A laser phase estimation method and device assisted by a single optical frequency comb

Abstract

The present invention discloses a laser phase estimation method and device assisted by a single optical frequency comb. The method comprises: obtaining a detection optical signal and a reference optical signal; measuring the spatial distance of a link to be measured using the detection optical signal to obtain a detection echo optical signal; performing double-sideband intensity modulation on the reference optical signal and the detection echo optical signal using a single-frequency microwave signal; performing beat frequency processing on the modulated reference optical signal and the modulated detection echo optical signal respectively to obtain a reference photocurrent signal and a detection echo photocurrent signal; performing analog-to-digital conversion on the reference photocurrent signal and the detection echo photocurrent signal; calculating the frequency components of the reference optical signal and the detection echo optical signal obtained by the beat frequency; deambiguating the phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal to obtain the precise spatial distance of the link to be measured. The present invention significantly improves the ranging speed while ensuring the ranging range and accuracy.

Description

Technical Field

[0001] The present invention relates to a method for optical frequency comb ranging, and in particular to a laser phase estimation ranging method and device assisted by a single optical frequency comb. Background Art

[0002] Laser ranging is a non-contact measurement technology characterized by excellent monochromaticity, strong directionality, and high ranging accuracy. It is widely used in defense, construction, aerospace, and engineering surveying. Among commonly used ranging methods, the pulse method calculates target distance by directly measuring the time difference between the transmitted and received pulses. This method is fast and has a range of up to kilometers, but its ranging accuracy is limited by the pulse width, reaching only millimeters. Frequency-sweep interferometry uses a continuous linear sweep of the laser to obtain time delay information at the interference frequency to calculate target distance. However, limitations in laser frequency tuning speed and subsequent algorithm processing result in slower measurement speeds. The phase method indirectly calculates target distance based on the phase difference between the modulated light wave and the measured distance. Its ranging accuracy relies on high-frequency signals, requiring high-performance detectors and high-speed ADCs. This results in high processor computation and hardware costs. Furthermore, because the phase obtained by the phase detector suffers from 2π ambiguity, the phase-pushing method is often used to address this issue. This requires modulating a series of microwave signals for phase unwrapping, limiting measurement speed. Optical frequency combs, with their ultra-high frequency stability, excellent coherence, and wide spectral range, have become a new measurement method, offering new insights and approaches to traditional absolute distance measurement techniques. For example, conventional dual-comb ranging methods require locking the repetition rate and absolute frequency of two frequency combs, making the system more complex and expensive.

[0003] In summary, existing optical ranging systems have the following problems: the pulse method cannot achieve high-precision optical delay measurement; many current high-precision and large-range ranging methods have high performance requirements for devices such as ADCs and slow ranging speeds; traditional dual-optical frequency comb ranging systems are complex and costly. Summary of the Invention

[0004] The present invention aims to solve any problem existing in the prior art and provide a laser phase estimation method and device assisted by a single optical frequency comb, thereby achieving high-precision and rapid ranging using a single optical frequency comb. The specific technical solution is as follows:

[0005] In a first aspect, the present invention provides a laser phase estimation method assisted by a single optical frequency comb, comprising:

[0006] Acquire a detection optical signal and a reference optical signal corresponding to the detection optical signal, wherein both the detection optical signal and the reference optical signal are optical frequency comb signals;

[0007] Using the detection optical signal to measure the spatial distance of the link to be measured, to obtain a detection echo optical signal;

[0008] Performing double-sideband intensity modulation on the reference optical signal and the detection echo optical signal using a single-frequency microwave signal;

[0009] performing beat frequency processing on the modulated reference optical signal and the modulated detection echo optical signal respectively to obtain a reference photocurrent signal and a detection echo photocurrent signal;

[0010] Performing analog-to-digital conversion on the reference photocurrent signal and the detection echo photocurrent signal;

[0011] respectively calculating in a digital domain the frequency components of the modulated reference optical signal and the detection echo optical signal obtained by beating the frequency components;

[0012] The phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal is defuzzified by using a time-combination method to obtain the precise spatial distance of the link to be measured.

[0013] Furthermore, acquiring the detection optical signal and a reference optical signal corresponding to the detection optical signal includes:

[0014] Performing gating processing on the repetition-locked optical frequency comb signal;

[0015] The gated optical frequency comb signal is divided into the reference optical signal and the detection optical signal.

