A high-performance microwave frequency synthesis and control method based on optical frequency comb

Abstract

The application discloses a high-performance microwave frequency synthesis and control method based on an optical frequency comb, relates to the technical field of frequency synthesis, and comprises the following steps: an optical frequency comb outputs an optical signal, the optical signal passes through a first synthesis path and a second synthesis path to generate signals, signals, signals, signals and signals, and according to engineering actual needs, the signals, the signals and the signals are sent into a multi-frequency signal selection detection and control unit to generate required multi-path high-performance microwave frequency signals,..., and, and the signals are output to a subsequent system for use; and a matched control method is provided; according to the application, for the application scene of satellite-borne high-performance microwave signal synthesis and precise measurement, multi-path high-performance microwave frequency signals can be generated, and the frequency range covers from a low frequency band to a millimeter wave frequency band.

Description

Technical Field

[0001] This invention relates to the field of frequency synthesis technology, and specifically to a high-performance microwave frequency synthesis and control method based on an optical frequency comb. Background Technology

[0002] The statements in this section are provided only as background information in connection with this disclosure and may not constitute prior art.

[0003] In recent years, femtosecond laser technology has gradually developed into an important means of high-precision and high-accuracy measurement because it can achieve measurement accuracy that traditional lasers cannot achieve. In particular, the emergence of femtosecond laser optical frequency combs has greatly promoted the new development of technologies in the fields of next-generation optical metrology, optical clocks, ultra-stable sources, and lidar.

[0004] An optical frequency comb is a broadband spectrum output by a mode-locked femtosecond laser, featuring equally spaced coherent spectral lines. These coherent lines exhibit a "comb-like" distribution and roll off with increasing frequency. Given that the high-frequency component signals corresponding to the coherent spectral lines in the broadband spectrum of an optical frequency comb experience a greater attenuation due to the corresponding comb power roll-off with increasing frequency, traditional photoelectric detection methods often cannot obtain high-performance microwave frequency signals, and the frequency band is relatively low, typically covering only the L-band.

[0005] In practical engineering applications, traditional microwave frequency synthesis methods are limited by the performance of reference clocks (crystal oscillators, resonators, chip clocks), high frequency multiples in microwave / millimeter-wave bands, and phase-locked loop technology. This is in stark contrast to the high-performance requirements of next-generation wireless communication systems for microwave frequency signals, which are mainly manifested in aspects such as wide bandwidth, low phase noise, low spurious emissions, high stability, and strong environmental adaptability.

[0006] Therefore, using optical frequency combs as an ultra-stable time and frequency reference source, utilizing and maintaining the time and frequency characteristics of this reference source, and exploring methods for generating high-frequency, wide-coverage microwave frequency signals with ultra-low phase noise and high stability will become a new demand for fields such as high-performance radar, satellite navigation, precision measurement, and high-precision time and frequency transmission. Summary of the Invention

[0007] The purpose of this invention is to provide a high-performance microwave frequency synthesis and control method based on optical frequency comb, which addresses the problems existing in the prior art. This method is designed for spaceborne high-performance microwave signal synthesis and precision measurement applications, and can generate multiple high-performance microwave frequency signals covering the frequency range from low frequency bands to millimeter wave bands, thus solving the aforementioned problems.

[0008] The technical solution of the present invention is as follows:

[0009] A high-performance microwave frequency synthesis method based on an optical frequency comb, comprising:

[0010] Step S1: Split the optical signal output from the optical frequency comb into two optical signals;

[0011] Step S2: One optical signal is combined through the first synthesis path to generate a high-performance, low-spurious low-frequency band f1 signal and a high-performance, low-spurious low-frequency band f2 signal with frequency division characteristics; the other optical signal is combined through the second synthesis path to generate a high-performance, low-spurious high-frequency band f3 signal and a high-performance, low-spurious high-frequency band f4 signal.

[0012] Step S3: Combine the f2 and f3 signals to form a signal f5 with a fractional multiple of the original repetition frequency. The f5 signal can maintain the original high performance and low spurious characteristics, while taking into account the wide coverage of both low and high frequency bands.

[0013] Step S4: Based on actual engineering needs, send signals f1, f4, and f5 to the multi-frequency signal selection detection and control unit to generate the required multi-channel high-performance microwave frequency signals f OUT_1 f OUT_2 ... and f OUT_N The output is then used by subsequent systems.

