Optoelectronic detector with multi-channel encryption function and application thereof

Abstract

The application belongs to the technical field of optical communication data encryption transmission, and particularly relates to an optoelectronic detector with a multi-channel encryption function and application thereof. The application adopts an array structure optoelectronic detector unit based on selective configuration of bias voltage, and aims at different incident light signals. The bias voltage of each optoelectronic detector unit in a silent state is calibrated as a key for encryption. The application breaks through the channel number limitation of double-channel technology, has flexible expansion capability (channel number n >= 3), and can be successfully applied to high-security transmission of static images and dynamic image streams. The physical encryption strategy not only improves the image security, but also has strong universality and scalability. The encryption level can be further improved by increasing the channel number n and the array size m, so as to ensure the security of information transmission. The application has important significance for the development of large-scale data communication technology, and can be used for large-scale image data encryption and authentication.

Description

Technical Field

[0001] This invention belongs to the field of optical communication data encryption transmission technology, specifically relating to a photodetector with multi-channel encryption function and its application. Background Technology

[0002] With the advent of the big data era, the explosive growth of information 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 modern communication needs. However, in open optical wireless communication environments, data transmission faces serious eavesdropping risks. Attackers may steal signals through diffusion effects, scattering, or by using diffractometers in non-line-of-sight channels, or even by capturing scattered light to steal information. Therefore, information encryption is particularly important.

[0003] Quantum key distribution (QKD), as an encryption protocol based on quantum mechanics, theoretically offers absolute security, but its data transmission rate and operating distance are limited. Traditional encryption modules, primarily based on software algorithms, are increasingly threatened by advanced computer systems or artificial intelligence. Therefore, researchers are attempting to design encryption modules from the hardware level, with physical encryption of photodetectors as optical information receivers receiving significant 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 voltage, thereby 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 CN111093011A discloses an optical sensor with encryption function and an image data encryption method. The optical sensor includes: a pixel array; a random number generator; and an image sensing chip coupled to the pixel array and the random number generator. The chip is used to acquire image data via the pixel array and to sense ambient light via the pixel array, causing the random number generator to generate random number data accordingly. The image sensing chip encrypts the image data based on 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 used is based on a software algorithm.

[0005] Patent CN117527985A discloses a neuromorphic vision sensor with encryption function and an in-situ physical encryption method for images. The neuromorphic vision sensor includes: a sensing and computing integrated module for sensing external visual images, and then using optical signals to perform preprocessing on the sensed images, including encryption, decryption, destruction, and denoising, to obtain a preprocessed image; and a storage and computing integrated module for receiving the preprocessed image, performing postprocessing on the preprocessed image, including image encoding, recognition, and classification, and storing weighting factors for image postprocessing. This invention uses a sensing, storage, and computing integrated neuromorphic vision sensor to achieve in-situ physical encryption of images within the sensor. However, the encryption logic of this invention is limited to a dual-channel optical signal transmission method. When facing some high-dimensional and highly complex image encryption requirements, its encryption level is low, and the amount of data transmitted by the signal is limited. Summary of the Invention

[0006] To address the aforementioned problems or shortcomings, and to resolve the issue that traditional optical communication encryption technologies are typically limited to single-channel or dual-channel signal processing and cannot meet the demands of large-scale, high-throughput data transmission, this invention provides a photodetector with multi-channel encryption capabilities and its applications.

[0007] To achieve the above-mentioned objectives, the specific technical solution of this invention is as follows:

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

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

[0010] The bias selective configuration module dynamically adjusts the critical bias voltage according to the wavelength of the incident light source. The critical bias voltage is the bias voltage applied to the photodetector unit that makes the photocurrent zero, thereby putting the photodetector unit into a silent state. The critical bias voltage is used as the encryption key and is dynamically adjusted with the change of the incident wavelength to achieve pre-calibration of the critical bias voltage under multi-beam synchronous incident conditions.

[0011] The bias selective configuration module, crucial for encryption, dynamically adjusts the critical bias voltage based on the wavelength of the incident light source, using this critical bias voltage as the encryption key. When the wavelength of the incident light source changes, the bias selective configuration module adjusts the bias voltage applied to the photodetector unit accordingly, reducing the photocurrent to zero and thus silencing the photodetector unit. This dynamic adjustment of the critical bias voltage with changing incident wavelength provides high flexibility and security for the encryption process. In this way, pre-calibration under multi-beam synchronous incidence can be achieved, ensuring accurate encryption and decryption of signals from each channel.

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

[0013] Furthermore, the photodetector array employs photodetector units of alloy thin-film silicon-based heterojunction as the encryption hardware. Utilizing the sensitivity of the silicon-based heterojunction photodetector array to specific wavelength light sources, selective reception and processing of signals of different wavelengths can be achieved. This characteristic enables the photodetector array to adapt to the needs of multi-channel signal transmission, providing a hardware foundation for implementing complex encryption strategies.

