A picosecond laser system and its control method

Abstract

An embodiment of the present application provides a picosecond laser system and its control method, which relates to the field of ultrafast laser technology and includes the following steps: receiving the first power output by the first power detection component; determining whether the first power is within the first preset power range; if the first power is within the first preset power range, turning on the first amplification module to perform first-stage amplification on the seed laser to form the first laser; receiving the second power output by the second power detection component; determining whether the second power is within the second preset power range; if the second power is within the second preset power range, turning on the second amplification module; receiving the crystal temperature of the double-crystal series connection component output by the temperature control component; determining whether the crystal temperature is within the preset temperature range; if the crystal temperature is within the preset temperature range, adjusting the crystal temperature to the optimal temperature control range to amplify the first laser to form the second laser, and modulating it through the output module to output the target laser.

Description

Technical Field

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

[0002] In the field of ultrafast laser technology, high-power picosecond lasers are widely used in many fields such as aerospace, biomedicine, transportation equipment, and 3C components due to their characteristics of narrow pulse width, high peak power, and small thermal influence area on materials. Compared with traditional continuous lasers and nanosecond lasers, picosecond laser processing has significant advantages such as high processing accuracy, small thermal influence area, and wide material applicability, showing broad application prospects.

[0003] In related technologies, high-power picosecond lasers are usually obtained by the master oscillator power amplification method using a picosecond laser system. The output power of the seed source of high-power picosecond lasers is relatively low, so a high-gain amplifier is required to achieve power improvement. Common solid-state laser amplifiers include regenerative amplifiers and traveling-wave amplifiers, etc. The advantage of a regenerative amplifier is high gain and the ability to obtain large-energy pulse output, but its system structure is complex and the cost is too high. A traveling-wave amplifier has the advantages of simple structure and low manufacturing cost, and can provide high power and high single-pulse energy output, but the gain of single-stage amplification is small, and usually, the number of amplification stages needs to be increased to obtain higher power. However, the setting of solid-state laser amplifiers will not only increase the volume of the picosecond laser system, but also introduce more optical elements due to multi-stage amplification, increasing the complexity and cost of the system. Taking a bulk crystal traveling-wave amplifier as an example, if the number of amplification stages is reduced to reduce the system volume or higher power is obtained, the pump power of each stage needs to be increased.

[0004] However, increasing the pump power of each stage will cause a significant increase in the thermal power consumption and thermal deposition inside the laser gain medium, which will in turn cause thermal effects such as birefringence and thermal lensing. These effects will not only reduce the overall efficiency of the laser, but also deteriorate the beam quality, affecting the performance and stability of the laser system. Summary of the Invention

[0005] The embodiments of the present application provide a picosecond laser system and a control method thereof to solve the problem that in related technologies, increasing the pump power of each stage will cause a significant increase in the thermal power consumption and thermal deposition inside the laser gain medium, which will in turn cause thermal effects such as birefringence and thermal lensing. These effects will not only reduce the overall efficiency of the laser, but also deteriorate the beam quality, affecting the performance and stability of the laser system.

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

[0007] Receiving a first power output by a first power detection component; wherein, the first power detection component is used to detect the first power of the seed laser;

[0008] Determine whether the first power is within the first preset power range;

[0009] If the first power is within the first preset power range, turn on the first amplification module to amplify the seed laser to form the first laser, and in the first amplification module, the incident path of the seed laser and the output path of the first laser are off-axis arranged;

[0010] Receive the second power output by the second power detection component; wherein, the second power detection component is used to detect the second power of the first laser;

[0011] Determine whether the second power is within the second preset power range;

[0012] If the second power is within the second preset power range, turn on the second amplification module to amplify the first laser to form the second laser; wherein, the second amplification module includes a temperature control component and a double crystal series connection component;

[0013] Receive the third power output by the third power detection component and the beam quality parameter output by the beam quality detection component, and obtain the optimal temperature value of the double crystal series connection component according to the third power and the beam quality parameter; wherein, the third power detection component is used to detect the third power of the second laser, and the beam quality detection component is used to detect the beam quality of the second laser;

[0014] Receive the crystal temperature of the double crystal series connection component output by the temperature control component;

[0015] Determine whether the crystal temperature is within the preset temperature range;

[0016] If the crystal temperature is within the preset temperature range, start the PID control algorithm to adjust the crystal temperature to the optimal temperature value, so that when the crystal temperature of the double crystal series connection component is at the optimal temperature value, the first laser is amplified to form the second laser, and after being modulated by the output module, the target laser is output.

[0017] In a feasible implementation manner, determine whether the crystal temperature is within the preset temperature range;

[0018] If the crystal temperature is within the preset temperature range, start the PID control algorithm to adjust the crystal temperature to the optimal temperature value, so that when the crystal temperature of the double crystal series connection component is at the optimal temperature value, the first laser is amplified to form the second laser, and after being modulated by the output module, the target laser is output, which specifically includes the following steps:

[0019] Receive the crystal temperature of the second laser crystal output by the first temperature control component;

[0020] Determine whether the temperature of the second laser crystal is within the first preset temperature range;

[0021] If the temperature of the second laser crystal is within the first preset temperature range, start the PID control algorithm and use the first temperature control component to adjust the temperature of the second laser crystal to the first optimal temperature;

[0022] Receive the crystal temperature of the third laser crystal output by the second temperature control component;

[0023] Determine whether the temperature of the third laser crystal is within the second preset temperature range;

[0024] If the temperature of the third laser crystal is within the second preset temperature range, start the PID control algorithm and use the second temperature control component to adjust the temperature of the third laser crystal to the second optimal temperature, so that when the crystal temperature of the double-crystal series connection component is at the optimal temperature value, the first laser is amplified to form the second laser, and after being modulated by the output module, the target laser is output.

[0025] In a feasible implementation manner, the steps of receiving the third power output by the third power detection component and the beam quality parameter output by the beam quality detection component, and obtaining the optimal temperature value of the double-crystal series connection component according to the third power and the beam quality parameter specifically include:

[0026] Adjust the temperature of the third laser crystal to the first temperature fixed value by using the second temperature control component;

[0027] Fix the temperature of the third laser crystal to the first temperature fixed value, and use the first temperature control component to gradually adjust the temperature of the second laser crystal within the first temperature range according to the first preset step size;

[0028] Receive the first beam quality parameter of the second laser crystal at each temperature value, and obtain the first optimal temperature according to the first beam quality parameter;

[0029] Fix the temperature of the second laser crystal to the first optimal temperature, and use the second temperature control component to gradually adjust the temperature of the third laser crystal within the second temperature range according to the second preset step size;

[0030] Receive the second beam quality parameter and the third power of the third laser crystal at each temperature value, and obtain the second optimal temperature according to the second beam quality parameter and the third power.

[0031] In a feasible implementation manner, the control method further includes:

[0032] Receive the fourth power output by the fourth power detection component; wherein, the fourth power detection component is used to detect the fourth power of the S-polarized light;

[0033] Determine whether the fourth power is within the fourth power range;

[0034] If the fourth power is not within the fourth power range, an adjustment signal is output to the motor to adjust the polarization angle of the second half-wave plate;

[0035] Receive the fifth power output by the fifth power detection component; wherein, the fifth power detection component is used to detect the fifth power of the P-polarized light;

[0036] Determine whether the fifth power is within the fifth power range;

[0037] If the fifth power is not within the fifth power range, an adjustment signal is output to the motor to adjust the polarization angle of the second half-wave plate.

[0038] In a feasible implementation manner, the control method further includes: receiving the first power output by the first power detection component;

[0039] Calculate the number of seed laser pulses based on the first power according to the preset power and pulse number correspondence;

[0040] Determine whether the number of seed laser pulses is within the preset number range;

[0041] If the number of seed laser pulses is not within the preset number range, turn off the picosecond laser system.

[0042] In a second aspect, an embodiment of the present application further provides a picosecond laser system. The picosecond laser system adopts the control method of the picosecond laser system in any technical solution of the first aspect. The picosecond laser system includes: a control module, a seed source module, a first amplification module, a second amplification module, and an output module;

[0043] The control module includes an electronic control component, a power detection component for detecting laser power, and a beam quality detection component for detecting beam quality; the electronic control component is respectively signal-connected to the power detection component and the beam quality detection component, and the electronic control component is used to provide power for the laser system; wherein, the power detection component includes a first power detection component, a second power detection component, and a third power detection component;

[0044] The seed source module is used to generate seed laser; both the first amplification module and the first power detection component are arranged downstream of the optical path of the seed source module, and the first power detection group is used to detect the first power of the seed laser;

[0045] The first amplification module is configured to amplify the seed laser to form the first laser; wherein, in the first amplification module, the incident path of the seed laser and the output path of the first laser are off-axis, and the incident direction of the seed laser and the direction of the first pump light emitted by the first amplification module are opposite;

[0046] The second power detection component and the second amplification module are both arranged downstream of the optical path of the first amplification module, and the second power detection module is used to detect the second power of the first laser;

[0047] The second amplification module includes a double-crystal structure, the double-crystal structure includes a double-crystal series connection component and a temperature control component for adjusting the temperature of the double-crystal series connection component, and the electric control component and the temperature control component are signal-connected; the second amplification module is configured to amplify the first laser in the double-crystal series connection component to form a second laser; wherein, the incident direction of the first laser input to the double-crystal series connection component and the direction of the second pump light emitted by the second amplification module are oppositely arranged;

[0048] The third power detection component, the beam quality detection component and the output module are all arranged downstream of the optical path of the second amplification module, the third power detection component is used to detect the third power of the second laser, and the beam quality detection component is used to detect the beam quality of the second laser, so that the electric control component obtains the optimal temperature value of the double-crystal series connection component according to the third power and the beam quality parameter, and enables the double-crystal series connection component to amplify the first laser at the optimal temperature value to form the second laser;

[0049] The output module is configured to modulate the second laser and then output the target laser.