[0014] Further, step S1 includes:

[0015] The optical signal output from the optical frequency comb is split into two optical signals by optical splitter unit a.

[0016] Further, the first synthesis path includes:

[0017] Photoelectric conversion unit a, electrical branching unit a, filtering unit a, low-noise amplitude and phase control unit a, electrical frequency division unit, filtering unit b, low-noise amplitude and phase control unit b.

[0018] Furthermore, the second synthesis path includes:

[0019] Optical frequency doubling control unit, optical splitter unit b, photoelectric conversion unit b, filter unit c, low noise amplitude and phase control unit c, electrical conversion unit c, filter unit d, low noise amplitude and phase control unit d.

[0020] Further, step S2 includes:

[0021] One optical signal is converted into a low-frequency electrical signal by photoelectric conversion unit a, and then split into two by electrical splitting unit: one path passes through filter unit a and low-noise amplitude and phase control unit a to generate a high-performance, low-spurious low-frequency f1 signal; the other path passes through electrical frequency division unit, filter unit b and low-noise amplitude and phase control unit b to generate a high-performance, low-spurious low-frequency f2 signal with frequency division characteristics.

[0022] The two optical signals are converted into new optical frequency comb signals with frequency doubling characteristics by the optical frequency doubling control unit, and then split into two paths by the optical splitting unit b: one path is converted into a high-performance, low-spurious high-frequency band f3 signal by the photoelectric conversion unit b, the filtering unit c and the low-noise amplitude and phase control unit c; the other path is converted into a high-performance, low-spurious high-frequency band f4 signal by the photoelectric conversion unit c, the filtering unit d and the low-noise amplitude and phase control unit d.

[0023] Further, step S3 includes:

[0024] Considering that the obtained f3 and f4 signals are both integer multiples of the original input optical frequency comb repetition frequency, the f2 and f3 signals are sent into the microwave frequency synthesis unit to output a new f5 signal with a fractional multiple of the original repetition frequency.

[0025] A high-performance microwave frequency synthesis control method based on an optical frequency comb includes:

[0026] The multi-frequency signal selection detection and control unit collects the working status of key units and obtains the corresponding status parameters;

[0027] The multi-frequency signal selection detection and control unit then performs online monitoring and closed-loop control, sending control parameters to key units and circuits for adjustment to maintain the stability of the synthesized high-performance microwave frequency signal.

[0028] Furthermore, the key unit includes: an optical part and a microwave part;

[0029] The optical section includes: optical splitter unit a, photoelectric conversion unit a, optical frequency doubling control unit, and optical splitter unit b; the microwave section includes: low noise amplitude and phase control unit a, low noise amplitude and phase control unit b, low noise amplitude and phase control unit c, low noise amplitude and phase control unit d, and microwave frequency synthesis unit.

[0030] Furthermore, specifically including:

[0031] In open-loop operation, the multi-frequency signal selection detection and control unit will acquire the corresponding state parameters of the optical and microwave components, and extract the open-loop parameter value (P) from the state parameters. i1 T i1 ), where P i1 T represents the power value. i1 The value represents the temperature, where i is determined based on the actual number of channels, i = 1, 2, ..., N; thus, the open-loop parameter value and the expected ground value (P) are obtained. i0 T i0 The difference between them is ΔP i1 =P i1 -P i0 and ΔT i1=T i1 -T i0 The difference is used to determine the current operating status and the expected value. and The difference between them;

[0032] In closed-loop operation, the multi-frequency signal selection detection and control unit performs closed-loop control of the optical and microwave components based on preset system judgment conditions. These control parameters include attenuation, phase, or the operating voltage / current of the internally configured heater / TEC. After a period of operation, new open-loop parameter values ​​(P) are obtained. i2 T i2 ), compared with the expected ground value (P) i0 T i0 The new difference between them is ΔP. i2 and ΔT i2 The difference is used to determine the relationship between the closed-loop control state and the expected value. and The gap between them and the implementation of adjustment strategies.

