Parameter intelligent detection device and method for femtosecond laser

Abstract

This invention discloses an intelligent parameter detection device and method for femtosecond lasers. It utilizes the detection light output from the optical path splitter for real-time repetition rate detection, intelligently adjusting the laser's pump power and the temperature of the semiconductor saturable absorber (SAM) to ensure stable SAM operation in saturation. It automatically detects the laser's start-up current and operating current range, sets the optimal start-up and operating current parameters through an algorithm, and saves the parameters in the internal memory, completing the electrical control parameter tuning process for the laser. The entire parameter tuning process does not require additional external instruments, greatly simplifying the operation process, improving work efficiency, reducing production costs, and protecting human safety.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, specifically relating to an intelligent parameter detection device and method for femtosecond lasers. Technical Background

[0002] Based on the design and manufacturing documents, the various components of the laser, including optical lenses, optical fibers, and laser crystals, are fabricated and assembled to form a complete femtosecond laser optical path system. The laser is then debugged, including adjusting the optical path, calibrating the focal length, and optimizing laser pulse parameters, to ensure that the laser can generate high-quality femtosecond laser pulses.

[0003] The adjustment of electrical control parameters for femtosecond lasers is a complex and delicate process, involving the optimization and balancing of multiple parameters to ensure laser performance and stability. Currently, in the industry, the method for adjusting electrical control parameters during the assembly and debugging of femtosecond lasers typically involves optical engineers manually operating the laser drive current, measuring the attenuated output spectrum using a spectrometer, and observing the output pulse waveform with an oscilloscope to determine if mode-locking was successful. Human error can cause the current to exceed the maximum pump current, or accidental insertion or removal while the laser is powered on can damage the pump. Furthermore, during testing, it may be necessary to plug and unplug fibers to switch power or the spectrometer; if the laser accidentally enters the eyes, it can cause irreversible damage.

[0004] In femtosecond laser technology, the main method for obtaining ultrashort pulses is mode-locking. Mode-locking methods are generally divided into active mode-locking and passive mode-locking, with the most common method currently being mode-locking through the saturable absorption effect. The parameters of a saturable absorber depend on the thermal expansion of the absorbing material and the semiconductor band gap, which are highly susceptible to the influence of the external ambient temperature. Therefore, this invention provides an intelligent parameter detection device and method for femtosecond lasers, determining the suitable temperature and operating current under frequency-locked conditions, and ensuring successful mode-locking of the laser under these suitable conditions. Summary of the Invention

[0005] The purpose of this invention is to provide an intelligent parameter detection device and method for femtosecond lasers. It utilizes the detection light output from the optical path splitter for real-time repetition rate detection, intelligently adjusts the laser's pump power and the temperature of the semiconductor saturable absorber (SAM) to ensure stable SAM operation in saturation, automatically detects the laser's start-up current and operating current range, sets the optimal start-up current and operating current parameters through an algorithm, and writes the parameters into the internal memory for storage, thus completing the electrical control parameter tuning process of the laser. The entire parameter tuning process does not require additional external instruments, greatly simplifying the operation process, improving work efficiency, reducing production costs, and protecting human safety.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] A femtosecond laser parameter intelligent detection device includes an LD pump source, a TWDM wavelength division multiplexer, a SAM semiconductor saturable absorber, a DAC digital-to-analog converter chip, a PD photodetector, a TEC thermoelectric cooler, a temperature sensor, a motor, an FPGA controller, and a parameter memory. The LD pump source generates the laser beam. The LD pump source is connected to the input of the TWDM. The output of the TWDM is connected to both the SAM semiconductor saturable absorber and the PD photodetector. The TWDM splits the laser beam into two paths: one path is sent to the SAM semiconductor saturable absorber, and the other path is sent to the PD photodetector to convert the input optical signal into a detectable pulse. The device is connected to the FPGA controller to send detectable pulses to the FPGA controller and determine the repetition frequency of the detectable pulses; the temperature sensor is used to collect the temperature of the SAM semiconductor saturable absorber in real time, and is connected to the FPGA controller to send the collected temperature to the FPGA controller; the TEC thermoelectric cooler is connected to the FPGA controller and cools the SAM semiconductor saturable absorber based on the control commands sent by the FPGA controller; the motor is connected to the FPGA controller and changes the position of the semiconductor saturable absorber under the control of the FPGA controller; the DAC digital-to-analog chip is connected to the FPGA controller and inputs LD current to the LD pump source under the control of the FPGA controller.

