Intelligent control method and device for high-power fiber femtosecond laser

Abstract

The invention provides an intelligent control method and device for a high-power optical fiber femtosecond laser, and belongs to the technical field of optical fiber femtosecond lasers. Comprising mode locking control and temperature control, specifically, the intelligent mode locking system is controlled to perform mode locking operation according to a feedback signal of the repetition frequency detection system, the intelligent temperature control system is controlled to perform graded temperature adjustment according to a feedback signal of the temperature sampling unit, and the intelligent temperature control system is controlled to adjust temperature setting to assist in mode relocking when mode locking fails. The high-power fiber femtosecond laser control system can adapt to complex external environment changes, and fast and effective control over the high-power fiber femtosecond laser is achieved.

Description

Technical Field

[0001] This invention belongs to the field of fiber femtosecond laser technology, and particularly relates to an intelligent control method and device for high-power fiber femtosecond lasers. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With the advancement of technology, femtosecond lasers are finding increasingly widespread applications in industrial processing, scientific research, and biomedicine. Compared to traditional solid-state lasers, fiber optics, as the gain medium, offer advantages such as superior heat dissipation, high environmental stability, excellent beam quality, and flexible output. Therefore, fiber-optic femtosecond lasers are receiving increasing attention.

[0004] High-power femtosecond fiber lasers combine the advantages of femtosecond lasers, which have a very small heat-affected zone, and fiber lasers, which use rare-earth-doped optical fibers as the gain medium and are excited by pumping. By taking advantage of the inherent advantages of the fiber platform, they can achieve femtosecond pulse output with high average power and high pulse energy.

[0005] As the output optical power of fiber femtosecond lasers increases, the challenges faced in developing high-power femtosecond fiber lasers become increasingly complex. These challenges primarily include nonlinear effects, thermal management and mode instability, dispersion and dispersion management, gain narrowing and spectral management. Consequently, researchers in the field have proposed various methods to address these issues; however, these methods generally suffer from the following technical shortcomings: For temperature control methods based on TEC modules, most existing technologies employ PID control algorithms. However, PID control loops require adjusting multiple control parameters, and parameter tuning is highly complex, relying heavily on human experience. Since everyone's experience differs, this leads to poor tuning results for the PID control loop parameters, and the debugging process is time-consuming and labor-intensive. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides an intelligent control method and device for high-power fiber femtosecond lasers, which can adapt to complex external environmental changes and achieve rapid and effective control of high-power fiber femtosecond lasers.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: The first aspect of this invention provides an intelligent control method for high-power fiber femtosecond lasers.

[0008] A smart control method for high-power fiber femtosecond lasers includes: mode-locking control and temperature control; The mode-lock control includes: initializing and configuring the control parameters of the fiber femtosecond laser; acquiring the repetition frequency signal of the optical resonant cavity in real time through the repetition frequency detection system, and dynamically adjusting the pump drive current of the execution unit through the control unit based on the feedback from the repetition frequency detection system, so as to realize the mode-lock control of the optical resonant cavity; The temperature control includes: based on multi-level temperature sampling feedback, adjusting the cooling execution unit in stages through the control unit to achieve temperature control of key parts of the fiber femtosecond laser; The mold-locking control and temperature control work together. If mold-locking fails during the mold-locking control process, the temperature control is triggered to adjust the temperature setpoint to assist in re-molding.

[0009] Furthermore, the control parameters used for the initialization configuration include: the sampling time interval of the signal conversion unit in the fiber femtosecond laser, the target repetition rate range, and the pump drive current threshold.

[0010] Furthermore, the implementation of the mode-locking control includes: comparing the acquired repetition frequency signal with a preset repetition frequency target range, and adjusting the pump drive current according to a preset strategy until the repetition frequency signal falls into the repetition frequency target range and remains stable, so as to achieve mode-locking.

[0011] Furthermore, the pump drive current is adjusted according to a preset strategy, including: If the repetition frequency signal falls within the repetition frequency target range, the pump drive current is increased by a preset first gradient until it jumps out of the repetition frequency target range, and the first current value is recorded; then the pump drive current is decreased by the first gradient until it jumps out of the repetition frequency target range again, and the second current value is recorded.

[0012] Furthermore, adjusting the pump drive current according to the preset strategy also includes: if the repetition frequency signal does not fall within the repetition frequency target range and is unstable, then after adjusting the pump drive current to a preset threshold current, the temperature setting value is adjusted within the preset temperature adjustment range by triggering temperature control, and the repetition frequency signal is reacquired.

