Free space optical communication method and device and electronic equipment
By splitting and modulating the initial optical signal in a free-space optical communication system, a target beam with stable concurrency is generated, which solves the signal distortion problem caused by atmospheric turbulence, improves communication performance, and is suitable for high-speed communication.
Patent Information
- Application Number
- CN202511784739.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-01
- Publication Date
- 2026-02-24
AI Technical Summary
Existing free-space optical communication technologies suffer from severe signal distortion in turbulent atmospheric environments, leading to a decline in communication performance.
An electro-optic modulation component is used to split the initial optical signal to generate first and second polarized optical signals that are orthogonal to each other. After being modulated by the electro-optic modulation component, the signals are combined to generate the target beam. The receiving end determines the information by measuring the concurrency of the beam.
It improves the anti-turbulence transmission capability of free-space optical communication systems, realizes dynamic adjustment of beam vector properties, is suitable for integration with on-chip optical platforms and quantum optical paths, and meets the requirements of high-speed communication.
Smart Images
Figure CN121567211A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of free-space optical communication technology, and more specifically, to a free-space optical communication method, apparatus, and electronic device. Background Technology
[0002] Free-space optical communication technology has become a research focus in the field of optical communication due to its advantages such as wide bandwidth, good directivity, and strong resistance to electromagnetic interference. It is widely used in satellite communication, terrestrial communication, and military fields.
[0003] Current free-space optical communication technology mainly uses a fundamental Gaussian beam as a carrier laser for signal transmission, utilizing the amplitude and phase of the optical signal as modulation dimensions. However, in free space, the amplitude and phase of the optical signal are affected by intensity flicker and wavefront distortion caused by atmospheric turbulence, which leads to distortion of the receiver signal during detection and reduces communication performance. Summary of the Invention
[0004] In order to at least overcome the above-mentioned deficiencies in the prior art, the purpose of this application is to provide a free space optical communication method, apparatus and electronic device.
[0005] In a first aspect, embodiments of this application provide a free-space optical communication method applied to a free-space optical communication system, the free-space optical communication system including a transmitter, a receiver, and a free-space channel, the transmitter and the receiver being connected through the free-space channel; the transmitter includes an electro-optic modulation component; The free-space optical communication method includes: The transmitting end acquires an initial optical signal and performs beam splitting processing on the initial optical signal to obtain a first polarized optical signal and a second polarized optical signal, wherein the polarization states of the first polarized optical signal and the second polarized optical signal are mutually orthogonal. The first polarized light signal and the second polarized light signal are modulated by the electro-optic modulation component of the transmitting end, and the modulated first polarized light signal and the second polarized light signal are combined to obtain the target beam. The transmitting end transmits the target beam to the receiving end through a free-space channel; The receiving end receives the target beam and determines the concurrency level corresponding to the target beam, wherein the concurrency level is used to determine the information carried by the target beam.
[0006] In one possible implementation, the electro-optic modulation component includes a first modulation branch and a second modulation branch; The step of modulating the first polarized light signal and the second polarized light signal using the electro-optic modulation component at the transmitting end includes: A first radio frequency voltage signal and a second radio frequency voltage signal are respectively applied to the first modulation branch and the second modulation branch of the electro-optic modulation component, wherein the first radio frequency voltage signal and the second radio frequency voltage signal are pulse amplitude modulation signals with different level intervals; The first polarized light signal is modulated through the first modulation branch, and the second polarized light signal is modulated through the second modulation branch.
[0007] In one possible implementation, the first radio frequency voltage signal V H Obtained through the following methods:
[0008] The second radio frequency voltage signal V V Obtained through the following methods:
[0009] in, , , t H The intensity transfer function represents the light intensity of the first polarized light signal; t V The intensity transfer function represents the light intensity of the second polarized light signal. , C represents concurrency; V π Indicates half-wave voltage; This represents the static residual phase difference between the two arms. This indicates the bias voltage.
[0010] In one possible implementation, the transmitting end further includes a first spiral phase plate and a second spiral phase plate; The step of combining the modulated first polarized light signal and the second polarized light signal to obtain the target beam includes: The modulated first polarized light signal is converted into a first Gaussian Laguerre beam through the first spiral phase plate; and the modulated second polarized light signal is converted into a second Gaussian Laguerre beam through the second spiral phase plate, wherein the topological charge of the first spiral phase plate is opposite to that of the second spiral phase plate. The first Gaussian Laguerre beam and the second Gaussian Laguerre beam are combined to obtain the target beam.
[0011] In one possible implementation, the step of the receiving end receiving the target beam and determining the concurrency level corresponding to the target beam includes: The receiving end receives the target beam and performs beam splitting on the target beam to obtain a horizontally polarized beam, a vertically polarized beam, a diagonally polarized beam, and a right-hand circularly polarized beam. Electrical signals were acquired from the horizontally polarized beam, the vertically polarized beam, the diagonally polarized beam, and the right-hand circularly polarized beam to obtain the measured values of horizontal polarization power, vertical polarization power, diagonal polarization power, and right-hand circular polarization power. The concurrency of the target beam is determined based on the measured values of horizontal polarization power, vertical polarization power, diagonal polarization power, and right-hand circular polarization power.
