A white light communication mu LED device with a physical layer time domain encryption function and an encryption method and system thereof

Abstract

This invention discloses a white-light communication μLED device with physical-layer temporal encryption, along with its encryption method and system. The device is based on an InGaN / GaN blue μLED array, with orange-red μLED encryption units based on organic long-afterglow materials integrated on adjacent mesa via a masking process. These encryption units generate controllably decaying afterglow emission after the pulsed current stops. By adjusting the pulse parameters, the duration and brightness of the afterglow can be changed, thereby writing encrypted information in the temporal dimension. The blue unit outputs a high-speed communication signal, while the orange-red unit emits afterglow carrying the ciphertext. The two lights mix in space to form a stable white light output. This structure simultaneously achieves illumination, high-speed communication, and physical-layer encryption in a single device. This invention offers a highly concealed encryption mechanism, a large modulation bandwidth, a simple device structure, and compatibility with existing systems, providing crucial hardware support for high-security visible light communication.

Description

Technical Field

[0001] This invention belongs to the fields of visible light communication and semiconductor optoelectronic devices, and particularly relates to a physical layer encrypted white μLED device based on long-persistence time-domain modulation, its encryption method, and communication system. Background Technology

[0002] With the increasing demands for information security, gallium nitride (GaN)-based micro light-emitting diodes (μLEDs) are considered ideal light sources for highly reliable visible light communication (VLC) systems due to their advantages such as low resistance, capacitance delay, high modulation bandwidth, and high brightness. Since GaN-based μLEDs were first applied to visible light communication in 2010, white-light VLC systems that combine illumination and high-speed wireless transmission have received widespread attention.

[0003] However, current white-light VLC still faces key technological bottlenecks. Traditional white LEDs typically use blue LEDs to excite yellow phosphors (such as YAG:Ce3+) to obtain white light, but this method is limited by the phosphor's long photoluminescence lifetime and low modulation bandwidth (typically less than 20 MHz), making it difficult to meet the demands of high-speed communication. Although researchers have attempted to improve bandwidth using methods such as quantum dot color conversion or multi-color LED combination, these methods still rely on upper-layer software encryption algorithms (such as AES, RSA, etc.) for information security. In this case, the physical layer optical signal remains in plaintext, and attackers can recover information by probing photoelectric nodes or directly intercepting the optical signal, leaving the physical layer security of the communication link virtually unprotected.

[0004] To enhance the physical layer security of communication systems, researchers have begun exploring encryption methods that leverage the inherent physical properties of optical signals. Organic long-afterglow materials, in particular, have attracted significant attention due to their unique luminescence dynamics. These materials continue to emit light even after optical or electrical excitation ceases, with durations ranging from microseconds to milliseconds. Their afterglow decay process can be controlled through molecular structure design and excitation parameters, resulting in programmable time-response characteristics. This property makes it possible to embed encrypted information within the temporal dimension of optical signals.

[0005] While the combination of inorganic semiconductors and organic materials has been used to improve luminous efficiency or achieve full-color displays, there is currently no solution that deeply integrates the high-speed modulation characteristics of III-nitride μLEDs with the time response capabilities of organic long-persistence materials. There is still a lack of a technical solution that can simultaneously generate high-speed communication carrier light and time-domain encrypted afterglow light through a fully electroluminescent heterojunction in a monolithic structure, and seamlessly fuse the two into a composite white light output.

[0006] Therefore, existing white light communication devices cannot achieve the integrated fusion of communication carrier and encryption signal at the physical layer source. How to utilize the unique time response characteristics of organic long-afterglow materials to directly realize information steganography in μLED devices and integrate them monolithically with inorganic nitride light-emitting units to construct a composite white light source that can provide both illumination and communication while possessing physical layer encryption capabilities is a key problem that urgently needs to be solved. Summary of the Invention

[0007] Purpose of the invention: The technical problem to be solved by the present invention is to provide a white light communication μLED device and its preparation method with physical layer time domain encryption function to address the shortcomings of the prior art, so as to solve the problem that the existing visible light communication system relies too much on software encryption and lacks physical layer security protection.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A white-light communication μLED device with physical layer time-domain encryption includes:

[0010] Patterned sapphire substrate;