[0050] In a feasible implementation manner, the double-crystal series connection component includes a second laser crystal and a third laser crystal, and the temperature control component includes a first temperature control component and a second temperature control component;

[0051] The first temperature control component is configured to control the temperature of the second laser crystal, and the second temperature control component is configured to control the temperature of the third laser crystal.

[0052] In a feasible implementation manner, the first temperature control component includes a first heat sink, a first thermoelectric cooler, and a first temperature sensor;

[0053] The second laser crystal is arranged between two first heat sinks, the two first heat sinks are used to support the second laser crystal, the first thermoelectric cooler is arranged on the surface of one of the first heat sinks, and the first thermoelectric cooler is configured to adjust the temperature of the first heat sink through current to adjust the temperature of the first laser crystal; the first temperature sensor is arranged on the first heat sink, and the first thermoelectric cooler and the first temperature sensor are respectively signal-connected to the electric control component;

[0054] The second temperature control component includes a second heat sink, a second thermoelectric cooler and a second temperature sensor;

[0055] The third laser crystal is disposed between two second heat sinks for supporting the third laser crystal. A second thermoelectric cooler is disposed on the surface of one of the second heat sinks and is configured to adjust the temperature of the third laser crystal by adjusting the temperature of the second heat sink through an electric current. A second temperature sensor is disposed on the second heat sink. The second thermoelectric cooler and the second temperature sensor are respectively connected to an electronic control component in a signal manner.

[0056] In a feasible implementation manner, the dual-crystal structure further includes a liquid-cooled radiator;

[0057] The first thermoelectric cooler and the second thermoelectric cooler are arranged side by side. The liquid-cooled radiator is disposed on the same side of the first thermoelectric cooler and the second thermoelectric cooler and is configured to dissipate heat from the first thermoelectric cooler and the second thermoelectric cooler, and the liquid-cooled radiator is connected to the electronic control component in a signal manner.

[0058] In a feasible implementation manner, the first amplification module includes a first focusing lens, a first laser crystal, a first dichroic mirror, a second focusing lens, a first collimating lens, and a first pump disposed coaxially along the transmission path of the seed laser;

[0059] The picosecond laser system includes a first beam splitter, and a first power detection component is disposed on the transmission side of the first beam splitter;

[0060] The first focusing lens is disposed on the reflection side of the first beam splitter and is configured to input the seed laser into the first laser crystal from a first path and receive the first laser output from the first laser crystal from a second path, wherein the first path and the second path are respectively disposed on both sides of the first focusing lens;

[0061] The first dichroic mirror is configured to transmit the first pump light generated by the first pump to the first laser crystal and reflect the first laser output from the first laser crystal along the second path to the first focusing lens; wherein, the first pump light and the seed laser are pumped in the first laser crystal to form the first laser;

[0062] The second focusing lens and the first collimating lens are configured to shape the first pump light and then inject it into the first laser crystal through the first dichroic mirror.

[0063] In a feasible implementation manner, the second amplification module further includes a second dichroic mirror, a third focusing lens, a second collimating lens, and a second pump;

[0064] The picosecond laser system further includes a first beam splitting component, and a second power detection component is disposed on the transmission side of the first beam splitting component;

[0065] The double-crystal structure is disposed on the reflection side of the first beam splitting component; the double-crystal structure, the second dichroic mirror, the third focusing lens, the second collimating lens, and the second pump are coaxially arranged along the transmission path of the first laser;

[0066] The second dichroic mirror is configured to transmit the second pump light generated by the second pump to the double-crystal structure and reflect the second laser output from the double-crystal structure to the output module;

[0067] The third focusing lens and the second collimating lens are configured to shape the second pump light and then inject it into the double-crystal structure through the second dichroic mirror.

[0068] In a feasible implementation, the output module includes an adjustable half-wave plate assembly, a polarization beam splitter, a first window mirror, and a second window mirror;

[0069] The laser system further includes a fifth beam splitter and a sixth beam splitter; the third power detection component is disposed on the transmission side of the fifth beam splitter, the sixth beam splitter is disposed on the reflection side of the fifth beam splitter, and the beam quality detection component is disposed on the reflection side of the sixth beam splitter;

[0070] The adjustable half-wave plate assembly is disposed on the transmission side of the sixth beam splitter. The adjustable half-wave plate assembly includes a motor and a second half-wave plate disposed at the rotating end of the motor. The motor is signal-connected to the electronic control component, and the electronic control component is configured to modulate the linear polarization angle of the second laser by controlling the rotation angle of the motor to form the third laser;

[0071] The polarization beam splitter is disposed on the output side of the third laser, and the polarization beam splitter is configured to split the beam of the third laser into P-polarized light and S-polarized light;

[0072] The first window mirror is disposed at the output end of the S optical path of the polarization beam splitter for outputting S-polarized light;

[0073] The second window mirror is disposed at the output end of the P optical path of the polarization beam splitter for outputting P-polarized light.

[0074] In a feasible implementation, the output module further includes a seventh beam splitter, an eighth beam splitter, a ninth beam splitter, a fourth power detection component, and a fifth power detection component;

[0075] The seventh beam splitter is disposed at the output end of the S optical path of the polarization beam splitter. The fourth power detection component is disposed on the reflection side of the seventh beam splitter to detect the laser power of the S-polarized light, and the first window mirror is disposed on the transmission side of the seventh beam splitter;

[0076] The eighth beam splitter is disposed at the output end of the P optical path of the polarization beam splitter. The ninth beam splitter is disposed on the reflection side of the eighth beam splitter. The fifth power detection component is disposed on the reflection side of the ninth beam splitter to detect the laser power of the P-polarized light, and the second window mirror is disposed on the transmission side of the ninth beam splitter;

[0077] The fourth power detection component and the fifth power detection component are respectively connected to the electronic control component in a signal connection manner.

[0078] In a first aspect, a control method for a picosecond laser system provided by an embodiment of the present application. In the embodiment of the present application, through the setting of the power detection component and the formation of a feedback link with the electronic control component, dynamic power calibration in the whole process of seed source injection, first-stage amplification, and second-stage amplification is realized, so as to ensure that the injection of the seed laser into the laser system, the amplification of the seed laser, and the amplification of the first laser until the output of the target laser can all be carried out under the preset state of the laser system, and a multi-level protection mechanism is constructed, thereby realizing the high stability and high reliability of the laser system. In the first amplification module, by setting the incident path of the seed laser input to the first laser crystal and the output path of the first laser output from the first laser crystal to be off-axis, that is, arranging the laser amplification circuit off-axis from the central optical axis of the gain medium, the problems of spontaneous emission, parasitic oscillation, and inadvertently formed resonant cavities existing in the traditional coaxial structure are effectively suppressed, and the beam spatial mode and the overall amplification efficiency are further improved. Further, a double-crystal structure is adopted in the second amplification module. By monitoring the third power and the beam quality parameters, the optimal temperature value of the double-crystal series-connected component is obtained, that is, on the premise of ensuring a relatively high third power, the second laser has a relatively high beam quality. After determining the optimal temperature value, the temperature of the laser crystal is closed-loop controlled by the temperature control component to compensate in real time for the refractive index change caused by the thermal lens effect, so that the double-crystal series-connected component amplifies the first laser at the optimal temperature value to obtain a second laser with relatively high laser power and good beam quality, thereby enabling the laser system to maintain a stable gain output during continuous operation. That is to say, through the setting of the embodiment of the present application, a control method for a picosecond laser system with a compact structure, high stability, high output power, and good beam quality is provided.

