Optical modulation link control method, device and system

Abstract

The invention discloses an optical modulation link control method, device and system, and the method comprises the steps: transmitting two paths of optical carrier signals to a polarized light coupling and delay module in the forward direction through corresponding optical circulators, carrying out the coupling and delay control of the two paths of signals, and outputting two paths of modulated light with the polarization planes kept orthogonal; the modulated light enters the Faraday optical rotation reflection module, and is reflected to form two paths of reflected light signals which are reversely transmitted, the two paths of reflected light signals are transmitted back to the polarized light coupling and delay module for secondary delay and partial wave control, and two paths of independent reflected light signals are output; the two paths of independent reflected light signals are reversely incident to a photoelectric detector through corresponding optical circulators respectively, and the photoelectric detector performs photoelectric conversion and signal amplification on the two paths of reflected light signals respectively and outputs two paths of delay microwave frequency discrimination signals for radio-over-fiber phase noise measurement. According to the invention, time synchronization of two paths of delay microwave frequency discrimination signals for phase noise measurement is realized, and the signals are independent and low in crosstalk.

Description

A method, apparatus and system for controlling an optical modulation link. Technical Field

[0001] This invention relates to the field of phase noise detection, and more particularly to an optical modulation link control method, apparatus, and system. Background Technology

[0002] This section is intended to provide background or context for the embodiments of this application set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0003] High-frequency oscillator phase noise detection techniques mainly include phase-locked loop (PLL) methods and frequency discrimination methods based on optical carrier technology. The PLL method, also known as the dual-source method, utilizes double-balanced mixing and PLL technology to lock the output signals of the reference oscillator and the source under test (SUT) in orthogonal phase, using voltage fluctuations during phase quadrature to detect phase noise. The frequency discrimination method, also known as the single-source method, uses signal delay and mixing techniques to convert oscillator frequency fluctuations into phase fluctuations, achieving phase noise measurement. The limitations of PLL phase noise measurement systems are mainly reflected in the following two aspects: First, when measuring high-frequency oscillators, the loop gain range is wide when the frequency difference between the SUT and the reference oscillator after mixing is tens of megahertz, making design difficult. Second, a reference oscillator of the same frequency is required. Test instruments based on the PLL method can no longer meet the phase noise testing requirements of various new types of oscillators. Summary of the Invention

[0004] One objective of this application is to provide an optical modulation link control method for controlling the modulation and delay of optical radio. Another objective of this application is to provide an optical modulation link control device. A further objective of this application is to provide an optical modulation link control system.

[0005] To achieve the above objectives, this application discloses an optical modulation link control method, comprising: two optical carrier signals being transmitted forward through corresponding optical circulators to a polarization coupling and delay module, where the two signals are coupled and delayed to output two modulated lights with orthogonal polarization planes; the two modulated lights being incident on a Faraday rotation reflection module, where they are reflected to form two reflected light signals transmitted in opposite directions, and the two reflected light signals being transmitted back to the polarization coupling and delay module for secondary delay and wavelength division control to output two independent reflected light signals; and the two independent reflected light signals being incident in opposite directions through corresponding optical circulators to a photodetector, where the photodetector performs photoelectric conversion and signal amplification on the two reflected light signals respectively, and outputs two delayed microwave frequency discrimination signals for optical radio phase noise measurement.

[0006] Optionally, before the two modulated optical carrier signals are transmitted forward through their respective optical circulators to the polarization coupling and delay module, the method further includes: the dual-wavelength light source outputs two optical signals, which are transmitted to two identical modulation modules. The two modulation modules process the input optical signals and output two optical carrier signals with orthogonal polarization planes.

[0007] Optionally, the two modulation modules respectively process the input optical signal by: the polarization controller in the modulation module receiving the optical signal, adjusting the polarization state of the optical signal, and outputting a polarization-stable optical signal; the polarization-stable optical signal being transmitted to the reverse isolator in the modulation module, and after the reverse isolator suppresses the reverse reflected light interference, an optical signal without reverse interference is output; the optical signal without reverse interference being transmitted to the modulator in the modulation module, and the modulator performing microwave modulation on the optical signal to output an optical carrier signal.

[0008] Optionally, the coupling and delay control of the two signals includes: the two optical carrier signals respectively enter the polarization optocoupler in the polarization coupling and delay module, and the two signals are coupled through the polarization optocoupler; the coupled signals are transmitted to the single-mode fiber delay array in the polarization coupling and delay module, and the single-mode fiber delay array performs a delay of a preset time to output two modulated lights with orthogonal polarization planes.

[0009] Optionally, the two reflected light signals that are transmitted in opposite directions after reflection include: the two modulated lights are respectively incident on two Faraday rotator mirrors in the Faraday rotator reflection module; the Faraday rotator mirrors reflect the incident modulated light, and at the same time rotate the polarization plane of the reflected light by 90° through the built-in Faraday rotator; the polarization planes of the two reflected lights are controlled to remain orthogonal to each other, forming two reflected light signals that are transmitted in opposite directions.

[0010] Optionally, the polarization coupling and delay module performs secondary delay and wavelength division control as follows: the two reflected light signals are transmitted back to the single-mode fiber delay array, and the single-mode fiber delay array performs secondary delay processing for a preset duration; the two signals after secondary delay are transmitted to the polarization optocoupler, and the polarization optocoupler performs wavelength division processing to output two independent reflected light signals.

[0011] Optionally, the two independent reflected light signals are respectively incident on the photodetector in the opposite direction through the corresponding optical circulators, including: the two independent reflected light signals are respectively incident on the reflected signal input end of the corresponding optical circulator; the optical circulator performs direction filtering on the reflected light signals, so that the reflected light signals are transmitted along a preset reverse transmission path, and are emitted from the detector output end of the optical circulator and incident on the corresponding photodetector.

