An optical frequency and radio frequency synchronous transmission system

Abstract

An embodiment of the present application discloses an optical frequency and radio frequency synchronous transmission system. The synchronous transmission system includes: a first measurement module for generating and outputting a second signal and a third signal, wherein the generated second signal is fed back to a second optical fiber coupler; a fourth optical fiber coupler for outputting a part of the third signal and inputting another part to a sixth optical fiber coupler; a first interference module for generating a first compensation signal and outputting it to the first measurement module; a second measurement module for generating and outputting a fourth signal and a fifth signal, wherein the generated fourth signal is fed back to the second optical fiber coupler; a fifth optical fiber coupler for outputting a part of the fifth signal and inputting another part to the sixth optical fiber coupler; a second interference module for generating a second compensation signal and outputting it to the second measurement module. By adopting the methods of using the same clock and the same source and optical beat frequency detection, the present invention enables higher stability of the transmission of optical frequency and radio frequency in a free space link.

Description

Technical Field

[0001] This application relates to the field of optical time-frequency transfer technology. More specifically, this application relates to an optical frequency and radio frequency synchronous transfer system. Background Art

[0002] High-precision time and frequency transfer technology plays an important role in the fields of metrology science, national defense and military, positioning and navigation, deep space exploration, and space-earth / inter-satellite communication. At present, the relatively mature time-frequency transfer technologies mainly include wireless microwave transfer technology and fiber optic link time-frequency transfer technology. Among them, the wireless microwave transfer technology has the highest technology maturity and integration level and is the most widely used. However, its transfer accuracy can no longer meet the rapid development needs of quantum optical frequency standards. The fiber optic link time-frequency transfer technology has very high transfer accuracy and also has advantages such as high stability and low loss. However, in occasions where it is not convenient to lay optical fibers, such as in wide-area ranges and airborne dynamic targets, the fiber optic frequency transfer technology obviously cannot meet the requirements.

[0003] Free space laser time-frequency transfer technology has advantages such as strong directivity and high bandwidth, and can flexibly achieve high-precision time-frequency transfer in a variety of complex scenarios. Developing high-precision free space laser time-frequency transfer technology is an inevitable trend for realizing long-distance precise time-frequency comparison. Currently, the free space laser time-frequency transfer technology can only achieve the transfer of optical frequency signals or optical carrier radio frequency signals. However, in some application scenarios, the cross-frequency domain frequency signal transfer is very necessary. For example, optical frequency combs often require optical frequency signals as references for high-stability frequency locking. At the same time, most frequency signal generation and detection devices often require radio frequency signals as references to achieve frequency locking. Especially in emergency scenarios, quickly establishing high-stability optical frequency and radio frequency reference benchmarks for temporary nodes, and remotely injecting time-frequency signals with strong reliability and high stability are of great significance for forming a flexible space-time reference network. Summary of the Invention

[0004] The purpose of the present invention is to provide an optical frequency and radio frequency synchronous transfer system, which can make the stability of the optical frequency and radio frequency transfer in the free space link higher by adopting the methods of using the same clock and the same source and optical beat frequency detection.

[0005] In order to achieve at least one of the above purposes, this application adopts the following technical solutions:

[0006] This application provides an optical frequency and radio frequency synchronous transfer system. The synchronous transfer system includes: a laser, a first fiber optic coupler, a second fiber optic coupler, a fourth fiber optic coupler, a first measurement module, a first interference module; a third fiber optic coupler, a fifth fiber optic coupler, a second measurement module, a second interference module, a rubidium clock; a sixth fiber optic coupler, a first detector;

[0007] The laser is used to output a first signal to the first optical fiber coupler, which divides the first signal into two paths, one path is output to the second optical fiber coupler, and the other path is output to the third optical fiber coupler;

[0008] The rubidium clock is used to output a seventh signal to the first interference module and the second interference module;

[0009] The first measurement module is used to generate and output a second signal and a third signal according to the first signal output by the second optical fiber coupler and the first compensation signal output by the first interference module, wherein the generated second signal is fed back to the second optical fiber coupler;

[0010] The fourth optical fiber coupler is used to couple the third signal output by the first measurement module, and output a part of the third signal, and input the other part to the sixth optical fiber coupler;

[0011] The first interference module is used to generate a first compensation signal according to the first signal, the second signal and the seventh signal output by the second optical fiber coupler, and output it to the first measurement module;

