Mode-locked measuring device for space-time mode-locked laser

Abstract

The utility model relates to a mode-locked measuring device for space-time mode-locked laser. The mode-locked measuring device comprises a space-time mode-locked fiber laser, a space sampling device and a detection device which are connected in sequence, the space sampling device comprises a first optical coupler, a first collimator, a beam splitter, a first diaphragm, a second collimator, a second diaphragm and a third collimator which are connected in sequence; a first space channel is formed among the beam splitter, the first diaphragm and the second collimator; a second space channel is formed among the beam splitter, the second diaphragm and the third collimator; the first diaphragm is movably arranged between the beam splitter and the second collimator; the second diaphragm is movably arranged between the beam splitter and the third collimator; the second collimator and the third collimator are respectively connected with the detection device; the first optical coupler is connected with the output end of the space-time mode-locked fiber laser; the technical problems that a mode-locked measuring device of a traditional space-time mode-locked laser is too complex in structure and high in cost are solved.

Description

Technical Field

[0001] This utility model relates to the field of optical measurement technology, and in particular to a mode-locking measurement device for spatiotemporal mode-locking lasers. Background Technology

[0002] Spacetime mode-locked (STML) fiber lasers, capable of simultaneous mode-locking in both time and space to generate ultrashort pulse lasers with complex spatiotemporal structures, high precision, high energy density, and high stability, are widely used in ultrafast spectroscopy, nonlinear optics, spatiotemporal dynamics, quantum optics, quantum information science, and fiber optic communication. They have become an ideal choice for many cutting-edge technologies and applications. Research in these fields primarily uses spatial optical path fiber lasers as the laser source for STML lasers, employing methods such as 3D delayed scanning off-axis digital holography or spatiotemporal spectral compression ultrafast photography to verify the synchronization of spatiotemporal mode-locking, especially transverse mode (spatial mode-locking), in pulsed lasers. This research explores the impact of different conditions or devices on the spatiotemporal mode-locking of pulsed lasers.

[0003] However, the measurement methods such as 3D delayed scanning off-axis digital holography or spatiotemporal spectral compression ultrafast photography often involve the coordination of a variety of high-precision optical components, and their structures are often quite complex and the cost of the components is relatively high. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a mode-locking measurement device for spatiotemporal mode-locking lasers, which solves the technical problems of the overly complex structure and high cost of traditional mode-locking measurement devices for spatiotemporal mode-locking lasers.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the main technical solutions adopted by this utility model include:

[0008] This utility model provides a mode-locking measurement device for a spatiotemporally mode-locked laser, comprising a spatiotemporally mode-locked fiber laser, a spatial sampling device, and a detection device connected in sequence.

[0009] The spatial sampling device includes a first optical coupler, a first collimator, a beam splitter, a first aperture, a second collimator, a second aperture, and a third collimator connected in sequence.

[0010] A first spatial channel is formed between the beam splitter, the first aperture, and the second collimator; a second spatial channel is formed between the beam splitter, the second aperture, and the third collimator.

[0011] The first aperture is movably positioned between the beam splitter and the second collimator; the second aperture is movably positioned between the beam splitter and the third collimator.

[0012] The second and third collimators are connected to the detection device, respectively; the first optical coupler is connected to the output end of the spatiotemporal mode-locked fiber laser.

[0013] Preferably, the first and second apertures have the same aperture; the apertures of the first and second apertures are smaller than the radius of the beam split by the beam splitter.

[0014] Preferably, the first aperture and the second aperture are respectively disposed on the aperture base; the first aperture and the second aperture are variable apertures.

[0015] Preferably, the detection device includes a pulse information detection device and a spectral information detection device.

[0016] Preferably, the optical fiber used in the spatial sampling device is a passive multimode optical fiber; the beam splitter has a splitting ratio of 50:50.

[0017] Preferably, one end of the first optical coupler is also connected to a control detection device; the splitting ratio of the first optical coupler is 90:10.

[0018] Preferably, the spatiotemporal mode-locked fiber laser includes a first semiconductor saturable absorber mirror, a second optical coupler, a first polarization controller, a gain fiber, a beam combiner, a second polarization controller, and a second semiconductor saturable absorber mirror connected in sequence.

