Real-time representation device for ghz pulse repetition frequency based on dual-optical-comb spectroscopy

Abstract

Disclosed is a real-time representation device for the GHz pulse repetition frequency based on dual-optical-comb spectroscopy. The device comprises a signal optical comb light source, a first polarization controller, a polarization beam splitter, a local oscillator optical comb light source, a first optical coupler, a second optical coupler, a first photoelectric detector, a third optical coupler, a second photoelectric detector, a high-speed oscilloscope, and a data processing module; real-time measurement of GHz pulse repetition frequency dynamics is realized; dual-optical-comb spectroscopy measurement technology is used to carry out real-time measurement on the spectral characteristics of the GHz pulse repetition frequencies of different soliton types; and the device has the advantages of high spectral resolution, high refresh rate, system integration, and the like, and solves the problems of the soliton evolution phenomenon of optical fiber lasers of special wavebands such as 2 μm, and transient changes of GHz pulse repetition frequency dynamics being difficult to effectively represent by means of a traditional average measurement method, and the like.

Description

GHz repetition rate pulse real-time characterization device based on dual-comb spectroscopy TECHNICAL FIELD

[0001] The application belongs to the technical field of optical frequency comb, and particularly relates to a GHz repetition rate pulse real-time characterization device based on dual-comb spectroscopy. BACKGROUND

[0002] As a mature ultra-short pulse source, ultrafast fiber lasers play a vital role in the fields of optical communication, material processing and basic scientific research. In addition, ultrafast fiber lasers usually generate soliton pulses, which provide an ideal experimental platform for studying various soliton dynamics and nonlinear phenomena. Due to manufacturing defects and inevitable fiber bending, single-mode fiber has a certain degree of birefringence characteristics and supports the transmission of two orthogonal polarization modes. Among the two orthogonal polarization modes, the pulse transmission has different phase and group velocity. Therefore, according to the amount of intracavity birefringence and the coupling strength between the two orthogonal polarization components, different types of vector solitons can be observed in the ultrafast fiber laser based on single-mode fiber, such as polarization-rotating vector solitons and group-velocity-locked vector solitons. In the polarization-rotating vector solitons, the pulse intensity along the two polarization components shows changes between several values in the laser output, and can be locked to the intracavity round-trip time or its multiple. In the group-velocity-locked vector solitons, the two orthogonal polarization components capture each other by moving the center wavelength to offset the intracavity birefringence, so as to propagate at the same group velocity. In addition, solitons interact with each other through various mechanisms, and also form different types of multi-soliton complexes, such as soliton clusters, soliton rain, soliton molecules and various coexistence states. In particular, high repetition rate (>1 GHz) mode-locked fiber lasers have the characteristics of short pulse interval and large longitudinal mode spacing, but the evolution of vector soliton pulse dynamics is still unclear. In the past research, the characterization of soliton pulses is mainly realized by conventional detection instruments such as traditional spectrum analyzers and autocorrelators. However, due to the limitation of response speed, these measuring instruments show the results after averaging processing, rather than real-time measurement results, which means that some important information may be ignored. Therefore, how to realize the real-time observation of the characteristics of ultrafast pulse solitons is a major challenge to be overcome.

