Optical encryption device, optical decryption device, and optical encryption communication system

Abstract

The present application relates to an optical encryption device, an optical decryption device and an optical encryption communication system, the encryption device comprising: a control unit for generating a control signal based on a pre-encryption protocol; an optical control unit for encoding the plaintext optical signal based on the control signal to obtain the ciphertext optical signal; wherein the encryption protocol is based on the correspondence between the refractive index distribution of the optical control element and the control signal; the optical control element comprises an electrically controllable adjustable scattering medium, the electrically controllable adjustable scattering medium comprises a plurality of tunable anisotropic micro elements, and the refractive index distribution of the electrically controllable adjustable scattering medium can be changed based on the control signal loaded thereon. The system of the present application has good response speed and response accuracy, so as to improve the communication efficiency and communication quality of the communication system under the premise of ensuring the communication security.

Description

Technical Field

[0001] This invention relates to the field of encrypted communication technology, and in particular to an optical encryption device, an optical decryption device, and an optical encrypted communication system. Background Technology

[0002] Optical encryption is a typical and efficient communication encryption method. Its essence is to scramble and encode the inherent information of a plaintext image through optical transformation processes such as interference, diffraction, and scattering, thereby achieving good encryption results. Scattering is a common phenomenon in light propagation. Thanks to the anisotropy and randomness of the tiny units within the scattering medium, when a light signal carrying plaintext information enters the scattering medium, the light signal propagates randomly within the medium, forming a speckle pattern, thus achieving random encoding of the plaintext information. However, within the memory effect range of the scattering medium, the autocorrelation function of a static scattering medium is approximately equal to the autocorrelation function of its speckle pattern. This makes single-channel random encryption techniques based on static scattering media vulnerable to phase recovery full-ciphertext attacks, reducing communication security.

[0003] To address the aforementioned issues, existing optical encryption methods based on scattering media typically employ mechanical methods, such as using a motor to drive the scattering medium to change its angle with the incident light, allowing the scattering effect of the medium to reversibly switch between multiple states. This enables multi-level control of the optical signal, achieving dynamic random encoding. However, this method heavily relies on the stability of the mechanical system to ensure reversible switching between different scattering states, thus requiring expensive, precision mechanical systems to achieve acceptable errors within the optical range. Furthermore, due to the limitations of the mechanical structure, this method has a slow response speed, and after a period of use, wear and tear on the mechanical structure leads to a decrease in response accuracy. Additionally, the mechanical structure often occupies a significant amount of space, hindering system integration and miniaturization, which contradicts the current trend towards miniaturization and portability in optical systems. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides an optical encryption device, an optical decryption device, and an optical encryption communication system, which solves the technical problems of slow response speed and poor response accuracy when using scattering media for optical encryption in the prior art.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0008] In a first aspect, embodiments of the present invention provide an optical encryption device for encoding plaintext optical signals to generate ciphertext optical signals, the encryption device comprising:

[0009] Control unit, used to generate control signals based on a pre-prepared encryption protocol;

[0010] An optical control unit is used to encode the plaintext optical signal based on the control signal to obtain the ciphertext optical signal;

[0011] The encryption protocol is a protocol based on the correspondence between the refractive index distribution of the optical control element and the control signal; the optical control element includes an electrically controlled tunable scattering medium, which includes multiple tunable anisotropic micro-elements that can change their refractive index distribution based on the control signal applied to them.

[0012] Optionally, the optical control unit includes: the optical control element, or an encryption module configured based on the inverse function of the refractive index distribution of the optical control element; wherein the refractive index distribution of the optical control element is described by a light field modulation function;

[0013] When the optical control unit includes the optical control element, the optical control element changes its refractive index distribution based on the control signal to encode the plaintext light signal transmitted through the optical control element to obtain the ciphertext light signal.

[0014] When the optical control unit includes the encryption module, the encryption module multiplies the inverse function of the corresponding optical field modulation function with the plaintext optical signal based on the control signal to obtain the ciphertext optical signal.

[0015] Optionally, the anisotropic micro-element in the electrically controlled tunable scattering medium is: a tiny scattering unit containing anisotropic electro-optic materials.

[0016] Optionally, the optical control element further includes a first substrate and a second substrate disposed opposite to each other, and the electrically controlled tunable scattering medium is disposed between the first substrate and the second substrate; the first substrate includes a first light-transmitting layer and a first conductive layer, the first conductive layer being disposed between the first light-transmitting layer and the electrically controlled tunable scattering medium; the second substrate includes a second light-transmitting layer and a second conductive layer, the second conductive layer being disposed between the second light-transmitting layer and the electrically controlled tunable scattering medium.

[0017] Optionally, the control signal is an electrical signal, and the optical field modulation function of the optical control element includes any one of the following: point spread function, speckle image, and optical transfer matrix.

[0018] Optionally, before generating the control signal, the control unit is further configured to obtain the correspondence between the optical field modulation function of the optical control element and the electrical signal based on a measurement process, wherein the measurement process includes:

[0019] The control unit applies the electrical signal contained in the encryption protocol to the optical control element, and measures the optical field modulation function of the optical control element under the currently applied electrical signal; and,

[0020] Repeat the above measurement process until the optical field modulation function corresponding to all electrical signals contained in the encryption protocol is obtained.