[0019] A pump source is also connected to one end of the combiner near the second semiconductor saturable absorber mirror;

[0020] The splitting ratio of the second optical coupler is adjustable, and the output of the second optical coupler is connected to the first optical coupler.

[0021] Preferably, the spatiotemporal mode-locked fiber laser is an all-fiber laser;

[0022] The first semiconductor saturable absorber mirror, the second optical coupler, and the first polarization controller constitute the first optical fiber segment;

[0023] The second fiber segment is composed of a beam combiner, a second polarization controller, and a second semiconductor saturable absorber mirror.

[0024] The gain fiber is fused to the first fiber segment.

[0025] Preferably, the core diameter of the optical fiber in the first optical fiber segment is larger than the core diameter of the gain optical fiber; the core diameter of the optical fiber in the second optical fiber segment is the same as the core diameter of the gain optical fiber; and the first semiconductor saturable absorber mirror and the second semiconductor saturable absorber mirror are of the same type.

[0026] Preferably, the optical fiber in the first optical fiber segment is a graded-index multimode optical fiber; the optical fiber in the second optical fiber segment is a passive multimode optical fiber; and the gain optical fiber is a ytterbium-doped optical fiber.

[0027] (III) Beneficial Effects

[0028] This invention discloses a mode-locking measurement device for a spatiotemporally mode-locked laser. By incorporating two movable apertures, the device can simultaneously sample different spatial positions of the laser output from a spatiotemporally mode-locked fiber laser by changing the relative positions of the apertures. Accurate spatiotemporal mode-locking information is obtained by analyzing and comparing the pulse and spectral information of different sampled signals using a detection device. Compared to existing technologies, this device is simpler, more flexible, has a wider adjustable range, and is more convenient to use. Furthermore, because the overall structure of this spatial sampling device is relatively simple and does not involve many high-precision, high-value components, its components are easier to obtain and have lower costs compared to existing technologies. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the mode-locking measurement device for spatiotemporal mode-locking laser according to Embodiment 1 of this utility model;

[0030] Figure 2 This is a schematic diagram of the overall structure of the mode-locking measurement device for spatiotemporal mode-locking laser according to Embodiment 2 of this utility model;

[0031] [Explanation of Labels in the Attached Image]

[0032] 1: First optical coupler; 2: First collimator; 3: Beam splitter; 4: First aperture; 5: Second collimator; 6: Second aperture; 7: Third collimator; 8: Comparison detection device; 9: First semiconductor saturable absorber mirror; 10: Second optical coupler; 11: First polarization controller; 12: Gain fiber; 13: Beam combiner; 14: Second polarization controller; 15: Second semiconductor saturable absorber mirror; 16: Pump source. Detailed Implementation

[0033] To better explain and facilitate understanding of this utility model, the present utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] Reference Figure 1 This embodiment provides a mode-locking measurement device for a spatiotemporal mode-locked laser, comprising a spatiotemporal mode-locked fiber laser, a spatial sampling device, and a detection device connected in sequence;

[0036] The spatial sampling device includes a first optical coupler 1, a first collimator 2, a beam splitter 3, a first aperture 4, a second collimator 5, a second aperture 6, and a third collimator 7 connected in sequence.

[0037] A first spatial channel is formed between the beam splitter 3, the first aperture 4, and the second collimator 5; a second spatial channel is formed between the beam splitter 3, the second aperture 6, and the third collimator 7.

[0038] The first aperture 4 is movably disposed between the beam splitter 3 and the second collimator 5; the second aperture 6 is movably disposed between the beam splitter 3 and the third collimator 7.

[0039] The second collimator 5 and the third collimator 7 are respectively connected to the detection device; the first optical coupler 1 is connected to the output end of the spatiotemporal mode-locked fiber laser.

[0040] The three-dimensional spatial position of the first aperture 4 relative to the first spatial channel is not the same as the three-dimensional spatial position of the second aperture 6 relative to the second spatial channel.

