A novel synthetic dimension optoelectronic oscillator device and implementation method for arbitrary chirp signal generation

Abstract

This invention belongs to the field of optoelectronic technology, specifically relating to a novel synthetic dimension optoelectronic oscillator device and its implementation method for generating arbitrary chirped signals. This invention utilizes a high-speed phase modulation unit based on lithium niobate technology as the core component. By adjusting the delay difference between the phase drive signal period and the optoelectronic oscillator, it achieves a deep fusion of optical dimension synthesis and electronic feedback oscillation, enabling the generation of microwave signals with arbitrarily adjustable instantaneous frequencies. Furthermore, by controlling the time mismatch and drive signal voltage, the bandwidth and repetition rate of the output signal can be flexibly tuned. This invention combines the advantages of photonic bandwidth and flexibility with the stability and precision of electronics, enabling the generation of broadband, highly stable complex waveforms, and is expected to meet the application requirements of next-generation intelligent sensing systems for high-resolution detection and flexible waveform generation.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, specifically to a novel synthetic dimension optoelectronic oscillator device and its implementation method for generating arbitrary chirped signals. Background Technology

[0002] Chirped signals are waveforms whose frequency varies controllably over time. Through frequency spreading techniques, they can effectively improve the range resolution and anti-interference capabilities of a system, and have become a fundamental waveform for key technologies such as high-resolution lidar and long-distance communication. However, with increasingly complex electromagnetic environments and ever-increasing sensing demands, higher requirements are being placed on waveform freedom and performance. Currently, traditional chirped signal generation mainly relies on electronic methods such as direct digital synthesizers (DDS) or voltage-controlled oscillators (VCOs). These methods are limited by the finite sampling rate and inherent nonlinearity of electronic devices. When generating high-frequency, broadband, and nonlinear chirps, complex frequency harmonics and mixer cascades are often required, resulting in bloated system structures, low energy efficiency, and severely limited real-time reconstruction capabilities. These limitations at the electronic level have become a key bottleneck restricting the achievement of higher performance and more flexible waveform synthesis in next-generation intelligent sensing and communication systems.

[0003] Against this backdrop, novel waveform generation techniques based on synthetic dimensions offer a fresh approach to overcoming the aforementioned electronic bottlenecks (Guan, Y. et al. Temporal point-by-point arbitrary waveform synthesis beyond tera sample per second. Nat. Commun. 16, 2798 (2025)). Synthetic dimension is an emerging physical paradigm whose core lies in constructing virtual dimensions using the internal degrees of freedom of a physical system, thereby enabling high-dimensional signal processing and complex waveform synthesis on low-dimensional hardware platforms. Among various implementation schemes, photonic synthesis of frequency dimensions based on dynamic modulation has attracted much attention due to its excellent controllability and scalability (Yuan, L., Lin, Q., Xiao, M. & Fan, S. Synthetic dimension in photonics. Optica 5, 1396–1405 (2018)). This technique can construct artificial lattices in the frequency domain by precisely controlling discrete spectral modes in optical resonators or loops, and then indirectly synthesize the desired time-domain waveforms via Fourier transform relationships. However, the potential of this technology has not yet been fully realized in the field of microwave signal generation. On the one hand, existing research is mostly focused on theoretical simulation and principle verification, and has not yet developed an efficient and stable system architecture for practical application. On the other hand, the inherent photon shot noise and sensitivity to environmental disturbances in pure photonic systems can lead to a significant increase in the noise floor of the generated signal and a deterioration in long-term stability, making it difficult to meet the stringent requirements for signal coherence and spectral purity in applications such as radar detection and precision sensing.

