Pulse-width-adjustable optical fiber picosecond seed source and working method thereof

Abstract

The invention relates to the technical field of lasers, and discloses a pulse-width-adjustable optical fiber picosecond seed source and a working method thereof. The pulse-width-adjustable optical fiber picosecond seed source comprises a semiconductor butterfly pump which generates pump light after being started; the filtering isolator is used for receiving the pump light from the semiconductor butterfly pump; the wavelength division multiplexer is used for coupling the pump light from the filtering isolator into the optical fiber annular cavity; the single-mode ytterbium-doped optical fiber is used for receiving the coupled pump light; the optical splitter I is used for splitting the signal light in the optical fiber annular cavity; the circulator is used for shunting the signal light in the optical fiber annular cavity into the two central wavelength adjustable gratings; a phase shifter for introducing a phase difference; the second optical splitter is used for splitting the adjusted signal light; and the filtering isolator is used for isolating the optical signal. Through the cooperative adjustment of the two central wavelength adjustable gratings, the synchronous control of the pulse width and the spectral width is realized, and the limitation that the pulse width can only be adjusted independently in the prior art is overcome. The spectrum overlapping area of the two gratings is effectively changed by adjusting the central wavelength of the gratings.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, and in particular to an optical fiber picosecond seed source with adjustable pulse width and a working method thereof. Background Art

[0002] In the field of ultrafast laser technology, picosecond seed sources, as an important component of mode-locked lasers, are widely used in scientific research, industrial processing, medical treatment and other fields. Traditional picosecond seed sources usually have a fixed pulse width and cannot be flexibly adjusted, which limits their adaptability in diverse applications. In order to achieve pulse width adjustment, external dispersion management systems are often used in the prior art, such as dispersion-adjustable chirped grating stretchers or adjustable spacing grating pairs, to achieve pulse width changes by stretching or compressing pulses.

[0003] However, these external dispersion management systems cannot synchronously adjust the spectral width. Although the pulse width can be adjusted by the dispersion management system, the system cannot simultaneously change the spectral width of the pulse, which limits its effectiveness in certain application scenarios. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a fiber picosecond seed source with adjustable pulse width and a working method thereof, which solves the problems that a dispersion-adjustable chirped grating stretcher can only change the pulse width but cannot change the spectral width, and requires a wide spectral width and high cost.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: an optical fiber picosecond seed source with adjustable pulse width, comprising:

[0006] Semiconductor butterfly pump: The pump light generated after startup, which serves as the energy source of the system, enters the filter isolator;

[0007] The filter isolator receives the pump light from the semiconductor butterfly pump, prevents the return light from entering the semiconductor butterfly pump, and makes the pump light flow unidirectionally to the wavelength division multiplexer;

[0008] A wavelength division multiplexer, which couples the pump light from the filter isolator into the fiber ring cavity, while allowing the signal light in the fiber ring cavity to continue to propagate;

[0009] The single-mode ytterbium-doped optical fiber receives the coupled pump light, absorbs the pump light and emits signal light through gain effect, and the signal light enters the optical fiber ring cavity;

[0010] Optical splitter 1 splits the signal light in the optical fiber ring cavity, a part of the signal light is used for mode locking, and the other part of the signal light continues to circulate in the optical fiber ring cavity;

[0011] A circulator, which splits the signal light in the fiber ring cavity into two central wavelength tunable gratings, so that the signal light between the two central wavelength tunable gratings is reflected and adjusted;

[0012] A phase shifter, used to introduce a phase difference and adjust the phase relationship of the signal light;

[0013] Optical splitter 2 is used to split the regulated signal light, a part of the split optical signal is output for external detection, and the other part of the optical signal continues to circulate in the optical fiber ring cavity;

[0014] A filter isolator, used to isolate the optical signal outputted to the outside by the second optical splitter;

[0015] Photoelectric probe, which monitors the mode-locking state in the optical fiber ring cavity in real time and generates a feedback signal;

[0016] The signal processing circuit is used for receiving the feedback signal provided by the photoelectric probe.

[0017] Preferably, the central wavelengths of the two central wavelength tunable gratings can be adjusted to change the spectral overlap region to adjust the pulse width of the output pulse.