[0013] Furthermore, the temperature control includes a temperature control strategy and a fan control strategy.

[0014] Furthermore, the temperature control strategy is divided into three levels of temperature control and graded adjustment based on the different temperature sensitivities of each key component in the fiber femtosecond laser; the fan control strategy adjusts the fan speed according to the difference between the ambient temperature and the target temperature to cooperate with the cooling execution unit for heat exchange; wherein, the fan speed is steplessly regulated by a pulse width modulation signal.

[0015] Furthermore, the cooling execution unit implements graded regulation based on a semiconductor cooler, specifically: for each temperature control level, the real-time temperature of the corresponding area is independently collected; the real-time temperature is compared with the target temperature range of the corresponding temperature control level; based on the comparison result, the duty cycle of the PWM signal applied to the corresponding semiconductor cooler at that temperature control level is dynamically adjusted to achieve graded progressive temperature control.

[0016] A second aspect of the present invention provides an intelligent control device for a high-power fiber femtosecond laser.

[0017] A smart control device for a high-power fiber femtosecond laser, comprising: Control system, intelligent mold-locking system, high repetition rate detection system and intelligent temperature control system; The control system includes a main control module, a storage module, and a clock module; The intelligent locking system is communicatively connected to the control system and is used for locking the repetition frequency; The frequency repetition detection system is communicatively connected to the control system and the intelligent mode-locking system, and is used to detect the frequency repetition of the optical resonant cavity in real time and provide a feedback signal to the main control module. The intelligent temperature control system is communicatively connected to the control system and includes a multi-stage refrigeration actuator and an axial fan. The main control module is configured to: control the intelligent mold-locking system to perform mold-locking operation based on the feedback signal of the repetition rate detection system, control the intelligent temperature control system to perform graded temperature adjustment based on the feedback signal of the temperature sampling unit, and control the intelligent temperature control system to adjust the temperature setting to assist in re-molding when mold-locking fails.

[0018] Furthermore, the multi-stage refrigeration execution unit includes: The first-stage temperature control unit has its cooling execution unit mounted on the overall substrate of the fiber femtosecond laser. The second-stage temperature control unit has its cooling execution unit located in the optical magnification cavity; The third-stage temperature control unit has its refrigeration execution unit located in the amplification stage multimode pump; Each temperature control unit is equipped with a temperature sampling unit to form an independent closed-loop control circuit.

[0019] The above one or more technical solutions have the following beneficial effects: This invention provides a novel method for mode-locking and temperature control of high-power fiber femtosecond lasers. Specifically, it controls an intelligent mode-locking system to perform mode-locking operations based on feedback signals from a repetition rate detection system, and controls an intelligent temperature control system to perform graded temperature adjustments based on feedback signals from a temperature sampling unit. Furthermore, in the event of mode-locking failure, the intelligent temperature control system adjusts the temperature setting to assist in re-mode-locking. Thus, temperature control achieves graded adjustment based on multi-level temperature sampling feedback, working synergistically with mode-locking control. This invention reduces the complexity of tuning various control parameters, and the control process is automated. Compared to existing technologies, it can adapt to complex external environmental changes, achieving faster and more effective control of high-power fiber femtosecond lasers.

[0020] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a flowchart of an intelligent control method for a high-power fiber femtosecond laser according to Embodiment 1 of the present invention.

[0023] Figure 2 This is a schematic diagram of the functional relationships of components in the multi-level temperature sampling feedback process in Embodiment 1 of the present invention.

[0024] Figure 3 This is a schematic diagram of the temperature control relationships at each level in Embodiment 1 of the present invention.

[0025] Figure 4 This is a structural diagram of an intelligent control device for a high-power fiber femtosecond laser according to Embodiment 2 of the present invention. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0028] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0029] Example 1 This embodiment discloses an intelligent control method for high-power fiber femtosecond lasers.