[0012] In one possible implementation, the concurrency level corresponding to the target beam is obtained in the following way:
[0013] Among them, P V P H P D P R These represent the horizontal polarization power measurement value, the vertical polarization power measurement value, the diagonal polarization power measurement value, and the right-hand circular polarization power, respectively.
[0014] In one possible implementation, the step of combining the modulated first polarized light signal and the second polarized light signal to obtain the target beam includes: The modulated first polarized light signal and the second polarized light signal are combined to obtain an initial combined beam. By adjusting the coupling strength between the polarization and spatial mode of the initial combined beam, information encoding is performed on the initial combined beam to obtain a target beam carrying information.
[0015] Secondly, embodiments of this application also provide a free-space optical communication device, applied to a free-space optical communication system, the free-space optical communication system including a transmitter, a receiver, and a free-space channel, the transmitter and the receiver being connected through the free-space channel; the transmitter includes an electro-optic modulation component; The free-space optical communication device includes: A beam splitting module is used to acquire an initial optical signal and perform beam splitting processing on the initial optical signal to obtain a first polarized optical signal and a second polarized optical signal, wherein the polarization states of the first polarized optical signal and the second polarized optical signal are mutually orthogonal. The modulation module is used to modulate the first polarized light signal and the second polarized light signal, and to combine the modulated first polarized light signal and the second polarized light signal to obtain the target beam. A transmitting module is used to transmit the target beam to a receiving end via a free-space channel; A determining module is used to receive the target beam and determine the concurrency degree corresponding to the target beam, wherein the concurrency degree is used to determine the information carried by the target beam.
[0016] Thirdly, embodiments of this application also provide an electronic device, including: Memory, used to store one or more programs; A processor, when the one or more programs are executed by the processor, implements the free-space optical communication method provided in the first aspect above.
[0017] Fourthly, embodiments of this application also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the free-space optical communication method provided in the first aspect.
[0018] Based on any of the above aspects, the free-space optical communication method, apparatus, and electronic device provided in the embodiments of this application can dynamically adjust the vector nature of the light beam by performing beam splitting processing on the initial optical signal and modulating processing on the first polarized light signal and the second polarized light signal after beam splitting processing, and can also improve the anti-turbulence transmission capability of the free-space optical communication system. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings required in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the free-space optical communication system provided in this embodiment; Figure 2 This is a flowchart illustrating the free-space optical communication method provided in this embodiment; Figure 3 This is one of the schematic diagrams of a sub-step of step S200 provided in this embodiment; Figure 4 This is a schematic diagram of the target beam structure provided in this embodiment; Figure 5a The waveform of the non-uniform PAM4 level signal provided in this embodiment; Figure 5b Eye diagram of the non-uniform PAM4 level signal provided in this embodiment; Figure 6 This is the second schematic diagram of a sub-step of step S200 provided in this embodiment; Figure 7This is one of the schematic diagrams of a sub-step of step S400 provided in this embodiment; Figure 8 This is a schematic diagram of the receiver provided in this embodiment; Figure 9 This is the third schematic diagram of a sub-step of step S200 provided in this embodiment; Figure 10 This is a schematic diagram of the structure of the electronic device provided in this embodiment; Figure 11 This is a schematic diagram of the free-space optical communication device provided in this embodiment.
[0021] Icons: 100 - Transmitter; 110 - Electro-optic modulation assembly; 200 - Receiver; 210 - Optical metasurface; 220 - Photodetector array chip; 230 - Analog-to-digital converter for acquisition equipment; 300 - Free-space channel; 800 - Electronic device; 810 - Processor; 820 - Computer-readable storage medium; 830 - Free-space optical communication device; 831 - Beam splitter module; 832 - Modulation module; 833 - Transmitter module; 834 - Determining module. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0023] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0024] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0025] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0026] It should be noted that, where there is no conflict, different features in the embodiments of this application can be combined with each other.
[0027] The inventors discovered that vector beams are a type of non-uniformly polarized light field in space whose polarization state varies with position. Due to their non-uniform polarization distribution, their vector topology exhibits a certain degree of resistance to complex media such as atmospheric turbulence, making them applicable to fields such as free-space optical communication (FSO), optical manipulation, optical imaging, quantum communication, and multidimensional coding. In existing technologies, vector beam generation methods mainly include: using spatial phase patterns loaded with spatial light modulators (SLMs) and digital micromirrors (DMDs) to achieve polarization spatial manipulation; using solid-state devices such as q-plates and polarization converters (PCCs) for mode conversion; and generating Jones vector structures by superimposing polarized light with spatial modes.
