Optical fiber optical frequency transmission field optical fiber link noise simulation method and system

Abstract

The invention 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, and the method comprises the steps: dividing laser generated by a laser into reference light and simulation light; modulating the analog light, performing field optical fiber transmission, and performing optical frequency processing on the analog light and the reference light to obtain a radio frequency signal; performing phase processing on the radio frequency signal to obtain continuous phase information and frequency conversion data; the method comprises the following steps: constructing an optical fiber optical frequency transmission field optical fiber noise simulation model, converting phase information and frequency conversion data into voltage data by using the noise simulation model, setting a modulation depth parameter according to the voltage data, performing modulation according to the modulation depth parameter, and adjusting the length of a laboratory winding optical fiber according to a modulation result to realize noise simulation. According to the method, different types and different magnitudes of field optical fiber link noise can be simulated.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber communication, and in particular to a method and system for simulating noise of an optical fiber link in a field of optical fiber optical frequency transmission. Background Art

[0002] High-precision optical frequency transmission technology based on optical fiber is an important means to achieve long-distance stable transmission comparison of high-precision optical clock standard frequency signals. However, due to different laying methods, field optical fibers will have different types and magnitudes of additional phase noise, which will affect the transmission stability of the optical frequency system. In order to more efficiently complete the measurement and evaluation of the performance indicators of the fiber optical frequency transmission system, it is necessary to conduct high-precision fiber optical frequency transmission test experiments under different types and magnitudes of phase noise. However, the cost of renting optical fiber resources is expensive, and the complex environment of the communication room makes it difficult to carry out experimental tests, resulting in the inability to simulate different types and magnitudes of field optical fiber additional phase noise. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method and system for simulating field optical fiber link noise in optical fiber optical frequency transmission in view of the deficiencies in the above-mentioned prior art, so as to solve the technical problem that different types and magnitudes of field optical fiber additional phase noise cannot be simulated.

[0004] The objective of the present invention is achieved by the following technical solutions: In the first aspect, the present invention provides a fiber optic frequency transmission field fiber optic link noise simulation system, which includes: 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 in sequence along the signal propagation direction; the laser, the fiber optic coupler, the acousto-optic modulator, the photodetector and the signal processing module are connected to each other through a fiber optic link; The laser is used to provide laser light, and the laser light is input to the optical fiber coupler, which is used to separate the laser light generated by the laser into reference light and simulation light; The analog light is modulated by an acousto-optic modulator, and after the modulated analog light is transmitted through a field optical fiber, it is input into a photodetector together with a reference light for optical frequency processing to obtain a radio frequency signal; The radio frequency signal is input into 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 into the fiber optic frequency transmission field fiber optic noise simulation module and converted into voltage data. The modulation depth parameter is first set according to the voltage data, and then modulation is performed according to the modulation depth parameter. The fiber optic link length is adjusted according to the modulation result to realize noise simulation.

[0005] 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 arranged 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 solid optical fiber, and the second Faraday rotator is used to rotate the polarization of the simulated light output from the solid optical fiber at a set angle and reflect it to the photodetector.

[0006] As a further improvement of the present invention, it also includes a second acousto-optic modulator, which is connected to the second Faraday rotator through a solid optical fiber, 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 solid optical fiber.

[0007] As a further improvement of the present invention, it also includes a signal conversion module; the signal conversion module is arranged between the photodetector and the signal processing module; the signal conversion module includes a bandpass filter, an amplifier and a frequency divider, which is used to filter the beat frequency signal output by the photodetector through the bandpass filter and amplify it through the amplifier, and then down-convert it through the frequency divider to obtain a radio frequency signal.

[0008] As a further improvement of the present invention, the signal processing module includes an IQ phase detection unit and a phase extension unit, wherein the IQ phase detection unit is used to decompose the radio frequency signal into an in-phase component and an orthogonal component; compare the phases of the in-phase component and the orthogonal component 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.

