Automatic bidirectional mode-locking fiber laser system

Abstract

The invention provides an automatic bidirectional mode-locking fiber laser system, and relates to the technical field of fiber lasers. The system comprises a first electric polarization controller, a second wavelength division multiplexer and a second gain optical fiber which are connected in sequence to form a first gain branch used for realizing laser amplification and polarization state adjustment in an anti-clockwise direction; the second electric polarization controller, the first wavelength division multiplexer and the first gain optical fiber are sequentially connected to form a second gain branch for realizing laser amplification and polarization state adjustment in the clockwise direction; and the third electric polarization controller, the gold nano film and the optical coupler are sequentially connected to form a common branch for simultaneously realizing automatic bidirectional mode locking in the clockwise direction and the anticlockwise direction. The automatic bidirectional mode-locking fiber laser system based on a genetic algorithm and a feedforward neural network is adopted to realize automatic searching and long-term maintenance of a bidirectional single soliton mode-locking state, and is suitable for the fields of double-comb spectrum, double-comb distance measurement, precision spectroscopy and light source programming.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fiber lasers, more particularly, to an automatic bidirectional mode-locked fiber laser system. BACKGROUND

[0002] Bidirectional mode-locked fiber lasers have unique advantages such as providing two coherent laser pulses directly, good beam quality, high peak power, flexible and compact structure, and low maintenance cost, and are widely used in fields such as double comb spectrum, double comb ranging, and precision spectroscopy. With the increasing demand for manufacturing precision and the deepening of scientific research, higher requirements are put forward for the output stability, anti-interference ability and dynamic response speed of the laser.

[0003] In a bidirectional mode-locked fiber laser, due to the gain competition and interaction between the counter-propagating pulses in the same cavity, stable bidirectional single soliton mode-locking usually requires high-intensity trial-and-error manual adjustment in a high-dimensional parameter space of multi-dimensional polarization states, which is time-consuming and has poor reproducibility. Existing laser systems can only achieve passive bidirectional mode-locking, or manually adjust the state of the polarizer to achieve bidirectional mode-locking.

[0004] In addition, environmental disturbances easily lead to mode-locking loss, and existing automated methods focus on single-direction mode-locking, which can only achieve automatic mode-locking in one direction, and it is still difficult to simultaneously consider the rapid search, single soliton state recognition and long-term stable state maintenance of bidirectional mode-locking. Since a bidirectional mode-locked laser system needs to establish and stabilize mode-locked pulses propagating in two directions in the same laser cavity, there is currently no research on intelligent methods applied to bidirectional mode-locked laser systems to achieve bidirectional automatic mode-locking.

[0005] Therefore, there is an urgent need for a control system applied to bidirectional mode-locked fiber lasers to solve the problems of existing bidirectional mode-locked fiber lasers, such as response lag in spectral stability and mode-locking reliability, significant gain competition of bidirectional pulses, poor state controllability, and lack of intelligent recognition and recovery capabilities. SUMMARY

[0006] To solve the problems in the background art, the present application provides an automatic bidirectional mode-locked fiber laser system to solve the defects of the bidirectional mode-locked fiber laser in the prior art.

[0007] The technical solution of the present application to solve the above technical problems is as follows: An automatic bidirectional mode-locked fiber laser system, comprising: a laser resonator composed of a first pump source, a first wavelength division multiplexer, a first gain fiber, a first three-port circulator, a first electrically controlled polarization controller, a second wavelength division multiplexer, a second pump source, a second gain fiber, a second three-port circulator, a second electrically controlled polarization controller, a third electrically controlled polarization controller, a gold nanometer film, and an optical coupler; and a cavity-out measurement branch composed of a first optical isolator, a second optical isolator, a third three-port circulator, a fourth three-port circulator, a dispersion compensation fiber, a high-speed oscilloscope, and a computer system. The first electrically controlled polarization controller, the second wavelength division multiplexer, and the second gain fiber are sequentially connected to form a first gain branch, which is used for realizing laser amplification and polarization state adjustment in the counterclockwise direction. The second electrically controlled polarization controller, the first wavelength division multiplexer, and the first gain fiber are sequentially connected to form a second gain branch, which is used for realizing laser amplification and polarization state adjustment in the clockwise direction. The third electrically controlled polarization controller, the gold nanometer film, and the optical coupler are sequentially connected to form a common branch, which is used for simultaneously realizing automatic bidirectional mode-locking in the clockwise and counterclockwise directions. The computer system internally runs a two-stage genetic algorithm, which simultaneously controls the first electrically controlled polarization controller, the second electrically controlled polarization controller, and the third electrically controlled polarization controller by using the first-stage genetic algorithm to realize one-direction mode-locking in the clockwise or counterclockwise direction; when one-direction mode-locking is realized, the second-stage genetic algorithm is entered, and the first electrically controlled polarization controller and the second electrically controlled polarization controller are simultaneously controlled to realize simultaneous mode-locking in the clockwise and counterclockwise directions.