[0021] Optionally, the optical field modulation function of the optical control element is an optical transfer matrix, and the measurement of the optical field modulation function of the optical control element under the currently applied electrical signal includes:

[0022] S10. The control unit generates an N-order Hadamard orthogonal basis matrix;

[0023] S20. The control unit extracts the i-th column from the Hadamard orthogonal basis matrix as the basis vector for the i-th measurement. Where i is a positive integer not greater than N;

[0024] S30. The control unit converts the basis vectors into a square matrix form and superimposes the basis vectors in the square matrix form. The phase shifts form four phase shift matrices.

[0025] S40. The control unit expands the four phase shift matrices respectively to obtain four expanded matrices;

[0026] S50. The control unit sequentially loads the four expansion matrices onto the spatial light modulator to obtain four input light fields for input optical control elements.

[0027] S60. The control unit obtains the light intensity distribution in the form of a square array after the four input light fields are controlled by optical control elements through a photodetector.

[0028] S70, The control unit distributes the light intensity in the array form. The light intensity distribution is obtained by stretching the image to obtain a vector form. The basis vector of the i-th measurement is calculated according to formula (1). Corresponding output light field vector The formula (1) is

[0029]

[0030] S80. Repeat S20 to S70 until all basis vectors in the Hadamardian orthogonal matrix have been traversed. The output light field vector corresponding to the basis vector is obtained.

[0031] S90, Based on the basis vectors and the output light field vector The optical transmission matrix K of the optical control element is calculated according to formula (2). V Formula (2) is:

[0032]

[0033] In formula (2), express The generalized inverse matrix.

[0034] Secondly, embodiments of the present invention provide an optical decryption device for decoding ciphertext optical signals to generate plaintext optical signals, comprising:

[0035] A processing unit for generating decryption signals based on a pre-defined decryption protocol;

[0036] An optical decryption unit is used to decode the ciphertext optical signal based on the decryption signal to obtain the plaintext optical signal;

[0037] The decryption protocol is a decryption strategy set according to the encryption protocol of the corresponding encryption device. The decryption strategy is set based on the correspondence between the refractive index distribution of the optical control element and the control signal. The optical control element includes an electrically controlled tunable scattering medium, which includes multiple tunable anisotropic micro-elements that can change their refractive index distribution based on the control signal applied to them.

[0038] Optionally, the optical control unit includes: the optical control element, or a decryption module set based on the inverse function of the refractive index distribution of the optical control element; wherein the refractive index distribution of the optical control element is described by a light field modulation function;

[0039] When the optical decryption unit includes the optical control element, the optical control element changes its refractive index distribution based on the decryption signal to decode the ciphertext light signal transmitted through the optical control element and obtain the plaintext light signal.

[0040] When the optical control unit includes the decryption module, the decryption module multiplies the inverse function of the corresponding optical field modulation function with the ciphertext optical signal based on the decryption signal to obtain the plaintext optical signal.

[0041] Thirdly, embodiments of the present invention also provide an optical encrypted communication system, including a transmitter and a receiver.

[0042] The transmitting end includes the encryption device described in the first aspect. The encryption device encodes the plaintext optical signal generated by the transmitting end based on the encryption protocol to obtain a ciphertext optical signal for transmission on the transmission channel.

[0043] The receiving end includes the decryption device described in the second aspect, which decodes the ciphertext optical signal received from the transmission channel based on the decryption protocol to obtain the plaintext optical signal;

[0044] Wherein, when the optical control unit of the encryption device includes the optical control element, the optical control decryption unit of the decryption device includes: the decryption module set based on the inverse function of the light field modulation function of the optical control element;

[0045] When the optical decryption unit of the decryption device includes the optical control element, the optical control unit of the encryption device includes the encryption module configured based on the inverse function of the light field modulation function of the optical control element.

[0046] (III) Beneficial Effects

[0047] The encryption device, decryption device, and encrypted communication system proposed in this invention achieve multi-level control of optical signals around an optical control element. The electrically controlled tunable scattering medium layer in the optical control element can change its refractive index distribution based on a control signal applied to it. That is, the optical control element can quickly switch between multiple scattering effects according to different control signals, achieving multi-level control of the optical signal. Because the electrically controlled tunable scattering medium can quickly change its refractive index distribution according to the change of the control signal, it has a faster response speed compared to the mechanical structure in the prior art, thereby achieving multi-level control of the optical signal, broadening the dimension of the encryption channel, and improving the security of the communication system. Moreover, since the switching of the scattering effect of the optical control element is achieved by the electrically controlled tunable scattering medium layer changing its refractive index distribution based on the control signal, it does not rely on a mechanical structure, thus maintaining good response accuracy even after prolonged use. Therefore, compared to existing encrypted communication methods based on mechanical structures, the communication system provided in this invention has better response speed and response accuracy, thereby improving the communication efficiency and quality of the communication system while ensuring communication security.

