An optical encryption method based on cross-correlation liquid crystal planar device

Abstract

The present application belongs to the field of optical encryption and information security technology, and discloses an optical encryption method based on cross-correlation liquid crystal planar device, aiming at solving the problems of limited information capacity, single encryption dimension, low security level and insufficient flexibility of existing liquid crystal optical encryption technology. Firstly, based on the angular spectrum diffraction theory and the gradient descent algorithm, a near-far field target pattern joint optimization model is constructed to realize the collaborative optimization of near-far field image generation parameters; three random phases are selected as the initial phases of the three liquid crystal planar devices and simulation verification is completed; then, the position multiplexing and polarization multiplexing mechanism are introduced for secondary optimization, and the Jones matrix is integrated and used to complete the third optimization by using its non-commutativity, realizing the generation of multiple images under different combination modes of single, double and three liquid crystal devices. The present application greatly improves the information capacity, enriches the encryption dimension, enhances the security, flexibility and expansibility of the encryption system, ensures the clarity and stability of image generation, has high integration and strong practicability, and can be widely applied in the fields of information storage, secure communication, identity authentication and the like.

Description

Technical Field

[0001] This invention belongs to the field of optical encryption and information security technology, specifically relating to an optical encryption method based on a cross-correlation liquid crystal planar device. It is particularly suitable for realizing optical encryption scenarios with multiple scenarios, high capacity, and high security by utilizing the light modulation characteristics, multiplexing technology, and matrix characteristics of liquid crystal devices. It can be widely used in fields such as information storage, secure communication, and identity authentication. Background Technology

[0002] In the digital age, information security issues are becoming increasingly prominent, posing a serious threat to personal privacy, business operations, and national security. Optical encryption technology, with its advantages of high parallelism, fast processing speed, large information capacity, and strong resistance to cracking, has become an important research direction in the field of information security. Among them, liquid crystal planar devices are widely used in optical encryption systems due to their strong tunability, high integration, and low power consumption. By controlling the orientation of liquid crystal molecules, the phase, amplitude, polarization, and other parameters of incident light can be modulated, thereby completing the encryption and decryption of information.

[0003] Currently, optical encryption technology based on liquid crystal devices has made some progress. Some technologies achieve image generation and encryption by stacking single or multiple liquid crystal devices. However, existing technologies still have significant shortcomings: First, the information capacity of traditional liquid crystal optical encryption technology is limited. A single liquid crystal device can only generate a small number of images, and the number of images generated when multiple devices are stacked is still insufficient to meet the requirements of high-capacity encryption. Second, existing technologies lack effective reuse mechanisms and structural designs, failing to fully utilize the control potential of liquid crystal devices. The encryption dimension is singular, resulting in low security of the encryption system and vulnerability to cracking. Furthermore, most technologies do not consider the impact of the stacking order of liquid crystal devices, failing to achieve more diverse encryption effects through stacking order control, further limiting the application scenarios and security levels of optical encryption methods. Simultaneously, the optimization algorithms for near-field and far-field target patterns in existing optical encryption methods are not perfect, making it difficult to achieve coordinated control of near-field and far-field images, resulting in insufficient image clarity and stability. Moreover, when multiple liquid crystal devices work together, there is a lack of effective theoretical support and algorithm optimization, failing to fully leverage the advantages of multi-device collaboration, resulting in poor flexibility and scalability of the encryption system. Therefore, developing an optical encryption method that can increase information capacity, enrich encryption dimensions, and improve security level has become an urgent technical problem to be solved in this field.

[0004] To address the shortcomings of existing optical encryption technologies based on liquid crystal devices, such as limited information capacity, single encryption dimension, low security level, and insufficient flexibility, this invention provides an optical encryption method based on cross-correlation liquid crystal planar devices. By optimizing algorithm design, introducing a reuse mechanism, and utilizing matrix characteristics, it achieves high-capacity and high-security optical encryption in multiple scenarios, promoting the development of multiple fields such as information storage, secure communication, and identity authentication. Summary of the Invention

