Laser soliton explosion pre-judgment and active suppression method and system based on real-time monitoring

Abstract

The invention discloses a laser soliton explosion pre-judgment and active suppression method and system based on real-time monitoring, and provides a three-level control architecture for solving the problem that a device is damaged due to sudden soliton explosion of a mode-locked fiber laser in a stable operation stage. Comprising the following steps: capturing an optical power signal in real time by using a high-speed photoelectric detector, converting the optical power signal into an electric signal, inputting the electric signal into a laser power control system, and judging whether threshold power is exceeded and performing abnormal power gradient analysis by a calculation module based on a control algorithm; and the attenuation coefficient obtained by the calculation module outputs a driving voltage through a digital-to-analog converter to drive an acousto-optic modulator (AOM), so that incident light is attenuated according to a target value through the AOM, and the regulation and control of the intra-cavity power are further achieved. The problems that a traditional method is slow in response and extensive in control are solved, and reliable protection is provided for the ultrafast laser.

Description

Technical Field

[0001] This invention relates to the field of ultrafast laser technology, specifically to a method and system for predicting and actively suppressing laser soliton explosions based on real-time monitoring. It is particularly suitable for solving the problem of device damage and processing misalignment caused by sudden soliton explosions in full-power lasers in industrial scenarios, and is applicable to scenarios such as laser welding and precision machining. Background Technology

[0002] In the field of modern laser technology, ultrafast fiber lasers have attracted much attention due to their superior performance and broad application prospects. As an important branch of laser technology, ultrafast fiber lasers play an irreplaceable role in industrial processing, medical diagnosis, and precision measurement. However, in industrial fiber lasers operating at continuous full power, soliton explosions, characterized by a 10-20 fold increase in pulse energy within 100-200 ns and a peak power exceeding 1 kW, can damage optical components or degrade processing quality. The soliton explosion problem faced by these lasers during stable operation has always been a key challenge restricting their safe and stable operation.

[0003] Soliton explosions, as complex nonlinear phenomena, have multifaceted effects on fiber lasers. First, the high-power pulses generated during the explosion can directly damage fiber devices. Second, soliton explosions lead to instability in laser output, manifested as drastic fluctuations in output power. This not only affects the processing accuracy and efficiency of the laser but may also cause harmful byproducts such as thermal effects and stress waves. To address this issue, a real-time monitoring-based method for predicting and actively suppressing laser soliton explosions has been developed. This method can improve the reliability of ultrafast fiber lasers, extend their lifespan, and ensure safe system operation.

[0004] In recent years, various suppression methods have been proposed, including pump current regulation, mechanical attenuators, and pure software monitoring. However, all three methods have significant drawbacks. For example, pump current regulation requires reducing laser power, which is not feasible in industrial applications and violates the full-power operation requirements of industrial production lines. Mechanical attenuators have slow response speeds due to mechanical delays, making them ineffective at intercepting soliton explosions. Pure software monitoring is limited by signal delays, often lagging behind the explosion's development and resulting in "damage before control." Therefore, these methods are insufficient to meet the needs of high-performance fiber lasers. Industrial lasers must operate at full power, and traditional current regulation is not feasible. A fast-response method for controlling the rapid attenuation of optical power is urgently needed. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for predicting and actively suppressing laser soliton explosions based on real-time monitoring, addressing the aforementioned problems.

[0006] The technical solution of the present invention is as follows: A method for predicting and actively suppressing laser soliton explosions based on real-time monitoring includes the following steps: The output optical power of the laser is acquired in real time by a high-speed photodetector, and the optical signal is converted into an electrical signal. The electrical signal is transmitted to the laser power control system, which generates an attenuation control command based on the judgment result and calculates the driving voltage. The voltage value is transmitted to the AOM driver via a digital-to-analog converter, which drives the AOM to attenuate the transmitted light power. The laser power control system includes a signal acquisition layer, a data processing layer, and a power control layer. The signal acquisition layer receives the electrical signal output by the high-speed photodetector and converts the output analog electrical signal into a digital signal through an analog-to-digital converter for acquisition. The data processing layer uses a real-time control algorithm to calculate and analyze the acquired data to obtain attenuation control commands. The power control layer uses an analog-to-digital converter to transmit the voltage value to the AOM driver according to the attenuation control commands and the driving voltage. It then dynamically adjusts the AOM through radio frequency power to attenuate the pump output power before inputting it into the laser.

