Photoelectric detector with multichannel encryption function and application thereof

Abstract

The invention belongs to the technical field of optical communication data encryption transmission, and particularly relates to a photoelectric detector with a multi-channel encryption function and application thereof. According to the method, array structure photoelectric detector units based on bias voltage selective configuration are adopted, and for different incident light signals, bias voltages of all the photoelectric detector units in a silent state are calibrated to serve as secret keys for encryption; the method breaks through the channel number limitation of a dual-channel technology, has flexible expansion capability (the channel number n is greater than or equal to 3), and can be successfully applied to high-security transmission of static image and dynamic image streams. The physical encryption strategy not only improves the image security, but also has very strong universality and expandability. And by increasing the channel number n and the array scale m, the encryption level is further improved, and the information transmission security is ensured. The method is of great significance to development of a large-scale data communication technology and can be used for encryption and authentication of large-scale image data.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical communication data encryption transmission, and particularly relates to a photodetector with multi-channel encryption function and its application. Background Art

[0002] With the advent of the big data era, the explosive growth of information volume has posed unprecedented challenges to the data throughput and reliability of communication systems. Optical communication systems, with their significant advantages in long-distance, high-speed, and large-capacity data transmission, have become an ideal choice to meet the needs of modern communication. However, in an open optical wireless communication environment, data transmission faces serious eavesdropping risks. Attackers may steal signals through diffusion effects, scattering, or by setting diffraction mirrors using non-line-of-sight channels, and even steal information by capturing scattered light. Therefore, information encryption is particularly important.

[0003] Quantum key distribution (QKD), as an encryption protocol based on the principles of quantum mechanics, can theoretically provide absolute security, but its data transmission rate and working distance are limited. Traditional encryption modules are mainly based on software algorithms and are gradually threatened by advanced computer systems or artificial intelligence. Therefore, researchers have tried to design encryption modules from the hardware side, and physical encryption of photodetectors as optical information receivers has received much attention. In recent years, with the discovery of the bipolar response mechanism and the development of electrically tunable dual-band detectors, channel switching and decoding of dual-band photodetectors have been achieved through bias voltages, thus improving the encryption level. However, this technology is limited to two fixed channels and still faces significant scalability challenges in large-scale communication and high-throughput data transmission.

[0004] Patent No. CN111093011A discloses an optical sensor with encryption function and an image data encryption method. The optical sensor includes: a pixel array; a random number generation; and an image sensing chip, coupled to the pixel array and the random number generator, for obtaining image data via the pixel array and sensing ambient light via the pixel array, so that the random number generator generates corresponding random number data, wherein the image sensing chip encrypts the image data according to the random number data to output encrypted image data. However, the information detection and processing of the optical sensor involved in this invention are still separated, and the encryption method adopted is based on software algorithms.

[0005] The patent with the publication number CN117527985A discloses a neuromorphic vision sensor with an encryption function and an in-situ physical image encryption method. The neuromorphic vision sensor includes: a sensing and computing integrated module, which is used to sense the external visual image, and then use the optical signal to perform pre-processing on the sensed image, including encryption, decryption, destruction, and denoising of the image, to obtain the pre-processed image; a memory and computing integrated module, which is used to receive the pre-processed image, perform post-processing on the pre-processed image, including encoding, recognition, and classification of the image, and store the weight factors for image post-processing. This invention adopts a neuromorphic vision sensor with integrated sensing and computing, and realizes the physical encryption of images in-situ within the sensor. However, the encryption logic of this invention is limited to the dual-channel optical signal transmission mode. When facing some high-dimensional and high-complexity image encryption requirements, its encryption level is relatively low, and the data volume of signal transmission is restricted. Summary of the Invention

[0006] Aiming at the above problems or deficiencies, to solve the problem that traditional optical communication encryption technologies are usually limited to single-channel or dual-channel signal processing and are difficult to meet the requirements of large-scale and high-throughput data transmission, the present invention provides a photodetector with a multi-channel encryption function and its application.