[0008] Preferably, the output end of the first pump source is connected with the first input end of the first wavelength division multiplexer, the output end of the first wavelength division multiplexer is connected with the input end of the first gain optical fiber, the output end of the first gain optical fiber is connected with the first port of the first three-port circulator, the third port of the first three-port circulator is connected with the input end of the first electrically controlled polarization controller, the output end of the first electrically controlled polarization controller is connected with the first input end of the second wavelength division multiplexer, the output end of the second wavelength division multiplexer is connected with the input end of the second gain optical fiber, the output end of the second gain optical fiber is connected with the first port of the second three-port circulator, the third port of the second three-port circulator is connected with the input end of the second electrically controlled polarization controller, the output end of the second electrically controlled polarization controller is connected with the second input end of the first wavelength division multiplexer, the second port of the first three-port circulator is connected with the input end of the third electrically controlled polarization controller, the output end of the third electrically controlled polarization controller is connected with the input end of the gold nanometer film, the output end of the gold nanometer film is connected with the input end of the first optical coupler, the first output end of the first optical coupler is connected with the second port of the second three-port circulator, the second output end of the first optical coupler is connected with the input end of the first optical isolator, the third output end of the first optical coupler is connected with the input end of the second optical isolator, the output end of the first optical isolator is connected with the first port of the third three-port circulator, the output end of the second optical isolator is connected with the first port of the fourth three-port circulator, the second port of the third three-port circulator is connected with the input end of the dispersion compensation optical fiber, the output end of the dispersion compensation optical fiber is connected with the second port of the fourth three-port circulator, the third port of the third three-port circulator is connected with the first input end of the high-speed oscilloscope for real-time monitoring of the frequency domain and time domain characteristics in the clockwise direction, the third output end of the fourth three-port circulator is connected with the second input end of the high-speed oscilloscope for real-time monitoring of the frequency domain and time domain characteristics in the counterclockwise direction, the output end of the high-speed oscilloscope is connected with the input end of the computer system, and the output end of the computer system is connected with the first electrically controlled polarization controller, the second electrically controlled polarization controller, and the third electrically controlled polarization controller, so as to realize closed-loop feedback control.

[0009] Preferably, the waveform characteristics of the bidirectional mode-locked laser after time stretching by the dispersion compensation optical fiber are measured to construct a fitness function, and a trained feedforward neural network is combined to find a stable bidirectional single-soliton mode-locked state.

[0010] Preferably, the comprehensive fitness function F of the two-stage genetic algorithm is: ; wherein, fitness function for clockwise direction, fitness function for counter-clockwise direction; fitness function for each direction define i as cw or ccw for clockwise or counter-clockwise direction, wherein, , is a weight coefficient; is the radio frequency spectrum intensity captured by the high-speed oscilloscope; is the time domain uniformity index captured by the high-speed oscilloscope.

[0011] Preferably, the feedforward neural network comprises in sequence: an input layer of 91 nodes, three hidden layers with node numbers of 120, 50 and 20 respectively, and an output layer of 1 node, and single soliton mode-locking is optimized by the feedforward neural network, so that single soliton pulse stable mode-locking in clockwise and counter-clockwise directions is finally realized.

[0012] Preferably, the computer system is used to realize long-term stable maintenance and disturbance recovery of the system, after single soliton pulse stable mode-locking in clockwise and counter-clockwise directions is realized, the system updates state measurement every 10 s and continuously monitors the running state, under temperature drift and mechanical disturbance, the system is out of the state of bidirectional single soliton pulse mode-locking, and the optimization of genetic algorithm and feedforward neural network is re-performed to recover the state of bidirectional single soliton pulse mode-locking, so that sustainable automatic operation is realized.