[0005] To address the shortcomings of existing optical encryption technologies based on liquid crystal devices, such as limited information storage capacity and low encryption performance, this invention provides an optical encryption method based on cross-correlation liquid crystal planar devices. The core of this method lies in achieving multi-image generation of liquid crystal devices under different combination methods through algorithm optimization, the introduction of reuse mechanisms, and the utilization of matrix characteristics. The specific technical solution is as follows: S1. Based on angular spectrum diffraction theory and gradient descent algorithm, a joint optimization model for near-field and far-field target patterns is constructed to collaboratively optimize the generation parameters of near-field and far-field images, ensuring the clarity and stability of image generation. Angular spectrum diffraction theory is used to describe the propagation law of light and provides theoretical support for the generation of far-field images. Gradient descent algorithm is used to iteratively optimize the image generation parameters and minimize the deviation between near-field and far-field images and target patterns. S2. Select three random phases as the initial phases of the three liquid crystal planar devices. Based on the optimization model constructed in step S1, conduct simulation verification to realize that when a single liquid crystal device is working, the three liquid crystal devices independently generate a far-field image and a near-field image. When two liquid crystal devices are stacked, any two liquid crystal devices (liquid crystal device 1 and liquid crystal device 2, liquid crystal device 1 and liquid crystal device 3, liquid crystal device 2 and liquid crystal device 3) can generate an image after being stacked. S3. A reuse mechanism is introduced into the optimization algorithm in step S1, including position reuse and polarization reuse. Position reuse is achieved by setting three different position parameters (d1, d2, d3), and polarization reuse is achieved by using two illumination methods: left-handed circularly polarized light and right-handed circularly polarized light. Secondary optimization is performed by combining angular spectrum diffraction theory and gradient descent algorithm. Simulation verification shows that when a single liquid crystal device is working, the three liquid crystal devices still independently generate a far-field image and a near-field image respectively; when two liquid crystal devices are stacked, any two liquid crystal devices can generate six images after being stacked. S4. In the optimization algorithm of step S3, a Jones matrix is ​​introduced. Utilizing the non-commutativity of the Jones matrix (i.e., the results of matrix multiplication in different orders are different), combined with position multiplexing and polarization multiplexing mechanisms, three optimizations are performed. Simulation verification shows that: when a single liquid crystal device is working, the three liquid crystal devices independently generate a far-field image and a near-field image; when two liquid crystal devices are stacked, any two stacked liquid crystal devices can generate six images; when three liquid crystal devices are stacked, three different holographic images can be generated according to the different stacking orders of the three liquid crystal devices, further enriching the encryption dimension and information capacity.

[0006] Beneficial effects Compared with the prior art, the present invention has the following significant advantages: (1) Information capacity is greatly improved: By introducing position multiplexing and polarization multiplexing mechanisms and combining the non-commutativity of the Jones matrix, multiple image generation is realized when multiple liquid crystal devices are stacked. When two devices are stacked, each pair of devices can generate six images. When three devices are stacked, three different holographic images can be generated according to the order. Compared with traditional technology, the information capacity is increased by orders of magnitude, which can meet the high-capacity encryption requirements. (2) Rich encryption dimensions and high security level: This invention integrates multiple encryption dimensions such as near-field and far-field coordinated control, position multiplexing, polarization multiplexing, and stacking order control. It also increases the encryption complexity by utilizing the non-commutativity of the Jones matrix, making it difficult for illegal crackers to obtain encrypted information through a single dimension of cracking. This significantly improves the security of the encryption system and can effectively cope with complex information security threats. (3) High flexibility and scalability: This invention can realize the flexible combination of single, double and triple liquid crystal devices. Different combination methods correspond to different image generation effects. Furthermore, the encryption scheme can be flexibly adjusted by adjusting position parameters, polarization state, stacking order, etc. It has high scalability and is suitable for a variety of encryption scenarios. (4) Stable image generation effect: Through the joint optimization of angular spectrum diffraction theory and gradient descent algorithm, the coordinated control of near and far field target patterns is realized, ensuring the clarity and stability of the generated image, and providing a guarantee for the accurate transmission and restoration of encrypted information; (5) High integration and strong practicality: The liquid crystal planar device is used as the core encryption unit, which has the characteristics of small size, high integration and low power consumption. The entire technical solution is feasible based on simulation verification and is easy to implement in subsequent engineering. It can be widely used in multiple fields such as information storage, secure communication and identity authentication. Attached Figure Description

[0007] Figure 1 The results are simulations of near-field and far-field images of a cross-correlation liquid crystal device.