[0028] However, the aforementioned methods suffer from high system complexity, insufficient control flexibility, or high device costs. For example, devices such as spatial light modulators (SLMs) and digital micromirrors (DMDs) have slow response speeds, failing to meet the demands of high-speed communication or real-time optical field control. Solid-state devices such as q-plates and polarization converters (PCCs) have fixed output modes, lacking dynamism. Furthermore, the generation method of Jones vector structures is limited by fixed combinations of polarization states and spatial modes, making it difficult to achieve dynamic and precise control of the vector quality factor (VQF). In addition, multi-device stacking structures are not conducive to integration and can easily lead to a decrease in system stability.
[0029] In view of this, this embodiment provides a solution that can solve the above problems. The solution provided in this embodiment will be described in detail below.
[0030] This application provides a free-space optical communication method, which can be applied to free-space optical communication systems. Please refer to... Figure 1The free-space optical communication system may include a transmitter 100, a receiver 200, and a free-space channel 300, with the transmitter 100 and receiver 200 connected via the free-space channel 300. The transmitter 100 may include an electro-optic modulation component 110.
[0031] Because vector beams possess a degree of inseparability in their spatial and polarization degrees of freedom, which can be quantized using entanglement (concurrency), also known as vector quality factor (VQF), the following optical field combinations can serve as the basis for modulation coding:
[0032] in, It can represent a light field. and It can represent any pair of orthogonal spatial patterns (such as OAM patterns). ), and It can represent a horizontal (vertical) linear polarization basis, and 'a' can represent the polarization component weighting parameter. This is used to adjust the vector quality factor (VQF), and the light intensity is normalized to... .
[0033] The concurrency C of the above light field can be calculated in the following way:
[0034] The above formula can be simplified to: The polarization component weighting parameter 'a' allows C to monotonically vary from a minimum value C = 0 (representing a completely scalar field (uniform polarization)) to a maximum value C = 1 (representing a field with maximum inseparability of space and polarization (non-uniform polarization)). The required amplitude modulation can be calculated as follows:
[0035] Therefore, information encoding can be performed by adjusting the coupling strength 'a' between polarization and spatial mode.
[0036] Since atmospheric turbulence disturbances primarily cause phase distortion through refractive index fluctuations, and these fluctuations are scalar (isotropic) and do not produce direction-dependent modulation of the polarization state, while the effect of refractive index changes on polarization is usually negligible, when a beam passes through a perturbed medium such as atmospheric turbulence, the disturbance only affects the spatial mode (e.g., causing phase distortion). The optical field concurrency after passing through the atmospheric channel (including propagation to the far field) can be calculated in the following way:
[0037] in, It can represent the concurrency of the light field after perturbation. It can represent the optical field after phase perturbation. F can represent the optical field propagating in the far field after phase perturbation. F can represent the Fourier transform operator that maps the optical field mode to the far field. F is a unitary transform, therefore:
[0038] Concurrency after perturbation It can be calculated in the following way:
[0039] in,
[0040] therefore, That is, the unitary transformation (phase perturbation caused by turbulence) only changes the appearance of the spatial pattern (such as the far-field distribution), but does not change the entanglement between the spatial pattern and polarization distribution of the vector beam, which shows that the concurrency C is not affected by atmospheric turbulence.
[0041] Furthermore, while both C and a range from 0 to 1, the invariance of C allows it to be used as a basis for multi-bit encoding. This is because all measurements of C will be consistent regardless of detector type or channel conditions, stemming from its property of quantum inheritance. This contrasts sharply with directly measuring the amplitude a, where varying detector sensitivities, efficiencies, and channel noise mean that a cannot achieve a universally consistent value. Consequently, the full multi-bit bandwidth from 0 to 1 is reduced to only 0 or 1 (one bit), regardless of whether there is light or no light.
[0042] In order to use the measurement value of C as the coding benchmark, it is possible to use... As an interval, with As the number of elements in the reference, it can be transmitted. Each bit. After spatial transmission, although the spatial mode structure becomes out of order and generates high modal crosstalk, the vector nature remains unchanged and there is no crosstalk. Therefore, it can be used as a reference for multi-bit coding.
[0043] Please refer to Figure 2 , Figure 2 This embodiment provides a schematic flowchart of a free-space optical communication method, which can be applied to... Figure 1The free-space optical communication system and method shown may include the following steps.
[0044] In step S100, the transmitting end 100 acquires an initial optical signal and performs beam splitting processing on the initial optical signal to obtain a first polarized optical signal and a second polarized optical signal, wherein the polarization states of the first polarized optical signal and the second polarized optical signal are mutually orthogonal.