[0003] The dispersion Fourier transform technique provides an effective method for real-time measurement of soliton spectral information. With sufficient dispersion, the dispersion Fourier transform technique can map the spectrum of an optical pulse onto a time waveform, allowing an optoelectronic detector to capture spectral information. This technique can capture information at a faster scanning rate than traditional spectrum analyzers through a high-speed real-time oscilloscope and has been used to observe the transient dynamics of solitons, such as "Dynamic trapping of a polarization rotation vector soliton in a fiber laser", which real-time observed the polarization rotation vector soliton characteristics of a 1.5 μm low repetition rate mode-locked fiber laser. In addition, in the existing patent high-resolution real-time ultra-short pulse time-frequency domain measurement device and method (CN201910458893.7), the dispersion Fourier transform technique is used to realize real-time measurement of the sub-picosecond transient characteristics of ultra-short pulses. However, most dispersion Fourier transform techniques are designed for fiber laser systems in the 1 μm-1.5 μm wavelength band. Since commercial single-mode optical fibers have high propagation loss at wavelengths greater than 2 μm, it is not ideal to use the dispersion Fourier transform technique to measure soliton dynamics at 2 μm. In addition, time imaging techniques using time lenses have also been used to study the soliton characteristics of ultrafast lasers. Unfortunately, for pulses with a repetition rate greater than 1 GHz, this technique has certain limitations in terms of recording length or pulse resolution. In particular, in the 2 μm wavelength band, the time lens technique can be limited by the availability of phase modulators, thereby affecting its feasibility in practical applications. Recently, dual-comb spectroscopy measurement techniques have attracted widespread attention due to their high spectral resolution and high refresh rate characteristics, providing an important tool for various applications such as optical imaging, gas molecule measurement, and capturing transient events. Therefore, based on dual-comb spectroscopy measurement techniques, it is expected to realize real-time measurement of the soliton characteristics of GHz repetition rate pulses, revealing transient phenomena that are difficult to characterize by traditional average measurement techniques. SUMMARY

[0004] In order to overcome the shortcomings of the prior art described above, the purpose of the present application is to provide a GHz repetition rate pulse real-time characterization device based on dual-comb spectroscopy, which controls the birefringence of the intracavity fiber by adjusting the intracavity polarization controller of the signal comb, to realize the state switching of different types of vector solitons. A GHz repetition rate dual-comb spectroscopy measurement system is constructed by heterodyne frequency mixing with an intrinsic comb with a wide spectral range and a slightly different repetition rate, and is used for real-time measurement of the soliton characteristics of GHz repetition rate pulses.

[0005] The purpose of the present application is achieved at least by one of the following technical solutions.

[0006] A GHz repetition frequency pulse real-time characterization device based on dual-comb spectroscopy, comprising a signal comb light source, a first polarization controller, a polarization beam splitter, a local comb light source, a first optical coupler, a second optical coupler, a first photodetector, a third optical coupler, a second photodetector, a high-speed oscilloscope and a data processing module;

[0007] The output end of the signal comb light source is sequentially connected with the first polarization controller and the polarization beam splitter to resolve two orthogonal polarization components of the vector soliton and input the second optical coupler and the third optical coupler respectively; the output of the local comb light source is split by the first optical coupler and then recombined with the two orthogonal polarization components in the second optical coupler and the third optical coupler respectively, and then the beat frequency interference is carried out in the first photodetector and the second photodetector respectively; the output ends of the first photodetector and the second photodetector are connected with the high-speed oscilloscope, and the beat frequency interference results of the first photodetector and the second photodetector are displayed as time-domain interferograms in the high-speed oscilloscope; the high-speed oscilloscope collects the displayed time-domain interferograms and carries out data processing in the data processing module to measure the spectral characteristics of different soliton type GHz repetition frequency pulses output by the signal comb light source in real time.

[0008] Further, the polarization beam splitter has two optical fiber output ends to separate the two orthogonal polarization components of the vector soliton.

[0009] Further, the local comb light source has a wider spectral range than the signal comb light source and maintains linear polarization output.

[0010] Further, the splitting ratios of the first optical coupler, the second optical coupler and the third optical coupler are all 1:1.

[0011] Further, the data processing module carries out Fourier transform processing on the time-domain interferograms to obtain real-time spectral characteristics.

[0012] Further, the signal comb light source comprises a piezoelectric actuator, a semiconductor saturable absorber mirror, a second polarization controller, a gain optical fiber, a dielectric film, a ferrule, a wavelength division multiplexer, a pump source, an isolator, a fourth optical coupler, a carrier envelope offset frequency locking module and a repetition frequency locking module.

