A method and system for simulating noise in a fiber optic link for optical frequency transfer

Abstract

The application relates to the technical field of optical fiber communication, in particular to an optical fiber optical frequency transmission field optical fiber link noise simulation method and system, which comprises the following steps: dividing laser generated by a laser into reference light and simulation light; after the simulation light is modulated and transmitted through a field optical fiber, the simulation light is subjected to optical frequency processing with the reference light to obtain a radio frequency signal; the radio frequency signal is subjected to phase processing to obtain continuous phase information and frequency conversion data; an optical fiber optical frequency transmission field optical fiber noise simulation model is constructed; the phase information and the frequency conversion data are converted into voltage data by using the noise simulation model; a modulation depth parameter is set according to the voltage data; modulation is carried out according to the modulation depth parameter; and the length of a laboratory winding optical fiber is adjusted according to a modulation result to realize noise simulation. The method can simulate field optical fiber link noises of different types and different magnitudes.

Description

Technical Field

[0001] This invention relates to the field of optical fiber communication technology, and specifically to a method and system for simulating noise in a real-world optical fiber link for optical frequency transmission. Background Technology

[0002] High-precision optical frequency transmission technology based on optical fibers is a crucial means to achieve stable long-distance transmission and comparison of high-precision optical clock standard frequency signals. However, due to different laying methods, real-world optical fibers exhibit varying types and magnitudes of additional phase noise, affecting the transmission stability of the optical frequency system. To more efficiently measure and evaluate the performance indicators of optical fiber frequency transmission systems, high-precision optical fiber frequency transmission test experiments are needed under different types and magnitudes of phase noise. However, the high cost of optical fiber resource leasing and the complex environment of communication equipment rooms make it difficult to conduct experimental tests, resulting in the inability to simulate different types and magnitudes of additional phase noise in real-world optical fibers. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and system for simulating noise in real-world optical fiber links, addressing the shortcomings of the prior art, and solving the technical problem of being unable to simulate different types and magnitudes of additional phase noise in real-world optical fibers.

[0004] The objective of this invention is achieved through the following technical solutions:

[0005] In a first aspect, the present invention provides a fiber optic frequency transmission field fiber optic link noise simulation system, which includes, in sequence along the signal propagation direction: a laser, a fiber optic coupler, an acousto-optic modulator, a photodetector, a signal processing module, and a fiber optic frequency transmission field fiber optic noise simulation module; the laser, fiber optic coupler, acousto-optic modulator, photodetector, and signal processing module are connected for communication via fiber optic links.

[0006] The laser is used to provide laser light, and the laser light is input to an optical fiber coupler to split the laser light generated by the laser into reference light and analog light;

[0007] The simulated light is modulated by an acousto-optic modulator, and the modulated simulated light is transmitted through a real optical fiber and then input to a photodetector with a reference light for optical frequency processing to obtain a radio frequency signal.

[0008] The radio frequency signal is input to the signal processing module for phase processing to obtain continuous phase information and frequency conversion data. The phase information and frequency conversion data are input to the fiber optic frequency transmission field fiber noise simulation module, which converts them into voltage data. First, the modulation depth parameter is set according to the voltage data, then modulation is performed according to the modulation depth parameter, and the fiber optic link length is adjusted according to the modulation result to achieve noise simulation.

[0009] As a further improvement of the present invention, it also includes a first Faraday rotator and a second Faraday rotator; the first Faraday rotator is disposed between the photodetector and the fiber coupler, and the Faraday rotator is used to reflect the reference light to the photodetector; the second Faraday rotator is communicatively connected to the acousto-optic modulator through a real optical fiber, and the second Faraday rotator is used to polarize and rotate the simulated light output from the real optical fiber at a set angle and reflect it to the photodetector.

[0010] As a further improvement of the present invention, a second acousto-optic modulator is also included, which is connected via a real optical fiber and a second Faraday rotator, and the driving frequency of the second acousto-optic modulator is a second set value; the second acousto-optic modulator is used to modulate the analog light output through the real optical fiber.

