Optical frequency comb stabilized fiber link latency jitter system

Abstract

The application discloses an optical frequency comb stabilizes a fiber link delay jitter system, and belongs to the technical field of optical frequency combs.The system comprises the following: an optical frequency comb, which is used for providing a comb-shaped optical signal and transmitting the same to an interference unit; the interference unit, which is used for interfering the comb-shaped optical signal from the optical frequency comb; a round-trip correction unit, which is used for reversely isolating and frequency modulating the optical signal after interference, and transmitting the optical signal to a double optical secondary mixing unit after splitting; and the double optical secondary mixing unit, which is used for obtaining a zero-frequency voltage signal through photoelectric conversion, and taking the zero-frequency voltage signal as an input voltage signal of a tunable delay line after processing by a proportional integral controller, so as to control the delay jitter of the fiber link.The application significantly improves the precision and real-time performance of the fiber link delay jitter control, and effectively guarantees the stability and reliability of the fiber link signal transmission.

Description

Technical Field

[0001] This invention belongs to the field of optical frequency comb technology, and particularly relates to an optical frequency comb-stabilized fiber optic link delay jitter system. Background Technology

[0002] In fiber optic communication systems, the delay jitter of fiber optic links has a significant impact on the stability and accuracy of signal transmission. In particular, in critical application scenarios such as high-precision measurement and optical communication network synchronization, effective control of delay jitter is of paramount importance.

[0003] However, existing technologies for monitoring and compensating for delay jitter in fiber optic links have significant drawbacks: traditional delay detection methods struggle to accurately capture subtle changes in optical frequency domain signals, resulting in insufficient accuracy in sensing delay jitter and an inability to compensate in real time and effectively, thus affecting the overall system performance.

[0004] In 2022, Zhang Xiang et al. from the Chinese Academy of Sciences proposed a method for stable frequency transmission of coherent optical direct-frequency fiber links, which requires expensive ultra-stable lasers, resulting in high costs. Zhang Fan et al. from the Quantum Information and Measurement Laboratory of Peking University used the phase difference of higher-order harmonics between the local end signal and the remote return signal of a femtosecond mode-locked laser to test loop delay jitter. After calculating the phase difference by computer, they controlled the digital signal to drive the fiber delay line to compensate for the loop delay jitter. The controllable test bench simulated the external environment to control the fiber to generate delay changes. However, this method suffers from problems such as low power of higher-order harmonics in the mode-locked laser and high loss during long-distance transmission. Furthermore, the algorithm for calculating the phase compensation needs further improvement.

[0005] For example, the invention patent with publication number CN119209191A, entitled "Optical Frequency Comb Frequency Stabilization Device and Method," discloses: a first optical filter configured to filter the optical frequency comb to obtain two comb teeth to be locked; an oscillation loop configured to oscillate based on the two comb teeth to be locked, generating an oscillating radio frequency signal at a first angular frequency and an oscillating radio frequency signal at a second angular frequency; and a feedback controller configured to mix the oscillating radio frequency signal at the first angular frequency, the oscillating radio frequency signal at the second angular frequency, and a radio frequency reference signal to extract a time-varying error signal, and output a control signal based on the error signal to lock the frequency of the optical frequency comb. This solution focuses on the frequency stabilization control of the optical frequency comb, and its core is to achieve comb tooth frequency locking through a dual oscillation loop and mixing feedback. However, this technical solution only addresses the frequency stabilization of the optical frequency comb itself and does not involve the monitoring and compensation of time delay jitter in the fiber optic link.