[0011] A III-nitride semiconductor epitaxial layer grown on the substrate, the epitaxial layer comprising, from bottom to top, a GaN buffer layer, an N-GaN layer, and an In layer. x Ga 1-x N / GaN multiple quantum well active layer and P-GaN layer;

[0012] An electrically isolated mesa array structure is etched onto the epitaxial layer, the mesa array penetrating the P-GaN layer and In. x Ga 1-x N / GaN multiple quantum well active layer and extended to N-GaN layer;

[0013] A P-type electrode is disposed on the P-GaN layer, and an N-type electrode is disposed on the N-GaN layer;

[0014] Each pair of adjacent surfaces constitutes an encrypted pixel unit, and the encrypted pixel unit includes:

[0015] (1) Blue light communication subunit: consisting of the In x Ga 1-x The structure consists of a III-nitride epitaxial layer of N / GaN multi-quantum-well structure, used to emit blue light signals as the main channel for high-speed communication.

[0016] (2) Orange-red light encryption subunit: formed on adjacent mesa, which includes an electron transport layer, an organic long afterglow light emission layer, a hole transport layer, a hole injection layer and a transparent anode electrode deposited sequentially on the N-GaN layer;

[0017] The blue light communication subunit and the orange-red light encryption subunit share an N-type electrode as a common cathode and are each controlled by an independent drive circuit.

[0018] Among them, after receiving pulse electrical excitation from the independent driving circuit, the orange-red light encryption subunit's organic long afterglow light-emitting layer generates afterglow light with controllable decay characteristics after the excitation stops.

[0019] The time decay feature of the afterglow emission is used to perform time-domain encoding and encryption of information at the physical layer;

[0020] The blue light emission from the blue light communication subunit and the afterglow emission from the orange-red light encryption subunit mix in space to form a composite white light for lighting and communication.

[0021] Furthermore, the afterglow decay time constant (τ) of the organic long afterglow luminescent layer is controlled within the range of 1 μs to 100 ms by adjusting the pulsed electrical excitation parameters; the orange-red light encryption subunit controls the pulsed electrical excitation parameters so that the intensity of the afterglow emission at at least one preset moment corresponds to a predetermined information encoding state.

[0022] Furthermore, the blue light communication subunit and the orange-red light encryption subunit are monolithically integrated by selectively fabricating regions on the same epitaxial wafer; wherein, the organic long afterglow light emitting layer and transparent anode electrode of the orange-red light encryption subunit are formed by a masking vacuum evaporation process and are deposited only on the surface of the N-GaN layer in a predetermined mesa region.

[0023] Preferably, the In x Ga 1-x In the N / GaN multi-quantum-well active layer, x takes the value of 0.12 ~ 0.25, and the emission wavelength of the blue light communication sub-unit is 450 nm ~ 470 nm;

[0024] In the mesa array, each mesa has a feature size of 20 μm to 100 μm, the spacing between adjacent mesa is 5 μm to 20 μm, and the etching depth is 200 nm to 1.5 µm.

[0025] Furthermore, an electron injection layer is provided between the electron transport layer and the N-GaN layer; and an exciton blocking layer is provided between the organic long afterglow luminescent layer and the hole transport layer.

[0026] Specifically, the organic long-afterglow light-emitting layer includes a host material and a long-afterglow orange-red light doping material doped therein;

[0027] Preferably, the host material is selected from any one of 2,2',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (TPBi), polyvinylcarbazole (PVK), triphenylphosphine (PPT), 4,4'-bis(9-carbazole)biphenyl (CBP), 2,4-diphenyl-6-(3-(benzenesulfonyl)phenyl)-1,3,5-triazine (TRZ-SO2), 1,3-dicarbazolebenzene (mCP), and 2,8-bis(diphenylphosphoxy)dibenzofuran (PPF);

[0028] The long-afterglow orange-red light doped material is selected from any one of 2,6-dichloro-4-(2,6-dimethoxyphenyl)phenyl][3,5-dichloro-4-pyridyl)(2,4,6-trichlorophenyl)methyl radical (PyBTM-(Me2Res)), tetraphenylethylene-difluoroboron β-diketone-hydrogen (TPE-BF2-H), tetraphenylethylene-difluoroboron β-diketone-bromine-substituted derivative (TPE-BF2-Br), and hydroxyl derivative of rhodamine B (PU@TAED@RhOH);

[0029] The long-persistent orange-red light doped material has a persistence decay lifetime of 10 μs to 50 ms after the electrical excitation stops, and its doping mass concentration is 1% to 10%. This allows the initial persistence brightness (I0) and decay time constant (τ) of the organic long-persistent light-emitting layer to be independently controlled under pulsed current driving, so as to optimize the temporal coding density.