[0045] In this embodiment, please refer again. Figure 1 The transmitter 100 may further include a continuous laser (CW), a polarization controller (PC), and a fiber polarization beam splitter (fPBS). The laser emitted by the CW is converted into an initial optical signal after passing through the PC. This initial optical signal is +45° linearly polarized light. Then, the fPBS can split the initial optical signal to obtain a first polarized optical signal and a second polarized optical signal. The first polarized optical signal can be an x-polarized optical signal, and the second polarized optical signal can be a y-polarized optical signal.
[0046] Specifically, a fiber polarization beam splitter (fPBS) can directly split an initial optical signal into an x-polarized light signal and a y-polarized light signal using the birefringence effect of an optical crystal, where the intensity ratio of the x-polarized light signal to the y-polarized light signal can be 1:1. Since the polarization states of the x-polarized light signal and the y-polarized light signal are orthogonal, the problem of unstable light intensity in interference light caused by changes in polarization state can be avoided.
[0047] For the initial optical signal after adjusting the polarization direction to +45°, its corresponding Jones vector is:
[0048] in, It can represent the amplitude of the light field. It can represent the optical angular frequency, where the two orthogonal components of the initial optical signal have equal intensity and no phase difference.
[0049] In step S200, the first polarized light signal and the second polarized light signal are modulated by the electro-optic modulation component 110 of the transmitter 100, and the modulated first polarized light signal and the second polarized light signal are combined to obtain the target beam.
[0050] In this embodiment, please refer again. Figure 1The first polarized light signal and the second polarized light signal obtained in step S100 can be input into the electro-optic modulation component 110 to achieve adjustable amplitude control. After the electro-optic modulation component 110 modulates the first polarized light signal and the second polarized light signal respectively, the modulated first polarized light signal and the second polarized light signal can be input into the polarization beam combiner (PBC) for beam combining to obtain the target beam.
[0051] In some examples, the electro-optic modulation component 110 can be a Mach-Zehnder (MZM) modulator.
[0052] In step S300, the transmitting end 100 transmits the target beam to the receiving end 200 through the free space channel 300.
[0053] In this embodiment, please refer again. Figure 1 The target beam obtained in step S200 can be emitted through the first telescope (Tel.1) to the free space channel 300, and then transmitted to the receiver 200.
[0054] In step S400, the receiving end 200 receives the target beam and determines the concurrency degree corresponding to the target beam, wherein the concurrency degree is used to determine the information carried by the target beam.
[0055] In this embodiment, when the target beam is transmitted to the receiver 200, it can be received by the optical antenna, then the target beam is measured and the corresponding concurrency of the target beam is calculated, thereby decoding the transmitted bits and recovering the information carried by the target beam.
[0056] Based on the above design, in the free-space optical communication method provided in this embodiment, by performing beam splitting processing on the initial optical signal and modulating processing on the first polarized optical signal and the second polarized optical signal after beam splitting processing, the vector nature of the beam can be dynamically adjusted, and the anti-turbulence transmission capability of the free-space optical communication system can also be improved.
[0057] In addition, the free-space optical communication method provided in this embodiment does not require a complex spatial light modulation structure, but only requires electro-optic devices and polarization optical paths, making it suitable for on-chip optical platforms, quantum optical paths or metasurface integration.
[0058] In one possible implementation, please refer again. Figure 1 The electro-optic modulation component 110 may include a first modulation branch and a second modulation branch. Both the first modulation branch and the second modulation branch may be Mach-Zehnder (MZM) modulators.
[0059] After the initial optical signal is split, it can be divided into two beams polarized along the x-axis. Components and polarization along the y-axis Quantity. Components and After the components are modulated by the first modulation branch and the second modulation branch of the electro-optic modulation component 110, the resulting square polarization distribution is determined by the first radio frequency voltage signal and the second radio frequency voltage signal applied to the first modulation branch and the second modulation branch.
[0060] Output light intensity of electro-optic modulation component 110 and input light intensity The relationship is:
[0061] in, It can represent the phase difference between the two arms. Controlled by the applied voltage. Input light intensity. The value can be 1.
[0062] Phase difference It can be calculated in the following way:
[0063] in, and This can represent the voltage supplied to the electro-optic modulation component 110. These are the bias voltages of each branch. It is the applied radio frequency voltage, V π1 and V π2 It can represent half-wave voltage, that is, the voltage required for the phase difference to reach π. In general, .
[0064] Therefore, the expression for transmittance is defined as follows:
[0065] To achieve intensity normalization and generate vector light with an accurate C-value, modulation is required using a first modulation branch and a second modulation branch, with the output intensity of the first modulation branch being independently controlled. Output light intensity of the second modulation branch .
[0066] Please refer to Figure 3 Step S200 may include the following sub-steps.
[0067] Step S211: Apply a first radio frequency voltage signal and a second radio frequency voltage signal to the first modulation branch and the second modulation branch of the electro-optic modulation component 110, respectively, wherein the first radio frequency voltage signal and the second radio frequency voltage signal are pulse amplitude modulation signals with different level intervals.