[0012] The second measurement module is used to generate and output a fourth signal and a fifth signal according to the first signal output by the third optical fiber coupler and the second compensation signal output by the second interference module, wherein the generated fourth signal is fed back to the second optical fiber coupler;

[0013] The fifth optical fiber coupler is used to couple the fifth signal output by the second measurement module, and output a part of the fifth signal, and input the other part to the sixth optical fiber coupler;

[0014] The second interference module is used to generate a second compensation signal according to the first signal, the fourth signal and the seventh signal output by the third optical fiber coupler, and output it to the second measurement module;

[0015] The first detector is used to output a sixth signal according to the third signal and the fifth signal output by the sixth optical fiber coupler.

[0016] Optionally, the first measurement module includes:

[0017] A first acousto-optic modulator, a first Faraday rotator, a first optical terminal, a first semi-transparent and semi-reflective mirror, a first free space link;

[0018] The first acousto-optic modulator can generate a first intermediate signal according to the first signal and the first compensation signal;

[0019] The first Faraday rotator can generate a second intermediate signal according to the first intermediate signal;

[0020] The first optical terminal can output the second intermediate signal to the first semi-transparent and semi-reflective mirror;

[0021] There is a first free - space link for the passage of the second intermediate signal between the first optical terminal and the first half - transparent and half - reflecting mirror;

[0022] After the second intermediate signal passes through the first free - space link, a third signal is generated. Part of the third signal is input to the first optical terminal after being reflected by the first half - transparent and half - reflecting mirror, and then passes through the first optical terminal, the first Faraday rotator, and the first acousto - optic modulator in sequence to generate a second signal. Part of the third signal is output to the fourth fiber optic coupler, and the fourth fiber optic coupler outputs a part of the third signal and inputs the other part to the first detector.

[0023] Optionally, the second measurement module includes:

[0024] A second acousto - optic modulator, a second Faraday rotator, a second optical terminal, a second half - transparent and half - reflecting mirror, and a second free - space link;

[0025] The second acousto - optic modulator can generate a third intermediate signal according to the first signal and the second compensation signal;

[0026] The second Faraday rotator can generate a fourth intermediate signal according to the third intermediate signal;

[0027] The second optical terminal can output the fourth intermediate signal to the second half - transparent and half - reflecting mirror;

[0028] There is a second free - space link for the passage of the fourth intermediate signal between the second optical terminal and the second half - transparent and half - reflecting mirror;

[0029] After the fourth intermediate signal passes through the second free - space link, a fifth signal is generated. Part of the fifth signal is input to the second optical terminal after being reflected by the second half - transparent and half - reflecting mirror, and then passes through the second optical terminal, the second Faraday rotator, and the second acousto - optic modulator in sequence to generate a fourth signal. Part of the fifth signal is output to the fifth fiber optic coupler, and the fifth fiber optic coupler outputs a part of the fifth signal and inputs the other part to the first detector.

[0030] Optionally, the first interference module includes:

[0031] A second detector, a first mixer, a first PI controller, a first signal generator, and a first amplifier;

[0032] The second detector is used to generate a first beat signal according to the first signal and the second signal output by the second fiber optic coupler;

[0033] The first mixer generates a first mixed signal according to the first beat signal output by the second detector;

[0034] The first PI controller generates a first loop compensation signal according to the first mixing signal output by the first mixer;

[0035] The first signal generator generates a first homologous signal and a first compensation signal according to the first loop compensation signal output by the first PI controller and the seventh signal output by the rubidium clock, and outputs the first homologous signal to the first mixer;

[0036] The first amplifier amplifies the first compensation signal output by the first signal generator and then outputs the first compensation signal to the first acousto-optic modulator.

[0037] Optionally, the synchronous transfer system further includes a first reference arm, and the first reference arm includes a first Faraday mirror for reflecting the first signal so that the first signal is output to the first interference module through the second fiber optic coupler.

[0038] Optionally, the second interference module includes:

[0039] A third detector, a second mixer, a second PI controller, a second signal generator, a second amplifier;

[0040] The third detector is used to generate a second beat frequency signal according to the first signal and the fourth signal output by the third fiber optic coupler;

[0041] The second mixer generates a second mixing signal according to the second beat frequency signal output by the third detector;

[0042] The second PI controller generates a second loop compensation signal according to the second mixing signal output by the second mixer;

[0043] The second signal generator is used to generate a second homologous signal and a second compensation signal according to the second loop compensation signal output by the second PI controller and the seventh signal output by the rubidium clock, and output the second homologous signal to the second mixer;

[0044] The second amplifier amplifies the second compensation signal output by the second signal generator and then outputs the second compensation signal to the second acousto-optic modulator.