[0030] Furthermore, the electron injection layer material is selected from at least one of cesium carbonate (Cs2CO3) and lithium fluoride (LiF), and has a thickness of 0.5-1.5 nm;

[0031] The electron transport layer material is selected from at least one of 1,3,5-tris(m-pyridin-3-ylphenyl)benzene (TmPyPB), 2,4,6-tris[3-(diphenylphosphoxy)phenyl]-1,3,5-triazine (PO-T2T), and 4,7-diphenyl-1,10-phenanthroline (BPhen), and has a thickness of 30-70 nm;

[0032] The hole transport layer material is selected from at least one of 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC), 4,4',4''-tris(carbazole-9-yl)triphenylamine (TCTA), 4,4',4''-tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA), and poly(9-vinylcarbazole) (PVK), with a thickness of 40-70 nm;

[0033] The hole injection layer material is selected from at least one of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), molybdenum oxide (MoO3), and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HAT-CN), with a thickness of 2-40 nm;

[0034] The transparent anode electrode material is indium tin oxide (ITO) or metallic silver (Ag).

[0035] Furthermore, the white light communication μLED device with physical layer time-domain encryption function of the present invention also includes a programmable driver connected to the independent driving circuit; the programmable driver is configured to execute an encrypted communication method, including applying a first driving signal that modulates the main communication data to the blue light communication subunit; and applying a pulse sequence encoded according to the encryption information to the orange-red light encryption subunit to excite it to generate time-domain afterglow emission carrying the encryption information.

[0036] Furthermore, the present invention also claims a physical layer time-domain encryption method for the aforementioned white light communication μLED device, comprising: applying a first driving signal to the blue light communication subunit, the signal carrying main communication data; applying a second driving signal to the orange-red light encryption subunit, the signal being a current pulse sequence generated according to the encryption information; at least one of the amplitude, width, or interval of the pulse sequence is used to control the organic long-persistence light-emitting layer to emit afterglow light with a specific attenuation law, and the encryption information is incorporated into this attenuation curve; the second driving signal may include a synchronization pulse sequence for achieving the start alignment of the encryption information frame.

[0037] Furthermore, the present invention also claims a physical layer time-domain encrypted white light communication system, comprising:

[0038] The transmitting end includes the aforementioned white light communication μLED device with physical layer time-domain encryption function, and a drive control module for generating and outputting a first drive signal and a second drive signal; the first drive signal is applied to the blue light communication subunit, and the second drive signal is applied to the orange-red light encryption subunit.

[0039] The receiving / decryption end is configured as follows:

[0040] (1) Receive the composite white light signal and separate it into blue light signal and orange-red light signal;

[0041] (2) Demodulate the blue light signal to recover the main communication data;

[0042] (3) Extract and decode the time-domain features of the orange-red light signal to recover the encrypted information.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. Implement physical layer encryption from the light source hardware.

[0045] This invention utilizes the controllable light emission decay characteristics of organic long-afterglow materials to directly incorporate information into the temporal variation of optical signals. By adjusting the width and intensity of the electrical pulses, the brightness and duration of the afterglow can be controlled, thereby achieving optical signal encryption. In this way, communication security is guaranteed at the physical layer of the light-emitting device, avoiding the risks of traditional systems relying on software algorithms for encryption and being easily intercepted.

[0046] 2. Dual-channel collaborative transmission, communication and encryption are performed simultaneously.

[0047] The device of this invention uses a blue μLED as the main channel and an orange-red μLED as the encryption channel, both sharing a cathode and driven by independent anodes. The blue light is used for high-speed communication, while the orange-red light is responsible for encrypted information transmission. Both signals are emitted simultaneously within the same white light source, eliminating the need for additional time-division or frequency-division processing. This maintains the communication speed while improving transmission security.

[0048] 3. Monolithic integrated structure, simple manufacturing process and scalable.