[0041] Furthermore, the first aperture 4 and the second aperture 6 have the same aperture; the apertures of the first aperture 4 and the second aperture 6 are smaller than the radius of the beam split by the beam splitter 3.

[0042] Furthermore, the first aperture 4 and the second aperture 6 are respectively disposed on the aperture base; the first aperture 4 and the second aperture 6 are variable apertures.

[0043] Preferably, the diameters of the first aperture 4 and the second aperture 6 are both set to 0.5 mm or 1 mm.

[0044] Reference Figure 1 The spatiotemporal mode-locked fiber laser includes a first semiconductor saturable absorber mirror 9, a second optical coupler 10, a first polarization controller 11, a gain fiber 12, a beam combiner 13, a second polarization controller 14, and a second semiconductor saturable absorber mirror 15 connected in sequence; the beam combiner 13 is also connected to a pump source 16; the output end of the second optical coupler 10 is connected to the first optical coupler 1, and both the first optical coupler 1 and the second optical coupler 10 are optical couplers.

[0045] The spacetime mode-locked fiber laser can also be of other types or structures, and can be replaced according to the specific measurement purpose of the test.

[0046] A spacetime mode-locked fiber laser transmits light to a spatial sampling device. By adjusting the three-dimensional platform of the aperture base, the sampling points of the first aperture 4 and the second aperture 6 are changed, sampling is performed at different spatial positions of the output spacetime mode-locked pulsed laser, thereby obtaining different sampling signals. These sampling signals are transmitted to various detection devices. The output characteristics of the spacetime mode-locked pulsed laser are further characterized by various measurement devices, and the required data are obtained by analyzing these output characteristics.

[0047] Furthermore, the second optical coupler 10 is an adjustable coupler, and the splitting ratio of the second optical coupler 10 is adjustable.

[0048] Preferably, the second optical coupler 10 transmits 50% of the light to the first semiconductor saturable absorber mirror 9 for further reflection, and the other 50% of the light is transmitted to the first optical coupler 1; or the second optical coupler 1 transmits 90% of the light to the first optical coupler 10, and the other 10% of the light is transmitted to the first semiconductor saturable absorber mirror 9 for further reflection.

[0049] Furthermore, the beam splitter 3 has a splitting ratio of 50:50, which enables it to form two identical spatial optical paths.

[0050] Furthermore, the detection device includes a pulse information detection device and a spectral information detection device, wherein the pulse information detection device includes an oscilloscope, a photodetector, and an autocorrelation instrument; the spectral information detection device includes a spectrometer, an RF analyzer, and a charge-coupled device camera.

[0051] Among them, photodetectors are used to convert photoelectric signals, oscilloscopes are mainly used to measure pulse sequences, spectrometers are mainly used to measure spectra, radio frequency spectrum analyzers are mainly used to measure pulse signal-to-noise ratio, autocorrelators are mainly used to measure pulse width, and charge-coupled device cameras are mainly used to measure the spot characteristics of output pulses; the light beams collected by the space sampling device are transmitted to these devices through optical fibers.

[0052] Furthermore, the optical fiber used in the space sampling device is a passive multimode optical fiber, and the core diameter of the passive multimode optical fiber used in the space sampling device is the same as that of the optical fiber used in the first optical fiber segment; specifically, the first optical coupler 1 and the first collimator 2 are connected by a passive multimode optical fiber.

[0053] Furthermore, the second collimator 5 is connected to the detection device via the first output optical fiber; the third collimator 7 is connected to the detection device via the second output optical fiber; the second collimator 5 and the third collimator 7 are lens collimators.

[0054] Preferably, the second collimator 5 is provided with a first focusing lens, and the third collimator 7 is provided with a second focusing lens, so as to ensure the connection effect between the output light of the second collimator 5 and the third collimator 7 and the corresponding optical fiber.

[0055] The second collimator 5 and the third collimator 7 can be connected to the spectrometer, autocorrelator, and charge-coupled device camera via the first and second output optical fibers. When the second collimator 5 and the third collimator 7 are connected to the oscilloscope and the radio spectrum analyzer, the first and second output optical fibers need to be connected to the photodetector first (the photodetector converts the optical signal into an electrical signal), and then the photodetector is connected to the oscilloscope and the radio spectrum analyzer.

