All-fiber real-time ranging system based on free-running single-cavity dual-comb

Abstract

The present application relates to the field of precision optical measurement, in particular to a free-running single-cavity dual-comb based all-fiber real-time distance measurement system.The free-running single-cavity dual-comb based all-fiber real-time distance measurement system comprises a free-running single-cavity dual-comb light source and an all-fiber real-time distance measurement system.The present application adopts a free-running single-cavity dual-comb, which is an integrated structure, instead of two independent optical combs in the original scheme to carry out dual-comb absolute distance measurement, thus saving the structure of the original scheme, simplifying the structure of the locking mechanism or the detection module, and being more conducive to the high integration and miniaturization of the system, and obviously reducing the cost of the dual-comb light source.Meanwhile, the free-running single-cavity dual-comb adopted by the present application generates pulsed light in the same optical resonant cavity, and the two pulsed lights have homology and strong anti-interference, thereby better suppressing the common-mode noise in the cavity, ensuring the coherence of the light beam, and improving the quality and signal-to-noise ratio of the beat frequency signal.

Description

Technical Field

[0001] This invention relates to the field of precision optical measurement technology, and more specifically, to an all-fiber real-time ranging system based on a free-running single-cavity dual optical comb. Background Technology

[0002] In recent years, with the significant improvement in the response speed, measurement accuracy, and resolution of optical response devices such as photodetectors, and the gradual perfection of precision optical metrology technology, large-range, high-precision, and high-speed precision optical ranging technology is gradually becoming a reality. An optical frequency comb (hereinafter referred to as an optical frequency comb) is, in the time domain, a series of equally spaced ultrashort pulse sequences (pulse widths on the order of picoseconds or femtoseconds), and in the frequency domain, it consists of equally spaced longitudinal modes forming comb teeth, with the interval between adjacent comb teeth equal to the repetition frequency of the pulse sequence. Since the advent of optical frequency combs based on femtosecond laser technology in the late 1990s, optical frequency combs have become an important light source in the field of optical precision metrology due to their high peak energy, high frequency stability, and high precision.

[0003] Existing absolute distance measurement methods based on optical frequency combs typically combine two optical frequency combs with a repetition frequency difference on the order of Hz-kHz to form a dual optical frequency comb light source. Combined with a spatial optical ranging module based on polarization optics, coherent and incoherent distance information can be detected quickly and without scanning.

[0004] However, existing technical solutions require complex repetition frequency locking mechanisms for the dual-comb light source, or the use of additional frequency counting devices and repetition frequency detection modules for real-time repetition frequency calibration; they also require complex optical design and precise assembly and debugging techniques to construct a complete spatial optical ranging module. This results in high complexity, large size, and high cost for dual-comb ranging systems, severely limiting their practical value and prospects for widespread application in actual industrial and engineering testing.

[0005] Therefore, it is necessary to explore dual-comb ranging systems that are simpler in structure, lower in cost, and easier to implement. Summary of the Invention

[0006] The purpose of this invention is to provide an all-fiber real-time ranging system based on a free-running single-cavity dual optical comb, in order to solve the problems mentioned in the background art, such as the high complexity, large size, and high cost of the existing dual optical comb ranging system, which seriously limits the practical value and promotion prospects of dual optical comb ranging equipment in actual industrial and engineering testing.

[0007] To achieve the above objectives, the present invention aims to provide an all-fiber real-time ranging system based on a free-running single-cavity dual-optical-comb, comprising a free-running single-cavity dual-optical-comb light source and an all-fiber real-time ranging system. The free-running single-cavity dual-optical-comb light source is used to perform the output process of the free-running single-cavity dual-optical-comb, and the all-fiber real-time ranging system is used to perform the measurement process of the all-fiber ranging module. The free-running single-cavity dual-comb light source consists of a pumped LD light source, a wavelength division multiplexer, a saturable absorber, a polarization controller, a 2×2 polarization-maintaining fiber beam splitter, and a gain fiber 1. The all-fiber real-time ranging system consists of a first 1×2 polarization-maintaining fiber beam splitter, a second 1×2 polarization-maintaining fiber beam splitter, a polarization-maintaining fiber circulator, a fiber collimator, a total reflection mirror, a first 2×1 polarization-maintaining fiber coupler, a second 2×1 polarization-maintaining fiber coupler, a detector, and a measurement and control unit.