[0049] This invention fabricates blue and orange-red μLED arrays on the same sapphire substrate, achieving region-selective evaporation through a masking technique. The entire process is compatible with existing LED production lines, eliminating the need for complex bonding or transfer steps. This design is easily scalable to large-scale arrays or on-chip optical communication systems, demonstrating feasibility for mass production and engineering applications.

[0050] 4. Combining high bandwidth and strong concealment

[0051] The blue light-emitting unit of this invention has a modulation bandwidth of hundreds of MHz to GHz, ensuring high-speed communication performance. The organic orange-red light unit continues to emit light after excitation stops, and the afterglow curve can be freely adjusted, resulting in strong signal concealment. Encrypted information is hidden in the afterglow tail, making it difficult to identify the specific code even if the light signal is intercepted externally, thereby improving anti-interference and anti-eavesdropping capabilities.

[0052] 5. Diverse application scenarios and high security value

[0053] The device of this invention can be applied to fields such as safety lighting, secure communication, IoT node authentication and low-power encrypted communication, providing an integrable hardware implementation approach for high-security visible light communication. Attached Figure Description

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0055] Figures 1-14 This is a cross-sectional structural diagram of a key step in the fabrication process of the device of the present invention.

[0056] Figure 15 This is a schematic diagram of the planar layout of a 2×2 pixel unit array.

[0057] Figure 16 This is a three-dimensional structural diagram of the device structure of the present invention.

[0058] Figure 17 This is a block diagram of an encrypted white light communication system based on the device of the present invention. Detailed Implementation

[0059] The present invention can be better understood from the following embodiments.

[0060] The fabrication process of the device described in this invention is compatible with the existing GaN-based LED chip manufacturing process and can be directly implemented on existing production lines.

[0061] The present invention relates to a white-light communication μLED device with physical layer time-domain encryption function, comprising:

[0062] Patterned sapphire substrate;

[0063] A III-nitride semiconductor epitaxial layer grown on the substrate, the epitaxial layer comprising, from bottom to top, a GaN buffer layer, an N-GaN layer, and an In layer. x Ga 1-x N / GaN multiple quantum well active layer and P-GaN layer;

[0064] An electrically isolated mesa array structure is etched onto the epitaxial layer, the mesa array penetrating the P-GaN layer and In. x Ga 1-x N / GaN multiple quantum well active layer and extended to N-GaN layer;

[0065] A P-type electrode is disposed on the P-GaN layer, and an N-type electrode is disposed on the N-GaN layer;

[0066] Each pair of adjacent surfaces constitutes an encrypted pixel unit, and the encrypted pixel unit includes:

[0067] (1) Blue light communication subunit: consisting of the In x Ga 1-x The structure consists of a III-nitride epitaxial layer of N / GaN multi-quantum-well structure, used to emit blue light signals as the main channel for high-speed communication.

[0068] (2) Orange-red light encryption subunit: formed on adjacent mesa, which includes an electron transport layer, an organic long afterglow light emission layer, a hole transport layer, a hole injection layer and a transparent anode electrode deposited sequentially on the N-GaN layer;

[0069] The blue light communication subunit and the orange-red light encryption subunit share an N-type electrode as a common cathode and are each controlled by an independent drive circuit.

[0070] Among them, after receiving pulse electrical excitation from the independent driving circuit, the orange-red light encryption subunit's organic long afterglow light-emitting layer generates afterglow light with controllable decay characteristics after the excitation stops.

[0071] The time decay feature of the afterglow emission is used to perform time-domain encoding and encryption of information at the physical layer;

[0072] The blue light emission from the blue light communication subunit and the afterglow emission from the orange-red light encryption subunit mix in space to form a composite white light for lighting and communication.

[0073] The following combination Figures 1 to 17 The technical solutions of the embodiments of the present invention will be clearly and completely described herein. It should be noted that the accompanying drawings are all schematic diagrams and are not drawn to scale; they are only used to illustrate the technical solutions.

[0074] 1. Device Structure

[0075] like Figure 1 As shown, the device of this invention is monolithically integrated on the same patterned sapphire substrate 1. The device consists of two parts: an inorganic III-nitride μLED subunit that emits blue light and an organic μLED subunit that emits orange-red light and has long afterglow characteristics. These two subunits are arranged side by side and can be independently addressed and driven. Through this integrated structure, the device can simultaneously realize three functions: illumination, communication, and physical layer encryption on a single chip.