[0013] The present application has the following advantages: (1) The branch branch paths respectively comprising three electric polarization controllers are provided, non-common gain paths are respectively arranged in clockwise and counter-clockwise directions, so as to suppress the gain competition in two directions and improve the stability; the first electric polarization controller and the second electric polarization controller of the non-common gain path are used to adjust the birefringence of the two gain branches, and the third electric polarization controller of the common path is used to adjust the birefringence of the common branch; the electric polarization controller realizes intelligent regulation and control of the polarization state through a computer closed-loop feedback control system.

[0014] (2) The all-fiber mode-locked mechanism based on the gold nanometer film saturable absorber is adopted, which shows fast response time and significant surface plasmon resonance characteristics, and forms bidirectional soliton pulses; the saturable absorber is used to cooperate with the three electric polarization controllers to realize bidirectional mode-locking; the dispersion compensation fiber linearly maps the spectral information to the time domain waveform, and the high-speed oscilloscope directly captures and restores the instantaneous spectral distribution of the laser, breaks through the speed limit of the traditional spectrometer, realizes real-time spectral reconstruction at the microsecond level, and provides reference physical quantities for the optimization of the genetic algorithm and the feedforward neural network.

[0015] ​(3) The computer system reads the frequency domain feedback in real time based on the high-speed oscilloscope, generates control instructions based on the target frequency domain characteristics and spectral shape through genetic algorithm and feedforward neural network, optimizes the objective function by adding a time domain uniformity index captured by the high-speed oscilloscope in the fitness function, outputs the optimal polarization control instructions, and realizes precise closed-loop control.

[0016] (4) The control vector in the two-stage genetic algorithm optimization problem includes the first electric polarization controller, the second electric polarization controller and the third electric polarization controller; the first-stage genetic algorithm controls the first electric polarization controller, the second electric polarization controller and the third electric polarization controller at the same time to realize at least one direction mode-locked; when one direction mode-locked is realized, the second-stage genetic algorithm is entered, and the first electric polarization controller and the second electric polarization controller are controlled at the same time to realize clockwise and counterclockwise bidirectional automatic mode-locked, closed-loop driving electric polarization controller, realizing multi-parameter collaborative control, breaking through the single adjustment mechanism of traditional mode-locked.

[0017] (5) When bidirectional single soliton pulse mode-locked is realized, the system will update the state measurement once every 10 s and continuously monitor the running state. Under the influence of temperature drift, mechanical disturbance and other environmental disturbances, the system deviates from the bidirectional single soliton pulse mode-locked state, and will re-optimize the genetic algorithm and feedforward neural network and restore the bidirectional single soliton pulse mode-locked state to realize sustainable automatic operation. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to make the present application more easily understood, the present application will be described in more detail by referring to the specific embodiments shown in the drawings. These drawings only depict typical embodiments of the present application and should not be considered as limiting the scope of protection of the present application.

[0019] Figure 1 is a cavity structure schematic diagram of an automatic bidirectional mode-locked fiber laser system provided by an embodiment of the present application; Figure 2 is an automatic bidirectional mode-locked fiber laser output bidirectional single pulse soliton mode-locked schematic diagram based on two-stage genetic algorithm and feedforward neural network provided by an embodiment of the present application.

[0020] Reference signs: 1 - first pump source, 2 - first wavelength division multiplexer, 3 - first gain fiber, 4 - first three-port circulator, 5 - first electrically controlled polarization controller, 6 - second wavelength division multiplexer, 7 - second pump source, 8 - second gain fiber, 9 - second three-port circulator, 10 - second electrically controlled polarization controller, 11 - third electrically controlled polarization controller, 12 - gold nanometer film, 13 - optical coupler, 14 - first optical isolator, 15 - second optical isolator, 16 - third three-port circulator, 17 - fourth three-port circulator, 18 - dispersion compensation fiber, 19 - high-speed oscilloscope, 20 - computer system. DETAILED DESCRIPTION

[0021] Embodiments of the present application are described below with reference to the accompanying drawings, so that those skilled in the art can better understand the present application and implement it, but the listed examples are not intended to limit the present application, and the examples described below and the technical features in the examples can be combined with each other without conflict, wherein the same components are denoted by the same reference numerals. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] The present application provides an automatic bidirectional mode-locked fiber laser system, Figure 1 A structure schematic diagram of an automatic bidirectional mode-locked fiber laser system provided for an example is shown in the figure.