[0008] A method for intelligent parameter detection of a femtosecond laser includes the following steps:

[0009] Step 1: Input the current optical path configuration temperature range Tmin~Tmax, SAM damage threshold Imin~Imax, and repetition rate range Fmin~Fmax through the host computer interface. After clicking "Start Detection", the information is sent to the FPGA controller to execute Step 2.

[0010] Step 2: The FPGA controller controls the TEC thermoelectric cooler to operate at a temperature of Tmin. The TEC thermoelectric cooler cools the SAM semiconductor saturable absorber. Step 3 is then executed.

[0011] Step 3: Monitor the temperature of the SAM semiconductor saturable absorber in real time using a temperature sensor. If the temperature reaches the range of Tmin ~ (Tmin+1)℃, proceed to step 4; otherwise, proceed to step 3.

[0012] Step 4: The FPGA controller controls the DAC digital-to-analog chip to control the LD input current to Imin, which is sent to the LD pump source. The LD pump source generates pump light. The TWDM wavelength division multiplexer splits the pump light into a first pump light and a second pump light. The first pump light enters the SAM semiconductor saturable absorber and generates a femtosecond laser pulse. The second pump light enters the PD photodetector and executes step 5.

[0013] Step 5: The second pump light is converted into a detectable pulse by the PD photodetector and sent to the FPGA controller to detect whether the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 6; otherwise, proceed to step 14.

[0014] Step 6: Record the current temperature of the TEC thermoelectric cooler as T, the current operating current of the LD pump source as IL, and then proceed to step 7;

[0015] Step 7: The FPGA controller determines whether the current operating current of the LD pump source exceeds Imax. If it does, proceed to step 8; otherwise, proceed to step 12.

[0016] Step 8: The FPGA controller controls the LD input current generated by the DAC digital-to-analog chip to be Imax, and then executes step 9;

[0017] Step 9: Convert the pulse into a detectable pulse using a PD photodetector and send it to the FPGA controller to check if the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 10; otherwise, proceed to step 11.

[0018] Step 10: Record the current temperature of the TEC thermoelectric cooler as Ts, the current operating current of the LD pump source as IM, calculate Is=(IL+IM) / 2, save the result to the parameter memory, and end the detection; the stored parameters are the inherent parameters of the product and can be used directly when the product is turned on next time to ensure normal laser operation.

[0019] Step 11: Record the current temperature of the TEC thermoelectric cooler as Ts, the previously configured pump current value as IM, calculate Is=(IL+IM) / 2, save the result to the parameter memory, and end the detection;

[0020] Step 12: The FPGA controller controls the pump input current generated by the DAC digital-to-analog chip to increase by ΔI, and then executes step 13;

[0021] Step 13: Convert the pulse into a detectable pulse using a PD photodetector and send it to the FPGA controller to determine whether the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 7; otherwise, proceed to step 11.

[0022] Step 14: The FPGA controller determines whether the current operating current of the LD pump source exceeds Imax. If it does, proceed to step 15; otherwise, proceed to step 17.

[0023] Step 15: The FPGA controller determines whether the current temperature of the SAM semiconductor saturable absorber exceeds Tmax. If it does not exceed Tmax, proceed to step 18.

[0024] Step 17: The FPGA controller controls the LD current generated by the DAC digital-to-analog chip to increase by ΔI, and executes step 5;

[0025] Step 18: The FPGA controller controls the LD input current generated by the DAC digital-to-analog chip to be 0, controls the operating temperature of the TEC thermoelectric cooler to be T+ΔT, and executes step 19, where T is the current operating temperature of the TEC thermoelectric cooler;

[0026] Step 19: Monitor the temperature of the SAM semiconductor saturable absorber in real time using a temperature sensor. If the temperature reaches the range of T~(T+1)℃, proceed to step 4; otherwise, proceed to step 18.

[0027] Furthermore, in step 15, if the FPGA controller determines that the current temperature of the SAM semiconductor saturable absorber exceeds Tmax, then step 16 is executed:

[0028] Step 16: Determine whether the SAM position exceeds the radius limit of the SAM semiconductor saturable absorber. If it does, proceed to step 20; otherwise, proceed to step 21.

[0029] Step 20: Report the fault to the host computer interface;

[0030] Step 21: FPGA controller 9 controls motor 8 to change the position of SAM semiconductor saturable absorber, thus executing step 2.