[0030] like Figure 1 As shown, an intelligent control method for a high-power fiber femtosecond laser includes: mode-locking control and temperature control; The mode-lock control includes: initializing and configuring the control parameters of the fiber femtosecond laser; acquiring the repetition frequency signal of the optical resonant cavity in real time through the repetition frequency detection system, and dynamically adjusting the pump drive current of the execution unit through the control unit based on the feedback from the repetition frequency detection system, so as to realize the mode-lock control of the optical resonant cavity; The temperature control includes: based on multi-level temperature sampling feedback, adjusting the cooling execution unit in stages through the control unit to achieve temperature control of key parts of the fiber femtosecond laser; The mold-locking control and temperature control work together. If mold-locking fails during the mold-locking control process, the temperature control is triggered to adjust the temperature setpoint to assist in re-molding.

[0031] Based on the above process, this invention can adapt to complex changes in the external environment and achieve rapid and effective control of high-power fiber femtosecond lasers. To facilitate understanding of the technical solution of this invention, the specific implementation methods of this invention will be further explained and described below.

[0032] This invention provides an intelligent control method for high-power fiber femtosecond lasers. It establishes a multi-level sampling feedback adjustment mechanism from input to output through an intelligent mode-locking system and a repetition rate detection system. The intelligent mode-locking system and repetition rate detection system for implementing this mechanism consist of a repetition rate sampling unit, a signal amplification unit, a signal conversion unit, a control unit, and an execution unit. In this embodiment, an equivalent light source for one resonant cavity is derived from the optical resonant cavity. An external photodiode serves as the repetition rate sampling unit, an external chip positioned above the circuit board serves as the signal amplification and signal conversion unit, a main control module serves as the control unit, and a single-mode pump serves as the execution unit. The relationships between the components are as follows: Figure 2 As shown. The function of the execution unit is to precisely control the current of the single-mode pump; by controlling the magnitude of the single-mode pump current and the temperature control parameters, the optical system of the resonant cavity can be controlled; and by controlling the optical system of the resonant cavity, frequency repetition rate locking and intelligent mode locking can be achieved.

[0033] As a specific implementation method, the implementation of mode-locked control includes: Step 1-1: Initialize and configure the control parameters of the fiber femtosecond laser.

[0034] The sampling time interval of the control unit to the signal conversion unit is set to 1 second, the target range of the repetition frequency is set to f1-f2, and the pump drive current threshold I is set; where f1 represents the lower limit of the target range of the repetition frequency and f2 represents the upper limit of the target range of the repetition frequency.

[0035] Step 1-2: The repetition frequency signal of the optical resonant cavity is acquired in real time through the repetition frequency detection system and denoted as f3.

[0036] Steps 1-3: Based on feedback from the repetition rate detection system, the pump drive current of the execution unit is dynamically adjusted by the control unit to achieve mode-lock control of the optical resonant cavity. Specifically, this can be achieved through the following methods: Step 1-3-1: Obtain the current pump current value I1.

[0037] Step 1-3-2: Calculate whether the repetition frequency f3 falls within the interval f1-f2. Simultaneously, perform equal-interval sampling every 1 second, accumulating 3 samplings. If it falls within the range, increase the pump drive current in units of 1mA and record it as I1. Each time the pump current value is changed, perform real-time sampling of the repetition frequency until the repetition frequency f3 value jumps out of the f1-f2 range. Record the pump drive current Imax at this moment and proceed to step 1-3-3. If it is not within the range, proceed to step 1-3-4.

[0038] Step 1-3-3: Reduce the pump drive current I1 in 1mA increments. Each time the pump current value is changed, perform real-time sampling of the repetition frequency until the repetition frequency F3 value jumps out of the f1-f2 range. Record the pump drive current at this moment and denote it as Imin.

[0039] Step 1-3-4: Determine if the repetition frequency f3 is stable. If it is stable, drive the pump drive current to the current threshold I, and reduce the pump drive current according to the gradient of 5mA pump drive current change until the repetition frequency falls into the range of f1-f2, and execute step 1-3-2. If the repetition frequency is unstable, go to step 1-3-5.

[0040] Step 1-3-5: Drive the pump current to the current threshold I, adjust the three-stage temperature control platform and set the temperature range T1; within the range of T1±10℃, perform temperature control according to a 1℃ gradient, sample at equal intervals of 1s, and collect the repetition frequency f3 by accumulating 3 samples until the repetition frequency falls into the range of f1-f2, and then execute step 1-3-2; otherwise, go to step 1-3-6.

[0041] Steps 1-3-6: Synchronize the current pump drive current value, temperature control target value, repetition rate value, and other information to the host computer software. If an alarm indicates mold locking failure for 3 seconds, shut down the pump drive power supply while maintaining serial communication.