[0004] In summary, traditional electronic methods face physical bottlenecks in generating high-frequency broadband chirped signals due to bandwidth and nonlinearity. While emerging photonic synthesis technology has great potential, it is currently constrained by the lack of efficient and practical architectures and inherent defects such as high photonic noise and poor environmental robustness, making it difficult to meet the stringent requirements of high-performance radar and communication for signal coherence and long-term stability. Summary of the Invention

[0005] To overcome the aforementioned challenges, this invention proposes an innovative optoelectronic collaborative architecture that deeply integrates the optical synthesis frequency dimension with the electronic feedback oscillation mechanism. Utilizing a high-speed phase modulation unit to program a reconfigurable frequency-domain lattice within the optoelectronic loop, it directly synthesizes microwave signals with arbitrary instantaneous frequency characteristics. Results show that this system not only achieves the generation of broadband arbitrary chirped signals but also possesses excellent long-term stability, meeting the stringent requirements of high-precision sensing and detection for signal consistency. Therefore, this invention provides a practical technical path to solve the current bottleneck problem in electronic waveform generation and lays an important hardware foundation for the development of next-generation intelligent sensing and communication systems.

[0006] The technical solution of the present invention is as follows: a novel synthetic dimension optoelectronic oscillator device and implementation method for generating arbitrary chirped signals. The device includes: a laser (1), a dual parallel Mach-Zehnder electro-optic modulator (2), a dual-port DC source (3), a low-speed arbitrary waveform generator (4), a tunable optical filter (5), an erbium-doped fiber amplifier (6), a single-mode fiber (7), a photodetector (8), an electrical amplifier (9), an electrical filter (10), and a power divider (11). The device is characterized by the following connection order: the output end of the laser (1) is connected to the optical input end of the dual parallel Mach-Zehnder electro-optic modulator (2). The DC bias ports of the upper and lower sub-arms of the dual parallel Mach-Zehnder electro-optic modulator (2) are respectively connected to the two voltage output ends of the dual-port DC source (3), and the DC bias port of the main arm of the dual parallel Mach-Zehnder electro-optic modulator (2) is connected to the output end of the low-speed arbitrary waveform generator (4). The optical output of the dual parallel Mach-Zehnder electro-optic modulator (2) is connected to the input of the tunable optical filter (5). The output of the tunable optical filter (5) is connected to the input of the erbium-doped fiber amplifier (6). The output of the erbium-doped fiber amplifier (6) is connected to the input of the single-mode fiber (7). The output of the single-mode fiber (7) is connected to the optical signal input of the photodetector (8). The electrical signal output of the photodetector (8) is connected to the input of the electrical amplifier (9). The output of the electrical amplifier (9) is connected to the input of the electrical filter (10). The output of the electrical filter (10) is connected to the input of the power divider (11). One output of the power divider (11) is connected to the RF signal input port of the lower arm of the dual parallel Mach-Zehnder electro-optic modulator (2), and the other output is the chirp signal output of the photoelectric oscillator.