[0012] Optionally, the photodetector performs photoelectric conversion and signal amplification on the two reflected light signals respectively, including: the photoelectric conversion unit of the photodetector receives the reflected light signal and converts the light signal into an electrical signal; the electrical signal is transmitted to the amplification unit of the photodetector, and linearly amplified by the amplification unit to output a delayed microwave frequency discrimination signal that meets the preset amplitude requirements.

[0013] Another aspect of this application discloses an optical modulation link control device, characterized in that the device comprises: a control module: two optical carrier signals are respectively transmitted forward through corresponding optical circulators to a polarization coupling and delay module, which performs coupling and delay control on the two signals and outputs two modulated lights with orthogonal polarization planes; a reflection module: the two modulated lights are incident on a Faraday rotation reflection module, and after reflection, two reflected light signals are formed and transmitted in opposite directions. The two reflected light signals are transmitted back to the polarization coupling and delay module for secondary delay and wavelength division control, and output two independent reflected light signals; a photoelectric conversion module: the two independent reflected light signals are respectively incident in opposite directions through corresponding optical circulators to a photodetector, which performs photoelectric conversion and signal amplification on the two reflected light signals, and outputs two delayed microwave frequency discrimination signals.

[0014] In another aspect, this application discloses an optical modulation link control system, the system including the optical modulation link control device as described above.

[0015] The beneficial effects of this application are as follows: This application discloses an optical modulation link control method, which couples two optical carrier signals through a polarization optical coupling and delay module, realizing the processing of the two signals in the same module and the same transmission link. Through the direction filtering function of the optical circulator, the forward optical carrier is transmitted only to the polarization optical coupling and delay module, and the reverse reflected light is transmitted only to the photodetector, eliminating the interference of the reverse signal on the modulation module and the light source. The reflected light is transmitted back to the polarization optical coupling and delay module for secondary delay and wavelength division control, so that the two independent reflected light signals are time-synchronized and the signals are independent. Attached Figure Description

[0016] 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 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. In the accompanying drawings: Figure 1 shows a flowchart of a specific embodiment of the optical modulation link control method of this application; Figure 2 shows a flowchart of S010-S030 of a specific embodiment of the optical modulation link control method of this application; Figure 3 shows a flowchart of S110-S120 of a specific embodiment of the optical modulation link control method of this application; Figure 4 shows a flowchart of S210-S230 of a specific embodiment of the optical modulation link control method of this application; Figure 5 shows a flowchart of S240-S250 of a specific embodiment of the optical modulation link control method of this application; Figure 6 shows a flowchart of S310-S320 of a specific embodiment of the optical modulation link control method of this application; Figure 7 shows a flowchart of S330-S340 of a specific embodiment of the optical modulation link control method of this application; Figure 8 shows a structural schematic diagram of a specific example of the optical modulation link control method of this application; Figure 9 shows a structural schematic diagram of an optical modulation link control device of this application; Figure 10 shows a structural schematic diagram of a computer programmable logic device used to implement the embodiments of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B; "and / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0018] It should be understood that the terms "first," "second," etc., in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "include" and "have," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or programmable logic device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or programmable logic devices.

[0019] References to embodiments in this application mean that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0020] In order to solve at least one of the problems existing in the prior art, according to one aspect of this application, as shown in FIG1, this embodiment discloses an optical modulation link control method, the method comprising: S100: two optical carrier signals are respectively transmitted in the forward direction to a polarization optical coupling and delay module through corresponding optical circulators, the two signals are coupled and delayed to control the coupling, and the two modulation lights with orthogonal polarization planes are output.

[0021] Specifically, two optical carrier signals are transmitted forward through corresponding optical circulators to a polarization coupling and delay module. The two signals are coupled and delayed, outputting two modulated beams with orthogonal polarization planes. These modulated beams are then incident on a Faraday rotation reflection module, where they are reflected to form two reverse-transmitted reflected light signals. These reflected light signals are then fed back to the polarization coupling and delay module for secondary delay and wavelength division control, outputting two independent reflected light signals. These independent reflected light signals are then incident backward through corresponding optical circulators to a photodetector. The photodetector performs photoelectric conversion and signal amplification on the two reflected light signals, outputting two delayed microwave frequency discrimination signals for optical radio phase noise measurement. The optical carrier signal is an optical signal carrying a microwave signal. In the preceding signal processing stage, the microwave signal is loaded onto the optical signal to obtain the optical carrier signal. The optical carrier signal utilizes the low-loss and high-bandwidth characteristics of the optical signal to achieve long-distance, high-quality transmission of the microwave signal, providing a stable signal carrier for subsequent phase noise measurement. An optical circulator is an optical device with directional transmission characteristics. Based on optical non-reciprocity, it only allows optical signals to propagate along a preset forward path, blocking reverse-transmitting optical signals to prevent crosstalk from the reverse signal to the preceding module and ensuring the stability of the forward transmission signal. The optical circulator can adopt a three-port or four-port structure, and this application is not limited to this.

[0022] S200: The two modulated lights are incident on the Faraday rotation reflection module. After reflection, they form two reflected light signals that are transmitted in opposite directions. The two reflected light signals are transmitted back to the polarization coupling and delay module for secondary delay and wavelength division control, and output two independent reflected light signals.

[0023] Specifically, the polarization coupling and delay module is a component that enables multiplexed transmission and time synchronization of two signals. Coupling control utilizes the polarization characteristics of light to combine two optical signals with orthogonal polarization planes into the same optical fiber for transmission, reducing the number of transmission links and lowering link loss. Delay control adjusts the length of the transmission path within the module to achieve a preset synchronization state for the transmission time of the two signals. The delay parameters can be determined based on the signal time difference requirements of subsequent phase noise measurements. By acquiring the transmission times of the two signals and comparing them with the preset delay value, the module parameters are adjusted to achieve the desired delay. It should be noted that maintaining orthogonality between the polarization planes of the two modulated lights is crucial to avoiding crosstalk during coupled transmission.