[0011] As a further improvement of the present invention, a signal conversion module is also included; the signal conversion module is disposed between the photodetector and the signal processing module; the signal conversion module includes a bandpass filter, an amplifier and a frequency divider, used to filter the beat frequency signal output by the photodetector through the bandpass filter and amplify it through the amplifier, and then reduce the frequency through the frequency divider to obtain a radio frequency signal.

[0012] As a further improvement of the present invention, the signal processing module includes an IQ phase detection unit and a phase extension unit. The IQ phase detection unit is used to decompose the radio frequency signal into in-phase components and quadrature components; compare the phases of the in-phase components and quadrature components to determine the phase difference; and after the phase difference is processed by the phase extension unit, continuous phase information and frequency conversion data are obtained.

[0013] As a further improvement of the present invention, the optical fiber frequency transmission field optical fiber noise simulation module includes a voltage output unit, a DDS output unit, a power amplifier, and a laboratory-wound optical fiber; the voltage output unit is used to convert continuous phase information and frequency conversion data into voltage data; a modulation depth parameter is set according to the voltage data, a third acousto-optic modulator is modulated according to the modulation depth parameter, and the length of the laboratory-wound optical fiber is adjusted according to the modulation result of the third acousto-optic modulator to achieve noise simulation; the modulation depth parameter data is output to the third acousto-optic modulator after passing through the DDS output unit and the power amplifier.

[0014] Secondly, the present invention also provides a method for simulating noise in a real fiber optic link for optical frequency transmission, comprising: splitting the laser generated by the laser into a reference light and a simulated light; modulating the simulated light and transmitting it in a real fiber optic network, and then performing optical frequency processing with the reference light to obtain a radio frequency signal;

[0015] After performing phase processing on the radio frequency signal, continuous phase information and frequency transformation data are obtained;

[0016] A field fiber optic noise simulation model for fiber optic frequency transmission is constructed. The phase information and frequency transformation data are converted into voltage data using the noise simulation model. Modulation depth parameters are set based on the voltage data. A third acousto-optic modulator is modulated based on the modulation depth parameters. The length of the laboratory wound fiber is adjusted based on the modulation result of the third acousto-optic modulator to achieve noise simulation.

[0017] As a further improvement of the present invention, the step of modulating the analog light and transmitting it in real fiber optics, and then performing optical frequency processing with the reference light to obtain a radio frequency signal specifically includes:

[0018] The simulated light is phase-modulated and then transmitted through a real fiber optic cable to obtain noisy simulated light.

[0019] The noisy analog light and reference light are superimposed by a photodetector and converted into a beat frequency signal;

[0020] After filtering and amplifying the beat frequency signal, a radio frequency signal is obtained by down-frequency processing.

[0021] As a further improvement of the present invention, the step of performing phase processing on the radio frequency signal to obtain continuous phase information and frequency conversion data specifically includes: decomposing the radio frequency signal into in-phase components and quadrature components; comparing the phases of the in-phase components and quadrature components to determine the phase difference; and obtaining continuous phase information and frequency conversion data after phase extension of the phase difference.

[0022] As a further improvement of the present invention, the laser is a narrow linewidth laser.

[0023] The beneficial effects of this invention are as follows: The method for simulating noise in a real-world fiber optic link for optical frequency transmission provided by this invention splits the laser generated by a laser into a reference light and a simulated light. After modulating the simulated light and transmitting it through a real fiber optic cable, it undergoes optical frequency processing with the reference light to obtain a radio frequency (RF) signal. This method can accurately simulate signal changes during actual optical fiber frequency transmission. This approach can capture the impact of different types and magnitudes of additional phase noise in the real fiber on the signal, providing a reliable data foundation for subsequent noise simulation. Phase processing of the RF signal yields continuous phase information and frequency transformation data, enabling in-depth analysis of the signal's phase characteristics and frequency changes. This data reflects the specific impact of real-world fiber optic noise on optical frequency transmission, facilitating the more accurate construction of noise simulation models. By converting the phase information and frequency transformation data into voltage data using the noise simulation model, and setting modulation depth parameters based on the voltage data, accurate simulation of real-world fiber optic noise can be achieved. By adjusting the length of the laboratory-wound fiber, the noise simulation effect can be further refined to more closely approximate the actual conditions of a real-world fiber. This provides an effective experimental means for studying the performance of optical fiber frequency transmission systems.