[0048] Furthermore, the optical control element provided in this embodiment of the invention has a simple structure and low cost. It can be configured as a small-sized element to meet the requirements of overall miniaturization of communication systems, improve the integration of communication systems, and has good application prospects. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the structure of an optical encryption device provided in the embodiment;

[0050] Figure 2 This is a schematic diagram of the structure of an optical control element provided in the embodiment;

[0051] Figure 3 This is a schematic diagram of another optical encryption device provided in the embodiment;

[0052] Figure 4 This is a schematic diagram of another optical encryption device provided in the embodiment;

[0053] Figure 5 This is a schematic diagram of the structure of a decryption device provided in the embodiment;

[0054] Figure 6 This is a schematic diagram of the optical path of a decryption device provided in the embodiment;

[0055] Figure 7 The results are from experiments conducted using an optical encrypted communication system, as shown in the examples. Detailed Implementation

[0056] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] The optical control element in the communication system proposed in this invention is essentially based on the existing technology of using scattering media to randomly encode and encrypt optical signals. It further proposes an optical control element based on an electrically controllable tunable scattering medium. By changing the electrical signal applied to the optical control element, its refractive index distribution is altered, allowing the optical control element to reversibly switch between different scattering effects. This enables multi-channel encryption of the communication system, that is, multi-level control of the optical signal. Since the electrically controllable tunable scattering medium can respond to electrical signals in real time and does not experience physical wear, it has significant advantages in response speed and accuracy compared to existing mechanical structures.

[0058] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0059] Example 1

[0060] This embodiment provides an optical encryption device for encoding plaintext optical signals to generate ciphertext optical signals. For example... Figure 1 As shown, the encryption device includes a control unit 10 and an optical control unit 20, specifically:

[0061] The control unit 10 is used to generate control signals based on a pre-defined encryption protocol. The control unit is an electronic device with data processing capabilities, specifically a computer, controller, or processor. The control signals are used to instruct the optical control unit 20 to encode the plaintext optical signal to generate a ciphertext optical signal according to the encryption protocol.

[0062] The optical control unit 20 is used to encode the plaintext optical signal based on the control signal to obtain the ciphertext optical signal.

[0063] The encryption protocol is based on the correspondence between the refractive index distribution of the optical control element and the control signal. The optical control element includes an electrically controlled tunable scattering medium, which comprises multiple tunable anisotropic micro-elements capable of changing its refractive index distribution based on the control signal applied to it. The control signal can be an electrical signal, specifically a voltage signal or a current signal. The refractive index distribution of the optical control element can be described by an optical field modulation function. Specifically, the optical field modulation function includes any one of a point spread function, a speckle pattern, and an optical transfer matrix.

[0064] In a preferred embodiment of this invention, the anisotropic micro-elements in the electrically controlled tunable scattering medium are: anisotropic micro-scattering units comprising electro-optic materials. More specifically, the electro-optic material layer includes, but is not limited to, polymer-dispersed liquid crystal, polymer-stabilized liquid crystal, doped polymer-dispersed liquid crystal, doped polymer-stabilized liquid crystal, and lithium niobate. Based on this electrically controlled tunable scattering medium, the optical control element only requires a thickness of tens of micrometers to achieve a sufficiently strong scattering effect for optical control, thus making it highly suitable for miniaturized communication devices or systems.

[0065] Preferably, the electrically controlled tunable scattering medium is a polymer-dispersed liquid crystal. A polymer-dispersed liquid crystal is a material formed by mixing liquid crystal and polymer monomers in a certain molar percentage, followed by phase separation under specific conditions, resulting in liquid crystal droplets of varying sizes (micrometer scale) dispersed within a network of polymer molecules. In this embodiment, the aforementioned liquid crystal droplets are anisotropic micro-elements. Due to the anisotropic refractive index of the liquid crystal droplets, the direction of the droplet's directional vector is controlled by an external electric field, thereby controlling the electrically controlled tunable scattering medium and achieving optical modulation. Specifically, without an external electric field, the directional vector of the liquid crystal droplets in the electrically controlled tunable scattering medium is oriented by the anchoring force of the polymer surrounding them. Due to the complex structure of the polymer network, the directional vectors of the liquid crystal droplets are all different and can be considered as random orientations. In the incident direction of the light signal, a strong scattering effect is formed due to the refractive index difference between the liquid crystal droplets and the polymer, and among the individual liquid crystal droplets. When an external electric field is applied, the director of the liquid crystal droplets in the electrically controlled tunable scattering medium deflects to varying degrees in the direction of the electric field, altering the propagation path of the light signal within the scattering medium and thus changing the scattering effect. This allows for switching between different random encoding effects of the light signal. Under the combined action of the anchoring force of the polymer on the liquid crystal droplets and the electric field force, the director of each liquid crystal droplet in the electrically controlled tunable scattering medium can rotate at any angle, enabling reversible switching between different scattering effects.

[0066] More specifically, such as Figure 2As shown, the optical control element 20 further includes a first substrate 202 and a second substrate 203 disposed opposite to each other, with the electrically controlled tunable scattering medium layer 201 disposed between the first substrate 202 and the second substrate 203; the first substrate 202 includes a first light-transmitting layer 2021 and a first conductive layer 2022, with the first conductive layer 2022 disposed between the first light-transmitting layer 2021 and the electrically controlled tunable scattering medium layer 201; the second substrate 203 includes a second light-transmitting layer 2031 and a second conductive layer 2032, with the second conductive layer 2032 disposed between the second light-transmitting layer 2031 and the electrically controlled tunable scattering medium layer 201. Without loss of generality, the first conductive layer 2022 and the second conductive layer 2032 are light-transmitting, so that the light signal can be incident on the first substrate 202 to the electrically controlled tunable scattering medium layer 201 for control, and then emitted from the side of the second substrate 203 away from the electrically controlled tunable scattering medium layer 201. The electrical signal is applied to the first conductive layer 2022 and the second conductive layer 2032. The electrically controlled tunable scattering medium layer 201 changes its refractive index distribution based on the control signal applied between the first conductive layer 2022 and the second conductive layer 2032. Preferably, the first substrate 202 and the second substrate 203 are both ITO conductive glass, and the ITO film layer of the ITO conductive glass is disposed on the side close to the electrically controlled tunable scattering medium layer 201.