[0045] Optionally, the synchronous transfer system further includes a second reference arm, and the second reference arm includes a second Faraday mirror for reflecting the first signal so that the first signal is output to the second interference module through the fourth fiber optic coupler.

[0046] Optionally, the first homologous signal and the second homologous signal are RF signals with different frequencies. The beneficial effects of this application are as follows:

[0047] Compared with the prior art, the present invention realizes dual-channel optical frequency transfer by suppressing link phase noise. On this basis, by performing optical heterodyne interference detection on the two optical frequency signals, the synchronous transfer of the optical frequency and the radio frequency is realized, and the transfer stability is improved.

[0048] This system uses a rubidium clock to emit a seventh signal to form a first homologous signal and a second homologous signal with the same source but different frequencies, and then forms a first compensation signal and a second compensation signal with the same source. Moreover, a ultra-stable laser is used to emit a first signal, realizing the same optical frequency reference source and radio frequency reference source. On the premise of dynamically compensating the link phase noise and ensuring the stable transfer of the optical frequency signal, beat frequency detection is performed on the two optical frequency signals, thereby eliminating the link common-mode noise and further improving the transfer stability of the radio frequency signal in the free space link. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention will be further described in detail below with reference to the drawings.

[0050] Figure 1 The system block diagram showing an embodiment of the present application is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is obvious that these embodiments can also be implemented without these specific details.

[0052] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. Unless otherwise clearly specified and defined, the terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0053] It should also be noted that in the description of the present application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0054] To solve the problems existing in the prior art, an embodiment of the present application provides an optical frequency and radio frequency synchronous transmission system, which can achieve high-precision and stable transmission of optical frequency signals, such as Figure 1 As shown, the synchronous transmission system includes: an ultra-stable laser, a first optical fiber coupler, a second optical fiber coupler, a fourth optical fiber coupler, a first measurement module, a first interference module; a third optical fiber coupler, a fifth optical fiber coupler, a second measurement module, a second interference module, a rubidium clock; a sixth optical fiber coupler, a first detector; specifically, the first optical fiber coupler is a 1×2 optical fiber coupler, the second optical fiber coupler and the third optical fiber coupler are respectively 2×2 optical fiber couplers, the fourth optical fiber coupler and the fifth optical fiber coupler are respectively 1×2 optical fiber couplers, and the sixth optical fiber coupler is a 2×1 optical fiber coupler.

[0055] As Figure 1 shown, the output end of the ultra-stable laser is connected to the input end of the first optical fiber coupler, and the output end of the first optical fiber coupler is connected to one input end of the second optical fiber coupler and the third optical fiber coupler.

[0056] One output end of the second optical fiber coupler is connected to the input end of the first measurement module, and the other output end is connected to the input end of the first interference module. The other input end of the second optical fiber coupler is connected with a first reference arm. The output end of the first measurement module is connected to the input end of the fourth optical fiber coupler, and the output end of the fourth optical fiber coupler is connected to one input end of the sixth optical fiber coupler;

[0057] One output end of the third optical fiber coupler is connected to the input end of the second measurement module, and the other output end is connected to the input end of the second interference module. The other input end of the third optical fiber coupler is connected with a first reference arm. The output end of the second measurement module is connected to the input end of the fifth optical fiber coupler, and the output end of the fifth optical fiber coupler is connected to the other input end of the sixth optical fiber coupler. The output end of the sixth optical fiber coupler is connected to the input end of the first detector, and the output end of the first detector is connected to the outside.

[0058] The ultra-stable laser is used to output the first signal νt to the first fiber optic coupler, and the first fiber optic coupler transmits the first signal νt to two optical frequency links, one output to the second fiber optic coupler and the other output to the third fiber optic coupler; the first signal νt is an optical frequency signal. Assuming the frequency of the optical frequency signal is ν, then νt represents its phase magnitude. The second fiber optic coupler outputs a part of the first signal νt to the first measurement module, and the other part passes through the first reference arm. The first reference arm includes a first Faraday mirror. The first signal νt is reflected by the first Faraday mirror, and after the polarization state rotates 90°, it is output to the first interference module.