[0076] 2. Structure and fabrication of inorganic blue light communication subunits

[0077] This subunit is based on a III-nitride semiconductor material. First, on a patterned sapphire substrate 1, a GaN buffer layer 2, an N-type GaN layer 3, and an In layer are sequentially epitaxially grown using metal-organic chemical vapor deposition (MOCVD). x Ga 1-x The active layer 4 consists of N / GaN multiple quantum wells (MQWs) and the P-type GaN layer 5. x Ga 1-x The N / GaN multi-quantum-well active layer was optimized for emitting blue light with a center wavelength of approximately 460-470 nm.

[0078] (1) The mesa array is etched on the surface of the wafer after epitaxial growth. First, a 200 nm thick SiO2 thin film 6 is deposited by plasma-enhanced chemical vapor deposition (PECVD) as a hard mask (e.g. Figure 2 Then, a regular array of square mesa-shaped surfaces (such as...) is formed on the SiO2 layer using ultraviolet lithography. Figure 3 , Figure 4 Using photoresist and subsequently deposited metal (such as Cr) as a composite mask, the pattern is transferred to the SiO2 layer using reactive ion etching (RIE). Then, using the patterned SiO2 as a mask, inductively coupled plasma (ICP) etching is employed to sequentially etch the P-GaN layer and In layer 5. x Ga 1-x N / GaN layers (MQWs) 4 up to N-GaN layers 3, forming a uniformly sized, electrically isolated mesa array (e.g. Figure 5 , Figure 6 After etching, the metal mask layer 8 and surface etching damage are removed by wet etching, and the remaining dielectric layer 6 is removed using hydrofluoric acid or BOE solution. Figure 7 ).

[0079] In the mesa array, the feature size of each mesa is 20 μm to 100 μm, the spacing between adjacent mesa is 5 μm to 20 μm, and the etching depth is 200 nm to 1.5 µm.

[0080] (2) Electrode preparation

[0081] On the mesa array, 200 nm SiO2 was deposited as the dielectric layer 6 using PECVD. After spin-coating photoresist 7 onto the SiO2, N-type electrode patterns (e.g., [image of N-type electrode pattern]) were formed on the photoresist using ultraviolet lithography with a photomask. Figure 8 Using photoresist 7 as a mask, the SiO2 dielectric layer 6 is etched using RIE to transfer the N-type electrode pattern to the N-GaN layer 3 (e.g., ...). Figure 9 Subsequently, 200-300 nm Cr / Al / Ni / Au was deposited using PVD evaporation as the N-type electrode 9 (common cathode). Acetone was used for ultrasonic lift-off of the photoresist 7 and the metal film on the photoresist layer. Figure 10 Finally, rapid thermal annealing in an N2 environment forms an ohmic contact.

[0082] Photoresist 7 was spin-coated again onto the sample surface, and a P-type electrode region was fabricated on the sample surface using ultraviolet lithography. Using photoresist 7 as a mask, the SiO2 dielectric layer 6 was etched by RIE, transferring the P-type electrode pattern to the P-GaN layer 5 (e.g., ...). Figure 11 ) PVD deposition of 150-300nm Ni / Au was used as the p-type electrode 10 (e.g. Figure 12The photoresist 7 and the metal film on the photoresist layer were removed using ultrasonic peeling with acetone. The sample was then washed and dried (e.g., ...). Figure 13 Finally, in an N2 environment, thermal annealing was used to achieve ohmic contacts in P-GaN, thus completing the blue Micro-LED pixel array structure.

[0083] At this point, the fabrication of the blue light communication sub-unit array is complete.

[0084] 3. Structure and preparation of organic orange-red optical encryption subunit

[0085] To achieve temporal encryption, organic electroluminescent units are constructed on adjacent mesa as orange-red light encryption subunits. This unit uses the exposed N-GaN layer 3 as a common cathode, and sequentially deposits an electron transport layer 11, an organic long afterglow luminescent layer 12, an exciton blocking layer 13, a hole transport layer 14, a hole injection layer 15, and a transparent anode electrode 16.

[0086] The sample preparation method is as follows: The sample with electrodes is placed in a multi-source organic vacuum evaporation system. A masking technique is used to deposit each organic functional layer and the top electrode only in designated areas (e.g., ...). Figure 14 ).