[0018] Preferably, the two central wavelength tunable gratings are central wavelength tunable grating A and central wavelength tunable grating B, wherein the central wavelengths of the central wavelength tunable grating A and the central wavelength tunable grating B are a and c, respectively, and the spectral widths are b and d, respectively. By adjusting the values ​​of a, b, c, and d, the pulse width of the output pulse and the spectral width of the signal light are controlled.

[0019] Preferably, the phase shifter introduces different phase differences by means of an adjustable phase element arranged in the optical fiber ring cavity.

[0020] Preferably, the second optical splitter is connected to an external detection module, and the intensity of the output pulse of the optical signal outputted by the second optical splitter to the outside is adjusted through hardware circuit control.

[0021] Preferably, the photoelectric probe includes a plurality of detection units, each detection unit is used to detect different pulse parameters and transmit the detection results to a signal processing circuit, and the signal processing circuit is used to adjust the pulse width according to the detection results.

[0022] Preferably, the center wavelength tunable grating A and the center wavelength tunable grating B adjust the center wavelength through a mechanical or electric adjustment mechanism to achieve laser output of different wavelengths, and select the pulse output mode through a switching element integrated on the circuit board.

[0023] Preferably, a temperature control device is provided outside the optical fiber assembly of the optical fiber annular cavity, and the temperature control device adjusts the temperature through a thermistor and a heating element.

[0024] Preferably, a working method of an optical fiber picosecond seed source with adjustable pulse width comprises the following steps:

[0025] S1: Start the semiconductor butterfly pump source to provide pump energy;

[0026] S2: The pump light passes through the filter isolator to prevent the return light from interfering with the pump source and maintain stable unidirectional optical transmission;

[0027] S3: The pump light is coupled into the single-mode ytterbium-doped fiber through the wavelength division multiplexer. At this time, the ytterbium-doped fiber absorbs the pump light and emits the signal light.

[0028] S4: The emitted signal light enters the fiber ring cavity and is split by the optical splitter 1, and part of the optical signal is used for the mode locking process;

[0029] S5: The optical signal in the ring cavity passes through the circulator and is split to two central wavelength tunable gratings, including central wavelength tunable grating A and central wavelength tunable grating B;

[0030] S6: By adjusting the central wavelength of the central wavelength tunable gratings A and B, the spectral overlap area of ​​the two gratings is changed. This operation adjusts the pulse width and spectral width in the following ways:

[0031] When there are more spectral overlapping areas, the output pulse width becomes narrower;

[0032] When the spectral overlap area is small, the output pulse width becomes wider;

[0033] S7: The phase shifter introduces a phase difference to promote the mode locking process and stabilize the laser output;

[0034] S8: The output signal passes through the second optical splitter, 10% of the signal is extracted for external detection, and 90% of the signal continues to circulate in the ring cavity to maintain the mode-locked state;

[0035] S9: Isolate the output light through the filter isolator to prevent the return light from interfering with the mode locking process in the fiber ring cavity;

[0036] S10: The photoelectric probe monitors the mode-locking state and feeds back the mode-locking state information, and can further adjust the central wavelengths of the central wavelength tunable gratings A and B through the feedback signal to optimize the pulse width and spectral width of the system.

[0037] Preferably, the central wavelength tunable grating A and the central wavelength tunable grating B are respectively adjusted by independent electric drive systems.

[0038] The present invention provides an optical fiber picosecond seed source with adjustable pulse width, which has the following beneficial effects:

[0039] 1. The present invention realizes synchronous control of pulse width and spectrum width through the coordinated adjustment of two center wavelength tunable gratings, overcoming the limitation of the prior art that only pulse width can be adjusted separately. By adjusting the center wavelength of the grating, the spectral overlap area of ​​the two gratings can be effectively changed, so that the pulse width and spectrum width can be flexibly adjusted as needed to meet various application requirements.

[0040] 2. The present invention integrates the functions of adjusting pulse width and spectrum width into the fiber ring cavity, eliminating the need for complex external dispersion management systems (such as dispersion-adjustable chirped grating stretchers, etc.), greatly simplifying the system structure. At the same time, it reduces the use of external equipment and reduces the overall system cost.