[0014] Furthermore, the alloy thin film is made of Se. 0.25 Te 0.75 Alloy thin film materials. 0.25 Te 0.75 The thin film exhibits an absorption spectrum covering a broad spectral range from visible light to short-wave infrared, with an absorption peak around 980 nm. This broad-spectral absorption characteristic enables the photodetector array to respond to light sources of various wavelengths, providing hardware support for multi-channel encryption. By optimizing the composition ratio and fabrication process of the thin 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). The bias point voltage is provided by the DAC and is located outside the pixel. A preset digital signal is transmitted to the data selector of each photodetector unit through a shift register, and the corresponding voltage regulator output voltage is latched, thereby realizing the independent bias voltage configuration of each photodetector unit.

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

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

[0018] After calibrating the independent bias voltage configuration of each photodetector unit in the silent state, this bias voltage is used as a key for data encryption to control the response of light signals at different wavelengths; if the incident light wavelength and the bias voltage value V s If there is a match, the detector outputs a signal of 1; if there is no match, the output signal is 0.

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

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

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

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

[0023] Furthermore, the number of incident light source channels n and the number of photodetector units m are both increased, and the encryption level is continuously improved iteratively from the two dimensions of n and m 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 in this invention successfully overcomes the channel number limitation of traditional dual-channel encryption technology. The multi-channel encryption strategy significantly enhances encryption strength and can continuously iterate and improve the encryption level by increasing the number of channels (n) and the array size (m), further reducing the correlation between the encrypted image and the original image, making the encrypted image more difficult to crack and steal. Through the bias selective configuration module, the number of channels (n) can be flexibly expanded according to actual needs, greatly improving the system's scalability and adaptability. This flexible expansion capability allows the technology to process signals in multiple bands simultaneously, meeting the high throughput requirements of large-scale data communication and making it suitable for various complex application scenarios.

[0026] 2) The encryption technology of this invention is based on hardware-based physical encryption, which achieves encryption functionality through a photodetector array and a bias selective configuration module. The bias selective configuration module can dynamically adjust the critical bias voltage according to the wavelength of the incident light source, using this critical bias voltage as the encryption key. This dynamic adjustment mechanism allows the encryption key to change with the incident wavelength, greatly improving the flexibility and security of encryption. This dynamic adjustment mechanism can also flexibly set and adjust encryption strategies 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, effectively resisting machine learning attacks and advanced computer system threats. At the same time, hardware-level encryption can significantly reduce the software burden and improve system operating efficiency.

[0027] In summary, this invention employs an array-structured photodetector unit based on bias-selective configuration. For different incident light signals, the bias voltage of each photodetector unit in its silent state (i.e., "0" state) is calibrated and used as the key for encryption. This encryption strategy overcomes the channel number limitation of dual-channel technology, possessing flexible scalability (channel number n≥3), and can be successfully applied to high-security transmission of static images and dynamic image streams. This physical encryption strategy not only improves image security but also has strong versatility and scalability. Furthermore, the encryption level can be further improved by increasing the number of channels n and the array size m, ensuring the security of information transmission. This 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. This invention uses a photodetector array as encryption hardware to realize an on-chip integrated multi-channel pixel-level encryption chip, thereby achieving an integrated technology for multi-channel optical signal transmission, encryption, and reception. Attached Figure Description

[0028] Figure 1 Examples of n-type silicon and p-type Se 0.25 Te 0.75 A schematic diagram of a vertical heterojunction photodetector structure made of thin film.

[0029] Figure 2 The photocurrent It curves of the photodetector under different bias voltages under 980nm laser irradiation are shown in the example.

[0030] Figure 3 The image shows the It curve of the photodetector under the incident light source of the 1310nm communication band in the example embodiment.

[0031] Figure 4 The following is an example of the encryption logic diagram for single-beam, dual-beam, and triple-beam signal transmission of a photodetector.

[0032] Figure 5 This is a diagram showing the preset key information for the n-channel signal transmission of a photodetector in an embodiment.

[0033] Figure 6 This diagram illustrates the multi-channel encrypted transmission of images and algorithm verification of a photodetector used in an embodiment.

[0034] Figure 7 The diagram shows the average entropy and correlation coefficient of the three-channel communication image of the photodetector in the example. Detailed Implementation

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

[0036] This embodiment provides a photodetector with multi-channel encryption function, such as... Figure 1 As shown, its 3D device structure demonstrates n-type silicon and p-type Se. 0.25 Te 0.75 A vertical heterojunction detector structure made of thin film.