[0009] As a further improvement of the present invention, the fiber optical frequency transfer field fiber noise simulation module includes a voltage output unit, a DDS output unit, a power amplifier and a laboratory wound fiber; the voltage output unit is used to convert continuous phase information and frequency conversion data into voltage data; the modulation depth parameter is set according to the voltage data, the second acousto-optic modulator is modulated according to the modulation depth parameter, and the length of the laboratory wound fiber is adjusted according to the modulation result of the second acousto-optic modulator to realize noise simulation; the modulation depth parameter data is output to the second acousto-optic modulator after passing through the DDS output unit and the power amplifier.

[0010] In a second aspect, the present invention further provides a method for simulating noise in a field optical fiber link of optical frequency transmission in an optical fiber, comprising: The laser light generated by the laser is divided into reference light and analog light; after the analog light is modulated and transmitted through the actual optical fiber, the optical frequency processing is performed with the reference light to obtain the radio frequency signal; After performing phase processing on the radio frequency signal, continuous phase information and frequency conversion data are obtained; A field fiber optic noise simulation model for fiber optic frequency transmission is constructed, and the phase information and frequency conversion data are converted into voltage data using the noise simulation model. Modulation depth parameters are set according to the voltage data, modulation is performed according to the modulation depth parameters, and the length of the laboratory wound optical fiber is adjusted according to the modulation results to achieve noise simulation. As a further improvement of the present invention, the analog light is modulated and transmitted through a field optical fiber, and then optical frequency processed with a reference light to obtain a radio frequency signal, specifically including: The simulated light is phase modulated and transmitted through a field optical fiber to obtain simulated light with noise; The simulated light with noise and the reference light are superimposed through a photodetector and converted into a beat frequency signal; The beat frequency signal is filtered and amplified, and then down-converted to obtain a radio frequency signal.

[0011] As a further improvement of the present invention, the phase processing of the radio frequency signal to obtain continuous phase information and frequency conversion data specifically includes: decomposing the radio frequency signal into an in-phase component and an orthogonal component; comparing the phases of the in-phase component and the orthogonal component to determine the phase difference; and obtaining continuous phase information and frequency conversion data after phase stretching the phase difference.

[0012] As a further improvement of the present invention, the laser is a narrow line width laser.

[0013] The beneficial effects of the present invention are as follows: the noise simulation method of a field optical fiber link in optical frequency transmission of optical fiber provided by the present invention can accurately simulate the signal changes in the actual optical fiber optical frequency transmission process by dividing the laser generated by the laser into reference light and simulation light, and modulating the simulation light and performing optical frequency processing with the reference light after field optical fiber transmission to obtain a radio frequency signal. This method can capture the influence of different types and magnitudes of additional phase noise on the signal in the field optical fiber, and provide a real and reliable data basis for subsequent noise simulation. The radio frequency signal is phase processed to obtain continuous phase information and frequency conversion data, which can deeply analyze the phase characteristics and frequency changes of the signal. These data can reflect the specific influence of field optical fiber noise on optical frequency transmission, and help to more accurately construct a noise simulation model. The noise simulation model is used to convert the phase information and frequency conversion data into voltage data, and the modulation depth parameters are set according to the voltage data for modulation, so as to realize the accurate simulation of field optical fiber noise. By adjusting the length of the laboratory winding optical fiber, the effect of the noise simulation can be further adjusted to make it closer to the actual field optical fiber. This provides an effective experimental means for studying the performance of the optical fiber optical frequency transmission system.

[0014] By building a field fiber noise simulation model for fiber optical frequency transmission, noise simulation experiments can be conducted in a laboratory environment, avoiding the inconvenience caused by expensive fiber resource rental fees and complex communication room environments. This greatly reduces the cost of testing, while also improving the operability and safety of the experiment. By processing RF signals and simulating noise, noise simulation experiments of different types and magnitudes can be quickly conducted in the laboratory without the need for long-term testing on actual field optical fibers. This improves experimental efficiency and enables researchers to more quickly evaluate the performance of fiber optical frequency transmission systems.