[0024] Constructing a real-world fiber optic noise simulation model for fiber optic frequency transmission allows for noise simulation experiments to be conducted in a laboratory environment, avoiding the inconvenience of expensive fiber optic resource leasing fees and complex communication equipment room environments. This significantly reduces testing costs while improving the operability and safety of the experiments. Through radio frequency signal processing and noise simulation, different types and magnitudes of noise simulation experiments can be quickly conducted in the laboratory without the need for lengthy testing on actual optical fibers. This improves experimental efficiency, enabling researchers to more quickly evaluate the performance of fiber optic frequency transmission systems.

[0025] Furthermore, filtering and amplifying the beat frequency signal can remove unnecessary noise interference while enhancing signal strength and improving the accuracy of subsequent processing. Down-frequency processing yields an RF signal, making it easier to process and analyze, providing a suitable signal form for subsequent phase processing and noise simulation.

[0026] Furthermore, decomposing the radio frequency signal into in-phase and quadrature components allows for a more detailed analysis of the signal characteristics. Precise phase processing provides more accurate input data for real-world fiber optic noise simulation in fiber optic frequency transmission. By obtaining continuous phase information and frequency transformation data, phase noise in real-world optical fibers can be simulated more realistically, improving the accuracy and reliability of noise simulation.

[0027] This invention provides a real-world fiber optic link noise simulation system for fiber optic frequency transmission. The system sequentially arranges modules along the optical path propagation direction, clearly simulating the actual process of fiber optic frequency transmission. Starting with laser generation, the light is split into reference and simulated light by an optical fiber coupler, then passes through an acousto-optic modulator, real optical fiber, and finally reaches the noise simulation module. The entire process is highly similar to a real fiber optic frequency transmission system, thus accurately simulating various noise conditions in real optical fibers. By performing phase processing on the radio frequency signal to obtain continuous phase information and frequency conversion data, and inputting this data into the noise simulation module to convert it into voltage data, the system accurately reflects the impact of real optical fiber noise on the optical frequency. Modulation depth parameters are set based on the voltage data, and the length of the laboratory-wound optical fiber is adjusted to simulate different types and magnitudes of real optical fiber noise, providing a reliable experimental method for studying the performance of fiber optic frequency transmission systems.

[0028] Furthermore, this system simulates real-world fiber optic noise in a laboratory environment using equipment such as fiber optic couplers, acousto-optic modulators, and laboratory-wound fiber optics, avoiding the expensive rental costs and complex operating environments required for testing on actual field fiber optics. This significantly reduces experimental costs while also improving the operability and safety of the experiments. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the actual measurement of fiber optic phase noise in an embodiment of the present invention;

[0031] Figure 2 This is a simulation system for real-world fiber optic phase noise in an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the simulation process for real-world fiber phase noise in an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0034] Explanation of related terms: IQ phase detector unit: Based on the processing of quadrature (I / Q) signals. In communication systems, signals are typically divided into in-phase (I) components and quadrature (Q) components. The I and Q components are two mutually orthogonal signals, which can be obtained by quadrature modulation of the input signal.

[0035] DDS (Direct Digital Synthesis) Output Unit: A modern frequency synthesis technology capable of outputting high-precision, high-stability signals. Existing DDS units mainly consist of a phase accumulator, a sine lookup table (ROM), a digital-to-analog converter (DAC), and a low-pass filter.

[0036] PD (PhotoDetector): A photodetector is a device that converts light signals into electrical signals.

[0037] FM (Faraday Rotator Mirror): A Faraday rotator mirror, an optical device based on the Faraday effect.

[0038] AOM (Acousto) Optic Modulator: An optical device that uses the acousto-optic effect to control the intensity, frequency, and direction of light.

[0039] OC (Optical Fiber Coupler): An optical device that couples optical signals from one or more input optical fibers to one or more output optical fibers.

[0040] FPGA (Field Programmable Gate Array) platform: A development and application environment built upon FPGA chips. FPGA chips contain numerous programmable logic units, memory units, digital signal processing units, etc., which can be configured and programmed according to user needs to implement various digital circuit functions.