[0007] The method for implementing the novel synthetic-dimensional optoelectronic oscillator for generating arbitrary chirped signals includes the following steps: Step 1: The optical signal output from the laser (1) is transmitted through the dual parallel Mach-Zehnder electro-optic modulator (2), which is driven by a chirped custom signal generated by the self-excited oscillation of the photoelectric oscillator. The DC bias points of the upper and lower sub-arms in the dual parallel Mach-Zehnder electro-optic modulator (2) are adjusted using a dual-port DC source (3) so that they operate at the maximum transmission point and the minimum transmission point, respectively. The voltage signal output from the low-speed arbitrary waveform generator (4) is applied to the DC bias port of the main arm of the dual parallel Mach-Zehnder electro-optic modulator (2), which can arbitrarily adjust the phase difference between the optical carrier and the first-order sideband. Step 2: Inject the modulated optical signal, which includes the carrier and multiple sidebands, output from the dual parallel Mach-Zehnder electro-optic modulator (2) into the tunable optical filter (5). By finely adjusting the center wavelength and operating bandwidth of the tunable optical filter (5), its transmission spectrum is aligned with specific optical wave components, filtering out the negative first-order sidebands in the modulation spectrum, while completely preserving the optical carrier and positive first-order sidebands; Step 3: Inject the filtered optical signal into the erbium-doped fiber amplifier (6). By adjusting the pump power of the erbium-doped fiber amplifier (6), the power of the optical signal is increased so that it can fully compensate for the insertion loss in the optical link and ensure that the open-loop gain of the protection system meets the oscillation condition. Subsequently, the power-compensated optical signal is input into a single-mode fiber (7) of a predetermined length for transmission to introduce the required time delay. Finally, the optical signal enters the photodetector (8) for square-law detection, demodulating the information carried by the optical carrier and a section of optical sideband into a radio frequency current signal with controllable phase-frequency characteristics. Step 4: The RF signal output by the photodetector (8) is first connected to the amplifier (9) for gain compensation to offset the electrical transmission loss in the loop; then the signal passes through the filter (10) to filter out out-of-band noise and select a specific operating frequency band. The processed signal enters the power divider (11) and is divided into two paths: the first path serves as a feedback signal, which is sent back to the RF input port of the lower arm of the dual parallel Mach-Zehnder electro-optic modulator (2), thereby closing the photoelectric feedback loop, so that the system meets the oscillation conditions and maintains stable photoelectric oscillation; the second path serves as the system output, generating a chirped microwave signal. Step 5: A dual-parallel Mach-Zehnder electro-optic modulator (2) and a tunable optical filter (5) are cascaded to form a microwave photonic phase-shifting unit. In this unit, the DC bias voltage of the main arm of the dual-parallel Mach-Zehnder electro-optic modulator (2) is used as a control variable. By changing the bias point, a tunable phase shift can be introduced into the signal within the loop over an extremely wide frequency band (covering tens of GHz). This step utilizes the large bandwidth characteristics of photonics technology to break through the bandwidth bottleneck of traditional electronic phase shifters, providing a foundation for generating broadband chirped signals. Step 6 Figure 2The diagram shows the schematic of the proposed device. The time variable between the phase drive signal period and the loop delay is set to dt. Relying on the feedback mechanism of the photoelectric oscillator, the system can accumulate the time-domain waveform of the drive signal and convert it into the phase information of the oscillation signal, thus achieving the numerical integration effect of phase with respect to the drive signal. At this point, the time-domain expression of the loop output signal is expressed as: Phase ( T )=2 πf 0 T + φ 0+ πV π · dt ·∫ S ( t ) dt Further analysis of its instantaneous frequency characteristics reveals that the frequency modulation trajectory of the output signal remains consistent with the waveform of the phase drive signal. f ( T )= f 0+ S ( t ) / (2 V π · dt Meanwhile, the frequency sweep range of the signal (determined by the high and low cutoff frequencies) is mainly determined by the magnitude of the time mismatch and the modulation depth of the driving signal. By adjusting the above parameters, the signal bandwidth can be flexibly reconstructed.

[0008] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: (1) This invention overcomes the bandwidth and nonlinearity bottlenecks of traditional electronic methods, achieving high-speed and flexible arbitrary chirped waveform synthesis. By introducing a synthesis frequency dimension into the optoelectronic oscillator and utilizing high-speed phase modulation to map the fine control of the optical frequency domain lattice to the electrical domain, this invention overcomes the physical limitations of traditional electronic devices in terms of sampling rate and nonlinearity. This enables the system to quickly generate complex chirped signals with arbitrary instantaneous frequencies, achieving a frequency tuning rate of up to 1238.1 THz / s, greatly improving the waveform reconstruction capability and bandwidth flexibility. (2) This invention solves the problem of poor environmental stability in pure photonic systems, ensuring high precision and long-term stability of signal generation. Unlike pure photonic generation schemes, which are easily affected by environmental disturbances and photon shot noise, this invention adopts a photoelectric feedback oscillation architecture and provides a high-precision frequency stabilization mechanism using an electronic feedback loop. Experiments show that the root mean square amplitude fluctuation of the system is extremely small (<0.02 V) during a two-hour stability test, effectively overcoming the inherent defects of high noise and poor stability in photonic methods, and meeting the requirements of engineering applications for long-term signal source stability. (3) The system architecture is streamlined and compact, effectively reducing the complexity and cost of hardware implementation. Compared with traditional electronic methods, this invention is based on the synthesis frequency dimension theory, which enables the generation of high-dimensional signals on a low-dimensional general optoelectronic hardware platform. This architecture avoids dependence on extreme performance electronic devices, significantly simplifies the system structure, and reduces hardware costs and energy consumption, while also facilitating system integration and practical deployment. Attached Figure Description