[0033] Furthermore, the method of determining the closed-loop control state and the expected value through the difference... and The gaps and adjustment strategies include:

[0034] Scenario 1: When When the power parameter configuration meets expectations, it can be determined that the configuration is as expected; when In this case, it can be determined that the current temperature parameter configuration meets expectations; or both can be used for a combined judgment.

[0035] Scenario 2: When At that time, according to ΔP i2 -ΔP i1 and ΔT i2 -ΔT i1 The magnitude of the difference is compensated and adjusted in reverse by the control parameters, and the new difference ΔP is obtained by using the status parameters of the returned signal. iM and ΔT iM Where M is the number of iterations, when the judgment condition of Case 1 is met, the closed-loop system can be considered to be stable and in equilibrium;

[0036] Scenario 3: In practical engineering applications, if the joint judgment cannot simultaneously meet the convergence conditions, the initial target value and control coefficient of the expected value can be adjusted by manual individual command control based on the iterative process information and the trend of state parameter changes, so that the closed-loop system can quickly converge to stability, thereby obtaining a high-performance and stable microwave frequency signal that is independent of environmental changes within a certain range.

[0037] Compared with existing technologies, the advantages of this invention are as follows:

[0038] 1. A method for synthesizing microwave frequency signals by converting optical frequency comb signals into microwave frequency signals was designed. The high-performance microwave frequency signals synthesized by this method have characteristics such as wide coverage, low phase noise, low spurious emissions, and fractional frequency division, while maintaining the high time-frequency stability of the optical frequency comb reference source.

[0039] 2. By using online open-loop / closed-loop control methods, the key units and circuits in the optical and microwave parts of this system are monitored, regulated, and controlled online to obtain high-performance and stable microwave frequency signals that are independent of environmental changes within a certain range. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a high-performance microwave frequency synthesis principle based on an optical frequency comb;

[0041] Figure 2 This is a block diagram illustrating the principle of high-performance microwave frequency signal control. Detailed Implementation

[0042] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus 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 apparatus. 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 apparatus that includes said element.

[0043] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0044] Example 1

[0045] Please see Figure 1 A high-performance microwave frequency synthesis method based on an optical frequency comb specifically includes the following steps:

[0046] Step S1: Split the optical signal output from the optical frequency comb into two optical signals;

[0047] Step S2: One optical signal is combined through the first synthesis path to generate a high-performance, low-spurious low-frequency band f1 signal and a high-performance, low-spurious low-frequency band f2 signal with frequency division characteristics; the other optical signal is combined through the second synthesis path to generate a high-performance, low-spurious high-frequency band f3 signal and a high-performance, low-spurious high-frequency band f4 signal.

[0048] Step S3: Combine the f2 and f3 signals to form a signal f5 with a fractional multiple of the original repetition frequency. The f5 signal can maintain the original high performance and low spurious characteristics, while taking into account the wide coverage of both low and high frequency bands.

[0049] Step S4: Based on actual engineering needs, send signals f1, f4, and f5 to the multi-frequency signal selection detection and control unit to generate the required multi-channel high-performance microwave frequency signals f OUT_1 f OUT_2 ... and f OUT_N The output is then used by subsequent systems.

[0050] In this embodiment, specifically, step S1 includes:

[0051] The optical signal output from the optical frequency comb is split into two optical signals by optical splitter unit a.

[0052] In this embodiment, specifically, the first synthesis path includes:

[0053] Photoelectric conversion unit a, electrical branching unit a, filtering unit a, low-noise amplitude and phase control unit a, electrical frequency division unit, filtering unit b, low-noise amplitude and phase control unit b.

[0054] In this embodiment, specifically, the second synthesis path includes:

[0055] Optical frequency doubling control unit, optical splitter unit b, photoelectric conversion unit b, filter unit c, low noise amplitude and phase control unit c, electrical conversion unit c, filter unit d, low noise amplitude and phase control unit d.

[0056] In this embodiment, specifically, step S2 includes:

[0057] One optical signal is converted into a low-frequency electrical signal by photoelectric conversion unit a, and then split into two by electrical splitting unit: one path passes through filter unit a and low-noise amplitude and phase control unit a to generate a high-performance, low-spurious low-frequency f1 signal; the other path passes through electrical frequency division unit, filter unit b and low-noise amplitude and phase control unit b to generate a high-performance, low-spurious low-frequency f2 signal with frequency division characteristics.