[0079] In a second aspect, an embodiment of the present application provides a picosecond laser system. By setting the incident path of the seed laser input to the first laser crystal and the output path of the first laser output from the first laser crystal to be off-axis, that is, arranging the laser amplification circuit off-axis from the central optical axis of the gain medium, the problems of spontaneous emission, parasitic oscillation, and inadvertently formed resonant cavities existing in the traditional coaxial structure are effectively suppressed. Combining the reverse transmission configuration of the first pump light and the seed laser enables the laser signal to obtain a higher gain density at the amplification end, thereby effectively improving the beam spatial mode and the overall amplification efficiency. Further, a double-crystal structure is adopted in the second amplification module. Through the settings of the third power detection component and the beam quality detection component, the optimal temperature value of the double-crystal series connection component can be obtained by monitoring the third power and beam quality parameters, that is, on the premise of ensuring a relatively high third power, the second laser has a relatively high beam quality. After determining the optimal temperature, the temperature of the laser crystal is closed-loop controlled by the temperature control component to compensate in real time for the refractive index change caused by the thermal lens effect, so that the double-crystal series connection component amplifies the first laser at the optimal temperature value to obtain a second laser with relatively high laser power and good beam quality, ensuring the consistency of the double-crystal gain distribution. Combining the design of reverse pumping further balances the temperature gradient inside the laser crystal, so that the laser system maintains a stable gain output during continuous operation. In the embodiment of the present application, through the setting of the power detection component and forming a feedback link with the electronic control component, dynamic power calibration is realized throughout the whole process of seed source injection, first-stage amplification, and second-stage amplification, so as to ensure that the injection of the seed laser of the laser system, the amplification of the seed laser, and the amplification of the first laser until the output of the target laser can all be carried out in the preset state of the laser system, constructing a multi-level protection mechanism, thereby realizing the high stability and high reliability of the laser system. In addition, by arranging the laser amplification circuit off-axis from the central optical axis of the gain medium, and the reverse arrangement of the pump light and the signal light, and the series connection structure of the double crystals, the structural compactness of the laser system is improved. That is to say, through the settings of the embodiment of the present application, a picosecond laser system with a compact structure, high stability, high output power, and good beam quality is provided. Description of the Drawings

[0080] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic 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:

[0081] Figure 1 is a schematic structural diagram of a picosecond laser system provided by an embodiment of the present application;

[0082] Figure 2 is Figure 1 a schematic structural diagram of the double-crystal structure in

[0083] Figure 3 The method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 1 ;

[0084] Figure 4 is Figure 3 the specific step diagram of S16 in

[0085] Figure 5 is Figure 3 the specific step diagram of S17, S18, and S19 in

[0086] Figure 6 The method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 2 ;

[0087] Figure 7 The method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 3 ;

[0088] Figure 8 is the fitting curve graph of output power and pulse number;

[0089] Figure 9 is the seed laser output wavelength data graph;

[0090] Figure 10 is the seed laser output power and stability data graph;

[0091] Figure 11 is the seed laser output pulse width data graph;

[0092] Figure 12 is the beam quality data graph of the second laser in the x direction;

[0093] Figure 13 is the beam quality data graph of the second laser in the y direction;

[0094] Figure 14 is the 5-pulse data graph of the target laser;

[0095] Figure 15 is the 10-pulse data graph of the target laser.

[0096] Explanation of reference numerals:

[0097] 200 - Seed source module; 300 - First beam splitter; 400 - First amplification module; 500 - First beam splitting component; 600 - Second amplification module; 800 - Output module; 900 - Cooling module;

[0098] 110 - Electronic control component; 120 - First power detection component; 121 - Second beam splitter; 122 - Oscilloscope; 123 - First photodetector; 130 - Second power detection component; 140 - Third power detection component; 150 - Fourth power detection component; 160 - Fifth power detection component; 170 - Beam quality detection component;

[0099] 210 - Picosecond seed source; 220 - Fiber collimator; 230 - First half-wave plate; 240 - First optical isolator;

[0100] 410 - First focusing lens; 420 - First laser crystal; 430 - First dichroic mirror; 440 - Second focusing lens; 450 - First collimating lens; 460 - First pump;

[0101] 510 - Third beam splitter; 520 - Second optical isolator; 530 - Fourth focusing lens; 540 - Fourth beam splitter;

[0102] 610 - Double crystal structure; 611 - Second laser crystal; 612 - First heat sink; 613 - First temperature sensor; 614 - First thermoelectric cooler; 615 - Third laser crystal; 616 - Second heat sink; 617 - Second temperature sensor; 618 - Second thermoelectric cooler; 619 - Liquid cooling radiator; 619a - Liquid inlet; 619b - Liquid outlet; 620 - Second dichroic mirror; 630 - Third focusing lens;

[0103] 640 - Second collimating lens; 650 - Second pump;

[0104] 701 - Fifth beam splitter; 702 - Sixth beam splitter;

[0105] 810 - Tunable half-wave plate assembly; 820 - Polarizing beam splitter; 830 - First window mirror; 840 - Second window mirror; 850 - Seventh beam splitter; 860 - Eighth beam splitter; 870 - Ninth beam splitter. Detailed implementation manners

[0106] In order to enable those skilled in the art of the present technology 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 with reference to 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. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0107] Figure 1 It is a structural schematic diagram of a picosecond laser system provided by an embodiment of this application.

[0108] Reference Figure 1 Figure 1 , an embodiment of the present application provides a picosecond laser system, which includes: a control module, a seed source module 200, a first amplification module 400, a second amplification module 600, and an output module 800;

[0109] The control module includes an electronic control component 110 and a power detection component for detecting the laser power; the electronic control component 110 is signal-connected to the power detection component, and the electronic control component 110 is used to provide power for the laser system; wherein, the power detection component includes a first power detection component 120 and a second power detection component 130;

[0110] The seed source module 200 is used to generate seed laser; both the first amplification module 400 and the first power detection component 120 are arranged downstream of the optical path of the seed source module 200, and the first power detection group is used to detect the first power of the seed laser;

[0111] The first amplification module 400 is configured to amplify the seed laser to form a first laser; wherein, in the first amplification module 400, the incident path of the seed laser and the output path of the first laser are off-axis, and the incident direction of the seed laser and the direction of the first pump light emitted by the first amplification module 400 are opposite;

[0112] The second power detection component 130 and the second amplification module 600 are both arranged downstream of the optical path of the first amplification module 400, and the second power detection module is used to detect the second power of the first laser;

[0113] The second amplification module 600 includes a double-crystal structure 610, the double-crystal structure 610 includes a double-crystal series connection component and a temperature control component for adjusting the temperature of the double-crystal series connection component, and the electronic control component 110 is signal-connected to the temperature control component; the second amplification module 600 is configured to amplify the first laser in the double-crystal series connection component to form a second laser; wherein, the incident direction of the first laser input to the double-crystal series connection component and the direction of the second pump light emitted by the second amplification module 600 are opposite;

[0114] The output module 800 is arranged downstream of the optical path of the second amplification module 600, and the output module 800 is configured to modulate the second laser and then output the target laser.

[0115] In some examples, the seed source module 200 includes a picosecond seed source 210, an optical fiber collimator 220, a first half-wave plate 230, and a first opto-isolator 240 that are sequentially arranged along the seed laser transmission path. Among them, the first seed laser output by the picosecond seed source 210 is collimated by the optical fiber collimator 220 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 second seed laser is adjusted to horizontally polarized light by the first half-wave plate 230 and then forms a seed laser through the first opto-isolator 240. The first opto-isolator 240 is used to isolate the laser returned by the device on its output side to avoid damage to the device on the input side of the first opto-isolator 240.

[0116] For example, the picosecond seed source 210 can be set as a laser with a central wavelength of 1064 nm, a pulse width of 10.2 ps, and a beam quality factor M 2 <1.1, and the repetition frequency is adjustable in the range of 500 Hz to 15 MHz.

[0117] From the above description, it can be seen that the following technical effects are achieved in this solution:

[0118] In the embodiment of the present application, by setting the incident path of the seed laser input to the first laser crystal 420 and the output path of the first laser output from the first laser crystal 420 off-axis, that is, arranging the laser amplification circuit off-axis from the central optical axis of the gain medium, the problems of spontaneous emission, parasitic oscillation, and inadvertently formed resonant cavities existing in the traditional coaxial structure are effectively suppressed. Combining the reverse transmission configuration of the first pump light and the seed laser enables the laser signal to obtain a higher gain density at the amplification end, thereby effectively improving the beam spatial mode and the overall amplification efficiency. Further, a double-crystal structure 610 is adopted in the second amplification module 600. Through the settings of the third power detection component 140 and the beam quality detection component 170, the optimal temperature value of the double-crystal series connection component can be obtained by monitoring the third power and beam quality parameters, that is, on the premise of ensuring a relatively high third power, the second laser has a relatively high beam quality. After determining the optimal temperature, the temperature of the laser crystal is closed-loop controlled by the temperature control component to compensate in real time for the refractive index change caused by the thermal lens effect, so that the double-crystal series connection component amplifies the first laser at the optimal temperature value to obtain a second laser with a relatively high laser power and good beam quality, ensuring the consistency of the double-crystal gain distribution. Combining the design of reverse pumping further balances the temperature gradient inside the laser crystal, so that the laser system maintains a stable gain output during continuous operation. In the embodiment of the present application, through the setting of the power detection component and forming a feedback link with the electronic control component, dynamic power calibration is realized throughout the whole process of seed source injection, first-stage amplification, and second-stage amplification, so as to ensure that the injection of the seed laser of the laser system, the amplification of the seed laser, and the amplification of the first laser until the output of the target laser can all be carried out under the preset state of the laser system, constructing a multi-level protection mechanism, thereby realizing the high stability and high reliability of the laser system. In addition, by arranging the laser amplification circuit off-axis from the central optical axis of the gain medium, as well as the reverse arrangement of the pump light and the signal light, and the series connection structure of the double crystals, the structural compactness of the laser system is improved. That is to say, through the settings of the embodiment of the present application, a picosecond laser system with a compact structure, high stability, high output power, and good beam quality is provided.