[0024] S300: The two independent reflected light signals are respectively incident on the photodetector through the corresponding optical circulator. The photodetector performs photoelectric conversion and signal amplification on the two reflected light signals respectively, and outputs two delayed microwave frequency discrimination signals for optical radio phase noise measurement.

[0025] Specifically, the Faraday rotation reflection module functions to reflect and rotate the polarization plane of an optical signal. Its working principle utilizes the Faraday rotation effect, causing the polarization plane of the incident light to rotate by a fixed angle during reflection, while the two reflected beams maintain orthogonal polarization planes. The reflected light needs to be transmitted back to the photodetector via reverse propagation. The polarization plane rotation ensures that the reflected light can still be recognized and separated by subsequent modules during this return journey, preventing confusion with the forward transmission signal. The photodetector converts the optical signal into an electrical signal and amplifies it. Photoelectric conversion is based on the photoelectric effect; when reflected light enters the photoelectric conversion unit of the detector, a weak electrical signal proportional to the light intensity is generated. Signal amplification is achieved through a linear amplification circuit, which amplifies the weak electrical signal to the amplitude requirements of subsequent phase noise measurement processing. The amplification factor can be adjusted according to the intensity of the input optical signal and the amplitude requirements of subsequent processing.

[0026] It should be noted that the final output delayed microwave discrimination signal is the input signal for optical radio phase noise measurement. It contains the phase information of the microwave signal under test. By performing subsequent orthogonal phase detection and cross-correlation operations on the two signals, the phase noise characteristics of the signal under test can be extracted. If this signal is missing or of poor quality, with significant noise and phase deviation, it will directly lead to a decrease in the accuracy of the phase noise measurement results or even measurement failure. This application is not limited to this; as long as the signal can accurately reflect the phase information of the signal under test, it can be used for subsequent measurements.

[0027] In an optional implementation, before the two modulated optical carrier signals are transmitted forward through their respective optical circulators to the polarization coupling and delay module, the following further step is taken: S000: The dual-wavelength light source outputs two optical signals, which are transmitted to two modulation modules with identical structures. The two modulation modules process the input optical signals and output two optical carrier signals with orthogonal polarization planes.

[0028] A dual-wavelength light source is a device that generates two distinguishable optical signals to prevent crosstalk between the two signals due to their identical wavelengths during subsequent transmission and coupling. Its working principle involves an internal laser generator that outputs two continuous optical signals of different wavelengths. The difference between the two wavelengths must be such that subsequent modules can effectively distinguish and process them. For example, the wavelength selection of a dual-wavelength light source can be adjusted based on actual conditions such as transmission distance and link loss, as long as the two wavelengths do not interfere with each other.

[0029] The use of two identical modulation modules ensures consistency in the processing of the two optical signals, preventing amplitude and phase deviations in the output optical carrier signals due to differences in module structure, which would affect the accuracy of subsequent phase noise measurements. Their function is to process the raw optical signals output from the dual-wavelength light source, ensuring the processed signals possess orthogonal polarization characteristics and meet subsequent transmission requirements. It's important to note that identical structure refers not only to identical hardware components but also to consistent operating parameter settings, guaranteeing complete equivalence in the processing conditions of the two signals. The modulation module's processing of the optical signal is crucial in converting the raw signal into a compliant optical carrier signal. This processing enables polarization control, interference suppression, and microwave modulation, ultimately resulting in two optical carrier signals with orthogonal polarization planes. The raw optical signals output from the dual-wavelength light source typically lack a stable polarization state and are susceptible to interference from back-reflected light. Furthermore, they lack microwave signal information, making them unsuitable for direct use in subsequent link transmission and phase noise measurements; therefore, processing by the modulation module is necessary.

[0030] In an optional implementation, as shown in FIG2, the two modulation modules respectively process the input optical signal including: S010: the polarization controller in the modulation module receives the optical signal, adjusts the polarization state of the optical signal, and outputs an optical signal with a stable polarization state.

[0031] In this embodiment, the two modulation modules process the input optical signal. This processing is a process of gradually optimizing the characteristics of the optical signal, specifically including: the polarization controller in the modulation module receives the optical signal, adjusts the polarization state of the optical signal, and outputs a polarization-stable optical signal; the polarization-stable optical signal is transmitted to the reverse isolator in the modulation module, and after the reverse isolator suppresses the back-reflected light interference, an optical signal without back-reflection interference is output; the optical signal without back-reflection interference is transmitted to the modulator in the modulation module, and the modulator performs microwave modulation on the optical signal to output an optical carrier signal.

[0032] It should be noted that the polarization controller is a component that adjusts the polarization state of the optical signal. The polarization state of the original optical signal output from a dual-wavelength light source is usually unstable, and a stable polarization state is a prerequisite for achieving orthogonal polarization of the two signals and reducing crosstalk. Its working principle is to collect the real-time polarization state parameters of the optical signal through an internal adjustable optical element, compare it with the preset target polarization state parameters, and then adjust the angle or phase of the optical element to make the polarization state of the output optical signal reach a stable state. For example, the adjustment method of the polarization controller can be divided into manual adjustment and automatic adjustment. The automatic adjustment method can respond more promptly to polarization drift caused by environmental changes. This application is not limited to this, as long as a stable polarization state output can be achieved.

[0033] S020: The polarization-stable optical signal is transmitted to the reverse isolator in the modulation module. After the reverse isolator suppresses the reverse reflected light interference, an optical signal without reverse interference is output.