[0056] It should be noted that since time-mode-locking detection does not require special sampling, the information collected by the spatial sampling device can simultaneously include both time-mode-locking and spatial-mode-locking information, which can meet the needs of the equipment in the detection device to analyze the time-mode-locking and spatial-mode-locking of the time-space-mode-locked pulse laser.

[0057] Reference Figure 1 The spatiotemporal mode-locked fiber laser is an all-fiber laser, and the first semiconductor saturable absorber mirror 9, the second optical coupler 10 and the first polarization controller 11 form the first fiber segment;

[0058] The beam combiner 13, the second polarization controller 14, and the second semiconductor saturable absorber mirror 15 constitute the second optical fiber segment.

[0059] Furthermore, the gain fiber 12 is fused to the first fiber segment; the core diameter of the fiber in the first fiber segment is larger than the core diameter of the gain fiber 12; the core diameter of the fiber in the second fiber segment is the same as the core diameter of the gain fiber 12; the first semiconductor saturable absorber mirror 9 and the second semiconductor saturable absorber mirror 15 are of the same type.

[0060] In the spatiotemporal mode-locked fiber laser of this embodiment, the specific models of the first semiconductor saturable absorber 9 and the second semiconductor saturable absorber 15 can be replaced according to actual usage requirements, but it is necessary to ensure that the key parameters such as the absorption rate, modulation depth and relaxation time of the first semiconductor saturable absorber 9 and the second semiconductor saturable absorber 15 are the same to ensure modulation stability.

[0061] Preferably, in this embodiment, the semiconductor saturable absorber mirror has an absorption rate of 21%, a modulation depth of 0.14, and a relaxation time of 3 ps, which can respond to high-speed laser pulses and ensure mode-locking stability.

[0062] The pump source 16 can also be replaced according to actual usage requirements. In this embodiment, preferably, the pump source 16 is a 980nm multimode laser diode.

[0063] Furthermore, the optical fiber in the first optical fiber segment is a graded-index multimode optical fiber; the optical fiber in the second optical fiber segment is a passive multimode optical fiber; and the gain fiber 12 is a ytterbium-doped optical fiber.

[0064] Preferably, in the spatiotemporal mode-locked fiber laser, the core diameter of the graded-index multimode fiber is 62.5 / 125μm, and the total length of the graded-index multimode fiber is set to 3.7m; the core diameter of the passive multimode fiber is 20 / 125μm, and the length of the passive multimode fiber is set to 2m; the length of the ytterbium-doped fiber is set to 0.83m.

[0065] Preferably, in the spatiotemporal mode-locked fiber laser, the numerical aperture of the graded-index multimode fiber is 0.275; the numerical aperture of the passive multimode fiber is 0.08; the passive multimode fiber is mechanically connected to the gain fiber 12; the core diameter of the ytterbium-doped fiber is 20 / 125 μm, and the numerical aperture of the ytterbium-doped fiber is 0.08.

[0066] In this embodiment, the spacetime mode-locked laser (hereinafter referred to as the laser under test) generated by the spacetime mode-locked fiber laser passes through the first optical coupler 1 and the first collimator 2 to reach the beam splitter 3. After passing through the beam splitter, the laser under test becomes two identical laser beams (beam 1 and beam 2). Beam 1 and beam 2 enter the first spatial channel and the second spatial channel, respectively. Beam 1 is received by the second collimator 5 after passing through the first aperture 4, and beam 2 is received by the third collimator 7 after passing through the second aperture 6. The beam 3 (beam 3) passing through the first aperture 4 and the beam 4 (beam 4) passing through the second aperture 6 have different transverse mode components (because the first aperture 4 and the second aperture 6 have different relative spatial positions, when sampling beam 1 and beam 2 respectively, it can be equivalent to sampling light at different positions on the cross section of the beam under test, that is, sampling different spatial positions of the laser under test; different transverse modes have different spatial distributions, and the transverse mode components passing through the apertures are also different due to the different spatial positions of the apertures). Beam 3 and beam 4 are input into the detection device for analysis through the second collimator 5 and the third collimator 7.