[0119] Figure 2 For Figure 1 The structural schematic diagram of the double-crystal structure in

[0120] In some examples, referring to Figure 2 , the double-crystal series connection component includes a second laser crystal 611 and a third laser crystal 615, and the temperature control component includes a first temperature control component and a second temperature control component; the first temperature control component is configured to regulate the temperature of the second laser crystal 611, and the second temperature control component is configured to regulate the temperature of the third laser crystal 615.

[0121] Exemplarily, both the second laser crystal 611 and the third laser crystal 615 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 420 can be designed according to the actual amplification power requirements.

[0122] In the embodiment of the present application, the temperature of the second laser crystal 611 is regulated by the first temperature control component, and the temperature of the third laser crystal 615 is regulated by the second temperature control component, so that the second laser crystal 611 and the third laser crystal 615 can be independently temperature-controlled respectively, so as to precisely regulate each crystal, thereby significantly reducing problems such as gain efficiency loss and beam quality degradation caused by uneven temperature, and thus improving the stability and reliability of the overall system.

[0123] In some examples, the picosecond laser system further includes a third power detection component 140 and a beam quality detection component 170;

[0124] Both the third power detection component 140 and the beam quality detection component 170 are arranged downstream of the optical path of the second amplification module 600. The third power detection component 140 is configured to detect the third power of the second laser, and the beam quality detection component 170 is configured to detect the beam quality of the second laser;

[0125] The temperature control component is configured to receive the third power output by the third power detection component 140 and the beam quality parameter output by the beam quality detection component 170, and determine the optimal temperature control range of the double-crystal series connection component according to the third power and the beam quality parameter.

[0126] Exemplarily, the first temperature control component includes a first heat sink 612, a first thermoelectric cooler 614, and a first temperature sensor 613;

[0127] The second laser crystal 611 is arranged between two first heat sinks 612. The two first heat sinks 612 are used to support the second laser crystal 611. The first thermoelectric cooler 614 is arranged on the surface of one of the first heat sinks 612. The first thermoelectric cooler 614 is configured to adjust the temperature of the first heat sink 612 through current to adjust the temperature of the first laser crystal 420; the first temperature sensor 613 is arranged on the first heat sink 612, and the first temperature sensor 613 is signal-connected to the electronic control component 110;

[0128] The second temperature control component includes a second heat sink 616, a second thermoelectric cooler 618, and a second temperature sensor 617;

[0129] The third laser crystal 615 is disposed between two second heat sinks 616. The two second heat sinks 616 are used to support the third laser crystal 615. The second thermoelectric cooler 618 is disposed on the surface of one of the second heat sinks 616. The second thermoelectric cooler 618 is configured to adjust the temperature of the third laser crystal 615 by adjusting the temperature of the second heat sink 616 through an electric current. The second temperature sensor 617 is disposed on the second heat sink 616, and the second temperature sensor 617 is in signal connection with the electronic control component 110.

[0130] For example, both the second laser crystal 611 and the third laser crystal 615 are wrapped with indium foil.

[0131] For another example, both the first heat sink 612 and the second heat sink 616 are configured as copper heat sinks.

[0132] In the embodiment of the present application, through the settings of the first heat sink 612 and the second heat sink 616, on the one hand, it can support the second laser crystal 611 and the third laser crystal 615, and on the other hand, it can play a role in rapid heat conduction. In the embodiment of the present application, through the settings of the first temperature sensor 613 and the second temperature sensor 617, the real-time temperatures of the second laser crystal 611 and the third laser crystal 615 can be monitored in real time through the electronic control component 110, and according to the monitored real-time temperatures, the second laser crystal 611 and the third laser crystal 615 can be respectively temperature-controlled through the first thermoelectric cooler 614 and the second thermoelectric cooler 618 to achieve precise temperature control of the second laser crystal 611 and the third laser crystal 615.

[0133] Exemplarily, the dual-crystal structure 610 further includes a liquid-cooled radiator;

[0134] The first thermoelectric cooler 614 and the second thermoelectric cooler 618 are arranged in parallel. The liquid-cooled radiator is disposed on the same side of the first thermoelectric cooler 614 and the second thermoelectric cooler 618. The liquid-cooled radiator is configured to dissipate heat from the first thermoelectric cooler 614 and the second thermoelectric cooler 618, and the thermoelectric cooler is in signal connection with the electronic control component 110.

[0135] In specific implementation, the laser system further includes a cooling module 900. The liquid-cooled radiator 619 includes a liquid inlet 619a and a liquid outlet 619b. The liquid inlet 619a and the liquid outlet 619b are respectively connected to the cooling module 900, so that the liquid-cooled radiator 619 takes away the heat on the surfaces of the first thermoelectric cooler 614 and the second thermoelectric cooler 618 through the flow of the cooling liquid, thereby reducing the influence of temperature on the second laser crystal 611 and the third laser crystal 615. While the cooling liquid in the liquid-cooled radiator 619 takes away the surface temperatures of the first thermoelectric cooler 614 and the second thermoelectric cooler 618, the temperature of the cooling liquid rises. The cooling liquid with the increased temperature enters the cooling module 900 for cooling and then enters the liquid-cooled radiator 619 through the liquid inlet 619a.

[0136] Further, in the embodiment of the present application, through the arrangement of the water-cooled radiator, the first thermoelectric cooler 614 and the second thermoelectric cooler 618 can be cooled to avoid the interference of the first thermoelectric cooler 614 and the second thermoelectric cooler 618 on the temperatures of the second laser crystal 611 and the third laser crystal 615, and ensure the stable operation of the first thermoelectric cooler 614 and the second thermoelectric cooler 618.

[0137] In some other examples, the first amplification module 400 includes a first focusing lens 410, a first laser crystal 420, a first dichroic mirror 430, a second focusing lens 440, a first collimating lens 450, and a first pump 460 that are coaxially arranged along the transmission path of the seed laser;

[0138] The picosecond laser system includes a first beam splitter 300, and the first power detection component 120 is arranged on the transmission side of the first beam splitter 300;

[0139] The first focusing lens 410 is arranged on the reflection side of the first beam splitter 300. The first focusing lens 410 is configured to input the seed laser into the first laser crystal 420 from the first path and receive the first laser output by the first laser crystal 420 from the second path. Among them, the first path and the second path are respectively arranged on both sides of the first focusing lens 410;

[0140] The first dichroic mirror 430 is configured to transmit the first pump light generated by the first pump 460 to the first laser crystal 420, and the first laser output in the first laser crystal 420 is reflected along the second path to the first focusing lens 410; among them, the first pump light and the seed laser are pumped in the first laser crystal 420 to form the first laser;

[0141] The second focusing lens 440 and the first collimating lens 450 are configured to shape the first pump light and then inject it into the first laser crystal 420 through the first dichroic mirror 430.

[0142] In specific implementation, the first path and the second path are respectively arranged on both sides of the first focusing lens 410. The angle formed by the first path and the second path is the off-axis angle between the incident path of the seed laser and the output path of the first laser. If the vertical axis angle is too large or too small, it will affect the beam quality of the output target laser.

[0143] For example, the off-axis angle can be continuously changed by moving the position where the seed laser is incident on the first focusing lens 410 and finely adjusting the left-right deflection of the first dichroic mirror 430. At the same time, a beam quality detection component is used to detect the beam quality. Since the off-axis amplification operation occurs in the horizontal direction, the beam quality of the output beam in the horizontal direction is greatly affected by the off-axis angle, while the beam quality in the vertical direction basically remains unchanged.

[0144] After testing, it is measured that when the off-axis angle ranges from [47 mrad, 57 mrad], a relatively high output power and good beam quality can be achieved. When the off-axis angle is less than 47 mrad, due to the small off-axis angle, the laser signal is affected by the thermal lens of the first laser crystal 420, resulting in an increase in the spot size, so that the spot is closer to the edge of the third beam splitter 510, and then diffraction occurs, causing a small part of the output power not to be reflected by the third beam splitter 510, and it also affects the beam quality. Further, when the off-axis angle is greater than 57 mrad, the too small off-axis angle will cause a part of the seed laser to appear outside the first pump light and cannot be effectively amplified, thus reducing the output power and beam quality.