[0068] Step S212: Modulate the first polarized light signal through the first modulation branch, and modulate the second polarized light signal through the second modulation branch.
[0069] For the horizontal polarization branch (first modulation branch), when the dual-drive push-pull Mach-Zehnder modulator is operating at the Q+ point, we have:
[0070] make ,have Then we have:
[0071] If the orthogonal point is set to Q+, then , ,have .
[0072] Based on the relationship between the light intensity transfer function and C and a, the transfer functions of the H and V components can be calculated as follows:
[0073] Therefore, for a dual-drive push-pull Mach-Zehnder modulator, let Then, according to C, we get Then solve The first radio frequency voltage signal V H (t) can be calculated in the following way:
[0074] Among them, V π Indicates half-wave voltage; This represents the static residual phase of both arms; C represents the bias voltage; C represents the concurrency level.
[0075] Similarly, for the vertical polarization branch (the second modulation branch), we can obtain:
[0076] Among them, V π Indicates half-wave voltage; This represents the static residual phase of both arms; C represents the bias voltage; C represents the concurrency level.
[0077] Due to the first radio frequency voltage signal V H Second radio frequency voltage signal V V The arccos function in the signal is a monotonically decreasing function, and a unique C value corresponds to a unique V value. Therefore, the first radio frequency voltage signal V can be used...H Second radio frequency voltage signal V V The calculation formula applies the first radio frequency voltage signal and the second radio frequency voltage signal to the first modulation branch and the second modulation branch respectively. The optical fields after combining the modulated first polarized light signal and the second polarized light signal have different concurrency C.
[0078] However, the concurrency C and the first radio frequency voltage signal V H Second radio frequency voltage signal V V It is an inverse cosine function relationship. Therefore, if multiple equally spaced C values are required as encoding, the corresponding voltages are not linearly equally spaced. So, conventional linear pulse amplitude modulation signals cannot be used directly as driving signals. A nonlinear mapping LUT (lookup table) is needed to map the symbol bits to non-equally spaced levels.
[0079] In some examples, please refer to Figure 4 The target beam can be The beam has four vector quality factors. If the first and second radio frequency voltage signals applied to the first and second modulation branches are non-uniform PAM4 level signals (half-wave voltage)... =6.5V), please refer to Figure 5a and Figure 5b , Figure 5a Example: This embodiment provides a method for regulating... The waveform of a non-uniform PAM4 level signal with polarization components. Figure 5b Example: This embodiment provides a method for regulating... Eye diagram of a non-uniform PAM4 level signal with polarization component. It can be seen that the distribution characteristics of the non-uniform PAM4 level signal can effectively adapt to the nonlinear relationship between concurrency C and voltage, thereby achieving precise control of the polarization component. When C=0, the target beam is linearly polarized light; at this time, a=1, and the first RF voltage signal V... H =-3.25V, second radio frequency voltage signal V V =3.25V; when C=0.33, the target beam is the corresponding partial vector beam, at which point a=0.9714, and the first radio frequency voltage signal V H =-2.5469V, second radio frequency voltage signal V V =2.5469V; when C=0.66, the target beam is the corresponding partial vector beam, at which point a=0.8727, and the first radio frequency voltage signal V H =-1.7402V, second radio frequency voltage signal V V =1.7402V; When C=1, the target beam is a fully vector-polarized beam, at which point a=0.5, and the first radio frequency voltage signal V H=0V, second radio frequency voltage signal V V =0V.
[0080] Specifically, to ensure the maximization of the Euclidean distance between adjacent concurrency levels C, the interval of C can be fine-tuned. Then, a non-uniform pulse amplitude modulation signal can be directly generated using a digital signal processing algorithm (DSP) and an analog-to-digital converter (DAC) (by pre-programming voltage values and calibrating the output accuracy of the DAC). Alternatively, if only a uniform pulse amplitude modulation signal can be generated, pre-distortion is required at the digital end to compensate for the nonlinearity of the arccos function. Then, based on the first RF voltage signal V... H Second radio frequency voltage signal V V The calculation formula modulates the H component and V component through the first modulation branch and the second modulation branch of the electro-optic modulation component 110, respectively, and finally outputs the polarization beam combiner.
[0081] In the above design, by dynamically adjusting the light intensity ratio of the first modulation branch and the second modulation branch using pulse amplitude modulation signals with different level intervals, nanosecond-level rapid switching of the vector quality factor (VQF) can be achieved, thereby meeting the requirements of high-speed optical communication.
[0082] In one possible implementation, the transmitter 100 may further include a first spiral phase plate (SPP1) and a second spiral phase plate (SPP2).
[0083] Please refer to Figure 6 Step S200 may also include the following sub-steps.