[0015] Furthermore, filtering and amplifying the beat frequency signal can remove unnecessary noise interference, while enhancing the strength of the signal and improving the accuracy of subsequent processing. The RF signal obtained by down-conversion processing makes the signal easier to process and analyze, providing a suitable signal form for subsequent phase processing and noise simulation.

[0016] Furthermore, decomposing the RF signal into in-phase components and orthogonal components can more carefully analyze the characteristics of the signal. The precise phase processing process can provide more accurate input data for the field fiber noise simulation of fiber optical frequency transmission. By obtaining continuous phase information and frequency conversion data, the phase noise in the field fiber can be simulated more realistically, improving the accuracy and reliability of noise simulation.

[0017] The present invention provides a field fiber link noise simulation system for fiber optical frequency transmission. Various modules are sequentially arranged along the propagation direction of the optical path, and the actual process of fiber optical frequency transmission can be clearly simulated. Starting from the generation of laser light by the laser, it is divided into reference light and simulation light through the fiber coupler, and then passes through the acousto-optic modulator, field optical fiber and other links, and finally reaches the noise simulation module. The whole process is highly similar to the actual fiber optical frequency transmission system, so that various noise conditions in the field optical fiber can be accurately simulated. By performing phase processing on the radio frequency signal to obtain continuous phase information and frequency conversion data, and inputting them into the noise simulation module to convert them into voltage data, the influence of field optical fiber noise on optical frequency can be accurately reflected. By setting the modulation depth parameter according to the voltage data for modulation, and adjusting the length of the laboratory winding optical fiber, the simulation of field optical fiber noise of different types and magnitudes can be realized, which provides a reliable experimental means for studying the performance of the fiber optical frequency transmission system.

[0018] In addition, the system uses fiber couplers, acousto-optic modulators, and laboratory-wound optical fibers to simulate field fiber noise in a laboratory environment, avoiding the expensive rental costs and complex operating environment required for testing on actual field optical fibers. This greatly reduces experimental costs while also improving the operability and safety of the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 is a schematic diagram of measuring field optical fiber phase noise in an embodiment of the present invention; Figure 2 It is a simulation system of field optical fiber phase noise in an embodiment of the present invention; Figure 3 It is a schematic diagram of the simulation process of the actual optical fiber phase noise in the embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Explanation of relevant terms: IQ phase detector: Based on the processing of orthogonal (I / Q) signals. In communication systems, signals are usually divided into in-phase (I) components and quadrature (Q) components. The I component and the Q component are two mutually orthogonal signals that can be obtained by orthogonal modulation of the input signal.

[0023] DDS (Direct Digital Synthesis) output unit: Direct digital frequency synthesis output unit, a modern frequency synthesis technology, can output high-precision and high-stability signals. The existing DDS is mainly composed of a phase accumulator, a sine lookup table (ROM), a digital-to-analog converter (DAC) and a low-pass filter.

[0024] PD (PhotoDetector): Photodetector, a device that converts light signals into electrical signals.

[0025] FM (Faraday Rotator Mirror): Faraday rotator mirror, an optical device based on the Faraday effect.

[0026] AOM (Acousto-Optic Modulator): An optical device that uses the acousto-optic effect to control the intensity, frequency, and direction of light.

[0027] OC (Optical Fiber Coupler): An optical device that can couple optical signals from one or more input optical fibers to one or more output optical fibers.

[0028] FPGA (Field Programmable Gate Array) platform: a field programmable gate array; a development and application environment built on FPGA chips. FPGA chips contain a large number of programmable logic units, storage units, digital signal processing units, etc., which can be configured and programmed according to user needs to realize various digital circuit functions.