[0041] 3. The present invention realizes stable mode-locking operation and provides high-quality pulse output by combining the ring cavity and the phase shifter. The phase shifter is used to introduce phase difference to ensure the phase consistency of the optical signal in the optical fiber cavity, thereby improving the system's mode-locking efficiency and the stability of the output pulse. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a light path diagram of an optical fiber device of an optical fiber picosecond seed source with adjustable pulse width according to the present invention;

[0043] Figure 2 It is a schematic diagram of the pulse width of the two central wavelength tunable gratings of the present invention when the overlap amount of the spectrum overlap region is large and the output pulse width is narrow;

[0044] Figure 3 It is a schematic diagram of the pulse width of the two central wavelength tunable gratings of the present invention when the overlap amount of the spectrum overlap region is small and the output pulse width is wide.

[0045] Among them, 1. Semiconductor butterfly pump; 2. 980nm filter isolator; 3. Wavelength division multiplexer; 4. Single-mode ytterbium-doped optical fiber; 5. 30:70 splitter 1; 6. circulator; 7. Center wavelength tunable grating A; 8. Center wavelength tunable grating B; 9. Phase shifter; 10. 10:90 splitter 2; 11. 1064nm filter isolator; 12. Photoelectric probe. DETAILED DESCRIPTION

[0046] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Please refer to the attached Figure 1 - Attachment Figure 3 The embodiment of the present invention provides an optical fiber picosecond seed source with adjustable pulse width, comprising:

[0048] Semiconductor butterfly pump 1: The pump light generated after startup, which serves as the energy source of the system, enters the 980nm filter isolator 2.

[0049] 980nm filter isolator 2: receives pump light from semiconductor butterfly pump 1, blocks return light from entering semiconductor butterfly pump 1, and makes pump light flow to wavelength division multiplexer 3 in one direction.

[0050] Wavelength division multiplexer 3: couples the pump light from the 980nm filter isolator 2 into the fiber ring cavity, while allowing the signal light in the fiber ring cavity to continue to propagate.

[0051] Single-mode ytterbium-doped fiber 4: receives the coupled pump light, absorbs the pump light and emits signal light through gain effect, and the signal light enters the fiber ring cavity.

[0052] 30:70 Splitter 5: Splits the signal light in the fiber ring cavity, one part of the signal light is used for mode locking, and the other part of the signal light continues to circulate in the fiber ring cavity.

[0053] Circulator 6: splits the signal light in the fiber ring cavity into two central wavelength tunable gratings, so that the signal light between the two central wavelength tunable gratings is reflected and adjusted.

[0054] Phase shifter 9: used to introduce a phase difference and adjust the phase relationship of the signal light.

[0055] 10:90 Optical splitter 2 10: used to split the regulated signal light, a part of the split optical signal is output for external detection, and the other part of the optical signal continues to circulate in the optical fiber ring cavity.

[0056] 1064nm filter isolator 11: used to isolate the optical signal outputted to the outside by the 10:90 optical splitter 10.

[0057] Photoelectric probe 12: monitors the mode-locking state in the optical fiber ring cavity in real time and generates a feedback signal.

[0058] Signal processing circuit: used for receiving the feedback signal provided by the photoelectric probe 12.

[0059] Specifically, the semiconductor butterfly pump 1 generates pump light after startup, and the pump light serves as the energy source of the system and enters the 980nm filter isolator 2. The semiconductor butterfly pump 1 is the main light source of the system and can stably output 980nm pump light to ensure the efficient operation of the fiber ring cavity in the system. The pump light has the characteristics of high efficiency and stability when working, and can provide continuous energy for the fiber cavity.

[0060] 980nm filter isolator 2: receives pump light from semiconductor butterfly pump 1, blocks return light from entering semiconductor butterfly pump 1, and makes pump light flow unidirectionally to wavelength division multiplexer 3. The main function of 980nm filter isolator 2 is to prevent reflected light in the ring cavity from interfering with the operation of the pump source, while ensuring unidirectional propagation of pump light and improving the stability of the system.

