Green picosecond laser system and control method thereof

Abstract

The embodiment of the invention provides a green-light picosecond laser system and a control method thereof, and relates to the technical field of ultrafast laser, and the method comprises the following steps: receiving the laser power of seed laser detected by a first power detection assembly; receiving the laser power of the amplified laser detected by the second power detection assembly; executing any one of the following steps according to a user instruction: judging whether the number of pulse strings of the seed laser is consistent with the number of pulse strings of the P polarization green light, and if so, receiving the laser power of the P polarization green light; judging whether the laser power of the P polarization green light is a first preset value or not, and if not, outputting an adjusting signal to a power adjusting assembly; or, judging whether the number of pulse strings of the seed laser is consistent with the number of pulse strings of the S polarization green light, and if so, receiving the laser power of the S polarization green light; and judging whether the laser power of the S polarization green light is a first preset value, and if not, outputting an adjustment signal to the power adjustment assembly.

Description

Technical Field

[0001] The present application relates to the field of ultrafast laser technology, and in particular, to a green picosecond laser system and a control method thereof. Background Art

[0002] In the fields of polarization-sensitive material processing and optical sensing, the polarization characteristics of green picosecond lasers directly affect the application effects. For anisotropic or layered structure materials, lasers with different polarization directions (such as P polarization and S polarization) will trigger different processing characteristics, which are specifically manifested as significant changes in parameters such as slit morphology, melting depth, and surface roughness. At the same time, in the field of polarization optical measurement, green lasers are widely used in precision sensing scenarios such as ellipsometry and micro-vibration interference detection due to their high quantum efficiency on photodetectors such as CCD / CMOS. Such applications have clear requirements for the independent controllability of the polarization state of the light source.

[0003] In related technologies, green picosecond lasers mainly adopt a single polarization state frequency doubling technology architecture, and their phase matching mechanism and resonator design are optimized around a single polarization state (P polarization or S polarization). Existing green picosecond lasers usually achieve efficient second harmonic conversion of specific polarized light through the adjustment of the angle of the nonlinear crystal and temperature matching, and the layout of optical components strictly follows the design of the single polarization state propagation path.

[0004] However, since a green picosecond laser cannot simultaneously and separately control the output of frequency-doubled light with different polarization states, users need to perform multiple polarization beam splitters and sequential processing in polarization-sensitive applications, significantly reducing the processing or detection efficiency. Summary of the Invention

[0005] Embodiments of the present application provide a green picosecond laser system and a control method thereof to solve the technical problems in related technologies that traditional green picosecond lasers cannot simultaneously and separately control the output of frequency-doubled light with different polarization states and have low processing and detection efficiency.

[0006] In a first aspect, embodiments of the present application provide a control method for a green picosecond laser system, including the following steps:

[0007] Receiving the laser power of the seed laser detected by the first power detection component; wherein, the seed laser is the laser signal output by the seed source module;

[0008] Judging whether the laser power of the seed laser is within a first preset power range;

[0009] If the laser power of the seed laser is within the preset power range, then turn on the amplification module to amplify the power of the seed laser to form amplified laser;

[0010] Receiving the laser power of the amplified laser detected by the second power detection component;

[0011] Determine whether the laser power of the amplified laser is within the second preset power range. If the laser power of the amplified laser is within the second preset power range, then perform any of the following steps according to the user instruction;

[0012] Receive the number of pulse trains of the seed laser detected by the first pulse train detection component and the number of pulse trains of the P-polarized green light detected by the second pulse train detection component respectively;

[0013] Determine whether the number of pulse trains of the seed laser is the same as the number of pulse trains of the P-polarized green light. If they are the same, then receive the laser power of the P-polarized green light output by the third power detection component;

[0014] Determine whether the laser power of the P-polarized green light is the first predetermined value. If not, then output an adjustment signal to the power adjustment component;

[0015] Alternatively, receive the number of pulse trains of the seed laser output by the first pulse train detection component and the number of pulse trains of the S-polarized green light output by the second pulse train detection component respectively;

[0016] Determine whether the number of pulse trains of the seed laser is the same as the number of pulse trains of the S-polarized green light. If they are the same, then receive the laser power of the S-polarized green light output by the third power detection component;

[0017] Determine whether the laser power of the S-polarized green light is the first predetermined value. If not, then output an adjustment signal to the power adjustment component.

[0018] In a feasible implementation manner, determine whether the laser power of the P-polarized green light is the first predetermined value. If not, then output an adjustment signal to the power adjustment component; specifically including the following steps:

[0019] Determine whether the laser power of the P-polarized green light is the first predetermined value. If not, then output an adjustment signal to the power adjustment component; if so, then turn off the second optical switch and output the P-polarized green light;

[0020] Determine whether the laser power of the S-polarized green light is the second predetermined value. If not, then output an adjustment signal to the power adjustment component; specifically including the following steps:

[0021] Determine whether the laser power of the S-polarized green light is the second predetermined value. If not, then output an adjustment signal to the power adjustment component; if so, then turn off the first optical switch and output the S-polarized green light.

[0022] In a feasible implementation manner, receive the laser power of the amplified laser detected by the second power detection component;

[0023] Determine whether the laser power of the amplified laser is within the second preset power range; specifically including the following steps:

[0024] Receive the laser power of the first laser; wherein, the first laser is the laser signal output by the first amplification module, and the laser power of the first laser is the laser power detected by the second photodetector;

[0025] Determine whether the laser power of the first laser is within the preset intermediate laser power range;

[0026] If the laser power of the first laser is within the preset intermediate laser power range, turn on the second amplification module, and the second amplification module amplifies the power of the first laser to form amplified laser;

[0027] Receive the laser power of the amplified laser;

[0028] Determine whether the laser power of the second laser is within the second preset power range.

[0029] In a feasible implementation manner, the control method includes:

[0030] Receive the crystal temperature of the first laser crystal output by the first temperature sensor;

[0031] Determine whether the crystal temperature of the first laser crystal is within the first temperature range;

[0032] If the crystal temperature of the first laser crystal is within the first temperature range, start the PID algorithm, and use the first thermoelectric cooler to adjust the temperature of the first laser crystal to the first optimal temperature, so as to amplify the seed laser within the optimal temperature range in the first amplification module to form the first laser;

[0033] Receive the crystal temperature of the second laser crystal output by the second temperature sensor;

[0034] Determine whether the crystal temperature of the second laser crystal is within the second temperature range;

[0035] If the crystal temperature of the second laser crystal is within the second temperature range, start the PID algorithm, and use the second thermoelectric cooler to adjust the temperature of the second laser crystal to the second optimal temperature, so as to amplify the first laser within the optimal temperature range in the second amplification module to form the amplified laser.

[0036] In a second aspect, an embodiment of the present application further provides a green picosecond laser system. The green picosecond laser system adopts the control method of a green picosecond laser system disclosed in the first aspect. The green picosecond laser system includes: a seed source module, an amplification module, an output module, and an electronic control module;

[0037] The electronic control module includes an electronic control component, a first power detection component, a second power detection component, a third power detection component, a first pulse train detection component, and a second pulse train detection component that are respectively signal-connected to the electronic control component; the electronic control component is further configured to provide power to the picosecond laser system;

[0038] The seed source module is used to generate seed laser; the first power detection component and the first pulse train detection component are arranged downstream of the optical path of the seed source module; the first power detection component is used to detect the laser power of the seed laser; the first pulse train detection component is used to detect the number of pulses of the seed laser;

[0039] The amplification module is arranged downstream of the optical path of the seed source module, and the amplification module is used to amplify the power of the seed laser to form amplified laser; the output module and the second power detection component are both arranged downstream of the optical path of the amplification module; the second power detection component is used to detect the laser power of the amplified laser;

[0040] The output module is arranged downstream of the optical path of the amplification module. The output module includes a power adjustment component and a switchable output channel arranged in sequence along the output optical path of the amplified laser. The switchable output channel is provided with a frequency doubling crystal; the power adjustment component is configured to modulate the laser power of the amplified laser to a predetermined power value, and then output P-polarized green light or S-polarized green light after frequency doubling by the frequency doubling crystal of the switchable output channel; the third power detection component is respectively arranged downstream of the optical path of the frequency doubling crystal to detect the laser power of the P-polarized green light, or the laser power of the S-polarized green light, and the second pulse train detection component is arranged downstream of the optical path of the frequency doubling crystal to detect the number of pulse trains of the P-polarized green light, or the number of pulse trains of the S-polarized green light;

[0041] The electronic control component is configured to judge whether the laser power of the P-polarized green light is a first predetermined value when the laser power of the seed laser and the laser power of the amplified laser are both within a preset power range and the number of pulse trains of the seed laser is consistent with the number of pulse trains of the P-polarized green light, or the electronic control module is configured to judge whether the laser power of the S-polarized green light is a second predetermined value when the laser power of the seed laser and the laser power of the amplified laser are both within a preset power range and the number of pulses of the seed laser is consistent with the number of pulses of the S-polarized green light;

[0042] If the laser power of the P-polarized green light is not the first predetermined value or the laser power of the S-polarized green light is not the second predetermined value, an adjustment signal is output to the power adjustment component.

[0043] In a feasible implementation manner, the output module further includes a polarization beam splitter prism;

[0044] The switchable output channel includes a fourth focusing lens, a first frequency doubling crystal, a third collimating lens, a first window mirror, a fifth focusing lens, a second frequency doubling crystal, a fourth collimating lens, and a second window mirror;

[0045] The polarization beam splitter prism is disposed on the output side of the power adjustment component. The fourth focusing lens is disposed on the first output side of the polarization beam splitter prism to output the first target laser. The fourth focusing lens, the first frequency doubling crystal, the third collimating lens, and the first window mirror are arranged along the output path of the first target laser. The fourth focusing lens is configured to focus the first target laser onto the first frequency doubling crystal. The first frequency doubling crystal is configured to convert the first target laser into P-polarized frequency-doubled laser, which is then collimated by the third collimating lens and output through the first window mirror;

[0046] The fifth focusing lens is disposed on the second output side of the polarization beam splitter prism to output the second target laser. The fifth focusing lens, the second frequency doubling crystal, the fourth collimating lens, and the second window mirror are arranged along the output path of the second target laser. The fifth focusing lens is configured to focus the second target laser onto the second frequency doubling crystal. The second frequency doubling crystal is configured to convert the second target laser into S-polarized frequency-doubled laser, which is then collimated by the fourth collimating lens and output through the second window mirror.

[0047] In a feasible implementation, the output module further includes a first optical switch and a second optical switch;

[0048] The first optical switch is disposed between the polarization beam splitter prism and the fourth focusing lens, and the second optical switch is disposed between the polarization beam splitter prism and the fifth focusing lens. Wherein, the first optical switch is configured to turn on or off the P-polarization channel, and the second optical switch is configured to turn on or off the S-polarization channel.