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, wherein the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0030] Example 1 like Figure 1-Figure 2 As shown, this embodiment provides a fiber optic frequency transmission field fiber optic link noise simulation system, which includes: 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 along the signal propagation direction; the laser, the fiber optic coupler, the acousto-optic modulator, the photodetector and the signal processing module are communicatively connected through a fiber optic link.

[0031] The laser is used to provide laser light, which is input to the fiber coupler to separate the laser light generated by the laser into reference light and analog light; the analog light is modulated by the acousto-optic modulator, and the modulated analog light is transmitted through the field optical fiber, and then input to the photodetector with the reference light 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 phase information and frequency conversion data are input to the fiber noise simulation module of the optical fiber optical frequency transmission field and converted into voltage data, and the modulation depth parameters are first set according to the voltage data, and then modulation is performed according to the modulation depth parameters, and the fiber link length is adjusted according to the modulation result to realize noise simulation.

[0032] Among them, the laser uses a narrow linewidth laser. The narrow spectral linewidth and high stability can ensure the stability and accuracy of the optical frequency signal during long-distance optical fiber transmission.

[0033] The optical fiber link noise simulation system also includes a first Faraday rotator and a second Faraday rotator; the first Faraday rotator is arranged between the photodetector and the optical fiber coupler, and is used to reflect the reference light to the photodetector; the second Faraday rotator is connected to the acousto-optic modulator through a real optical fiber, and is used to rotate the polarization of the simulated light output from the real optical fiber at a set angle and reflect it to the photodetector.

[0034] The fiber link noise simulation system also includes a second acousto-optic modulator, which is connected to the second Faraday rotator through a field optical fiber. 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 through the field optical fiber.

[0035] The optical fiber link noise simulation system also includes a signal conversion module. The signal conversion module is arranged between the photodetector and the signal processing module. The signal conversion module includes a bandpass filter, an amplifier and a frequency divider, which is used to filter the beat frequency signal output by the photodetector through the bandpass filter, amplify it through the amplifier, and then down-convert it through the frequency divider to obtain a radio frequency signal.

[0036] 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 RF signal into an in-phase component and an orthogonal component; the phase of the in-phase component and the orthogonal component is compared 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 data processing module is arranged in the FPGA chip, and is configured and programmed through the set program to realize the functions in the data processing module.

[0037] The field fiber noise simulation module of optical fiber frequency transmission of optical fiber 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; the modulation depth parameter is set according to the voltage data, the second 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 second acousto-optic modulator to realize noise simulation. The field fiber noise simulation module of optical fiber frequency transmission of optical fiber is an FPGA platform. A storage unit for storing data is arranged in the FPGA platform, which can store the data obtained in the signal processing module, and the data in the storage unit is set as the modulation depth parameter after being processed by the voltage output unit. The set modulation depth parameter data is processed by the DDS output unit and the power amplifier and output to the second acousto-optic modulator. The laboratory wound optical fiber is used to simulate the field optical fiber.

[0038] The specific simulation process of noise is: After the laser generated by the laser passes through the fiber coupler, it is divided into 10% reference light and 90% simulation light. Among them, 10% of the reference light passes through the first Faraday rotator and is reflected to the photodetector. After the simulation light passes through the first fiber acousto-optic modulator (AOM1, the driving frequency is ω1), it enters the real optical fiber for transmission. After the real optical fiber transmission, it is input to the second acousto-optic modulator AOM2 (the driving frequency is ω2) to obtain the modulated simulation light, and then passes through the second Faraday rotator FM2 (single pass polarization rotation 45 degrees). At this time, the simulation light is reflected by the second Faraday rotator FM2, and returns to the photodetector (PD, PhotoDetector) again through the second acousto-optic modulator AOM2, the real optical fiber, the first acousto-optic modulator AOM1 and the fiber coupler OC1.