[0013] The middle part of the gain optical fiber passes through the second polarization controller, and the two ends are respectively connected with the semiconductor saturable absorber mirror and the front surface of the dielectric film; the back surface of the semiconductor saturable absorber mirror is pasted on the piezoelectric actuator, and the dielectric film is plated on the end face of the ferrule; the pump end of the wavelength division multiplexer is connected with the pump source, the common end is connected with the tail fiber of the ferrule, and the signal end is connected with the isolator; the signal light output through the isolator is connected with the fourth optical coupler to divide into three beams of light, the first beam of light is connected with the carrier envelope offset frequency locking module, and is fed back to the pump source to realize carrier envelope offset frequency locking; the second beam of light is connected with the repetition frequency locking module, and is fed back to the piezoelectric actuator to realize repetition frequency locking; and the third beam of light is directly output.

[0014] Further, the signal light comb light source adopts devices of a polarization-independent type, that is, the polarization direction is allowed to change randomly.

[0015] Further, the splitting ratio of the fourth optical coupler is 1:1:1.

[0016] Further, the carrier envelope offset frequency locking module detects the carrier envelope offset frequency of the signal light, and feeds back the jitter error signal to the pump source to adjust the pump power and realize carrier envelope offset frequency locking.

[0017] Further, the repetition frequency locking module detects the repetition frequency of the signal light, and feeds back the jitter error signal to the piezoelectric actuator to change the length of the resonant cavity and realize repetition frequency locking.

[0018] Compared with the prior art, the advantages of the present application are that:

[0019] The present application provides a GHz repetition frequency pulse real-time characterization device based on double-comb spectroscopy, which uses double-comb spectroscopy measurement technology to realize real-time measurement of the spectral characteristics of GHz repetition frequency pulses of different soliton types, has the advantages of high spectral resolution, high refresh rate and system integration, and solves the problems that the traditional average measurement method cannot effectively characterize the soliton evolution phenomenon of special waveband fiber lasers such as 2 mu m, the transient changes of GHz repetition frequency pulse dynamics, etc. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 is a structure schematic diagram of a GHz repetition frequency pulse real-time characterization device based on double-comb spectroscopy provided by the embodiment of the present application;

[0021] Fig. 2 is a structure schematic diagram of a signal light comb light source provided by the embodiment of the present application;

[0022] Fig. 3 is an output spectrum diagram of a GHz repetition frequency double-comb provided by the embodiment of the present application;

[0023] Fig. 4 is a group velocity locking vector soliton real-time spectrum feature map tested by a GHz repetition frequency pulse real-time characterization device provided by an embodiment of the present application based on double optical comb spectroscopy;

[0024] Fig. 5 is a polarization rotation vector soliton real-time spectrum feature map tested by a GHz repetition frequency pulse real-time characterization device provided by an embodiment of the present application based on double optical comb spectroscopy;

[0025] Fig. 6 is a scalar soliton real-time spectrum feature map tested by a GHz repetition frequency pulse real-time characterization device provided by an embodiment of the present application based on double optical comb spectroscopy. Embodiment of the present application

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the technical solutions of the present application will be described in detail below with reference to the drawings and specific embodiments. It should be pointed out that the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] Embodiment 1:

[0028] A GHz repetition frequency pulse real-time characterization device based on double optical comb spectroscopy, as shown in Fig. 1, comprises a signal optical comb light source 1, a first polarization controller 2, a polarization beam splitter 3, a local oscillator optical comb light source 4, a first optical coupler 5, a second optical coupler 6, a first photodetector 7, a third optical coupler 8, a second photodetector 9, a high-speed oscilloscope 10 and a data processing module 11.

