Laser phase distance measurement method and device assisted by single optical frequency comb

Abstract

The invention discloses a laser phase distance measurement method and device assisted by a single optical frequency comb. The method comprises the following steps: acquiring a detection light signal and a reference light signal; measuring the spatial distance of the to-be-measured link by 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 by using the single-frequency microwave signal; performing beat frequency processing on the modulated reference light signal and the modulated detection echo light signal to obtain a reference light current signal and a detection echo light current signal; performing analog-to-digital conversion on the reference light current signal and the detection echo light current signal; respectively calculating frequency components obtained by beat frequency of the reference light signal and the detection echo light signal; and defuzzifying the phase difference between the corresponding frequency components of the reference light current signal and the detection echo light current signal to obtain the accurate spatial distance of the link to be detected. According to the invention, the distance measurement speed is greatly improved under the condition that the distance measurement range and precision are ensured.

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 with good monochromaticity, strong directionality and high ranging accuracy. It is widely used in defense, construction, aerospace and engineering measurement. Among the commonly used ranging methods, the pulse method calculates the target distance by directly measuring the time difference between the transmitted pulse and the received pulse. It has a fast measurement speed and a range of up to thousands of meters, but the ranging accuracy is limited by the width of the pulse and can only reach the millimeter level at most. The frequency scanning interferometer method obtains the time delay information at the interference frequency through continuous linear frequency sweeping of the laser to calculate the target distance, but it is limited by the laser frequency tuning speed and subsequent algorithm processing, resulting in a slow measurement speed. The phase method indirectly calculates the target distance based on the phase difference generated by the modulated light wave going back and forth to the measured distance. Its ranging accuracy depends on high-frequency signals, requires high-performance detectors and high-speed ADCs, has a large amount of processor calculations, and has a high hardware cost for the system. In addition, since the phase obtained by the phase detector has 2π ambiguity, the phase push method is often used to solve this problem, which requires modulating a series of microwave signals for phase unwrapping, thereby limiting its measurement speed. Optical frequency combs have become a new type of measurement method with their ultra-high frequency stability, good coherence and wide spectrum range, bringing new ideas and methods to the development of traditional absolute distance measurement technology. For example, the traditional dual-comb distance measurement method requires locking the repetition frequency and absolute frequency of the two frequency combs, which makes the system more complex and expensive.

[0003] In summary, the 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 ADC and slow ranging speeds; the traditional dual-optical frequency comb ranging system is 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 ranging method and device assisted by a single optical frequency comb, so as to realize high-precision and rapid ranging of 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 light signal and a reference light signal corresponding to the detection light signal, wherein both the detection light signal and the reference light 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 light signal and the modulated detection echo light 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] In the digital domain, frequency components of the modulated reference optical signal and the detection echo optical signal obtained by beating the frequency components are calculated respectively;

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

[0013] Further, the acquiring of the detection light signal and a reference light signal corresponding to the detection light signal comprises:

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

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

[0016] Furthermore, 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:

[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 after beating, comprises:

[0019] Determine in the digital domain the 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 the second frequency component obtained by the beat frequency with the second smallest comb tooth spacing, as well as determine the 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 the second frequency component obtained by the beat frequency with the second smallest comb tooth spacing.

[0020] Furthermore, the time-combination method is used to deambiguate the phase difference between the reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal to obtain the spatial distance of the link to be measured, including:

[0021] 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 by using a time combination 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 time-combined method 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, including:

[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, used 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, used 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, used for performing 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, used for performing beat frequency processing on the modulated reference light signal and the modulated detection echo light signal to obtain a reference photocurrent signal and a detection echo photocurrent signal;

[0033] An analog-to-digital conversion module, used for performing analog-to-digital conversion on the reference photocurrent signal and the detection echo photocurrent signal;

[0034] A calculation 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 reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal is deambiguated 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 for generating an optical frequency comb signal;

[0038] an optical switch connected to the optical frequency comb and used for gating the repetition-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 also includes: 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.