[0042] Based on the above mode-locking method, intelligent control of mode-locking can be achieved during the construction of the resonant cavity. This intelligent mode-locking method can achieve intelligent mode-locking, especially during long-term stable operation, overcoming the problem of loss of mode-locking after long-term operation of fiber femtosecond lasers in the prior art.

[0043] As a specific implementation method, temperature control includes: The intelligent temperature control system consists of a semiconductor cooler (TEC) and a fan, forming a two-stage dynamic temperature control device. The fan employs a stepless speed regulation strategy and uses PWM control for real-time dynamic adjustment based on the overall temperature control strategy. Its main purpose is to cooperate with the TEC temperature control strategy to exchange heat step-by-step. The TEC employs a three-stage temperature control strategy. The temperature control device is divided into three stages according to temperature control accuracy. The entire temperature control device and equipment are placed on an aluminum alloy substrate. The first stage, being the coarsest, is used for temperature control; the second stage, due to the high temperature sensitivity of the optical amplification cavity, is used; and the third stage, due to the highest temperature requirements of the multi-mode pump in the amplification stage, is used. Each stage of temperature control is equipped with a real-time temperature sampling and detection closed-loop system to provide samples for the temperature control strategy. The relationship between the temperature control stages is as follows: Figure 3 As shown.

[0044] The purpose of the intelligent temperature control system is to ensure the stable operation of all functional modules of the fiber femtosecond laser, in order to cope with the impact of environmental temperature changes on various performance indicators during long-term stability and long-cycle testing. Its core objectives are fast dynamic response, good environmental adaptability, and high stability. In this embodiment, the target temperature needs to be stabilized within a preset temperature threshold T_set. The three-stage temperature control device operates in different temperature ranges, gradually approaching the target value according to a control strategy from coarse to fine adjustment.

[0045] Level 1 control, belonging to coarse and basic temperature control, is used to cope with large temperature deviations, achieving rapid heating and cooling, and quickly bringing the temperature close to the target range. This level of control is characterized by high power and fast response, but low accuracy and a tendency to overshoot.

[0046] Secondary regulation, belonging to intermediate and balanced temperature control, means that, based on primary regulation, it eliminates fluctuations within a moderate range and further stabilizes the temperature to suppress overshoot. Compared to primary regulation, this level of regulation has more balanced control parameters and is responsible for stabilizing the main stage.

[0047] The three-level control system, which involves fine-tuning and micro-adjustment, is used to eliminate high-frequency, minute temperature fluctuations and noise, ultimately achieving "ultra-stable" performance.

[0048] Specifically, the intelligent temperature control method for fiber femtosecond lasers is as follows: Step 2-1: Set the third-level temperature control index T3, the second-level temperature control index T2, and the first-level temperature control index T1.

[0049] Step 2-2: Obtain the real-time temperature values t1, t2, and t3 of the third-level platform, as well as the current ambient temperature value t; where t1, t2, and t3 respectively represent the real-time temperature values of the T1 platform, T2 platform, and T3 platform.

[0050] Step 2-3: Determine the initial rotational speed value v of the fan according to the current ambient temperature value t (note that if the t value is less than the target temperature value T_set, the fan does not work).

[0051] Step 2-4: Determine the working mode by comparing with the real-time temperature value.

[0052] If t1 > T1, TEC refrigeration. In the specific implementation process, the t1 value is monitored in real time, sampled once per second, and the temperature difference before and after is compared. If the difference is less than 0.5°, the PWM regulation intensity is increased at a 10% step speed. After each change in the PWM step speed, three samplings are required before continuing to adjust the strategy. When the PWM regulation of TEC reaches 60%, compare the temperature sampling differences between the previous and the current times. If the difference is less than 0.5°, the PWM adjustment step speed is reduced from 10% to 5%; at the same time, the fan speed is adjusted according to the 5% step speed regulation strategy for rapid heat transfer. When the fan reaches 80% speed, the upper computer triggers a high-temperature alarm signal for 3 seconds, and the power-off protection device is activated.

[0053] If t1 < T1, TEC heating. At this time, the fan does not start, and the regulation strategy is the same as above. When the real-time sampled temperature t1 falls within the T1 index range, go to Step 2-5.

[0054] Step 2-5: The secondary regulation does not require the same high speed as the primary regulation nor the same high precision as the tertiary regulation. It is a transition platform.