[0037] In this embodiment, the alloy thin film is selected from Se. 0.25 Te 0.75 Alloy thin film materials, Se 0.25 Te 0.75 The thin film exhibits an absorption spectrum covering a broad spectral range from visible light to short-wave infrared, with an absorption peak around 980 nm. This broad-spectral absorption characteristic enables the photodetector array to respond to light sources of various wavelengths, providing hardware support for multi-channel encryption. By optimizing the composition ratio and fabrication process of the thin film, the absorption characteristics can be further adjusted to meet different application requirements.

[0038] This embodiment uses magnetron sputtering to prepare high-quality and highly uniform Se. 0.25 Te 0.75 Thin films; post-annealing sputtering can improve the crystallinity of the thin film and reduce the defect density. This method prepares alloy thin films with good crystallinity and uniformity, providing a basis for high-performance photodetector arrays.

[0039] This embodiment uses Se with a thickness of 135nm. 0.25 Te 0.75 The thin film, as a p-type material, is lightly doped with n-Si to become an n-type material, constructing a vertical heterostructure. By optimizing the band structure of the heterojunction, Se... 0.25 Te 0.75 The bandgap at the / n-Si interface creates a built-in electric field. This field effectively separates photogenerated electron-hole pairs and transports them to the two electrodes, generating a photocurrent. This optimized bandgap structure not only improves the response speed of the photodetector but also enhances its electrical transport and photoresponse capabilities. A 32×32 array pattern is fabricated using photolithography to ensure uniform size and shape for each photodetector unit, thereby improving the performance consistency and stability of the detector units and providing reliable hardware support for highly secure multi-channel image encryption.

[0040] This embodiment selects three near-infrared communication bands—980nm, 1064nm, and 1310nm—to design a multi-channel image pixel-level key. This arrangement is because these three bands are key near-infrared communication bands, which are beneficial for collecting rich and useful information, achieving multi-band imaging effects, and enabling key steps such as quantum key distribution in quantum communication.

[0041] Figure 2 This embodiment provides a bias-dependent photocurrent polarity switching mechanism for the photodetector. After a 980nm wavelength light source is incident, the photocurrent It curves after applying different external bias voltages show that the photocurrent polarity changes with V. ds The bias increases and then reverses. When the bias voltage V... ds The critical value of 107 mV is reached (this critical value is defined as V). s When the photocurrent is zero, the device enters silent mode.

[0042] Figure 3 The response speed of the photodetector fabricated in this embodiment under incident light at a 1310 nm communication band is shown in the normalized photocurrent time-domain curve measured at a 1 Hz optical switching frequency. At the 1310 nm band, the device response speed reaches 72–97 μs, indicating a very high extraction efficiency of photogenerated carriers.

[0043] The photodetector with multi-channel encryption function prepared based on the embodiments is used for multi-channel image encryption: Figure 4This embodiment demonstrates the encryption logic for optical signal transmission under single-beam, dual-beam, and triple-beam conditions. Different incident light information is encoded according to the bias key during encryption. In the silent state ("0" state), the bias value of the calibration device is defined as the key, used to control the response of optical signals at different wavelengths. If the incident light wavelength and the bias value V... s If there is a match, the detector outputs a signal of "1"; if there is no match, the output signal is "0".

[0044] Figure 5 Preset key information is transmitted for n-channel signals, and the number of permutations and combinations of the bias key is 2^n. n -1. This encoding method significantly increases encryption difficulty with the number of channels, enhancing information confidentiality. 0.25 Te 0.75 Using a thin-film silicon-based heterojunction photodetector array as a hardware platform, each photodetector unit pixel is independently bias-encoded, further improving the security of the encryption strategy.

[0045] Specifically, the bias value of each pixel is determined according to a specific rule (the incident light wavelength and the bias value V). s The matching rules are associated with the light source information. This ensures that the information of each pixel is encrypted during transmission, greatly improving the concealment of image information.

[0046] In this embodiment, the bias voltage of each pixel (photodetector unit) is controlled separately by a digital-to-analog converter (DAC). The bias voltage is provided by a DAC located outside the pixel. A 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 independent bias voltage configuration for each pixel. Furthermore, each pixel in the array is individually encrypted, which greatly improves the concealment of image information.