[0058] The two optical signals are converted into new optical frequency comb signals with frequency doubling characteristics by the optical frequency doubling control unit, and then split into two paths by the optical splitting unit b: one path is converted into a high-performance, low-spurious high-frequency band f3 signal by the photoelectric conversion unit b, the filtering unit c and the low-noise amplitude and phase control unit c; the other path is converted into a high-performance, low-spurious high-frequency band f4 signal by the photoelectric conversion unit c, the filtering unit d and the low-noise amplitude and phase control unit d.

[0059] In this embodiment, specifically, step S3 includes:

[0060] Considering that the obtained f3 and f4 signals are both integer multiples of the original input optical frequency comb repetition frequency, the f2 and f3 signals are sent into the microwave frequency synthesis unit to output a new f5 signal with a fractional multiple of the original repetition frequency.

[0061] In response to drastic changes in the external environment of a spacecraft, characteristics such as deteriorated optical signal modulation and large fluctuations in microwave signal power and latency often occur. According to Figure 2 The block diagram shown illustrates a high-performance microwave frequency synthesis control method based on an optical frequency comb, comprising:

[0062] The multi-frequency signal selection detection and control unit collects the working status of key units and obtains the corresponding status parameters;

[0063] The multi-frequency signal selection detection and control unit then performs online monitoring and closed-loop control, sending control parameters to key units and circuits for adjustment to maintain the stability of the synthesized high-performance microwave frequency signal.

[0064] In this embodiment, specifically, the key unit includes: an optical part and a microwave part;

[0065] The optical section includes: optical splitter unit a, photoelectric conversion unit a, optical frequency doubling control unit, and optical splitter unit b; the microwave section includes: low noise amplitude and phase control unit a, low noise amplitude and phase control unit b, low noise amplitude and phase control unit c, low noise amplitude and phase control unit d, and microwave frequency synthesis unit.

[0066] In this embodiment, specifically, it includes:

[0067] In open-loop operation, the multi-frequency signal selection detection and control unit will acquire the corresponding state parameters of the optical and microwave components, and extract the open-loop parameter value (P) from the state parameters. i1 T i1 ), where P i1 T represents the power value. i1 The value represents the temperature, where i is determined based on the actual number of channels, i = 1, 2, ..., N; thus, the open-loop parameter value and the expected ground value (P) are obtained.i0 T i0 The difference between them is ΔP i1 =P i1 -P i0 and ΔT i1 =T i1 -T i0 The difference is used to determine the current operating status and the expected value. and The difference between them;

[0068] In closed-loop operation, the multi-frequency signal selection detection and control unit performs closed-loop control of the optical and microwave components based on preset system judgment conditions. These control parameters include attenuation, phase, or the operating voltage / current of the internally configured heater / TEC. After a period of operation, new open-loop parameter values ​​(P) are obtained. i2 T i2 ), compared with the expected ground value (P) i0 T i0 The new difference between them is ΔP. i2 and ΔT i2 The difference is used to determine the relationship between the closed-loop control state and the expected value. and The gap between them and the implementation of adjustment strategies.

[0069] In this embodiment, specifically, the step of determining the closed-loop control state and the expected value through the difference is... and The gaps and adjustment strategies include:

[0070] Scenario 1: When When the power parameter configuration meets expectations, it can be determined that the configuration is as expected; when In this case, it can be determined that the current temperature parameter configuration meets expectations; or both can be used for a combined judgment.

[0071] Scenario 2: When At that time, according to ΔP i2 -ΔP i1 and ΔT i2 -ΔT i1 The magnitude of the difference is compensated and adjusted in reverse by the control parameters, and the new difference ΔP is obtained by using the status parameters of the returned signal. iM and ΔT iM Where M is the number of iterations, when the judgment condition of Case 1 is met, the closed-loop system can be considered to be stable and in equilibrium;

[0072] Scenario 3: In practical engineering applications, if the joint judgment cannot simultaneously meet the convergence conditions, the initial target value and control coefficient of the expected value can be adjusted by manual individual command control based on the iterative process information and the trend of state parameter changes, so that the closed-loop system can quickly converge to stability, thereby obtaining a high-performance and stable microwave frequency signal that is independent of environmental changes within a certain range.