[0008] As a further improvement to this technical solution, the free-running single-cavity dual-comb output process includes the following steps: the light output from the pump LD light source is coupled into the gain fiber through a wavelength division multiplexer. After the gain fiber absorbs the pump light output from the pump LD light source, it generates a signal light with a wavelength of 1550nm. The signal light rotates clockwise and counterclockwise in the free-running single-cavity dual-comb light source.

[0009] As a further improvement to this technical solution, the 2×2 polarization-maintaining fiber beam splitter is used to simultaneously output two pulsed lasers with repetition frequencies of f1 and f2, and there is a difference Δf between the two pulsed lasers.

[0010] As a further improvement to this technical solution, the polarization controller is used to adjust the polarization state inside the free-running single-cavity dual-comb light source, and the saturated absorber is used for mode locking inside the free-running single-cavity dual-comb light source.

[0011] As a further improvement to this technical solution, the pulsed laser with a repetition frequency of f1 output by the free-running single-cavity dual-comb light source is used as the measurement signal light of the all-fiber real-time ranging system, and the pulsed laser with a repetition frequency of f2 output by the free-running single-cavity dual-comb light source is used as the local oscillator signal light.

[0012] As a further improvement to this technical solution, the measurement process of the all-fiber ranging module includes the following steps: the measurement signal light and the local oscillator signal light are split by the first 1×2 polarization-maintaining fiber beam splitter and the second 1×2 polarization-maintaining fiber beam splitter, respectively.

[0013] As a further improvement to this technical solution, the measurement process of the all-fiber ranging module also includes the following steps: one of the beams of the measurement signal light after being split enters the polarization-maintaining fiber circulator, and is converted into spatial light by the fiber collimator. After traveling a certain distance, the spatial light is reflected by the total reflection mirror, coupled into the polarization-maintaining fiber circulator by the fiber collimator, and then enters the first 2×1 polarization-maintaining fiber coupler after being split by the polarization-maintaining fiber circulator and beats the signal. Finally, the ranging signal is detected by the detector.

[0014] As a further improvement to this technical solution, the measurement process of the all-fiber ranging module also includes the following steps: after the other beam of the measurement signal light and the other beam of the local oscillator signal light enter the second 2×1 polarization-maintaining fiber coupler to beat, the reference signal is finally detected by the detector.

[0015] As a further improvement to this technical solution, the measurement and control unit is used to acquire, process, calculate and digitally display signals, realize the acquisition and processing of two signals, calculate the measured distance in real time through the ranging algorithm, and display and store the results in real time.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. This invention adopts a free-running single-cavity dual optical comb. This scheme is an integrated structure that replaces the two independent optical combs in the original scheme to carry out dual optical comb absolute ranging research. It eliminates the need for a mode-locking mechanism or a detection module, simplifying the structure and making it more conducive to the high integration and miniaturization of the system. It also significantly reduces the cost of the dual optical comb light source.

[0018] 2. The free-running single-cavity dual optical comb used in this invention generates pulsed light in the same optical resonant cavity. The two pulsed lights have homogeneity and strong anti-interference ability, thereby better suppressing intracavity common-mode noise, ensuring the coherence of the beam, and improving the quality and signal-to-noise ratio of the beat frequency signal.

[0019] 3. The present invention adopts an all-fiber ranging system solution, which can effectively reduce the interference of external stray light signals and does not require complex assembly and debugging processes. It simplifies the system assembly and debugging process, effectively simplifies the structure of the entire system, enhances the stability and anti-interference capability of the ranging system, and makes system integration easier to achieve. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the all-fiber real-time ranging system based on a free-running single-cavity dual optical comb of the present invention.

[0021] Figure 2 This is a schematic diagram illustrating the principle of the dual-frequency comb ranging method of the present invention.

[0022] Figure 3The figure shows the measurement results of the dual-frequency comb ranging system of the present invention.