[0009] Figure 1 This invention provides a novel synthetic dimension optoelectronic oscillator device for generating arbitrary chirped signals; Figure 2 This is a schematic diagram illustrating the working principle of a novel synthetic dimension optoelectronic oscillator device for generating arbitrary chirped signals according to the present invention. (a) High-speed phase modulation unit, (b) Frequency dimension synthesis scheme based on time parameter mismatch; Figure 3 Phase frequency response characteristics of the phase modulation unit. (a) Phase shift test results of 5 GHz microwave signal; (b) Relationship curves between phase shift and driving voltage at different center frequencies (2.5 GHz, 5.0 GHz, 7.5 GHz and 10.0 GHz); Figure 4 The system output characteristics are shown when the phase drive signal is set to a sinusoidal signal. (a) Time-frequency characteristics of the output signal, (b) Time-domain waveform of the output signal, (c) Frequency-domain characteristics of the output signal; Figure 5 The effects of drive signal voltage (a) and time mismatch (b) on output signal bandwidth; Figure 6 The time-frequency analysis results of the system output signal are obtained when the phase driving signal is set to a triangular wave (a) and a third-order Gaussian pulse (b), respectively. Among them, 1 is a laser, 2 is a dual parallel Mach-Zehnder electro-optic modulator, 3 is a dual-port DC source, 4 is a low-speed arbitrary waveform generator, 5 is a tunable optical filter, 6 is an erbium-doped fiber amplifier, 7 is a single-mode fiber, 8 is a photodetector, 9 is an electrical amplifier, 10 is an electrical filter, and 11 is a power divider. Detailed Implementation

[0010] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0011] Combination Figure 1 and Figure 2The system principle of this invention is further explained as follows: like Figure 1 As shown, the continuous optical carrier signal output from the light source is injected into a dual parallel Mach-Zehnder electro-optic modulator. Internally, the modulator splits the optical signal into two paths via an input Y-branch waveguide: the first path enters the upper arm sub-modulator, which is controlled by DC bias to operate at its maximum transmission point, outputting a high-power optical carrier; the second path enters the lower arm sub-modulator, which is controlled to operate at its minimum transmission point, generating a carrier-suppressed optical sideband signal. A voltage signal output from a low-speed arbitrary waveform generator is applied to the main bias port of the dual parallel Mach-Zehnder electro-optic modulator. By adjusting the phase bias of the main modulator, a controllable additional phase difference is introduced between the optical carrier signal and the first-order optical sideband signal. Furthermore, the parameters of the low-speed arbitrary waveform generator are configured to maintain a preset small time mismatch between the period of its output signal and the loop delay of the photoelectric oscillator. Subsequently, the two optical signals are combined via the output Y-branch waveguide and injected into a tunable optical filter. By adjusting the passband range of the filter, the negative first-order optical sideband in the combined signal is filtered out. The filtered optical signal is sequentially passed through an erbium-doped fiber amplifier for gain compensation and a single-mode fiber for loop delay before being converted into an electrical signal by a photodetector. This electrical signal is amplified by an electrical amplifier and filtered for noise by an electrical bandpass filter before being input to a power divider and split into two paths: one path is fed back to the RF input port of the lower arm of a dual parallel Mach-Zehnder electro-optic modulator, thus closing the photoelectric feedback oscillation loop; the other path serves as the system output port, outputting an arbitrary chirped waveform.

[0012] like Figure 2 As shown in (a), the laser, the dual-parallel Mach-Zehnder electro-optic modulator, and the tunable optical filter together constitute the phase modulation unit of this invention. Theoretically, the output signal of the dual-parallel Mach-Zehnder electro-optic modulator can be expressed as...