[0055] If t2 > T2, TEC refrigeration. In the specific implementation process, the t2 value is detected in real time, sampled once every 0.5 seconds, and the difference before and after is compared. If the difference is less than 0.1°C, the PWM regulation intensity is increased at a 5% step speed. After each change in the PWM step speed, three samplings are required before continuing to adjust the strategy; when the real-time sampled temperature t2 falls within the T2 index range, go to Step 2-6. After the PWM step speed reaches 80%, if the real-time sampled temperature t2 has not fallen within the T2 index, go to Step 2-7.

[0056] If t2 < T2, TEC heating, and the regulation strategy is the same as above.

[0057] Step 2-6: The third-level temperature control is the last level of platform to ensure the final temperature stability. Compared with the regulation speeds of the previous two levels, it more pursues the stability of the real-time temperature and the ability to resist disturbance and prevent overshoot.

[0058] In the specific implementation process, the temperature feedback data of t3 is sampled in real time at 0.1s intervals. If the difference is less than 0.05℃, the PWM control intensity is increased by 1% step speed. Each time the PWM step speed is changed, five samples must be waited before the strategy can be adjusted again. When the temperature falls within ±0.01 of the T3 index range, the PWM control step speed is changed to 0.1%, and after 10 samples, the step speed strategy is adjusted by calculating the average value.

[0059] Step 2-7: Sample the temperature t1 in real time and detect the PWM speed control range. Adjust the T1 index according to the ±3℃ index, with an adjustment granularity of 0.5℃, and perform synchronous temperature control on the level 2 platform in real time according to Step 2-5 until the temperature t2 value falls into the T2 range; if the temperature t2 value still cannot fall into the T2 range after the T1 index is adjusted to the ±3℃ index, then proceed to Step 2-8.

[0060] Step 2-8: Sample the t2 temperature value in real time, detect the PWM control speed, and sample at 0.5S intervals. Accumulate 10 samples and determine if the t2 value falls within the T2±1℃ range. If it does, adjust the T2 index according to the ±1℃ index, with an adjustment granularity of 0.1℃. Perform real-time synchronous temperature control on the 3-level platform as per Step 2-6 until the t3 temperature value falls within the T3 range. If the t3 temperature value still cannot fall within the T3 range after adjusting the T2 index to the ±1℃ index, proceed to Step 2-9; if it does not fall within the T2±1℃ range, proceed to Step 2-9. Steps 2-9: Real-time display of fan speed, PWM step speed and duty cycle of the three-level temperature control platform, ambient temperature, and other information via the host computer. When a high-temperature alarm occurs, the indicator light flashes continuously for 10 seconds. After 10 seconds, all power supplies related to the temperature control are cut off, leaving only the communication interface operational.

[0061] Based on the methods provided by this invention, the following technological breakthroughs can be achieved compared to existing technologies: 1) The fiber femtosecond laser adopts a novel architecture and intelligent strategy, enabling it to adapt to complex external environmental changes and possessing significant characteristics such as fast convergence speed, timely dynamic response, and wide temperature control range. Simultaneously, the temperature control strategy provides the fiber femtosecond laser with more stable performance indicators and high reliability and stability, typical of industrial-grade performance. 2) This invention provides detailed explanations of the threshold settings, specific strategies, and underlying principles during dynamic mode-locking and temperature control, and the implementation process is simple, avoiding instability caused by human interference during use. Accordingly, precise control of the intelligent operation of the fiber femtosecond laser can be achieved, enabling it to operate stably under stable conditions for extended periods, thereby improving the performance and stability of the fiber femtosecond laser.

[0062] Example 2 This embodiment discloses an intelligent control device for a high-power fiber femtosecond laser.

[0063] like Figure 4 As shown, an intelligent control device for a high-power fiber femtosecond laser includes: a control system, an intelligent mode-locking system, a repetition rate detection system, and an intelligent temperature control system. The control system includes a main control module, a storage module, and a clock module; The intelligent locking system is communicatively connected to the control system and is used for locking the repetition frequency; The frequency repetition detection system is communicatively connected to the control system and the intelligent mode-locking system, and is used to detect the frequency repetition of the optical resonant cavity in real time and provide a feedback signal to the main control module. The intelligent temperature control system is communicatively connected to the control system and includes a multi-stage refrigeration actuator and an axial fan. The main control module is configured to: control the intelligent mold-locking system to perform mold-locking operation based on the feedback signal of the repetition rate detection system, control the intelligent temperature control system to perform graded temperature adjustment based on the feedback signal of the temperature sampling unit, and control the intelligent temperature control system to adjust the temperature setting to assist in re-molding when mold-locking fails.