[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 realize high-precision and rapid ranging of 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, has a lower implementation cost, and expands the unambiguous measurement range of a single optical comb. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a 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 It is a schematic diagram of the module structure of the laser phase estimation device assisted by a single optical frequency comb disclosed in the present invention;

[0046] Figure 3 The figure 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 the present invention can achieve high-precision and fast ranging of a single optical frequency comb, and can perform analog-to-digital conversion through a low-speed analog-to-digital converter, greatly reducing the requirements for data processing and analog-to-digital converters, and greatly improving the ranging speed while ensuring the ranging range and accuracy. Compared with the traditional dual-optical frequency comb ranging solution, it reduces the requirements for high-stability frequency locking, has a lower implementation cost, and expands 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 detection optical signal and the reference optical signal are two signals divided by the same optical frequency comb signal after selection, that is, the detection optical signal and the reference optical signal are both optical frequency comb signals. The detection optical signal is used to measure the spatial distance of the link to be measured, and the reference optical signal is used as a reference for comparison. In this step, the detection optical signal and the reference optical signal are obtained, and the optical signal generated before the measurement can be directly collected, or an optical signal can be generated.

[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-frequency locked optical frequency comb signal;

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

[0054] As mentioned above, the optical frequency comb signal is first repetition locked. The purpose of repetition locking is to precisely control the repetition frequency of the optical frequency comb signal and keep it stable. Then, a specific signal is selected and activated in the repetition locked optical frequency comb signal. Finally, the selected signal is divided into two optical signals, namely the reference optical signal and the detection optical 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, the reference optical signal and the detection echo optical signal are subjected to double-sideband intensity modulation respectively to obtain the modulated reference optical signal and the modulated detection 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 here to perform double-sideband intensity modulation on the reference optical signal and the detection 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 detection 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, the reference light signal is subjected to beat frequency processing to convert the modulated reference light signal into a reference photocurrent signal, and the detection echo light signal is subjected to beat frequency processing to convert the detection echo light 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 with 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] In order to reduce the computational pressure, the embodiment of the present invention can select only two low-frequency components, thereby reducing the hardware requirements for the photodetector and the digital-to-analog converter in subsequent processing. Taking a comb tooth of a modulated optical signal as an example, the comb teeth of two optical signals before modulation are adjacent to it. The comb teeth of the modulated optical signal beat the comb teeth of the two adjacent optical signals before modulation, and two different low-frequency components in the photocurrent signal can be obtained.

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

[0067] In the digital domain, determine the first frequency component obtained by the beat frequency between the comb teeth with the smallest spacing between the modulated reference light signal and the reference light signal before modulation, and the second frequency component obtained by the beat frequency with the second smallest comb tooth spacing, and determine the first frequency component obtained by the beat frequency between the comb teeth with the smallest spacing between the modulated detection echo light signal and the detection echo light signal before modulation, and the second frequency component obtained by the beat frequency with the second smallest comb tooth spacing.

[0068] In the above, the reference light signal is subjected to beat frequency processing, and the modulated reference light signal is converted into a reference photocurrent signal. The detection echo light signal is subjected to beat frequency processing, and the detection echo light signal is converted into a detection echo photocurrent signal. The two lowest frequency components in the reference photocurrent signal are selected. Similarly, the two lowest frequency components in the detection photocurrent are selected, thereby respectively determining the two frequency components of the reference light signal and the detection echo light signal.

[0069] S7. Use the time-combined method to deambiguate the phase difference between the reference photocurrent signal and the corresponding frequency components of 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 of the detection link minus the delay of the reference link can be used to obtain the delay introduced by the detection optical signal passing through the space link to be measured, thereby further obtaining the distance of the space link to be measured. However, directly measuring the delay difference between the two in the time domain does not provide a rough delay due to its insufficient delay accuracy. The technical solution disclosed in the present invention uses a time-combined method to deambiguate the phase difference of the corresponding frequency components of the detection echo photocurrent signal and the reference photocurrent signal, determine the precise delay, and then calculate the distance of the space link to be measured.