[0087] As a specific embodiment, the specific materials and parameters of each functional layer are as follows:

[0088] Electron injection layer: Lithium fluoride (LiF) vapor-deposited, with a thickness of 1 nm;

[0089] Electron transport layer 11: 1,3,5-tris(m-pyridin-3-ylphenyl)benzene (TmPyPB) was deposited by vapor deposition with a thickness of 50 nm;

[0090] Organic long afterglow luminescent layer 12: 4,4'-bis(9-carbazole)biphenyl (CBP) is used as the main material, and 10% of tetraphenylethylene-difluoroboron β-diketone-bromine-substituted derivative (TPE-BF2-Br) is used as the long afterglow luminescent material, with a thickness of 30 nm;

[0091] Exciton blocking layer 13: 2,8-bis(diphenylphosphoxy)dibenzofuran (PPF) was deposited by vapor deposition, with a thickness of 10 nm;

[0092] Hole transport layer 14: 4,4',4''-tris(carbazole-9-yl)triphenylamine (TCTA) was deposited by vapor deposition with a thickness of 60 nm;

[0093] Hole injection layer 15: Molybdenum oxide (MoO3) vapor-deposited, with a thickness of 10 nm;

[0094] Transparent anode electrode 16: sputtered indium tin oxide (ITO) with a thickness of 100 nm.

[0095] This process enables region-selective integration of inorganic blue μLEDs and organic orange-red μLEDs on the same epitaxial wafer, without the need for bonding or transfer steps.

[0096] 4. Integrated structural features and array layout

[0097] The final device structure is as follows Figure 14 As shown, its three-dimensional schematic diagram is as follows: Figure 16 The two sub-units share an N-type electrode 9 as a common cathode, while the anodes are driven independently. The blue light unit emits a communication signal (first driving signal), and the orange-red light unit emits an encryption signal (second driving signal). The two signals are superimposed in space to form a composite white light output.

[0098] Encrypted pixel units can be arranged in different ways depending on application requirements. For example... Figure 15 As shown, the 2×2 array structure includes blue μLED20, orange-red μLED21, and spare units 22 and 23 for process tolerance, brightness compensation, or functional expansion. Another compact configuration is shown below. Figure 16 As shown, a 2×1 pixel unit is used, containing only one blue μLED17 and one orange-red μLED18. All units are arranged in parallel, enabling a higher pixel density. This compact layout is suitable for point-to-point secure communication or on-chip encrypted transmission systems.

[0099] 5. Physical Layer Encrypted Communication Methods and System Implementation

[0100] Based on the μLED device of this invention, a physical layer time-domain encrypted white light communication system can be constructed. For example... Figure 17 As shown, the system consists of a transmitter and a receiver.

[0101] (1) Transmitter end

[0102] The transmitter mainly consists of μLED devices and a programmable driver module, and its working process is as follows:

[0103] The main channel drives the blue light unit for transmitting main communication data. This data can be modulated using OFDM or PAM-n to generate a broadband signal, which is then amplified and loaded onto a P-type electrode to achieve high-speed light intensity modulation.

[0104] An encrypted channel drives an orange-red light unit for transmitting encrypted information. The system converts binary information into current pulses of varying amplitudes, widths, or intervals, which are then applied to the transparent anode. Different pulse parameters alter the brightness I0 and decay time constant τ of the organic long afterglow layer. The decay time constant τ is modulated within the range of 1 μs to 100 ms.

[0105] After the pulse stops, the orange-red light unit produces a controllable afterglow, and its time-domain decay curve carries encrypted information.

[0106] Blue light and orange-red light signals are spatially superimposed to output a stable composite white light. This signal simultaneously carries communication data and time-domain encrypted information.

[0107] (2) Receiving end

[0108] The receiving end includes a beam splitting system, a photodetector, and a signal processing unit.

[0109] The composite white light is focused by a lens and then enters the dichroic beam splitter module. The blue light channel (450–470 nm) is used for communication data extraction, and the orange-red light channel (≥550 nm) is used for encrypted signal analysis.

[0110] The blue light signal is processed by a high-speed APD detector and demodulator to recover the communication data.

[0111] The orange-red light signal is received by a photomultiplier tube or a single-photon detector and then digitized. The signal processing module extracts the afterglow curve features.