[0145] It should be noted that the first laser crystal 420 is configured to provide a gain medium for the laser power amplification of the seed laser, and the first pump 460 is used to generate semiconductor laser to provide pump energy for the laser power amplification of the seed laser.

[0146] It should be noted that the first pump 460 can adopt multiple wavelengths such as 808 nm and 878 nm. Among them, the maximum output power of the first pump 460 is set to 60 W, and the fiber core diameter is set to 100 μm; in the first pump 460, the pump with a wavelength of 808 nm has a lower quantum deficit than the pump with a wavelength of 678 nm, which can significantly reduce the thermal effect of the laser crystal.

[0147] For example, the first dichroic mirror 430 is coated with a film that is highly transmissive to the first pump light and highly reflective to the 1064 nm laser. In specific implementation, the transmittance of the first pump light is greater than 98.5%, and the reflectivity for the seed laser (1064 nm laser) is greater than 99%.

[0148] For another example, the second focusing lens 440 and the first collimating lens 450 form a 4F optical system. Herein, the 4F optical system is an optical information processing system based on the Fourier transform principle, and its core function is to realize the spectral analysis and spatial modulation of the optical field by physical means. In specific implementation, the first collimating lens 450 is used to collimate the first pump light, and the second focusing lens 440 is used to focus the collimated first pump light into the first laser crystal 420 and match it with the seed laser transmitted by the first focusing lens 410, thereby forming a reverse single-end pumped power amplification form.

[0149] For yet another example, the second focusing lens 440 is used to focus the first pump light collimated by the first collimating lens 450. The diameter of the focused light spot is related to the focal lengths of the second focusing lens 440 and the first collimating lens 450. Let the diameter of the focused light spot be D2. The ratio of D1 to D2 is the filling factor, that is, the ratio of the diameter D1 of the collimated seed laser light spot to the diameter D2 of the collimated first pump light spot. The filling factor largely determines the coupling and matching degree between the laser beam and the pump region, and whether it is too large or too small will exacerbate the thermal effect inside the laser crystal. In order to improve the laser amplification efficiency of the picosecond laser system and ensure good beam quality at the same time, the filling factor can be designed to be 0.7 - 0.8.

[0150] In some other examples, the seed laser enters the first beam splitter 300 after passing through the first optical isolator 240. For example, the first beam splitter 300 is set as a first 45° beam splitter, wherein the first 45° beam splitter is configured to split the seed laser. In specific implementation, the first 45° beam splitter can be set 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 seed laser.

[0151] Furthermore, the first beam splitter 300 transmits a part of the seed laser to the first power detection component 120 and reflects the other part of the seed laser to the first amplification module 400.

[0152] For example, the first power detection component 120 includes a second beam splitter 121, an oscilloscope 122, and a first photodetector 123. Among them, the second beam splitter 121 is disposed on the transmission side of the first beam splitter 300, the first photodetector 123 is disposed on the transmission side of the second beam splitter 121, and the oscilloscope 122 is disposed on the reflection side of the second beam splitter 121. Among them, the second beam splitter 121 is set as a second 45° beam splitter, and the splitting ratio of the second beam splitter 121 is set to 1:1, that is, it has a 50% transmittance and a 50% reflectance for the seed laser. The first photodetector 123 is signal-connected to the electronic control component 110. The first photodetector 123 is used to convert the optical signal of the seed laser into an electrical signal and then output it to the electronic control component 110, so that the electronic control component 110 can monitor the laser power of the seed laser through the electrical signal. The oscilloscope 122 is used to monitor the output waveform of the seed laser.

[0153] In the embodiment of the present application, the seed laser is focused into the first laser crystal 420 through the first focusing lens 410. After the first pump light is collimated by the first collimating lens 450, it is then focused into the first laser crystal 420 through the first focusing lens 410. The seed laser is power-amplified inside the first laser crystal 420 to form the first laser. After the first laser is reflected by the first dichroic mirror 430, it passes through the first laser crystal 420 again, and then is coupled to the first beam splitting component 500 from the edge of the first focusing lens 410, thereby realizing the off-axis double-pass setting of the seed laser and the first laser, which not only improves the compactness of the structure, but also significantly reduces the spontaneous emission, parasitic oscillation, and accidentally formed resonant cavity oscillation commonly found in the coaxial configuration, effectively improving the spatial mode of the light beam and the overall amplification efficiency. Further, in the embodiment of the present application, the first pump light and the seed laser are transmitted in the reverse direction, which not only further improves the compactness of the structure, but also ensures that sufficient gain can still be obtained at the amplification end of the seed laser.

[0154] In some other examples, the second amplification module 600 further includes a second dichroic mirror 620, a third focusing lens 630, a second collimating lens 640, and a second pump 650;

[0155] The picosecond laser system further includes a first beam splitting component 500, and the second power detection component 130 is disposed on the transmission side of the first beam splitting component 500;

[0156] The double crystal structure 610 is disposed on the reflection side of the first beam splitting component 500; the double crystal structure 610, the second dichroic mirror 620, the third focusing lens 630, the second collimating lens 640, and the second pump 650 are coaxially disposed along the transmission path of the first laser;

[0157] The second dichroic mirror 620 is configured to transmit the second pump light generated by the second pump 650 to the double crystal structure 610 and reflect the second laser output from the double crystal structure 610 to the output module 800;

[0158] The third focusing lens 630 and the second collimating lens 640 are configured to shape the second pump light and then inject it into the double crystal structure 610 through the second dichroic mirror 620.

[0159] For example, the second collimating lens 640 and the third focusing lens 630 form a 4F optical system.

[0160] For another example, the second dichroic mirror 620 is coated with a film highly transmissive to the second pump light and a film highly reflective to the second laser (1064 nm laser). The transmittance of the second dichroic mirror 620 to the second pump light is greater than 98.5%, and the reflectivity to the second laser is greater than 99%.

[0161] For yet another example, after the second pump light is collimated by the second collimating lens 640, it is focused by the third focusing lens 630 onto the third laser crystal 615, and then matches with the first laser output from the first beam splitting component 500 through the second laser crystal 611.

[0162] Exemplarily, the third focusing lens 630 is used to focus the second pump light collimated by the second collimating lens 640. The diameter of the focused light spot is related to the focal lengths of the third focusing lens 630 and the second collimating lens 640. 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 diameter of the focused light spot D4 of the second pump 650 after collimation 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.

[0163] Exemplarily, the double crystal structure 610 is used to provide a gain medium for the laser power amplification of the first laser, and the second pump 650 is used to generate semiconductor laser to provide pump energy for the laser power amplification of the first laser.

[0164] It should be noted that the second pump 650 can adopt multiple wavelengths such as 808 nm and 878 nm. Among them, the maximum output power of the second pump 650 is set to 110 W, and the fiber core diameter is set to 400 μm. In the second pump 650, the pump with a wavelength of 808 nm has a lower quantum deficit than the pump with a wavelength of 678 nm, which can significantly reduce the thermal effect of the laser crystal.

[0165] Exemplarily, the first laser crystal 420 can adopt a Nd:YVO4 (neodymium-doped yttrium vanadate crystal) crystal, Nd 3+The doping concentration is 0.1% - 0.5%, in the form of bonding or non-bonding. Among them, the bonding form includes single-ended bonded crystal (Nd:YVO4 - YVO4) or double-ended bonded crystal (YVO4 - Nd:YVO4 - YVO4). The undoped YVO4 crystal acts as a heat sink, which is beneficial to better heat dissipation of the crystal and reduces the thermal effect of the crystal. The geometric sizes of the second laser crystal 611 and the third laser crystal 615 can be designed according to the actual amplification power requirements.

[0166] Exemplarily, the first beam splitting component 500 includes a third beam splitter 510, a second photo - isolator 520, a fourth focusing lens 530, and a fourth beam splitter 540. The seed laser forms the first laser after being amplified by the first amplification module 400. The first laser is reflected by the third 45° beam splitter to the second photo - isolator 520. The second laser passing through the second photo - isolator 520 is focused by the fourth focusing lens 530 and then reflected by the fourth beam splitter 540 and then reflected to the second amplification module 600.

[0167] Exemplarily, the focusing spot diameter of the fourth focusing lens 530 for the first laser is set to D3. Among them, the selection of D3 needs to be comprehensively considered and designed according to the structures of the first amplification module 400 and the second amplification module 600.