[0016] Furthermore, performing double-sideband intensity modulation on the reference optical signal and the detection echo optical signal by using a single-frequency microwave signal includes:

[0017] The reference optical signal and the detection echo optical signal are subjected to double-sideband intensity modulation using a high-frequency microwave signal greater than 40 GHz.

[0018] Furthermore, the step of respectively calculating in the digital domain the frequency components of the modulated reference optical signal and the detection echo optical signal obtained by beating the frequency components includes:

[0019] In the digital domain, a first frequency component obtained by the beat frequency between the comb teeth at which the spacing between the reference optical signal after modulation and the reference optical signal before modulation is the smallest and a second frequency component obtained by the beat frequency with the second smallest comb tooth spacing are determined, as well as a first frequency component obtained by the beat frequency between the comb teeth at which the spacing between the detection echo optical signal after modulation and the detection echo optical signal before modulation is the smallest and a second frequency component obtained by the beat frequency with the second smallest comb tooth spacing are determined.

[0020] Furthermore, the method of using a time-combined method to deambiguate the phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal to obtain the spatial distance of the link to be measured includes:

[0021] Calculating the integer ambiguity corresponding to the phase difference between the reference photocurrent signal and the corresponding frequency component of the detection echo photocurrent signal using a time-combined method;

[0022] Calculating the precise time delay introduced by the spatial link to be measured using the integer ambiguity;

[0023] The spatial distance of the link to be measured is calculated according to the precise time delay.

[0024] Furthermore, the calculating of the integer ambiguity corresponding to the phase difference between the reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal by using the time-combined method includes:

[0025] Extracting a phase difference between the reference photocurrent signal and a corresponding frequency component of the detection echo photocurrent signal;

[0026] The rough delay directly obtained from the time domain and indirectly representing the distance of the link to be measured is optimized according to the time domain pulse quantity difference corresponding to the reference photocurrent signal and the detection echo photocurrent signal and the phase difference between the corresponding frequency components.

[0027] The integer ambiguity is obtained according to the optimized coarse time delay.

[0028] In a second aspect, the present invention provides a laser phase estimation device assisted by a single optical frequency comb, comprising:

[0029] a signal acquisition module, configured to acquire a detection optical signal and a reference optical signal corresponding to the detection optical signal, wherein both the detection optical signal and the reference optical signal are optical frequency comb signals;

[0030] A measurement module, configured to measure the spatial distance of the link to be measured using the detection optical signal to obtain a detection echo optical signal;

[0031] an intensity modulation module, configured to perform double-sideband intensity modulation on the reference optical signal and the detection echo optical signal using a single-frequency microwave signal;

[0032] a photoelectric conversion module, configured to perform beat frequency processing on the modulated reference optical signal and the modulated detection echo optical signal, respectively, to obtain a reference photocurrent signal and a detection echo photocurrent signal;

[0033] an analog-to-digital conversion module, configured to perform analog-to-digital conversion on the reference photocurrent signal and the detection echo photocurrent signal;

[0034] A solution module is used to calculate the frequency components of the modulated reference optical signal and the detection echo optical signal after the beat frequency in the digital domain, and

[0035] The phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal is defuzzified by using a time-combination method to obtain the precise spatial distance of the link to be measured.

[0036] Furthermore, the signal acquisition module includes:

[0037] An optical frequency comb source, used to generate an optical frequency comb signal;

[0038] an optical switch connected to the optical frequency comb and configured to perform gating processing on the re-frequency locked optical frequency comb signal;

[0039] A coupler is connected to the optical switch and is used to separate the selected optical frequency comb signal into the reference optical signal and the detection optical signal.

[0040] Furthermore, the device further comprises: a microwave source, wherein a reference input end of the microwave source is connected to the optical frequency comb source and the optical switch, and an output end of the microwave source is connected to the intensity modulation module.

[0041] Furthermore, the signal acquisition module, the microwave source, the analog-to-digital converter and the solution module are time-synchronized and locked.