[0061] Wavelength division multiplexer 3: couples the pump light from the 980nm filter isolator 2 into the fiber ring cavity, while allowing the signal light in the fiber ring cavity to continue to propagate. Wavelength division multiplexer 3 realizes multi-wavelength transmission of pump light and signal light, so that optical signals can be efficiently transmitted in the same optical fiber, ensuring full utilization of pump light energy and stability of signal light.

[0062] Single-mode ytterbium-doped fiber 4: receives the coupled pump light, absorbs the pump light and emits the signal light through the gain effect, and the signal light enters the fiber ring cavity. Single-mode ytterbium-doped fiber 4 is the gain medium of the system, which can convert the 980nm pump light into the 1064nm signal light, ensuring that the signal light has sufficient intensity to support the subsequent mode locking process.

[0063] 30:70 Splitter-5: Splitting the signal light in the fiber ring cavity, a part of the signal light is used for mode locking, and the other part of the signal light continues to circulate in the fiber ring cavity. The function of 30:70 Splitter-5 is to control the distribution of signal light, ensuring that part of the signal light continues to propagate in the cavity to maintain energy balance, and the other part is used for mode locking operation.

[0064] Circulator 6: Divides the signal light in the fiber ring cavity into two central wavelength tunable gratings, so that the signal light between the two central wavelength tunable gratings is reflected and adjusted. The function of circulator 6 is to guide the signal light into different gratings and prevent the reflected light from flowing back into the system, ensuring that the light transmission direction of the system is consistent.

[0065] Phase shifter 9: used to introduce phase difference and adjust the phase relationship of the signal light. Phase shifter 9 optimizes the optical phase matching in the mode-locking process by adjusting the phase difference of the signal light, thereby improving the system's mode-locking efficiency and the stability of the pulse output.

[0066] 10:90 optical splitter 2 10: used to split the regulated signal light, a part of the optical signal after splitting is output for external detection, and the other part of the optical signal continues to circulate in the fiber ring cavity. 10:90 optical splitter 2 10 ensures that part of the output of the optical signal can be used for external analysis and detection, while 90% of the optical signal remains in the ring cavity to maintain the mode-locked state.

[0067] 1064nm filter isolator 11: used to isolate the optical signal output to the outside by the 10:90 optical splitter 10. The 1064nm filter isolator 11 can effectively block the return light, prevent the reflection of the external optical signal from affecting the stability of the ring cavity, and thus ensure the purity of the output signal.

[0068] Photoelectric probe 12: monitors the mode-locking state in the optical fiber ring cavity in real time and generates a feedback signal. The photoelectric probe 12 provides real-time feedback information by monitoring the intensity, pulse width and other parameters of the optical signal, which is used to adjust the system output and ensure the stability of the mode-locking process.

[0069] Signal processing circuit: used to receive the feedback signal provided by the photoelectric probe 12, and adjust the pulse width and spectrum width in the system according to the detection result. The signal processing circuit automatically adjusts the parameters of the central wavelength adjustable grating A7 and B8 according to the feedback signal to optimize the pulse output.

[0070] The central wavelengths of the two central wavelength tunable gratings can be adjusted to change the spectral overlap region so as to adjust the pulse width of the output pulse.

[0071] Specifically, the central wavelengths of the two central wavelength tunable gratings can be adjusted to change the spectral overlap region to adjust the pulse width of the output pulse. By adjusting the central wavelengths of the two gratings, precise pulse width control can be achieved to meet different application requirements.

[0072] The two central wavelength tunable gratings are central wavelength tunable grating A7 and central wavelength tunable grating B8, the central wavelengths of central wavelength tunable grating A7 and central wavelength tunable grating B8 are a and c, and the spectral widths are b and d, respectively. By adjusting the values ​​of a, b, c, and d, the pulse width of the output pulse and the spectral width of the signal light are controlled.

[0073] Specifically, the two center wavelength tunable gratings are center wavelength tunable grating A7 and center wavelength tunable grating B8, the center wavelengths of center wavelength tunable grating A7 and center wavelength tunable grating B8 are a and c, and the spectrum widths are b and d, respectively. By adjusting the values ​​of a, b, c, and d, the pulse width of the output pulse and the spectrum width of the signal light are controlled. By accurately adjusting the center wavelength and spectrum width, the system can adjust the pulse width and spectrum width according to different laser output requirements.