[0013] in E in ( t )and J 1(·) represents the optical carrier signal and the positive first-order Bessel function, respectively. m , f 0 and φ 0 corresponds to the modulation depth, frequency, and initial phase of the feedback signal. In addition, S ( t The signal is the phase drive signal generated by a low-speed arbitrary waveform generator. V π This represents the DC half-wave voltage of the main arm of the dual-parallel Mach-Zehnder electro-optic modulator. The modulated optical signal generated by the dual-parallel Mach-Zehnder electro-optic modulator, after filtering by a tunable optical filter and conversion by a photodetector, produces a current signal that can be expressed as...

[0014] in α , R and P 0 represents the responsivity, matching impedance, and incident light power of the photodetector, respectively. Analysis of the above equation shows that the instantaneous phase of the photodetector's output signal is related to the externally applied driving electrical signal. S ( t There is a clear mapping relationship between them. This indicates that by using this driving signal as a modulation source, a time-varying phase shift can be directly and efficiently introduced into the microwave signal after photoelectric detection, thereby achieving high-speed, full-range, continuously adjustable phase control, which provides the necessary conditions for subsequent waveform synthesis.

[0015] Figure 2 (b) illustrates the principle of the dimensional synthesis scheme based on time parameter mismatch. The period of the phase driving signal S(t) is set. T s With loop delay τ The time mismatch between them is dt At this time, the loop output signal satisfies

[0016] in t 0 represents the relative time parameter in the loop, with a value ranging from 0 to... τ . n Represents a positive integer. Considering that the phase drive signal is a periodic signal, the loop output signal satisfies...

[0017] in T = t 0+ n·τ The discrete sampling points representing the time axis quantify the evolution of the dynamic process within the photoelectric oscillator. Ultimately, the instantaneous frequency of the photoelectric oscillator's output signal satisfies...

[0018] Based on the theoretical model described by formula (5), it can be seen that the instantaneous frequency shape (i.e., chirp profile) of the system output signal is related to the externally applied phase drive signal. S ( t A one-to-one linear mapping relationship is established between the time-domain waveforms of the signal. This characteristic indicates that the present invention can drive the signal through flexible programming. S ( tThe waveform shape directly and precisely controls the frequency evolution of the output signal over time, thus enabling the synthesis of arbitrary chirped waveforms. Furthermore, this formula quantitatively reveals the regulation mechanism of the system's generated signal bandwidth: the signal bandwidth is determined by the time mismatch within the loop. dt It is determined together with the voltage amplitude of the drive signal. Specifically, it is determined by the bandwidth and time mismatch. dt It is inversely proportional to the driving signal. S ( t The voltage amplitude is directly proportional to the time mismatch. This means that in practical applications, the time mismatch can be controlled by adjusting the voltage amplitude. dt Setting the value to a minimum or appropriately increasing the voltage amplitude of the driving signal can significantly expand the spectral coverage of the output signal, thereby enabling the efficient generation of high-frequency, wide-bandwidth signals.

[0019] The feasibility of the present invention will be explained below with reference to specific embodiments: Example 1:

[0020] according to Figure 1 The structure shown demonstrates the generation of arbitrary chirped signals based on a novel optoelectronic oscillator using a synthesis dimension technique. In the experimental system, the light source is a distributed feedback laser with a center wavelength of 1550.02 nm and an output power of 19.1 dBm. The dual parallel Mach-Zehnder electro-optic modulator has a working bandwidth of approximately 15 GHz, and the tunable optical filter has a center wavelength of approximately 1549.98 nm and a 3 dB bandwidth of approximately 0.08 nm. The photodetector has a simulated bandwidth of approximately 40 GHz, the electrical amplifier operates in the DC-40 GHz frequency range with a gain of approximately 40 dB, and the electrical filter has a center frequency of 5 GHz and a 3 dB bandwidth of 2 GHz. In the experiment, vector network analysis was used to test the frequency response characteristics of the microwave photonic phase-shifting unit constructed in this invention, with an operating frequency band of 10MHz-50GHz; a high-speed oscilloscope was used to test the time-domain characteristics of the chirped output signal of this invention, with a sampling rate of 100Gsa / s and an analog bandwidth of 33GHz; a spectrum analyzer was used to test the frequency-domain characteristics of the chirped output signal of this invention, with an operating frequency band of 2Hz-85GHz.