[0029] The output end of the signal optical comb light source 1 is sequentially connected with the first polarization controller 2 and the polarization beam splitter 3, so as to resolve two orthogonal polarization components of a vector soliton and input them into the second optical coupler 6 and the third optical coupler 8 respectively. The output of the local oscillator optical comb light source 4 is split by the first optical coupler 5 and then recombined with the two orthogonal polarization components in the second optical coupler 6 and the third optical coupler 8 respectively, and then beat interference is carried out in the first photodetector 7 and the second photodetector 9 respectively. The output ends of the first photodetector 7 and the second photodetector 9 are connected with the high-speed oscilloscope 10, and the beat interference results of the first photodetector 7 and the second photodetector 9 are displayed as time domain interference diagrams in the high-speed oscilloscope 10. The high-speed oscilloscope 10 collects the displayed time domain interference diagrams and carries out data processing in the data processing module 11, so as to measure the spectrum characteristics of different soliton type GHz repetition frequency pulses output by the signal optical comb light source 1 in real time.

[0030] Further, the polarization beam splitter 3 has two fiber outputs to separate the two orthogonal polarization components of the vector soliton.

[0031] Further, the local light comb light source 4 has a wider spectral range than the signal light comb light source 1, and maintains linear polarization output.

[0032] Further, the splitting ratios of the first optical coupler 5, the second optical coupler 6 and the third optical coupler 8 are all 1:1.

[0033] Further, the data processing module 11 performs Fourier transform processing on the time domain interferogram to obtain real-time spectral characteristics.

[0034] Further, as shown in FIG. 2, the signal light comb light source 1 includes a piezoelectric actuator 12, a semiconductor saturable absorber mirror 13, a second polarization controller 14, a gain fiber 15, a dielectric film 16, a ferrule 17, a wavelength division multiplexer 18, a pump source 19, an isolator 20, a fourth optical coupler 21, a carrier envelope offset frequency locking module 22 and a repetition frequency locking module 23.

[0035] Among them, the middle part of the gain fiber 15 passes through the second polarization controller 14, and the two ends are respectively connected with the front surface of the semiconductor saturable absorber mirror 13 and the dielectric film 16; the back surface of the semiconductor saturable absorber mirror 13 is pasted on the piezoelectric actuator 12, and the dielectric film 16 is coated on the end face of the ferrule 17; the pump end of the wavelength division multiplexer 18 is connected with the pump source 19, the common end is connected with the tail fiber of the ferrule 17, and the signal end is connected with the isolator 20; the signal light output through the isolator 20 is divided into three beams through the fourth optical coupler 21, the first beam is connected with the carrier envelope offset frequency locking module 22, and is fed back to the pump source 19 to realize carrier envelope offset frequency locking; the second beam is connected with the repetition frequency locking module 23, and is fed back to the piezoelectric actuator 12 to realize repetition frequency locking; the third beam is directly output.

[0036] Further, the devices used in the signal light comb light source 1 are all polarization-independent types, that is, the polarization direction is allowed to change randomly.

[0037] Further, the splitting ratio of the fourth optical coupler 21 is 1:1:1.

[0038] Further, the carrier envelope offset frequency locking module 22 detects the carrier envelope offset frequency of the signal light, and feeds back the jitter error signal to the pump source 19 to adjust the pump power and realize carrier envelope offset frequency locking.

[0039] Further, the repetition frequency locking module 23 detects the repetition frequency of the signal light, and feeds back the jitter error signal to the piezoelectric actuator 12 to change the resonant cavity length and realize repetition frequency locking.