[0008] Figure 2Simulation results for a cross-correlation liquid crystal device combined with traditional multiplexing methods.

[0009] Figure 3 Simulation results for cross-correlation liquid crystal devices that combine traditional multiplexing methods with the non-commutativity of the Jones matrix. Detailed Implementation

[0010] This invention addresses the limitations of existing optical encryption technologies based on liquid crystal planar devices, such as limited coding flexibility, low integration leading to limited information capacity, and poor encryption performance. It utilizes angular spectral diffraction theory and gradient descent algorithms to jointly optimize near-field and far-field target patterns, and combines this with traditional polarization scalarization and position multiplexing to further improve information storage capacity. Furthermore, it leverages the non-commutativity of the Jones matrix to achieve three different far-field holographic images based on the stacking order of three stacked liquid crystal devices. To enable those skilled in the art to better understand this invention, specific embodiments are described below. It should be noted that these descriptions are not intended to limit the scope of protection of this invention. Any obvious changes or modifications made by those skilled in the art without departing from the principles of this invention should be considered to fall within the scope of protection defined by the claims of this invention. All creations based on the concept of this invention are protected by this invention.

[0011] As an optical holographic technology, this optical encryption method based on cross-correlation liquid crystal planar devices includes the following steps: S1. Construct a joint optimization model for near-field and far-field target patterns. Based on angular spectral diffraction theory, establish a light propagation model in the liquid crystal device to describe the propagation laws of near-field and far-field images, and clarify the mapping relationship between near-field and far-field images and the control parameters of the liquid crystal device. Introduce the gradient descent algorithm, taking the near-field and far-field target patterns as the optimization objective, and iteratively optimize the phase parameters of the liquid crystal device. Set the number of iterations to 100 and the learning rate to 0.02, until the number of iterations is greater than 100, thus completing the construction of the optimization model.

[0012] S2. Simulation and testing of cross-correlation liquid crystal devices. The optimized model constructed in step S1 is applied to three liquid crystal devices respectively. Figure 1 The simulation results of near-field and far-field images of cross-correlation liquid crystal devices are presented. Through simulation tests, three liquid crystal devices successfully generated one far-field image and one near-field image respectively in the case of a single layer. When the three liquid crystal devices were stacked in pairs, ensuring that the centers of the two devices were aligned during stacking, an image was successfully generated for each pair of stacked devices.

[0013] S3. Building upon S1, position multiplexing and polarization multiplexing mechanisms are introduced to increase the number of images generated when two liquid crystals are stacked. Position multiplexing sets three different position parameters d1, d2, and d3, corresponding to three different imaging distances of the liquid crystal devices. Polarization multiplexing employs two illumination methods: left-handed circularly polarized light illumination and right-handed circularly polarized light illumination. The optimized algorithm is then applied to the three liquid crystal devices. Figure 2 Simulation results of cross-correlation liquid crystal devices combined with traditional multiplexing methods are presented. When working individually, each device can still generate a far-field image and a near-field image. When the two liquid crystal devices are stacked, the three stacked combinations are simulated under three position parameters (d1, d2, d3) and two polarization illumination methods. Each stacked device can generate an independent image at each position and under each polarization illumination. Finally, each stacked device can generate 6 images.

[0014] S4. Building upon S3, a Jones matrix is ​​introduced to utilize its non-commutativity for encryption of the order control when three liquid crystal devices are stacked. Jones matrices J1, J2, and J3 are constructed for each of the three liquid crystal devices. The matrix elements are determined based on the phase modulation characteristics of the liquid crystal devices, where J1 corresponds to the light modulation characteristics of liquid crystal device 1, J2 to liquid crystal device 2, and J3 to liquid crystal device 3. J1, J2, and J3 satisfy non-commutativity. The Jones matrix is ​​integrated into the optimization algorithm of S3, combining position multiplexing, polarization multiplexing mechanisms, angular spectrum diffraction theory, and gradient descent algorithm. The optimization objectives are image differences under different stacking orders and image stability in multiple scenarios. When each of the three liquid crystal devices works independently, it still generates one far-field image and one near-field image. For three pairs of double-stacked devices, each pair can still generate six images. By stacking the three liquid crystal devices and setting three different stacking orders, simulation tests are conducted under position parameter d1 and left-handed circularly polarized light illumination. The three different stacking orders generate three different holographic images, achieving the goal of generating different encrypted images by controlling the stacking order, further improving the security and flexibility of the encryption system.