[0071] In one embodiment, step S7 includes:

[0072] The integer ambiguity corresponding to the phase difference between the reference photocurrent signal and the corresponding frequency component of the detection echo photocurrent signal is calculated by 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 to be tested based on the precise delay.

[0075] As mentioned above, if the reference photocurrent signal and the detection echo photocurrent signal both have two frequency components, there are two phase differences between the reference photocurrent signal and the detection echo photocurrent signal. The integer ambiguity corresponds to the phase difference between the corresponding frequency components of the reference photocurrent signal and the detection echo photocurrent signal. The purpose of the time combination method is to obtain more accurate integer ambiguity, using the time delay information obtained from the time domain and the phase information obtained from the frequency domain to obtain a more accurate coarse time delay, thereby obtaining accurate integer ambiguity.

[0076] In one embodiment, the integer ambiguity corresponding to the phase difference between the reference photocurrent signal and the corresponding frequency component of the detection echo photocurrent signal is calculated by using a time combination method, 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 delay directly obtained from the time domain and indirectly representing the distance of the link to be measured according to 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] The integer ambiguity is obtained based on the optimized coarse delay.

[0080] As mentioned above, the rough delay is introduced by the detection optical signal after measuring the space link to be measured. If the reference photocurrent signal and the detection echo photocurrent signal both have two frequency components, the reference photocurrent signal has a first frequency component and a second frequency component, and the detection echo photocurrent signal has a first frequency component and a second frequency component. In the time domain, the difference in the number of time domain pulses between the two can be calculated.

[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 according to the time domain pulse quantity difference and 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 relatively high, 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 light 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. Then the optical frequency comb signal is time-domain gated, and then the gated optical frequency comb signal is 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] Among them, τ is the delay generated in 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. The expression of the detection echo optical signal is:

[0093]

[0094] Where M is the electro-optic 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 in the range. Define round(...) as the rounding symbol. The first sub-formula 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-formula 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 signal after the beat frequency is sent to the analog-to-digital converter, and the generated digital signal is input into the solution module to extract the phase difference between the reference link and the detection link corresponding to the two frequency components in equation (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 sign, N amb1 for The corresponding integer ambiguity, N amb2 for The corresponding integer ambiguity. The above formula (7) can be obtained 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 of the formula to get:

[0103]

[0104] Where Δτ is the delay error of the oscilloscope, if and only if |Δτ|<1 / (2N1f rep ), the above formula is valid. Since the time accuracy of the oscilloscope is limited and it is difficult to meet the above requirements, it is necessary to adopt 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 reference light signal after gating and the detection echo photocurrent signal corresponding to the detection echo light 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 in (6), the exact delay τ can be calculated:

[0111]

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

[0113]

[0114] Among them, round(...) is defined as the rounding symbol; Defined as the round-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 the beat frequency between the modulated signal and 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 the beat frequency between the modulated signal and the original optical frequency comb signal that is the second closest to it; N amb1 for The corresponding first integer ambiguity, N amb2 for The corresponding second integer ambiguity; f rep is the repetition frequency 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 used to acquire a detection optical signal and a reference optical signal corresponding to the detection optical signal.

[0117] The measuring module 202 is used to measure the spatial distance of the link to be measured by using the detection optical signal to obtain the detection echo optical signal.

[0118] The intensity modulation module 203 is used 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 used 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 component of the detection echo photocurrent signal is deambiguated 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 collect the optical signal that has been generated before the measurement, and can also be used to generate the optical signal, wherein the detection optical signal and the reference signal are both optical frequency comb signals.

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

[0125] An optical frequency comb source, used for generating an optical frequency comb signal;

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

[0127] A 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, which are used to measure 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 reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal by using a time combination method to obtain the precise spatial distance of the link to be measured.

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

[0134] In the digital domain, determine the 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 the second frequency component obtained by the beat frequency with the second smallest comb tooth spacing, and determine the 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 the second frequency component obtained by the beat frequency with the second smallest comb tooth spacing.