[0031] Compared with the prior art, the present invention has the following advantages: (1) The method can collect the operating parameters of the laser mode-locking process in real time and quickly, and perform efficient data processing and analysis. It greatly improves the detection efficiency of adjusting the electrical control parameters and shortens the detection cycle. (2) The method can automatically complete the data collection, processing, analysis and parameter saving, reduce manual intervention and operation, and improve work efficiency. (3) The method adopts advanced sensor and data acquisition technology, which can realize the accurate measurement of electrical control parameters and improve the accuracy and reliability of detection. (4) The method can monitor the operating status of electrical control equipment in real time. Once an abnormality or potential fault is found, it can immediately report to the host computer and remind the operator to take timely measures to deal with it. (5) The method can reduce the dependence on debugging experience and greatly reduce the labor cost and time cost. (6) The method can use the product's own configuration to complete the intelligent detection of parameters, which greatly reduces the capital investment of high-precision instruments. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the intelligent parameter detection device for femtosecond lasers involved in Example 1.

[0033] Figure 2 is a flowchart of the intelligent parameter detection method for femtosecond lasers involved in Example 1.

[0034] Figure 3 is a flowchart of the fault repair process in the intelligent parameter detection method for femtosecond lasers involved in Example 2.

[0035] Figure 4 This is a schematic diagram of the host computer's interactive interface. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] like Figure 1 As shown, this embodiment relates to an intelligent parameter detection device for a femtosecond laser, which includes an LD pump source 1, a TWDM wavelength division multiplexer 2, a SAM semiconductor saturable absorber 3, a DAC digital-to-analog chip 4, a PD photodetector 5, a TEC thermoelectric cooler 6, a temperature sensor 7, a motor 8, an FPGA controller 9, and a parameter memory 10.

[0039] LD pump source 1 is used to generate laser light. LD pump source 1 is connected to the input of TWDM wavelength division multiplexer 2. The output of TWDM wavelength division multiplexer 2 is connected to SAM semiconductor saturable absorber 3 and PD photodetector 5, respectively. TWDM wavelength division multiplexer 2 splits the laser light into two paths: one path is sent to SAM semiconductor saturable absorber 3, and the other path is sent to PD photodetector 5 to convert the input optical signal into detectable pulses. PD photodetector 5 is connected to FPGA controller 9 to send the detectable pulses to FPGA controller 9 and determine the repetition frequency of the detectable pulses. Temperature sensor 7 is used to collect the temperature of SAM semiconductor saturable absorber 3 in real time. Temperature sensor 7 is connected to FPGA controller 9 to send the collected temperature to FPGA controller; TEC thermoelectric cooler 6 is connected to FPGA controller 9 to cool SAM semiconductor saturable absorber 3 based on control commands sent by FPGA controller 9; motor 8 is connected to FPGA controller 9 to change the position of semiconductor saturable absorber 3 under the control of FPGA controller 9; DAC digital-to-analog chip 4 is connected to FPGA controller 9 to input LD current to LD pump source 1 under the control of FPGA controller 9; parameter memory 10 is connected to FPGA controller 9 to store the final optimal mode-locking parameters, such as temperature and current.

[0040] The specific implementation process of the intelligent parameter detection method for a femtosecond laser of the present invention is as follows:

[0041] Step 1: Input the current optical path configuration temperature range Tmin~Tmax, SAM damage threshold Imin~Imax, and repetition rate range Fmin~Fmax through the host computer interface. After clicking "Start Detection", the information is sent to the FPGA controller 9 to execute Step 2.

[0042] Step 2: The FPGA controller 9 controls the TEC thermoelectric cooler 6 to operate at a temperature of Tmin. The TEC thermoelectric cooler 6 cools the SAM semiconductor saturable absorber 3. Step 3 is executed.

[0043] Step 3: Monitor the temperature of the SAM semiconductor saturable absorber 3 in real time using temperature sensor 7. If the temperature reaches the range of Tmin~(Tmin+1)℃, proceed to step 4; otherwise, proceed to step 3.

[0044] Step 4: The FPGA controller 9 controls the DAC digital-to-analog chip 4 to control the LD input current to Imin, which is sent to the LD pump source 1. The LD pump source 1 generates pump light. The TWDM wavelength division multiplexer 2 splits the pump light into a first pump light and a second pump light. The first pump light enters the SAM semiconductor saturable absorber 3 and generates a femtosecond laser pulse. The second pump light enters the PD photodetector 5 and the second pump light is sent to the PD photodetector 5. Step 5 is executed.

[0045] Step 5: The second pump light is converted into a detectable pulse by the PD photodetector 5 and sent to the FPGA controller 9 to detect whether the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 6; otherwise, proceed to step 14.

[0046] Step 6: Record the current temperature of TEC thermoelectric cooler 6 as T, the current operating current value of LD pump source 1 as IL, and then proceed to step 7;

[0047] Step 7: FPGA controller 9 determines whether the current operating current of LD pump source 1 exceeds Imax. If it does, proceed to step 8; otherwise, proceed to step 12.