[0034] The purpose of a reverse isolator is to address the potential for back-reflected light in the optical link. This back-reflected light can interfere with preceding light sources or polarization controllers, leading to a degraded optical signal quality. Its working principle utilizes optical non-reciprocity, allowing only the optical signal to propagate in the forward direction while blocking or absorbing the back-reflected light, thus suppressing back-reflected light interference. It's important to note that the isolation level of the reverse isolator is a key performance indicator. Higher isolation levels result in better suppression of back-reflected light and better ensure the stability of the forward optical signal. Insufficient isolation levels mean that back-reflected light can still interfere with preceding modules, affecting subsequent modulation processes.

[0035] S030: The optical signal without reverse interference is transmitted to the modulator in the modulation module, and the modulator performs microwave modulation on the optical signal to output an optical carrier signal.

[0036] The function of a modulator is to load a microwave signal onto an optical signal to generate an optical carrier signal. The original optical signal serves only as a transmission carrier and lacks information about the microwave signal to be measured. Modulation is necessary to map the amplitude, phase, or frequency information of the microwave signal onto the optical signal. Its working principle is to control the refractive index or transmittance of the internal optical medium by the microwave signal to be loaded, thereby changing the corresponding characteristics of the optical signal and achieving modulation from microwave to optical signal. For example, the modulator can be a phase modulator, amplitude modulator, etc. The specific selection needs to be determined based on the modulation requirements of the optical carrier signal for subsequent phase noise measurements; this application is not limited to this.

[0037] The optical carrier signal output after the above three processing steps has a stable polarization state, eliminates reverse interference, and carries the microwave signal information to be tested, which fully meets the requirements of subsequent optical circulator transmission, polarization optical coupling and delay module processing. If any of these processing steps are missing, the optical signal may have problems such as unstable polarization state, reverse interference or no microwave information, and cannot be used as an effective signal carrier for subsequent links.

[0038] In an optional implementation, as shown in FIG3, the coupling and delay control of the two signals includes: S110: the two optical carrier signals respectively enter the polarization optical optocoupler in the polarization optical coupling and delay module, and the two signals are coupled through the polarization optical optocoupler.

[0039] In this embodiment, the coupling and delay control of the two signals is a function of the polarization coupling and delay module. This process aims to achieve multiplexing and time synchronization of the two signals. Specifically, it includes: the two optical carrier signals respectively enter the polarization optocoupler in the polarization coupling and delay module, and the two signals are coupled through the polarization optocoupler; the coupled signal is transmitted to the single-mode fiber delay array in the polarization coupling and delay module, and the single-mode fiber delay array performs a delay of a preset time to output two modulated lights with orthogonal polarization planes.

[0040] It should be noted that the polarization-coupled optical device (PSC) is a key component for coupling two signals. To reduce the number of transmission links and lower link loss, it combines two independently transmitted optical signals into a single optical fiber. Its working principle utilizes the polarization-splitting and combining characteristics of light to identify the orthogonal polarization states of the two optical carrier signals and merge them into the same transmission path, while ensuring that the polarization states of the two signals do not change and there is no significant crosstalk during coupling. The coupling efficiency of the PSC can be adjusted according to the actual link loss requirements, as long as the strength of the two coupled signals meets the needs of subsequent processing; this application is not limited to this.

[0041] S120: The coupled signal is transmitted to the single-mode fiber delay array in the polarization coupling and delay module. After being delayed for a preset duration by the single-mode fiber delay array, the modulated light with two orthogonal polarization planes is output.

[0042] The single-mode fiber delay array is designed to address the time difference that may exist between two optical carrier signals before they reach the coupler due to variations in transmission path length and module processing time. Subsequent phase noise measurements require synchronization between the two signals, necessitating delay processing to eliminate this time difference. Its working principle involves multiple segments of single-mode fiber of varying lengths. By selecting different fiber paths, the transmission time of the optical signals is adjusted to achieve a preset delay. In practical applications, the time parameters of the coupled signal are collected and compared with the preset delay value, allowing for the selection of an appropriate fiber path to adjust the delay.

[0043] It should be noted that the preset duration in the preset delay processing needs to be determined based on the actual time difference between the two signals. If the time difference is zero, no additional delay is needed. If there is a time difference, the delay duration must be equal to the time difference to ensure that the two signals are synchronized when they are output. For example, if the signals after the delay processing still have a time difference, the two signals will not correspond in the subsequent reflection and demultiplexing stages, affecting the quality of the delayed microwave frequency discrimination signal after photoelectric conversion, and thus reducing the accuracy of phase noise measurement. This application is not limited to this; as long as the two signals can be synchronized in time, it is acceptable.

[0044] In addition, the two output modulated lights with orthogonal polarization planes must maintain a stable orthogonal state. This is a prerequisite for the accurate reflection by the subsequent Faraday rotation reflection module, polarization coupling, and secondary wavelength division by the delay module. If the orthogonal state is interrupted during the delay process, it may cause crosstalk between the two signals, making it impossible to achieve subsequent independent processing. Therefore, the single-mode fiber delay array must have polarization preservation capability to avoid changing the polarization state of the optical signal during the delay process.

[0045] In an optional implementation, as shown in FIG4, the two reflected light signals that are transmitted in the opposite direction after reflection include: S210: the two modulated lights are respectively incident on two Faraday rotator reflectors in the Faraday rotator reflection module.

[0046] In this embodiment, the two reflected light signals that are transmitted in opposite directions after reflection are the functional output of the Faraday rotation reflection module. This process lays the foundation for subsequent signal return by reflecting and adjusting the polarization state of the modulated light. Specifically, it includes: the two modulated lights are respectively incident on two Faraday rotation mirrors in the Faraday rotation reflection module; the Faraday rotation mirrors reflect the incident modulated light, and at the same time rotate the polarization plane of the reflected light by 90° through the built-in Faraday rotator; the polarization planes of the two reflected lights are controlled to remain orthogonal to each other, forming two reflected light signals that are transmitted in opposite directions.