[0021] In the experiment, the photoelectric oscillator was disconnected, and port 2 of the vector network analyzer was connected to the RF input port of the lower arm of the dual parallel Mach-Zehnder electro-optic modulator, while port 1 was connected to the output port of the photodetector. The phase frequency response of the phase modulation unit was tested. The DC bias voltage of the upper arm of the dual parallel Mach-Zehnder electro-optic modulator was set to 1.73V, and the DC bias voltage of the lower arm was set to 9.84V, so that the two sub-modulators operated at the maximum and minimum transmission points, respectively. A low-speed arbitrary waveform generator was used to output a DC voltage signal to control the DC bias port of the main arm of the dual parallel Mach-Zehnder electro-optic modulator. Figure 3As shown in (a), a microwave signal with a center frequency of 5 GHz was selected as the test signal, and the frequency span of the vector network analyzer was set to 50 Hz. By adjusting the DC bias voltage applied to the phase adjustment unit, the test results show that the phase of the microwave signal can be continuously adjusted within the range of -180° to +180°, indicating that the unit has the ability to perform a phase shift of a complete cycle. Figure 3 As shown in (b), to verify the broadband response characteristics and linearity of the phase modulation unit, microwave signals with center frequencies of 2.5 GHz, 5.0 GHz, 7.5 GHz, and 10.0 GHz were selected for testing. The horizontal axis in the figure represents the applied driving voltage, and the vertical axis represents the phase change. As can be seen from the figure, at the above four frequency points, the phase change and the driving voltage exhibit a good linear positive correlation. This result indicates that the phase modulation unit of the present invention has excellent linear modulation characteristics over a wide frequency range, which is beneficial for subsequent precise control of the microwave signal phase.

[0022] By closing the photoelectric oscillator and setting the phase drive signal to a sine wave with a peak-to-peak value of 10.2V (time mismatch approximately 921ps), this system successfully synthesized the following: Figure 4 The sinusoidal chirped signal shown is noteworthy. It is worth mentioning that, thanks to the time-phase mapping control mechanism employed in this invention, the generated chirped signal exhibits extremely high envelope flatness in the time domain, with almost no observable amplitude fluctuations. Furthermore, combined with… Figure 4 The spectrum and time-frequency analysis results show that the signal has a flat power spectral density and a 3dB bandwidth of 1.3GHz. The instantaneous frequency evolution trajectory of the signal accurately reproduces the waveform characteristics of the sinusoidal driving signal, and the signal repetition period is measured to be approximately 216.22ns.

[0023] Example 2: This embodiment is based on Embodiment 1 and adopts the same... Figure 1 The system architecture and core optoelectronic devices shown are the same, and a sine wave is also used as the phase drive signal. The difference in this embodiment is that, by using numerical simulation, the amplitude of the drive signal and the time mismatch within the system are systematically changed to quantitatively verify the regulation law of these two key parameters on the output signal bandwidth. In the numerical simulation, the system sampling rate is set to 100 GSa / s, the loop delay is set to 1 μs, the DC half-wave voltage of the main arm of the dual parallel Mach-Zehnder electro-optic modulator is set to 18V, and the overall net gain of the system is set to 1.001.