[0168] It should be noted that the third beam splitter 510 is set as the third 45° beam splitter, and the third beam splitter 510 is coated with an anti - reflection film for 1064nm, and the reflectivity for the first laser is greater than 99%. The second photo - isolator 520 is used to isolate the first amplification module 400 and the second amplification module 600 to prevent the laser on the output side of the second photo - isolator 520 from returning and damaging the devices on the input side of the second photo - isolator 520. The fourth beam splitter 540 is set as the fourth 45° beam splitter, and its beam splitting ratio is set to 1:99. The transmittance for 1064nm laser is 1%, and the reflectivity is 99%. That is, the fourth beam splitter 540 transmits 1% of the first laser to the second power detection component 130 and reflects 99% of the first laser to the second amplification module 600.

[0169] Exemplarily, the second power detection component 130 is set as the second photodetector, and the second photodetector is signal - connected to the electronic control component 110.

[0170] In an embodiment of the present application, the first laser is input into the double-crystal structure 610 via the first beam splitting component 500. The second pump light generated by the second pump 650 is collimated by the second collimating lens 640 and then focused onto the double-crystal structure 610 via the third focusing lens 630. The first laser and the second pump light are matched and amplified within the double-crystal structure 610 to form the second laser. The second laser is then reflected by the second dichroic mirror 620 to the fifth beam splitter 701, forming a reverse pumping structure, which not only improves the structural compactness of the picosecond laser system but also further improves the amplification efficiency of the laser power.

[0171] In another implementation, the output module 800 includes an adjustable half-wave plate assembly 810, a polarization beam splitter 820, a first window mirror 830, and a second window mirror 840;

[0172] The laser system further includes a fifth beam splitter 701 and a sixth beam splitter 702; the third power detection component 140 is disposed on the transmission side of the fifth beam splitter 701, the sixth beam splitter 702 is disposed on the reflection side of the fifth beam splitter 701, and the beam quality detection component 170 is disposed on the reflection side of the sixth beam splitter 702;

[0173] The adjustable half-wave plate assembly 810 is disposed on the transmission side of the sixth beam splitter 702. The adjustable half-wave plate assembly 810 includes a motor and a second half-wave plate disposed at the rotating end of the motor. The motor is in signal connection with the electronic control component 110, and the electronic control component 110 is configured to modulate the linear polarization angle of the second laser by controlling the rotation angle of the motor to form the third laser;

[0174] The polarization beam splitter 820 is disposed on the output side of the third laser, and the polarization beam splitter 820 is configured to split the beam of the third laser into P-polarized light and S-polarized light;

[0175] The first window mirror 830 is disposed at the output end of the S optical path of the polarization beam splitter 820 for outputting S-polarized light;

[0176] The second window mirror 840 is disposed at the output end of the P optical path of the polarization beam splitter 820 for outputting P-polarized light.

[0177] Exemplarily, the output module 800 further includes a seventh beam splitter 850, an eighth beam splitter 860, a ninth beam splitter 870, a fourth power detection component 150, and a fifth power detection component 160;

[0178] The seventh beam splitter 850 is disposed at the output end of the S optical path of the polarization beam splitter 820. The fourth power detection component 150 is disposed on the reflection side of the seventh beam splitter 850 to detect the laser power of the S-polarized light, and the first window mirror 830 is disposed on the transmission side of the seventh beam splitter 850;

[0179] The eighth beam splitter 860 is disposed at the output end of the P optical path of the polarization beam splitter 820. The ninth beam splitter 870 is disposed on the reflection side of the eighth beam splitter 860. The fifth power detection component 160 is disposed on the reflection side of the ninth beam splitter 870 to detect the laser power of the P-polarized light. The second window mirror 840 is disposed on the transmission side of the ninth beam splitter 870.

[0180] The fourth power detection component 150 and the fifth power detection component 160 are respectively connected to the electric control component 110 in signal.

[0181] It should be noted that the fifth beam splitter 701 and the sixth beam splitter 702 are respectively set as the fifth 45° beam splitter and the sixth 45° beam splitter, and both the fifth 45° beam splitter and the sixth 45° beam splitter are set as beam splitters with a beam splitting ratio of 99:1. That is, the fifth beam splitter 701 reflects 99% of the second laser to the sixth beam splitter 702, and the fifth beam splitter 701 transmits 1% of the second laser to the third power detection component 140, where the third power detection component 140 is set as the third photodetector. The sixth beam splitter 702 reflects 99% of the second laser input by the fifth beam splitter 701 to the output module 800, and outputs 1% of the second laser input by the fifth beam splitter 701 to the beam quality detection component 170.

[0182] It should be further noted that both the seventh beam splitter 850 and the ninth beam splitter 870 are set as beam splitters with a beam splitting ratio of 99:1, that is, the transmittance is 99% and the reflectance is 1%. The eighth beam splitter 860 is coated with a film with high reflectivity to the third laser (1064nm) laser, and the reflectance is greater than 99%.

[0183] Exemplarily, both the first window mirror 830 and the second window mirror 840 are used to block the influence of the external environment (such as air humidity, dust, etc.) on the laser cavity and the precision circuit. The surfaces of the first window mirror 830 and the second window mirror 840 are both coated with a high-transmission film for 1064nm laser, and the transmittance is greater than 99%.

[0184] In specific implementation, the electric control component 110 receives the output power of the S-polarized light detected by the fourth power detection component 150, and judges whether the output power of the S-polarized light is within the preset interval of the S-polarized light power. If the output power of the S-polarized light is not within the preset interval of the S-polarized light power, then the electric control component 110 will control the motor to rotate to adjust the second half-wave plate.

[0185] Similarly, the electric control component 110 receives the output power of the P-polarized light detected by the fifth power detection component 160, and judges whether the output power of the S-polarized light is within the preset interval of the P-polarized light power. If the output power of the P-polarized light is not within the preset interval of the P-polarized light power, then the electric control component 110 will control the motor to rotate to adjust the second half-wave plate.

[0186] The fourth power detection component 150 and the fifth power detection component 160 are respectively configured as a fourth photodetector and a fifth photodetector.

[0187] In an embodiment of the present application, the second laser is separated into P-polarized light and S-polarized light by a polarization beam splitter 820, and two polarization components can be obtained simultaneously at the output end of the laser system. Furthermore, the embodiment of the present application can achieve an adjustable ratio of the output power of P-polarized light and S-polarized light by setting the adjustable half-wave plate component 810. That is, through the setting of the present application, P-polarized light and S-polarized light can be used in parallel, thereby improving the flexibility and efficiency of the system, and by connecting the electronic control component 110 to the fifth power detection component 160, the sixth power detection component and the motor for signal connection, it is possible to achieve real-time regulation of the power of P-polarized light and S-polarized light, thereby achieving real-time adjustment of polarized light and improving the flexibility and stability of the system.

[0188] Figure 3 A method flow of a control method for a picosecond laser system provided in an embodiment of the present application Figure 1 .

[0189] Reference Figure 3 Based on a picosecond laser system, an embodiment of the present application further provides a control method for the picosecond laser system, the method comprising the following steps:

[0190] S11: Receive the first power output by the first power detection component 120.

[0191] The first power detection component 120 is used to detect the first power of the seed laser.

[0192] The electronic control component 110 receives the current signal of the seed laser output by the first photodetector 123 and amplifies the current signal to obtain the output power of the seed laser, ie, the first output power.

[0193] S12: Determine whether the first power is within a first preset power range.

[0194] The electronic control component 110 determines whether the first power is within a first preset power range. In specific implementation, the output power fluctuation setting range is usually within ±1% of the first preset power value.

[0195] S13: If the first power is within the first preset power range, the first amplification module 400 is turned on to perform a first-stage amplification on the seed laser to form the first laser.

[0196] In specific implementation, since the electronic control component 110 is electrically connected to the picosecond laser system, that is, the electronic control component 110 provides power for the operation of the picosecond laser system, which means the electronic control component 110 provides power for the first amplification module 400. When the electronic control component 110 determines that the first power is within the first preset power range, it will turn on the first amplification module 400.

[0197] It should be noted that when the first power is not within the first preset power range, the electronic control component 110 directly cuts off the power supply of the picosecond laser system.

[0198] S14: Receive the second power output by the second power detection component 130.

[0199] Among them, the second power detection component 130 is used to detect the second power of the first laser;

[0200] The electronic control component 110 receives the current signal of the first laser output by the second photodetector, and after amplifying the current signal, obtains the output power of the first laser, that is, the second power.

[0201] S15: Determine whether the second power is within the second preset power range.

[0202] The electronic control component 110 determines whether the second power is within the second preset power range. In specific implementation, the fluctuation setting range of the output power is usually within ±5% of the second preset power.

[0203] S16: Receive the third power output by the third power detection component 140 and the beam quality parameter output by the beam quality detection component 170, and obtain the optimal temperature value of the double crystal cascade component according to the third power and the beam quality parameter.

[0204] Among them, the third power detection component 140 is used to detect the third power of the second laser, and the beam quality detection component 170 is used to detect the beam quality of the second laser;

[0205] Among them, S16 specifically includes the following steps:

[0206] S16-1: Adjust the temperature of the third laser crystal 615 to the first temperature fixed value by using the second temperature control component.