[0023] Referring to Figure 1 In the embodiment of the present application, the automatic bidirectional mode-locked fiber laser system based on genetic algorithm and feedforward neural network comprises: a first pump source 1, a first wavelength division multiplexer 2, a first gain fiber 3, a first three-port circulator 4, a first electrically controlled polarization controller 5, a second wavelength division multiplexer 6, a second pump source 7, a second gain fiber 8, a second three-port circulator 9, a second electrically controlled polarization controller 10, a third electrically controlled polarization controller 11, a gold nanometer film 12, an optical coupler 13, a first optical isolator 14, a second optical isolator 15, a third three-port circulator 16, a fourth three-port circulator 17, a dispersion compensation fiber 18, a high-speed oscilloscope 19, and a computer system 20. The output end of the first pump source 1 provides pump to the first gain optical fiber 3 through the first wavelength division multiplexer 2, the output end of the first gain optical fiber 3 is connected with the third electric polarization controller 11 in turn, the third electric polarization controller 11 is connected with the saturable absorber formed by the gold nanometer film 12, and then is connected with the second three-port circulator 9 through the first optical coupler 13, the second three-port circulator 9 is connected with the second electric polarization controller 10, and is connected back to the resonant cavity through the first wavelength division multiplexer 2, so as to form a clockwise closed loop propagation link; the output end of the second pump source 7 provides pump to the second gain optical fiber 8 through the second wavelength division multiplexer 6, the output end of the second gain optical fiber 8 is connected with the first optical coupler 13 in turn, the first optical coupler 13 is connected with the saturable absorber formed by the gold nanometer film 12, and then is connected with the first three-port circulator 4 through the third electric polarization controller 11, the first three-port circulator 4 is connected with the first electric polarization controller 5, and is connected back to the resonant cavity through the second wavelength division multiplexer 6, so as to form an anticlockwise closed loop propagation link.

[0024] The first electric polarization controller 5, the second wavelength division multiplexer 6 and the second gain optical fiber 8 are connected in sequence to form a first gain branch, for realizing laser amplification and polarization state adjustment in the anticlockwise direction. The second electric polarization controller 10, the first wavelength division multiplexer 2 and the first gain optical fiber 3 are connected in sequence to form a second gain branch, for realizing laser amplification and polarization state adjustment in the clockwise direction. The third electric polarization controller 11, the gold nanometer film 12 and the optical coupler 13 are connected in sequence to form a common branch, for simultaneously realizing automatic bidirectional mode locking in the clockwise direction and the anticlockwise direction.

[0025] It is worth mentioning that the saturable absorber based on the gold nanometer film 12 has fast response time and significant surface plasmon resonance characteristics, and forms bidirectional soliton pulses, and there are non-common gain paths in the clockwise direction and the anticlockwise direction, so as to suppress bidirectional gain competition and improve stability. The first electric polarization controller 5 and the second electric polarization controller 10 of the non-common gain path are used for adjusting the birefringence of the two gain branches, and the third electric polarization controller 11 of the common path is used for adjusting the birefringence of the common branch.

[0026] In the present application, two-way output of the first optical coupler 13 is connected to the third three-port circulator 16 and the fourth three-port circulator 17 through the first optical isolator 14 and the second optical isolator 15 respectively, and is connected to the dispersion compensation fiber 18 to realize time-stretching dispersion Fourier transform, the output of the dispersion compensation fiber 18 is connected to the input of the high-speed oscilloscope 19 through the third three-port circulator 16 and the fourth three-port circulator 17 respectively, to realize synchronous acquisition of signals in clockwise and counterclockwise directions, the output of the high-speed oscilloscope 19 is connected to the computer system, and the computer system is connected to the first electric polarization controller, the second electric polarization controller and the third electric polarization controller, to realize closed-loop feedback control.

[0027] It is worth mentioning that the dispersion compensation fiber 18 performs time-stretching dispersion Fourier transform on the clockwise and counterclockwise pulses to obtain frequency domain signals and synchronously acquires pulse sequences, a genetic algorithm fitness function is constructed from radio frequency spectrum intensity and time domain uniformity indexes, and the comprehensive fitness function F of the two-stage genetic algorithm is: ; Among them, is the clockwise direction fitness function, is the counterclockwise direction fitness function.

[0028] Fitness function of genetic algorithm The clockwise / counterclockwise direction is defined as: ; Among them, , is a weight coefficient; is the radio frequency spectrum intensity captured by the high-speed oscilloscope; is the time domain uniformity index captured by the high-speed oscilloscope.