[0084] Step S221: The modulated first polarized light signal is converted into a first Gaussian Laguerre beam through the first spiral phase plate (SPP1); and the modulated second polarized light signal is converted into a second Gaussian Laguerre beam through the second spiral phase plate (SPP2), wherein the topological charge of the first spiral phase plate (SPP1) is opposite to the topological charge of the second spiral phase plate (SPP2).
[0085] In this embodiment, please refer again. Figure 1 After modulating the first polarized light signal and the second polarized light signal, the modulated first polarized light signal can be converted into a first Gaussian beam by the first collimator (Col.1), and the modulated second polarized light signal can be converted into a second Gaussian beam by the second collimator (Col.2). Then, the first Gaussian beam is converted into a first Gaussian Laguerre beam by the first spiral phase plate (SPP1). The second Gaussian beam is converted into a second Gaussian Laguerre beam via the second spiral phase plate (SPP2). In this configuration, the topological charge of the first spiral phase plate (SPP1) is opposite to that of the second spiral phase plate (SPP2). In some examples, the topological charge of the first spiral phase plate (SPP1) can be of order +1, and the topological charge of the second spiral phase plate (SPP2) can be of order -1.
[0086] Step S222: Combine the first Gaussian Laguerre beam and the second Gaussian Laguerre beam to obtain the target beam.
[0087] In this embodiment, the first Gaussian Laguerre beam and the second Gaussian Laguerre beam obtained in step S221 can be input into a polarization beam combiner (PBC) for beam combining to obtain the target beam. In some examples, the target beam can be... The beams of the four vector quality factors.
[0088] In the above design, since the bandwidth of the analog-to-digital converter (DAC) and the electro-optic modulation component 110 is large, which can be tens of GHz, and the first spiral phase plate (SPP1) and the second spiral phase plate (SPP2) are both passive optical devices, the frequency of the generated target beam is also large, which can be tens of GHz. In this way, the bandwidth of free space optical communication can be improved, thereby realizing high-speed communication.
[0089] In one possible implementation, please refer to Figure 7 Step S400 may include the following sub-steps.
[0090] In step S410, the receiving end 200 receives the target beam and performs beam splitting processing on the target beam to obtain a horizontally polarized beam, a vertically polarized beam, a diagonally polarized beam, and a right-hand circularly polarized beam.
[0091] Step S420: Electrical signals are acquired from the horizontally polarized beam, the vertically polarized beam, the diagonally polarized beam, and the right-hand circularly polarized beam to obtain the measured values of horizontal polarization power, vertical polarization power, diagonal polarization power, and right-hand circularly polarized power.
[0092] Step S430: Determine the concurrency of the target beam based on the measured values of the horizontal polarization power, the vertical polarization power, the diagonal polarization power, and the right-hand circular polarization power.
[0093] The relationship between the Stokes parameters of the light field and the two orthogonal modes is as follows:
[0094] in, , , , It can represent local Stokes parameters. , It can represent a pair of orthogonal spatial patterns. , It can represent the optical field propagating in the far field after phase perturbation.
[0095] Based on the global Stokes parameter, the concurrency degree C can be simplified to the following expression:
[0096] in, , , , It can represent Stokes parameters. Local Stokes parameters can be projected through horizontal polarization intensity (I). H ), vertical polarization intensity projection (I V ), diagonal polarization intensity projection (I D ) and right-hand circularly polarized polarization intensity projection (I R The calculation yielded:
[0097] Therefore, the concurrency level C can be calculated in the following way:
[0098] in, P i P can represent the polarization projection power after transverse integration. V P H P D P R These represent the measured values of horizontal polarization power, vertical polarization power, diagonal polarization power, and right-hand circular polarization power, respectively.
[0099] Please refer to Figure 8The receiver 200 may include an optical metasurface 210 (MS), a photodetector array chip 220 (PDA), and an analog-to-digital converter 230 (ADC). In step S410, when the target beam is transmitted to the receiver 200, it can be received by an optical antenna. The received target beam is then transmitted to the optical metasurface 210 (MS) via a second telescope (Tel.2). The optical metasurface 210 (MS) splits the target beam into four beams, and simultaneously modulates the phase and polarization distribution of the output light to obtain a horizontally polarized beam, a vertically polarized beam, a diagonally polarized beam, and a right-hand circularly polarized beam. In step S420, the horizontally polarized beam, vertically polarized beam, diagonally polarized beam, and right-hand circularly polarized beam can undergo photoelectric conversion by the photodetector array chip 220 (PDA), followed by electrical signal acquisition by the analog-to-digital converter 230 (ADC) to obtain the corresponding horizontal polarization power measurement values, vertical polarization power measurement values, diagonal polarization power measurement values, and right-hand circularly polarized beam measurement values, respectively. In step S430, a digital signal processing algorithm can calculate the concurrency degree corresponding to the target beam based on the horizontal polarization power measurement values, vertical polarization power measurement values, diagonal polarization power measurement values, and right-hand circularly polarized beam measurement values obtained in step S420, and then decode the transmitted bits to determine the information carried by the target beam.