[0042] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0043] The technical solution disclosed in the present invention can achieve high-precision and rapid ranging with a single optical frequency comb. By performing digital-to-analog conversion through a low-speed analog-to-digital converter, the requirements for data processing and the analog-to-digital converter are greatly reduced, and the ranging speed is greatly improved while ensuring the ranging range and accuracy. Compared with the traditional dual-optical frequency comb ranging solution, the technical solution disclosed in the present invention reduces the requirements for high-stability frequency locking, achieves lower implementation costs, and expands the unambiguous measurement range of a single optical comb. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of the process of the laser phase estimation method assisted by a single optical frequency comb disclosed in the present invention;

[0045] Figure 2 This is a schematic diagram of the module structure of the single optical frequency comb-assisted laser phase estimation device disclosed in the present invention;

[0046] Figure 3 This is a schematic structural diagram of a specific embodiment of the single optical frequency comb-assisted laser phase estimation device disclosed in the present invention. DETAILED DESCRIPTION

[0047] The technical solution of this invention enables high-precision and rapid ranging using a single optical frequency comb. Analog-to-digital conversion is performed using a low-speed analog-to-digital converter, significantly reducing the requirements for data processing and the converter. This significantly improves ranging speed while maintaining range and accuracy. Compared to traditional dual-optical frequency comb ranging solutions, this approach reduces the requirement for highly stable frequency locking, resulting in lower implementation costs and extending the unambiguous measurement range of a single optical comb.

[0048] like Figure 1 As shown, the laser phase estimation method assisted by a single optical frequency comb proposed in the present invention is specifically as follows:

[0049] S1. Acquire a detection light signal and a reference light signal corresponding to the detection light signal.

[0050] As described above, the probe and reference optical signals are split into two signals after being gated by the same optical frequency comb signal. In other words, both the probe and reference optical signals are optical frequency comb signals. The probe optical signal is used to measure the spatial distance of the link under test, while the reference optical signal serves as a reference for comparison. To obtain the probe and reference optical signals in this step, either pre-generated optical signals or generated optical signals can be directly acquired.

[0051] Regarding the method for generating an optical signal during measurement, in one embodiment, step S1 specifically includes:

[0052] S11, performing gating processing on the repetition-locked optical frequency comb signal;

[0053] S12. Split the selected optical frequency comb signal into a reference optical signal and a detection optical signal.

[0054] In the above, the optical frequency comb signal is first repetition-locked. This repetition-locking technique precisely controls the repetition frequency of the optical frequency comb signal, ensuring it remains stable. A specific signal is then selected and activated within the repetition-locked optical frequency comb signal. Finally, the selected signal is split into two optical signals: a reference signal and a probe signal.

[0055] S2. Use the detection optical signal to measure the spatial distance of the link to be measured to obtain a detection echo optical signal.

[0056] As mentioned above, the detection optical signal is mainly used to measure the spatial distance of the link to be measured. After the measurement, the detection echo optical signal obtained carries the time delay information introduced by the spatial link to be measured.

[0057] S3. Use a single-frequency microwave signal to perform double-sideband intensity modulation on the reference optical signal and the detection echo optical signal.

[0058] In the above description, double-sideband intensity modulation is performed on the reference optical signal and the probe echo optical signal, respectively, to obtain a modulated reference optical signal and a modulated probe echo optical signal. When performing intensity modulation, the higher the frequency of the single-frequency microwave signal, the higher the accuracy of the measurement result. Therefore, a high-frequency single-frequency microwave signal can be selected to perform double-sideband intensity modulation on the reference optical signal and the probe echo optical signal. Preferably, a high-frequency microwave signal greater than 40 GHz can be selected to perform double-sideband intensity modulation on the reference optical signal and the probe echo optical signal.

[0059] S4. Perform beat frequency processing on the modulated reference light signal and the detection echo light signal respectively to obtain a reference photocurrent signal and a detection echo photocurrent signal.

[0060] In the above, beat frequency processing is performed on the reference optical signal to convert the modulated reference optical signal into a reference photocurrent signal, and beat frequency processing is performed on the detection echo optical signal to convert the detection echo optical signal into a detection echo photocurrent signal.

[0061] S5. Perform analog-to-digital conversion on the reference photocurrent signal and the detection echo photocurrent signal.

[0062] In the above, the reference light data information is obtained by performing analog-to-digital conversion on the reference photocurrent signal, and the detection echo light data information is obtained by performing analog-to-digital conversion on the detection echo photocurrent signal.

[0063] S6. Calculate in the digital domain the frequency components of the modulated reference optical signal and the detection echo optical signal obtained by beating the frequency components.