[0029] Please refer to Figure 2 , Figure 2 is the automatic bidirectional mode-locked fiber laser output bidirectional single soliton pulse control schematic diagram in the embodiment of the present application. The first-stage genetic algorithm sets a large population size and iteration number to cover a wide parameter space, and controls the first electric polarization controller, the second electric polarization controller and the third electric polarization controller to realize at least one direction locking; when one direction locking is realized, the second-stage genetic algorithm is entered for local fine adjustment, the corresponding electric polarization controller in the locked direction is controlled for local search and the corresponding electric polarization controller in the un-locked direction is controlled for global search, to realize clockwise and counterclockwise simultaneous locking and enter the feedforward neural network discrimination.

[0030] It is worth mentioning that the feedforward neural network input spectrum shape feature, using an input layer 91 nodes, three hidden layers, node number is 120 / 50 / 20 respectively, output layer 1 node feedforward neural network, real-time classification optimization of single soliton, Q-switched mode-locked, soliton molecule and other states, when non-single soliton pulse mode-locked characteristics appear, the system continues to optimize the genetic algorithm until it enters the bidirectional single soliton pulse mode-locked state.

[0031] In another embodiment of the application, when the bidirectional single soliton pulse mode-locked state is achieved, the system will update the state measurement every 10 s and continuously monitor the running state, and when the system deviates from the bidirectional single soliton pulse mode-locked state due to temperature drift, mechanical disturbance and other environmental disturbances, the system will re-optimize the genetic algorithm and feedforward neural network and restore the bidirectional single soliton pulse mode-locked state, achieving sustainable automatic operation.

[0032] The application sets up branch branches respectively including three electric polarization controllers, non-common gain paths are respectively set in clockwise and counterclockwise directions to suppress bidirectional gain competition and improve stability; the first electric polarization controller and the second electric polarization controller of the non-common gain path are used to adjust the birefringence of the two gain branches, and the third electric polarization controller of the common path is used to adjust the birefringence of the common branch; the electric polarization controller realizes intelligent regulation and control of the polarization state through a computer closed-loop feedback control system. The all-fiber mode-locked mechanism based on the gold nanometer film saturable absorber shows fast response time and significant surface plasmon resonance characteristics, forming bidirectional soliton pulses; the saturable absorber is used to cooperate with the three electric polarization controllers to realize bidirectional mode-locking; the dispersion compensation fiber linearly maps the spectral information to the time domain waveform, and the high-speed oscilloscope directly captures and restores the instantaneous spectral distribution of the laser, breaking through the speed limit of the traditional spectrometer, realizing real-time spectral reconstruction at the microsecond level, and providing reference physical quantities for the optimization of the genetic algorithm and the feedforward neural network. The computer system reads the frequency domain feedback in real time based on the high-speed oscilloscope, generates control instructions based on the target frequency domain characteristics and spectral shape through the genetic algorithm and the feedforward neural network, adds a time domain uniformity index captured by the high-speed oscilloscope in the fitness function to optimize the objective function, and outputs the optimal polarization control instruction, realizing precise closed-loop control to realize intelligent control of automatic bidirectional mode-locking.

[0033] In the application, each embodiment is described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same and similar parts between each embodiment can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the related parts can be referred to the method part.