[0024] First, the controllability characteristics of the output signal bandwidth were analyzed. For example... Figure 5As shown in (a), the simulation results reveal a significant positive linear correlation between the signal bandwidth and the amplitude of the driving signal: as the amplitude of the driving signal gradually increases from 10V to 30V, the generated signal bandwidth correspondingly expands from approximately 1.9GHz to approximately 5.4GHz. This result indicates that, within the system's allowable range, increasing the amplitude of the driving signal is an effective means of improving the output signal bandwidth and exhibits good linear control characteristics. Figure 5 As shown in (b), the curve reflects the dependence of signal bandwidth on time mismatch. The figure reveals a significant negative correlation: as the time mismatch increases from 0.5 ns to 0.9 ns, the signal bandwidth exhibits a rapid decay (decreasing from approximately 4.0 GHz to near 0 GHz). This indicates that the system's time mismatch plays a crucial limiting role in the bandwidth of the generated signal; by precisely controlling and minimizing the time mismatch, the system's output bandwidth performance can be significantly improved.

[0025] Secondly, to further verify the reconfigurability and waveform generation flexibility of the device described in this invention, this embodiment continues to use numerical simulation methods, selecting complex non-sinusoidal waveforms for testing. For example... Figure 6 As shown, when the phase drive signal is configured as a linear function waveform and a third-order Gaussian pulse function waveform, respectively, the instantaneous frequency evolution trajectory of the system output signal can reproduce the time characteristics of the drive signal with high fidelity. Figure 6 The image above shows a clear outline of periodic linear frequency modulation. Figure 6 The figure below shows a clear profile of a third-order Gaussian pulse. This simulation result fully verifies the ability of the device of this invention to generate various complex waveforms and its excellent versatility.

[0026] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A novel synthetic-dimensional photoelectric oscillator device for generating arbitrary chirped signals, characterized in that: Includes a laser (1), a dual parallel Mach-Zehnder electro-optic modulator (2), a dual-port DC source (3), a low-speed arbitrary waveform generator (4), a tunable optical filter (5), an erbium-doped fiber amplifier (6), a single-mode fiber (7), a photodetector (8), an electrical amplifier (9), an electrical filter (10), and a power divider (11). The components are connected in the following order: the output of the laser (1) is connected to the optical input of the dual parallel Mach-Zehnder electro-optic modulator (2). The DC bias ports of the upper and lower sub-arms of the dual parallel Mach-Zehnder electro-optic modulator (2) are connected to the two voltage outputs of the dual-port DC source (3), respectively. The DC bias port of the main arm of the dual parallel Mach-Zehnder electro-optic modulator (2) is connected to the output of the low-speed arbitrary waveform generator (4). The optical output of the dual parallel Mach-Zehnder electro-optic modulator (2) is connected to the input of the tunable optical filter (5). The output of the tunable optical filter (5) is connected to the input of the erbium-doped fiber amplifier (6). The output of the erbium-doped fiber amplifier (6) is connected to the input of the single-mode fiber (7). The output of the single-mode fiber (7) is connected to the optical signal input of the photodetector (8). The electrical signal output terminal of the photodetector (8) is connected to the input terminal of the electrical amplifier (9), the output terminal of the electrical amplifier (9) is connected to the input terminal of the electrical filter (10), and the output terminal of the electrical filter (10) is connected to the input terminal of the power divider (11). One output terminal of the power divider (11) is connected to the radio frequency signal input port of the lower arm of the dual parallel Mach-Zehnder electro-optic modulator (2), and the other output terminal is the chirp signal output terminal of the photoelectric oscillator.