[0064] As mentioned above, the optical frequency comb signal has equidistant comb teeth, and the comb teeth of the modulated optical signal have shifted compared to the optical signal before modulation. The so-called frequency component can be obtained based on the beat frequency between the comb teeth of the modulated optical signal and the comb teeth of the optical signal before modulation, and there can be multiple frequency components.

[0065] To reduce computational burden, embodiments of the present invention select only two low-frequency components, thereby lowering the hardware requirements for the photodetector and digital-to-analog converter during subsequent processing. For example, by beating the teeth of a modulated optical signal with the adjacent teeth of two pre-modulated optical signals, two distinct low-frequency components of the photocurrent signal can be obtained.

[0066] In one embodiment, step S6 specifically includes:

[0067] In the digital domain, a first frequency component obtained by the beat frequency between the comb teeth with the smallest spacing between the modulated reference optical signal and the reference optical signal before modulation, and a second frequency component obtained by the beat frequency with the second smallest spacing between the comb teeth are determined. In addition, a first frequency component obtained by the beat frequency between the comb teeth with the smallest spacing between the modulated detection echo optical signal and the detection echo optical signal before modulation, and a second frequency component obtained by the beat frequency with the second smallest spacing between the comb teeth are determined.

[0068] In the above, beat frequency processing is performed on the reference optical signal to convert the modulated reference optical signal into a reference photocurrent signal. Beat frequency processing is also performed on the detection echo optical signal to convert it into a detection echo photocurrent signal. The two lowest frequency components of the reference photocurrent signal are selected. Similarly, the two lowest frequency components of the detection photocurrent signal are selected to determine the two frequency components of the reference optical signal and the detection echo optical signal, respectively.

[0069] S7. Use the time-combined method to deambiguate the phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal to obtain the precise spatial distance of the link to be measured.

[0070] As mentioned above, in general, the delay introduced by the probe optical signal through the measured spatial link can be calculated by subtracting the delay of the reference link from the delay of the probe link, thereby further determining the distance of the measured spatial link. However, directly measuring the delay difference between the two in the time domain is insufficiently accurate, resulting in a coarse delay. The technical solution disclosed in this invention utilizes a time-dependent method to deambiguate the phase difference between the corresponding frequency components of the probe echo photocurrent signal and the reference photocurrent signal, determining the precise delay and thus calculating the distance of the measured spatial link.

[0071] In one embodiment, step S7 includes:

[0072] The integral ambiguity corresponding to the phase difference between the reference photocurrent signal and the corresponding frequency component of the detection echo photocurrent signal is calculated using the time-combination method.

[0073] Using integer ambiguity to optimize the coarse delay directly obtained from the time domain and indirectly representing the distance of the link to be measured;

[0074] Calculate the precise spatial distance of the link under test based on the precise time delay.

[0075] As mentioned above, if the reference photocurrent signal and the probe echo photocurrent signal each have two frequency components, then there are two phase differences between them. The integer ambiguity corresponds to the phase difference between the corresponding frequency components of the reference and probe echo photocurrent signals. The purpose of the time-combined method is to obtain more accurate integer ambiguities. This method utilizes the time delay information obtained in the time domain and the phase information obtained in the frequency domain to obtain a more precise coarse time delay, thereby obtaining accurate integer ambiguities.

[0076] In one embodiment, the time-combined method is used to calculate the integer ambiguity corresponding to the phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal, including:

[0077] The phase difference between the reference photocurrent signal and the corresponding frequency component of the detection echo photocurrent signal is extracted.

[0078] Optimizing the rough time delay directly obtained from the time domain and indirectly representing the distance of the link to be measured based on the difference in the number of time domain pulses corresponding to the reference photocurrent signal and the detection echo photocurrent signal and the phase difference between the corresponding frequency components;

[0079] Obtain the integer ambiguity based on the optimized coarse delay.

[0080] The coarse delay described above is introduced by the probe optical signal after measuring the spatial link under test. If both the reference photocurrent signal and the probe echo photocurrent signal have two frequency components, the reference photocurrent signal has a first frequency component and a second frequency component, and the probe echo photocurrent signal has a first frequency component and a second frequency component, the difference in the number of time-domain pulses between the two can be calculated in the time domain.