[0006] For example, the invention patent CN115021849B, entitled "Fiber Optic Time Synchronization Device and Method Based on Optoelectronic Combined Time Compensation," discloses a fiber optic time synchronization scheme based on optoelectronic combined time compensation. Its core is to use an optical frequency comb to generate a high-frequency optical microwave signal, achieving time synchronization through dual compensation in the electrical and optical domains. While achieving high-precision measurement of fiber optic delay and significantly improving the compensation accuracy and range by employing a time compensation mechanism combining the electrical and optical domains, while also offering the advantage of rapid response, it suffers from problems such as insufficient synergy in optoelectronic compensation, lack of multi-wavelength dispersion compensation, reliance on high-frequency signals for monitoring accuracy, and limited system architecture flexibility.

[0007] Therefore, it is crucial to utilize multi-wavelength light sources to accurately sense the dispersion and time delay changes in fiber optic links, and to achieve wide-spectrum, high-precision, and fast-response time delay jitter compensation through an efficient feedback mechanism. Summary of the Invention

[0008] In view of this, the main objective of the present invention is to provide an optical frequency comb-stabilized fiber optic link delay jitter system, in order to at least partially solve the above-mentioned technical problems.

[0009] To achieve the above objectives, as a first aspect of the present invention, a frequency comb-stabilized fiber optic link delay jitter system is proposed, comprising: An optical frequency comb is used to provide comb-shaped optical signals and transmit them to the interference unit; An interference unit is used to interfere with the comb-shaped optical signal from the optical frequency comb; A reciprocating correction unit is used to perform reverse isolation and frequency modulation on the interfered optical signal, which is then transmitted to the dual-optical secondary mixing unit after beam splitting; and The dual-optical secondary mixer unit is used to obtain a zero-frequency voltage signal through photoelectric conversion. The zero-frequency voltage signal is then processed by a proportional-integral controller and used as the input voltage signal of a tunable delay line to control the delay jitter of the optical fiber link.

[0010] Based on the above technical solution, it can be seen that the optical frequency comb stabilization fiber optic link delay jitter system of the present invention has at least one of the following beneficial effects compared with the prior art: 1. The dual-optical secondary mixing unit contains two delay self-heterodyne interference units. It uses optical frequency domain signals to more accurately sense the fiber optic link delay jitter. Through photoelectric conversion, it uses two radio frequency signals carrying fiber optic link delay jitter to obtain a zero-frequency voltage signal through a mixer. Compared with the technical problem of traditional delay detection that it is difficult to accurately capture the subtle changes in optical frequency domain signals, this zero-frequency voltage signal serves as the input voltage signal that can coordinate the optical delay line, thereby controlling the fiber optic link delay jitter. 2. Compared with existing technologies, which suffer from insufficient photoelectric compensation coordination, lack of multi-wavelength dispersion compensation, reliance on high-frequency signals for monitoring accuracy, and limited system architecture flexibility, this invention selects different order comb teeth of the optical frequency comb through an optical filter, and obtains the frequency components of different sensing fiber optic link delay jitter by adjusting the filtering parameters of the optical filter. The frequency components can be selected in a more flexible way and with a larger range. 3. The optical path architecture design, including an integrated wavelength division multiplexer, polarization beam splitter, Faraday rotator, acousto-optic frequency shifter, and tunable optical delay line, combined with a dual-optical secondary mixer unit, utilizes an optical frequency comb as a high-precision reference source. Through photoelectric conversion and mixing processing, it accurately extracts time delay jitter information and drives the tunable optical delay line for compensation in real time. Compared with the existing technology, which has the problems of insufficient accuracy in sensing time delay jitter and inability to compensate in real time and effectively, this invention significantly improves the accuracy and real-time performance of time delay jitter control in optical fiber links, and effectively ensures the stability and reliability of optical fiber link signal transmission. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the optical frequency comb stabilization fiber optic link delay jitter system of the present invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0014] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of the invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0015] The inventors discovered that existing technologies suffer from low high-order harmonic power in mode-locked lasers and significant losses during long-distance transmission. Furthermore, the algorithm for calculating phase compensation needs further improvement. Through in-depth research, they found that by using a dual-optical secondary mixer unit containing two delayed self-heterodyne interference units, fiber optic link delay jitter can be more accurately sensed using optical frequency domain signals. Through photoelectric conversion, two radio frequency signals carrying fiber optic link delay jitter are used to obtain a zero-frequency voltage signal via a mixer. This zero-frequency voltage signal, after processing by a proportional-integral controller, serves as the input voltage signal for coordinating the optical delay line, thus controlling fiber optic link delay jitter. Therefore, as... Figure 1 As shown, the inventors have proposed an optical frequency comb-stabilized fiber optic link delay jitter system, comprising: An optical frequency comb is used to provide comb-shaped optical signals and transmit them to an interference unit; the interference unit is used to interfere with the comb-shaped optical signals from the optical frequency comb. A reciprocating correction unit is used for reverse isolation and frequency modulation of the optical signal, which is then transmitted to the dual-optical secondary mixer after beam splitting; and The dual-optical secondary mixer unit is used to obtain a zero-frequency voltage signal through photoelectric conversion. The zero-frequency voltage signal is then processed by a proportional-integral controller and used as the input voltage signal of a tunable delay line to control the delay jitter of the optical fiber link.