[0047] It should be noted that the Faraday rotator is a device that integrates reflection and polarization rotation functions. In order to achieve the reflection of light signals while adjusting the polarization state, so that the reflected light can be accurately identified and processed by subsequent modules and avoid confusion with the modulated light transmitted in the forward direction, it consists of a reflector and a built-in Faraday rotator. The reflector is responsible for reflecting the incident modulated light back to the original transmission path, while the Faraday rotator is responsible for changing the polarization state of the reflected light.

[0048] S220: The Faraday rotator reflects the incident modulated light and simultaneously rotates the polarization plane of the reflected light by 90° through the built-in Faraday rotator.

[0049] Specifically, the built-in Faraday rotator operates based on the Faraday effect. Under the influence of an external magnetic field, the polarization plane of light rotates, and the direction of rotation is independent of the light's propagation direction. When modulated light is incident on the Faraday rotator, the polarization plane rotates by a certain angle. After being reflected by a mirror, the light passes through the Faraday rotator again, and the polarization plane rotates another 90°, ultimately achieving the effect that the polarization plane of the reflected light is rotated 90° relative to the incident modulated light. It should be noted that the 90° rotation is designed to clearly distinguish the polarization state of the reflected light from that of the forward propagation light, facilitating subsequent polarization coupling and delay modules for wavelength division processing. If the rotation angle does not meet the requirements, wavelength division may be difficult, affecting the independence of the two reflected light signals.

[0050] S230: Controls the polarization planes of the two reflected lights to remain orthogonal to each other, forming two reflected light signals that are transmitted in opposite directions.

[0051] Specifically, maintaining the orthogonality of the polarization planes of the two reflected beams is crucial to ensuring no crosstalk between the two signals after subsequent wavelength division. The control principle is based on the fact that the two incident modulated beams inherently possess orthogonal polarization characteristics, and the Faraday rotator mirror rotates the polarization planes of the two modulated beams at the same angle. Therefore, the rotated reflected beams maintain their orthogonal polarization. For example, if the orthogonality of the two reflected beams is interrupted, during subsequent wavelength division back to the polarization coupling and delay module, one signal may be mixed with components of the other, leading to a decrease in the quality of the reflected light signal and consequently affecting the accuracy of the delayed microwave frequency discrimination signal after photoelectric conversion. This application is not limited to this; as long as the orthogonality of the two reflected beams can be guaranteed, it is acceptable.

[0052] Furthermore, the reverse-transmitted reflected light signal travels in the opposite direction to the forward-transmitted modulated light. Its function is to send the reflected and polarized signal back to the polarization coupling and delay module for secondary delay and wavelength division, providing a signal source for subsequent photoelectric conversion. It should be noted that the intensity of the reflected light signal must meet the requirements of subsequent processing. Therefore, the Faraday rotator mirror must have a high reflectivity to reduce signal energy loss during reflection and avoid subsequent processing failure due to a weak signal.

[0053] In an optional implementation, as shown in Figure 5, the polarization coupling and delay module performs secondary delay and wavelength division control as follows: S240: The two reflected light signals are transmitted back to the single-mode fiber delay array and undergo secondary delay processing for a preset duration through the single-mode fiber delay array.

[0054] In this embodiment, the polarization coupling and delay module performs secondary delay and wavelength division control to optimize the returned reflected light signals and output independent, synchronous signals. Specifically, this includes: the two reflected light signals are returned to the single-mode fiber delay array, and then subjected to a secondary delay of a preset duration by the single-mode fiber delay array; the two signals after the secondary delay are transmitted to the polarization optocoupler, and then subjected to wavelength division processing by the polarization optocoupler to output two independent reflected light signals.

[0055] It should be noted that the secondary delay processing arises because the reflected light signal may experience a time difference during reverse transmission due to factors such as changes in transmission path length and environmental interference. Subsequent photoelectric conversion and phase noise measurement require the two signals to remain synchronized; therefore, a secondary delay is needed to eliminate this time difference. Its working principle is the same as the first delay processing, both adjusting the signal transmission time using a single-mode fiber delay array. The preset duration needs to be determined based on the actual time difference between the two reflected light signals, ensuring time synchronization after the secondary delay. For example, without secondary delay processing, the time difference between the two reflected light signals would cause a phase deviation in the delayed microwave frequency discrimination signal output by the photodetector, affecting the accuracy of subsequent phase noise measurements. This application is not limited to this; any method that achieves time synchronization of the two signals is acceptable.

[0056] S250: The two signals after the second delay are transmitted to the polarization optocoupler, which performs wave splitting processing to output two independent reflected light signals.

[0057] Specifically, wavelength division multiplexing (WDM) is another function of polarization-coupled optical devices. The reflected light signal remains coupled during transmission, but the two signals need to be transmitted separately to their respective photodetectors for independent processing. Therefore, WDM separates the coupled signals. Its working principle utilizes the polarization characteristics of light to identify the orthogonal polarization states of the two reflected light signals, guiding them to different output ports to achieve independent output. It's important to note that the separation degree of WDM is a key indicator. Higher separation results in less crosstalk between the two signals and better quality independent reflected light signals. Insufficient separation leads to mutual interference between the two signals, causing clutter in the subsequent photoelectric conversion signal and affecting the accuracy of the delayed microwave frequency discrimination signal.