[0007] To achieve the above-mentioned invention purpose, the specific technical solutions of the present invention are as follows:

[0008] A photodetector with a multi-channel encryption function, including: a photodetector array, a bias voltage selective configuration module, and an information encryption processing module.

[0009] The photodetector array is composed of m photodetector units, and the m photodetector units respond to light sources of n wavelengths, where n≥3, and the response refers to the change in current of the photodetector unit after illumination.

[0010] The bias voltage selective configuration module dynamically adjusts the critical bias voltage according to the wavelength of the incident light source. The critical bias voltage refers to the bias voltage applied to the photodetector unit that makes the photocurrent zero, and then the photodetector unit enters the silent state; using the critical bias voltage as the encryption key, which dynamically adjusts with the change of the incident wavelength, to achieve the pre-calibration of the critical bias voltage under the synchronous incidence of multiple light beams.

[0011] As the key to realize the encryption function, the bias selective configuration module dynamically adjusts the critical bias voltage according to the wavelength of the incident light source, and uses this critical bias voltage as the encryption key. When the wavelength of the incident light source changes, the bias selective configuration module will adjust the bias voltage applied to the photodetector unit accordingly, so that the photocurrent is zero, and then the photodetector unit enters a silent state. The critical bias voltage is dynamically adjusted as the incident wavelength changes, providing a high degree of flexibility and security for the encryption process. In this way, pre-calibration under synchronous multi-beam incidence can be achieved to ensure that the signal of each channel can be accurately encrypted and decrypted.

[0012] The information encryption processing module independently encodes the bias information corresponding to the n incident light source wavelengths and each photodetector unit in the photodetector array (pixel device) to generate a chaotic encrypted image. During the multi-channel encryption process, the signal of each channel carries specific information, which is encrypted through independent bias coding. This encoding method makes the encrypted image appear chaotic, greatly improving the concealment and security of the encrypted signal. The encryption level can be further improved by continuously iterating by increasing the number of channels n and the array size m, meeting the high throughput requirements of large-scale data communications and realizing highly secure multi-channel image encryption transmission.

[0013] Furthermore, the photodetector array uses a photodetector unit of alloy thin film silicon-based heterojunction to form an array as encryption hardware. The sensitivity of the silicon-based heterojunction photodetector array to a light source of a specific wavelength can be used to selectively receive and process signals of different wavelengths. This feature enables the photodetector array to adapt to the needs of multi-channel signal transmission and provides a hardware foundation for implementing complex encryption strategies.

[0014] Furthermore, the alloy film is selected from Se 0.25 Te 0.75 Alloy thin film material. Se 0.25 Te 0.75 The absorption spectrum of the film covers a wide spectral range from visible light to short-wave infrared, with an absorption peak near 980nm. This wide spectrum absorption property enables the photodetector array to respond to light sources of multiple wavelengths, providing hardware support for multi-channel encryption. By optimizing the composition ratio and preparation process of the film, the absorption characteristics can be further adjusted to meet different application requirements.

[0015] Furthermore, the bias voltage of each photodetector unit is controlled separately by a digital-to-analog converter DAC, and a bias point voltage is provided by a DAC method, which is located outside the pixel; a preset digital signal is transmitted to a data selector of each photodetector unit through a shift register, and the corresponding voltage regulator output voltage is latched, thereby realizing independent bias configuration of each photodetector unit.

[0016] Furthermore, the encryption method of the photodetector with multi-channel encryption function is applied to communication data encryption:

[0017] The bias voltage selective configuration module sets a dynamic adjustment mechanism according to the application scenario and security requirements: determines the number of incident light source channels (number of wavelengths) n and the number of photodetector units m; dynamically adjusts the critical bias voltage of each photodetector unit according to the wavelength of the incident light source; uses the critical bias voltage as the encryption key, which dynamically adjusts with the change of the incident wavelength, to achieve pre-calibration of the critical bias voltage under the synchronous incidence of multiple beams.