[0016] The present invention will be further illustrated below through specific embodiments. It should be noted that the following embodiments are merely illustrative and not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments shown below without inventive effort are within the scope of protection of the embodiments of the present invention.

[0017] Example 1 In this embodiment, further, Figure 1 This is a schematic diagram of the optical frequency comb-stabilized fiber optic link delay jitter system of the present invention; as can be seen from the figure, in this embodiment, the specific structure of the interference unit is as follows: The first coupler is used to combine the optical signal generated by the optical frequency comb with the input signal and then input the input signal into the first wavelength division multiplexer. The first wavelength division multiplexer is used to multiplex the wavelengths of the combined optical signal and output it to the polarization beam splitter. A polarization beam splitter is used to separate the polarization states of an optical signal before outputting the signal; and The second wavelength division multiplexer is used to receive the optical signal after it has been processed by the polarization beam splitter.

[0018] The reciprocating correction unit includes: A Faraday rotator is used to receive optical signals from a second wavelength division multiplexer and isolate reverse optical signals. An acousto-optic frequency shifter is used to perform a first frequency shift on an optical signal, followed by a second frequency shift after reflection by a Faraday rotator. A tunable optical delay line is used to adjust the transmission delay of optical signals; and Fiber optic links are used to carry optical signal transmission and generate time delay jitter.

[0019] The optical signal transmitted through the optical fiber link is split by the second coupler and then transmitted to the dual-optical secondary mixing unit.

[0020] The dual-optical secondary mixing unit includes: Optical filters are used to remove stray wavelengths from the split optical signal. The optical filters employ a programmable WaveShaper to control the parameters of the bandpass filter and select the comb teeth of different orders of optical frequency combs. The optical frequency comb is not an input signal; it serves as a sensing structure within the system. By adjusting the filtering parameters of the optical filter, different orders of optical frequency comb teeth are obtained. These different orders of optical frequency comb teeth are used to sense differences in fiber optic link delay jitter. In the optical frequency comb sensing system, probe signals are used to detect specific frequency components of the fiber optic link delay jitter. The probe signals are essentially single or group frequency signals from the comb teeth output by the optical frequency comb after filtering. The selection of frequency components is flexible and has a wide range.