[0100] In the above design, the vector quality factor (VQF) of the target beam is obtained according to the Stokes parameter, instead of the light intensity or phase wavefront detection in the prior art, thereby enabling information transmission based on vector light field vector quality factor (VQF) modulation.
[0101] In one possible implementation, please refer to Figure 9 Step S200 may also include the following sub-steps.
[0102] Step S223: Combine the modulated first polarized light signal and the second polarized light signal to obtain an initial combined beam.
[0103] Step S224: Adjust the polarization and spatial coupling strength of the initial beam combiner to encode information into the initial beam combiner to obtain a target beam carrying information.
[0104] In this embodiment, after combining the modulated first polarized light signal and the second polarized light signal using a polarization beam combiner (PBC) to obtain an initial beam, the coupling strength 'a' between the polarization of the initial beam and the spatial mode can be adjusted. The beam's vector dimension is used as the encoding reference for information encoding, thereby obtaining the target beam carrying information. Specifically, by changing the coupling strength 'a' between the polarization of the initial beam and the spatial mode, the beam's vector dimension can be controlled, thereby changing the transmitted information.
[0105] Based on the same inventive concept, this embodiment also provides an electronic device 700, please refer to... Figure 10 , Figure 10 A block diagram of an example electronic device 700. Electronic device 700 includes a free-space optical communication device 730, a computer-readable storage medium 720, and a processor 710.
[0106] The computer-readable storage medium 720 and the processor 710 are electrically connected directly or indirectly to enable data transmission or interaction. For example, these components can be electrically connected to each other via one or more communication buses or signal lines. The free-space optical communication device 730 includes multiple software functional modules that can be stored as software or firmware in the computer-readable storage medium 720 or embedded in the operating system (OS) of the free-space optical communication device 730. The processor 710 is used to execute executable modules stored in the computer-readable storage medium 720, such as the software functional modules and computer programs included in the free-space optical communication device 730.
[0107] The computer-readable storage medium 720 may be, but is not limited to, random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc. The computer-readable storage medium 720 is used to store a program, which the processor 710 executes after receiving an execution instruction.
[0108] The processor 710 may be an integrated circuit chip with signal processing capabilities. The aforementioned processor 710 can be a general-purpose processor 710, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor 710 can be a microprocessor 710, or any conventional processor 710, etc.
[0109] Please refer to Figure 11 This application also provides a free-space optical communication device 730. The free-space optical communication device 730 includes multiple functional modules that can be stored in software form in a computer-readable storage medium 720. Functionally, the free-space optical communication device 730 may include a beam splitting module 731, a modulation module 732, a transmission module 733, and a determination module 734. Wherein: The beam splitting module 731 can be used to acquire an initial optical signal and perform beam splitting processing on the initial optical signal to obtain a first polarized optical signal and a second polarized optical signal, wherein the polarization states of the first polarized optical signal and the second polarized optical signal are mutually orthogonal.
[0110] In this embodiment, the beam splitting module 731 can be used to perform... Figure 2 For a detailed description of the beam splitting module 731, please refer to the description of step S100 shown in step S100.
[0111] The modulation module 732 can be used to modulate the first polarized light signal and the second polarized light signal, and to combine the modulated first polarized light signal and the second polarized light signal to obtain the target beam.
[0112] In this embodiment, the modulation module 732 can be used to perform... Figure 2 For a detailed description of the modulation module 732, please refer to the description of step S200 shown in step S200.
[0113] The transmitting module 733 can be used to transmit the target beam to the receiving end 200 via the free space channel 300.
[0114] In this embodiment, the sending module 733 can be used to perform... Figure 2 For a detailed description of the sending module 733, please refer to the description of step S300 shown.
[0115] The determining module 734 can be used to receive the target beam and determine the concurrency degree corresponding to the target beam, wherein the concurrency degree is used to determine the information carried by the target beam.
[0116] In this embodiment, the determination module 734 can be used to perform... Figure 2 For a detailed description of the determination module 734, please refer to the description of step S400 shown.
[0117] In summary, the embodiments of this application provide a free-space optical communication method, apparatus, and electronic device. By performing beam splitting processing on the initial optical signal and modulating the first polarized optical signal and the second polarized optical signal after beam splitting processing, the vector nature of the light beam can be dynamically adjusted, and the anti-turbulence transmission capability of the free-space optical communication system can be improved.