[0058] It should be noted that the two independent reflected light signals output must simultaneously meet the conditions of time synchronization and no crosstalk. These two conditions are crucial for the subsequent accurate conversion and amplification of signals by the photodetector, as well as the accuracy of the final phase noise measurement. If the signals are not independent or are not synchronized, it will directly affect the control effect of the entire optical modulation link, thereby causing the phase noise measurement results to fail.

[0059] In an optional implementation, as shown in FIG6, the two independent reflected light signals are respectively incident on the photodetector in the opposite direction through the corresponding optical circulator, including: S310: the two independent reflected light signals are respectively incident on the reflected signal input terminal of the corresponding optical circulator.

[0060] In this embodiment, the reverse transmission step of the optical circulator is crucial for the directional transmission of the reflected light signal to the photodetector. It is used to avoid crosstalk between the reflected light signal and the preceding module, ensuring that the signal accurately reaches the target device. Specifically, the two independent reflected light signals are respectively incident on the reflected signal input terminal of the corresponding optical circulator; the optical circulator performs directional filtering on the reflected light signal, causing the reflected light signal to be transmitted along a preset reverse transmission path, exiting from the detector output terminal of the optical circulator, and incident on the corresponding photodetector.

[0061] It should be noted that the reflected signal input port is a dedicated input port for the reflected optical signal transmitted in the reverse direction within the optical circulator. The optical circulator has directional transmission characteristics; signals in different transmission directions must be input from different ports to ensure the signals travel along a predetermined path. This port design prevents the reflected optical signal from sharing the same input port with the forward-transmitting optical carrier signal, thus avoiding crosstalk between the two signals within the circulator. For example, the number of ports on the optical circulator can be selected according to actual link requirements, as long as it provides independent input and output ports for both forward and reverse signals; this application is not limited to this.

[0062] S320: The optical circulator performs directional filtering on the reflected light signal, causing the reflected light signal to be transmitted along a preset reverse transmission path, emitted from the detector output end of the optical circulator, and incident on the corresponding photodetector.

[0063] Specifically, direction filtering is a function of the optical circulator. Its operating principle is based on optical non-reciprocity. The optical structure inside the circulator identifies the transmission direction of the incident signal, allowing only the signal to travel along a preset unidirectional path and blocking transmission in other directions. For reflected light signals, the direction filtering function guides them to a preset reverse transmission path, preventing the signal from being transmitted to the output port of the forward transmission, thus preventing crosstalk to preceding modules. The preset reverse transmission path refers to the transmission path planned inside the optical circulator for reflected light signals. This path starts at the reflected signal input end and ends at the detector output end. The purpose of this path is to allow the reflected light signal to be directly transmitted to the photodetector, reducing losses and interference in intermediate transmission stages. It should be noted that the loss of the preset reverse transmission path must be controlled within an acceptable range. If the loss is too high, it will lead to a decrease in the intensity of the reflected light signal, affecting the subsequent photoelectric conversion effect. The detector output is a dedicated output port for connecting the optical circulator to the photodetector. Its function is to output the direction-filtered reflected light signal to the corresponding photodetector, so that each reflected light signal can be matched with the corresponding detector. For example, if there is a deviation in the connection between the detector output and the photodetector, the reflected light signal will not be able to be incident on the detector normally, and thus the delayed microwave frequency discrimination signal cannot be generated, affecting the phase noise measurement. This application is not limited to this, as long as the accurate transmission of the signal from the circulator to the detector can be achieved.

[0064] It should be noted that the reverse transmission function of the optical circulator is the key to the signal flow control of the entire optical modulation link. It enables the independent transmission of forward and reverse signals, avoiding mutual interference and ensuring the stable operation and signal quality of the entire link. Without this function, the reflected light signal may crosstalk to the light source, modulation module and other upstream components, resulting in signal chaos in the entire link and the inability to output the delayed microwave frequency discrimination signal for phase noise measurement.

[0065] In an optional implementation, as shown in FIG7, the photodetector performs photoelectric conversion and signal amplification on the two reflected light signals respectively, including: S330: The photoelectric conversion unit of the photodetector receives the reflected light signal and converts the light signal into an electrical signal.

[0066] In this embodiment, the photodetector converts the reflected light signal into an electrical signal and amplifies it to generate a delayed microwave frequency discrimination signal that meets the requirements of subsequent phase noise measurement. The specific process is as follows: the photoelectric conversion unit of the photodetector receives the reflected light signal and converts the light signal into an electrical signal; the electrical signal is transmitted to the amplification unit of the photodetector, and is linearly amplified by the amplification unit to output a delayed microwave frequency discrimination signal that meets the preset amplitude requirements.

[0067] It should be noted that the photoelectric conversion unit is the component that realizes the conversion of photoelectric signals. Subsequent phase noise measurements are usually based on electrical signal processing, so it is necessary to convert the optical signal into an electrical signal. Its working principle is based on the photoelectric effect, such as the photovoltaic effect of a photodiode. When the reflected light signal is incident on the photosensitive material of the photoelectric conversion unit, the photosensitive material absorbs photon energy, excites electron transitions, and generates a weak electrical signal proportional to the intensity of the light signal. For example, the type of photoelectric conversion unit can be selected according to parameters such as the wavelength and intensity of the reflected light signal, as long as efficient photoelectric conversion can be achieved; this application is not limited to this.

[0068] S340: The electrical signal is transmitted to the amplification unit of the photodetector, and is linearly amplified by the amplification unit to output a delayed microwave frequency discrimination signal that meets the preset amplitude requirements.