[0021] Two photodetectors are used to convert optical signals into electrical signals; Two electrical filters are used to filter out noise from the electrical signal output by the photodetector. A mixer is used to mix two electrical signals to obtain a difference frequency signal; and The proportional-integral (PI) controller generates a control signal based on the difference frequency signal and feeds it back to the tunable optical delay line. The PPI controller has Kp=10, Ki=3.5, and Kd=2.6. This design is based on the system's requirement for high-precision, real-time delay jitter control. By optimizing the synergistic effect of the proportional, integral, and derivative components, it achieves accurate compensation for delay jitter in the fiber optic link. The proportional component directly amplifies the error signal, quickly generating a control quantity to reduce delay jitter. Kp=10 shortens the system response time, ensuring timely feedback to real-time changes in delay jitter, such as rapid fluctuations in the fiber optic link caused by environmental disturbances. Simultaneously, considering that the delay jitter in the fiber optic link may change frequently due to factors such as temperature and stress, a high Kp value enhances the system's sensitivity to high-frequency jitter, preventing jitter accumulation. The integral component accumulates historical errors, eliminating the system's steady-state deviation, i.e., residual errors that proportional control cannot completely eliminate. A moderate value of Ki=3.5 ensures error elimination efficiency while avoiding integral saturation problems, such as overshoot caused by excessive control quantity due to prolonged integration. The differential element predicts the trend of error change and applies damping in advance, suppressing system overshoot and enhancing dynamic stability. A value of Kd=2.6 can effectively reduce the risk of oscillation that may be caused by the rapid response of the proportional element, and is especially suitable for tunable optical delay lines that include motors and piezoelectric ceramics.

[0022] The first wavelength division multiplexer is provided with at least two input ports and one output port. The input ports are used to input optical frequency comb signals and input signals, respectively, and the output port is used to output multiplexed optical signals.

[0023] The tunable optical delay line is configured with a motor and a piezoelectric ceramic. The motor has a compensation accuracy on the order of fs, a speed on the order of milliseconds, and a compensation range on the order of nanoseconds. The piezoelectric ceramic (PZT) has a compensation accuracy on the order of sub-fs, a speed on the order of sub-milliseconds, and a range on the order of picoseconds. The two working together can achieve fast, wide-range, and high-precision fiber optic link delay jitter compensation. The motor (millisecond-level response speed) and the piezoelectric ceramic (sub-millisecond response speed) of the tunable optical delay line are matched with parameters of a proportional-integral (PID) controller to achieve collaborative compensation of "wide-range coarse adjustment + high-precision fine adjustment": the voltage signal output by the PID controller controls the motor and the piezoelectric ceramic, and the motor and the piezoelectric ceramic respectively achieve high-precision, fast, and wide-range compensation of the signal. This collaborative mechanism avoids the limitations of a single actuator (such as insufficient motor accuracy or limited range of piezoelectric ceramic), and achieves a balance between efficiency and accuracy through the optimization of PID controller parameters.

[0024] The fiber optic link is set to a length of 1 km, and the Faraday rotator is configured for a round-trip structure. One kilometer of fiber can provide the functionality of two kilometers, while the system feedback compensates for the jitter of the round-trip fiber optic link delay.

[0025] The optical filter selects comb teeth of different orders from the optical frequency comb. Based on the desired order of the optical frequency comb teeth, the upper and lower limit frequencies of the filter are set to achieve the function of a bandpass filter.

[0026] By adjusting the filtering parameters of the optical filter, the frequency components of fiber optic link delay jitter at the corresponding frequency can be obtained. The filtering parameters are set based on the optical frequency comb spectrum information measured by a spectrometer, achieving a frequency shift of twice the acousto-optic frequency shifter between the two optical frequency comb teeth to be filtered out. By controlling the filtering parameters through the optical filter and selecting optical frequency comb teeth of different orders, the filtering range is wider and more flexible compared to traditional optical filters.