[0067] This embodiment also provides a fabrication step for the above-mentioned optical control element 20, the fabrication step including:

[0068] (1) Clean the ITO conductive glass.

[0069] (2) Cutting ITO conductive glass. Cut the cleaned glass into small pieces of a preset size according to the required size. In this embodiment, the ITO conductive glass is cut into two 2cm×2cm squares.

[0070] (3) Bonding ITO conductive glass to form a box. Align two pieces of ITO conductive glass in parallel so that the ITO film layer of each piece of ITO conductive glass faces the other piece of ITO conductive glass. Mix a small ball with a diameter of 20μm and a UV-curable adhesive and apply it to the area between the two pieces of ITO conductive glass near the edge. When applying the adhesive, leave an opening for filling the box with liquid crystal mixture. Press gently to make the thickness of the box uniform and expose it to ultraviolet light to cure it.

[0071] (4) Filling the liquid crystal mixture. E7 nematic liquid crystal and polymer prepolymer NOA-65 are mixed in a molar ratio of 3:7, heated to 70°C and stirred evenly. Then, the mixture is applied to the cell opening using a pipette. Under capillary action, the liquid crystal mixture is gradually and evenly distributed in the cell.

[0072] (5) Exposure and curing of liquid crystal mixture. Under ultraviolet light, the polymer prepolymer undergoes a polymerization reaction to form a polymer network, causing phase separation between the liquid crystal and the polymer to form liquid crystal microdroplets.

[0073] The encryption device proposed in this invention achieves multi-level control of optical signals around an optical control element. The electrically controlled tunable scattering medium layer within the optical control element can change its refractive index distribution based on a control signal applied to it. That is, the optical control element can rapidly switch between multiple scattering effects according to different control signals, achieving multi-level control of the optical signal. Because the electrically controlled tunable scattering medium can rapidly change its refractive index distribution according to changes in the control signal, it has a faster response speed compared to mechanical structures in the prior art, thereby achieving multi-level control of the optical signal, broadening the dimensions of the encryption channel, and improving the security of the communication system. Moreover, since the switching of the scattering effect of the optical control element is achieved by the electrically controlled tunable scattering medium layer changing its refractive index distribution based on the control signal, without relying on mechanical structures, it can still maintain good response accuracy even after prolonged use. Therefore, compared to existing encryption communication methods based on mechanical structures, the communication system provided by this invention has better response speed and response accuracy, thereby improving the communication efficiency and quality of the communication system while ensuring communication security.

[0074] Example 2

[0075] The optical control element provided in Embodiment 1 is actually a physical key, and the physical key it provides can change according to the control signal applied to it. The inverse function of the optical field modulation function corresponding to the optical control element can serve as a soft key corresponding to the optical control element, used in conjunction with it to achieve the encryption and decryption process at both ends of the information transmission channel. Specifically, the physical key can be used in the encryption device, and the corresponding soft key in the decryption device; conversely, the soft key can be used in the encryption device, and the corresponding physical key in the decryption device.

[0076] Specifically, in the encryption device of Embodiment 1, the optical control unit includes: the optical control element, or an encryption module set based on the inverse function of the light field modulation function of the optical control element.

[0077] When the optical control unit includes the optical control element, the optical control element changes its refractive index distribution based on the control signal to encode the plaintext light signal transmitted through the optical control element to obtain the ciphertext light signal.

[0078] When the optical control unit includes the encryption module, the encryption module multiplies the inverse function of the corresponding optical field modulation function with the plaintext optical signal based on the control signal to obtain the ciphertext optical signal.

[0079] In a preferred embodiment of this invention, the optical control unit of the encryption device includes the optical control element, the control signal is an electrical signal, and the refractive index distribution of the optical control element is described by an optical transfer matrix. Specifically, as shown... Figure 3 As shown, the encryption device includes a control unit 10 and an optical control unit 20, wherein:

[0080] The control unit 10 is used to generate control signals based on a pre-defined encryption protocol. The encryption protocol is a protocol set based on the correspondence between the refractive index distribution of the optical control element and the electrical signal.

[0081] Specifically, the control unit includes a controller module 11 and an electrical signal generation module 12.

[0082] The controller module 11 is used to generate an initial control signal, which instructs the electrical signal generation module 12 to generate an electrical signal carrying control information. The electrical signal is applied to the optical control element to change the refractive index distribution of the optical control element.

[0083] The electrical signal generation module 12 is used to receive the initial control signal and generate a corresponding electrical signal based on the initial control signal. Specifically, the electrical signal may be a voltage signal, and the voltage signal may carry control information through its amplitude, frequency, or duty cycle. The electrical signal generation module 12 may specifically be a voltage output module, which generates a corresponding voltage signal according to the initial control signal generated by the controller module 11. Preferably, the voltage signal carries control information through its amplitude.