[0023] In the diagram: 1. Free-running single-cavity dual-comb light source; 11. Pumped LD light source; 12. Wavelength division multiplexer; 13. Saturable absorber; 14. Polarization controller; 15. 2×2 polarization-maintaining fiber beam splitter; 16. Gain fiber; 2. All-fiber real-time ranging system; 211. First 1×2 polarization-maintaining fiber beam splitter; 212. Second 1×2 polarization-maintaining fiber beam splitter; 22. Polarization-maintaining fiber circulator; 23. Fiber collimator; 24. Total reflection mirror; 251. First 2×1 polarization-maintaining fiber coupler; 252. Second 2×1 polarization-maintaining fiber coupler; 26. Detector; 27. Measurement and control unit. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In one specific embodiment, such as Figure 1 As shown, the present invention provides an all-fiber real-time ranging system based on a free-running single-cavity dual-comb light source 1 and an all-fiber real-time ranging system 2.

[0026] Free-running single-cavity dual-comb output process: Inside the free-running single-cavity dual-comb light source 1, the light output from the pump LD light source 11 is coupled to the gain fiber 16 through the wavelength division multiplexer 12. After the gain fiber 16 absorbs the pump light, it generates a signal light with a wavelength of 1550nm. The signal light rotates clockwise and counterclockwise in the cavity.

[0027] The 2×2 polarization-maintaining fiber beam splitter 15 simultaneously outputs two pulsed lasers with repetition frequencies of f1 and f2, with a small difference Δf between the two repetition frequencies.

[0028] The polarization controller 14 is used to adjust the polarization state inside the cavity, and the saturable absorber 13 is used for mode locking inside the cavity. The two work together to ensure the long-term stable operation of the resonant cavity.

[0029] Measurement process of the all-fiber ranging module: In the all-fiber real-time ranging system 2, the free-running single-cavity dual-comb light source 1 outputs a pulsed laser with a repetition frequency of f1 as the measurement signal light of the all-fiber real-time ranging system 2, and a pulsed laser with a repetition frequency of f2 as the local oscillator signal light. The two signal lights are split by the first 1×2 polarization-maintaining fiber beam splitter 211 and the second 1×2 polarization-maintaining fiber beam splitter 212, respectively. One beam of the measurement signal light passes through the polarization-maintaining fiber circulator 22 and is converted into spatial light by the fiber collimator 23. After traveling a certain distance, the spatial light is reflected by the total reflection mirror 24, coupled into the polarization-maintaining fiber circulator 22 by the fiber collimator 23, and then enters the first 2×1 polarization-maintaining fiber coupler 251 after passing through the polarization-maintaining fiber circulator 22 and one of the local oscillator signal lights. Finally, the ranging signal is detected by the detector 26.

[0030] Simultaneously, the other beam of the measurement signal light and the other beam of the local oscillator signal light enter the second 2×1 polarization-maintaining fiber coupler 252 for beat frequency, and finally the reference signal is detected by the detector 26.

[0031] In addition, the main function of the measurement and control unit 27 is to acquire, process, calculate and digitally display signals, including filtering, noise reduction, sampling and high-speed digital signal processing, to acquire and process two signals, and to calculate the measured distance in real time through the ranging algorithm, while displaying and storing the results in real time.

[0032] At the same time, such as Figure 2 The diagram shown is a schematic representation of the principle of the dual-frequency comb ranging method of the present invention. Figure 3 The figure shown is a measurement result diagram of the dual-frequency comb ranging system of the present invention.

[0033] In summary, based on the problems existing in the prior art, this invention provides a real-time all-fiber ranging system based on a free-running single-cavity dual-optical-comb, which has a simpler structure, is more convenient to operate, and has higher measurement accuracy, and achieves the following technical effects: This invention employs a free-running single-cavity dual optical comb, which is an integrated structure that replaces the two independent optical combs in the original scheme for conducting dual optical comb absolute ranging research. It eliminates the need for a mode-locking mechanism or a detection module, simplifying the structure and making the system more highly integrated and miniaturized. It also significantly reduces the cost of the dual optical comb light source.

[0034] The invention employs a free-running single-cavity dual optical comb, where pulsed light is generated in the same optical resonant cavity. The two pulsed light beams have homogeneity and strong anti-interference ability, thereby better suppressing intracavity common-mode noise, ensuring beam coherence, and improving the quality and signal-to-noise ratio of the beat frequency signal.