[0018] After calibrating the independent bias voltage configuration of each photodetector unit in the silent state, and using this bias voltage as the key for data encryption to control the response of optical signals of different wavelengths; if the incident light wavelength matches the bias voltage value V s matches, the detector output signal is 1; if not, the output signal is 0.

[0019] The information encryption processing module independently encodes the bias voltage information corresponding to the n incident light source wavelengths and each photodetector unit in the photodetector array to generate a chaotic encryption image; different incident light information is independently encoded according to the bias voltage key during the encryption process to ensure that the signals of each channel can be accurately encrypted and decrypted.

[0020] Furthermore, the method of independent encoding by the information encryption processing module is that the number of permutations and combinations of the bias voltage key is 2 n -1.

[0021] Furthermore, the number of incident light source channels n is increased to iteratively improve the encryption level to meet the high throughput requirements of large-scale data communication.

[0022] Furthermore, the number of photodetector units m is increased to expand the array scale to iteratively improve the encryption level to meet the high throughput requirements of large-scale data communication.

[0023] Furthermore, both the number of incident light source channels n and the number of photodetector units m are increased to continuously iteratively improve the encryption level from two dimensions of n and m to iteratively improve the encryption level to meet the high throughput requirements of large-scale data communication.

[0024] Furthermore, the communication data encryption is multi-channel image encryption.

[0025] 1). The multi-channel encrypted photodetector array proposed by the present invention has successfully broken through the channel number limit of traditional dual-channel encryption technology. The multi-channel encryption strategy significantly enhances the encryption intensity. Moreover, by increasing the number of channels n and the array scale m, the encryption level can be continuously iteratively improved, further reducing the correlation between the encrypted image and the original image, making the encrypted image more difficult to be cracked and stolen. Through the bias selectivity configuration module, the number of channels n can be flexibly expanded according to actual needs, greatly improving the scalability and adaptability of the system. This flexible expansion ability enables the technology to process signals in multiple bands simultaneously, meet the high throughput requirements of large-scale data communication, and be applicable to various complex application scenarios.

[0026] 2). The encryption technology of the present invention is physical encryption based on hardware, and the encryption function is realized through a photodetector array and a bias selectivity configuration module. The bias selectivity configuration module can dynamically adjust the critical bias voltage according to the wavelength of the incident light source, and use this critical bias voltage as the encryption key. This dynamic adjustment mechanism makes the encryption key change with the change of the incident wavelength, greatly improving the flexibility and security of encryption. This dynamic adjustment mechanism can also flexibly set and adjust the encryption strategy according to different application scenarios and security requirements, improving the overall security of the system. Compared with traditional software encryption methods, hardware-level encryption has higher security and reliability, can effectively resist machine learning attacks and advanced computer system threats. At the same time, hardware-level encryption can significantly reduce the burden on software and improve the operation efficiency of the system.

[0027] In summary, the present invention adopts an array-structured photodetector unit based on bias selectivity configuration. For different incident optical signals, by calibrating the bias voltage of each photodetector unit in the silent state (i.e., the "0" state) as the key for encryption, this encryption strategy breaks through the channel number limit of dual-channel technology, has flexible expansion ability (the number of channels n≥3), and can be successfully applied to the high-security transmission of static images and dynamic image streams. This physical encryption strategy not only improves the image security, but also has strong versatility and scalability. By increasing the number of channels n and the array scale m, the encryption level can be further improved to ensure the security of information transmission. It is of great significance to the development of large-scale data communication technology and can be used for large-scale image data encryption and authentication. The present invention uses a photodetector array as the encryption hardware to implement an on-chip integrated multi-channel pixel-level encryption chip, thus realizing a multi-channel optical signal transmission, encryption, and reception integration technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the vertical heterojunction photodetector structure composed of n-type silicon and p-type Se 0.25 Te 0.75 thin film for an embodiment.