[0049] In a feasible implementation, the picosecond laser system includes a first beam splitter, a second beam splitter, a third beam splitter, a fourth beam splitter, and a fifth beam splitter;

[0050] The third power detection component includes a fourth photodetector and a fifth photodetector, and the second pulse train detection component includes a second oscilloscope and a third oscilloscope;

[0051] The first beam splitter is disposed on the output side of the third collimating lens. The first pulse train detection component is disposed on the transmission side of the first beam splitter to detect the number of pulses of the P-polarized green light. The second beam splitter is disposed on the reflection side of the first beam splitter. The fourth photodetector is disposed on the reflection side of the second beam splitter to detect the P-polarization power of the P-polarized green light. The first window mirror is disposed on the transmission side of the second beam splitter;

[0052] The third beam splitter is disposed on the second output side of the polarization beam splitter prism, the fourth beam splitter is disposed on the output side of the fourth collimating lens, the second oscilloscope is disposed on the transmission side of the fourth beam splitter for detecting the S-polarized power of the S-polarized green light, the fifth beam splitter is disposed on the reflection side of the fourth beam splitter, the fifth photodetector is disposed on the reflection side of the fifth beam splitter for detecting the polarization power of the S-polarized green light, and the second window mirror is disposed on the transmission side of the fifth beam splitter.

[0053] In a feasible implementation, the picosecond laser system includes a first beam splitting component, a second beam splitting component, and a third beam splitting component, the amplification module includes a first amplification module and a second amplification module; the second power detection component includes a second photodetector and a third photodetector;

[0054] The first beam splitting component is disposed on the output side of the seed source module, the first amplification module is disposed on the transmission side of the first beam splitting component, and the first power detection component and the first pulse train detection component are disposed on the reflection side of the first beam splitting component;

[0055] The first amplification module includes a first crystal component and a first pump, the first pump is configured to form a first pump light, the incident direction of the first pump light and the incident direction of the seed laser are oppositely arranged, and the seed laser forms a first laser in the first crystal component through pumping by the first pump light;

[0056] The second beam splitting component is disposed on the output side of the first amplification module, the second amplification module is disposed on the reflection side of the second beam splitting component, and the second photodetector is disposed on the transmission side of the second amplification module to detect the laser power of the first laser;

[0057] The second amplification module includes a second crystal component and a second pump, the second pump is configured to form a second pump light, the incident direction of the second pump light and the incident direction of the first laser are oppositely arranged, and the first laser forms an amplified laser in the second crystal component through pumping by the second pump light;

[0058] The third beam splitting component is disposed on the output side of the second amplification module, the third photodetector is disposed on the transmission side of the second beam splitting component to detect the laser power of the amplified laser, and the output module is disposed on the reflection side of the third beam splitting component.

[0059] In a feasible implementation, the first crystal component includes a first laser crystal, a first heat sink, a first thermoelectric cooler, a first liquid cooling radiator, and a first temperature sensor; the two first heat sinks are respectively disposed on both sides of the first laser crystal to support the first laser crystal, the first thermoelectric cooler is disposed on one side of one of the first heat sinks to adjust the temperature of the first laser crystal, the first liquid cooling radiator is disposed on one side of the first thermoelectric cooler to dissipate heat from the first thermoelectric cooler; the first temperature sensor is disposed on the first heat sink to monitor the temperature of the first laser crystal in real time;

[0060] The second crystal assembly includes a second laser crystal, a second heat sink, a second thermoelectric cooler, a second liquid-cooled radiator, and a second temperature sensor; there are two second laser crystals, and the two second laser crystals are arranged side by side; the two second heat sinks are respectively arranged on both sides of the second laser crystal to support the second laser crystal, the second thermoelectric cooler is arranged on one side of one of the second heat sinks to adjust the temperature of the second laser crystal, and the second liquid-cooled radiator is arranged on one side of the second thermoelectric cooler to dissipate heat from the second thermoelectric cooler; the second temperature sensor is arranged on the second heat sink to monitor the temperature of the second laser crystal in real time;

[0061] The first thermoelectric cooler, the first temperature sensor, the second thermoelectric cooler, and the second temperature sensor are respectively connected to the electronic control component in a signal manner.

[0062] In a first aspect, an embodiment of the present application provides a control method for a green picosecond laser system. In the embodiment of the present application, by respectively receiving the laser power of the seed laser and the laser power of the amplified laser, and judging the laser power of the seed laser and the laser power of the amplified laser one by one, the stability of the laser power output to the output module can be ensured; further, when the user needs to output P-polarized green light with a first predetermined value of laser power, the electronic control component receives and judges the laser power of the P-polarized green light, and outputs an adjustment signal to the power adjustment component according to the laser power of the P-polarized green light to adjust the laser power of the P-polarized green light until the P-polarized green light with the first predetermined value is output; when the user needs to output S-polarized green light with a second predetermined value of laser power, the electronic control component receives and judges the laser power of the S-polarized green light, and outputs an adjustment signal to the power adjustment component according to the laser power of the S-polarized green light to adjust the laser power of the S-polarized green light until the S-polarized green light with the second predetermined value is output; that is, through the setting of the present application, the P-polarized green light and the S-polarized green light in the green picosecond laser system can be switched and output according to the preset power, which facilitates the use of the user and improves the processing efficiency. Furthermore, in the embodiment of the present application, by receiving and judging the number of pulse trains of the seed laser and the number of pulse trains of the P-polarized green light / the number of pulse trains of the S-polarized green light, the polarized light with a predetermined number of pulses of the P-polarized green light / S-polarized green light can be ensured, so that the polarized light with different pulse trains can be output according to the user's needs, which not only meets the requirements for high-power multi-pulses, but also provides a more flexible and diverse laser output mode, facilitating the use of the user.

[0063] Second aspect, the embodiments of the present application further provide a green picosecond laser system. In the green picosecond laser system, through the setting of the frequency doubling component, the frequency doubling output of P-polarized green light and S-polarized green light is realized. Due to the influence of environmental factors, the frequency doubling component will change dynamically during the frequency doubling process, resulting in large fluctuations in the laser power of the output polarized green light. Through the setting of the first power detection component and the second power detection component in the embodiments of the present application, the laser power of the seed laser and the laser power of the amplified laser can be respectively received by the electronic control component, and the laser power of the seed laser and the laser power of the amplified laser can be judged one by one, so as to ensure the stability of the laser power output to the output module; further, when the user needs to output P-polarized green light with a first predetermined value of laser power, the electronic control component receives and judges the laser power of the P-polarized green light, and outputs an adjustment signal to the power adjustment component according to the laser power of the P-polarized green light to adjust the laser power of the P-polarized green light until the P-polarized green light with the first predetermined value is output; when the user needs to output S-polarized green light with a second predetermined value of laser power, the electronic control component receives and judges the laser power of the S-polarized green light, and outputs an adjustment signal to the power adjustment component according to the laser power of the S-polarized green light to adjust the laser power of the S-polarized green light until the S-polarized green light with the second predetermined value is output; that is, through the setting of the present application, the power fluctuation caused by the frequency doubling component can be overcome, and the P-polarized green light and the S-polarized green light in the green picosecond laser system can be switched output according to the preset power, which is convenient for users to use and improves the processing efficiency. Furthermore, in the embodiments of the present application, through the setting of the first pulse train detection component and the second pulse train detection component, the electronic control component can receive and judge the number of pulse trains of the seed laser and the number of pulse trains of the P-polarized green light / S-polarized green light, so as to ensure that the polarized light with a predetermined number of pulses is output for the P-polarized green light / S-polarized green light, and thus different pulse train polarized lights can be output according to the needs of the user, which not only meets the requirements for high-power multi-pulses, but also provides a more flexible and diverse laser output mode, facilitating the use of users. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present application and do not constitute an improper limitation of the present invention. In the drawings:

[0065] Figure 1 is a schematic structural diagram of a green picosecond laser system provided by an embodiment of the present application;

[0066] Figure 2 is Figure 1 the schematic structural diagram of the first crystal component in;

[0067] Figure 3 isFigure 1 Schematic diagram of the structure of the second crystal component in

[0068] Figure 4 Method flow of a control method for a green picosecond laser system provided by an embodiment of the present application Figure 1 ;

[0069] Figure 5 is Figure 4 Specific step diagram of S14 - S15 in

[0070] Figure 6 Method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 2 ;

[0071] Figure 7 Method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 3 ;

[0072] Figure 8 Fitting curve graph of output power and pulse number;

[0073] Figure 9 Output wavelength data graph of P - polarized green light;

[0074] Figure 10 Output pulse width data graph of P - polarized green light;

[0075] Figure 11 Output power and stability data graph of P - polarized green light;

[0076] Figure 12 Output power and stability data graph of S - polarized green light;

[0077] Figure 13 3 - pulse data graph of the target laser;

[0078] Figure 14 9 - pulse data graph of the target laser.

[0079] Explanation of reference numerals:

[0080] 100 - Seed source module; 200 - First amplification module; 300 - Second amplification module; 400 - Output module; 800 - Second beam splitting component;

[0081] 110 - Picosecond seed source; 120 - Fiber collimator; 130 - First opto - isolator;

[0082] 210 - First crystal assembly; 211 - First laser crystal; 212 - First heat sink; 213 - First thermoelectric cooler; 214 - First liquid-cooled radiator; 214a - First liquid inlet; 214b - First liquid outlet; 215 - First temperature sensor; 220 - First dichroic mirror; 230 - First focusing lens; 240 - First collimating lens; 250 - First pump

[0083] 310 - Second crystal assembly; 311 - Second laser crystal, 312 - Second heat sink, 313 - Second thermoelectric cooler, 314 - Second liquid-cooled radiator, 314a - Second liquid inlet; 314b - Second liquid outlet; 315 - Second temperature sensor; 320 - Second dichroic mirror; 330 - Second focusing lens; 340 - Second collimating lens; 350 - Second pump

[0084] 410 - Power adjustment assembly; 420 - Polarizing beam splitter prism; 430 - Switchable output channel; 431 - First optical switch; 432 - Fourth focusing lens; 433 - First frequency doubling crystal; 434 - Third collimating lens; 430a - First window mirror; 435 - Second optical switch; 436 - Fifth focusing lens; 437 - Second frequency doubling crystal; 438 - Fourth collimating lens; 430b - Second window mirror; 440a - Third mirror; 440b - Third optical trap; 450a - Fourth mirror; 450b - Fourth optical trap

[0085] 510 - Electric control assembly; 520 - First photodetector; 530 - Second photodetector; 540 - Third photodetector; 550 - Fourth photodetector; 560 - Fifth photodetector; 570 - First oscilloscope; 580 - Second oscilloscope; 590 - Third oscilloscope

[0086] 610 - First beam splitter; 620 - Second beam splitter; 630 - Third beam splitter; 640 - Fourth beam splitter; 650 - Fifth beam splitter

[0087] 710 - Sixth beam splitter; 720 - Seventh beam splitter

[0088] 810 - Second opto-isolator; 820 - Second focusing lens; 830 - Eighth beam splitter

[0089] 910 - Ninth beam splitter Detailed implementation mode

[0090] To enable those skilled in the art to better understand the technical solutions in this application, the following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0091] In the fields of polarization-sensitive material processing and optical sensing, the polarization characteristics of green picosecond lasers directly affect the application effects. For anisotropic or layered-structured materials, lasers with different polarization directions (such as P polarization and S polarization) will trigger different processing characteristics, which are specifically manifested as significant changes in parameters such as slit morphology, melting depth, and surface roughness. At the same time, in the field of polarization optical measurement, green lasers, due to their high quantum efficiency on photodetectors such as CCD / CMOS, are widely used in precision sensing scenarios such as ellipsometry and micro-vibration interference detection. Such applications have clear requirements for the independent controllability of the polarization state of the light source.