[0041] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] Example 1

[0043] like Figures 1-2 As shown, this embodiment provides a fiber optic frequency transmission field fiber optic link noise simulation system, which includes, in sequence along the signal propagation direction: a laser, a fiber optic coupler, a first acousto-optic modulator, a photodetector, a signal processing module, and a fiber optic frequency transmission field fiber optic noise simulation module; the laser, fiber optic coupler, acousto-optic modulator, photodetector, and signal processing module are connected to each other via fiber optic links.

[0044] A laser is used to provide laser light. The laser light is input to an optical fiber coupler, which splits the laser light generated by the laser into reference light and analog light. The analog light is modulated by an acousto-optic modulator. After being transmitted through a real optical fiber, the modulated analog light and the reference light are input to a photodetector for optical frequency processing to obtain a radio frequency (RF) signal. The RF signal is input to a signal processing module for phase processing to obtain continuous phase information and frequency conversion data. The phase information and frequency conversion data are input to the optical fiber noise simulation module for optical frequency transmission, which converts them into voltage data. The modulation depth parameter is first set according to the voltage data, then modulation is performed according to the modulation depth parameter, and the fiber optic link length is adjusted according to the modulation result to achieve noise simulation.

[0045] Among them, the laser adopts a narrow linewidth laser. The narrow spectral linewidth and high stability can ensure the stability and accuracy of optical frequency signals during long-distance optical fiber transmission.

[0046] The fiber optic link noise simulation system also includes a first Faraday rotator and a second Faraday rotator; the first Faraday rotator is disposed between the photodetector and the fiber optic coupler, and is used to reflect the reference light to the photodetector; the second Faraday rotator is communicatively connected to the acousto-optic modulator through a real fiber, and is used to polarize and rotate the simulated light output from the real fiber by a set angle and reflect it to the photodetector.

[0047] The fiber optic link noise simulation system also includes a second acousto-optic modulator, which is connected via a real optical fiber and a second Faraday rotator. The driving frequency of the second acousto-optic modulator is a second set value; the second acousto-optic modulator is used to modulate the simulated light output from the real optical fiber.

[0048] The fiber optic link noise simulation system also includes a signal conversion module. This module is located between the photodetector and the signal processing module. The signal conversion module includes a bandpass filter, an amplifier, and a frequency divider. It is used to filter the beat frequency signal output from the photodetector through the bandpass filter, amplify it through the amplifier, and then down-convert it through the frequency divider to obtain the radio frequency signal.

[0049] The signal processing module includes an IQ phase detector unit and a phase extension unit. The IQ phase detector unit decomposes the RF signal into in-phase and quadrature components; it compares the phases of the in-phase and quadrature components to determine the phase difference; after processing by the phase extension unit, the phase difference yields continuous phase information and frequency conversion data. The data processing module is located in the FPGA chip and is configured and programmed through a set program to implement the functions of the data processing module.

[0050] The fiber optic frequency transmission field fiber optic noise simulation module includes a voltage output unit, a DDS output unit, a power amplifier, and laboratory-wound fiber. The voltage output unit converts continuous phase information and frequency conversion data into voltage data. Based on the voltage data, modulation depth parameters are set, and a third acousto-optic modulator is modulated according to these parameters. The length of the laboratory-wound fiber is then adjusted based on the modulation result of the third acousto-optic modulator to achieve noise simulation. This fiber optic frequency transmission field fiber optic noise simulation module is based on an FPGA platform. The FPGA platform includes storage units that store data obtained from the signal processing module. The data in these storage units is processed by the voltage output unit and set as modulation depth parameters. These modulation depth parameters are then processed by the DDS output unit and the power amplifier before being output to the third acousto-optic modulator. The laboratory-wound fiber is used to simulate real-world fiber optic transmission.

[0051] The specific noise simulation process is as follows: The laser light generated by the laser is split into 10% reference light and 90% analog light after passing through an optical fiber coupler. The 10% reference light is reflected into the photodetector after passing through a first Faraday rotator. The analog light passes through a first optical fiber acousto-optic modulator (AOM1, driving frequency ω1) and then enters the solid optical fiber for transmission. After transmission through the solid optical fiber, it is input to a second acousto-optic modulator AOM2 (driving frequency ω2) to obtain modulated analog light, which then passes through a second Faraday rotator FM2 (with a single pass polarization rotation of 45 degrees). At this point, the analog light is reflected by the second Faraday rotator FM2 and returns to the photodetector (PD) through the second acousto-optic modulator AOM2, the solid optical fiber, the first acousto-optic modulator AOM1, and the optical fiber coupler OC1.