[0039] The photodetector obtains the beat signal EBEAT of the reference light and the returned analog light, passes through a bandpass filter and amplifies it, and then connects it to a 2-way divider to obtain the RF signal E1. The signal is connected to the signal processing module, and the continuous phase information of the signal is obtained through the IQ phase detection and phase extension in the signal processing module. The continuous frequency change is obtained through the algorithm, and the continuous phase information and frequency conversion data are obtained, and the data is stored through the FPGA platform.

[0040] Next, the continuous phase information and frequency conversion data are input into the constructed fiber optic frequency transfer field fiber noise simulation module, and the continuous phase information and frequency conversion data are converted into voltage data through the voltage output unit. The modulation depth parameter is set according to the voltage data, and the second acousto-optic modulator is modulated according to the modulation depth parameter. At this time, the laboratory wound fiber replaces the field fiber. According to the modulation result of the second acousto-optic modulator, the length of the laboratory wound fiber is adjusted to realize noise simulation.

[0041] Example 2 like Figure 3 As shown, this embodiment provides a method for simulating noise of a field optical fiber link in optical fiber optical frequency transmission, firstly by obtaining noise information in the field optical fiber, modulating based on the device for obtaining the field optical fiber noise information, and then adjusting the length of the winding optical fiber in the laboratory to achieve noise simulation. The following is a specific implementation method.

[0042] S1. The laser light generated by the laser is divided into reference light and analog light; the analog light is modulated and transmitted through a field optical fiber, and then optical frequency processing is performed with the reference light to obtain a radio frequency signal.

[0043] Specifically, the laser uses a narrow linewidth laser, and the laser generated by the narrow linewidth laser is divided into reference light and simulation light. Specifically, the narrow linewidth laser is selected in this embodiment because it can output a laser with stable frequency and extremely narrow linewidth, which is crucial for applications that require high-precision frequency measurement. The narrow linewidth reduces the fluctuation of the laser frequency and improves the stability and measurement accuracy of the system. This type of laser is commonly used in precision measurement and communication systems, and can produce a laser beam with almost no frequency drift. A high-precision spectrometer is used to divide the laser beam into two parts: reference light and simulation light, ensuring the consistency of the two in power and frequency.

[0044] After the analog light is phase modulated and transmitted through a field optical fiber, an analog light with noise is obtained; and the reference light is directly input into the photodetector after reflection. The analog light with noise and the reference light are superimposed on the photodetector and converted into a beat frequency signal; the beat frequency signal is filtered and amplified, and then down-converted to obtain a radio frequency signal. The analog light is modulated by a phase modulator, which can change the phase of the light and is usually used to carry information or analog signals. When the analog light signal after phase modulation is transmitted in the optical fiber, it will be affected by the characteristics of the optical fiber itself (such as dispersion, loss, nonlinear effects) and the external environment (such as temperature and vibration), thereby generating noise. The analog light after passing through the field optical fiber carries a noise signal. In this embodiment, the noise signal includes signals such as dispersion of the optical fiber, nonlinear effects (such as self-phase modulation, four-wave mixing, etc.), loss of optical fiber joints and connectors, and external environmental factors (such as temperature fluctuations and mechanical vibrations).

[0045] When performing modulation based on a device that obtains field optical fiber noise information, the modulation parameters need to be carefully adjusted and optimized. For example, according to the characteristics of the noise frequency, amplitude, etc. in the field optical fiber, the modulation frequency, amplitude, and other parameters are adjusted to achieve more accurate noise simulation. In addition, this embodiment can also use other modulation technologies, such as digital modulation, analog modulation, etc., to improve the accuracy and efficiency of modulation. This embodiment uses an acousto-optic modulator to phase modulate the simulated light, and changes the phase of the light wave by applying a signal to simulate the phase noise in field optical fiber transmission.