[0069] Specifically, the amplification unit is designed because the electrical signal output from the photoelectric conversion unit is typically very weak and cannot meet the amplitude requirements of subsequent phase noise measurement processing. Therefore, amplification is necessary to increase the signal amplitude. Its working principle is to use a linear amplifier circuit to linearly amplify the weak electrical signal, ensuring that the phase information of the signal is not distorted during amplification. If nonlinear distortion exists, it will cause changes in the phase information of the electrical signal, thus affecting the accuracy of subsequent phase noise measurements. The preset amplitude requirement refers to the amplified electrical signal amplitude meeting the input requirements of the subsequent processing module. This requirement is usually determined by the performance parameters of the subsequent module. In practical applications, the amplitude of the electrical signal output from the amplification unit can be collected and compared with the preset amplitude to adjust the amplification factor of the amplification unit. It should be noted that a larger amplification factor is not always better. If the amplification factor is too large, it may cause saturation distortion of the electrical signal, interrupting the phase information of the signal; if the amplification factor is too small, it will not meet the requirements of subsequent processing. Therefore, an appropriate amplification factor must be selected based on the actual situation. The delayed microwave discrimination signal is the final output of the photodetector, containing the phase information of the microwave signal under test and serving as the input for subsequent optical radio phase noise measurements. The quality of this signal directly determines the accuracy of the phase noise measurement; therefore, the photoelectric conversion efficiency and linearity of the amplification unit of the photodetector are crucial performance indicators. For example, if the signal-to-noise ratio of the delayed microwave discrimination signal is too low, the phase noise information cannot be accurately extracted during subsequent measurements. Poor amplitude consistency between the two signals will affect the effectiveness of cross-correlation calculations. This application is not limited to these limitations; as long as the signal accurately reflects the phase characteristics of the signal under test, it can be used for subsequent measurements.

[0070] In a specific example, as shown in Figure 8, the dual-wavelength light source 1 outputs two optical carrier signals, a and b, which are connected to modulation modules 2A and 2B respectively via polarization-maintaining fibers. Modulation modules 2A and 2B have identical internal structures, consisting of a polarization controller, a reverse isolator, and a modulator, respectively. Modulation modules 2A and 2B modulate the input optical signals a and b after polarization and reverse isolation control, respectively, to output optical carrier signals. The modulated optical carrier signals are then reverse isolated by optical circulators 3A and 3B, and output as two signals, a2 and b2 respectively. Two orthogonally polarized modulated lights are input to the polarization-coupled delay module 4 for delay control. After being delayed by the fiber delay array inside the polarization-coupled delay module 4, two orthogonally polarized modulated lights a3 and b3 are output. a3 and b3 are incident on the Faraday rotation reflection module 5 and, after passing through the two Faraday rotation mirrors inside, the polarization plane of the reflected wave of a3 is rotated by 90° to form the reverse-transmitted a4, and the polarization plane of the reflected wave of b3 is rotated by 90° to form the reverse-transmitted b4. The reflected waves b4 and a4 are delayed again by the polarization-coupled delay module to output a5 and b5. After being incident at the other end of the optical circulators 3A and 3B, a6 and b6 are generated respectively. The photodetectors 6A and 6B convert the reflected waves into two delayed microwave frequency discrimination signals, O1 and O2, to complete the modulation and delay control of optical radio.

[0071] Another aspect of this application discloses an optical modulation link control device, as shown in Figure 9. The device includes: a control module 11: two optical carrier signals are transmitted forward through corresponding optical circulators to a polarization coupling and delay module, which performs coupling and delay control on the two signals and outputs two modulated lights with orthogonal polarization planes; a reflection module 12: the two modulated lights are incident on a Faraday rotation reflection module, and after reflection, two reflected light signals are formed and transmitted in the opposite direction. The two reflected light signals are transmitted back to the polarization coupling and delay module for secondary delay and wavelength division control, and output two independent reflected light signals; and a photoelectric conversion module 13: the two independent reflected light signals are incident in the opposite direction through corresponding optical circulators to a photodetector, which performs photoelectric conversion and signal amplification on the two reflected light signals and outputs two delayed microwave frequency discrimination signals.

[0072] Since the principle by which this device solves the problem is similar to the methods described above, the implementation of this device can be found in the implementation of the methods, and will not be repeated here.

[0073] In another aspect, this application discloses an optical modulation link control system, including the optical modulation link control device as described above.

[0074] Since the principle by which this system solves the problem is similar to the methods and apparatus described above, the implementation of this system can be found in the implementation of the methods and apparatus, and will not be repeated here.

[0075] This application also provides a computer programmable logic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described method.

[0076] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0077] Those skilled in the art will understand that the embodiments of this application can provide methods, systems, or computer programs that produce the systems, apparatuses, modules, or units described in the above embodiments. Specifically, they can be implemented by computer chips or entities, or by products with certain functions. A typical implementation of a programmable logic device is a computer programmable logic device. Specifically, a computer programmable logic device can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation programmable logic device, email programmable logic device, game console, tablet computer, wearable programmable logic device, or any combination of these programmable logic devices.

[0078] In a typical example, a computer programmable logic device specifically includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the method executed by the client as described above, or the method executed by the server as described above.

[0079] Referring now to FIG10, a schematic diagram of the structure of a computer programmable logic device 600 suitable for implementing embodiments of the present application is shown.

[0080] As shown in Figure 10, the computer programmable logic device 600 includes a central processing unit (CPU) 601, which can perform various appropriate tasks and processes according to a program stored in read-only memory (ROM) 602 or a program loaded from storage section 608 into random access memory (RAM) 603. The RAM 603 also stores various programs and data required for the operation of the computer programmable logic device 600. The CPU 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0081] The following components are connected to I / O interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including a cathode ray tube (CRT), liquid crystal feedback (LCD), etc., and speakers, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card, modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to I / O interface 605 as needed. A removable medium 611, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 610 as needed so that computer programs read from it can be installed in storage section 608 as needed.

[0082] In particular, according to embodiments of this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program including program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 609, and / or installed from removable medium 611.