[0081] Exemplarily, the above steps specifically include:

[0082] Extracting a first phase difference between a first frequency component of the reference optical signal and a first frequency component of the detection echo optical signal, and a second phase difference between a second frequency component of the reference optical signal and a second frequency component of the detection echo optical signal;

[0083] Optimizing the rough delay introduced by the link to be tested based on the time domain pulse number difference, the first phase difference, and the second phase difference corresponding to the reference photocurrent signal and the detection echo optical signal;

[0084] The first integer ambiguity corresponding to the first phase difference is optimized according to the adjusted coarse delay.

[0085] As mentioned above, in this example, the first integer ambiguity corresponds to the first phase difference, the first phase difference corresponds to the first frequency component, the modulation signal frequency corresponding to the first frequency component is higher, and the frequency of the modulation signal is proportional to the accuracy, so it is chosen to optimize the first integer ambiguity.

[0086] The principle of the technical solution of the present invention is further described in detail below with specific examples:

[0087] The optical frequency comb signal E0(t) generated by the optical frequency comb source is expressed as:

[0088]

[0089] Among them, A nis the optical amplitude of the nth optical frequency comb signal. ceo is the frequency deviation of the optical frequency comb, f rep is the repetition frequency of the optical frequency comb. The optical frequency comb signal is then time-domain gated and divided into a detection optical signal and a reference optical signal. The detection optical signal is sent to the space link for ranging to obtain a detection echo optical signal. The expression of the detection echo optical signal can be written as:

[0090]

[0091] Where τ is the time delay generated during the ranging process, and α is the attenuation introduced by the space link.

[0092] The frequency is f RF The single-frequency microwave signal performs double-sideband intensity modulation on the received reference optical signal and the detection echo optical signal respectively, where the expression of the detection echo optical signal is:

[0093]

[0094] Where M is the electro-optical modulation coefficient.

[0095] The reference light signal and the detection echo light signal enter the photodetector for beat frequency processing, remove the DC component, and take the low-frequency component. The photocurrent corresponding to the obtained detection echo light signal is:

[0096]

[0097]

[0098] Where N1 represents the modulation signal f RF The number of comb teeth within the range. Define round(...) as the rounding symbol. The first sub-term in Equation (4) is the result of the beat frequency between the modulated signal and the original optical frequency comb signal closest to it (the first frequency component), and the second sub-term is the result of the beat frequency between the modulated signal and the original optical frequency comb signal closest to it (the second frequency component).

[0099] The beat signal is sent to the analog-to-digital converter, and the generated digital signal is input to the solution module to extract the phase difference between the reference link and the detection link corresponding to the two frequency components in formula (4): According to the characteristics of the optical frequency comb, the phase difference here is With frequency N1f rep and (N1-1)f rep The phase difference between the reference link and the detection link corresponding to the signal is equal, and the following expression can be obtained:

[0100]

[0101]

[0102] Among them, Defined as the floor symbol, N amb1 for The corresponding integer ambiguity, N amb2 for The corresponding integer ambiguity. The above formula (7) can be derived according to the definition of integer ambiguity. Taking the first formula in formula (6) as an example, substitute formula (7) into formula (6) and round down both sides to get:

[0103]

[0104] Where Δτ is the delay error of the oscilloscope, and it is valid if and only if |Δτ|<1 / (2N1f rep ), the above formula is valid. Due to the limited time accuracy of the oscilloscope, it is difficult to meet the above requirements, so it is necessary to use the phase method to further improve the coarse delay τ r The accuracy of , combined with equation (6) can be obtained:

[0105]

[0106] Where b = N amb1 -N amb2 , this difference can be determined based on the number of time domain pulses of the reference photocurrent signal corresponding to the gated reference optical signal and the detection echo photocurrent signal corresponding to the detection echo optical signal. After time domain gating, the time domain waveform of the optical frequency comb signal can be expressed as:

[0107]

[0108] Among them, n0 is the optical frequency comb signal corresponding to the time domain gating moment, A en The pulse width of (t) is t wid , when |t|>t wid / 2, A en (t) = 0. Then use the obtained τ r , calculate the exact N amb1 :

[0109]

[0110] Furthermore, N amb1 Substituting the first equation into equation (6), the exact delay τ can be calculated:

[0111]

[0112] Furthermore, the distance of the space link to be measured can be calculated:

[0113]

[0114] Among them, round(...) is defined as the rounding symbol; Defined as the rounding down sign; d is the distance of the space link to be measured; c is the speed of light; n air is the refractive index of air; f RF is the frequency of the single-frequency microwave signal; The first phase difference between the reference path and the detection path corresponding to the signal obtained by beating the modulated signal with the original optical frequency comb signal closest to it; is the second phase difference between the reference path and the detection path corresponding to the signal obtained by beating the modulation signal with the second closest original optical frequency comb signal; N amb1 for The corresponding first integer ambiguity, N amb2 for The corresponding second-whole-cycle ambiguity; f rep is the repetition rate of the optical frequency comb.