[0059] The third fiber optic coupler outputs a part of the first signal νt to the second measurement module, and the other part passes through the second reference arm. The second reference arm includes a second Faraday mirror. The first signal νt is reflected by the second Faraday mirror, and after the polarization state rotates 90°, it enters the second interference module. Both optical frequency links adopt the Michelson interferometer principle to obtain the beat signal with link noise through optical heterodyne interference.

[0060] Specifically, the rubidium clock in this synchronous transmission system is used to output the seventh signal f ref t to the first interference module to generate the first homologous signal 2f AOM1 t and to the second interference module to generate the second homologous signal 2f AOM2 t. The first homologous signal 2f AOM1 t and the second homologous signal 2f AOM2 t are radio frequency signals with the same origin but different frequencies.

[0061] The first measurement module is used to generate and output the second signal and the third signal according to the first signal νt output by the second fiber optic coupler and the first compensation signal output by the first interference module. Among them, the generated second signal is fed back to the second fiber optic coupler; as Figure 1 shown, the first measurement module includes: a first acousto-optic modulator, a first Faraday rotator, a first optical terminal, a first semi-transparent and semi-reflective mirror, and a first free space link; specifically, the input end of the first acousto-optic modulator is the input end of the first measurement module. The input end of the first acousto-optic modulator is connected to an output end of the second fiber optic coupler. The output end of the first acousto-optic modulator is connected to the input end of the first Faraday rotator. The output end of the first Faraday rotator is connected to the input end of the first optical terminal. The output end of the first optical terminal is connected to the input end of the first free space link. The output end of the first free space link is connected to the input end of the first semi-transparent and semi-reflective mirror. The output end of the first semi-transparent and semi-reflective mirror is the output end of the first measurement module. The output end of the first semi-transparent and semi-reflective mirror is connected to the input end of the fourth fiber optic coupler.

[0062] The first acousto-optic modulator can generate a first intermediate signal according to the first signal νt and the first compensation signal Generate a first intermediate signal

[0063] The first Faraday rotator can generate a second intermediate signal according to the first intermediate signal, and the second intermediate signal is the inverted signal of the first intermediate signal;

[0064] The first optical terminal can output the second intermediate signal to the first semi-transmissive and semi-reflective mirror;

[0065] There is a first free space link for the second intermediate signal to pass through between the first optical terminal and the first semi-transmissive and semi-reflective mirror;

[0066] After passing through the first free space link, the second intermediate signal generates a third signal The third signal Part of the third signal is input to the first optical terminal after being reflected by the first semi-transmissive and semi-reflective mirror, and passes through the first optical terminal, the first Faraday rotator, and the first acousto-optic modulator in sequence to generate a second signal Part of the third signal Output to the fourth fiber optic coupler, and the fourth fiber optic coupler outputs a part of the third signal Output, and the other part is input to the first detector.

[0067] Specifically, assume that the operating frequency of the first acousto-optic modulator is f AOM1 , and at the same time, since the first acousto-optic modulator carries a compensation phase Then, after the first acousto-optic modulation, a first intermediate signal is generated After passing through the first Faraday rotator and the first optical terminal, the first intermediate signal enters the first free space link for propagation. Assume that the one-way transmission delay of the link is t1, then the third signal generated after passing through the first free space link can be expressed as Among them, the link noise Δt1 is the delay deviation caused by the phase noise introduced by the free space link.

[0068] The third signal Part of it passes through the first semi-transmissive and semi-reflective mirror and enters the 1×2 fiber optic coupler, and the other part is reflected and returns to the first optical terminal. Since the phase noise introduced during the round trip of the third signal is the same, the optical frequency signal after return can be expressed as After passing through the first acousto-optic modulator again, a second signal is generated

[0069] After that, the second signal The first interference module is used to generate a first signal νt and a second signal νt according to the output of the second optical fiber coupler. and the seventh signal f ref tGenerate the first compensation signal And output to the first measurement module, such as Figure 1 As shown, the first interference module includes: a second detector, a first mixer, a first PI controller, a first signal generator, and a first amplifier; specifically, the input end of the second detector is the input end of the first interference module, the input end of the second detector is connected to the output end of the second fiber coupler, the output end of the second detector is connected to the input end of the first mixer, the output end of the first mixer is connected to the input end of the first PI controller, the output end of the first PI controller and the output end of the rubidium clock are respectively connected to the input end of the first signal generator, the output end of the first signal generator is respectively connected to the input ends of the first amplifier and the first mixer, and the output end of the first amplifier is connected to the input end of the first acousto-optic modulator.