[0064] Furthermore, the multi-stage refrigeration execution unit includes: The first-stage temperature control unit has its cooling execution unit mounted on the overall substrate of the fiber femtosecond laser. The second-stage temperature control unit has its cooling execution unit located in the optical magnification cavity; The third-stage temperature control unit has its refrigeration execution unit located in the amplification stage multimode pump; Each temperature control unit is equipped with a temperature sampling unit to form an independent closed-loop control circuit.

[0065] Furthermore, the control system includes: a main control module, a storage module, and a clock module. The main control module is responsible for real-time interaction and communication with each submodule; the storage module stores system programs, important parameters, instructions, and operational data; and the clock module provides a reference clock source for the main control module.

[0066] Furthermore, an intelligent control device for a high-power fiber femtosecond laser also includes a power supply and communication system consisting of an electronic system and a communication subsystem. The power supply system primarily provides power to the fiber femtosecond laser. Since the power supply range for fiber femtosecond lasers is quite broad, the stability of the power supply system is crucial. Specifically, the power supply system is mainly used to provide different power levels to various systems to ensure reliable loads, low ripple noise, high response, and high stability.

[0067] The communication subsystem primarily serves as a medium and pathway for communication between the fiber femtosecond laser's main control system and the host computer, as well as for communication with external devices. It mainly comprises a USB communication unit, a pulse output unit, and a signal indication unit. The USB communication unit provides a connection between the main control system and the host computer; the pulse output unit provides a communication pathway between the main control system and external devices; and the signal indication unit provides alarms, information output, and status indications for the user.

[0068] Furthermore, the importance of the intelligent temperature control system lies primarily in its ability to accurately and rapidly meet temperature control requirements in real time based on environmental changes, thereby laying the foundation for the long-term stable operation of fiber femtosecond lasers and their applicability to various working conditions. The core of intelligent temperature control is the dynamic adjustment closed-loop strategy of the main control unit. This strategy addresses the problems of low adjustment accuracy and slow convergence speed found in previous products by implementing system-level improvements. The effects achieved by this intelligent temperature control system are as follows: 1) Temperature control precision is achieved to an extremely fine granularity, enabling the fiber femtosecond laser to operate within a range of ±0.1℃; 2) Temperature control dynamic response range is large, enabling the fiber femtosecond laser to operate within an ambient temperature range of ±20℃ / min; 3) Response time is short, and the waiting time can be controlled within 3 minutes for different application scenarios of the fiber femtosecond laser; 4) Temperature control range is wide, covering application scenarios from 0℃ to 40℃.

[0069] Furthermore, the intelligent mode-locking system is primarily used to achieve frequency repetition rate (FR) locking. Within a reproducible optical resonant cavity, FR locking is influenced by many factors, but the input current of the single-mode pump, as the source of the resonant cavity, is the most crucial variable. The intelligent mode-locking system uses the detection results of the FR detection system as the criterion for FR locking, dynamically and in real-time adjusting the single-mode pump current value of the resonant cavity input stage. Through intelligent tuning strategies, it achieves rapid mode-locking and rapid locking after loss of lock at high and low temperatures.

[0070] Furthermore, the stability of the fiber femtosecond laser resonator is the most fundamental factor affecting the overall system stability. Therefore, a repetition rate (RPR) detection system is needed to collect RPR signals for reliability verification and to determine whether the resonator is operating well. The entire RPR detection system mainly consists of a photodetector, a differential amplifier circuit, a differential-to-single-ended converter circuit, and an FPGA control system, used to achieve real-time RPR detection.

[0071] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A smart control method for high-power fiber femtosecond lasers, characterized in that, This includes mold-locking control and temperature control; The mode-lock control includes: initializing and configuring the control parameters of the fiber femtosecond laser; acquiring the repetition frequency signal of the optical resonant cavity in real time through the repetition frequency detection system, and dynamically adjusting the pump drive current of the execution unit through the control unit based on the feedback from the repetition frequency detection system, so as to realize the mode-lock control of the optical resonant cavity; The temperature control includes: based on multi-level temperature sampling feedback, adjusting the cooling execution unit in stages through the control unit to achieve temperature control of key parts of the fiber femtosecond laser; The mold-locking control and temperature control work together. If mold-locking fails during the mold-locking control process, the temperature control is triggered to adjust the temperature setpoint to assist in re-molding.