[0074] The phase shifter 9 introduces different phase differences through an adjustable phase element arranged in the optical fiber ring cavity.

[0075] Specifically, the phase shifter 9 introduces different phase differences through an adjustable phase element arranged in the optical fiber ring cavity. By accurately adjusting the phase shifter 9, the system can achieve dynamic adjustment of the optical phase, thereby further optimizing the coherence of the laser output.

[0076] 10:90 The optical splitter 10 is connected to the external detection module, and the intensity of the output pulse of the optical signal output by the optical splitter 10 to the outside is adjusted through hardware circuit control.

[0077] Specifically, the 10:90 optical splitter 2 10 is connected to the external detection module, and the intensity of the output pulse of the optical signal output to the outside by the 10:90 optical splitter 2 10 is adjusted through hardware circuit control. The external detection module monitors the output optical signal in real time and adjusts the intensity of the output pulse through the hardware circuit to maintain the stability of the output signal.

[0078] The photoelectric sensor 12 includes a plurality of detection units, each of which is used to detect different pulse parameters and transmit the detection results to the signal processing circuit, which is used to adjust the pulse width according to the detection results.

[0079] Specifically, the photoelectric probe 12 includes a plurality of detection units, each of which is used to detect different pulse parameters and transmit the detection results to the signal processing circuit, and the signal processing circuit is used to adjust the pulse width according to the detection results. The photoelectric probe 12 detects parameters such as pulse width, light intensity and frequency, and transmits the feedback signal to the signal processing circuit for precise adjustment.

[0080] The central wavelength tunable grating A7 and the central wavelength tunable grating B8 adjust the central wavelength through a mechanical or electric adjustment mechanism to achieve laser output of different wavelengths, and select the pulse output mode through a switching element integrated on the circuit board.

[0081] Specifically, the center wavelength tunable grating A7 and the center wavelength tunable grating B8 adjust the center wavelength through a mechanical or electric adjustment mechanism to achieve laser output of different wavelengths, and select the pulse output mode through a switching element integrated on the circuit board. The mechanical or electric adjustment mechanism can accurately adjust the center wavelength of the grating, thereby ensuring the accuracy and controllability of the laser output.

[0082] A temperature control device is arranged outside the optical fiber assembly of the optical fiber ring cavity, and the temperature control device adjusts the temperature through a thermistor and a heating element.

[0083] Specifically, a temperature control device is provided outside the optical fiber assembly of the optical fiber ring cavity, and the temperature control device adjusts the temperature through a thermistor and a heating element. The temperature control device ensures that the optical fiber assembly is always within the optimal operating temperature range, avoiding the influence of temperature fluctuations on optical signal transmission and system stability.

[0084] A working process of a fiber-optic picosecond seed source with adjustable pulse width includes the following steps:

[0085] S1: Start the semiconductor butterfly pump 1 to provide 980nm pump energy;

[0086] After the semiconductor butterfly pump 1 is started, it generates 980nm pump light, which provides sufficient energy for the system and supports the laser generation and amplification process in the fiber ring cavity.

[0087] S2: 980nm pump light passes through 980nm filter isolator 2 to avoid return light interfering with the pump source and maintain stable unidirectional optical transmission;

[0088] The pump light passes through the 980nm filter isolator 2 to prevent the reflected light in the fiber ring cavity from returning to the pump source, thereby ensuring stable output of the pump light and preventing damage or performance degradation caused by the return light.

[0089] S3: 980nm pump light is coupled into the single-mode ytterbium-doped fiber 4 through the wavelength division multiplexer 3. The ytterbium-doped fiber absorbs the pump light and emits 1064nm signal light.

[0090] The wavelength division multiplexer 3 effectively couples the 980 nm pump light with the 1064 nm signal light, and the single-mode ytterbium-doped optical fiber 4 absorbs the pump light and emits a 1064 nm laser signal through an excited state.

[0091] S4: The emitted 1064nm signal light enters the fiber ring cavity and is split by a 30:70 optical splitter-5, and part of the optical signal is used for the mode locking process;

[0092] The 30:70 optical splitter 5 splits the 1064nm laser signal, 30% of the optical signal enters the mode locking process, and 70% of the optical signal continues to circulate in the fiber ring cavity to ensure continuous and stable laser output.