[0084] The optical control unit 20 includes an optical control element. The optical control element changes its refractive index distribution based on the change of the electrical signal, and encodes the plaintext light signal transmitted through the optical control element to obtain the ciphertext light signal.

[0085] Furthermore, in order to obtain the refractive index distribution corresponding to the optical control element in the above-mentioned encryption device, so as to provide a soft key for the corresponding decryption device, the control unit, before generating the control signal, is also used to obtain the correspondence between the refractive index distribution of the optical control element and the electrical signal based on a measurement process, the measurement process including:

[0086] The control unit loads the electrical signals contained in the encryption protocol onto the optical control element, measures the optical transmission matrix of the optical control element under the currently loaded electrical signals, and repeats the above measurement process until the optical transmission matrices corresponding to all electrical signals contained in the encryption protocol are obtained.

[0087] Specifically, in the above measurement process, the measurement obtains the optical transmission matrix corresponding to the optical control element under the currently applied electrical signal, which specifically includes the following steps:

[0088] S10. The control unit generates an N-order Hadamard orthogonal basis matrix.

[0089] S20. The control unit extracts the i-th column from the Hadamard orthogonal basis matrix as the basis vector for the i-th measurement. Where i is a positive integer not greater than N.

[0090] S30. The control unit converts the basis vectors into a square matrix form and superimposes the basis vectors in the square matrix form. The phase shifts form four phase shift matrices.

[0091] S40. The control unit expands the four phase shift matrices respectively to obtain four expanded matrices.

[0092] S50. The control unit sequentially loads the four expansion matrices onto the spatial light modulator to obtain four input light fields for input optical control elements.

[0093] S60. The control unit obtains the light intensity distribution in the form of a square array after the four input light fields are controlled by optical control elements through a photodetector.

[0094] S70, The control unit distributes the light intensity in the array form. The light intensity distribution is obtained by stretching the image to obtain a vector form. The basis vector of the i-th measurement is calculated according to formula (1). Corresponding output light field vector The formula (1) is

[0095]

[0096] S80. Repeat S20 to S70 until all basis vectors in the Hadamard orthogonal basis matrix have been traversed. The output light field vector corresponding to the basis vector is obtained.

[0097] S90, Based on the basis vectors and the output light field vector The optical transmission matrix K of the optical control element is calculated according to formula (2). V Formula (2) is:

[0098]

[0099] In formula (2), express The generalized inverse matrix.

[0100] Based on the above measurement process, the correspondence between the optical transmission matrix of the optical control element and the electrical signal can be obtained. When the encryption device and the decryption device communicate, based on the electrical signal used by the encryption device, the decryption device can use the generalized inverse matrix of the optical transmission matrix corresponding to the control signal as the corresponding soft key to decrypt the received ciphertext optical signal and obtain the plaintext optical signal.

[0101] In another preferred embodiment of this invention, the optical control unit of the encryption device includes the encryption module, and the refractive index distribution of the optical control element is described by an optical transfer matrix.

[0102] like Figure 4 As shown, the encryption device includes a control unit 10 and an optical control unit 20, specifically:

[0103] The control unit 10 is used to generate control signals based on a pre-prepared encryption protocol.

[0104] The optical control unit 20 includes an encryption module, which is used to multiply the generalized inverse matrix of the corresponding optical transmission matrix as a soft key with the plaintext optical signal based on the control signal to obtain the ciphertext optical signal.

[0105] Example 3

[0106] Corresponding to the encryption device provided in Embodiment 1 or 2, this embodiment provides an optical decryption device for decoding ciphertext optical signals to generate plaintext optical signals.

[0107] like Figure 5 As shown, the encryption device includes a processing unit 30 and an optical decryption unit 40:

[0108] The processing unit 30 is used to generate a decryption signal based on a pre-defined decryption protocol.

[0109] The optical decryption unit 40 is used to decode the ciphertext optical signal based on the decryption signal to obtain the plaintext optical signal.

[0110] The decryption protocol is a decryption strategy set according to the encryption protocol of the corresponding encryption device. The decryption strategy is set based on the correspondence between the refractive index distribution of the optical control element and the control signal. The optical control element includes an electrically controlled tunable scattering medium, which includes multiple tunable anisotropic micro-elements that can change their refractive index distribution based on the control signal applied to them.

[0111] Specifically, the optical control unit includes: the optical control element, or a decryption module set based on the inverse function of the refractive index distribution of the optical control element, wherein the refractive index distribution of the optical control element is described by a light field modulation function.

[0112] When the optical decryption unit includes the optical control element, the optical control element changes its refractive index distribution based on the decryption signal to decode the ciphertext light signal transmitted through the optical control element and obtain the plaintext light signal.

[0113] When the optical control unit includes the decryption module, the decryption module multiplies the inverse function of the corresponding optical field modulation function with the ciphertext optical signal based on the decryption signal to obtain the plaintext optical signal.

[0114] To better understand the specific application method of the above-mentioned decryption device, this embodiment takes the optical control unit including optical control elements as an example to describe the specific structure of the decryption device in detail.