[0083] Computer-readable media include both permanent and non-permanent, removable and non-removable media that can store information by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage, programmable logic devices, or any other non-transferable media that can be used to store information accessible by a computer programmable logic device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0084] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0085] This application is described with reference to flowchart illustrations and / or block diagrams of methods, programmable logic devices (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing programmable logic device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing programmable logic device, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0086] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing programmable logic device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0087] These computer program instructions may also be loaded onto a computer or other programmable data processing programmable logic device to cause a series of operational steps to be performed on the computer or other programmable logic device to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable logic device, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0088] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or programmable logic device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or programmable logic device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or programmable logic device that includes said element.

[0089] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0090] This application can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This application can also be practiced in distributed computing environments where tasks are performed by remotely processed programmable logic devices connected via a communication network. In a distributed computing environment, program modules can reside in local and remote computer storage media, including storage for programmable logic devices.

[0091] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0092] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for controlling an optical modulation link, characterized in that, The method includes: two optical carrier signals are transmitted forward through corresponding optical circulators to a polarization coupling and delay module, where the two signals are coupled and delayed to output two modulated lights with orthogonal polarization planes; the two modulated lights are incident on a Faraday rotation reflection module, and after reflection, two reflected light signals are generated and transmitted in opposite directions; the two reflected light signals are transmitted back to the polarization coupling and delay module for secondary delay and wavelength division control to output two independent reflected light signals; the two independent reflected light signals are incident in opposite directions through corresponding optical circulators to a photodetector, where the photodetector performs photoelectric conversion and signal amplification on the two reflected light signals respectively, and outputs two delayed microwave frequency discrimination signals for optical radio phase noise measurement.

2. The optical modulation link control method according to claim 1, characterized in that, Before the two modulated optical carrier signals are transmitted forward through their respective optical circulators to the polarization coupling and delay module, the method further includes: the dual-wavelength light source outputs two optical signals, which are transmitted to two modulation modules with identical structures. The two modulation modules process the input optical signals and output two optical carrier signals with orthogonal polarization planes.

3. The optical modulation link control method according to claim 2, characterized in that, The two modulation modules process the input optical signal by: a polarization controller within the modulation module receiving the optical signal, adjusting the polarization state of the optical signal, and outputting a polarization-stable optical signal; the polarization-stable optical signal being transmitted to a reverse isolator within the modulation module, where the reverse isolator suppresses back-reflected light interference, and outputting an optical signal without back-reflection interference; and the optical signal without back-reflection interference being transmitted to a modulator within the modulation module, where the modulator performs microwave modulation on the optical signal and outputs an optical carrier signal.

4. The optical modulation link control method according to claim 1, characterized in that, The coupling and delay control of the two signals includes: the two optical carrier signals respectively enter the polarization optocoupler in the polarization coupling and delay module, and the two signals are coupled through the polarization optocoupler; the coupled signals are transmitted to the single-mode fiber delay array in the polarization coupling and delay module, and the single-mode fiber delay array performs a delay of a preset time to output two modulated lights with orthogonal polarization planes.

5. The optical modulation link control method according to claim 1, characterized in that, The two reflected light signals that are transmitted in opposite directions after reflection include: the two modulated lights are respectively incident on two Faraday rotator mirrors in the Faraday rotator reflection module; the Faraday rotator mirrors reflect the incident modulated light, and at the same time rotate the polarization plane of the reflected light by 90° through the built-in Faraday rotator; the polarization planes of the two reflected lights are controlled to remain orthogonal to each other, forming two reflected light signals that are transmitted in opposite directions.

6. The optical modulation link control method according to claim 4, characterized in that, The polarization coupling and delay module performs secondary delay and wavelength division control as follows: the two reflected light signals are transmitted back to the single-mode fiber delay array, and then subjected to secondary delay processing for a preset duration by the single-mode fiber delay array; the two signals after secondary delay are transmitted to the polarization optocoupler, and then subjected to wavelength division processing by the polarization optocoupler to output two independent reflected light signals.

7. The optical modulation link control method according to claim 1, characterized in that, The two independent reflected light signals are respectively incident on the photodetector in reverse through the corresponding optical circulators, including: the two independent reflected light signals are respectively incident on the reflected signal input terminal of the corresponding optical circulator; the optical circulator performs directional filtering on the reflected light signals, so that the reflected light signals are transmitted along a preset reverse transmission path, and are emitted from the detector output terminal of the optical circulator and incident on the corresponding photodetector.

8. The optical modulation link control method according to claim 1, characterized in that, The photodetector performs photoelectric conversion and signal amplification on the two reflected light signals respectively, including: the photoelectric conversion unit of the photodetector receives the reflected light signal and converts the light signal into an electrical signal; the electrical signal is transmitted to the amplification unit of the photodetector, and is linearly amplified by the amplification unit to output a delayed microwave frequency discrimination signal that meets the preset amplitude requirements.

9. An optical modulation link control device, characterized in that, The device includes: a control module: two optical carrier signals are transmitted forward through corresponding optical circulators to a polarization coupling and delay module, which performs coupling and delay control on the two signals and outputs two modulated lights with orthogonal polarization planes; a reflection module: the two modulated lights are incident on a Faraday rotation reflection module, and after reflection, they form two reflected light signals that are transmitted in opposite directions. The two reflected light signals are transmitted back to the polarization coupling and delay module for secondary delay and wavelength division control, and output two independent reflected light signals; and a photoelectric conversion module: the two independent reflected light signals are incident in opposite directions through corresponding optical circulators to a photodetector, which performs photoelectric conversion and signal amplification on the two reflected light signals, and outputs two delayed microwave frequency discrimination signals.

10. An optical modulation link control system, characterized in that, The system includes the optical modulation link control device as described in claim 9.

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