[0092] The green picosecond laser system mainly adopts a single-polarization-state frequency doubling technology architecture, and its phase matching mechanism and resonator design are optimized around a single polarization state (P polarization or S polarization). Existing green picosecond lasers usually achieve efficient second-harmonic conversion of specific polarized light through the adjustment of the angle of the nonlinear crystal and temperature matching, and the layout of optical components strictly follows the design of the single-polarization-state propagation path.

[0093] However, since the green picosecond laser system cannot simultaneously and separately control the output of frequency-doubled light with different polarization states, users need to perform multiple polarization beam splitters and sequential processing in polarization-sensitive applications, significantly reducing the processing or detection efficiency.

[0094] In specific implementation, when environmental factors (such as temperature fluctuations, laser power fluctuations, etc.) cause dynamic changes in the frequency doubling process, it is difficult to compensate for these external interferences in a timely manner by manual adjustment alone, resulting in relatively large fluctuations in the output power. For example, when the ambient temperature rises slightly, the crystal temperature control system may not be able to respond in a timely manner, resulting in a change in the phase matching condition, thereby causing a decrease or fluctuation in the output power, and manual adjustment cannot achieve real-time feedback and control.

[0095] Therefore, the embodiments of this application provide a green picosecond laser system and its control method to solve the technical problem in the related art that since the green picosecond laser system cannot simultaneously and separately control the output of frequency-doubled light with different polarization states, users need to perform multiple polarization beam splitters and sequential processing in polarization-sensitive applications, significantly reducing the processing or detection efficiency.

[0096] Figure 1It is a schematic structural diagram of a green picosecond laser system provided by an embodiment of the present application.

[0097] Referring to Figure 1 , an embodiment of the present application provides a green picosecond laser system. The picosecond laser system includes: a seed source module 100, an amplification module, an output module 400, and an electronic control module;

[0098] The electronic control module includes an electronic control component 510 and a first power detection component, a second power detection component, a third power detection component, a first pulse train detection component, and a second pulse train detection component that are respectively connected to the electronic control module in a signal connection manner; the electronic control module is further configured to provide power to the picosecond laser system;

[0099] The seed source module 100 is used to generate seed laser; the first power detection component and the first pulse train detection component are arranged downstream of the optical path of the seed source module 100; the first power detection component is used to detect the laser power of the seed laser; the first pulse train detection component is used to detect the number of pulses of the seed laser;

[0100] The amplification module is arranged downstream of the optical path of the seed source module 100. The amplification module is used to amplify the power of the seed laser to form amplified laser; the output module 400 and the second power detection component are both arranged downstream of the optical path of the amplification module; the second power detection component is used to detect the laser power of the amplified laser;

[0101] The output module 400 is arranged downstream of the optical path of the amplification module. The output module 400 includes a power adjustment component 410, a frequency doubling output module 400, and a switchable output channel 430 that are arranged in sequence along the output optical path of the amplified laser; the power adjustment component 410 is configured to modulate the laser power of the amplified laser to a predetermined power value, and then output P-polarized green light or S-polarized green light through the switchable output channel 430 after frequency doubling by a frequency doubling crystal; the third power detection component is respectively arranged downstream of the optical path of the frequency doubling crystal to detect the laser power of the P-polarized green light or the S-polarized green light, and the second pulse train detection component is arranged downstream of the optical path of the frequency doubling crystal to detect the number of pulse trains of the P-polarized green light or the number of pulse trains of the S-polarized green light;

[0102] The electronic control component 510 is configured to determine whether the laser power of the P-polarized green light is a first predetermined value when the laser power of the seed laser and the laser power of the amplified laser are both within a preset power range and the number of pulse trains of the seed laser is the same as the number of pulse trains of the P-polarized green light, or the electronic control module is configured to determine whether the laser power of the S-polarized green light is a second predetermined value when the laser power of the seed laser and the laser power of the amplified laser are both within a preset power range and the number of pulses of the seed laser is the same as the number of pulses of the S-polarized green light;

[0103] If the laser power of the P-polarized green light is not the first predetermined value or the laser power of the S-polarized green light is not the second predetermined value, an adjustment signal is output to the power adjustment component 410.

[0104] Exemplarily, the power adjustment component 410 includes a motor and a half-wave plate disposed at the rotating end of the motor. The motor is in signal connection with the electronic control component 510, and the electronic control component 510 is configured to modulate and amplify the laser power by controlling the rotation angle of the motor. For example, the coating center wavelength of the half-wave plate is 1064 nm, and the angle of the half-wave plate is adjusted by the motor to achieve adjustable energy at a wavelength of 532 nm.

[0105] In specific implementation, a micro-drive technology can be adopted, that is, the motor is controlled to rotate 0.5° each time, so that the splitting ratio of the polarization beam splitter 420 can be accurately regulated, and the effective optical power entering the frequency doubling crystal can be made more stable.

[0106] In some examples, the seed source module 100 includes a picosecond seed source 110, an optical fiber collimator 120, and a first opto-electronic isolator 130 sequentially arranged along the seed laser transmission path. Among them, the first seed laser output by the picosecond seed source 110 is collimated by the optical fiber collimator 120 to obtain a seed laser, and the laser spot diameter of the collimated seed laser is 100 μm to 400 μm, and the collimated laser spot diameter is set as D1. The first opto-electronic isolator 130 is used to isolate the laser returned from the device on its output side to avoid damage to the device on the output side of the first opto-electronic isolator 130.

[0107] For example, the picosecond seed source 110 can be set as a laser with a center wavelength of 1064 nm, a pulse width of 10.2 ps, a beam quality factor M 2 <1.1, and a repetition frequency adjustable in the range of 500 Hz to 15 MHz.

[0108] From the above description, it can be seen that the following technical effects are achieved by this solution:

[0109] The embodiment of the present application also provides a green picosecond laser system. In the green picosecond laser system, through the setting of the frequency doubling component, the frequency doubling output of P-polarized green light and S-polarized green light is realized. Due to the influence of environmental factors, the frequency doubling component will change dynamically during the frequency doubling process, resulting in a large fluctuation in the laser power of the output polarized green light. Through the setting of the first power detection component and the second power detection component, the embodiment of the present application can respectively receive the laser power of the seed laser and the amplified laser through the electronic control component 510, and judge the laser power of the seed laser and the amplified laser one by one, so as to ensure the stability of the laser power output to the output module 400; further, when the user needs to output P-polarized green light with a first predetermined value of laser power, the electronic control component 510 receives and judges the laser power of the P-polarized green light, and outputs an adjustment signal to the power adjustment component 410 according to the laser power of the P-polarized green light to adjust the laser power of the P-polarized green light until the P-polarized green light with the first predetermined value is output; when the user needs to output S-polarized green light with a second predetermined value of laser power, the electronic control component 510 receives and judges the laser power of the S-polarized green light, and outputs an adjustment signal to the power adjustment component 410 according to the laser power of the S-polarized green light to adjust the laser power of the S-polarized green light until the S-polarized green light with the second predetermined value is output; that is, through the setting of the present application, the power fluctuation caused by the frequency doubling component can be overcome, and the P-polarized green light and S-polarized green light in the green picosecond laser system can be switched and output according to the preset power, which is convenient for users to use and improves the processing efficiency. Furthermore, in the embodiment of the present application, through the setting of the first pulse train detection component and the second pulse train detection component, the electronic control component 510 can receive and judge the number of pulse trains of the seed laser and the number of pulse trains of the P-polarized green light / S-polarized green light, so as to ensure that the polarized light with a predetermined number of pulses is output for the P-polarized green light / S-polarized green light, and thus different pulse train polarized lights can be output according to the needs of the user, which not only meets the requirements for high-power multi-pulses, but also provides a more flexible and diverse laser output mode, facilitating the use of users.

[0110] In some embodiments, the output module 400 further includes a polarization beam splitter prism 420;

[0111] The switchable output channel 430 includes a fourth focusing lens 432, a first frequency doubling crystal 433, a third collimating lens 434, a fifth focusing lens 436, a second frequency doubling crystal 437, a fourth collimating lens 438 and a second window mirror 430b;

[0112] The polarization beam splitter prism 420 is disposed on the output side of the power adjustment assembly 410. The fourth focusing lens 432 is disposed on the first output side of the polarization beam splitter prism 420 to output the first target laser. The fourth focusing lens 432, the first frequency doubling crystal 433, the third collimating lens 434, and the first window mirror 430a are arranged along the output path of the first target laser. The fourth focusing lens 432 is configured to focus the first target laser onto the first frequency doubling crystal 433. The first frequency doubling crystal 433 is configured to convert the first target laser into P-polarized frequency-doubled laser, which is then collimated by the third collimating lens 434 and output through the first window mirror 430a.

[0113] The fifth focusing lens 436 is disposed on the second output side of the polarization beam splitter prism 420 to output the second target laser. The fifth focusing lens 436, the second frequency doubling crystal 437, the fourth collimating lens 438, and the second window mirror 430b are arranged along the output path of the second target laser. The fifth focusing lens 436 is configured to focus the second target laser onto the second frequency doubling crystal 437. The second frequency doubling crystal 437 is configured to convert the second target laser into S-polarized frequency-doubled laser, which is then collimated by the fourth collimating lens 438 and output through the second window mirror 430b.

[0114] Exemplarily, the polarization beam splitter prism 420 is configured to split the beam modulated by the power adjustment assembly 410 into P-polarized light and S-polarized light.

[0115] Further, the first frequency doubling crystal 433 receives P-polarized light, and the P-polarized light generates 532-nm frequency-doubled laser through the first frequency doubling crystal 433. In a specific implementation, the first frequency doubling crystal 433 uses an LBO (lithium triborate) crystal, with a crystal size of 5×5×14 mm 3 , the crystal cutting angle is θ = 90°, φ = 10.4°, the transmittance of the end face coating of the LBO crystal > 99.8% @ 532 nm, and the optical damage threshold > 500 MW / cm 2 , to avoid fluctuations in the second harmonic output. The LBO crystal is placed in a copper bracket with a built-in heater, and the temperature of the bracket is set to 46°C.

[0116] Exemplarily, the parameters of the fourth focusing lens 432 and the third collimating lens 434 are specifically designed according to the frequency doubling crystal and actual requirements. The transmittance of the fourth focusing lens 432 > 99.9% @ 1064 nm, and the damage threshold > 15 J / cm 2 , the transmittance of the third collimating lens 434 > 99.9% @ 532 nm, and the damage threshold > 15 J / cm 2 . The 45° beam splitter is coated with a 532-nm reflective film, and the reflectivity > 99%.

[0117] Exemplarily, the second frequency doubling crystal 437 uses an LBO (lithium triborate) crystal, with a crystal size of 5×5×14 mm3 , the crystal cutting angle is θ = 90°, φ = 10.4°, the end face coating transmittance of the LBO crystal > 99.8% @ 532nm, and the optical damage threshold > 500MW / cm 2 , to avoid the fluctuation of the second harmonic output. Place the LBO crystal in a copper bracket with a built-in heater, and set the bracket temperature to 46°C. The second harmonic generation crystal 437 is placed with a 90° clockwise rotation relative to the first harmonic generation crystal 433.