[0015] It should be noted that any modifications and improvements can be made to the above embodiments without departing from the scope defined by the claims of this invention. Therefore, the claimed technical solutions should not be limited to any particular embodiment.

Claims

1. An optical encryption method based on a cross-correlation liquid crystal planar device, characterized in that, Includes the following steps: S1. Based on angular spectrum diffraction theory and gradient descent algorithm, a joint optimization model for near-field and far-field target patterns is constructed to collaboratively optimize the generation parameters of near-field and far-field images. S2. Select three random phases as the initial phases of the three liquid crystal planar devices. Based on the optimization model constructed in step S1, perform simulation verification to realize that when a single liquid crystal device is working, the three liquid crystal devices independently generate a far-field image and a near-field image, and when two liquid crystal devices are stacked, any two liquid crystal devices can generate an image after being stacked. S3. A reuse mechanism is introduced into the optimization algorithm in step S1. The reuse mechanism includes position reuse and polarization reuse. Secondary optimization is performed by combining angular spectrum diffraction theory and gradient descent algorithm. Simulation verification shows that when a single liquid crystal device is working, the three liquid crystal devices still independently generate a far-field image and a near-field image respectively. When two liquid crystal devices are stacked, any two liquid crystal devices can generate six images after being stacked. S4. In the optimization algorithm of step S3, a Jones matrix is ​​introduced. Utilizing the non-commutativity of the Jones matrix, and combining position multiplexing and polarization multiplexing mechanisms, three optimizations are performed. Simulation verification shows that: when a single liquid crystal device is working, the three liquid crystal devices independently generate a far-field image and a near-field image; when two liquid crystal devices are stacked, any two stacked liquid crystal devices can generate six images; when three liquid crystal devices are stacked, three different holographic images can be generated according to the different stacking order of the three liquid crystal devices.

2. The optical encryption method based on a cross-correlation liquid crystal planar device according to claim 1, characterized in that, In step S1, the angular spectral diffraction theory is used to describe the propagation law of light and provides theoretical support for the generation of far-field images; the gradient descent algorithm is used to iteratively optimize the image generation parameters and minimize the deviation between near-field and far-field images and the target pattern.

3. The optical encryption method based on a cross-correlation liquid crystal planar device according to claim 1, characterized in that, In step S3, the position multiplexing is achieved by setting three different position parameters (d1, d2, d3), and the polarization multiplexing is achieved by two illumination methods: left-handed circularly polarized light and right-handed circularly polarized light.

4. The optical encryption method based on a cross-correlation liquid crystal planar device according to claim 1, characterized in that, In step S4, corresponding Jones matrices J1, J2, and J3 are constructed for the three liquid crystal devices respectively. The elements of the Jones matrices are determined according to the phase modulation characteristics of the liquid crystal devices, and J1, J2, and J3 satisfy non-commutativity.

5. The optical encryption method based on a cross-correlation liquid crystal planar device according to claim 1, characterized in that, In step S1, the gradient descent algorithm is set to iterate 100 times and the learning rate is set to 0.

02. The optimization model is completed when the number of iterations is greater than 100.

6. The optical encryption method based on a cross-correlation liquid crystal planar device according to claim 1, characterized in that, In step S2, when stacking dual liquid crystal devices, ensure that the centers of the two devices are aligned.

7. The optical encryption method based on a cross-correlation liquid crystal planar device according to claim 1, characterized in that, In step S4, when the three liquid crystal devices are stacked, a simulation test is performed under the conditions of position parameter d1 and left-hand circularly polarized light illumination. Three different holographic images are generated for the three different stacking orders.

8. An optical encryption method based on a cross-correlation liquid crystal planar device according to any one of claims 1-7, characterized in that, The liquid crystal planar device features high controllability, high integration, and low power consumption, and is used to modulate the phase, amplitude, and polarization parameters of incident light.

9. An optical encryption method based on a cross-correlation liquid crystal planar device according to any one of claims 1-7, characterized in that, The technology can be widely used in information storage, secure communication, and identity authentication.

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