[0029] Figure 2 It is the photocurrent I-t curve of the photodetector in the embodiment under the irradiation of 980nm laser at different bias voltages.

[0030] Figure 3 It is the I-t curve diagram of the photodetector in the embodiment under the incidence of a light source in the 1310nm communication band.

[0031] Figure 4 It is the encryption logic diagram of single-beam, double-beam, and triple-beam signal transmission of the photodetector in the embodiment.

[0032] Figure 5 It is the preset key information diagram of n-channel signal transmission of the photodetector in the embodiment.

[0033] Figure 6 It is the image multi-channel encryption transmission and algorithm verification diagram of the photodetector in the embodiment.

[0034] Figure 7 It is the average entropy and correlation coefficient diagram of the three-channel communication image of the photodetector in the embodiment. Detailed implementation manners

[0035] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0036] A photodetector with a multi-channel encryption function provided in this embodiment, as Figure 1 shown, its 3D device structure shows a vertical heterojunction detector structure composed of n-type silicon and p-type Se 0.25 Te 0.75 thin films.

[0037] In this embodiment, the alloy thin film selects Se 0.25 Te 0.75 alloy thin film material. The absorption spectrum of the Se 0.25 Te 0.75 thin film covers a wide spectral range from visible light to short-wave infrared, and the absorption peak is located near 980nm. This wide spectral absorption characteristic enables the photodetector array to respond to light sources of multiple wavelengths, providing hardware support for multi-channel encryption. By optimizing the composition ratio and preparation process of the thin film, the absorption characteristics can be further adjusted to meet different application requirements.

[0038] In this embodiment, magnetron sputtering is used to prepare a high-quality and uniform Se 0.25 Te 0.75 thin film; post-annealing treatment of the sputtered thin film can improve the crystallinity of the thin film and reduce the defect density. This method prepares an alloy thin film with good crystallization state and uniformity, providing a basis for a high-performance photodetector array.

[0039] In this embodiment, Se with a thickness of 135 nm 0.25 Te 0.75 thin film is used as the p-type material, and lightly doped n-Si is used as the n-type material to construct a vertical heterostructure. By optimizing the energy band structure of the heterojunction, the energy band bending occurs at the Se 0.25 Te 0.75 / n-Si interface to form a built-in electric field; this built-in electric field can effectively separate the photo-generated electron-hole pairs and transport them to the two electrodes, thereby forming a photocurrent. This optimized energy band structure not only improves the response speed of the photodetector but also enhances its electrical transport and light response capabilities. The lithography process is used for 32×32 array patterning preparation to ensure the uniform size and shape of each photodetector unit, thereby improving the performance consistency and stability of the detector unit and providing reliable hardware support for high-security multi-channel image encryption.

[0040] In this embodiment, three near-infrared communication bands of 980 nm, 1064 nm, and 1310 nm are selected to design multi-channel image pixel-level keys. Such a setting is because these three bands are key near-infrared communication bands, which is conducive to collecting rich useful information, achieving multi-band imaging effects, and realizing key links such as quantum key distribution in quantum communication.

[0041] Figure 2 This is the bias-dependent photocurrent polarity switching mechanism of the photodetector provided in this embodiment. After the 980 nm wavelength light source is incident, the I-t curve of the photocurrent under different external biases shows that the photocurrent polarity reverses with the increase of V ds . When the bias V ds reaches the critical value of 107 mV (this critical value is defined as V s ), the photocurrent is zero, and the device enters the silent mode.

[0042] Figure 3 This is the response speed of the photodetector prepared in this embodiment when the 1310 nm communication band light source is incident, showing the normalized photocurrent time-domain curve measured at a 1 Hz light switch frequency. At the 1310 nm band, the device response speed reaches 72 - 97 us, indicating that the extraction efficiency of photo-generated carriers is very high.