[0007] Using the above method, the computational processing in the laser power control system employs a control algorithm. Based on a pre-set threshold for output power, when the maximum threshold is exceeded, the control algorithm triggers an immediate emergency mode, outputting a maximum attenuation command of 90%. Simultaneously, the algorithm also analyzes and detects abnormal output power gradients. When the preset gradient threshold is exceeded, the control algorithm determines this as the start of a soliton explosion and activates a proportional adjustment mode, i.e., based on the excess amount... Calculate the attenuation coefficient Then, the driving voltage of the AOM driver is calculated, and the AOM driver controls the AOM to dynamically attenuate the laser power in order to suppress soliton explosion.

[0008] Furthermore, the logic for predicting soliton explosions in the real-time control algorithm of the data processing layer includes: Set a primary warning threshold and a secondary damage threshold. The primary warning threshold is 70% of the upper limit of the safe power in the cavity, and the secondary damage threshold is 90% of the damage power. Set an output power mutation gradient for monitoring. When the average power value is greater than the level 2 damage threshold, the emergency mode is activated, and the maximum attenuation of 90% is activated. When the average power value is between the first-level warning threshold and the second-level damage threshold, if the change in the power time gradient is greater than the output power sudden change gradient, the execution ratio will be reduced by 70%; otherwise, the execution ratio will be reduced by 50%. No adjustment is made when the average power value is less than the first-level warning threshold.

[0009] Furthermore, the specific control steps of the real-time control algorithm are as follows: Acquire the data output from the information acquisition layer and perform sampling and counting; Calculate the average power value: ,in The instantaneous power is calculated in real time for each sampling point; Read the average power value of the previous window from memory. Calculate the power time gradient ,in, This is the average power value from the previous window. For window spacing; when In case of emergency, activate emergency mode. ; when At that time, if Based on the prediction results, the linear relationship between the power overscalar and the attenuation intensity is constructed as follows: , like Based on the prediction results, the linear relationship between the power overscalar and the attenuation intensity is constructed as follows: , in, The maximum controllable power overshoot is set. Output power gradient; output attenuation coefficient command; when At that time, no adjustment is made.

[0010] Furthermore, the power control layer calculates the drive voltage based on the attenuation coefficient: , in, The voltage is half-wave voltage, determined by the acousto-optic coefficient of the crystal in the AOM.

[0011] Using the above method, multiple output power thresholds are set. When the highest threshold is exceeded, the control algorithm triggers an emergency mode, which calculates a maximum 90% attenuation command for the processing layer output. If the maximum threshold is not exceeded, a proportional adjustment protocol is triggered. The algorithm also analyzes and detects abnormal output power gradients. When the preset gradient threshold is exceeded, the control algorithm will determine that it is the starting position of soliton explosion and will start the proportional adjustment mode.

[0012] Furthermore, the power control layer drives the AOM to dynamically attenuate the transmitted light power according to the following formula: , in, This is due to the inherent insertion loss of AOM. The transmitted light power before attenuation. This represents the power of the transmitted light after attenuation.

[0013] Furthermore, the high-speed photodetector captures the laser power signal with a bandwidth of ≥1 GHz and outputs an analog voltage.

[0014] Furthermore, the signal acquisition layer digitizes the signal at a sampling rate of 500 MS / s to generate discrete sequence analog voltages, and then calculates the instantaneous power at each sampling point in real time. .

[0015] This application also includes a laser soliton explosion prediction and active suppression system based on real-time monitoring, which uses a laser soliton explosion prediction and active suppression method based on real-time monitoring, including... A high-speed photodetector acquires the output optical power of the laser in real time and converts the optical signal into an electrical signal; The laser power control system includes a signal acquisition layer, a data processing layer, and a power control layer. The signal acquisition layer receives the electrical signals output by the high-speed photodetector and converts the output analog electrical signals into digital signals through an analog-to-digital converter for acquisition. The data processing layer uses real-time control algorithms to calculate and analyze the collected data to obtain attenuation control commands; The power control layer uses a digital-to-analog converter to transmit the voltage value to the AOM driver according to the attenuation control command and the drive voltage. The AOM is dynamically adjusted by the radio frequency power to attenuate the pump output power before it is input to the laser.

[0016] This application also includes a processor for running a program, wherein the program executes a method for predicting and actively suppressing laser soliton explosions based on real-time monitoring.

[0017] This application also includes a computer-readable storage medium comprising a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform a method for predicting and actively suppressing laser soliton explosions based on real-time monitoring.

[0018] Compared with existing technologies, the advantages of this invention are: 1. Real-time power monitoring technology: By introducing a high-power photodetector (response bandwidth ≥1GHz), the laser output power can be monitored in real time, which can solve the problem of slow response speed, provide a basis for subsequent feedback control, and intervene in adjustment earlier than the traditional threshold response, avoiding the lag problem of "damage first and then control". 2. Laser power control system: It realizes threshold judgment and gradient prediction intervention, which can effectively suppress giant pulses, control the power level in the cavity, realize intelligent control to suppress solitons, and avoid the process of repeated manual adjustment. Attached Figure Description

[0019] Figure 1 This is an architecture diagram of the method in this application.