[0118] For example, the parameters of the fifth focusing lens 436 and the fourth collimating lens 438 are specifically designed according to the harmonic generation crystal and actual requirements. The transmittance of the fifth focusing lens 436 > 99.9% @ 1064nm, and the damage threshold > 15J / cm 2 , the transmittance of the fourth collimating lens 438 > 99.9% @ 532nm, and the damage threshold > 15J / cm 2 . The seventh 45° beam splitter is coated with a reflection film for 532nm, and the reflectivity > 99%.

[0119] For another example, both the first window mirror 430a and the second window mirror 430b are used to block the influence of the external environment (such as air humidity, dust, etc.) on the laser cavity and the precision optical path. Their surfaces are coated with a high-transmission film for the 532nm wavelength (transmittance > 99%).

[0120] In the embodiment of the present application, through the settings of the fourth focusing lens 432, the first harmonic generation crystal 433, and the third collimating lens 434, the output of P-polarized green light can be realized. Through the settings of the fifth focusing lens 436, the second harmonic generation crystal 437, and the fourth collimating lens 438, the setting of S-polarized green light is realized. That is, through the settings of the embodiment of the present application, the switchable output of P-polarized green light and S-polarized green light is realized.

[0121] Exemplarily, the output module 400 further includes a first optical switch 431 and a second optical switch 435;

[0122] The first optical switch 431 is disposed between the polarization beam splitter prism 420 and the fourth focusing lens 432, and the second optical switch 435 is disposed between the polarization beam splitter prism 420 and the fifth focusing lens 436; wherein, the first optical switch 431 is configured to turn on or off the P-polarized channel, and the second optical switch 435 is configured to turn on or off the S-polarized channel.

[0123] In specific implementation, the first optical switch 431 and the second optical switch 435 have the same structure. The first optical switch 431 includes a first mirror 431a, a first servo, and a first optical trap 431b. The second optical switch 435 includes a second mirror 435a, a second servo, and a second optical trap 435b. Since the first optical switch 431 and the second optical switch 432 have the same structure and the same operating principle, the operating principles of the first optical switch 431 and the second optical switch 435 will be introduced below taking the first optical switch 431 as an example: The first servo is mechanically connected to the first mirror 431a. For example, the output shaft of the first servo may be directly connected to the bracket or rotating shaft of the first mirror 431a. When the first servo rotates under the control signal, it will drive the first mirror 431a to rotate around the axis, thereby changing the angle of the first mirror 431a, and thus realizing the switching of the optical path, that is, realizing the opening and closing of the optical path. In the "closed" state of the optical path, the first optical trap 431b is used to absorb the laser reflected by the first mirror 431a to avoid laser leakage or reflection back to the main optical path.

[0124] Exemplarily, both the first mirror 431a and the second mirror 431b can be set as 45° beam splitters.

[0125] In another implementation, a third mirror 440a and a third optical trap 440b are further provided between the third collimating lens 434 and the first beam splitter 610, and a fourth mirror 450a and a fourth optical trap 450b are further provided between the fourth collimating lens 438 and the fourth beam splitter 640. In specific implementation, both the third mirror 440a and the fourth mirror 450a are set as 45° dichroic mirrors, and the third mirror 440a and the fourth mirror 450a are coated with a film capable of filtering out the fundamental frequency light doped in the second harmonic light. That is, the films coated on the third mirror 440a and the fourth mirror 450a can highly reflect the fundamental frequency light (1064nm) and highly transmit the second harmonic light (532nm). The reflectivity of the fundamental frequency light is >99%, and the transmittance of the second harmonic light is >99%.

[0126] Since the third mirror 440a, the third optical trap 440b, the fourth mirror 450a, and the fourth optical trap 450b have the same structure and the same operating principle, the operating principles of the third mirror 440a and the third optical trap 440b will be introduced below taking the third mirror 440a and the third optical trap 440b as an example:

[0127] When the first window mirror 430a needs to output P-polarized green light, the seed laser is amplified by the first amplification module and the second amplification module to form the second laser. After the second laser is adjusted by the power adjustment component 410 and the polarization beam splitter prism 420 in sequence, it is frequency-doubled by the first frequency-doubling crystal 433. After frequency doubling, the third collimating mirror 434 collimates it to the third reflecting mirror 440a. The third reflecting mirror 440a has a high reflectivity for the fundamental frequency light, reflects the fundamental frequency light to the third optical trap 440b, and the third optical trap 440b absorbs the fundamental frequency light to prevent the leakage or reflection of the fundamental frequency light to the main optical path. The third reflecting mirror 440a has a high transmittance for the frequency-doubled laser. The frequency-doubled laser passes through the third reflecting mirror 440a, passes through the first beam splitter 610 and the second beam splitter 620 in sequence, and finally outputs through the first window mirror 430a.

[0128] In the embodiment of the present application, through the settings of the first optical switch 431 and the second optical switch 435, when the user needs to output P-polarized green light, the first optical switch 431 is turned on and the second optical switch 435 is turned off. When the user needs to output S-polarized green light, the first optical switch 431 is turned off and the second optical switch 435 is turned on. That is to say, when the user needs to output one of the polarized green lights, the output path of the other polarized green light is closed, thus avoiding the damage of the frequency-doubling crystal of the other path, playing a certain protective role for the frequency-doubling crystal, and improving the service life of the frequency-doubling crystal.

[0129] Exemplarily, the picosecond laser system includes a first beam splitter 610, a second beam splitter 620, a third beam splitter 630, a fourth beam splitter 640, and a fifth beam splitter 650;

[0130] The third power detection component includes a fourth photodetector 550 and a fifth photodetector 560, and the second pulse train detection component includes a second oscilloscope 580 and a third oscilloscope 590;

[0131] The first beam splitter 610 is arranged on the output side of the third collimating lens 434. The first pulse train detection component is arranged on the transmission side of the first beam splitter 610 to detect the number of pulse trains of the P-polarized green light. The second beam splitter 620 is arranged on the reflection side of the first beam splitter 610. The fourth photodetector 550 is arranged on the reflection side of the second beam splitter 620 to detect the P-polarized power of the P-polarized green light. The first window mirror 430a is arranged on the transmission side of the second beam splitter 620;

[0132] The third beam splitter 630 is disposed on the second output side of the polarization beam splitter 420, the fourth beam splitter 640 is disposed on the output side of the fourth collimating lens 438, the second oscilloscope 580 is disposed on the transmission side of the fourth beam splitter 640 for detecting the S-polarized power of the S-polarized green light, the fifth beam splitter 650 is disposed on the reflection side of the fourth beam splitter 640, and the fifth photodetector 560 is disposed on the reflection side of the fifth beam splitter 650 for detecting the polarization power of the S-polarized green light. The second window mirror 430b is disposed on the transmission side of the fifth beam splitter 650.

[0133] It should be noted that the first pulse train detection component can be set as the first oscilloscope 570.

[0134] In the embodiment of the present application, through the setting of the fourth photodetector 550, the P-polarized power of the P-polarized green light can be detected and fed back to the electronic control component 510, so that the electronic control component 510 adjusts the power adjustment component 410 according to the P-polarized power to output the P-polarized green light reaching the target P-polarized power. In the embodiment of the present application, through the setting of the fifth photodetector 560, the S-polarized power of the S-polarized green light can be detected and fed back to the electronic control component 510, so that the electronic control component 510 adjusts the power adjustment component 410 according to the S-polarized power to output the S-polarized green light reaching the S-polarized power.

[0135] Figure 2 For Figure 1 the structural schematic diagram of the first crystal component in Figure 3 For Figure 1 the structural schematic diagram of the second crystal component in

[0136] In some other examples, referring to Figure 2 and Figure 3 , the picosecond laser system includes a first beam splitting component, a second beam splitting component 800 and a third beam splitting component, the amplification module includes a first amplification module 200 and a second amplification module 300; the second power detection component includes a second photodetector 530 and a third photodetector 540;

[0137] The first beam splitting component is disposed on the output side of the seed source module 100, the first amplification module 200 is disposed on the transmission side of the first beam splitting component, and the first power detection component and the first pulse train detection component are disposed on the reflection side of the first beam splitting component;

[0138] The first amplification module 200 includes a first crystal component 210 and a first pump 250. The first pump 250 is configured to form a first pump light. The incident direction of the first pump light and the incident direction of the seed laser are oppositely arranged. The seed laser forms a first laser in the first crystal component 210 through pumping by the first pump light.

[0139] The second beam splitting component 800 is disposed on the output side of the first amplification module 200. The second amplification module 300 is disposed on the reflection side of the second beam splitting component 800. The second photodetector 530 is disposed on the transmission side of the second amplification module 300 to detect the laser power of the first laser.

[0140] The second amplification module 300 includes a second crystal component 310 and a second pump 350. The second pump 350 is configured to form a second pump light. The incident direction of the second pump light is set opposite to the incident direction of the first laser. The first laser is pumped by the second pump light in the second crystal component 310 to form an amplified laser.

[0141] The third beam splitting component is disposed on the output side of the second amplification module 300. The third photodetector 540 is disposed on the transmission side of the second beam splitting component 800 to detect the laser power of the amplified laser. The output module 400 is disposed on the reflection side of the third beam splitting component.

[0142] Exemplarily, the first beam splitting component includes a sixth beam splitter 710 and a seventh beam splitter 720. Among them, the sixth beam splitter 710 is disposed on the output side of the optical isolator. The first crystal component 210 is disposed on the transmission side of the sixth beam splitter 710. The seventh beam splitter 720 is disposed on the reflection side of the sixth beam splitter 710. The first power detection component is disposed on the transmission side of the seventh beam splitter 720. The first pulse train detection component is disposed on the reflection side of the seventh beam splitter 720.

[0143] In specific implementation, the sixth beam splitter 710 can be set as a sixth 45° beam splitter, and the seventh beam splitter 720 can be set as a seventh 45° beam splitter. The sixth beam splitter 710 is selected as a beam splitter with a splitting ratio of 99:1, that is, it has a transmittance of 99% and a reflectance of 1% for the 1064nm laser. The splitting ratio of the seventh beam splitter 720 is 1:1, that is, it has a transmittance of 50% and a reflectance of 50% for the 1064nm laser.

[0144] Exemplarily, the first power detection component is set as the first photodetector 520. The first photodetector 520 is used to convert the laser signal of the seed laser into an electrical signal and then transmit it to the electronic control component 510. The first pulse train detection component is set as an oscilloscope to monitor the number of pulse trains and the output waveform of the seed laser.

[0145] In some other examples, the first amplification module 200 further includes a first dichroic mirror 220, a first focusing lens 230, and a first collimating lens 240. Among them, the first crystal component 210, the first dichroic mirror 220, the first focusing lens 230, the first collimating lens 240, and the first pump 250 are coaxially disposed along the output path of the seed laser.