[0070] The second detector is used for detecting the first signal νt and the second signal νt output by the second optical fiber coupler. Generate the first beat signal Among them, -2νt1-2f AOM1 t1 is a constant term that does not change with time and can be ignored;

[0071] The first mixer generates a first beat frequency signal according to the first beat frequency signal output by the second detector. Generate the first mixing signal

[0072] The first PI controller outputs a first mixing signal according to the first mixer. Perform loop compensation to generate a first loop compensation signal

[0073] The first signal generator generates a first loop compensation signal according to the first PI controller output The seventh signal f output by the rubidium clock ref t, generating the first homologous signal 2f AOM1 t and the first compensation signal Then the link noise compensation is realized and the first homologous signal 2f AOM1 t is output to the first mixer;

[0074] The first amplifier converts the first compensation signal output by the first signal generator into After amplification, the first compensation signal is output to the first AOM.

[0075] The fourth optical fiber coupler is used to couple the third signal output by the first measurement module. and output a part of the third signal and input the other part to the sixth optical fiber coupler;

[0076] Similarly, the other link actively compensates for the link noise in the same way. The difference is that this link uses f AOM2 radio frequency signals with the same source but different frequencies for compensation. The link noise can be expressed as Since the two links are relatively close, it can be considered that the time delays and the changes in time delays of the two paths are approximately equal, that is, t1≈t2, Δt1≈Δt2.

[0077] Specifically, the second measurement module is used to generate and output a fourth signal and a fifth signal based on the first signal νt output by the third optical fiber coupler and the second compensation signal output by the second interference module. Among them, the generated fourth signal is fed back to the second optical fiber coupler; the second measurement module includes: a second acousto-optic modulator, a second Faraday rotator, a second optical terminal, a second half-transmissive and half-reflective mirror, a second free space link; specifically, the input end of the second acousto-optic modulator is the input end of the second measurement module. The input end of the second acousto-optic modulator is connected to an output end of the third optical fiber coupler. The output end of the second acousto-optic modulator is connected to the input end of the second Faraday rotator. The output end of the second Faraday rotator is connected to the input end of the second optical terminal. The output end of the second optical terminal is connected to the input end of the second free space link. The output end of the second free space link is connected to the input end of the second half-transmissive and half-reflective mirror. The output end of the second half-transmissive and half-reflective mirror is the output end of the second measurement module. The output end of the second half-transmissive and half-reflective mirror is connected to the input end of the fifth optical fiber coupler.

[0078] The second acousto-optic modulator can generate a third intermediate signal according to the first signal νt and the second compensation signal.

[0079] The second Faraday rotator can generate a fourth intermediate signal according to the third intermediate signal, and the fourth intermediate signal is the inverted signal of the third intermediate signal;

[0080] The second optical terminal can output the fourth intermediate signal to the second half-transmissive and half-reflective mirror;

[0081] A second free space link for the fourth intermediate signal to pass through is included between the second optical terminal and the second half-transmissive and half-reflective mirror;

[0082] The fifth signal is generated after the fourth intermediate signal passes through the second free space link. The fifth signal The part of the input that is reflected by the second semi-transmissive and semi-reflective mirror is input to the second optical terminal, and after passing through the second optical terminal, the second Faraday rotator, and the second acousto-optic modulator in sequence, a fourth signal is generated. Part of the fifth signal is output to the fifth fiber optic coupler, and the fifth fiber optic coupler outputs a part of the fifth signal and inputs the other part to the first detector.

[0083] The fifth fiber optic coupler is used to couple the fifth signal output by the second measurement module and output the fifth signal with a part output and the other part input to the sixth fiber optic coupler;

[0084] The second interference module is used to generate a second compensation signal according to the first signal νt and the fourth signal output by the third fiber optic coupler and the seventh signal f ref t and output it to the second measurement module; the second interference module includes: a third detector, a second mixer, a second PI controller, a second signal generator, and a second amplifier; specifically, the input end of the third detector is the input end of the second interference module, the input end of the third detector is connected to the output end of the third fiber optic coupler, the output end of the third detector is connected to the input end of the second mixer, the output end of the second mixer is connected to the input end of the second PI controller, the output end of the second PI controller and the output end of the rubidium clock are respectively connected to the input end of the second signal generator, the output end of the second signal generator is respectively connected to the input ends of the second amplifier and the second mixer, and the output end of the second amplifier is connected to the input end of the second acousto-optic modulator.