[0035] This invention adopts an all-fiber ranging system solution, which can effectively reduce interference from external stray light signals and does not require complex assembly and debugging processes. It simplifies the system assembly and debugging process, effectively simplifies the structure of the entire system, enhances the stability and anti-interference capability of the ranging system, and makes system integration easier.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An all-fiber real-time range-finding system based on a free-running single-cavity dual-comb, characterized in that, It includes a free-running single-cavity dual-comb light source (1) and an all-fiber real-time ranging system (2). The free-running single-cavity dual-comb light source (1) is used to perform the free-running single-cavity dual-comb output process, and the all-fiber real-time ranging system (2) is used to perform the all-fiber ranging module measurement process. The free-running single-cavity dual-comb light source (1) consists of a pumped LD light source (11), a wavelength division multiplexer (12), a saturable absorber (13), a polarization controller (14), a 2×2 polarization-maintaining fiber beam splitter (15), and a gain fiber 1 (16). The all-fiber real-time ranging system (2) consists of a first 1×2 polarization-maintaining fiber beam splitter (211), a second 1×2 polarization-maintaining fiber beam splitter (212), a polarization-maintaining fiber circulator (22), a fiber collimator (23), a total reflection mirror (24), a first 2×1 polarization-maintaining fiber coupler (251), a second 2×1 polarization-maintaining fiber coupler (252), a detector (26), and a measurement and control unit (27).

2. The free-running single-cavity dual-comb based all-fiber real-time ranging system according to claim 1, wherein, The free-running single-cavity dual-comb output process includes the following steps: the light output from the pump LD light source (11) is coupled into the gain fiber (16) through the wavelength division multiplexer (12). After the gain fiber (16) absorbs the pump light output from the pump LD light source (11), it generates a signal light with a wavelength of 1550nm. The signal light runs clockwise and counterclockwise in the free-running single-cavity dual-comb light source (1).

3. The free-running single-cavity dual-comb based all-fiber real-time ranging system according to claim 2, wherein, The 2×2 polarization-maintaining fiber beam splitter (15) is used to simultaneously output two pulsed lasers with repetition frequencies of f1 and f2, and there is a difference Δf between the two pulsed lasers.

4. The free-running single-cavity dual-comb based all-fiber real-time ranging system according to claim 2, wherein, The polarization controller (14) is used to adjust the polarization state inside the free-running single-cavity dual-comb light source (1), and the saturated absorber (13) is used for mode locking inside the free-running single-cavity dual-comb light source (1).

5. The free-running single-cavity dual-comb based all-fiber real-time ranging system according to claim 3, wherein, The free-running single-cavity dual-comb light source (1) outputs a pulsed laser with a repetition frequency of f1 as the measurement signal light of the all-fiber real-time ranging system (2), and the free-running single-cavity dual-comb light source (1) outputs a pulsed laser with a repetition frequency of f2 as the local oscillator signal light.

6. The free-running single-cavity dual-comb based all-fiber real-time ranging system according to claim 5, wherein, The measurement process of the all-fiber ranging module includes the following steps: the measurement signal light and the local oscillator signal light are split by the first 1×2 polarization-maintaining fiber beam splitter (211) and the second 1×2 polarization-maintaining fiber beam splitter (212), respectively.

7. The free-running single-cavity dual-comb based all-fiber real-time ranging system according to claim 6, wherein, The measurement process of the all-fiber ranging module also includes the following steps: one of the beams of the measurement signal light after being split enters the polarization-maintaining fiber circulator (22), and is converted into spatial light by the fiber collimator (23). After traveling a distance, the spatial light is reflected by the total reflection mirror (24), coupled into the polarization-maintaining fiber circulator (22) through the fiber collimator (23), and then enters the first 2×1 polarization-maintaining fiber coupler (251) after being split by the polarization-maintaining fiber circulator (22). Finally, the ranging signal is detected by the detector (26).

8. The free-running single-cavity dual-comb based all-fiber real-time ranging system according to claim 7, wherein, The all-fiber distance measuring module measuring process further comprises the following steps: after another beam of signal light and another beam of local signal light enter a second 2×1 polarization maintaining fiber coupler (252) and beat, the reference signal is finally detected by the detector (26).

9. The free-running single-cavity dual-comb based all-fiber real-time ranging system according to claim 1, wherein, The measurement and control unit (27) is used for signal acquisition, processing, calculation and digital display, realizes acquisition and processing of two-way signals, and through distance measurement algorithm, real-time calculation of measurement distance is realized, and the results are displayed and stored in real time.

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