[0146] Exemplarily, the function of the first pump 250 is to generate pump light through a semiconductor laser, and the semiconductor laser can provide pump energy for the power amplification of the picosecond seed laser. The first pump 250 can adopt multiple wavelengths such as 808 nm and 878 nm, with a pump power of 60 W and a fiber core diameter of 100 μm. Compared with the 808 nm pump, the 878 nm pump has a lower quantum deficit and can significantly reduce the crystal thermal effect.

[0147] Exemplarily, the first focusing lens 230 and the first collimating lens 240 are used to shape the first pump light emitted by the first pump 250 to form a focused spot. The first focusing lens 230 and the second collimating lens 340 constitute a 4F optical system. Among them, the first collimating lens 240 is used to collimate the first pump light emitted by the first pump 250, and the first focusing lens 230 is used to focus the collimated first pump light. The diameter of the focused spot is related to the focal lengths of the two lenses, and the diameter of the focused spot is set as D2. The ratio of D1 to D2 is the filling factor (the ratio of the seed laser diameter to the first pump light diameter), and the filling factor largely determines the coupling and matching degree between the laser beam and the pump region. If it is too large or too small, it will exacerbate the thermal effect inside the crystal. In order to improve the amplification efficiency of the seed picosecond laser and, at the same time, ensure good beam quality, the filling factor can be designed to be 0.7 - 0.8.

[0148] The first dichroic mirror 220 is used to reflect the first laser emitted from the first crystal assembly 210 to the second amplification module 300. The first dichroic mirror is coated with a film that is highly transmissive to pump light and highly reflective to 1064 nm laser. The transmittance of the pump light is >98.5%, and the reflectivity for 1064 nm laser is >99%.

[0149] Exemplarily, the second beam splitting component 800 includes a second photo - isolator 810, a third focusing lens 820, and an eighth beam splitter 830. The seed laser is amplified by the first amplification module 200 to form the first laser. The first laser is reflected by the first dichroic mirror 220 to the second photo - isolator 810. After passing through the second photo - isolator 810, the first laser is focused by the second focusing lens and then reflected by the eighth beam splitter 830 and reflected to the second amplification module 300. Among them, a second photodetector 530 is arranged on the transmission side of the eighth beam splitter 830, and the second photodetector 530 is used to detect the laser power of the second laser.

[0150] Exemplarily, the diameter of the focused spot of the third focusing lens 820 for the first laser is set as D3. Among them, the selection of D3 needs to be comprehensively considered and designed according to the structures of the first amplification module 200 and the second amplification module 300.

[0151] In some other examples, the third beam splitting component includes a ninth beam splitter 910. The third photodetector 540 is disposed on the transmission side of the ninth beam splitter 910, and the output module 400 is disposed on the reflection side of the ninth beam splitter 910. The ninth beam splitter 910 is set as a ninth 45° beam splitter, and the beam splitting ratio can be set to 99:1, that is, the reflectivity is 99% and the transmittance is 1%.

[0152] In another implementation manner, the second amplification module further includes a second dichroic mirror 320, a second focusing lens 330, a second collimating lens 340, and a second pump 350;

[0153] The second crystal assembly is disposed on the reflection side of the second beam splitting component 800; the second crystal assembly, the second dichroic mirror 320, the second focusing lens 330, the second collimating lens 340, and the second pump 350 are coaxially disposed along the transmission path of the first laser;

[0154] The second dichroic mirror 320 is configured to transmit the second pump light generated by the second pump 350 to the second crystal assembly, and reflect the amplified laser output from the second crystal assembly to the output module 400;

[0155] The second focusing lens 330 and the second collimating lens 340 are configured to shape the second pump light and then inject it into the second crystal assembly through the second dichroic mirror 320.

[0156] For example, the second collimating lens 340 and the second focusing lens 330 form a 4F optical system.

[0157] Also for example, the second dichroic mirror 320 is coated with a film that is highly transmissive to the second pump light and highly reflective to the second laser (1064 nm laser). The transmittance of the second dichroic mirror 320 to the second pump light is greater than 98.5%, and the reflectivity to the second laser is greater than 99%.

[0158] Still for example, after the second pump light is collimated by the second collimating lens 340, it is focused by the second focusing lens 330 onto one of the second laser crystals 311 in the second crystal assembly, and then matches with the first laser emitted from the second beam splitting component 800 through the other second laser crystal 311.

[0159] Exemplarily, the second focusing lens 330 is used to focus the second pump light collimated by the second collimating lens 340. The diameter of the focused light spot is related to the focal lengths of the second focusing lens 330 and the second collimating lens 340. Let the diameter of the focused light spot be D4, and the ratio of the diameter of the focused light spot of the first laser, set as D3, to the focused light spot D4 of the collimated second pump 350 is also the filling factor. To improve the laser amplification efficiency and ensure good beam quality at the same time, the filling factor can be set to 0.85 - 0.95.

[0160] Exemplarily, the second crystal assembly is used to provide a gain medium for the laser power amplification of the first laser, and the second pump 350 is used to generate semiconductor laser to provide pump energy for the laser power amplification of the first laser.

[0161] In the embodiment of the present application, by oppositely arranging the incident direction of the first pump light and the incident direction of the seed laser in the first amplification module 200, a backward pump is formed in the first amplification module 200; in the embodiment of the present application, by oppositely arranging the incident direction of the second pump light and the incident direction of the first laser in the second amplification module 300, a backward pump is formed in the second amplification module 300. Through the setting of the backward pump in the embodiment of the present application, the pump light (including the first pump light and the second pump light) can be made to propagate in the opposite direction to the signal light (including the seed laser and the first laser). The pump light can still maintain a high intensity at the end of the gain medium, providing sufficient gain support for the signal light in the later stage of amplification, enabling the signal light to make full use of the remaining pump light energy during the process of gradual amplification, and significantly improving the gain utilization efficiency and power output capacity. Further, in the embodiment of the present application, compared with the double-end pump, the backward pump further simplifies the pump optical path design, reduces the requirements for optical devices and coupling structures, and improves the structural compactness of the picosecond laser system.

[0162] In some other examples, the first crystal assembly 210 includes a first laser crystal 211, a first heat sink 212, a first thermoelectric cooler 213, a first liquid-cooled radiator 214, and a first temperature sensor 215; two first heat sinks 212 are respectively arranged on both sides of the first laser crystal 211 to support the first laser crystal 211, the first thermoelectric cooler 213 is arranged on one side of one of the first heat sinks 212 to adjust the temperature of the first laser crystal 211, and the first liquid-cooled radiator 214 is arranged on one side of the first thermoelectric cooler 213 to dissipate heat from the first thermoelectric cooler 213; the first temperature sensor 215 is arranged on the first heat sink 212 to monitor the temperature of the first laser crystal 211 in real time;

[0163] The second crystal assembly 310 includes two second laser crystals 311, a second heat sink 312, a second thermoelectric cooler 313, a second liquid-cooled radiator 314, and a second temperature sensor 315; two second laser crystals 311 are arranged side by side; two second heat sinks 312 are respectively arranged on both sides of the second laser crystals 311 to support the second laser crystals 311, the second thermoelectric cooler 313 is arranged on one side of one of the second heat sinks 312 to adjust the temperature of the second laser crystals 311, and the second liquid-cooled radiator 314 is arranged on one side of the second thermoelectric cooler 313 to dissipate heat from the second thermoelectric cooler 313; the second temperature sensor 315 is arranged on the second heat sink 312 to monitor the temperature of the second laser crystals 311 in real time;

[0164] The first thermoelectric cooler 213, the first temperature sensor 215, the second thermoelectric cooler 313, and the second temperature sensor 315 are respectively connected to the electronic control component in a signal manner.

[0165] Exemplarily, both the first laser crystal 211 and the second laser crystal 311 can adopt Nd:YVO4 (neodymium-doped yttrium vanadate crystal) crystals, and the doping concentration of Nd 3+ is 0.1% - 0.5%, in a bonded or non-bonded form. Among them, the bonded form includes a single-end bonded crystal (Nd:YVO4 - YVO4) or a double-end bonded crystal (YVO4 - Nd:YVO4 - YVO4). The undoped YVO4 crystal functions as a heat sink, facilitating better heat dissipation of the crystal and reducing the thermal effect of the crystal. The geometric size of the first laser crystal 211 can be designed according to the actual amplification power requirements.

[0166] For example, both the first laser crystal 211 and the second laser crystal 311 are wrapped with indium foil.

[0167] Also for example, both the first heat sink 212 and the second heat sink 312 are set as copper heat sinks.

[0168] In the embodiments of the present application, through the settings of the first heat sink 212 and the second heat sink 312, on the one hand, it can support the second laser crystal 311 and the third laser crystal, and on the other hand, it can play a role in quickly conducting heat. In the embodiments of the present application, through the settings of the first temperature sensor 215 and the second temperature sensor 315, the real-time temperatures of the first laser crystal 211 and the second laser crystal 311 can be monitored in real time through the electronic control component 510, and according to the monitored real-time temperatures, through the first thermoelectric cooler 213 and the second thermoelectric cooler 313, the temperatures of the second laser crystal 311 and the third laser crystal can be respectively regulated to achieve precise temperature control of the second laser crystal 311.

[0169] In specific implementation, the laser system may further include a cooling module. The first liquid-cooled radiator 214 includes a first liquid inlet 214a and a first liquid outlet 214b. The first liquid inlet 214a and the first liquid outlet 214b are respectively connected to the cooling module, so that the first liquid-cooled radiator 214 can take away the heat on the surface of the first thermoelectric cooler 213 through the flow of the cooling liquid, so as to reduce the influence of temperature on the first laser crystal 211. While the cooling liquid in the first liquid-cooled radiator 214 takes away the surface temperature of the first thermoelectric cooler 213, the temperature of the cooling liquid rises. The cooling liquid with the increased temperature enters the cooling module for cooling and then enters the liquid-cooled radiator through the first liquid inlet 214a.

[0170] Further, the second liquid cooling radiator 314 includes a second liquid inlet 314a and a second liquid outlet 314b. The second liquid inlet 314a and the second liquid outlet 314b are respectively connected to the cooling module, so that the second liquid cooling radiator 314 takes away the heat on the surface of the second thermoelectric cooler 313 through the flow of the cooling liquid, thereby reducing the influence of temperature on the two second laser crystals 311. While the cooling liquid in the second liquid cooling radiator 314 takes away the surface temperature of the second thermoelectric cooler 313, the temperature of the cooling liquid rises. After the temperature of the cooling liquid rises, it enters the cooling module for cooling and then enters the liquid cooling radiator through the second liquid inlet 314a.

[0171] In the embodiment of the present application, through the settings of the first liquid cooling radiator 214 and the second liquid cooling radiator 314, the first thermoelectric cooler 213 and the second thermoelectric cooler 313 can be cooled, so as to avoid the interference of the first thermoelectric cooler 213 and the second thermoelectric cooler 313 on the temperatures of the first laser crystal 211 and the second laser crystal 311, and ensure the stable operation of the first thermoelectric cooler 213 and the second thermoelectric cooler 313.

[0172] Figure 4 It is the method flow of a control method for a green picosecond laser system provided by an embodiment of the present application Figure 1 。

[0173] Refer to Figure 4 , based on a green picosecond laser system, the embodiment of the present application further provides a control method for a green picosecond laser system, and the method includes the following steps:

[0174] S11: Receive the laser power of the seed laser detected by the first power detection component.