[0043] The photodetector with multi-channel encryption function prepared based on the embodiment is used for multi-channel image encryption: Figure 4The optical signal transmission encryption logic of this embodiment shows the encryption logics for single-beam, double-beam, and triple-beam optical signal transmissions. Different incident optical information will be encoded correspondingly according to the bias key during the encryption process. In the silent state ("0" state), the bias value of the calibration device is defined as the key to control the responses of optical signals with different wavelengths. If the wavelength of the incident light matches the bias value V s , the detector output signal is "1"; if not, the output signal is "0".

[0044] Figure 5 For the preset key information of n-channel signal transmission, the number of permutations and combinations of the bias key is 2 n -1. This encoding method significantly increases the encryption difficulty as the number of channels increases, enhancing the confidentiality of information. Se 0.25 Te 0.75 The thin-film silicon-based heterojunction photodetector array is used as the hardware platform to perform independent bias encoding on each photodetector unit pixel, further improving the security of the encryption strategy.

[0045] Specifically, the bias value of each pixel is associated and set with the light source information through specific rules (the matching rule between the incident light wavelength and the bias value V s ). This enables the encryption of the information of each pixel during the transmission process, greatly improving the concealment of the image information.

[0046] In the embodiment, the bias of each pixel (photodetector unit) is controlled separately by a digital-to-analog converter DAC. The DAC located outside the pixel provides the bias point voltage; the preset digital signal is transmitted to the data selector of each pixel through a shift register, and the output voltage of the corresponding voltage regulator is latched, thereby realizing the independent bias configuration of each pixel. And each pixel in the array is encrypted separately, greatly improving the concealment of the image information.

[0047] Figure 6 This is the flowchart of the multi-channel encrypted transmission of images and its algorithm verification provided in this embodiment. The sending end transmits an image containing the information "UEOE" and encrypts the image using the above multi-channel pixel-level encryption strategy. By randomly setting the bias values of 32×32 unit devices, the imaging information of the corresponding three-band light is generated. The receiving end can successfully decrypt the original image only when it has the same light source and bias encoding; the receiver without the key cannot recover the correct information from the transmitted image.

[0048] To evaluate the image encryption effect, this embodiment uses two key technical indicators, the average entropy and the correlation coefficient, for analysis. Figure 7Comparison of entropy increase and correlation coefficient between three-channel and two-channel image encryption in this embodiment. The average entropy is used to measure the randomness or uncertainty of an image. The higher the average entropy, the more uniform the distribution of image pixels and the more difficult it is to predict. The higher the entropy increase (the entropy difference between the encrypted image and the original image), the greater the randomness of the image and the higher the security. Another measure, the correlation coefficient, the closer it is to 0, indicates that the correlation (correlation coefficient) between the original image and the encrypted image is smaller. Calculate the key performance indicators of the two-channel encryption and multi-channel pixel-level encryption strategies respectively. The entropy increase between the encrypted image and the original image of the multi-channel pixel-level encryption strategy exceeds 1.3, and the correlation coefficient is as low as 0.069, significantly better than the two-channel encryption strategy (entropy increase is 0.35, average correlation coefficient is 0.6). The experimental results show that the multi-channel encryption scheme can not only improve the randomness of the encrypted image, but also effectively reduce the correlation with the original image, thus improving the encryption security.

[0049] As can be seen from the above embodiments, the present invention calibrates the bias voltage of the photodetector unit in the silent state (i.e., the "0" state) as the key for encryption. This encryption strategy breaks through the channel number limit of the two-channel technology and has flexible expansion capabilities (n≥3), and can be successfully applied to the high-security transmission of static images and dynamic image streams. This encryption strategy not only improves the image security, but also has strong versatility and scalability. By increasing the number of channels n and the array scale m, the encryption level can be further improved to ensure the security of information transmission.