[0115] On the other hand, Figure 2 As shown, based on the single optical frequency comb assisted laser phase estimation method disclosed in the present invention, the single optical frequency comb assisted laser phase estimation device proposed in the present invention includes:

[0116] The signal acquisition module 201 is configured to acquire a detection optical signal and a reference optical signal corresponding to the detection optical signal.

[0117] The measurement module 202 is configured to measure the spatial distance of the link to be measured using the detection optical signal to obtain a detection echo optical signal.

[0118] The intensity modulation module 203 is configured to perform double-sideband intensity modulation on the reference optical signal and the detection echo optical signal using a single-frequency microwave signal.

[0119] The photoelectric conversion module 204 is used to perform beat frequency processing on the modulated reference light signal and the modulated detection echo light signal, respectively, to obtain a reference photocurrent signal and a detection echo photocurrent signal.

[0120] The analog-to-digital conversion module 205 is configured to perform analog-to-digital conversion on the reference photocurrent signal and the detection echo photocurrent signal.

[0121] The calculation module 206 is used to calculate the frequency components of the modulated reference optical signal and the detection echo optical signal respectively after the beat frequency in the digital domain, and

[0122] The phase difference between the reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal is defuzzified using the time-combination method to obtain the precise spatial distance of the link to be measured.

[0123] As mentioned above, the signal acquisition module 201 can be used to directly acquire an optical signal that has been generated before measurement, or to generate an optical signal, wherein both the detection optical signal and the reference signal are optical frequency comb signals.

[0124] In one embodiment, the signal acquisition module 201 includes:

[0125] An optical frequency comb source, used to generate an optical frequency comb signal;

[0126] An optical switch, connected to the optical frequency comb source, for gating the repetition-locked optical frequency comb signal;

[0127] The coupler is connected to the optical switch and is used to separate the selected optical frequency comb signal into a reference optical signal and a detection optical signal.

[0128] In one embodiment, the measurement module 202 includes: a circulator, a collimator, and a reflector, for measuring the spatial distance of the link to be measured.

[0129] In one embodiment, the intensity modulation module 203 performs double-sideband intensity modulation on the reference optical signal and the detection echo optical signal using a high-frequency microwave signal greater than 40 GHz.

[0130] In one embodiment, the solution module 206 includes:

[0131] A frequency component calculation module, used to respectively calculate the frequency components of the reference optical signal and the detection echo optical signal obtained by beating the frequency components;

[0132] The deambiguation module is used to deambiguate the phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal using a time-combined method to obtain the precise spatial distance of the link to be measured.

[0133] In one embodiment, the frequency component calculation module in the solution module 206 is specifically configured to:

[0134] In the digital domain, a first frequency component obtained by the beat frequency between the comb teeth with the smallest spacing between the reference optical signal after modulation and the reference optical signal before modulation and a second frequency component obtained by the beat frequency with the second smallest spacing between the comb teeth are determined, as well as a first frequency component obtained by the beat frequency between the comb teeth with the smallest spacing between the detection echo optical signal after modulation and the detection echo optical signal before modulation and a second frequency component obtained by the beat frequency with the second smallest spacing between the comb teeth are determined.

[0135] In one embodiment, the defuzzification module in the solution module 206 includes:

[0136] An integer ambiguity calculation module is used to calculate the integer ambiguity corresponding to the phase difference between the reference photocurrent signal and the corresponding frequency component of the detection echo photocurrent signal using a time-combined method;

[0137] An accurate time delay calculation module is used to calculate the accurate time delay introduced by the space link to be measured in the detection echo optical signal using the integer ambiguity;

[0138] The spatial distance calculation module is used to calculate the precise spatial distance of the link to be tested based on the precise delay.