[0115] like Figure 6 As shown, in a preferred embodiment of this invention, the decryption device includes: a reference light component, a reflective spatial light modulator (SLM), a first condenser lens (L1), an optical control element (PDLC), a photodetector component, and a processing unit (not shown in the original text). Figure 6 shown in ). Specifically:

[0116] The reference light assembly includes a laser, a spatial light filter system (SFS), a half-wave plate (HWP), and a first polarizer (P). The laser is a 543nm helium-neon gas laser (model: REO-33361). The laser emitted from the laser passes through the spatial light filter system (SFS), which consists of two lenses and a small aperture, to filter out clutter and expand the beam, resulting in a coherent plane wave with a thick beam and uniform intensity. The coherent plane wave is then modulated by the half-wave plate (HWP) and the polarizer (P) to obtain incident light with a polarization direction that is the same as the long axis of the reflective spatial light modulator (SLM).

[0117] The reflective spatial light modulator SLM (model: HOLOEYE NIR-011) receives encrypted data in the form of electrical signals from the transmission channel, encodes the incident light emitted by the reference light component, generates an encrypted light signal, and then focuses it onto the optical control element after passing through the first condenser lens L1 (focal length of 50mm).

[0118] The control unit generates a corresponding voltage signal based on the decryption protocol corresponding to the encrypted data and loads it onto the optical control element PDLC. The optical control element PDLC includes a polymer-dispersed liquid crystal. The director of the liquid crystal droplets in the polymer-dispersed liquid crystal is deflected to a certain extent under the electric field provided by the voltage signal, so that its refractive index distribution corresponds to the encrypted data based on the decryption protocol. This decodes the encrypted light signal incident from the reflective spatial light modulator SLM to obtain the clear light signal, which then hits the photodetector component.

[0119] The light detection component includes a second condenser lens L2, a second polarizer A, and a charge-coupled device (CCD) camera (also known as an image sensor or image controller). The second condenser lens L2 has a numerical aperture of 0.25 and a magnification of 10x, and is used to collect the plaintext light signal scattered by the optical control element. The second polarizer A, perpendicular to the long axis of the reflective spatial light modulator (SLM), acts as an analyzer to filter out ballistic light from the collected plaintext light signal before it strikes the CCD camera. After receiving the plaintext light signal, the CCD camera converts it into a plaintext electrical signal carrying target data, which is used for direct display on a screen or for computer equipment to extract the target data from the plaintext electrical signal.

[0120] Example 4

[0121] This embodiment also provides an optical encrypted communication system, including a transmitter and a receiver.

[0122] The transmitting end includes the encryption device described in Embodiment 1 or 2. The encryption device encodes the plaintext optical signal generated by the transmitting end based on the encryption protocol to obtain a ciphertext optical signal, which is used for transmission on the transmission channel.

[0123] The receiving end includes the decryption device described in Embodiment 3. The decryption device decodes the ciphertext optical signal received from the transmission channel based on the decryption protocol to obtain the plaintext optical signal.

[0124] Wherein, when the optical control unit of the encryption device includes the optical control element, the optical control decryption unit of the decryption device includes: the decryption module set based on the inverse function of the light field modulation function of the optical control element.

[0125] When the optical decryption unit of the decryption device includes the optical control element, the optical control unit of the encryption device includes the encryption module configured based on the inverse function of the light field modulation function of the optical control element.

[0126] It should be noted that the above-mentioned encryption and decryption protocols can be included in the encryption communication protocol used by the above-mentioned optical encryption communication system and integrated on a single device. When the device needs to use the encryption protocol, it obtains the corresponding encryption protocol by accessing the encryption protocol part of the encryption communication protocol. When the device needs to use the decryption protocol, it obtains the corresponding decryption protocol by accessing the decryption protocol part of the encryption communication protocol.

[0127] Corresponding to the above-described encrypted communication system, the optical control unit of the encryption device includes the encryption module, and the optical decryption unit of the decryption device includes the optical control element. This embodiment also provides a communication method, which includes:

[0128] S1. Obtain the correspondence between the refractive index distribution of the optical control element and the electrical signal. Specifically, in this embodiment, the refractive index distribution is set as the optical transmission matrix of the optical control element.

[0129] S1 includes the following sub-steps:

[0130] S101. The receiving end loads the electrical signal contained in the decryption protocol onto the optical control element. Specifically, in this embodiment, a voltage signal is applied between the first conductive layer and the second conductive layer of the optical control element, and the refractive index distribution, i.e., the scattering state, of the optical control element is changed by adjusting the amplitude of the voltage signal. As an exemplary illustration of the decryption protocol, this embodiment sets the amplitudes of the voltage signal contained in the decryption protocol to 0Vpp, 10Vpp, and 16Vpp, respectively.

[0131] S102. Measure the optical transmission matrix of the optical control element under the currently applied electrical signal.

[0132] S103. Repeat steps S101 to S102 until the optical transmission matrix K corresponding to all electrical signals contained in the encryption protocol is obtained. 0vpp K 10vpp K 16vpp .

[0133] S2. Calculate the optical transmission matrix K. 0vpp K 10vpp K 16vpp The generalized inverse matrix is ​​used as the soft key. Specifically, the optical transmission matrix K corresponding to the three voltage signals in S103 is... 0vpp K 10vpp K16vpp The generalized inverse matrices are respectively expressed as

[0134] S3. Based on the above-mentioned encrypted communication protocol and the above-mentioned encrypted communication system, encrypted communication is carried out to transmit target data.