[0046] Secondly, the noisy analog light and the unmodulated reference light are superimposed in the photodetector. Since the two have similar but slightly different frequencies, a beat signal will be generated. The frequency of the beat signal is equal to the difference between the frequencies of the two beams of light, and contains the noise information introduced by the analog light during the transmission process. After the noisy analog light and the reference light are superimposed in the photodetector, the accuracy and stability of the superposition must be ensured in the process of converting them into a beat signal.

[0047] The beat frequency signal is filtered to remove high-frequency noise and interference, and then amplified to improve the signal-to-noise ratio of the signal. Since the frequency of the beat frequency signal may be high, it may be difficult to process it directly, so it is necessary to perform frequency reduction processing to convert it to a radio frequency band that is more suitable for subsequent processing. In addition, in this embodiment, a high-precision optical delay line and phase controller are used to accurately adjust the phase of the analog light and the reference light to achieve the best beat frequency effect, thereby obtaining a more accurate beat frequency signal.

[0048] S2. Perform phase processing on the RF signal to obtain continuous phase information and frequency conversion data.

[0049] Further, the RF signal is decomposed into an in-phase component and an orthogonal component; the phases of the in-phase component and the orthogonal component are compared to determine the phase difference; the phase difference is phase stretched to obtain continuous phase information and frequency conversion data. The phase difference reflects the change in the phase of the simulated light during the transmission process and contains noise information. In the process of comparing the phases of the in-phase component and the orthogonal component to determine the phase difference, this embodiment uses a high-precision phase comparator to ensure that the measurement of the phase difference is accurate. At the same time, in order to improve the accuracy and reliability of the phase comparison, this embodiment also performs appropriate filtering and amplification processing on the in-phase component and the orthogonal component.

[0050] S3. In order to accurately simulate these noise characteristics, a field fiber noise simulation model of fiber optical frequency transmission is constructed. The phase information and frequency conversion data are converted into voltage data using the noise simulation model. The modulation depth parameters are set according to the voltage data, and modulation is performed according to the modulation depth parameters. The length of the fiber wound in the laboratory is adjusted according to the modulation results to achieve noise simulation. Among them, the converted voltage data can reflect the influence of modulation depth and fiber transmission on the optical signal, and can be used to set the modulation depth parameters. This noise simulation model not only considers the source and nature of the 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.

[0051] The modulation depth parameters are set according to the voltage data, the simulated light is modulated, and the length of the fiber wound in the laboratory is adjusted according to the modulation results to simulate the noise characteristics in the field fiber transmission. This is a closed-loop feedback process. Through continuous adjustment and optimization, the laboratory environment can more accurately simulate the noise conditions of field fiber transmission.

[0052] During the construction process, various practical factors are fully considered to ensure the accuracy and reliability of the model. Using this carefully constructed noise simulation model, the phase information and frequency conversion data are converted into voltage data. After obtaining the voltage data, its characteristics are carefully analyzed and the modulation depth parameters are reasonably set according to these characteristics. The setting of this parameter is crucial and will directly affect the subsequent modulation effect.

[0053] Perform modulation operations according to the set modulation depth parameters. During the modulation process, pay close attention to the changes in various indicators to ensure the accuracy and stability of the modulation. At the same time, adjust the length of the fiber wound in the laboratory according to the modulation results to achieve more accurate noise simulation. Through continuous adjustment and optimization, the effect of noise simulation is closer to the actual situation, providing a more reliable basis for subsequent research and application.

[0054] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A fiber optic frequency transmission field fiber optic link noise simulation system, characterized in that: The system includes: a laser, a fiber coupler, an acousto-optic modulator, a photodetector, a signal processing module and a fiber optical frequency transmission field fiber noise simulation module in sequence along the signal propagation direction; the laser, the fiber coupler, the acousto-optic modulator, the photodetector and the signal processing module are connected to each other through a fiber link; The laser is used to provide laser light, and the laser light is input to the optical fiber coupler, which is used to separate the laser light generated by the laser into reference light and simulation light; The analog light is modulated by an acousto-optic modulator, and after being transmitted through a field optical fiber, the modulated analog light is input into a photodetector together with a reference light for optical frequency processing to obtain a radio frequency signal; The radio frequency signal is input into 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 into the fiber optic frequency transmission field fiber optic noise simulation module and converted into voltage data. The modulation depth parameter is first set according to the voltage data, and then modulation is performed according to the modulation depth parameter. The fiber optic link length is adjusted according to the modulation result to realize noise simulation.