[0040] Figure 1 is a schematic diagram of a GHz repetition rate pulse real-time characterization device based on dual-comb spectroscopy according to an embodiment. Figure 2 is a schematic diagram of a signal comb source according to an embodiment. In the signal comb source 1, the fiber cavity is a Fabry-Perot cavity structure, which mainly consists of a piece of 10 cm long thulium-doped gain fiber 15, a semiconductor saturable absorber mirror 13 and a dielectric mirror 16. The semiconductor saturable absorber mirror 13 has a modulation depth of 12% and a saturation fluence of 65 μJ / cm 2 The dielectric mirror is a multi-layered SiO2 / Ta2O5 thin film stack, which has a transmittance of 90% at the pump wavelength of 1570 nm and a reflectance of 90% in the wavelength range of 1900 nm-2000 nm. The pump source 19 is a 1570 nm continuous wave fiber laser with a maximum power of 500 mW. The pump light is coupled into the cavity through a 1570 / 1950 nm wavelength division multiplexer 18 from the dielectric mirror 16. A fiber isolator 20 is connected to the output end to protect the resonant cavity from back-reflected light. After the signal light output is frequency-locked in two degrees of freedom by the carrier envelope offset frequency locking module 22 and the repetition rate locking module 23, a stable comb signal is formed. By adjusting the second polarization controller 14 in the resonant cavity of the signal comb source 1, the fiber birefringence in the cavity is changed, and thus GHz repetition rate pulses of different soliton types are output.

[0041] The signal comb source 1 is separated into two orthogonal polarization components, i.e., the vertical component and the horizontal component vector solitons, after passing through the first polarization controller 2 and the polarization beam splitter 3 outside the cavity. The intensity of the two orthogonal polarization components can be changed by adjusting the first polarization controller 2. Here, the fundamental repetition rate of the signal comb source 1 is 1.018340 GHz, while the fundamental repetition rate of the local comb source 4 is 1.018498 GHz, with a repetition rate difference of 158 kHz between them, which supports the realization of GHz repetition rate dual-comb spectroscopy. The signal light of the vertical component and the horizontal component are combined with the local comb source 4 in an optical coupler, and then interfere in a photodetector to produce a radio frequency comb composed of a pair of optical comb teeth heterodyne beat frequency, which presents as an asynchronous pulse interference pattern in the time domain.

[0042] Figure 3 is a diagram of the output spectrum of the GHz repetition rate dual-comb in the present embodiment. The center wavelength of the local oscillator comb source 4 is 1970 nm, and the 3 dB spectral bandwidth is about 8.5 nm; the center wavelength of the signal comb source 1 is 1969 nm, and the 3 dB spectral bandwidth is about 3.5 nm. It can be seen that the spectral bandwidth of the local oscillator comb source 4 is wider, and greatly contains the spectrum of the signal comb source 1, so that the GHz repetition rate pulse dynamics measurement can be effectively realized based on the dual-comb spectroscopy measurement method. The frequency bandwidth of the high-speed oscilloscope 10 is 20 GHz, and the sampling rate is set to 10 GSa / s. The real-time radio frequency spectrum is obtained by Fourier transform of a single interferogram, and then the wavelength mapping is transformed back to the optical frequency to obtain the real-time spectral information. The mapping factor is determined by the repetition frequency and the repetition frequency difference. In the present embodiment, the repetition frequency difference of the dual-comb is 158 kHz, and the collection time of a single time-domain interferogram is only 6.3 μs, so that the high refresh rate advantage of the GHz high repetition rate dual-comb spectroscopy measurement technology can be fully utilized.

[0043] In the present embodiment, by carefully adjusting the external first polarization controller 2, the two orthogonal components output by the signal comb source 1 are aligned with the vertical and horizontal axes of the polarization beam splitter 3 and are respectively resolved. After real-time measurement of the dual-comb spectrum, the real-time spectral characteristics output along the two polarization axes of the polarization beam splitter 3 are shown in Figure 4. It can be seen that the spectra of the vertical and horizontal components have different center wavelengths, which are 1968.6 nm and 1970.2 nm, respectively. The difference in the center wavelengths of the orthogonal polarization components is usually used to overcome the group velocity difference caused by the fiber birefringence, which is a typical feature of the group velocity locked vector soliton. Therefore, the two orthogonal polarization components can be captured together and propagate at the same group velocity.