[0073] Example 2

[0074] Example 2: To verify the correctness, according to... Figure 1 and Figure 2 The design presents a prototype optical / microwave frequency signal synthesizer. This prototype can convert an input 200MHz 1550nm optical frequency comb signal into a multi-frequency microwave signal. The required output frequency value and the input optical frequency comb signal parameters (pulse repetition frequency f) are used to determine the optimal output frequency. rep The following microwave frequency signal is obtained by calculation (=200MHz), which supports online status monitoring and signal performance regulation, and maintains the stability of the time and frequency characteristics of the output signal.

[0075] f OUT_1 =f1=3×f rep =600MHz;

[0076] f OUT_2 =f2=4.5×f rep =900MHz;

[0077] f OUT_3 =f3=134×f rep =26800MHz;

[0078] f OUT_4 =f5=138.5×f rep =27700MHz;

[0079] f OUT_5 =f4=152×f rep =30400MHz.

[0080] The microwave frequency signal synthesized by this method has the characteristics of wide frequency coverage, low phase noise, low spurious emissions and stable time and frequency characteristics. It can provide the time and frequency reference source, local clock and local oscillator frequency signal required for applications such as space optical frequency comb, laser communication, high-precision time and frequency transmission and precision measurement.

[0081] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0082] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A high-performance microwave frequency synthesis method based on an optical frequency comb, characterized in that, include: Step S1: Split the optical signal output from the optical frequency comb into two optical signals; Step S2: One optical signal is used to generate a low-frequency band through the first synthesis path. Signals and low-frequency bands with frequency division characteristics The signal; another optical signal is generated in the high-frequency band via a second synthesis path. Signals and high-frequency bands Signal; Step S3: [The text appears to be incomplete and contains several grammatical errors. A more accurate translation would require the full Signals and Signal synthesis has a fractional multiple of the original repetition frequency. The signal, the The signal can maintain its original characteristics while taking into account a wide coverage range in both low and high frequency bands; Step S4: Based on the actual needs of the project, Signal, Signal, The signal is sent to the multi-frequency signal selection detection and control unit to generate the required multi-channel microwave frequency signals. , ,……and The output is then used by subsequent systems. Step S2 includes: One optical signal is converted into a low-frequency electrical signal by photoelectric conversion unit a, and then split into two by electrical splitting unit: one of them passes through filter unit a and low-noise amplitude and phase control unit a to generate a low-frequency signal. The signal; another path sequentially passes through the electrical frequency division unit, filter unit b, and low-noise amplitude and phase control unit b to generate a low-frequency band with frequency division characteristics. Signal; The two optical signals are converted into new optical frequency comb signals with frequency doubling characteristics by the optical frequency doubling control unit, and then split into two paths by the optical splitter unit b: one path is converted into a high-frequency band by the photoelectric conversion unit b, the filtering unit c, and the low-noise amplitude and phase control unit c. The signal is converted to a higher frequency band via photoelectric conversion unit c, filter unit d, and low-noise amplitude and phase control unit d. Signal.

2. The high-performance microwave frequency synthesis method based on optical frequency comb according to claim 1, characterized in that, Step S1 includes: The optical signal output from the optical frequency comb is split into two optical signals by optical splitter unit a.

3. The high-performance microwave frequency synthesis method based on an optical frequency comb according to claim 1, characterized in that, The first synthesis path includes: Photoelectric conversion unit a, electrical branching unit a, filtering unit a, low-noise amplitude and phase control unit a, electrical frequency division unit, filtering unit b, low-noise amplitude and phase control unit b.

4. The high-performance microwave frequency synthesis method based on an optical frequency comb according to claim 3, characterized in that, The second synthesis path includes: Optical frequency doubling control unit, optical splitter unit b, photoelectric conversion unit b, filter unit c, low noise amplitude and phase control unit c, electrical conversion unit c, filter unit d, low noise amplitude and phase control unit d.

5. The high-performance microwave frequency synthesis method based on an optical frequency comb according to claim 4, characterized in that, Step S3 includes: Consider the acquisition Signals and The signals are all integer multiples of the repetition frequency of the original input optical frequency comb. Signals and The signal is fed into the microwave frequency synthesis unit, which outputs a new frequency with a fractional multiple of the original repetition frequency. Signal.

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