[0027] The working principle and process of this invention are as follows: The optical frequency comb is split into two signals by the first coupler. One signal serves as the reference signal, while the other, after passing through a polarization beam splitter, first undergoes a time delay via an optical fiber link, then enters an acousto-optic frequency shifter for frequency shifting. At the far end, it is reflected back by a Faraday rotator mirror, which rotates the polarization direction of the light to ensure the stability of the optical signal transmission in the system. Next, it undergoes frequency shifting again via the acousto-optic frequency shifter, then the optical fiber link, and finally, through the polarization beam splitter, it is coupled to the local signal via the second coupler and filtered by a bandpass filter. The bandpass filter's function is achieved through an optical filter, which performs filtering based on filtering parameters. Each bandpass filter outputs two optical signals of the same order: the reference signal and the two signals shifted by the acousto-optic frequency shifter via the link. Since the frequency shift of the acousto-optic frequency shifter is much smaller than the frequency interval of the comb teeth, two optical frequency comb teeth with a frequency interval twice that of the acousto-optic frequency shifter can be obtained after filtering. Similar to the delay self-heterodyne, the beat frequency of the two optical signals yields an intermediate frequency signal containing phase information. The difference lies in the fact that in the dual-optical double-mixing unit, an additional filter is used to filter out two optical frequency comb teeth with a frequency difference of twice the frequency shift of the acousto-optic frequency shifter. The optical filter functions as two bandpass filters, outputting two sets of optical signals. The passbands of the four optical signals contained in the two sets of optical signals are different, and the order of the filtered optical signal comb teeth is also different. The two optical frequency comb teeth with a frequency difference of twice the frequency shift of the acousto-optic frequency shifter obtain a beat frequency signal after passing through a photodetector. Since the dual-optical double-mixing structure contains two delay self-heterodyne structures, two electrical signals with the same frequency but different phases are obtained. After passing through the mixer, a zero-frequency voltage signal is obtained. This signal is processed by a proportional-integral controller and fed back to the tunable optical delay line in the control fiber optic link to compensate for the time delay jitter in the fiber optic link sensed by the optical frequency comb teeth. The proportional-integral (PI) controller, with parameters Kp=10, Ki=3.5, and Kd=2.6, is designed based on the triple objectives of "fast response, steady-state accuracy, and dynamic stability" for fiber optic link delay jitter control. By optimizing the weights of the proportional, integral, and derivative components, it achieves a comprehensive improvement in femtosecond-level accuracy, sub-millisecond-level response speed, and anti-interference capability. This parameter combination not only adapts to the mechanical characteristics of tunable optical delay lines but also solves the core problems of insufficient accuracy and poor real-time performance in existing technologies through a closed-loop feedback mechanism, providing a highly reliable delay jitter control solution for fields such as fiber optic communication and precision measurement.

[0028] The dual-optical secondary mixer unit of this invention comprises two delay-self-heterodyne interference units. It uses optical frequency domain signals to more accurately sense fiber optic link delay jitter. Through photoelectric conversion, two radio frequency signals carrying fiber optic link delay jitter are used to obtain a zero-frequency voltage signal via a mixer. This zero-frequency voltage signal is processed by a proportional-integral controller and used as the input voltage signal to coordinate the optical delay line, thereby controlling the fiber optic link delay jitter. Different orders of optical frequency combs are selected through an optical filter, and different frequency components for sensing fiber optic link delay jitter are obtained by adjusting the filter parameters. The selection of frequency components is flexible and has a wide range. The optical path architecture design, which integrates a wavelength division multiplexer, polarization beam splitter, Faraday rotator, acousto-optic frequency shifter, and tunable optical delay line, combined with a dual-optical secondary mixer unit, utilizes an optical frequency comb as a high-precision reference source. Through photoelectric conversion and mixing processing, it accurately extracts time delay jitter information and drives the tunable optical delay line for compensation in real time. The stable time delay jitter is on the femtosecond scale, significantly improving the accuracy and real-time performance of time delay jitter control in fiber optic links, and effectively ensuring the stability and reliability of fiber optic link signal transmission. The high-order comb tooth power can meet the phase-locked loop requirements, resulting in higher stability. It is low in cost, offers flexible probe signal frequency selection with a wide range of choices, and high precision.