[0052] The photodetector obtains the beat frequency signal EBEAT of the reference light and the returned analog light. After passing through a bandpass filter and amplification, it is then connected to a frequency divider to obtain the radio frequency signal E1. This signal is then fed into a signal processing module, where IQ phase detection and phase extension are performed to obtain the continuous phase information of the signal. The algorithm then obtains its continuous frequency change, resulting in continuous phase information and frequency transformation data, which is stored on an FPGA platform.

[0053] Next, the continuous phase information and frequency transformation data are input into the constructed fiber optic frequency transmission field fiber noise simulation module. The voltage output unit converts the continuous phase information and frequency transformation data into voltage data. Modulation depth parameters are set based on the voltage data, and a third acousto-optic modulator is modulated according to these parameters. At this point, the laboratory-wound fiber replaces the field fiber. The length of the laboratory-wound fiber is adjusted based on the modulation result of the third acousto-optic modulator to achieve noise simulation.

[0054] Example 2

[0055] like Figure 3 As shown, this embodiment provides a method for simulating noise in a real-world fiber optic link for optical frequency transmission. First, noise information from the real-world fiber is acquired. Then, modulation is performed based on the acquired noise information using a device. Finally, noise simulation is achieved by adjusting the length of the wound fiber in the laboratory. The specific implementation method is as follows.

[0056] S1. The laser generated by the laser is divided into reference light and analog light; the analog light is modulated and transmitted through optical fiber in the field, and then optical frequency processing is performed with the reference light to obtain a radio frequency signal.

[0057] Specifically, a narrow-linewidth laser is used, which splits the laser beam into a reference beam and an analog beam. In this embodiment, a narrow-linewidth laser is chosen because it can output a laser beam with a stable frequency and extremely narrow linewidth, which is crucial for applications requiring high-precision frequency measurements. The narrow linewidth reduces laser frequency fluctuations, improving system stability and measurement accuracy. These types of lasers are commonly used in precision measurement and communication systems, capable of generating laser beams with virtually no frequency drift. A high-precision beam splitter is used to separate the laser beam into the reference beam and the analog beam, ensuring consistency in power and frequency between the two.

[0058] The simulated light undergoes phase modulation and is then transmitted through a real fiber optic cable to obtain noisy simulated light. The reference light, after reflection, is directly input into a photodetector. The noisy simulated light and the reference light are superimposed by the photodetector to form a beat frequency signal. This beat frequency signal is then filtered, amplified, and down-converted to obtain a radio frequency signal. The simulated light is modulated by a phase modulator, which alters the phase of the light. This modulator is typically used to carry information or analog signals. However, when the phase-modulated simulated light signal is transmitted through the fiber, it is affected by the fiber's inherent characteristics (such as dispersion, loss, and nonlinear effects) and external environmental factors (such as temperature and vibration), resulting in noise. The simulated light transmitted through the real fiber carries this noise signal. In this embodiment, the noise signal includes signals such as fiber dispersion, nonlinear effects (such as self-phase modulation and four-wave mixing), fiber optic connector and splice losses, and external environmental factors (such as temperature fluctuations and mechanical vibrations).

[0059] When modulating based on equipment that acquires real-world fiber optic noise information, the modulation parameters need to be carefully adjusted and optimized. For example, based on the noise frequency, amplitude, and other characteristics in the real fiber optic cable, the modulation frequency, amplitude, and other parameters are adjusted to achieve a more accurate noise simulation. Furthermore, this embodiment can also employ other modulation techniques, such as digital modulation and analog modulation, to improve the accuracy and efficiency of modulation. This embodiment uses an acousto-optic modulator to perform phase modulation on the simulated light, changing the phase of the light wave by applying a signal to simulate phase noise in real-world fiber optic transmission.