2. The novel synthetic-dimensional photoelectric oscillator device for generating arbitrary chirped signals according to claim 1, characterized in that, Includes the following steps: Step 1: The optical signal output from the laser (1) is transmitted through the dual parallel Mach-Zehnder electro-optic modulator (2), which is driven by a chirped custom signal generated by the self-excited oscillation of the photoelectric oscillator. The DC bias points of the upper and lower sub-arms in the dual parallel Mach-Zehnder electro-optic modulator (2) are adjusted using a dual-port DC source (3) so that they operate at the maximum transmission point and the minimum transmission point, respectively. The voltage signal output from the low-speed arbitrary waveform generator (4) is applied to the DC bias port of the main arm of the dual parallel Mach-Zehnder electro-optic modulator (2), which can arbitrarily adjust the phase difference between the optical carrier and the first-order sideband. Step 2: Inject the modulated optical signal, which includes the carrier and multiple sidebands, output from the dual parallel Mach-Zehnder electro-optic modulator (2) into the tunable optical filter (5). By finely adjusting the center wavelength and operating bandwidth of the tunable optical filter (5), its transmission spectrum is aligned with specific optical wave components, filtering out the negative first-order sidebands in the modulation spectrum, while completely preserving the optical carrier and positive first-order sidebands; Step 3: Inject the filtered optical signal into the erbium-doped fiber amplifier (6). By adjusting the pump power of the erbium-doped fiber amplifier (6), the power of the optical signal is increased so that it can fully compensate for the insertion loss in the optical link and ensure that the open-loop gain of the protection system meets the oscillation condition. Subsequently, the power-compensated optical signal is input into a single-mode fiber (7) of a predetermined length for transmission to introduce the required time delay. Finally, the optical signal enters the photodetector (8) for square-law detection, demodulating the information carried by the optical carrier and a section of optical sideband into a radio frequency current signal with controllable phase-frequency characteristics. Step 4: The RF signal output by the photodetector (8) is first connected to the amplifier (9) for gain compensation to offset the electrical transmission loss in the loop; then the signal passes through the filter (10) to filter out out-of-band noise and select a specific operating frequency band. The processed signal enters the power divider (11) and is divided into two paths: the first path serves as a feedback signal and is sent back to the RF input port of the lower arm of the dual parallel Mach-Zehnder electro-optic modulator (2), thereby closing the photoelectric feedback loop, so that the system meets the oscillation conditions and maintains stable photoelectric oscillation; The second path serves as the system output, generating a chirped microwave signal. Step 5: A dual-parallel Mach-Zehnder electro-optic modulator (2) and a tunable optical filter (5) are cascaded to form a microwave photonic phase-shifting unit. In this unit, the DC bias voltage of the main arm of the dual-parallel Mach-Zehnder electro-optic modulator (2) is used as a control variable. By changing the bias point, a tunable phase shift can be introduced into the signal within the loop over an extremely wide frequency band (covering tens of GHz). This step utilizes the large bandwidth characteristics of photonics technology to break through the bandwidth bottleneck of traditional electronic phase shifters, providing a foundation for generating broadband chirped signals. Step 6: Figure 2 shows the schematic diagram of the proposed device. The time variable between the phase drive signal period and the loop delay is set as follows: dt Relying on the feedback mechanism of the photoelectric oscillator, the system can accumulate the time-domain waveform of the driving signal and convert it into the phase information of the oscillation signal, thus achieving the numerical integration effect of phase with respect to the driving signal. At this point, the time-domain expression of the loop output signal is expressed as: Phase ( T )=2 πf 0 T + φ 0+ πV π · dt ·∫ S ( t ) dt Further analysis of its instantaneous frequency characteristics reveals that the frequency modulation trajectory of the output signal remains consistent with the waveform of the phase drive signal. f ( T )= f 0+ S ( t ) / (2 V π · dt Meanwhile, the frequency sweep range of the signal (determined by the high and low cutoff frequencies) is mainly determined by the magnitude of the time mismatch and the modulation depth of the driving signal. By adjusting the above parameters, the signal bandwidth can be flexibly reconstructed.

3. A novel synthetic dimension optoelectronic oscillator device and implementation method for generating arbitrary chirped signals as described in claim 2, characterized in that, The novel synthetic dimension optoelectronic oscillator device is the novel synthetic dimension optoelectronic oscillator device as described in claim 1.

4. A novel synthetic-dimensional photoelectric oscillator device and implementation method for generating arbitrary chirped signals as described in any one of claims 2-3, characterized in that, The novel synthetic dimension optoelectronic oscillator device for generating arbitrary chirped signals is the novel synthetic dimension optoelectronic oscillator device for generating arbitrary chirped signals as described in claim 1.

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