[0020] Figure 2 This is a flowchart of the laser power control system in the method of this application.

[0021] Figure 3 The logic diagram for soliton explosion prediction in the real-time control algorithm of this application is shown.

[0022] Figure 4 This is a flowchart illustrating the execution of the real-time control algorithm in the method described in this application.

[0023] Figure 5 This is a schematic diagram of a laser power control system according to a specific embodiment of this application.

[0024] Figure 6 This is a timing diagram of the soliton explosion suppression pulse during operation, which is a specific embodiment of this application. Detailed Implementation

[0025] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0026] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0027] Please see Figure 1-6 A method for predicting and actively suppressing laser soliton explosions based on real-time monitoring. Combination Figure 1 System architecture diagram and Figure 2 The system flowchart in this case shows that the core hardware components are a signal acquisition layer (ADC), a data processing layer (FPGA), and a power control layer (DAC), including the following steps: Signal acquisition and preprocessing: 20% of the output laser power signal is extracted by the optical beam splitter (splitting ratio 20:80). The high-speed photodetector receives the optical signal output by the laser, converts it into an electrical signal, and then converts the electrical signal into a digital signal through the ADC. The FPGA in the data processing layer performs calculations and processing on the digital signals from the ADC, based on... Figure 4 The real-time control algorithm execution flow shown determines and calculates the driving voltage value of the AOM driver. The digital-to-analog converter in the power control layer transmits the voltage value to the driver of the acousto-optic modulator, which in turn drives the AOM, achieving rapid attenuation of the input optical power through dynamic RF power regulation; Real-time control algorithm judgment conditions, refer to Figure 3 As shown, two thresholds are set: a primary warning threshold and a secondary damage threshold. The primary threshold is set as follows: The limit is 70% of the safe power limit within the cavity, and a secondary threshold is set ( The damage power is 90%, and a sudden output power gradient is set. Monitoring will be conducted.

[0028] The data processing module (FPGA) receives digital signals for calculation. Its control algorithm compares the digital signals with a set threshold. After the algorithm starts, the photodetector captures the laser power signal with a bandwidth of ≥1 GHz and outputs an analog voltage. The ADC digitizes the signal at a sampling rate of 500 MS / s, generating a discrete sequence of analog voltages, and then calculates the instantaneous power at each sampling point in real time. An accumulation register is set up within the FPGA to sum the instantaneous power of 1024 consecutive sampling points, thereby calculating the average power value for the current window. Furthermore, it reads the average power value from the previous window from the memory. Calculate the power time gradient ,in, This is the average power value from the previous window. The window interval is 2.048. ).

[0029] The FPGA executes the following judgment logic based on the hierarchical control algorithm: First, it detects... Does it exceed the second-degree damage threshold? If the threshold is exceeded, emergency mode will be triggered immediately, directly activating 90% of the maximum attenuation; if the threshold is not exceeded but is higher than the level 2 damage threshold, emergency mode will be triggered. Then, further analysis of the power gradient change is performed. When the gradient change exceeds a preset value... When this is determined to be a precursor to a soliton explosion, to avoid the resonant cavity losing lock due to the step response, a linear 70% attenuation is set. Based on the prediction results, a linear relationship between the power overscalar and the attenuation intensity is constructed, as shown in the following formula:

[0030] in, The maximum controllable power overshoot is set; the calculation layer transmits the attenuation coefficient to the DAC to generate the RF control voltage. ,in, The half-wave voltage is determined by the acousto-optic coefficient of the crystal in the AOM. The power control layer drives the AOM to dynamically attenuate the transmitted light power according to the following formula:

[0031] in, This is the inherent insertion loss of AOM. When the gradient change does not exceed a preset value... At that time, a linear 50% attenuation was set, and a linear relationship between the power overscalar and the attenuation intensity was constructed based on the prediction results: Furthermore, it initiates a "hot standby" pre-response, which increases the ADC sampling rate to 1 GS / s and presets the DAC voltage to 50% of the output half-wave voltage to the RF driver. This helps to shorten the AOM response time from 150ns to <50ns.

[0032] If none of the above conditions are triggered, the current state will be maintained.