2. The intelligent control method for a high-power fiber femtosecond laser as described in claim 1, characterized in that, The control parameters used for the initialization configuration include: the sampling time interval of the signal conversion unit in the fiber femtosecond laser, the target repetition rate range, and the pump drive current threshold.

3. The intelligent control method for a high-power fiber femtosecond laser as described in any one of claims 1-2, characterized in that, The mode-locking control is implemented by comparing the acquired repetition frequency signal with a preset repetition frequency target range, and adjusting the pump drive current according to a preset strategy until the repetition frequency signal falls into the repetition frequency target range and remains stable, so as to achieve mode-locking.

4. The intelligent control method for a high-power fiber femtosecond laser as described in claim 3, characterized in that, Adjust the pump drive current according to a preset strategy, including: If the repetition frequency signal falls within the repetition frequency target range, the pump drive current is increased by a preset first gradient until it jumps out of the repetition frequency target range, and the first current value is recorded; then the pump drive current is decreased by the first gradient until it jumps out of the repetition frequency target range again, and the second current value is recorded.

5. The intelligent control method for a high-power fiber femtosecond laser as described in claim 3, characterized in that, Adjusting the pump drive current according to the preset strategy also includes: if the repetition frequency signal does not fall into the repetition frequency target range and is unstable, then after adjusting the pump drive current to a preset threshold current, the temperature setting value is adjusted within the preset temperature adjustment range by triggering temperature control, and the repetition frequency signal is reacquired.

6. The intelligent control method for a high-power fiber femtosecond laser as described in claim 1, characterized in that, The temperature control includes a temperature control strategy and a fan control strategy.

7. The intelligent control method for a high-power fiber femtosecond laser as described in claim 6, characterized in that, include: The temperature control strategy is divided into three levels and adjusted in stages according to the different temperature sensitivities of each key component in the fiber femtosecond laser. The fan control strategy adjusts the fan speed based on the difference between the ambient temperature and the target temperature to cooperate with the cooling execution unit for heat exchange; wherein, the fan speed is steplessly regulated by a pulse width modulation signal.

8. The intelligent control method for a high-power fiber femtosecond laser as described in claim 7, characterized in that, The cooling execution unit implements graded regulation based on a semiconductor cooler. Specifically, for each temperature control level, the real-time temperature of the corresponding area is independently collected; the real-time temperature is compared with the target temperature range of the corresponding temperature control level; and based on the comparison result, the duty cycle of the PWM signal applied to the corresponding semiconductor cooler at that temperature control level is dynamically adjusted to achieve graded progressive temperature control.

9. An intelligent control device for a high-power fiber femtosecond laser, characterized in that, This includes a control system, an intelligent mold-locking system, a repetition rate detection system, and an intelligent temperature control system; The control system includes a main control module, a storage module, and a clock module; The intelligent locking system is communicatively connected to the control system and is used for locking the repetition frequency; The frequency repetition detection system is communicatively connected to the control system and the intelligent mode-locking system, and is used to detect the frequency repetition of the optical resonant cavity in real time and provide a feedback signal to the main control module. The intelligent temperature control system is communicatively connected to the control system and includes a multi-stage refrigeration actuator and an axial fan. The main control module is configured to: control the intelligent mold-locking system to perform mold-locking operation based on the feedback signal of the repetition rate detection system, control the intelligent temperature control system to perform graded temperature adjustment based on the feedback signal of the temperature sampling unit, and control the intelligent temperature control system to adjust the temperature setting to assist in re-molding when mold-locking fails.

10. The intelligent control device for a high-power fiber femtosecond laser as described in claim 9, characterized in that, The multi-stage refrigeration execution unit includes: The first-stage temperature control unit has its cooling execution unit mounted on the overall substrate of the fiber femtosecond laser. The second-stage temperature control unit has its cooling execution unit located in the optical magnification cavity; The third-stage temperature control unit has its refrigeration execution unit located in the amplification stage multimode pump; Each temperature control unit is equipped with a temperature sampling unit to form an independent closed-loop control circuit.

Images