[0029] The foregoing has described specific embodiments of the present invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0030] In the description of the embodiments of the present invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In the embodiments of the present invention, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in the embodiments of the present invention, as well as the features of the different embodiments or examples.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of embodiments of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of the invention pertain.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An optical frequency comb-stabilized fiber optic link delay jitter system, characterized in that, include: An optical frequency comb is used to provide comb-shaped optical signals and transmit them to the interference unit; An interference unit is used to interfere with the comb-shaped optical signal from the optical frequency comb; The reciprocating correction unit is used to perform reverse isolation and frequency modulation on the interferometric optical signal, which is then transmitted to the dual-optical secondary mixing unit after beam splitting. as well as The dual-optical secondary mixer unit is used to obtain a zero-frequency voltage signal through photoelectric conversion, and the zero-frequency voltage signal is processed by a proportional-integral controller and used as the input voltage signal of the tunable optical delay line to control the delay jitter of the optical fiber link. The dual-optical secondary mixing unit includes an optical filter. The optical filter implements the function of two bandpass filters based on filtering parameters, filtering out two sets of optical signals respectively. The four optical signals contained in the two sets of optical signals have different passbands and different comb tooth orders. Moreover, the two optical frequency comb teeth contained in each set of optical signals differ in frequency interval by twice the frequency shift amount of the acousto-optic frequency shifter.

2. The optical frequency comb-stabilized fiber optic link delay jitter system according to claim 1, characterized in that, The interference unit includes: The first coupler is used to receive the optical signal generated by the optical frequency comb; The first wavelength division multiplexer receives the input signal and the optical signal output from the first coupler, and performs wavelength multiplexing on the optical signal that combines the input signal and outputs it to the polarization beam splitter. A polarization beam splitter is used to separate the polarization states of an optical signal before outputting the signal; and The second wavelength division multiplexer is used to receive the optical signal after it has been processed by the polarization beam splitter.

3. The optical frequency comb-stabilized fiber optic link delay jitter system according to claim 1, characterized in that, The reciprocating correction unit includes: A Faraday rotator is used to receive optical signals from a second wavelength division multiplexer and isolate reverse optical signals. An acousto-optic frequency shifter is used to perform a first frequency shift on an optical signal, followed by a second frequency shift after reflection by a Faraday rotator. A tunable optical delay line is used to adjust the transmission delay of optical signals; and Fiber optic links are used to carry optical signal transmission and generate time delay jitter.

4. The optical frequency comb-stabilized fiber optic link delay jitter system according to claim 3, characterized in that, The optical signal transmitted through the optical fiber link is split by the second coupler and then transmitted to the dual-optical secondary mixing unit.

5. The optical frequency comb-stabilized fiber optic link delay jitter system according to claim 1, characterized in that, The dual-optical secondary mixing unit includes: Optical filters are used to remove stray wavelengths from the split optical signal. Two photodetectors are used to convert optical signals into electrical signals; Two electrical filters are used to filter out noise from the electrical signal output by the photodetector. A mixer is used to mix two electrical signals to obtain a difference frequency signal; and A proportional-integral controller is used to generate a control signal based on the difference frequency signal and feed it back to the tunable optical delay line.

6. The optical frequency comb-stabilized fiber optic link delay jitter system according to claim 2, characterized in that, The first wavelength division multiplexer is provided with at least two input ports and one output port. The input ports are used to input optical frequency comb signals and input signals, respectively, and the output port is used to output multiplexed optical signals.

7. The optical frequency comb-stabilized fiber optic link delay jitter system according to claim 3, characterized in that, The tunable optical delay line is configured with a motor and piezoelectric ceramics.

8. The optical frequency comb-stabilized fiber optic link delay jitter system according to claim 3, characterized in that, The length of the optical fiber link is set to 1 km, and the Faraday rotator is configured as a round-trip structure.

9. The optical frequency comb-stabilized fiber optic link delay jitter system according to claim 5, characterized in that, By adjusting the filtering parameters of the optical filter, the frequency components of the fiber optic link delay jitter at the corresponding frequency can be obtained.

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