[0033] This application also includes a laser soliton explosion prediction and active suppression system based on real-time monitoring, which uses a laser soliton explosion prediction and active suppression method based on real-time monitoring, including... A high-speed photodetector acquires the output optical power of the laser in real time and converts the optical signal into an electrical signal; The laser power control system includes a signal acquisition layer, a data processing layer, and a power control layer. The signal acquisition layer receives the electrical signals output by the high-speed photodetector and converts the output analog electrical signals into digital signals through an analog-to-digital converter for acquisition. The data processing layer uses real-time control algorithms to calculate and analyze the collected data to obtain attenuation control commands; The power control layer uses a digital-to-analog converter to transmit the voltage value to the AOM driver according to the attenuation control command and the drive voltage. The AOM is dynamically adjusted by the radio frequency power to attenuate the pump output power before it is input to the laser.

[0034] This application also includes a processor for running a program, wherein the program executes a method for predicting and actively suppressing laser soliton explosions based on real-time monitoring.

[0035] This application also includes a computer-readable storage medium comprising a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform a method for predicting and actively suppressing laser soliton explosions based on real-time monitoring.

[0036] In another specific embodiment, the system configuration diagram is referenced. Figure 1 and Figure 5 This implementation employs a ring-cavity erbium-doped fiber laser system, implementing explosion suppression during stable mode-locked operation. The fiber laser's internal structure consists of a laser diode generating a 976 nm continuous pump light, which is coupled to an EDF via a wavelength division multiplexer (WDM), generating a 1550 nm laser beam that propagates within the cavity. Subsequently, by using a polarization controller to compress the fiber to varying degrees, lasers with arbitrary polarization states can be generated. Combined with a polarization-dependent isolator, the transmittance of different wavelengths can be adjusted to achieve pulse narrowing. A 20:80 beam splitter (OC) serves as the output of the resonant cavity, outputting 20% ​​of the seed laser to a high-speed photodetector, from which an electrical signal is input to the laser power control system. The gain fiber EDF used within the resonant cavity has a group velocity dispersion of 61.2 fs² / mm, while the single-mode fiber has a group velocity dispersion of -21.8 fs² / mm. This example uses 1.3 meters of erbium-doped gain fiber, and by introducing a specific length of single-mode fiber, a near-zero dispersion cavity is constructed, resulting in near-zero net dispersion within the cavity. The pump optical power is input into the optical path of the laser cavity and inserted into an acousto-optic modulator (AOM). Based on the judgment result of the control system, a voltage control command is generated and input to the driver of the acousto-optic modulator through a digital-to-analog converter. The input optical power is rapidly attenuated through dynamic adjustment of radio frequency power, thereby achieving modulation of the power input into the laser cavity.

[0037] The data processing module (FPGA) receives digital signals for computation, and its control algorithm compares the quantized digital signals with the set judgment conditions. The algorithm employs the following security mechanisms, as set in this example: Level 1 threshold = 1.2 ; Secondary threshold = 1.5 ; Gradient threshold = 55 ; Experimental results refer to Figure 6 Instance timing analysis: Figure 6 (a) The time series at t=0.065 An anomalous power gradient appears, followed by a time interval of t=0.067. Giant pulse peak intensity 1.82 Emergency mode is triggered, 90% maximum attenuation is activated, and the output... The ADC then drives the AOM to perform a 90% decay, subsequently at t=0.082. The power within the control cavity is restored to a stable mold-locking state; Figure 6 (b) The time series at t=0.039 Abnormal power gradient changes began to appear and were detected. ( =55 (), and a peak intensity of approximately 1.35 was detected. Based on the linear decay triggered by the control algorithm, the superscalar value is first calculated. 0.15 Calculated based on the linear decay ratio: At 0.65, the computation layer transmits the attenuation coefficient to the DAC to generate the RF control voltage. The power control layer drives the AOM to dynamically attenuate the transmitted light power according to the following formula: This, in turn, drives the AOM, t=0.042-0.05 The pump input linearly increases the power of the optical cavity from 1.35. Decreased to 0.92 When t=0.05 It then enters a stable mold-locking state; Figure 6 (c) The reference group is a time series with stable mode-locking and a steady-state power of 0.76. (fluctuation 3%.

[0038] This embodiment demonstrates that, through a control algorithm that uses real-time threshold judgment and power gradient monitoring within the cavity, effective interception can be achieved in the early stages of soliton explosion development (energy accumulation stage), providing reliable protection for ultrafast lasers.