[0047] Figure 6 This is a flowchart illustrating the multi-channel encrypted transmission of images and its algorithm verification provided in this embodiment. The sending end transmits an image containing "UEOE" information and encrypts the image using the aforementioned multi-channel pixel-level encryption strategy. By randomly setting the bias voltage values ​​of 32×32 unit devices, corresponding three-band light imaging information is generated. The receiving end can only successfully decrypt the original image if it has the same light source and bias voltage encoding; receivers 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, average entropy and correlation coefficient, for analysis. Figure 7This example compares the entropy increase and correlation coefficient of three-channel and two-channel image encryption in this embodiment. Average entropy measures the randomness or uncertainty of an image; a higher average entropy indicates a more uniform distribution of image pixels, making it more unpredictable. A higher entropy increase (the entropy difference between the encrypted and original images) indicates greater randomness and higher security. Another metric, the closer the correlation coefficient is to 0, the lower the correlation between the original and encrypted images. Key performance indicators for the two-channel and multi-channel pixel-level encryption strategies were calculated. The multi-channel pixel-level encryption strategy showed an entropy increase exceeding 1.3 and a correlation coefficient as low as 0.069, significantly outperforming the two-channel encryption strategy (entropy increase of 0.35 and average correlation coefficient of 0.6). These experimental results demonstrate that the multi-channel encryption scheme not only improves the randomness of the encrypted image but also effectively reduces its correlation with the original image, thereby enhancing encryption security.

[0049] As can be seen from the above embodiments, this invention uses the bias voltage of the photodetector unit in a silent state (i.e., the "0" state) as the key for encryption. This encryption strategy overcomes the channel number limitation of dual-channel technology, possesses flexible scalability (n≥3), and can be successfully applied to high-security transmission of static images and dynamic image streams. This encryption strategy not only improves image security but also has strong versatility and scalability. By increasing the number of channels n and the array size m, the encryption level can be further improved, ensuring the security of information transmission.

Claims

1. A photodetector with multi-channel encryption function, characterized in that: It includes a photodetector array, a bias selective configuration module, and an information encryption processing module; The photodetector array consists of m photodetector units, which respond to n wavelengths of light, where n ≥ 3. The response refers to the change in current of the photodetector unit after illumination. The photodetector array uses alloy thin-film silicon-based heterojunction photodetector units as encryption hardware. The alloy thin film is selected from Se... 0.25 Te 0.75 Alloy film materials; The bias selective configuration module dynamically adjusts the critical bias voltage according to the wavelength of the incident light source. The critical bias voltage is the bias voltage applied to the photodetector unit that makes the photocurrent zero, thereby putting the photodetector unit into a silent state. The critical bias voltage is used as the encryption key and is dynamically adjusted with the change of the incident wavelength to achieve pre-calibration of the critical bias voltage under multi-beam synchronous incident conditions. The information encryption processing module independently encodes the bias information corresponding to each photodetector unit in the photodetector array for the n incident light source wavelengths to generate a chaotic encrypted image.

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

3. An encryption method for a photodetector with multi-channel encryption function, characterized in that: Used for encryption of communication data; The bias selective configuration module sets a dynamic adjustment mechanism according to the application scenario and security requirements: it determines the number of wavelength channels n of the incident light source and the number of photodetector units m; it dynamically adjusts the critical bias of each photodetector unit according to the wavelength of the incident light source; and it uses the critical bias as the encryption key, which is dynamically adjusted with the change of the incident wavelength to realize the pre-calibration of the critical bias under multi-beam synchronous incidence. After calibrating the independent bias voltage configuration of each photodetector unit in the silent state, this bias voltage is used as a key for data encryption to control the response of light signals at different wavelengths; if the incident light wavelength and the bias voltage value V s If there is a match, the detector outputs a signal of 1; if there is no match, the output signal is 0. The information encryption processing module independently encodes the bias voltage information corresponding to each photodetector unit in the photodetector array for n incident light wavelengths, generating a chaotic encrypted image; different incident light information is independently encoded according to the bias voltage key during the encryption process to ensure that the signal of each channel can be accurately encrypted and decrypted. The photodetector array uses photodetector units of alloy thin-film silicon-based heterojunction as the encryption hardware, and the alloy thin film is selected from Se. 0.25 Te 0.75 Alloy film material.

4. The encryption method for a photodetector with multi-channel encryption function as described in claim 3, characterized in that: The information encryption processing module uses an independent encoding method where the number of permutations and combinations of the bias key is 2. n -1, where n is the number of channels.

5. The encryption method for a photodetector with multi-channel encryption function as described in claim 3, characterized in that: The number of incident light source wavelength channels, n, is increased to continuously iterate and improve the encryption level.

6. The encryption method for a photodetector with multi-channel encryption function as described in claim 3, characterized in that: The number m of the photodetector units is increased to expand the array size, so as to continuously iterate and improve the encryption level and meet the high throughput requirements of large-scale data communication.

7. The encryption method for a photodetector with multi-channel encryption function as described in claim 3, characterized in that: The number of incident light source wavelength channels n and the number of photodetector units m are both increased, and the encryption level is continuously improved iteratively from the two dimensions of n and m.

8. The encryption method for a photodetector with multi-channel encryption function as described in claim 3, characterized in that: The communication data encryption is a multi-channel image encryption.

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