[0118] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0119] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A free-space optical communication method, characterized in that, An application is made in a free-space optical communication system, the free-space optical communication system comprising a transmitter, a receiver, and a free-space channel, wherein the transmitter and the receiver are connected through the free-space channel; the transmitter includes an electro-optic modulation component; The method includes: The transmitting end acquires an initial optical signal and performs beam splitting processing on the initial optical signal to obtain a first polarized optical signal and a second polarized optical signal, wherein the polarization states of the first polarized optical signal and the second polarized optical signal are mutually orthogonal. The first polarized light signal and the second polarized light signal are modulated by the electro-optic modulation component of the transmitting end, and the modulated first polarized light signal and the second polarized light signal are combined to obtain the target beam. The transmitting end transmits the target beam to the receiving end through a free-space channel; The receiving end receives the target beam and determines the concurrency level corresponding to the target beam, wherein the concurrency level is used to determine the information carried by the target beam.
2. The free-space optical communication method according to claim 1, characterized in that, The electro-optic modulation component includes a first modulation branch and a second modulation branch; The step of modulating the first polarized light signal and the second polarized light signal using the electro-optic modulation component at the transmitting end includes: A first radio frequency voltage signal and a second radio frequency voltage signal are respectively applied to the first modulation branch and the second modulation branch of the electro-optic modulation component, wherein the first radio frequency voltage signal and the second radio frequency voltage signal are pulse amplitude modulation signals with different level intervals; The first polarized light signal is modulated through the first modulation branch, and the second polarized light signal is modulated through the second modulation branch.
3. The free-space optical communication method according to claim 2, characterized in that, The first radio frequency voltage signal V H Obtained through the following methods: The second radio frequency voltage signal V V Obtained through the following methods: in, , , t H The intensity transfer function represents the light intensity of the first polarized light signal; t V The intensity transfer function represents the light intensity of the second polarized light signal. , C represents concurrency; V π Indicates half-wave voltage; This represents the static residual phase difference between the two arms. This indicates the bias voltage.
4. The free-space optical communication method according to claim 1, characterized in that, The transmitting end also includes a first spiral phase plate and a second spiral phase plate; The step of combining the modulated first polarized light signal and the second polarized light signal to obtain the target beam includes: The modulated first polarized light signal is converted into a first Gaussian Laguerre beam through the first spiral phase plate; and the modulated second polarized light signal is converted into a second Gaussian Laguerre beam through the second spiral phase plate, wherein the topological charge of the first spiral phase plate is opposite to that of the second spiral phase plate. The first Gaussian Laguerre beam and the second Gaussian Laguerre beam are combined to obtain the target beam.
5. The free-space optical communication method according to claim 1, characterized in that, The step of receiving the target beam and determining the concurrency of the target beam includes: The receiving end receives the target beam and performs beam splitting on the target beam to obtain a horizontally polarized beam, a vertically polarized beam, a diagonally polarized beam, and a right-hand circularly polarized beam. Electrical signals were acquired from the horizontally polarized beam, the vertically polarized beam, the diagonally polarized beam, and the right-hand circularly polarized beam to obtain the measured values of horizontal polarization power, vertical polarization power, diagonal polarization power, and right-hand circular polarization power. The concurrency of the target beam is determined based on the measured values of horizontal polarization power, vertical polarization power, diagonal polarization power, and right-hand circular polarization power.
6. The free-space optical communication method according to claim 5, characterized in that, The concurrency level corresponding to the target beam is obtained in the following way: Among them, P V P H P D P R These represent the horizontal polarization power measurement value, the vertical polarization power measurement value, the diagonal polarization power measurement value, and the right-hand circular polarization power, respectively.
7. The free-space optical communication method according to claim 1, characterized in that, The step of combining the modulated first polarized light signal and the second polarized light signal to obtain the target beam includes: The modulated first polarized light signal and the second polarized light signal are combined to obtain an initial combined beam. By adjusting the coupling strength between the polarization and spatial mode of the initial combined beam, information encoding is performed on the initial combined beam to obtain a target beam carrying information.
8. A free-space optical communication device, characterized in that, An application is made in a free-space optical communication system, the free-space optical communication system comprising a transmitter, a receiver, and a free-space channel, wherein the transmitter and the receiver are connected through the free-space channel; the transmitter includes an electro-optic modulation component; The free-space optical communication device includes: A beam splitting module is used to acquire an initial optical signal and perform beam splitting processing on the initial optical signal to obtain a first polarized optical signal and a second polarized optical signal, wherein the polarization states of the first polarized optical signal and the second polarized optical signal are mutually orthogonal. The modulation module is used to modulate the first polarized light signal and the second polarized light signal, and to combine the modulated first polarized light signal and the second polarized light signal to obtain the target beam. A transmitting module is used to transmit the target beam to a receiving end via a free-space channel; A determining module is used to receive the target beam and determine the concurrency degree corresponding to the target beam, wherein the concurrency degree is used to determine the information carried by the target beam.
9. An electronic device, characterized in that, include: Memory, used to store one or more programs; A processor, when the one or more programs are executed by the processor, implements the method as described in any one of claims 1-7.
10. A computer-readable storage medium, characterized in that, It stores a computer program, characterized in that, when the computer program is executed by a processor, it implements the method as described in any one of claims 1-7.