[0034] The above-described embodiments are merely preferred specific embodiments of the present application, which can be referred to as one or more of the same or different embodiments according to the present disclosure. The usual changes and replacements made by those skilled in the art within the scope of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. An automated bidirectional mode-locked fiber laser system, characterized in that, The application relates to a laser resonator and a cavity-out measurement branch. The first electric polarization controller, the second wave division multiplexer and the second gain optical fiber are sequentially connected to form a first gain branch, which is used for realizing laser amplification and polarization state adjustment in the counterclockwise direction. The second electric polarization controller, the first wave division multiplexer and the first gain optical fiber are sequentially connected to form a second gain branch, which is used for realizing laser amplification and polarization state adjustment in the clockwise direction. The third electric polarization controller, the gold nanometer film and the optical coupler are sequentially connected to form a common branch, which is used for realizing automatic bidirectional mode locking in the clockwise direction and the counterclockwise direction. The computer system internally runs a two-stage genetic algorithm, the first-stage genetic algorithm is used for simultaneously controlling the first electric polarization controller, the second electric polarization controller and the third electric polarization controller, so as to realize one-direction mode locking in the clockwise direction or the counterclockwise direction; when one-direction mode locking is realized, the second-stage genetic algorithm is entered, and the first electric polarization controller and the second electric polarization controller are simultaneously controlled, so as to realize simultaneous mode locking in the clockwise direction and the counterclockwise direction. ​ 2. The automated bidirectional mode-locked fiber laser system of claim 1, wherein, The output end of the first pump source is connected with the first input end of the first wavelength division multiplexer, the output end of the first wavelength division multiplexer is connected with the input end of the first gain optical fiber, the output end of the first gain optical fiber is connected with the first port of the first three-port circulator, the third port of the first three-port circulator is connected with the input end of the first electrically controlled polarization controller, the output end of the first electrically controlled polarization controller is connected with the first input end of the second wavelength division multiplexer, the output end of the second wavelength division multiplexer is connected with the input end of the second gain optical fiber, the output end of the second gain optical fiber is connected with the first port of the second three-port circulator, the third port of the second three-port circulator is connected with the input end of the second electrically controlled polarization controller, the output end of the second electrically controlled polarization controller is connected with the second input end of the first wavelength division multiplexer, the second port of the first three-port circulator is connected with the input end of the third electrically controlled polarization controller, the output end of the third electrically controlled polarization controller is connected with the input end of the gold nanometer film, the output end of the gold nanometer film is connected with the input end of the first optical coupler, the first output end of the first optical coupler is connected with the second port of the second three-port circulator, the second output end of the first optical coupler is connected with the input end of the first optical isolator, the third output end of the first optical coupler is connected with the input end of the second optical isolator, the output end of the first optical isolator is connected with the first port of the third three-port circulator, the output end of the second optical isolator is connected with the first port of the fourth three-port circulator, the second port of the third three-port circulator is connected with the input end of the dispersion compensation optical fiber, the output end of the dispersion compensation optical fiber is connected with the second port of the fourth three-port circulator, the third port of the third three-port circulator is connected with the first input end of the high-speed oscilloscope for real-time monitoring of the frequency domain and time domain characteristics in the clockwise direction, the third output end of the fourth three-port circulator is connected with the second input end of the high-speed oscilloscope for real-time monitoring of the frequency domain and time domain characteristics in the counterclockwise direction, the output end of the high-speed oscilloscope is connected with the input end of the computer system, and the output end of the computer system is connected with the first electrically controlled polarization controller, the second electrically controlled polarization controller and the third electrically controlled polarization controller, so as to realize closed-loop feedback control.

3. The automated bidirectional mode-locked fiber laser system of claim 2, wherein, The waveform characteristics of the bidirectional mode-locked laser after time stretching by the dispersion compensation optical fiber are measured to construct a fitness function, and a stable bidirectional single soliton mode-locked state is found by combining a trained feedforward neural network.

4. The automated bidirectional mode-locked fiber laser system of claim 3, wherein, The comprehensive fitness function F of the two-stage genetic algorithm is: ； wherein, is a clockwise fitness function, is a counter-clockwise fitness function; fitness function for each direction define i as cw or ccw for clockwise or counter-clockwise direction, respectively, ； wherein, , is a weight coefficient; is the radio frequency intensity captured by the high-speed oscilloscope; is the time domain uniformity index captured by the high-speed oscilloscope.

5. The automated bidirectional mode-locked fiber laser system of claim 4, wherein, The feedforward neural network comprises an input layer of 91 nodes, three hidden layers with node numbers of 120, 50 and 20 respectively, and an output layer of 1 node, and the single soliton mode-locked state is optimized by the feedforward neural network, so that the clockwise and counterclockwise single soliton pulses are stably mode-locked at the same time.

6. The automatic bidirectional mode-locked fiber laser system of any one of claims 1 to 5, wherein, The computer system is used to realize system long-term stable maintenance and disturbance recovery, after the stable mode-locked of single soliton pulse in clockwise and counterclockwise direction, the system updates the state measurement every 10 s and continuously monitors the running state, under the temperature drift and mechanical disturbance, the system deviates from the bidirectional single soliton pulse mode-locked state, re-optimizes the genetic algorithm and the feedforward neural network and recovers the bidirectional single soliton pulse mode-locked state, and realizes the sustainable automatic operation.

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