Claims

1. A photoelectric detector with multi-channel encryption function, characterized in that: It includes a photodetector array, a bias voltage selective configuration module and an information encryption processing module; The photodetector array is composed of m photodetector units, and the m photodetector units respond to light sources of n wavelengths, where n≥3, and the response refers to the amount of current change of the photodetector unit after light exposure; The bias selective configuration module dynamically adjusts the critical bias voltage according to the wavelength of the incident light source. The critical bias voltage refers to the bias voltage applied to the photodetector unit to make the photocurrent zero, so that the photodetector unit enters a silent state; the critical bias voltage is used as an encryption key, which is dynamically adjusted as the incident wavelength changes, so as to realize the pre-calibration of the critical bias voltage under the simultaneous incidence of multiple light beams; The information encryption processing module independently encodes the bias information corresponding to the n incident light source wavelengths and each photodetector unit in the photodetector array to generate a chaotic encrypted image.

2. The photoelectric detector with multi-channel encryption function as claimed in claim 1, characterized in that: The photoelectric detector array uses alloy thin film silicon-based heterojunction photoelectric detector units to form an array as encryption hardware.

3. The photoelectric detector with multi-channel encryption function as claimed in claim 1, characterized in that: The alloy film is selected from Se 0.25 Te 0.75 Alloy film material.

4. The photoelectric detector with multi-channel encryption function as claimed in claim 1, characterized in that: The bias voltage of each photodetector unit is controlled separately by a digital-to-analog converter DAC, and a bias point voltage is provided by a DAC method, which is located outside the pixel; a preset digital signal is transmitted to a data selector of each photodetector unit through a shift register, and the corresponding voltage regulator output voltage is latched, thereby realizing independent bias configuration of each photodetector unit.

5. An encryption method for a photoelectric detector with a multi-channel encryption function, characterized in that: Applied to communication data encryption; The bias selective configuration module sets a dynamic adjustment mechanism according to the application scenario and security requirements: determine the number of incident light source wavelength channels n and the number of photodetector units m; dynamically adjust the critical bias of each photodetector unit according to the wavelength of the incident light source; use the critical bias as the encryption key, which is dynamically adjusted as the incident wavelength changes, to achieve pre-calibration of the critical bias under multi-beam synchronous incidence; After calibrating the independent bias configuration of each photodetector unit in the silent state, the bias voltage is used as the key for data encryption to control the response of optical signals of different wavelengths. If the incident light wavelength is different from the bias voltage value V s If the match is found, the detector output signal is 1; if the match is not found, the output signal is 0; The information encryption processing module independently encodes the bias information corresponding to n types of incident light source wavelengths and each photodetector unit in the photodetector array to generate a chaotic encrypted image; different incident light information is independently encoded according to the bias key during the encryption process to ensure that the signal of each channel can be accurately encrypted and decrypted.

6. The encryption method of the photoelectric detector with multi-channel encryption function as claimed in claim 5, characterized in that: The information encryption processing module is independently encoded in such a way that the number of permutations and combinations of the bias key is 2 n -1, n is the number of channels.

7. The encryption method of the photoelectric detector with multi-channel encryption function as claimed in claim 5, characterized in that: The number n of wavelength channels of the incident light source increases to continuously iterate and improve the encryption level.

8. The encryption method of the photoelectric detector with multi-channel encryption function as claimed in claim 5, characterized in that: The number m of the photoelectric detector units increases, and the array scale is expanded to continuously iterate and improve the encryption level to meet the high throughput requirements of large-scale data communications.

9. The encryption method of the photoelectric detector with multi-channel encryption function as claimed in claim 5, characterized in that: The number n of wavelength channels of the incident light source and the number m of photoelectric detector units are both increased, and the encryption level is continuously and iteratively improved from two dimensions of n and m.

10. The encryption method of the photoelectric detector with multi-channel encryption function as claimed in claim 5, characterized in that: The communication data encryption is multi-channel image encryption.

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