[0048] Step 8: The FPGA controller 9 controls the LD input current generated by the DAC digital-to-analog chip 4 to be Imax, and then executes step 9;

[0049] Step 9: Convert the pulse into a detectable pulse using the PD photodetector 5, and send it to the FPGA controller 9 to check whether the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 10; otherwise, proceed to step 11.

[0050] Step 10: Record the current temperature of TEC thermoelectric cooler 6 as Ts, the current operating current of LD pump source 1 as IM, calculate Is=(IL+IM) / 2, save the result to the parameter memory, and end the detection; the stored parameters are the inherent parameters of the product and can be used directly when the product is turned on next time to ensure normal laser operation.

[0051] Step 11: Record the current temperature of TEC thermoelectric cooler 6 as Ts, the previously configured pump current value as IM, calculate Is=(IL+IM) / 2, save the result to the parameter memory, and end the detection;

[0052] Step 12: The FPGA controller 9 controls the pump input current generated by the DAC digital-to-analog chip 4 to increase by ΔI, and then executes step 13;

[0053] Step 13: Convert the pulse into a detectable pulse using the PD photodetector 5, and send it to the FPGA controller 9 to determine whether the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 7; otherwise, proceed to step 11.

[0054] Step 14: FPGA controller 9 determines whether the current operating current of LD pump source 1 exceeds Imax. If it does, proceed to step 15; otherwise, proceed to step 17.

[0055] Step 15: FPGA controller 9 determines whether the current temperature of SAM semiconductor saturable absorber 3 exceeds Tmax. If it does, proceed to step 16; otherwise, proceed to step 18.

[0056] Step 16: Report the fault to the host computer interface; The current temperature of SAM semiconductor saturable absorber 3 exceeds Tmax, indicating that a suitable operating current cannot be found at the maximum temperature;

[0057] Step 17: The FPGA controller 9 controls the LD current generated by the DAC digital-to-analog chip 4 to increase by ΔI, and then executes step 5;

[0058] Step 18: The FPGA controller 9 controls the LD input current generated by the DAC digital-to-analog chip 4 to be 0, controls the operating temperature of the TEC thermoelectric cooler 6 to be T+ΔT, and executes step 19, where T is the current operating temperature of the TEC thermoelectric cooler 6;

[0059] Step 19: Monitor the temperature of the SAM semiconductor saturable absorber 3 in real time using temperature sensor 7. If the temperature reaches the range of T~(T+1)℃, proceed to step 4; otherwise, proceed to step 18.

[0060] Example 2

[0061] In step 16 of Example 1, the current temperature of the SAM semiconductor saturable absorber 3 exceeds Tmax, indicating that a suitable operating current cannot be found at the maximum temperature. Therefore, a fault is reported to the host computer interface. This fault can be further repaired through the following steps. The specific implementation process of the fault repair method for the femtosecond laser is as follows:

[0062] Steps 1-15: Same as in Example 1;

[0063] Step 16: Determine whether the SAM position exceeds the radius limit of the SAM semiconductor saturable absorber. If it does, proceed to step 20; otherwise, proceed to step 21.

[0064] Steps 17-19: Same as in Example 1;

[0065] Step 20: Report the fault to the host computer interface;

[0066] Step 21: The FPGA controller 9 controls the motor 8 to change the position of the SAM semiconductor saturable absorber 3, thus executing step 2.

Claims

1. A smart parameter detection device for a femtosecond laser, characterized in that, The system includes an LD pump source, a TWDM wavelength division multiplexer, a SAM semiconductor saturable absorber, a DAC digital-to-analog converter, a PD photodetector, a TEC thermoelectric cooler, a temperature sensor, a motor, an FPGA controller, and a parameter memory. The LD pump source generates laser light and is connected to the input of the TWDM. The output of the TWDM is connected to both the SAM semiconductor saturable absorber and the PD photodetector. The TWDM splits the laser light into two paths: one path is sent to the SAM semiconductor saturable absorber, and the other path is sent to the PD photodetector to convert the input light signal into a detectable pulse. The PD photodetector is connected to the FPGA controller. The system consists of a sensor connected to the FPGA controller to send detectable pulses to determine the repetition frequency of the detectable pulses; a temperature sensor to collect the temperature of the SAM semiconductor saturable absorber in real time, and connected to the FPGA controller to send the collected temperature to the FPGA controller; a TEC thermoelectric cooler connected to the FPGA controller to cool the SAM semiconductor saturable absorber based on control commands from the FPGA controller; a motor connected to the FPGA controller to change the position of the semiconductor saturable absorber under the control of the FPGA controller; and a DAC digital-to-analog chip connected to the FPGA controller to input LD current to the LD pump source under the control of the FPGA controller.