[0135] In one embodiment, in the solution module 206, the defuzzification module 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 by using a time combination method;

[0137] An accurate time delay calculation module, used to calculate the accurate time delay introduced by the space link to be measured in the detection echo optical signal by 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 used 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 delay directly obtained from the time domain and indirectly representing the distance of the link to be measured according to 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 integer ambiguity is obtained based on the optimized coarse delay difference.

[0143] In one embodiment, the device 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 in conjunction with the accompanying drawings:

[0147] like Figure 3As shown, the laser phase estimation device assisted by a single optical frequency comb in 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. Among them, the output end 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, and the local oscillator source is used to provide a unified reference for the modules connected thereto. The output end of the optical frequency comb source is connected to the optical switch, the output end of the optical switch is connected to the coupler, the output end of the coupler is connected to a circulator and an intensity modulator, and the output end of the circulator is connected to another intensity modulator and a collimator. The output end of the microwave source is connected to the power divider, and the output end of the power divider is respectively connected to two intensity modulators. The output ends of the two intensity modulators are respectively connected to two photodetection modules. The output ends of the two photodetection modules are connected to the dual-channel analog-to-digital converter, and the output end of the analog-to-digital converter is connected to the input end of the resolution module.

[0148] As mentioned above, the optical frequency comb source outputs a continuous optical frequency comb signal, and its repetition frequency is used as a frequency reference by a high-stability local oscillator source to achieve repetition frequency locking of the optical frequency comb. The generated signal is input into the coupler after being selected by the optical switch and is divided into two paths, one as a reference optical signal, and the other as a detection optical signal. It enters the circulator through a collimator to measure the spatial distance and form a detection echo optical signal. After that, the reference optical signal and the detection echo optical signal carrying the spatial distance delay information are respectively input into two intensity modulators, and the two optical frequency comb signals are subjected to double-sideband intensity modulation 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 obtain two photocurrent signals. The two photocurrent signals are converted by a dual-channel analog-to-digital converter, and the phase difference and the time difference of the selection between the corresponding frequency components of the reference optical signal and the detection echo optical signal are solved in the digital domain. The precise spatial distance of the link to be measured is gradually solved using the time combination method. 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 light signal and a reference light signal corresponding to the detection light signal, wherein both the detection light signal and the reference light 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 light signal and the modulated detection echo 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; In the digital domain, frequency components of the modulated reference optical signal and the detection echo optical signal obtained by beating the frequency components are calculated respectively; The phase difference between the reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal is deambiguated 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 as claimed in claim 1, characterized in that: The acquiring of the detection light signal and the reference light signal corresponding to the detection light signal comprises: Perform gating processing on the repetition-locked optical frequency comb signal; The selected 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 as claimed in claim 1, characterized in that: The method of 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 as claimed in claim 1, characterized in that: 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 comprises: Determine in the digital domain the 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 the second frequency component obtained by the beat frequency with the second smallest comb tooth spacing, as well as determine the 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 the second frequency component obtained by the beat frequency with the second smallest comb tooth spacing.

5. The laser phase estimation method assisted by a single optical frequency comb as claimed in claim 1, characterized in that: The method of using the time-combination method to deambiguate the phase difference between the reference photocurrent signal and the corresponding frequency components of the detection echo photocurrent signal to obtain the precise spatial distance of the link to be measured includes: 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 by using a time combination 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 component of the detection echo photocurrent signal by using the time combination method includes: Extracting a phase difference between the reference photocurrent signal and a corresponding frequency component of the detection echo photocurrent signal; 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. 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, used 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, used 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, used for performing 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, used for performing beat frequency processing on the modulated reference light signal and the modulated detection echo light signal to obtain a reference photocurrent signal and a detection echo photocurrent signal; An analog-to-digital conversion module, used for performing 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 respectively after the beat 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 deambiguated 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 as claimed in claim 7, characterized in that: The signal acquisition module comprises: An optical frequency comb source, used for generating an optical frequency comb signal; an optical switch connected to the optical frequency comb and used for gating the repetition-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 as claimed in claim 8, characterized in that: 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.

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

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