[0039] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A laser soliton explosion prediction and active suppression method based on real-time monitoring, characterized in that, The method comprises the following steps: Real-time acquisition of laser output optical power by high-speed photodetector, and conversion of optical signal into electrical signal; The electrical signal is transmitted to the laser power control system, which generates attenuation control instructions according to the judgment result and calculates the driving voltage; The voltage value is transmitted to the AOM driver through the digital-to-analog converter to drive the AOM to attenuate the transmitted light power; The laser power control system comprises a signal acquisition layer, a data processing layer and a power control layer, wherein the signal acquisition layer receives the electrical signal output by the high-speed photodetector, and converts the output analog electrical signal into a digital signal for acquisition through an analog-to-digital converter; the data processing layer calculates and analyzes the collected data using a real-time control algorithm to obtain attenuation control instructions; and the power control layer transmits the voltage value to the AOM driver using a digital-to-analog converter according to the attenuation control instructions and the driving voltage, and dynamically regulates the AOM through radio frequency power to attenuate the pump output power before inputting it into the laser.

2. The laser soliton explosion pre-judgment and active suppression method based on real-time monitoring according to claim 1, characterized in that, The logic of the real-time control algorithm in the data processing layer for predicting soliton explosion includes: Setting a first warning threshold and a second damage threshold, the first warning threshold being 70% of the upper limit of the intracavity safe power, and the second damage threshold being 90% of the damage power; and setting an output power mutation gradient for monitoring; When the average power value is greater than the second damage threshold, an emergency mode is started, and a 90% maximum attenuation is started; When the average power value is between the first warning threshold and the second damage threshold, if the change of the power time gradient is greater than the output power mutation gradient, a 70% attenuation is performed, otherwise a 50% attenuation is performed; When the average power value is less than the first warning threshold, no adjustment is made.

3. The laser soliton explosion pre-judgment and active suppression method based on real-time monitoring according to claim 2, characterized in that, The specific control steps of the real-time control algorithm are: Obtaining the data output by the information acquisition layer and performing sampling counting; The average power value is calculated: where The instantaneous power is calculated in real time for each sample point; reading the average power value of the previous window from memory calculating the power time gradient wherein is the average power value of the previous window, is the window interval; When Emergency mode is activated, ; When If , the linear relationship between the power excess and the attenuation intensity is constructed based on the prediction result as follows: ， If , the linear relationship between the power exceeding amount and the attenuation intensity is constructed based on the pre-judgment result as: ， wherein, is a maximum controllable power overshoot set, is an output power mutation gradient; an output decay coefficient instruction; When no adjustment is made.

4. The laser soliton explosion pre-judgment and active suppression method based on real-time monitoring according to claim 3, characterized in that, The power control layer calculates the driving voltage according to the attenuation coefficient: ， wherein, Vp is the half-wave voltage, determined by the acousto-optic coefficient of the crystal in the AOM.

5. The laser soliton explosion pre-judgment and active suppression method based on real-time monitoring according to claim 4, characterized in that, The power control layer drives the AOM to dynamically attenuate the transmitted light power according to the following formula: ， wherein, is the AOM intrinsic insertion loss, is the transmitted light power before attenuation, is the transmitted light power after attenuation.

6. The laser soliton explosion pre-judgment and active suppression method based on real-time monitoring according to claim 1, characterized in that, The high-speed photodetector captures the laser power signal with a bandwidth of ≥1 GHz and outputs an analog voltage.

7. The laser soliton explosion pre-judgment and active suppression method based on real-time monitoring according to claim 1, characterized in that, The signal acquisition layer is digitized at a sampling rate of 500 MS / s to generate a discrete sequence of analog voltages, and then the instantaneous power is calculated in real time for each sampling point .

8. A laser soliton explosion pre-judgment and active suppression system based on real-time monitoring, characterized in that, A laser soliton explosion prediction and active suppression method based on real-time monitoring is used, which comprises A high-speed photodetector for real-time acquisition of laser output optical power and conversion of optical signal into electrical signal; A laser power control system comprising a signal acquisition layer, a data processing layer and a power control layer; The signal acquisition layer receives the electrical signal output by the high-speed photodetector and converts the output analog electrical signal into a digital signal for acquisition through an analog-to-digital converter; The data processing layer calculates and analyzes the collected data using a real-time control algorithm to obtain attenuation control instructions; The power control layer transmits the voltage value to the AOM driver using a digital-to-analog converter according to the attenuation control instructions and the driving voltage, and dynamically regulates the AOM through radio frequency power to attenuate the pump output power before inputting it into the laser.

9. A processor, comprising: The processor is used to run a program, wherein the program runs to execute the laser soliton explosion prediction and active suppression method based on real-time monitoring of any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium comprises a stored program, wherein the computer readable storage medium controls the device where the computer readable storage medium is located to execute the method for predicting and actively suppressing laser soliton explosion based on real-time monitoring according to any one of claims 1-7 when the program is running.

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