[0067] This embodiment provides a mode-locking measurement device for a spatiotemporally mode-locked laser. During measurement, it can sample different spatial positions of the laser output from a spatiotemporally mode-locked fiber laser by adjusting the three-dimensional position of the aperture. By analyzing and comparing the pulse and spectral information of different sampled signals, it obtains relatively accurate spatiotemporally mode-locking information. Compared to existing technologies, its structure is more flexible, and the operation is simpler and more convenient for users during sampling measurements. Furthermore, because the overall structure of the spatial sampling device in this embodiment is relatively simple and does not involve many high-value components, its components are easier to obtain and have lower costs compared to existing technologies.

[0068] In this embodiment, when light couples from the small-core fiber (gain fiber 12) into the large-core fiber (graded-index multimode fiber), higher-order modes are excited at the mismatched splice point formed by the fusion of the small-core and large-core fibers. Energy is redistributed. When the modes in the graded-index multimode fiber are reflected by the first semiconductor saturable absorber mirror 9, the stronger modes are retained, while the weaker modes are absorbed. The stronger modes are reflected back into the graded-index multimode fiber by the first semiconductor saturable absorber mirror 9 to continue transmission. When light enters the gain fiber 12 from the graded-index multimode fiber, a spatial filtering effect occurs at the mismatched splice point, filtering out some modes propagating in the graded-index multimode fiber. The light then continues to propagate into the passive multimode fiber matched with the gain fiber 12, and after saturable absorption by the second semiconductor saturable absorber mirror 15, it is reflected back into the passive multimode fiber to continue transmission. The light oscillates back and forth continuously within the resonant cavity, ultimately generating a stable spatiotemporal mode-locked pulse.

[0069] Among them, the semiconductor saturable absorber is a semiconductor saturable absorber, which consists of a Bragg mirror and a single quantum trap absorption layer; the first semiconductor saturable absorber 9 and the second semiconductor saturable absorber 15 can be connected by optical fiber to form a Fabry-Perot resonant cavity (hereinafter referred to as the resonant cavity), in which light can circulate and complete mode locking.

[0070] Since this embodiment uses two identical first semiconductor saturable absorber mirrors 9 and 15 and an all-fiber structure, compared with the prior art, it can reduce the modulation instability of the spatiotemporally mode-locked fiber laser and the optical loss during the modulation process, which is beneficial to the realization of spatiotemporal mode-locking and also helps to enhance mode-locking stability.

[0071] Furthermore, this embodiment employs two types of optical fibers with different core diameters (62.5 / 125μm graded-index multimode fiber and 20 / 125μm gain fiber 12 and their matching passive multimode fiber). When the fibers with different core diameters are spliced, they will form mismatched splice points. Compared with the prior art, this allows the light in the first fiber segment and the second fiber segment to be in different mode stages. The first semiconductor saturable absorber mirror 9 and the second semiconductor saturable absorber mirror 15 can be used to mode-lock the light in different modes respectively, improving the spatiotemporal mode-locking effect. It also allows the light to continuously undergo mode conversion and filtering as it oscillates back and forth in the resonant cavity, improving the stability and mode-locking effect of spatiotemporal mode-locking.

[0072] In addition, this embodiment also provides a first polarization controller 11 and a second polarization controller 14 on the optical fibers of the first optical fiber segment and the second optical fiber segment, respectively. Compared with the prior art, it can adjust the light in different modes in the first optical fiber segment and the second optical fiber segment, which greatly increases the adjustment effect on the polarization state of the control light, making the adjustment more flexible and the adjustment range larger.

[0073] Example 2

[0074] Reference Figure 2 This embodiment provides a mode-locking measurement device for a spatiotemporally mode-locked laser. The difference from Embodiment 1 is that one end of the first optical coupler 1 is also connected to a reference detection device 8; the splitting ratio of the first optical coupler 1 is 90:10; the first optical coupler 1 transmits 10% of the light to the reference detection device 8 for comparison with the light passed through the spatial sampling device, and transmits the other 90% of the light to the beam combiner 13 for spatial sampling; wherein, the first optical coupler is used to connect the spatiotemporally mode-locked fiber laser and the spatial sampling device and to split the laser to be tested.

