on two-dimensional material-polymer composite film of the present invention for optical neural network;

[0024] Figure 5 This is the accuracy curve calculated on the test data set when using the nonlinear activation function based on composite film. DETAILED DESCRIPTION

[0025] The technical scheme and hardware structure in the embodiments of the present invention will be fully described below in conjunction with the drawings in the embodiments of the present invention. Unless otherwise specifically stated, the relative arrangement of the components and steps described in these embodiments does not limit the scope of the present invention. In order to make the objects, technical schemes and advantages of the present invention more obvious, the exemplary embodiments according to the present invention will be described in detail below with reference to the drawings. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein. Based on the embodiments of the present invention described in the present invention, all other embodiments obtained by those skilled in the art without paying creative work should fall within the protection scope of the present invention.

[0026] Due to the bottleneck of micro-machining technology, the constraints of quantum tunneling effects, and the limitation of copper wire bandwidth, the growth rate of Moore's Law for transistors has gradually slowed down, and electronic neural networks based on the von Neumann system have found it difficult to achieve breakthroughs in computing power and power consumption. Optical neural networks based on optical signals provide new solutions to break through the bottleneck of electronic neural networks due to their advantages such as large bandwidth, ultra-high speed, and low power consumption. However, compared with the mature linear matrix multiplication operation part, the development of the nonlinear activation part of the optical neural network is relatively slow. Most architectures choose to perform nonlinear mapping of signals in the electrical domain, failing to give full play to the advantages of low power consumption and ultra-high speed of optical computing.

[0027] At present, the main methods for realizing all-optical nonlinear activators include tapered optical fibers combined with two-dimensional material suspensions, silicon-based waveguides combined with two-dimensional material suspensions, and femtosecond laser direct writing of two-dimensional material layers on the end face or surface of optical waveguides. However, the preparation processes of these schemes are complicated, making it difficult to promote and industrialize all-optical nonlinear activators.

[0028] Based on this, the present invention provides a method for preparing an optical nonlinear activator based on a two-dimensional material-polymer composite film.

[0029] Embodiment 1, as Figure 1 As shown, the preparation method of the present invention comprises the following steps:

[0030] Step 1: Mix the polymer with deionized water. Specifically, place a beaker containing 100 ml of deionized water on a magnetic stirrer, set the stirrer at 30°C, add polymer powder in small amounts and multiple times while the stirrer is running, and stir for 24 hours until the solution in the beaker becomes transparent, thus forming a polymer mother liquor;

[0031] Step 2: Add the two-dimensional material to the polymer mother liquor. Specifically, 10 ml of the mother liquor is placed in a centrifuge tube, and 5 mg of the two-dimensional material powder is added. At this time, the two-dimensional material and the polymer mother liquor are clearly separated;

[0032] Step 3: Ultrasonic treatment to obtain a two-dimensional material-polymer mixed solution. Specifically, the centrifuge tube described in step 2 is placed in an ultrasonic cleaning machine, and the two-dimensional material and the polymer mother solution are fully mixed through the cavitation effect of the ultrasonic cleaning machine;

[0033] Step 4: Centrifuge to obtain a two-dimensional material-polymer supernatant. Specifically, place the centrifuge tube described in step 3 in a centrifuge, set the centrifuge speed to 4500 r / min, and centrifuge for 15 minutes to obtain a two-dimensional material-polymer supernatant;

[0034] Step 5: Air-drying to form a film. Specifically, the supernatant described in step 4 is dripped onto the surface of a culture dish or a glass slide, and allowed to stand at room temperature for 24 hours. After natural air drying, a two-dimensional material-polymer composite film can be obtained;

[0035] Embodiment 2:

[0036] Different from Example 1, in step 1 of this example, the stirrer is set at 20° C., and the polymer powder is added and stirred for 30 hours until the solution in the beaker becomes transparent;

[0037] In step 2, 10 ml of the mother solution was placed in a centrifuge tube, and 4 mg of the two-dimensional material powder was added;

[0038] In step 4, the centrifuge speed was set to 4000 r / min and the centrifugation time was set to 20 minutes;

[0039] In step 5, the mixture is allowed to stand at room temperature for 30 hours and then naturally dried to obtain a two-dimensional material-polymer composite film;

[0040] Embodiment 3:

[0041] The difference from Example 1 and Example 2 is that in step 1 of this example, the stirrer is set at 40° C., and the polymer powder is added and stirred for 20 hours until the solution in the beaker becomes transparent;

[0042] In step 2, 10 ml of the mother solution was placed in a centrifuge tube and 6 mg of the two-dimensional material powder was added;

[0043] In step 4, the centrifuge speed was set to 5000 r / min and the centrifugation time was set to 10 minutes;

[0044] In step 5, the mixture is allowed to stand at room temperature for 20 hours and then naturally air-dried to obtain a two-dimensional material-polymer composite film;

[0045] The nonlinear activator prepared in the embodiment is tested below. Figure 2As shown, during the test, the optical fiber flange 3 is used to directly fix the composite film 2 between the end faces of the two optical fibers 1, forming a "sandwich" structure of single-mode optical fiber-composite film-single-mode optical fiber. This coupling structure is simple and flexible, easy to couple with the optical chip, and has universality and compatibility.