[0135] S3 specifically includes the following sub-steps:

[0136] S301. The transmitting end modulates the target data to be transmitted to obtain plaintext data, which is represented as follows:

[0137] S302. The sending end selects a corresponding soft key based on the encryption protocol and the encryption channel to be used by the target data. The soft key is... One of them, used uniformly in this step. This indicates that it is based on a soft key. According to formula (3), the plaintext light signal Encryption is performed to obtain ciphertext data. The encrypted data is transmitted over the transmission channel.

[0138] Formula (3) is as follows:

[0139]

[0140] S303. The receiving end receives the ciphertext data and demodulates the ciphertext data based on a reflective spatial light modulator to obtain a ciphertext optical signal.

[0141] S304. The decryption device at the receiving end loads a voltage signal of corresponding amplitude between the first and second conductive layers of the optical control element according to the decryption protocol, so that the optical control element controls the ciphertext optical signal according to the decryption protocol to obtain the plaintext optical signal.

[0142] S305. The optical detection component receives the plaintext optical signal and converts the plaintext optical signal into a plaintext electrical signal carrying the target data, which is used to display it directly on the display screen or to have a computer device extract the target data from the plaintext electrical signal.

[0143] Based on the specific steps described above, this embodiment also conducted experimental verification, and the experimental results are as follows: Figure 7As shown, Figure (a) is the plaintext pattern contained in the encrypted data transmitted through the encrypted channels corresponding to 0Vpp, 10Vpp, and 16Vpp; Figure (c) is the encrypted data received by the receiving end in step S303; Figure (b) is the plaintext pattern obtained by decrypting the encrypted data obtained from the encrypted channels corresponding to 0Vpp, 10Vpp, and 16Vpp in step S304; and Figure (d) is the pattern obtained by decryption when the voltage signal does not correspond to the encryption protocol. It can be seen that when the receiving end does not know the encrypted communication protocol, it can only obtain disordered noise, which proves that the encrypted communication system provided by the present invention can prevent eavesdropping and thus ensure the information security of the communication system.

[0144] The encrypted communication method proposed in this invention, based on the tunable optical control element, increases the encryption dimension of the communication system, expands the information capacity of the encrypted communication system, and makes the information transmitted by the communication system more secure.

[0145] Since the systems / devices described in the above embodiments of the present invention are systems / devices used to implement the methods of the above embodiments of the present invention, those skilled in the art can understand the specific structure and modifications of the systems / devices based on the methods described in the above embodiments of the present invention, and therefore will not be repeated here. All systems / devices used in the methods of the above embodiments of the present invention fall within the scope of protection of the present invention.

[0146] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0147] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions.

[0148] It should be noted that any reference numerals placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In claims that enumerate several means, several of these means may be embodied by the same hardware. The use of the terms first, second, third, etc., is merely for convenience of expression and does not indicate any order. These terms can be understood as part of the component names.

[0149] Furthermore, it should be noted that in the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0150] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims should be interpreted to include both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0151] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, then this invention should also include these modifications and variations.

Claims

1. An optical encryption device, characterized in that, The encryption device is used to encode plaintext optical signals to generate ciphertext optical signals, and includes: Control unit, used to generate control signals based on a pre-prepared encryption protocol; An optical control unit is used to encode the plaintext optical signal based on the control signal to obtain the ciphertext optical signal; The encryption protocol is based on the correspondence between the refractive index distribution of the optical control element and the control signal. The optical control element includes an electrically controlled tunable scattering medium, which comprises multiple tunable anisotropic micro-elements capable of changing their refractive index distribution based on the control signal applied to them. The optical control unit includes the optical control element, or an encryption module based on the inverse function of the refractive index distribution of the optical control element. The refractive index distribution of the optical control element is described by a light field modulation function. The electrically controlled tunable scattering medium includes a polymer-dispersed liquid crystal, which is a material formed by mixing liquid crystal with polymer monomers, followed by phase separation, and dispersing liquid crystal droplets of varying sizes within a network of polymer molecules; the liquid crystal droplets are the tunable anisotropic micro-elements. Without an external electric field, the director of the liquid crystal droplets in the electrically controlled tunable scattering medium is randomly oriented. In the incident direction of the light signal, a scattering effect is formed due to the refractive index difference between the liquid crystal droplets and the polymer, and between each liquid crystal droplet. When an external electric field is applied, the director of the liquid crystal droplets in the electrically controlled tunable scattering medium deflects to different degrees in the direction of the electric field as the electric field strength changes, thereby changing the propagation path of the light signal inside the scattering medium and thus changing the scattering effect, realizing the switching of the random encoding effect of the light signal.

2. The encryption device according to claim 1, characterized in that, When the optical control unit includes the optical control element, the optical control element changes its refractive index distribution based on the control signal to encode the plaintext light signal transmitted through the optical control element to obtain the ciphertext light signal. When the optical control unit includes the encryption module, the encryption module multiplies the inverse function of the corresponding optical field modulation function with the plaintext optical signal based on the control signal to obtain the ciphertext optical signal.

3. The encryption device according to claim 2, characterized in that, The anisotropic micro-element in the electrically controlled tunable scattering medium is: a tiny scattering unit containing the anisotropy of electro-optic materials.

4. The encryption device according to claim 2, characterized in that, The optical control element further includes a first substrate and a second substrate disposed opposite to each other, and the electrically controlled tunable scattering medium is disposed between the first substrate and the second substrate; the first substrate includes a first light-transmitting layer and a first conductive layer, the first conductive layer being disposed between the first light-transmitting layer and the electrically controlled tunable scattering medium; the second substrate includes a second light-transmitting layer and a second conductive layer, the second conductive layer being disposed between the second light-transmitting layer and the electrically controlled tunable scattering medium.