[0175] Among them, the seed laser is the laser signal output by the seed source module 100, and the laser power of the seed laser is the laser power detected by the first power detection component.

[0176] The electronic control component 510 receives the current signal of the seed laser output by the first photodetector 520, and amplifies the current signal to obtain the laser power of the seed laser.

[0177] S12: Determine whether the laser power of the seed laser is within the first preset power range.

[0178] The electronic control component 510 determines whether the laser power of the seed laser is within the first preset power range.

[0179] In specific implementation, the fluctuation setting range of the output power is usually within ±1% of the first preset power value.

[0180] S13: If the laser power of the seed laser is within the preset power range, turn on the amplification module to amplify the power of the seed laser to form amplified laser light.

[0181] In specific implementation, since the electronic control component 510 is electrically connected to the green picosecond laser system, that is, the electronic control component 510 provides power for the operation of the picosecond laser system, which means the electronic control component 510 provides power for the amplification module. When the electronic control component 510 determines that the laser power of the seed laser is within the first preset power range, it will turn on the amplification module.

[0182] It should be noted that when the laser power of the seed laser is not within the first preset power range, the electronic control component 510 directly cuts off the power supply of the green picosecond laser system.

[0183] S14: Receive the laser power of the amplified laser detected by the second power detection component;

[0184] Wherein, the laser power of the amplified laser is the laser power detected by the second power detection component.

[0185] S15: Determine whether the laser power of the amplified laser is within the second preset power range. If the laser power of the amplified laser is within the second preset power range, then perform any of the following steps according to the user instruction:

[0186] It should be noted that in specific implementation, the electronic control component receives an external control signal (i.e., the user instruction), and the electronic control component executes step A or step B according to the external control signal.

[0187] Figure 5 For Figure 4 the specific step diagram of S14 - S15.

[0188] In specific implementation, referring to Figure 5 , S14 - S15 specifically includes the following steps:

[0189] S14 - 1: Turn on the first amplification module 200;

[0190] S14 - 2: Receive the laser power of the first laser.

[0191] Wherein, the first laser is the laser signal output by the first amplification module 200, and the laser power of the first laser is the laser power detected by the second photodetector 530;

[0192] S14 - 3: Determine whether the laser power of the first laser is within the intermediate laser preset power range.

[0193] S14-4: If the laser power of the first laser is within the intermediate laser preset power range, turn on the second amplification module 300. The second amplification module 300 amplifies the power of the first laser to form amplified laser light.

[0194] In specific implementation, if the laser power of the first laser is not within the intermediate laser preset power range, the electronic control component 510 outputs a power adjustment signal to the first pump 250 to adjust the pumping energy of the first pump 250 until the laser power of the first laser can be within the intermediate laser preset range.

[0195] S14-5: Receive the laser power of the amplified laser light.

[0196] S15-6: Determine whether the laser power of the second laser is within the second preset power range. If the laser power of the amplified laser light is within the second preset power range, perform any of the following steps according to the user instruction:

[0197] Step A:

[0198] S16-1: Receive the number of pulse trains of the seed laser detected by the first pulse train detection component and the number of pulse trains of the P-polarized green light detected by the second pulse train detection component respectively.

[0199] S17-1: Determine whether the number of pulse trains of the seed laser and the number of pulse trains of the P-polarized green light are consistent. If they are consistent, receive the laser power of the P-polarized green light output by the third power detection component.

[0200] It should be noted that if the number of pulse trains of the seed laser and the number of pulse trains of the P-polarized green light are inconsistent, the electronic control component 510 directly turns off the power supply of the green picosecond laser system.

[0201] S18-1: Determine whether the laser power of the P-polarized green light is the first predetermined value. If it is not, output an adjustment signal to the power adjustment component; if it is, turn off the second optical switch 435 and output the P-polarized green light.

[0202] It should be noted that when the power adjustment component 410 receives the adjustment signal, the motor rotates according to the adjustment signal to adjust the angle of the half-wave plate so that the splitting ratio output by the polarization beam splitter prism 420 can be accurately controlled, so that the effective optical power entering the first frequency doubling crystal 433 is more stable, and further the laser power of the P-polarized green light reaches the first predetermined value.

[0203] Step B:

[0204] S16-2: Receive the number of pulse trains of the seed laser output by the first pulse train detection component and the number of pulse trains of the S-polarized green light output by the second pulse train detection component respectively.

[0205] S17-2: Determine whether the number of pulse trains of the seed laser is the same as that of the S-polarized green light. If they are the same, receive the laser power of the S-polarized green light output by the third power detection component.

[0206] It should be noted that if the number of pulse trains of the seed laser is not the same as that of the S-polarized green light, the electronic control component 510 directly shuts down the power supply of the green picosecond laser system.

[0207] S18-2: Determine whether the laser power of the S-polarized green light is the second predetermined value. If it is not, output an adjustment signal to the power adjustment component; if it is, turn off the first optical switch 431 and output the S-polarized green light.

[0208] It should be noted that when the power adjustment component 410 receives the adjustment signal, the motor rotates according to the adjustment signal to adjust the angle of the half-wave plate, so that the splitting ratio output by the polarization beam splitter prism 420 can be accurately controlled, so that the effective optical power entering the second frequency doubling crystal 437 is more stable, and further the laser power of the P-polarized green light reaches the first predetermined value.

[0209] In specific implementation, the motor uses micro-drive technology, and the rotation angle of the half-wave plate adjusted each time is set to 0.5°. If the rotation angle is greater than 0.5°, overshoot is likely to occur. If the rotation angle is less than 0.5°, the adjustment efficiency will be affected. Therefore, setting the rotation angle of the half-wave plate adjusted each time to 0.5° not only ensures the adjustment accuracy but also improves the adjustment efficiency.

[0210] Furthermore, after the picosecond laser system is turned on, both the first optical switch 431 and the second optical switch 432 are in the on state.

[0211] Furthermore, if the laser power of the amplified laser is not within the second preset power range, the electronic control component 510 outputs a power adjustment signal to the second pump 350 to adjust the pump energy of the second pump 350 until the laser power of the amplified laser can be within the intermediate laser preset range.

[0212] Based on the control method of the green picosecond laser system, users can adjust the number of pulse trains according to actual needs. Through the method of this application embodiment, the target laser output of 1 to 15 pulse trains can be achieved.

[0213] The embodiment of the present application provides a control method for a green picosecond laser system. In the embodiment of the present application, by respectively receiving the laser power of the seed laser and the laser power of the amplified laser, and judging the laser power of the seed laser and the laser power of the amplified laser one by one, the stability of the laser power output to the output module 400 can be ensured; further, when the user needs to output P-polarized green light with a laser power of a first predetermined value, the electronic control component 510 receives and judges the laser power of the P-polarized green light, and outputs an adjustment signal to the power adjustment component according to the laser power of the P-polarized green light to adjust the laser power of the P-polarized green light until the P-polarized green light of the first predetermined value is output; when the user needs to output S-polarized green light with a laser power of a second predetermined value, the electronic control component 510 receives and judges the laser power of the S-polarized green light, and outputs an adjustment signal to the power adjustment component according to the laser power of the S-polarized green light to adjust the laser power of the S-polarized green light until the S-polarized green light of the second predetermined value is output; that is, through the setting of the present application, the P-polarized green light and the S-polarized green light in the green picosecond laser system can be switched and output according to the preset power, which is convenient for the user to use and improves the processing efficiency. Further, in the embodiment of the present application, by receiving and judging the number of pulse trains of the seed laser and the number of pulse trains of the P-polarized green light / the number of pulse trains of the S-polarized green light, the polarized light of the P-polarized green light / the S-polarized green light outputting a predetermined number of pulses can be ensured, so that the polarized light of different pulse trains can be output according to the user's needs, which not only meets the requirements for high-power multi-pulses, but also provides a more flexible and diverse laser output mode, facilitating the user's use.

[0214] Figure 6 The method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 2 。

[0215] Referring to Figure 6 , the control method of the green picosecond laser system further includes the following steps:

[0216] S21: Receive the crystal temperature of the first laser crystal 211 output by the first temperature sensor 215;

[0217] S22: Judge whether the crystal temperature of the first laser crystal 211 is within the first temperature range;

[0218] S23: If the crystal temperature of the first laser crystal 211 is within the first temperature range, start the PID algorithm, and use the first thermoelectric cooler 213 to adjust the temperature of the first laser crystal 211 to the first optimal temperature, so as to amplify the seed laser within the optimal temperature range in the first amplification module 200 to form the first laser;

[0219] S24: Receive the crystal temperature of the second laser crystal 311 output by the second temperature sensor 315;

[0220] S25: Determine whether the crystal temperature of the second laser crystal 311 is within the second temperature range;

[0221] S26: If the crystal temperature of the second laser crystal 311 is within the second temperature range, start the PID algorithm, and use the second thermoelectric cooler 313 to adjust the temperature of the second laser crystal 311 to the second optimal temperature, so as to amplify the first laser within the optimal temperature range in the second amplification module 300 to form an amplified laser.

[0222] Taking S23 as an example, the specific method of using the PID control algorithm and the first thermoelectric cooler 213 to adjust the temperature of the first laser crystal 211 to the first optimal temperature is explained.

[0223] The electronic control component 510 collects the current temperature T of the first laser crystal 211 at each discrete moment k measured (k).

[0224] Set the target temperature to T set Then the temperature error e(k) is:

[0225] e(k) = T set -T measured (k)

[0226] A positive error indicates that the current temperature is lower than the target value and heating is required; a negative error indicates that the temperature is higher than the target value and cooling is required.

[0227] To avoid excessive integral accumulation (integral saturation) in the traditional positional PID and system jitter caused by frequent switching of the current at both ends of the TEC, the incremental PID method is used to calculate the change amount Δu(k) of the control signal. The operation formula is as follows:

[0228]

[0229] Among them, K p is the proportional gain, responsible for responding to the error change; K i is the integral gain, participating in the product of the current cycle error and the sampling interval Δt, helping to eliminate the steady-state error; K d is the differential gain, predicting the error change through the second-order difference of the current and the previous two sampling errors; Δt is the sampling time interval; e(k - 1) and e(k - 2) are the temperature errors at the previous moment and the moment before the previous moment respectively.

[0230] This calculation method is only based on the current sampled data and the recent error change, thus naturally avoiding the saturation problem caused by excessive accumulation of the integral term, and making the control output update amplitude smaller when the temperature change is small, which helps to reduce system jitter.

[0231] The control output is calculated by the incremental update method:

[0232] u(k) = u(k - 1)+Δu(k)

[0233] Where u(k) is the control signal of the k-th cycle, and its value corresponds to the reference value for adjusting the driving current of the first thermoelectric cooler 213. In practical applications, this output signal can be further converted to limit the step size of each adjustment (for example, the corresponding temperature change does not exceed 0.01 °C) to ensure a smooth and stable temperature control process.

[0234] In specific implementation, taking the target temperature T of the first laser crystal 211 set = 20.00 °C; the current temperature T of the first laser crystal 211611 measured by the first temperature sensor 215 measured (k) = 19.98 °C; Δt = 0.05 s; e(k - 1) = 0.03 °C; e(k - 2) = 0.025 °C; PID parameters: K p = 2.0, K i = 0.5, K d = 1.0; u(k - 1) = 0.50.