[0207] The electronic control component 110 controls the temperature of the third laser crystal 615 by adjusting the second thermoelectric cooler 618, and adjusts the temperature of the third laser crystal 615 to the first temperature fixed value, so that the third laser crystal 615 is in a stable gain state, avoiding gain fluctuations affecting subsequent steps.

[0208] S16-2: Fix the temperature of the third laser crystal 615 to a first fixed temperature value, and use the first temperature control component to gradually adjust the temperature of the second laser crystal 611 within a first temperature range at a first preset step size.

[0209] For example, within the temperature range of 18°C to 25°C, use the first thermoelectric cooler 614 to gradually adjust the temperature of the second laser crystal 611 at a step size of 0.01°C.

[0210] S16-3: Receive the first beam quality parameter of the second laser crystal 611 at each temperature value, and obtain the first optimal temperature based on the first beam quality parameter.

[0211] The electronic control component 110 receives the first beam quality parameter of the second laser crystal 611 output by the beam quality detection component 170 at each temperature value.

[0212] Compare multiple first beam quality parameters to obtain the first optimal temperature corresponding to the optimal first beam quality parameter.

[0213] The temperature control component records the first beam quality parameter of the second laser crystal 611 at each temperature value. Each first beam quality parameter corresponds to a first beam quality factor, and each first beam quality factor corresponds to a temperature value. After comparing the values of the first beam quality factors, the minimum value of the first beam quality factor is obtained. Then, the temperature value corresponding to the minimum value of the first beam quality factor is the first optimal temperature of the second laser crystal 611. By setting a floating range around the first optimal temperature, the first optimal temperature can be obtained.

[0214] For example, the first optimal temperature is 25°C, and the floating range is set to ±0.03%.

[0215] It should be noted that the higher the beam quality, the smaller the corresponding beam quality factor.

[0216] S16-4: Fix the temperature of the second laser crystal 611 to the first optimal temperature, and use the second temperature control component to gradually adjust the temperature of the third laser crystal 615 within a second temperature range at a second preset step size.

[0217] On the premise that the temperature of the second laser crystal 611 is locked, optimize the temperature of the third laser crystal 615.

[0218] For example, within the temperature range of 18°C to 25°C, use the second thermoelectric cooler 618 to gradually adjust the temperature of the third laser crystal 615 at a step size of 0.01°C.

[0219] S16-5: Receive the second beam quality parameter and the third power of the third laser crystal 615 at each temperature value, and obtain the second optimal temperature according to the second beam quality parameter and the third power.

[0220] The electronic control component 110 records the second beam quality parameter and the third power of the third laser crystal 615 at each temperature value, screens out the parameters whose corresponding second beam quality factor of the second beam quality parameter is less than 1.3, and compares the third power corresponding to the screened second beam quality parameter to obtain the maximum third power among them. Then, the temperature value corresponding to the second beam quality factor less than 1.3 and the maximum third power is the second optimal temperature of the third laser crystal 615.

[0221] For example, the second optimal temperature is 20 °C, and the floating range is set to ±0.03%.

[0222] Among them, the third beam quality factor is the data output by the beam quality detection component 170, and the third power is the data output by the third power detection component 140.

[0223] S17: If the second power is within the second preset power range, turn on the second amplification module 600;

[0224] Furthermore, if the second power is within the second preset power range, it indicates that the first amplification module 400 can operate normally. At this time, the electronic control component 110 adjusts the working current of the first pump 460 through the PID control algorithm. For example, the working current of the first pump 460 is adjusted in steps of 0.1 A to increase or decrease the output power of the first pump 460 within a small range to ensure that the fluctuation range of the second power does not exceed ±2% of the second preset power.

[0225] Among them, the second amplification module 600 includes a temperature control component and a double crystal series connection component.

[0226] It should be noted that if the second power is not within the second preset power range, the electronic control component 110 will cut off the power supply of the laser system.

[0227] Figure 4 For Figure 3 the specific step diagram of S16 in

[0228] It should be further noted that referring to Figure 4 , S16 specifically includes the following steps:

[0229] S18: Receive the crystal temperature of the double crystal series connection component output by the temperature control component.

[0230] The electronic control component 110 receives the crystal temperatures of the double-crystal series-connected component output by the temperature control component. Since the double-crystal series-connected component includes the second laser crystal 611 and the third laser crystal 615, the electronic control component 110 respectively receives the crystal temperature of the second laser crystal 611 and the crystal temperature of the third laser crystal 615.

[0231] S19: Determine whether the crystal temperature is within the preset temperature range.

[0232] S20: If the crystal temperature is within the preset temperature range, start the PID control algorithm to adjust the crystal temperature to the optimal temperature value, so that when the crystal temperature of the double-crystal series-connected component is at the optimal temperature value, the first laser is amplified to form the second laser, and after being modulated by the output module 800, the target laser is output.

[0233] Figure 5 For Figure 3 the specific step diagrams of S17, S18, and S19 in

[0234] Refer to Figure 5 , it should be noted that S17, S18, and S19 specifically include the following steps:

[0235] S18-1: Receive the crystal temperature of the second laser crystal 611 output by the first temperature control component;

[0236] S19-1: Determine whether the temperature of the second laser crystal 611 is within the first preset temperature range;

[0237] S20-1: If the temperature of the second laser crystal 611 is within the first preset temperature range, start the PID control algorithm, and use the first temperature control component to adjust the temperature of the second laser crystal 611 to the first optimal temperature;

[0238] S18-2: Receive the crystal temperature of the third laser crystal 615 output by the second temperature control component;

[0239] S19-2: Determine whether the temperature of the third laser crystal 615 is within the second preset temperature range;

[0240] S20-2: If the temperature of the third laser crystal 615 is within the second preset temperature range, start the PID control algorithm, and use the second temperature control component to adjust the temperature of the third laser crystal 615 to the second optimal temperature, so that when the crystal temperature of the double-crystal series-connected component is at the optimal temperature value, the first laser is amplified to form the second laser, and after being modulated by the output module 800, the target laser is output.

[0241] Taking S20-1 as an example, the specific method of using the PID control algorithm and the first temperature control component to adjust the temperature of the second laser crystal 611 to the first optimal temperature is explained.

[0242] At each discrete moment, the electronic control component 110 collects the current temperature of the second laser crystal 611 .

[0243] Set the target temperature to Then the temperature error is:

[0244]

[0245] 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.

[0246] To avoid excessive integral accumulation (integral saturation) in the traditional positional PID and system jitter caused by frequent reversal of the current at both ends of the first thermoelectric cooler 614, an incremental PID method is used to calculate the change in the control signal . The operation formula is as follows:

[0247]

[0248] Where is the proportional gain, responsible for responding to the change in error; is the integral gain, participating in the product of the current cycle error and the sampling interval , helping to eliminate the steady-state error; is the derivative gain, predicting the error change through the second-order difference of the current and the previous two sampling errors; is the sampling time interval; and are the temperature errors at the previous moment and the moment before the previous moment, respectively.

[0249] This calculation method is only based on the current sampling data and the recent error change, thus naturally avoiding the saturation problem caused by excessive integral term accumulation, and making the control output update amplitude smaller when the temperature change is small, which helps to reduce system jitter.

[0250] The control output is calculated by an incremental update method:

[0251]

[0252] Where is the control signal for the th cycle, and its value corresponds to the reference value for adjusting the driving current of the second thermoelectric cooler 618. 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.

[0253] In specific implementation, taking the target temperature of the second laser crystal 611 ; the current temperature of the second laser crystal 611 measured by the second temperature control component ; seconds; ; ; PID parameters: 、 、 ; 。

[0254] Then the error is calculated as follows:

[0255]

[0256] The proportional part is calculated as follows:

[0257]

[0258] The integral part is calculated as follows:

[0259]

[0260] The derivative part is calculated as follows:

[0261]

[0262] The numerator is calculated as: Furthermore:

[0263]

[0264] The total increment and the control signal update are calculated as follows:

[0265]

[0266]

[0267] That is to say, the electronic control component 110 drives the driving current of the first thermoelectric cooler 614 to increase by 0.1805 °C, which provides a basis for adjusting the driving current of the first thermoelectric cooler 614, so that the temperature gradually approaches the target temperature.

[0268] In addition, it should be noted that in S19-2, by using the PID control algorithm, the third laser crystal 615 is adjusted to the second optimal temperature by the second temperature control component. Refer to the above method and will not be elaborated here.

[0269] In S17, for the electronic control component 110 to adjust the working current of the first pump 460 by using the PID control algorithm, also refer to the above method and will not be elaborated here.

[0270] Further, in specific implementation, the second thermoelectric cooler 618 is provided with an H-bridge circuit, which is composed of four switching components and can realize the forward and reverse switching of the second thermoelectric cooler 618. When the PID control signal is positive, the H-bridge circuit makes the current flow through the second thermoelectric cooler 618 in one direction, thereby realizing refrigeration; when is negative, the current is made to flow in the reverse direction to realize heating. The incremental PID control algorithm outputs a subtle current adjustment amount.