[0046] The test adopts a dual-channel balanced detection method. The light emitted by the mode-locked pulse laser is divided into two paths of light with the same intensity after passing through a 3dB optical coupler. One path of light is used to record the light intensity before passing through the composite film and is directly detected by an optical power meter. The other path of light first passes through the composite film and then is detected by optical power. After passing through the composite film, part of the light will be absorbed, so the power density of the two paths of light will be different. This is reflected in the different powers measured by the two optical power meters on the optical power meter. By comparison, the corresponding relationship between the transmittance (T) of the composite film and the input light intensity (I) can be obtained. This relationship can be described by the saturable absorption model of the two-dimensional quantum well: Where α0 is the linear absorption coefficient, I s is the saturation intensity, I is the intensity of the incident light, α(I) is the total absorption coefficient, and the output light intensity after the material is expressed as: I out As a function of I, taking the derivative with respect to I, we get: This formula proves the feasibility of the composite film as a nonlinear activator. The test results are as follows Figure 3 As shown, it can be seen that with the increase of light intensity, the transmittance of the nonlinear activator based on the two-dimensional material-polymer composite film gradually increases, and this curve is used as the nonlinear activation function of the nonlinear activator.

[0047] In order to verify the feasibility of applying the nonlinear activator based on two-dimensional material-polymer composite film to optical neural network, the nonlinear activator was put into the optical neural network for simulation, such as Figure 4 As shown, the optical neural network includes an optical interference unit (OIU) composed of an MZI array and an optical nonlinear unit (ONU) based on a two-dimensional material-polymer composite film. The MNIST handwritten digit classification task was selected as the test platform. The MNIST handwritten digit dataset contains a benchmark dataset of 70,000 handwritten digit grayscale images. Each image has been center-aligned and size-normalized to a single-channel image of 28×28 pixels. The dataset covers 10 digital categories from 0 to 9, of which 60,000 samples are used as training sets, and the remaining 10,000 samples are used as test sets to evaluate the generalization ability of the model. The final training results are shown in Figure 5 As shown, after training, the recognition accuracy of the neural network can reach more than 90%.

[0048] The above description of the specific implementation is intended to describe and illustrate the technical solution of the present invention, and the above specific implementation is only illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, ordinary technicians in this field can also make many forms of specific changes under the enlightenment of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing an optical nonlinear activator based on a two-dimensional material-polymer composite film, characterized in that: Includes steps: Mixing the polymer with deionized water to obtain a polymer mother solution; Uniformly mixing the two-dimensional material in the polymer mother solution to obtain the optical nonlinear activator based on the two-dimensional material-polymer composite film; The step of mixing the polymer with deionized water to obtain a polymer mother solution comprises: Put deionized water in a beaker cleaned by an ultrasonic cleaner, place the beaker on a magnetic stirrer, set the temperature of the stirrer, add polymer powder in small amounts and multiple times, and stir until the solution becomes transparent to obtain a polymer mother solution; The steps of uniformly mixing the two-dimensional material in the polymer mother solution to prepare the optical nonlinear activator based on the two-dimensional material-polymer composite film include: The two-dimensional material is added into a centrifuge tube containing a polymer mother solution, and the two-dimensional material and the polymer mother solution are fully mixed by an ultrasonic cleaning machine; The mixed solution is placed in a centrifuge until the two-dimensional material-polymer supernatant is separated; The supernatant was added dropwise to a culture dish and naturally air-dried to form a film, thereby obtaining a two-dimensional material-polymer composite film.

2. The preparation method according to claim 1, characterized in that: The polymer is one of sodium carboxymethyl cellulose, polyvinyl alcohol and polymethyl methacrylate.

3. The preparation method according to claim 1, characterized in that: The two-dimensional material is one of graphene, transition metal sulfide, black scale and transition metal carbide.

4. The preparation method according to claim 1, characterized in that: The concentration of the two-dimensional material-polymer supernatant is 0.4-0.6 mg / ml.

5. The preparation method according to claim 1, characterized in that: Set the mixer temperature to 20-40°C and the mixing time to 20-30 hours.

6. The preparation method according to claim 1, characterized in that: Set the centrifuge speed to 4000-5000r / min and the centrifugation time to 10-20 minutes; let it stand at room temperature for 20-30 hours to naturally air-dry to form a film.

7. An optical nonlinear activator based on a two-dimensional material-polymer composite film, characterized in that: The nonlinear activator comprises a polymer material and a two-dimensional material uniformly mixed therein, and is prepared by the method described in any one of claims 1-6.

8. The use of the optical nonlinear activator based on the two-dimensional material-polymer composite film according to claim 7, characterized in that: The nonlinear activator based on two-dimensional material-polymer composite film is used in optical neural networks.

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