[0235] Then the error is calculated as follows:

[0236] e(k) = 20.00 °C - 19.98 °C = 0.02 °C

[0237] The proportional part is calculated as follows:

[0238] Δu P = 2.0×(0.02 - 0.03) = -0.02

[0239] The integral part is calculated as follows:

[0240] Δu I = 0.5×0.02×0.05 = 0.0005

[0241] The derivative part is calculated as follows:

[0242]

[0243] Calculating the numerator gives: 0.02 - 0.06 + 0.025 = -0.015, and then:

[0244]

[0245] The total increment and the control signal update are calculated as follows:

[0246] Δu(k) = -0.02 + 0.0005 - 0.3 = -0.3195

[0247] u(k) = 0.50 + (-0.3195) = 0.1805

[0248] That is to say, the electronic control component 510 only needs to drive the driving current of the first thermoelectric cooler 213 to increase by 0.1805 °C, which provides a basis for adjusting the driving current of the first thermoelectric cooler 213, so that the temperature gradually approaches the target temperature.

[0249] In addition, it should be noted that in S26, through the PID control algorithm, the second thermoelectric cooler 313 is used to adjust the second laser crystal 311 to the second optimal temperature. Refer to the above method, which will not be elaborated here.

[0250] Of course, in specific implementation, the electronic control component 510 can also adjust the working currents of the first pump 250 and the second pump 350 through the PID control algorithm. Refer to the above method, which will not be elaborated here.

[0251] Figure 7 This is the method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 3 .

[0252] In another implementation manner, referring to Figure 7 , an embodiment of the present application also provides a control method for a green picosecond laser system, wherein the control method includes the following steps:

[0253] S31: Receive the first power output by the first power detection component;

[0254] S32: Calculate the number of seed laser pulses according to the first power based on the preset power and pulse number correspondence relationship;

[0255] It should be noted that the preset power and pulse number correspondence relationship is established based on existing experimental data. For example, in a specific experiment, the experimental device includes a picosecond seed source 110 and a photodetector. By adjusting the acousto-optic modulator of the picosecond seed source 110 to output different numbers of pulses, and recording the corresponding power at different numbers of pulses through the photodetector. Among them, the correspondence relationship between the number of pulses and the output power is shown in Table 1.

[0256] Table 1 Correspondence relationship table between the number of pulses and the output power

[0257]

[0258]

[0259] According to the data measured in Table 1, a linear regression fitting is performed. Among them, the fitting curve is shown in Figure y.

[0260] Through linear regression fitting, the mathematical relationship between the output power and the number of pulses is obtained as follows:

[0261] P = 4.21×N + 10.63

[0262] Among them, P represents the output power, and N represents the number of pulses.

[0263] Figure 8 It is the fitting curve graph of the output power and the number of pulses.

[0264] Refer to Figure 8 , Figure 8 The data point a1 marked in is the data point where the output power is 10 when the number of pulses is 1; the data point a2 is the data point where the output power is 17.6 when the number of pulses is 2; the data point a3 is the data point where the output power is 23.9 when the number of pulses is 3; the data point a4 is the data point where the output power is 28.9 when the number of pulses is 4; the data point a5 is the data point where the output power is 33.4 when the number of pulses is 5; the data point a2 is the data point where the output power is 37.8 when the number of pulses is 6; the data point a7 is the data point where the output power is 41.6 when the number of pulses is 7; the data point a8 is the data point where the output power is 45.2 when the number of pulses is 8; the data point a9 is the data point where the output power is 49.6 when the number of pulses is 8; the data point a10 is the data point where the output power is 53.5 when the number of pulses is 10; the data point a15 is the data point where the output power is 70.1 when the number of pulses is 15.

[0265] Curve A is the curve fitted according to the data points a1 - a15, that is, the curve of the change of the output power with the number of pulses.

[0266] S33: If the number of seed laser pulses is not within the preset number interval, then turn off the picosecond laser system.

[0267] It should be noted that in specific implementation, the number of seed laser pulses obtained by calculation may be a decimal. At this time, the number of seed pulses needs to be corrected by rounding. If the corrected number of seed laser pulses is not within the preset number interval, then turn off the picosecond laser system.

[0268] Of course, if the corrected number of seed laser pulses is within the preset number interval, then the picosecond laser system can continue to operate.

[0269] To verify the actual application effect of a picosecond laser system, a green picosecond laser system was built for testing.

[0270] The picosecond seed source 110 is a picosecond pulsed laser using SESAM (Semiconductor Saturable Absorber Mirror) mode-locking technology. The central wavelength of the output pulse is 1064 nm, the single-pulse energy is 60 nJ, and the repetition frequency is 1 MHz.

[0271] The first laser crystal 211 is a rod-shaped YVO4 / Nd:YVO4 (yttrium vanadate) composite crystal. The size of the first laser crystal 211 is set to 3×3×(1.5 + 19.5) mm 3 , where Nd 3+ The doping concentration is 0.15%. The first laser crystal 211 is pumped by a first pump 250 with a wavelength of 878 nm, a core diameter of 200 μm, and an output power of 60 W. Two second laser crystals 311 are rod-shaped YVO4 / Nd:YVO4 (yttrium vanadate) composite crystals, with a doping concentration of 0.15 at% in atomic percentage, and the size is 3×3×(1.5 + 19.5) mm 3 . To obtain a higher-power laser output, the output power of the second pump 350 is set to 110 W, the core diameter is 400 μm, and the pump wavelength of the second pump 350 is 878 nm.

[0272] The power adjustment component 410 is used to rotate and change the energy ratio of the laser in the two linear polarization directions of P and S. The center wavelength of the half-wave plate coating is 1064 nm, and the damage threshold > 2 GW / cm 2 . The polarization beam splitter prism 420 splits the beam modulated by the power adjustment component 410 into P-polarized light and S-polarized light. The first frequency doubling crystal 433 receives the P-polarized light, and the P-polarized light generates second harmonic laser of 532 nm through the first frequency doubling crystal 433. The first frequency doubling crystal 433 uses an LBO (lithium triborate) crystal, with a crystal size of 5×5×14 mm 3 , the crystal cut angle is θ = 90°, φ = 10.4°, and the transmittance of the end face coating of the LBO crystal > 99.8% @ 532 nm. The second frequency doubling crystal 437 receives the S-polarized light, and the S-polarized light generates second harmonic laser of 532 nm through the second frequency doubling crystal 437. The second frequency doubling crystal 437 uses an LBO (lithium triborate) crystal, with a crystal size of 5×5×14 mm 3 , the crystal cut angle is θ = 90°, φ = 10.4°, and the transmittance of the end face coating of the LBO crystal > 99.8% @ 532 nm. The second frequency doubling crystal 437 is placed clockwise 90° relative to the first frequency doubling crystal 433.

[0273] The frequency-doubled light polarization-switchable laser system provided in this embodiment can achieve the output of green lasers with different polarizations. Taking the output green laser as P-polarized green light as an example for illustration.

[0274] Figure 9 It is a wavelength data graph of the P-polarized green light output.

[0275] For example, by finely adjusting the power adjustment component 410 and the polarization beam splitter prism 420, the laser polarization state is adjusted to P-polarized green light, and the central wavelength of the laser is measured to be 532.17 nm using a spectral analyzer. It can be referred to Figure 9 , Figure 9 In which curve D is the graph of the normalized intensity changing with the wavelength. It should be noted that Figure 9 The unit a.u. of the normalized intensity in

[0276] Figure 10 It is a pulse width data graph of the P-polarized green light output.

[0277] For example, by finely adjusting the power adjustment component 410 and the polarization beam splitter prism 420, the laser polarization state is adjusted to P-polarized green light, and the picosecond pulse width is measured to be 10.18 ps using an autocorrelator for autocorrelation testing. Refer to Figure 10 , in Figure 10 Curve E is the fitting graph of the normalized intensity changing with time, and curve E is the graph of the normalized intensity measured by the autocorrelation instrument changing with time. It should be noted that Figure 10 The unit a.u. of the normalized intensity in

[0278] Figure 11 It is a graph of the output power and stability of the P-polarized green light.

[0279] For example, by finely adjusting the power adjustment component 410 and the polarization beam splitter prism 420, the laser polarization state is adjusted to P-polarized green light, and the maximum average power of the 532 nm green laser in the P-polarized state is measured to be 22.7 W using a power meter, and the power stability is continuously recorded for 4 hours at a step of 0.3 s / single time to be 0.95% rms. Refer to Figure 11 , curve F is the graph of the output power changing with time, and in Figure 11 it shows that the power stability calculated by the power meter is less than 0.95% rms.

[0280] Next, taking the output green laser as P-polarized green light as an example for illustration again.

[0281] Figure 12 It is a graph of the output power and stability of the S-polarized green light.

[0282] For example, by fine-tuning the power adjustment component 410 and the polarization beam splitter prism 420, the polarization state of the laser is adjusted to S-polarized green light. Using a power meter, the maximum average power of the 532 nm green laser in the S-polarized state is measured to be 22.2 W, and the power stability is continuously recorded at 1.02% rms for 4 hours with a step of 0.3 s / single shot. Refer to Figure 12 , curve G is the graph of the output power versus time, and Figure 12 shows that the power stability calculated by the power meter is less than 1.02% rms.

[0283] Figure 13 is the 3-pulse data graph of the target laser; Figure 14 is the 9-pulse data graph of the target laser.

[0284] Using a digital storage oscilloscope, the laser sequence in the pulse train mode is tested. Refer to Figure 13 , curve M is the graph of the output voltage of the seed laser versus time. From curve M, it can be seen that the target laser outputs 3 pulses. Refer to Figure 14 , curve N in is the graph of the output voltage of the target laser versus time. From curve N, it can be seen that the seed laser outputs 9 pulses.

[0285] It should be noted that the target laser mentioned here can be P-polarized green light or S-polarized green light.

[0286] It is easy to understand that those skilled in the art can combine, split, and recombine the embodiments of the present application based on several embodiments provided in the present application to obtain other embodiments, and these embodiments do not exceed the protection scope of the present application.

[0287] The above specific implementation manners further elaborate on the purpose, technical solutions, and beneficial effects of the embodiments of the present application. It should be understood that the above are only the specific implementation manners of the embodiments of the present application and are not used to limit the protection scope of the embodiments of the present application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solutions of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.