[0139] In one embodiment, the integer ambiguity calculation module is specifically configured to:

[0140] Extracting the phase difference between the reference photocurrent signal and the corresponding frequency component of the detection echo photocurrent signal;

[0141] Optimizing the rough time delay directly obtained from the time domain and indirectly representing the distance of the link to be measured based on the difference in the number of time domain pulses corresponding to the reference photocurrent signal and the detection echo photocurrent signal and the phase difference between the corresponding frequency components;

[0142] The whole-cycle ambiguity is obtained based on the optimized coarse delay difference.

[0143] In one embodiment, the apparatus disclosed in the embodiment of the present invention further includes:

[0144] A microwave source, a reference input end of the microwave source is connected to the optical frequency comb source and the optical switch, and an output end of the microwave source is connected to the intensity modulation module.

[0145] In one embodiment, the signal acquisition module 201 , the microwave source, the analog-to-digital converter and the solution module 206 are time-synchronized and locked to ensure time synchronization among the signal acquisition module 201 , the microwave source, the analog-to-digital converter and the solution module 206 .

[0146] For ease of understanding, the technical solution of the present invention is described in detail below through a specific embodiment with reference to the accompanying drawings:

[0147] like Figure 3As shown, the single optical frequency comb-assisted laser phase estimation device of this embodiment includes: an optical frequency comb source, an optical switch, a coupler, a local oscillator source, a single-frequency microwave source, two intensity modulators, two photodetectors, a dual-channel analog-to-digital converter, and a resolution module. The output of the local oscillator source is connected to the optical frequency comb source, the optical switch, the microwave source, the analog-to-digital converter, and the resolution module. The local oscillator source is used to provide a unified reference for the modules connected to it. The output of the optical frequency comb source is connected to the optical switch, the output of the optical switch is connected to the coupler, the output of the coupler is connected to a circulator and an intensity modulator, and the output of the circulator is connected to another intensity modulator and a collimator. The output of the microwave source is connected to a power splitter, the output of the power splitter is connected to two intensity modulators, respectively. The outputs of the two intensity modulators are connected to two photodetection modules, respectively. The outputs of the two photodetection modules are connected to a dual-channel analog-to-digital converter, and the output of the analog-to-digital converter is connected to the input of the resolution module.

[0148] As described above, the optical frequency comb source outputs a continuous optical frequency comb signal, whose repetition rate is referenced by a highly stable local oscillator (LO) to achieve repetition rate locking of the optical frequency comb. The generated signal is then selected by an optical switch and input into a coupler, where it is split into two paths: one serving as the reference optical signal and the other as the detection optical signal. This signal enters a circulator and is collimated to measure spatial distance, generating a detection echo optical signal. The reference optical signal and the detection echo optical signal, which carries spatial distance delay information, are then input into two intensity modulators. Double-sideband intensity modulation is performed on the two optical frequency comb signals using a single-frequency microwave signal. Two photodetectors perform beat frequency processing on the reference optical signal and the detection echo optical signal, respectively, to generate two photocurrent signals. These two photocurrent signals are converted by a dual-channel analog-to-digital converter. The phase difference and the gating time difference between the corresponding frequency components of the reference optical signal and the detection echo optical signal are calculated in the digital domain. A time-dependent combination method is then used to gradually calculate the precise spatial distance of the link under test. The above process requires locking the optical switch, single-frequency microwave source, solution module, analog-to-digital converter and optical frequency comb source to ensure signal synchronization.

Claims

1. A laser phase estimation method assisted by a single optical frequency comb, characterized in that: include: Acquire a detection optical signal and a reference optical signal corresponding to the detection optical signal, wherein both the detection optical signal and the reference optical signal are optical frequency comb signals; Using the detection optical signal to measure the spatial distance of the link to be measured, to obtain a detection echo optical signal; Performing double-sideband intensity modulation on the reference optical signal and the detection echo optical signal using a single-frequency microwave signal; performing beat frequency processing on the modulated reference optical signal and the modulated detection echo optical signal respectively to obtain a reference photocurrent signal and a detection echo photocurrent signal; Performing analog-to-digital conversion on the reference photocurrent signal and the detection echo photocurrent signal; respectively calculating in a digital domain the frequency components of the modulated reference optical signal and the detection echo optical signal obtained by beating the frequency components; The phase difference between the reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal is defuzzified by using a time-combination method to obtain the precise spatial distance of the link to be measured.

2. The laser phase estimation method assisted by a single optical frequency comb according to claim 1, wherein: The acquiring of the detection light signal and the reference light signal corresponding to the detection light signal includes: Performing gating processing on the repetition-locked optical frequency comb signal; The gated optical frequency comb signal is divided into the reference optical signal and the detection optical signal.