[0044] Embodiment 2:

[0045] This embodiment provides a real-time characterization device for GHz repetition rate pulses based on dual-comb spectroscopy, with the same system structure as Embodiment 1. By adjusting the second polarization controller 14 of the signal comb light source 1, the birefringence of the fiber within the resonant cavity is changed, switching the state of the group velocity-locked vector soliton to the polarization-rotating vector soliton state. The characteristic of the polarization-rotating vector soliton is that the pulse intensity along the two polarization components changes periodically with the round-trip time within the cavity, which is different from the spectral characteristics of the group velocity-locked vector soliton in Embodiment 1. When the external second polarization controller 14 is adjusted to make the energies of the two axes coupled into the polarization beam splitter consistent, the measured real-time spectral characteristics are shown in Figure 5. This indicates that the real-time characterization device for GHz repetition rate pulses based on dual-comb spectroscopy can achieve different state switching of GHz repetition rate pulses by controlling the birefringence within the cavity, and can effectively characterize the spectral information under different states in real time, which is difficult to achieve using traditional averaging measurement methods.

[0046] Example 3:

[0047] This embodiment provides a real-time characterization device for GHz repetition rate pulses based on dual-comb spectroscopy, with the same system structure as Embodiment 1. By changing the fiber birefringence and pump power within the resonant cavity, the vector soliton state of the GHz repetition rate pulse is switched to the scalar soliton state. When the external first polarization controller 2 is adjusted, the spectral intensities of the two orthogonal directions output by the polarization beam splitter always move simultaneously, one increasing and the other decreasing. During this process, the power in one direction can reach its maximum value, while the power in the other direction drops to its minimum. The measured real-time spectral characteristics are shown in Figure 6. It can be seen that the light on the horizontal axis almost disappears, indicating that the soliton has a linear polarization state along the vertical axis. Therefore, the real-time characterization device for GHz repetition rate pulses based on dual-comb spectroscopy can be used to observe the evolution of GHz repetition rate pulses in the scalar soliton state, and has the advantages of high spectral resolution and high refresh rate.

[0048] This invention employs a linearly polarized intrinsic optical comb source to detect the real-time spectral characteristics of a freely polarized signal optical comb source. Therefore, by adjusting the intracavity birefringence of the signal optical comb source, pulse dynamics phenomena of different soliton types can be explored. Furthermore, based on the different operating wavelength parameters of the intracavity fiber, pump source, and fiber optic devices, real-time measurement of GHz repetition frequency pulse dynamics based on dual-comb spectral measurement technology can be achieved.

[0049] This invention addresses the real-time measurement of GHz repetition frequency pulse dynamics. It utilizes dual-comb spectral measurement technology to measure the spectral characteristics of GHz repetition frequency pulses with different soliton types in real time. It has advantages such as high spectral resolution, high refresh rate, and system integrability. It solves the problems of traditional averaging measurement methods in effectively characterizing soliton evolution phenomena and transient changes in GHz repetition frequency pulse dynamics of special band fiber lasers such as 2 μm.

[0050] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A GHz-repetition-rate pulse real-time characterization device based on dual-comb spectroscopy, characterized in that, The application relates to a vector soliton spectrum measurement device, which comprises a signal light comb light source (1), a first polarization controller (2), a polarization beam splitter (3), a local light comb light source (4), a first optical coupler (5), a second optical coupler (6), a first photodetector (7), a third optical coupler (8), a second photodetector (9), a high-speed oscilloscope (10) and a data processing module (11). The output end of the signal light comb light source (1) is sequentially connected with the first polarization controller (2) and the polarization beam splitter (3) to resolve two orthogonal polarization components of the vector soliton and input the two orthogonal polarization components into the second optical coupler (6) and the third optical coupler (8) respectively; the output of the local light comb light source (4) is split by the first optical coupler (5) and then combined with the two orthogonal polarization components in the second optical coupler (6) and the third optical coupler (8) respectively, and then frequency beat interference is carried out in the first photodetector (7) and the second photodetector (9) respectively; the output ends of the first photodetector (7) and the second photodetector (9) are connected with the high-speed oscilloscope (10), and the frequency beat interference results of the first photodetector (7) and the second photodetector (9) are displayed as time-domain interference diagrams in the high-speed oscilloscope (10); the high-speed oscilloscope (10) collects the displayed time-domain interference diagrams and carries out data processing in the data processing module (11) to measure the spectral characteristics of different soliton type GHz repetition frequency pulses output by the signal light comb light source (1) in real time.