Claims

1. A control method for a green picosecond laser system, characterized in that, The method includes the following steps: Receiving the laser power of the seed laser detected by the first power detection component; wherein, the seed laser is a laser signal output by the seed source module; Judging whether the laser power of the seed laser is within a first preset power range; If the laser power of the seed laser is within the preset power range, then turn on the amplification module to amplify the power of the seed laser to form amplified laser; Receiving the laser power of the amplified laser detected by the second power detection component; Judging whether the laser power of the amplified laser is within a second preset power range. If the laser power of the amplified laser is within the second preset power range, then perform any of the following steps according to the user instruction; Receiving respectively the number of pulse trains of the seed laser detected by the first pulse train detection component and the number of pulse trains of the P-polarized green light detected by the second pulse train detection component; Judging whether the number of pulse trains of the seed laser is consistent with the number of pulse trains of the P-polarized green light. If they are consistent, then receive the laser power of the P-polarized green light output by the third power detection component; Judging whether the laser power of the P-polarized green light is a first predetermined value. If not, then output an adjustment signal to the power adjustment component; Or, receiving respectively the number of pulse trains of the seed laser output by the first pulse train detection component and the number of pulse trains of the S-polarized green light output by the second pulse train detection component; Judging whether the number of pulse trains of the seed laser is consistent with the number of pulse trains of the S-polarized green light. If they are consistent, then receive the laser power of the S-polarized green light output by the third power detection component; Judging whether the laser power of the S-polarized green light is a second predetermined value. If not, then output an adjustment signal to the power adjustment component.

2. The control method of a green picosecond laser system according to claim 1, characterized in that, The step of judging whether the laser power of the P-polarized green light is a first predetermined value. If not, then output an adjustment signal to the power adjustment component; specifically includes the following steps: Judging whether the laser power of the P-polarized green light is a first predetermined value. If not, then output an adjustment signal to the power adjustment component; if so, then turn off the second optical switch and output the P-polarized green light; The step of judging whether the laser power of the S-polarized green light is a second predetermined value. If not, then output an adjustment signal to the power adjustment component; specifically includes the following steps: Judging whether the laser power of the S-polarized green light is a second predetermined value. If not, then output an adjustment signal to the power adjustment component; if so, then turn off the first optical switch and output the S-polarized green light.

3. The control method of a green picosecond laser system according to claim 1, characterized in that, The step of receiving the laser power of the amplified laser detected by the second power detection component; Judging whether the laser power of the amplified laser is within a second preset power range; specifically includes the following steps: Receiving the laser power of the first laser; wherein, the first laser is a laser signal output by the first amplification module, and the laser power of the first laser is the laser power detected by the second photodetector; Judging whether the laser power of the first laser is within the intermediate laser preset power range; If the laser power of the first laser is within the intermediate laser preset power range, the second amplification module is turned on, and the second amplification module amplifies the power of the first laser to form amplified laser; Receive the laser power of the amplified laser; Determine whether the laser power of the second laser is within the second preset power range.

4. The control method of a green picosecond laser system according to claim 3, characterized in that, The control method includes: Receive the crystal temperature of the first laser crystal output by the first temperature sensor; Determine whether the crystal temperature of the first laser crystal is within the first temperature range; If the crystal temperature of the first laser crystal is within the first temperature range, start the PID algorithm, and use the first thermoelectric cooler to adjust the temperature of the first laser crystal to the first optimal temperature, so as to amplify the seed laser within the optimal temperature range in the first amplification module to form the first laser; Receive the crystal temperature of the second laser crystal output by the second temperature sensor; Determine whether the crystal temperature of the second laser crystal is within the second temperature range; If the crystal temperature of the second laser crystal is within the second temperature range, start the PID algorithm, and use the second thermoelectric cooler to adjust the temperature of the second laser crystal to the second optimal temperature, so as to amplify the first laser within the optimal temperature range in the second amplification module to form amplified laser.

5. A green picosecond laser system, characterized in that, The green picosecond laser system adopts the control method of a green picosecond laser system according to any one of claims 1-4, and the picosecond laser system includes: a seed source module, an amplification module, an output module, and an electronic control module; The electronic control module includes an electronic control component and a first power detection component, a second power detection component, a third power detection component, a first pulse train detection component, and a second pulse train detection component that are respectively signal-connected to the electronic control component; the electronic control component is further configured to provide power to the picosecond laser system; The seed source module is used to generate seed laser; the first power detection component and the first pulse train detection component are arranged downstream of the optical path of the seed source module; the first power detection component is used to detect the laser power of the seed laser; the first pulse train detection component is used to detect the number of pulses of the seed laser; The amplification module is arranged downstream of the optical path of the seed source module, and the amplification module is used to amplify the power of the seed laser to form amplified laser; the output module and the second power detection component are both arranged downstream of the optical path of the amplification module; the second power detection component is used to detect the laser power of the amplified laser; The output module is arranged downstream of the optical path of the amplification module. The output module includes a power adjustment component and a switchable output channel arranged in sequence along the output optical path of the amplified laser. The switchable output channel is provided with a frequency doubling crystal. The power adjustment component is configured to modulate the laser power of the amplified laser to a predetermined power value, and then output P-polarized green light or S-polarized green light after frequency doubling by the frequency doubling crystal of the switchable output channel. The third power detection component is respectively arranged downstream of the optical path of the frequency doubling crystal to detect the laser power of the P-polarized green light or the laser power of the S-polarized green light. The second pulse train detection component is arranged downstream of the optical path of the frequency doubling crystal to detect the number of pulse trains of the P-polarized green light or the number of pulse trains of the S-polarized green light. The electronic control component is configured to determine whether the laser power of the P-polarized green light is a first predetermined value when the laser power of the seed laser and the laser power of the amplified laser are both within a preset power range and the number of pulse trains of the seed laser is the same as the number of pulse trains of the P-polarized green light. Or, the electronic control module is configured to determine whether the laser power of the S-polarized green light is a second predetermined value when the laser power of the seed laser and the laser power of the amplified laser are both within a preset power range and the number of pulse trains of the seed laser is the same as the number of pulses of the S-polarized green light. If the laser power of the P-polarized green light is not the first predetermined value or the laser power of the S-polarized green light is not the second predetermined value, an adjustment signal is output to the power adjustment component.

6. The green picosecond laser system according to claim 5, characterized in that, The output module further includes a polarization beam splitter prism. The switchable output channel includes a fourth focusing lens, a first frequency doubling crystal, a third collimating lens, a first window mirror, a fifth focusing lens, a second frequency doubling crystal, a fourth collimating lens, and a second window mirror. The polarization beam splitter prism is arranged on the output side of the power adjustment component. The fourth focusing lens is arranged on the first output side of the polarization beam splitter prism to output a first target laser. The fourth focusing lens, the first frequency doubling crystal, the third collimating lens, and the first window mirror are arranged along the output path of the first target laser. The fourth focusing lens is configured to focus the first target laser onto the first frequency doubling crystal. The first frequency doubling crystal is configured to convert the first target laser into P-polarized frequency-doubled laser, which is then collimated by the third collimating lens and output through the first window mirror. The fifth focusing lens is arranged on the second output side of the polarization beam splitter prism to output a second target laser. The fifth focusing lens, the second frequency doubling crystal, the fourth collimating lens, and the second window mirror are arranged along the output path of the second target laser. The fifth focusing lens is configured to focus the second target laser onto the second frequency doubling crystal. The second frequency doubling crystal is configured to convert the second target laser into S-polarized frequency-doubled laser, which is then collimated by the fourth collimating lens and output through the second window mirror.

7. A green picosecond laser system according to claim 6, characterized in that, The output module further includes a first optical switch and a second optical switch. The first optical switch is disposed between the polarization beam splitter prism and the fourth focusing lens, and the second optical switch is disposed between the polarization beam splitter prism and the fifth focusing lens; wherein, the first optical switch is configured to turn on or off the P polarization channel, and the second optical switch is configured to turn on or off the S polarization channel.

8. A green picosecond laser system according to claim 6, wherein, The picosecond laser system includes a first beam splitter, a second beam splitter, a third beam splitter, a fourth beam splitter, and a fifth beam splitter; The third power detection component includes a fourth photodetector and a fifth photodetector, and the second pulse train detection component includes a second oscilloscope and a third oscilloscope; The first beam splitter is disposed on the output side of the third collimating lens. The first pulse train detection component is disposed on the transmission side of the first beam splitter to detect the number of pulse trains of the P-polarized green light. The second beam splitter is disposed on the reflection side of the first beam splitter. The fourth photodetector is disposed on the reflection side of the second beam splitter to detect the P-polarized power of the P-polarized green light. The first window mirror is disposed on the transmission side of the second beam splitter; The third beam splitter is disposed on the second output side of the polarization beam splitter prism. The fourth beam splitter is disposed on the output side of the fourth collimating lens. The second oscilloscope is disposed on the transmission side of the fourth beam splitter to detect the S-polarized power of the S-polarized green light. The fifth beam splitter is disposed on the reflection side of the fourth beam splitter. The fifth photodetector is disposed on the reflection side of the fifth beam splitter to detect the polarization power of the S-polarized green light. The second window mirror is disposed on the transmission side of the fifth beam splitter.

9. The green picosecond laser system according to claim 8, wherein, The picosecond laser system includes a first beam splitting component, a second beam splitting component, and a third beam splitting component. The amplification module includes a first amplification module and a second amplification module; the second power detection component includes a second photodetector and a third photodetector; The first beam splitting component is disposed on the output side of the seed source module. The first amplification module is disposed on the transmission side of the first beam splitting component. The first power detection component and the first pulse train detection component are disposed on the reflection side of the first beam splitting component; The first amplification module includes a first crystal component and a first pump. The first pump is configured to form a first pump light. The incident direction of the first pump light is opposite to the incident direction of the seed laser. The seed laser is pumped by the first pump light in the first crystal component to form a first laser; The second beam splitting component is disposed on the output side of the first amplification module. The second amplification module is disposed on the reflection side of the second beam splitting component. The second photodetector is disposed on the transmission side of the second amplification module to detect the laser power of the first laser; The second amplification module includes a second crystal component and a second pump. The second pump is configured to form a second pump light. The incident direction of the second pump light is opposite to the incident direction of the first laser. The first laser is pumped by the second pump light in the second crystal component to form the amplified laser; The third beam splitting component is disposed on the output side of the second amplification module. The third photodetector is disposed on the transmission side of the second beam splitting component to detect the laser power of the amplified laser. The output module is disposed on the reflection side of the third beam splitting component.

10. A green picosecond laser system according to claim 9, characterized in that, The first crystal component includes a first laser crystal, a first heat sink, a first thermoelectric cooler, a first liquid-cooled radiator, and a first temperature sensor. The two first heat sinks are respectively disposed on both sides of the first laser crystal to support the first laser crystal. The first thermoelectric cooler is disposed on one side of one of the first heat sinks to adjust the temperature of the first laser crystal. The first liquid-cooled radiator is disposed on one side of the first thermoelectric cooler to dissipate heat from the first thermoelectric cooler. The first temperature sensor is disposed on the first heat sink to monitor the temperature of the first laser crystal in real time. The second crystal component includes a second laser crystal, a second heat sink, a second thermoelectric cooler, a second liquid-cooled radiator, and a second temperature sensor. There are two second laser crystals, and the two second laser crystals are arranged in parallel. The two second heat sinks are respectively disposed on both sides of the second laser crystal to support the second laser crystal. The second thermoelectric cooler is disposed on one side of one of the second heat sinks to adjust the temperature of the second laser crystal. The second liquid-cooled radiator is disposed on one side of the second thermoelectric cooler to dissipate heat from the second thermoelectric cooler. The second temperature sensor is disposed on the second heat sink to monitor the temperature of the second laser crystal in real time. The first thermoelectric cooler, the first temperature sensor, the second thermoelectric cooler, and the second temperature sensor are respectively connected to the electronic control component in signal.

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