[0093] S5: The optical signal in the ring cavity passes through the circulator 6 and is split to two central wavelength tunable gratings, including the central wavelength tunable grating A7 and the central wavelength tunable grating B8;

[0094] The circulator 6 splits the optical signal and guides it to the central wavelength tunable grating A7 and the central wavelength tunable grating B8 respectively, ensuring that the spectrum adjustment functions of the two gratings can be performed normally.

[0095] S6: By adjusting the central wavelengths of the central wavelength tunable grating A7 and the central wavelength tunable grating B8, the spectral overlap region of the two gratings is changed, thereby adjusting the pulse width and spectral width of the system:

[0096] When there are more spectral overlapping areas, the output pulse width becomes narrower;

[0097] When the spectral overlap area is small, the output pulse width becomes wider;

[0098] By synchronously adjusting the central wavelengths of the central wavelength tunable grating A7 and the central wavelength tunable grating B8, the spectral overlapping area of ​​the two gratings is changed, and then the pulse width and spectral width of the output pulse are adjusted to achieve flexible pulse width regulation.

[0099] S7: The phase shifter 9 introduces a phase difference to promote the mode locking process and stabilize the laser output;

[0100] The phase shifter 9 introduces a phase difference in the optical path, adjusts the phase matching of the optical signal, ensures the smooth progress of the mode locking process, and thus ensures the stability and coherence of the system laser output.

[0101] S8: The output signal passes through a 10:90 optical splitter, 10% of the signal is extracted for external detection, and 90% of the signal continues to circulate in the ring cavity to maintain the mode-locked state;

[0102] 10% of the output signal is extracted for external detection to detect important parameters such as pulse width and frequency. 90% of the optical signal continues to circulate in the fiber ring cavity to ensure the continuation of the mode-locked state.

[0103] S9: Isolate the output light through the 1064nm filter isolator 11 to prevent the return light from interfering with the mode locking process in the fiber ring cavity;

[0104] The 1064nm filter isolator 11 blocks the return light, ensuring the unidirectional transmission of the laser signal in the optical fiber ring cavity, preventing the return light from interfering with the mode locking process, and improving the system stability.

[0105] S10: The photoelectric probe 12 monitors the mode-locking state and feeds back the mode-locking state information, and further adjusts the central wavelengths of the central wavelength tunable grating A7 and the central wavelength tunable grating B8 through the feedback signal to optimize the pulse width and spectrum width of the system.

[0106] The photoelectric probe 12 monitors the system mode locking state in real time and provides feedback signals to automatically adjust the central wavelengths of the central wavelength tunable grating A7 and the central wavelength tunable grating B8 to optimize the pulse width and spectrum width, ensuring that the system is always in the best working state.

[0107] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An optical fiber picosecond seed source with adjustable pulse width, characterized in that: include: Semiconductor butterfly pump: The pump light generated after startup, which serves as the energy source of the system, enters the filter isolator; The filter isolator receives the pump light from the semiconductor butterfly pump, prevents the return light from entering the semiconductor butterfly pump, and makes the pump light flow unidirectionally to the wavelength division multiplexer; A wavelength division multiplexer, which couples the pump light from the filter isolator into the fiber ring cavity, while allowing the signal light in the fiber ring cavity to continue to propagate; The single-mode ytterbium-doped optical fiber receives the coupled pump light, absorbs the pump light and emits signal light through gain effect, and the signal light enters the optical fiber ring cavity; Optical splitter 1 splits the signal light in the optical fiber ring cavity, a part of the signal light is used for mode locking, and the other part of the signal light continues to circulate in the optical fiber ring cavity; A circulator, which splits the signal light in the fiber ring cavity into two central wavelength tunable gratings, so that the signal light between the two central wavelength tunable gratings is reflected and adjusted; A phase shifter, used to introduce a phase difference and adjust the phase relationship of the signal light; Optical splitter 2 is used to split the regulated signal light, a part of the split optical signal is output for external detection, and the other part of the optical signal continues to circulate in the optical fiber ring cavity; A filter isolator, used to isolate the optical signal outputted to the outside by the second optical splitter; Photoelectric probe, which monitors the mode-locking state in the optical fiber ring cavity in real time and generates a feedback signal; The signal processing circuit is used for receiving the feedback signal provided by the photoelectric probe.