[0112] The system pre-stores reference attenuation curves for different encrypted information bits. The receiving end matches and analyzes the measured curves against the reference templates. The bits corresponding to the template with the highest matching degree are the decoding results.

[0113] In simplified mode, the afterglow intensity I(t1) can also be sampled at a fixed time t1 and compared with the threshold I. th Comparison: If I(t1) ≥ I th If the result is positive, it is judged as "1"; otherwise, it is judged as "0".

[0114] t1 and I th The setting depends on the transmitter pulse parameters and the τ–I0 characteristics of the long afterglow material.

[0115] For multi-bit frames, a synchronization pulse can be added before the pulse sequence for frame start identification and time calibration.

[0116] This invention provides a white-light communication μLED device with physical layer time-domain encryption function, as well as its encryption method and system. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A white-light communication μLED device with physical layer time-domain encryption function, characterized in that, include: Patterned sapphire substrate; A III-nitride semiconductor epitaxial layer grown on the substrate, the epitaxial layer comprising, from bottom to top, a GaN buffer layer, an N-GaN layer, and an In layer. x Ga 1-x N / GaN multiple quantum well active layer and P-GaN layer; An electrically isolated mesa array structure is etched onto the epitaxial layer, the mesa array penetrating the P-GaN layer and In. x Ga 1-x N / GaN multiple quantum well active layer and extended to N-GaN layer; A P-type electrode is disposed on the P-GaN layer, and an N-type electrode is disposed on the N-GaN layer; Each pair of adjacent surfaces constitutes an encrypted pixel unit, and the encrypted pixel unit includes: (1) Blue light communication subunit: consisting of the In x Ga 1-x The structure consists of a III-nitride epitaxial layer of N / GaN multi-quantum-well structure, used to emit blue light signals as the main channel for high-speed communication. (2) Orange-red light encryption subunit: formed on adjacent mesa, which includes an electron transport layer, an organic long afterglow light emission layer, a hole transport layer, a hole injection layer and a transparent anode electrode deposited sequentially on the N-GaN layer; The blue light communication subunit and the orange-red light encryption subunit share an N-type electrode as a common cathode and are each controlled by an independent drive circuit. After receiving pulsed electrical excitation from the independent driving circuit, the orange-red light encryption subunit's organic long-afterglow light-emitting layer produces afterglow light with controllable decay characteristics after the excitation stops. The time decay feature of the afterglow emission is used to perform time-domain encoding and encryption of information at the physical layer; The blue light emission from the blue light communication subunit and the afterglow emission from the orange-red light encryption subunit mix in space to form a composite white light for lighting and communication.

2. The white LED communication device with physical layer time-domain encryption function according to claim 1, characterized in that, The afterglow decay time constant (τ) of the organic long afterglow luminescent layer is controlled within the range of 1 μs to 100 ms by adjusting the pulsed electrical excitation parameters; the orange-red light encryption subunit controls the pulsed electrical excitation parameters so that the intensity of the afterglow emission at at least one preset moment corresponds to a predetermined information encoding state.

3. The white LED communication device with physical layer time-domain encryption function according to claim 1, characterized in that, The blue light communication subunit and the orange-red light encryption subunit are monolithically integrated by selectively fabricating regions on the same epitaxial wafer; wherein, the organic long afterglow light emitting layer and transparent anode electrode of the orange-red light encryption subunit are formed by a masking vacuum evaporation process and are deposited only on the surface of the N-GaN layer in a predetermined mesa region.

4. The white LED communication device with physical layer time-domain encryption function according to claim 1, characterized in that, The In x Ga 1-x In the N / GaN multi-quantum-well active layer, x takes the value of 0.12 ~ 0.25, and the emission wavelength of the blue light communication sub-unit is 450 nm ~ 470 nm; In the mesa array, each mesa has a feature size of 20 μm to 100 μm, the spacing between adjacent mesa is 5 μm to 20 μm, and the etching depth is 200 nm to 1.5 µm.

5. The white-light communication μLED device with physical layer time-domain encryption function according to claim 1, characterized in that, An electron injection layer is provided between the electron transport layer and the N-GaN layer; an exciton blocking layer is provided between the organic long afterglow luminescent layer and the hole transport layer.