2. The fiber optical frequency transmission field fiber link noise simulation system according to claim 1 is characterized in that: It also includes a first Faraday rotator and a second Faraday rotator; the first Faraday rotator is arranged 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 connected to the acousto-optic modulator through a field optical fiber, and the second Faraday rotator is used to rotate the polarization of the simulated light output from the field optical fiber at a set angle and reflect it to the photodetector.

3. The fiber optical frequency transmission field fiber link noise simulation system according to claim 1, characterized in that: It also includes a second acousto-optic modulator, which is connected to the second Faraday rotator through a solid optical fiber, 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 solid optical fiber.

4. The fiber optical frequency transmission field fiber link noise simulation system according to claim 2 or 3, characterized in that: It also includes a signal conversion module; the signal conversion module is arranged between the photodetector and the signal processing module; the signal conversion module includes a bandpass filter, an amplifier and a frequency divider, which is 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.

5. The fiber optical frequency transmission field fiber link noise simulation system according to claim 1, characterized in that: The signal processing module includes an IQ phase detection unit and a phase extension unit, wherein the IQ phase detection unit is used to decompose the radio frequency signal into an in-phase component and an orthogonal component; compare the phases of the in-phase component and the orthogonal component 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.

6. The fiber optical frequency transmission field fiber link noise simulation system according to claim 1, characterized in that: The fiber optical frequency transfer field fiber noise simulation module comprises a voltage output unit, a DDS output unit, a power amplifier and a laboratory wound 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 second acousto-optic modulator is modulated according to the modulation depth parameter, and the length of the laboratory wound fiber is adjusted according to the modulation result of the second acousto-optic modulator to realize noise simulation; the modulation depth parameter data is output to the second acousto-optic modulator after passing through the DDS output unit and the power amplifier.

7. A method for simulating noise in a field optical fiber link for optical frequency transmission of optical fiber, characterized in that: include: Splitting the laser light generated by the laser into reference light and simulation light; After the analog light is modulated and transmitted through a real optical fiber, 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 conversion data are obtained; A field fiber optic noise simulation model for fiber optic frequency transmission is constructed, and the phase information and frequency conversion data are converted into voltage data using the noise simulation model. Modulation depth parameters are set according to the voltage data, modulation is performed according to the modulation depth parameters, and the length of the laboratory wound optical fiber is adjusted according to the modulation results to achieve noise simulation.

8. The method for simulating noise of a fiber link in the field of optical fiber optical frequency transmission according to claim 7, characterized in that: The analog light is modulated and transmitted through a field optical fiber, and then optical frequency processed with a reference light to obtain a radio frequency signal, specifically including: The simulated light is phase modulated and transmitted through a field optical fiber to obtain simulated light with noise; The simulated light with noise and the reference light are superimposed through a photodetector and converted into a beat frequency signal; The beat frequency signal is filtered and amplified, and then down-converted to obtain a radio frequency signal.

9. The method for simulating noise of a fiber link in the field of optical fiber optical frequency transmission according to claim 8, characterized in that: The method 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 an in-phase component and an orthogonal component; comparing the phases of the in-phase component and the orthogonal component to determine the phase difference; and obtaining continuous phase information and frequency conversion data after phase extension of the phase difference.

10. The method for simulating noise of a fiber link in the field of optical fiber optical frequency transmission according to claim 7, characterized in that: The laser is a narrow line width laser.

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