2. The optical fiber picosecond seed source with adjustable pulse width according to claim 1, characterized in that: The central wavelengths of the two central wavelength tunable gratings can be adjusted to change the spectral overlap region to adjust the pulse width of the output pulse.

3. The optical fiber picosecond seed source with adjustable pulse width according to claim 2, characterized in that: The two central wavelength tunable gratings are central wavelength tunable grating A and central wavelength tunable grating B, wherein the central wavelengths of the central wavelength tunable grating A and the central wavelength tunable grating B are a and c, respectively, and the spectral widths are b and d, respectively. By adjusting the values ​​of a, b, c, and d, the pulse width of the output pulse and the spectral width of the signal light are controlled.

4. The optical fiber picosecond seed source with adjustable pulse width according to claim 1, characterized in that: The phase shifter introduces different phase differences through an adjustable phase element arranged in the optical fiber ring cavity.

5. The optical fiber picosecond seed source with adjustable pulse width according to claim 1, characterized in that: The second optical splitter is connected to the external detection module, and the intensity of the output pulse of the optical signal outputted by the second optical splitter to the outside is adjusted through hardware circuit control.

6. The optical fiber picosecond seed source with adjustable pulse width according to claim 1, characterized in that: The photoelectric probe includes a plurality of detection units, each detection unit is used to detect different pulse parameters and transmit the detection results to the signal processing circuit, and the signal processing circuit is used to adjust the pulse width according to the detection results.

7. The optical fiber picosecond seed source with adjustable pulse width according to claim 3, characterized in that: The central wavelength tunable grating A and the central wavelength tunable grating B can adjust the central wavelength through a mechanical or electric adjustment mechanism to achieve laser output of different wavelengths, and select the pulse output mode through a switching element integrated on the circuit board.

8. The optical fiber picosecond seed source with adjustable pulse width according to claim 1, characterized in that: A temperature control device is arranged outside the optical fiber assembly of the optical fiber annular cavity, and the temperature control device adjusts the temperature through a thermistor and a heating element.

9. A working method of an optical fiber picosecond seed source with adjustable pulse width, characterized in that: An optical fiber picosecond seed source with adjustable pulse width as claimed in any one of claims 1 to 8 comprises the following steps: S1: Start the semiconductor butterfly pump source to provide pump energy; S2: The pump light passes through the filter isolator to prevent the return light from interfering with the pump source and maintain stable unidirectional optical transmission; S3: The pump light is coupled into the single-mode ytterbium-doped fiber through the wavelength division multiplexer. At this time, the ytterbium-doped fiber absorbs the pump light and emits the signal light. S4: The emitted signal light enters the fiber ring cavity and is split by the optical splitter 1, and part of the optical signal is used for the mode locking process; S5: The optical signal in the ring cavity passes through the circulator and is split to two central wavelength tunable gratings, including central wavelength tunable grating A and central wavelength tunable grating B; S6: By adjusting the central wavelength of the central wavelength tunable gratings A and B, the spectral overlap area of ​​the two gratings is changed. This operation adjusts the pulse width and spectral width in the following ways: When there are more spectral overlapping areas, the output pulse width becomes narrower; When the spectral overlap area is small, the output pulse width becomes wider; S7: The phase shifter introduces a phase difference to promote the mode locking process and stabilize the laser output; S8: The output signal passes through the second optical splitter, 10% of the signal is extracted for external detection, and 90% of the signal continues to circulate in the ring cavity to maintain the mode-locked state; S9: Isolate the output light through the filter isolator to prevent the return light from interfering with the mode locking process in the fiber ring cavity; S10: The photoelectric probe monitors the mode-locking state and feeds back the mode-locking state information, and can further adjust the central wavelengths of the central wavelength tunable gratings A and B through the feedback signal.

10. The working method of the optical fiber picosecond seed source with adjustable pulse width according to claim 9, characterized in that: The central wavelength tunable grating A and the central wavelength tunable grating B are respectively capable of adjusting the central wavelengths through independent electric drive systems.

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