5. The encryption device according to claim 2, characterized in that, The control signal is an electrical signal, and the optical field modulation function of the optical control element includes any one of the following: point spread function, speckle image, and optical transfer matrix.

6. The encryption device according to claim 5, characterized in that, Before generating the control signal, the control unit is also used to obtain the correspondence between the optical field modulation function of the optical control element and the electrical signal based on a measurement process, the measurement process including: The control unit applies the electrical signal contained in the encryption protocol to the optical control element, and measures the optical field modulation function of the optical control element under the currently applied electrical signal; and, Repeat the above measurement process until the optical field modulation function corresponding to all electrical signals contained in the encryption protocol is obtained.

7. The encryption device according to claim 6, characterized in that, The optical field modulation function of the optical control element is an optical transfer matrix. The measurement of the optical field modulation function of the optical control element under the currently applied electrical signal includes: S10. The control unit generates an N-order Hadamard orthogonal basis matrix; S20. The control unit extracts the i-th column from the Hadamard orthogonal basis matrix as the basis vector for the i-th measurement. Where i is a positive integer not greater than N; S30. The control unit converts the basis vectors into a square matrix form and superimposes the basis vectors in the square matrix form. The phase shifts form four phase shift matrices. , , , ; S40. The control unit expands the four phase shift matrices respectively to obtain four expanded matrices; S50. The control unit sequentially loads the four expansion matrices onto the spatial light modulator to obtain four input light fields for input optical control elements. S60. The control unit obtains the light intensity distribution in the form of a square array after the four input light fields are controlled by optical control elements through a photodetector. ; S70, The control unit distributes the light intensity in the array form. The light intensity distribution is obtained by stretching the image to obtain a vector form. The basis vector of the i-th measurement is calculated according to formula (1). Corresponding output light field vector The formula (1) is: （1）； S80. Repeat S20~S70 until all basis vectors in the Hadamard orthogonal basis matrix have been traversed. The output light field vector corresponding to the basis vector is obtained. ; S90, Based on the basis vectors and the output light field vector The optical transmission matrix of the optical control element is calculated according to formula (2). Formula (2) is: （2）； In formula (2), express The generalized inverse matrix.

8. An optical decryption device, characterized in that, Used to decode ciphertext optical signals and generate plaintext optical signals, including: A processing unit for generating decryption signals based on a pre-defined decryption protocol; An optical decryption unit is used to decode the ciphertext optical signal based on the decryption signal to obtain the plaintext optical signal; The decryption protocol is a decryption strategy set according to the encryption protocol of the corresponding encryption device. The decryption strategy is set based on the correspondence between the refractive index distribution of the optical control element and the control signal. The optical control element includes an electrically controlled tunable scattering medium, which includes multiple tunable anisotropic micro-elements that can change their refractive index distribution based on the control signal applied to them. The optical decryption unit includes the optical control element, or a decryption module set based on the inverse function of the refractive index distribution of the optical control element. The refractive index distribution of the optical control element is described by a light field modulation function. The electrically controlled tunable scattering medium is a polymer-dispersed liquid crystal, which is a material formed by mixing liquid crystal with polymer monomers, followed by phase separation, and dispersing liquid crystal droplets of varying sizes within a network of polymer molecules; the liquid crystal droplets are the tunable anisotropic micro-elements. Without an external electric field, the director of the liquid crystal droplets in the electrically controlled tunable scattering medium is randomly oriented. In the incident direction of the light signal, a scattering effect is formed due to the refractive index difference between the liquid crystal droplets and the polymer, and between each liquid crystal droplet. When an external electric field is applied, the director of the liquid crystal droplets in the electrically controlled tunable scattering medium deflects to different degrees in the direction of the electric field as the electric field strength changes, thereby changing the propagation path of the light signal inside the scattering medium and thus changing the scattering effect, realizing the switching of the random encoding effect of the light signal.

9. The decryption device according to claim 8, characterized in that, When the optical decryption unit includes the optical control element, the optical control element changes its refractive index distribution based on the decryption signal to decode the ciphertext light signal transmitted through the optical control element and obtain the plaintext light signal. When the optical decryption unit includes the decryption module, the decryption module multiplies the inverse function of the corresponding optical field modulation function with the ciphertext optical signal based on the decryption signal to obtain the plaintext optical signal.

10. An optical encryption communication system, comprising a transmitter and a receiver, characterized in that, The transmitting end includes the encryption device according to any one of claims 1 to 7, wherein the encryption device encodes the plaintext optical signal generated by the transmitting end based on the encryption protocol to obtain a ciphertext optical signal for transmission on the transmission channel; The receiving end includes the decryption device as described in claim 8 or 9, which decodes the ciphertext optical signal received from the transmission channel based on the decryption protocol to obtain the plaintext optical signal; Wherein, when the optical control unit of the encryption device includes the optical control element, the optical decryption unit of the decryption device includes: the decryption module set based on the inverse function of the light field modulation function of the optical control element; When the optical decryption unit of the decryption device includes the optical control element, the optical control unit of the encryption device includes the encryption module configured based on the inverse function of the light field modulation function of the optical control element.

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