6. The white-light communication μLED device with physical layer time-domain encryption function according to claim 1, characterized in that, The organic long-afterglow light-emitting layer includes a host material and a long-afterglow orange-red light doping material doped therein; The main material is selected from any one of 2,2',2''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (TPBi), polyvinylcarbazole (PVK), triphenylphosphine (PPT), 4,4'-bis(9-carbazole)biphenyl (CBP), 2,4-diphenyl-6-(3-(benzenesulfonyl)phenyl)-1,3,5-triazine (TRZ-SO2), 1,3-dicarbazolebenzene (mCP), and 2,8-bis(diphenylphosphoxy)dibenzofuran (PPF); The long-afterglow orange-red light doped material is selected from any one of 2,6-dichloro-4-(2,6-dimethoxyphenyl)phenyl][3,5-dichloro-4-pyridyl)(2,4,6-trichlorophenyl)methyl radical (PyBTM-(Me2Res)), tetraphenylethylene-difluoroboron β-diketone-hydrogen (TPE-BF2-H), tetraphenylethylene-difluoroboron β-diketone-bromine-substituted derivative (TPE-BF2-Br), and hydroxyl derivative of rhodamine B (PU@TAED@RhOH); The long-persistent orange-red light doped material has a persistence decay lifetime of 10 μs to 50 ms after the electrical excitation stops, and its doping mass concentration is 1% to 10%. This allows the initial persistence brightness (I0) and decay time constant (τ) of the organic long-persistent light-emitting layer to be independently controlled under pulsed current driving, so as to optimize the temporal coding density.

7. The white light communication μLED device with physical layer time-domain encryption function according to claim 5, characterized in that, The electron injection layer material is selected from at least one of cesium carbonate (Cs2CO3) and lithium fluoride (LiF), and has a thickness of 0.5-1.5 nm; The electron transport layer material is selected from at least one of 1,3,5-tris(m-pyridin-3-ylphenyl)benzene (TmPyPB), 2,4,6-tris[3-(diphenylphosphoxy)phenyl]-1,3,5-triazine (PO-T2T), and 4,7-diphenyl-1,10-phenanthroline (BPhen), and has a thickness of 30-70 nm; The hole transport layer material is selected from at least one of 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC), 4,4',4''-tris(carbazole-9-yl)triphenylamine (TCTA), 4,4',4''-tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA), and poly(9-vinylcarbazole) (PVK), with a thickness of 40-70 nm; The hole injection layer material is selected from at least one of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), molybdenum oxide (MoO3), and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HAT-CN), with a thickness of 2-40 nm; The transparent anode electrode material is indium tin oxide (ITO) or metallic silver (Ag).

8. The white-light communication μLED device with physical layer time-domain encryption function according to claim 1, characterized in that, It also includes a programmable driver connected to the independent drive circuit; the programmable driver is configured to perform an encrypted communication method, including applying a first drive signal that modulates the main communication data to the blue light communication subunit; and applying a pulse sequence encoded according to the encrypted information to the orange-red light encryption subunit to excite it to generate time-domain afterglow emission carrying the encrypted information.

9. The physical layer time-domain encryption method for the white light communication μLED device according to claim 1, characterized in that, include: A first drive signal carrying main communication data is applied to the blue light communication subunit; A second driving signal is applied to the orange-red light encryption subunit. This signal is a sequence of current pulses generated based on the encryption information. At least one of the amplitude, width, or interval of the pulse sequence is used to control the organic long afterglow light-emitting layer to emit afterglow light with a specific attenuation law. The encryption information is then incorporated into this attenuation curve. The second driving signal may include a synchronization pulse sequence for achieving the initial alignment of the encryption information frame.

10. A physical layer time-domain encrypted white light communication system, characterized in that, include: The transmitting end includes a white light communication μLED device with physical layer time-domain encryption function as described in any one of claims 1-8, and a drive control module for generating and outputting a first drive signal and a second drive signal; The first driving signal is applied to the blue light communication subunit, and the second driving signal is applied to the orange-red light encryption subunit; The receiving / decryption end is configured as follows: (1) Receive the composite white light signal and separate it into blue light signal and orange-red light signal; (2) Demodulate the blue light signal to recover the main communication data; (3) Extract and decode the time-domain features of the orange-red light signal to recover the encrypted information.

Images