[0060] Secondly, the noisy analog light and the unmodulated reference light are superimposed in a photodetector. Since the frequencies of the two lights are similar but slightly different, a beat frequency signal is generated. The frequency of the beat frequency signal is equal to the difference between the frequencies of the two beams and includes the noise information introduced by the analog light during transmission. During the process of converting the noisy analog light and the reference light into a beat frequency signal after being superimposed by the photodetector, it is necessary to ensure the accuracy and stability of the superposition.

[0061] The beat frequency signal is filtered to remove high-frequency noise and interference, and then amplified to improve the signal-to-noise ratio. Since the beat frequency signal may have a high frequency, direct processing can be difficult; therefore, it needs to be down-converted to a more suitable radio frequency band for subsequent processing. Furthermore, this embodiment employs a high-precision optical delay line and phase controller to precisely adjust the phase of the analog light and reference light to achieve optimal beat frequency performance, thereby obtaining a more accurate beat frequency signal.

[0062] S2. Perform phase processing on the radio frequency signal to obtain continuous phase information and frequency transformation data.

[0063] Furthermore, the radio frequency signal is decomposed into in-phase and quadrature components; the phase difference is determined by comparing the phases of the in-phase and quadrature components; the phase difference is then extended to obtain continuous phase information and frequency conversion data. The phase difference reflects the phase change of analog light during transmission and includes noise information. In determining the phase difference by comparing the phases of the in-phase and quadrature components, this embodiment uses a high-precision phase comparator to ensure accurate measurement of the phase difference. Simultaneously, to improve the accuracy and reliability of the phase comparison, this embodiment also performs appropriate filtering and amplification processing on the in-phase and quadrature components.

[0064] S3. To accurately simulate these noise characteristics, a field optical fiber noise simulation model for optical frequency transmission is constructed. The model converts phase information and frequency transformation data into voltage data. Modulation depth parameters are set based on the voltage data. A third acousto-optic modulator is then used to modulate the signal based on these parameters. The length of the laboratory-wound optical fiber is adjusted according to the modulation result of the third acousto-optic modulator to achieve noise simulation. The converted voltage data reflects the impact of modulation depth and optical fiber transmission on the optical signal and can be used to set the modulation depth parameters. This noise simulation model not only considers the sources and properties of noise but also introduces modulation depth and fiber length as key parameters. By adjusting these parameters, we can simulate the optical signal transmission process under different conditions.

[0065] The modulation depth parameter is set based on voltage data to modulate the simulated light. The length of the lab-wound optical fiber is then adjusted based on the modulation results to simulate the noise characteristics of real-world fiber optic transmission. This is a closed-loop feedback process; through continuous adjustment and optimization, the lab environment can more accurately simulate the noise conditions of real-world fiber optic transmission.

[0066] During the model construction process, various practical factors were fully considered to ensure the accuracy and reliability of the model. Using this meticulously constructed noise simulation model, phase information and frequency transformation data were converted into voltage data. After obtaining the voltage data, its characteristics were carefully analyzed, and the modulation depth parameter was set appropriately based on these characteristics. The setting of this parameter is crucial, as it directly affects the subsequent modulation effect.

[0067] Modulation was performed according to the pre-set modulation depth parameters. During modulation, changes in various indicators were closely monitored to ensure the accuracy and stability of the modulation. Simultaneously, the length of the laboratory-wound optical fiber was adjusted based on the modulation results to achieve more accurate noise simulation. Through continuous adjustment and optimization, the noise simulation effect became closer to reality, providing a more reliable basis for subsequent research and applications.