[0085] The third detector is used to generate a second beat frequency signal according to the first signal νt and the fourth signal output by the third fiber optic coupler

[0086] The second mixer generates a second mixing signal according to the second beat frequency signal output by the third detector

[0087] The second PI controller generates a second loop compensation signal according to the second mixing signal output by the second mixer

[0088] The second signal generator is used to generate, according to the second loop compensation signal output by the second PI controller in combination with the seventh signal f output by the rubidium clock ref ​​​At time t, generate a second homologous signal 2f AOM2 At time t and the second compensation signal And output the second homologous signal 2f AOM2 At time t to the second mixer;

[0089] The second amplifier amplifies the second compensation signal output by the second signal generator And then outputs the second compensation signal To the second acousto-optic modulator.

[0090] The first detector is used to output a sixth signal with high stability according to the third signal And the fifth signal output by the sixth optical fiber coupler Further, the sixth signal is a radio frequency signal. After both optical frequency signals reach the far end, a part of the optical frequency signal is separated by the fourth optical fiber coupler and the fifth optical fiber coupler respectively and used as the optical frequency reference signal at the far end. Since the compensation phase Is conjugate opposite to the link noise Therefore, the optical frequency signal is stably transmitted. At the same time, the two optical frequency signals are subjected to beat frequency detection to obtain the sixth signal Among them, v(t2 - t1) is a constant term that can be ignored, And And And Cancel each other out respectively. In addition, since the present invention uses a homologous rubidium clock as the radio frequency reference signal, the modulation frequencies f AOM1 And f AOM2 Have a relatively high frequency stability between them. Therefore, the link noise And Are almost equal and can be regarded as common mode noise. Even if the link noise is not completely compensated and eliminated, it can be eliminated by beat frequency detection at the far end. Therefore, after beat frequency detection, a radio frequency signal with high stability can be obtained at the far end Wherein Is the phase constant.

[0091] It should be noted that: the partial transmission of the above signals is all the splitting of the signal intensity, so as to divide one signal into several signals.

[0092] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. An optical frequency and radio frequency synchronous transmission system, characterized in that The synchronous transmission system includes: a laser, a first optical fiber coupler, a second optical fiber coupler, a fourth optical fiber coupler, a first measurement module, a first interference module; a third optical fiber coupler, a fifth optical fiber coupler, a second measurement module, a second interference module, a rubidium clock; a sixth optical fiber coupler, a first detector; The laser is used to output a first signal to the first optical fiber coupler. The first optical fiber coupler divides the first signal into two paths, one path is output to the second optical fiber coupler, and the other path is output to the third optical fiber coupler; The rubidium clock is used to output a seventh signal to the first interference module and the second interference module; The first measurement module is used to generate and output a second signal and a third signal according to the first signal output by the second optical fiber coupler and the first compensation signal output by the first interference module. Among them, the generated second signal is fed back to the second optical fiber coupler; The fourth optical fiber coupler is used to couple the third signal output by the first measurement module and output a part of the third signal, and input the other part to the sixth optical fiber coupler; The first interference module is used to generate a first compensation signal according to the first signal, the second signal and the seventh signal output by the second optical fiber coupler, and output it to the first measurement module; The second measurement module is used to generate and output a fourth signal and a fifth signal according to the first signal output by the third optical fiber coupler and the second compensation signal output by the second interference module. Among them, the generated fourth signal is fed back to the second optical fiber coupler; The fifth optical fiber coupler is used to couple the fifth signal output by the second measurement module and output a part of the fifth signal, and input the other part to the sixth optical fiber coupler; The second interference module is used to generate a second compensation signal according to the first signal, the fourth signal and the seventh signal output by the third optical fiber coupler, and output it to the second measurement module; The first detector is used to output a sixth signal according to the third signal and the fifth signal output by the sixth optical fiber coupler.