2. The GHz-repetition-rate pulsed real-time characterization device based on dual-comb spectroscopy according to claim 1, characterized in that, The polarization beam splitter (3) has two fiber output ends to separate the two orthogonal polarization components of the vector soliton. 3.The GHz repetition rate pulsed real-time characterization device based on dual-comb spectroscopy of claim 1, wherein, The local light comb light source (4) has a wider spectral range than the signal light comb light source (1) and maintains linear polarization output.

4. The GHz-repetition-rate pulsed real-time characterization device based on dual-comb spectroscopy of claim 1, wherein, The splitting ratios of the first optical coupler (5), the second optical coupler (6) and the third optical coupler (8) are all 1:

1.

5. The GHz-repetition-rate pulsed real-time characterization device based on dual-comb spectroscopy of claim 1, wherein, The data processing module (11) carries out Fourier transform processing on the time-domain interference diagrams to obtain real-time spectral characteristics.

6. The GHz-repetition-rate pulsed real-time characterization device based on dual-comb spectroscopy of claim 1, wherein, The signal light comb light source (1) comprises a piezoelectric actuator (12), a semiconductor saturable absorber mirror (13), a second polarization controller (14), a gain fiber (15), a dielectric film (16), a ferrule (17), a wavelength division multiplexer (18), a pump source (19), an isolator (20), a fourth optical coupler (21), a carrier envelope offset frequency locking module (22) and a repetition frequency locking module (23). The middle part of the gain fiber (15) passes through the second polarization controller (14), and the two ends are respectively connected with the semiconductor saturable absorber mirror (13) and the front surface of the dielectric film (16); the back surface of the semiconductor saturable absorber mirror (13) is attached to the piezoelectric actuator (12), and the dielectric film (16) is coated on the end face of the ferrule (17); the pump end of the wavelength division multiplexer (18) is connected with the pump source (19), the common end is connected with the tail fiber of the ferrule (17), and the signal end is connected with the isolator (20); the signal light output through the isolator (20) is input into the fourth optical coupler (21) to divide into three beams, the first beam is input into the carrier envelope offset frequency locking module (22) and fed back to the pump source (19) to realize carrier envelope offset frequency locking; the second beam is input into the repetition frequency locking module (23) and fed back to the piezoelectric actuator (12) to realize repetition frequency locking; and the third beam is directly output.

7. The GHz-repetition-rate pulsed real-time characterization device based on dual-comb spectroscopy according to claim 6, characterized in that, The signal light comb light source (1) adopts polarization-independent devices, that is, the polarization direction is allowed to change randomly.

8. The GHz-repetition-rate pulsed real-time characterization device based on dual-comb spectroscopy according to claim 6, characterized in that, The splitting ratio of the fourth optical coupler (21) is 1:1:

1.

9. The GHz-repetition-rate pulsed real-time characterization device based on dual-comb spectroscopy of claim 6, wherein, The carrier envelope offset frequency locking module (22) detects the carrier envelope offset frequency of the signal light, and feeds back the jitter error signal to the pump source (19) to adjust the pump power and realize carrier envelope offset frequency locking.

10. The GHz-repetition-rate pulsed real-time characterization device based on dual-comb spectroscopy of claim 6, wherein, The repetition frequency locking module (23) detects the repetition frequency of the signal light, and feeds back the jitter error signal to the piezoelectric actuator (12) to change the resonant cavity length and realize repetition frequency locking.

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