[0075] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0076] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0077] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0078] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0079] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A mode-locking measurement device for spatiotemporal mode-locked lasers, characterized in that, It includes a spacetime mode-locked fiber laser, a spatial sampling device, and a detection device connected in sequence; The spatial sampling device includes a first optical coupler (1), a first collimator (2), a beam splitter (3), a first aperture (4), a second collimator (5), a second aperture (6), and a third collimator (7) connected in sequence. The beam splitter (3) forms a first spatial channel with the first aperture (4) and the second collimator (5); the beam splitter (3) forms a second spatial channel with the second aperture (6) and the third collimator (7); The first aperture (4) is movably disposed between the beam splitter (3) and the second collimator (5); the second aperture (6) is movably disposed between the beam splitter (3) and the third collimator (7); The second collimator (5) and the third collimator (7) are respectively connected to the detection device; the first optical coupler (1) is connected to the output end of the spatiotemporal mode-locked fiber laser.

2. The mode-locking measurement device for spatiotemporal mode-locked laser as described in claim 1, characterized in that, The first aperture (4) and the second aperture (6) have the same aperture; the apertures of the first aperture (4) and the second aperture (6) are smaller than the radius of the beam split by the beam splitter (3).

3. The mode-locking measurement device for spatiotemporal mode-locked lasers as described in claim 2, characterized in that, The first aperture (4) and the second aperture (6) are respectively disposed on the aperture base; the first aperture (4) and the second aperture (6) are variable apertures.

4. The mode-locking measurement device for spatiotemporal mode-locked laser as described in claim 1, characterized in that, The detection device includes a pulse information detection device and a spectral information detection device.

5. The mode-locking measurement device for spatiotemporal mode-locked laser as described in claim 1, characterized in that, The optical fiber used in the spatial sampling device is a passive multimode optical fiber; the beam splitter (3) has a splitting ratio of 50:

50.

6. The mode-locking measurement device for spatiotemporal mode-locked laser as described in claim 1, characterized in that, One end of the first optical coupler (1) is also connected to a reference detection device (8); the splitting ratio of the first optical coupler (1) is 90:

10.

7. The mode-locking measurement device for spatiotemporal mode-locked laser as described in claim 1, characterized in that, The spatiotemporal mode-locked fiber laser includes a first semiconductor saturable absorber mirror (9), a second optical coupler (10), a first polarization controller (11), a gain fiber (12), a beam combiner (13), a second polarization controller (14), and a second semiconductor saturable absorber mirror (15) connected in sequence. The end of the combiner (13) near the second semiconductor saturable absorber mirror (15) is also connected to a pump source (16); The splitting ratio of the second optical coupler (10) is adjustable, and the output end of the second optical coupler is connected to the first optical coupler (1).

8. The mode-locking measurement device for spatiotemporal mode-locked laser as described in claim 7, characterized in that, The spatiotemporal mode-locked fiber laser is an all-fiber laser; The first semiconductor saturable absorber mirror (9), the second optical coupler (10), and the first polarization controller (11) form the first optical fiber segment; The beam combiner (13), the second polarization controller (14), and the second semiconductor saturable absorber mirror (15) constitute the second optical fiber segment; The gain fiber (12) is fused to the first fiber segment.

9. The mode-locking measurement device for spatiotemporal mode-locked laser as described in claim 8, characterized in that, The core diameter of the optical fiber in the first optical fiber segment is larger than the core diameter of the gain optical fiber (12); the core diameter of the optical fiber in the second optical fiber segment is the same as the core diameter of the gain optical fiber (12); the first semiconductor saturable absorber mirror (9) and the second semiconductor saturable absorber mirror (15) are of the same model.

10. The mode-locking measurement device for spatiotemporal mode-locked laser as described in claim 9, characterized in that, The optical fiber in the first optical fiber segment is a graded-index multimode optical fiber; the optical fiber in the second optical fiber segment is a passive multimode optical fiber; and the gain optical fiber (12) is a ytterbium-doped optical fiber.

Images