2. A method for detecting parameters of an intelligent device based on the femtosecond laser of claim 1, characterized in that, Includes the following steps: Step 1: Input the current optical path configuration temperature range Tmin~Tmax, SAM damage threshold Imin~Imax, and repetition rate range Fmin~Fmax through the host computer interface. After clicking "Start Detection", the information is sent to the FPGA controller to execute Step 2. Step 2: The FPGA controller controls the TEC thermoelectric cooler to operate at a temperature of Tmin. The TEC thermoelectric cooler cools the SAM semiconductor saturable absorber. Step 3 is then executed. Step 3: Monitor the temperature of the SAM semiconductor saturable absorber in real time using a temperature sensor. If the temperature reaches the range of Tmin ~ (Tmin+1)℃, proceed to step 4; otherwise, proceed to step 3. Step 4: The FPGA controller controls the DAC digital-to-analog chip to control the LD input current to Imin, which is sent to the LD pump source. The LD pump source generates pump light. The TWDM wavelength division multiplexer splits the pump light into a first pump light and a second pump light. The first pump light enters the SAM semiconductor saturable absorber and generates a femtosecond laser pulse. The second pump light enters the PD photodetector and executes step 5. Step 5: The second pump light is converted into a detectable pulse by the PD photodetector and sent to the FPGA controller to detect whether the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 6; otherwise, proceed to step 14. Step 6: Record the current temperature of the TEC thermoelectric cooler as T, the current operating current of the LD pump source as IL, and then proceed to step 7; Step 7: The FPGA controller determines whether the current operating current of the LD pump source exceeds Imax. If it does, proceed to step 8; otherwise, proceed to step 12. Step 8: The FPGA controller controls the LD input current generated by the DAC digital-to-analog chip to be Imax, and then executes step 9; Step 9: Convert the pulse into a detectable pulse using a PD photodetector and send it to the FPGA controller to check if the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 10; otherwise, proceed to step 11. Step 10: Record the current temperature of the TEC thermoelectric cooler as Ts, the current operating current of the LD pump source as IM, calculate Is=(IL+IM) / 2, save the result to the parameter memory, and end the detection; the stored parameters are the inherent parameters of the product and can be used directly when the product is turned on next time to ensure normal laser operation. Step 11: Record the current temperature of the TEC thermoelectric cooler as Ts, the previously configured pump current value as IM, calculate Is=(IL+IM) / 2, save the result to the parameter memory, and end the detection; Step 12: The FPGA controller controls the pump input current generated by the DAC digital-to-analog chip to increase by ΔI, and then executes step 13; Step 13: Convert the pulse into a detectable pulse using a PD photodetector and send it to the FPGA controller to determine whether the pulse repetition frequency is within the range of Fmin~Fmax. If it is within the range, proceed to step 7; otherwise, proceed to step 11. Step 14: The FPGA controller determines whether the current operating current of the LD pump source exceeds Imax. If it does, proceed to step 15; otherwise, proceed to step 17. Step 15: The FPGA controller determines whether the current temperature of the SAM semiconductor saturable absorber exceeds Tmax. If it does not exceed Tmax, proceed to step 18. Step 17: The FPGA controller controls the LD current generated by the DAC digital-to-analog chip to increase by ΔI, and executes step 5; Step 18: The FPGA controller controls the LD input current generated by the DAC digital-to-analog chip to be 0, controls the operating temperature of the TEC thermoelectric cooler to be T+ΔT, and executes step 19, where T is the current operating temperature of the TEC thermoelectric cooler; Step 19: Monitor the temperature of the SAM semiconductor saturable absorber in real time using a temperature sensor. If the temperature reaches the range of T~(T+1)℃, proceed to step 4; otherwise, proceed to step 18.

3. The detection method of the intelligent parameter device based on the femtosecond laser of claim 1 according to claim 1, characterized in that, If the FPGA controller determines in step 15 that the current temperature of the SAM semiconductor saturable absorber exceeds Tmax, then step 16 is executed: Step 16: Determine whether the SAM position exceeds the radius limit of the SAM semiconductor saturable absorber. If it does, proceed to step 20; otherwise, proceed to step 21. Step 20: Report the fault to the host computer interface; Step 21: FPGA controller 9 controls motor 8 to change the position of SAM semiconductor saturable absorber, thus executing step 2.

Images