2. The optical frequency and radio frequency synchronous transmission system according to claim 1, wherein: The first measurement module includes: a first acousto-optic modulator, a first Faraday rotator, a first optical terminal, a first semi-transparent and semi-reflective mirror, a first free space link; The first acousto-optic modulator generates a first intermediate signal according to the first signal and the first compensation signal; The first Faraday rotator generates a second intermediate signal according to the first intermediate signal; The first optical terminal outputs the second intermediate signal to the first semi-transparent and semi-reflective mirror; A first free space link for the second intermediate signal to pass through is included between the first optical terminal and the first semi-transparent and semi-reflective mirror; The second intermediate signal generates a third signal after passing through the first free space link. Part of the third signal is input to the first optical terminal after being reflected by the first semi-transparent and semi-reflective mirror, and then passes through the first optical terminal, the first Faraday rotator, and the first acousto-optic modulator in sequence to generate a second signal. Part of the third signal is output to the fourth optical fiber coupler, and the fourth optical fiber coupler outputs a part of the third signal and inputs the other part to the first detector.

3. The optical frequency and radio frequency synchronous transmission system according to claim 2, wherein: The second measurement module includes: a second acousto-optic modulator, a second Faraday rotator, a second optical terminal, a second semi-transparent and semi-reflective mirror, a second free space link; The second acousto-optic modulator generates a third intermediate signal according to the first signal and the second compensation signal; The second Faraday rotator generates a fourth intermediate signal according to the third intermediate signal; The second optical terminal outputs the fourth intermediate signal to the second half-transmissive and half-reflective mirror; A second free space link for the passage of the fourth intermediate signal is included between the second optical terminal and the second half-transmissive and half-reflective mirror; After passing through the second free space link, the fourth intermediate signal generates a fifth signal. A part of the fifth signal is input to the second optical terminal after being reflected by the second half-transmissive and half-reflective mirror, and successively passes through the second optical terminal, the second Faraday rotator, and the second acousto-optic modulator to generate a fourth signal. A part of the fifth signal is output to the fifth optical fiber coupler, and the fifth optical fiber coupler outputs a part of the fifth signal and inputs the other part to the first detector.

4. The optical frequency and radio frequency synchronous transmission system according to claim 3, wherein: The first interference module includes: A second detector, a first mixer, a first PI controller, a first signal generator, and a first amplifier; The second detector is used to generate a first beat frequency signal according to the first signal and the second signal output by the second optical fiber coupler; The first mixer generates a first mixed frequency signal according to the first beat frequency signal output by the second detector; The first PI controller generates a first loop compensation signal according to the first mixed frequency signal output by the first mixer; The first signal generator generates a first homologous signal and a first compensation signal according to the first loop compensation signal output by the first PI controller and the seventh signal output by the rubidium clock, and outputs the first homologous signal to the first mixer; The first amplifier amplifies the first compensation signal output by the first signal generator and outputs the first compensation signal to the first acousto-optic modulator.

5. The optical frequency and radio frequency synchronous transmission system according to claim 1, wherein: The synchronous transmission system further includes a first reference arm, and the first reference arm includes a first Faraday mirror for reflecting the first signal so that the first signal is output to the first interference module through the second optical fiber coupler.

6. The optical frequency and radio frequency synchronous transmission system according to claim 4, wherein: The second interference module includes: A third detector, a second mixer, a second PI controller, a second signal generator, and a second amplifier; The third detector is used to generate a second beat frequency signal according to the first signal and the fourth signal output by the third optical fiber coupler; The second mixer generates a second mixed frequency signal according to the second beat frequency signal output by the third detector; The second PI controller generates a second loop compensation signal according to the second mixed frequency signal output by the second mixer; The second signal generator is used to generate a second homologous signal and a second compensation signal according to the second loop compensation signal output by the second PI controller and the seventh signal output by the rubidium clock, and outputs the second homologous signal to the second mixer; The second amplifier amplifies the second compensation signal output by the second signal generator and outputs the second compensation signal to the second acousto-optic modulator.

7. The optical frequency and radio frequency synchronous transmission system according to claim 1, wherein: The synchronous transmission system further includes a second reference arm, and the second reference arm includes a second Faraday mirror for reflecting the first signal so that the first signal is output to the second interference module through the fourth optical fiber coupler.

8. The optical frequency and radio frequency synchronous transmission system according to claim 6, characterized in that: The first homologous signal and the second homologous signal are radio frequency signals of different frequencies.

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