[0068] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A field fiber optic link noise simulation system for fiber optic frequency transmission, characterized in that, The system comprises, sequentially along the signal propagation direction, a laser, an optical fiber coupler, an acousto-optic modulator, a photodetector, a signal processing module, and a fiber optic frequency transmission real-world fiber noise simulation module. The laser, optical fiber coupler, acousto-optic modulator, photodetector, and signal processing module are interconnected via optical fiber links. It also includes a second acousto-optic modulator, a second Faraday rotator, and a signal conversion module. The second acousto-optic modulator is connected to the second Faraday rotator via a real-world optical fiber, and its driving frequency is a second preset value. The signal conversion module is positioned between the photodetector and the signal processing module. The second Faraday rotator is communicatively connected to the acousto-optic modulator via a real-world optical fiber. The laser is used to provide laser light, and the laser light is input to an optical fiber coupler to split the laser light generated by the laser into reference light and analog light; The simulated light is modulated by an acousto-optic modulator. After the modulated simulated light is transmitted through a real optical fiber, the second Faraday rotator is used to rotate the simulated light output from the real optical fiber by a set angle and reflect it into a photodetector. The reflected simulated light and the reference light are input into the photodetector for optical frequency processing to obtain a radio frequency signal. The radio frequency signal is input to the signal processing module for phase processing to obtain continuous phase information and frequency conversion data. The signal processing module includes an IQ phase detection unit and a phase extension unit. The IQ phase detection unit is used to decompose the radio frequency signal into in-phase components and quadrature components; compare the phases of the in-phase components and quadrature components to determine the phase difference; after the phase difference is processed by the phase extension unit, continuous phase information and frequency conversion data are obtained; the module also includes a storage unit for storing the continuous phase information and frequency conversion data. The phase information and frequency transformation data in the storage unit are input into the fiber optic frequency transmission field fiber noise simulation module, converted into voltage data, and then the modulation depth parameter is set according to the voltage data. Modulation is then performed according to the modulation depth parameter, and the fiber optic link length is adjusted according to the modulation result to achieve noise simulation. The fiber optic frequency transmission field fiber noise simulation module includes a voltage output unit, a DDS output unit, a power amplifier, and laboratory-wound fiber. The voltage output unit is used to convert continuous phase information and frequency transformation data into voltage data. The modulation depth parameter is set according to the voltage data, and modulation is performed on a third acousto-optic modulator according to the modulation depth parameter. The length of the laboratory-wound fiber is adjusted according to the modulation result of the third acousto-optic modulator to achieve noise simulation. The modulation depth parameter data is output to the third acousto-optic modulator after passing through the DDS output unit and the power amplifier. The signal conversion module includes a bandpass filter, an amplifier, and a frequency divider. It is used to filter the beat frequency signal output by the photodetector through the bandpass filter, amplify it through the amplifier, and then reduce the frequency through the frequency divider to obtain a radio frequency signal.

2. The fiber optic frequency transmission field fiber optic link noise simulation system according to claim 1, characterized in that, It also includes a first Faraday rotator; the first Faraday rotator is disposed between the photodetector and the fiber coupler, and the Faraday rotator is used to reflect reference light to the photodetector.

3. A method for simulating noise in a real-world fiber optic link for optical frequency transmission, characterized in that, include: The laser beam generated by the laser is divided into reference light and analog light; After modulating the analog light and transmitting it through real fiber optics, the radio frequency signal is obtained by optical frequency processing with the reference light. After performing phase processing on the radio frequency signal, continuous phase information and frequency transformation data are obtained; A field fiber optic noise simulation model for fiber optic frequency transmission is constructed. The phase information and frequency transformation data are converted into voltage data using the noise simulation model. Modulation depth parameters are set according to the voltage data. A third acousto-optic modulator is modulated according to the modulation depth parameters. The length of the laboratory wound fiber is adjusted according to the modulation result of the third acousto-optic modulator to achieve noise simulation. The process of modulating the analog light and transmitting it through a real fiber optic cable, then performing optical frequency processing with a reference light to obtain a radio frequency (RF) signal, and finally performing phase processing on the RF signal to obtain continuous phase information and frequency conversion data, specifically includes: The simulated light is phase-modulated and then transmitted through a real fiber optic cable to obtain noisy simulated light. The noisy analog light and reference light are superimposed by a photodetector and converted into a beat frequency signal; After filtering and amplifying the beat frequency signal, and then down-frequency processing is performed to obtain the radio frequency signal; The radio frequency signal is decomposed into in-phase and quadrature components; the phase difference is determined by comparing the phases of the in-phase and quadrature components. The phase difference is extended to obtain continuous phase information and frequency transformation data.

4. The method for simulating optical fiber link noise in real-world optical fiber frequency transmission according to claim 3, characterized in that, The laser is a narrow linewidth laser.

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