3. The laser phase estimation method assisted by a single optical frequency comb according to claim 1, wherein: The performing double-sideband intensity modulation on the reference optical signal and the detection echo optical signal by using a single-frequency microwave signal comprises: The reference optical signal and the detection echo optical signal are subjected to double-sideband intensity modulation using a high-frequency microwave signal greater than 40 GHz.

4. The laser phase estimation method assisted by a single optical frequency comb according to claim 1, wherein: The step of respectively calculating in the digital domain the frequency components of the modulated reference optical signal and the detection echo optical signal obtained by beating the frequency components includes: In the digital domain, a first frequency component obtained by the beat frequency between the comb teeth at which the spacing between the reference optical signal after modulation and the reference optical signal before modulation is the smallest and a second frequency component obtained by the beat frequency with the second smallest comb tooth spacing are determined, as well as a first frequency component obtained by the beat frequency between the comb teeth at which the spacing between the detection echo optical signal after modulation and the detection echo optical signal before modulation is the smallest and a second frequency component obtained by the beat frequency with the second smallest comb tooth spacing are determined.

5. The laser phase estimation method assisted by a single optical frequency comb according to claim 1, wherein: The method of using a time-combined method to deambiguate the phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal to obtain the precise spatial distance of the link to be measured includes: Calculating the integer ambiguity corresponding to the phase difference between the reference photocurrent signal and the corresponding frequency component of the detection echo photocurrent signal using a time-combined method; Calculating the precise time delay introduced by the spatial link to be measured using the integer ambiguity; The precise spatial distance of the link to be measured is calculated according to the precise time delay.

6. The single optical frequency comb assisted laser phase estimation method according to claim 5, characterized in that: The method of calculating the integer ambiguity corresponding to the phase difference between the reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal by using the time-combined method includes: Extracting a phase difference between the reference photocurrent signal and a corresponding frequency component of the detection echo photocurrent signal; Optimizing the rough time delay directly obtained from the time domain and indirectly representing the distance of the link to be measured based on the time domain pulse number difference corresponding to the reference photocurrent signal and the detection echo photocurrent signal and the phase difference between the corresponding frequency components; The integer ambiguity is obtained according to the optimized coarse time delay.

7. A laser phase estimation device assisted by a single optical frequency comb, characterized in that: include: a signal acquisition module, configured to acquire a detection optical signal and a reference optical signal corresponding to the detection optical signal, wherein both the detection optical signal and the reference optical signal are optical frequency comb signals; A measurement module, configured to measure the spatial distance of the link to be measured using the detection optical signal to obtain a detection echo optical signal; an intensity modulation module, configured to perform double-sideband intensity modulation on the reference optical signal and the detection echo optical signal using a single-frequency microwave signal; a photoelectric conversion module, configured to perform beat frequency processing on the modulated reference optical signal and the modulated detection echo optical signal, respectively, to obtain a reference photocurrent signal and a detection echo photocurrent signal; An analog-to-digital conversion module, configured to perform analog-to-digital conversion on the reference photocurrent signal and the detection echo photocurrent signal; A calculation module is used to calculate the frequency components of the modulated reference optical signal and the detection echo optical signal obtained by beating the frequency in the digital domain, and The phase difference between the reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal is defuzzified by using a time-combination method to obtain the precise spatial distance of the link to be measured.

8. The laser phase estimation device assisted by a single optical frequency comb according to claim 7, characterized in that: The signal acquisition module includes: An optical frequency comb source, used to generate an optical frequency comb signal; an optical switch connected to the optical frequency comb and configured to perform gating processing on the re-frequency locked optical frequency comb signal; A coupler is connected to the optical switch and is used to separate the selected optical frequency comb signal into the reference optical signal and the detection optical signal.

9. The laser phase estimation device assisted by a single optical frequency comb according to claim 8, characterized in that: The device further includes: a microwave source, wherein a reference input end of the microwave source is connected to the optical frequency comb source and the optical switch, and an output end of the microwave source is connected to the intensity modulation module.

10. The single optical frequency comb assisted laser phase estimation device according to claim 9, characterized in that: The signal acquisition module, the microwave source, the analog-to-digital conversion module and the solution module are time-synchronized and locked.

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