[0271] Of course, in S20-2, the first thermoelectric cooler 614 can also be provided with an H-bridge circuit, and the specific control method is similar to that in S17, which will not be elaborated here.

[0272] A control method for a picosecond laser system provided by an embodiment of the present application. In the embodiment of the present application, through the setting of the power detection component and the formation of a feedback link with the electronic control component, dynamic power calibration is realized in the whole process of seed source injection, first-stage amplification, and second-stage amplification, so as to ensure that the seed laser injection of the laser system, the amplification of the seed laser, and the amplification of the first laser until the output of the target laser can all be carried out under the preset state of the laser system, and a multi-level protection mechanism is constructed, thereby realizing the high stability and high reliability of the laser system. In the first amplification module, by setting the incident path of the seed laser input to the first laser crystal and the output path of the first laser output from the first laser crystal off-axis, that is, arranging the laser amplification circuit off-axis from the central optical axis of the gain medium, the spontaneous emission, parasitic oscillation, and inadvertently formed resonant cavity problems existing in the traditional coaxial structure are effectively suppressed, and the beam spatial mode and overall amplification efficiency are further improved. Further, a double-crystal structure is adopted in the second amplification module, and the optimal temperature value of the double-crystal series connection component is obtained by monitoring the third power and beam quality parameters, that is, on the premise of ensuring a relatively high third power, the second laser has a relatively high beam quality. After determining the optimal temperature value, the temperature of the laser crystal is closed-loop controlled by the temperature control component to compensate in real time for the refractive index change caused by the thermal lens effect, so that the double-crystal series connection component amplifies the first laser at the optimal temperature value to obtain a second laser with relatively high laser power and good beam quality, thereby enabling the laser system to maintain a stable gain output during continuous operation. That is to say, through the setting of the embodiment of the present application, a control method for a picosecond laser system with a compact structure, high stability, high output power, and good beam quality is provided.

[0273] Figure 6 The method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 2 。

[0274] In some other examples, referring to Figure 6, the embodiment of the present application also provides a control method for a picosecond laser system. The control method includes the following steps:

[0275] S21: Receive the fourth power output by the fourth power detection component 150.

[0276] Among them, the fourth power detection component 150 is used to detect the fourth power of the S-polarized light.

[0277] The temperature control component receives the fourth power of the S-polarized light output by the fourth power detection component 150.

[0278] S22: Determine whether the fourth power is within the fourth power range;

[0279] S23: If the fourth power is not within the fourth power range, output an adjustment signal to the motor to adjust the polarization angle of the second half-wave plate;

[0280] S24: Receive the fifth power output by the fifth power detection component 160; among them, the fifth power detection component 160 is used to detect the fifth power of the P-polarized light;

[0281] S25; Determine whether the fifth power is within the fifth power range;

[0282] S26: If the fifth power is not within the fifth power range, output an adjustment signal to the motor to adjust the polarization angle of the second half-wave plate.

[0283] Figure 7 The method flow of a control method for a picosecond laser system provided by an embodiment of the present application Figure 3 .

[0284] In another implementation, referring to Figure 7 , the embodiment of the present application also provides a control method for a picosecond laser system. The control method includes the following steps:

[0285] S31: Receive the first power output by the first power detection component 120;

[0286] S32: Calculate the number of seed laser pulses based on the first power according to the preset power and pulse number correspondence;

[0287] It should be noted that the preset power and pulse number correspondence is established based on existing experimental data. For example, in a specific experiment, the experimental devices include a picosecond seed source 210 and a photodetector. By adjusting the acousto-optic modulator of the picosecond seed source 210 to output different numbers of pulses, and recording the corresponding power at different numbers of pulses through the photodetector. Among them, the correspondence between the number of pulses and the output power is shown in Table 1.

[0288] Table 1 Corresponding Relationship Table between Pulse Number and Output Power

[0289]

[0290] Figure 8 It is the fitting curve graph of output power and pulse number.

[0291] According to the data measured in Table 1, linear regression fitting is carried out. Among them, the fitting curve is shown in Figure 8 .

[0292] Through linear regression fitting, the mathematical relationship between output power and pulse number is obtained as follows:

[0293]

[0294] Among them, P represents output power and N represents pulse number.

[0295] Refer to Figure 8 , Figure 8 The data point a1 marked in it is the data point where the output power is 10 when the pulse number is 1; the data point a2 is the data point where the output power is 17.6 when the pulse number is 2; the data point a3 is the data point where the output power is 23.9 when the pulse number is 3; the data point a4 is the data point where the output power is 28.9 when the pulse number is 4; the data point a5 is the data point where the output power is 33.4 when the pulse number is 5; the data point a2 is the data point where the output power is 37.8 when the pulse number is 6; the data point a7 is the data point where the output power is 41.6 when the pulse number is 7; the data point a8 is the data point where the output power is 45.2 when the pulse number is 8; the data point a9 is the data point where the output power is 49.6 when the pulse number is 8; the data point a10 is the data point where the output power is 53.5 when the pulse number is 10; the data point a15 is the data point where the output power is 70.1 when the pulse number is 15.

[0296] Curve A is the curve after fitting according to data points a1~a15, that is, the change curve of output power with pulse number.

[0297] S33: If the number of seed laser pulses is not within the preset number interval, then turn off the picosecond laser system.

[0298] It should be noted that in specific implementation, the number of seed laser pulses calculated 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.

[0299] Of course, if the number of corrected seed laser pulses is within the preset number range, the picosecond laser system can continue to operate.

[0300] To verify the actual application effect of a picosecond laser system, a picosecond laser system was built for testing.

[0301] The picosecond seed source 210 is a picosecond pulsed laser using SESAM (Semiconductor Saturable Absorber Mirror) mode-locking technology, with a central wavelength of 1064 nm for the output pulse, a single-pulse energy of 60 nJ, and a repetition frequency of 1 MHz.

[0302] The first laser crystal 420 is a rod-shaped YVO4 / Nd:YVO4 (yttrium vanadate) composite crystal, and the size of the first laser crystal 420 is set to 3×3×(1.5 + 19.5) mm³, where the Nd 3+ doping concentration is 0.15%. And antireflection films with wavelengths of 878 nm and 1064 nm are coated on both ends of the first laser crystal 420, with a transmittance greater than 99%.

[0303] In specific implementation, the first laser crystal 420 is wrapped in indium foil with a thickness of 0.15 mm. And the first laser crystal 420 is arranged between two third copper heat sinks, and a third thermoelectric cooler is arranged on one side of one of the third copper heat sinks. The temperature of the third copper heat sink is controlled at 18°C by the third thermoelectric cooler. The first laser crystal 420 is pumped by a first pump 460 with a wavelength of 878 nm, a core diameter of 200 μm, and an output power of 60 W. The 878-nm first pump light is sequentially adjusted in spot size by a first collimating lens 450 and a first focusing lens 410 to ensure that when the light is incident on the end face of the first laser crystal, the spot diameter is 200 μm and the filling factor reaches 0.75.

[0304] Both the second laser crystal 611 and the third laser crystal 615 are rod-shaped YVO4 / Nd:YVO4 (yttrium vanadate) composite crystals, with a doping concentration of 0.15 at% in atomic percentage, a size of 3×3×(1.5 + 19.5) mm³. Both the second laser crystal 611 and the third laser crystal 615 are wrapped in indium foil and then supported by a first copper heat sink and a second copper heat sink respectively, and the temperature is controlled by a first thermoelectric cooler 614 and a second thermoelectric cooler 618 respectively. Antireflection films with wavelengths of 878 nm and 1064 nm are coated on both ends of the second laser crystal 611 and the third laser crystal 615, with a transmittance greater than 99%.

[0305] To obtain a higher-power laser output, the output power of the second pump 650 is set to 110 W, the core diameter is 400 μm, and the pump wavelength of the second pump 650 is 878 nm. The 878-nm second pump light is adjusted in spot size by the second collimating lens 640 and the third focusing lens 630 to ensure a filling factor of 0.85.

[0306] By adjusting the first half-wave plate 230 and the polarization beam splitter 820, the polarization state of the laser is adjusted to P-polarized light to ensure that only P-polarized picosecond laser is output. The 1064-nm laser is totally reflected by the seventh beam splitter and output through the second window mirror 840.

[0307] Figure 9 It is a data graph of the output wavelength of the seed laser.

[0308] Using a spectrum analyzer, the central wavelength of the laser is measured to be 1064.17 nm. It can be referred to Figure 9 , Figure 9 In which curve B is the graph of the normalized intensity varying with the wavelength. As can be seen from Figure 9 , the central wavelength of the measured laser is 1064.17 nm. It should be noted that Figure 9 the unit a.u. of the normalized intensity in

[0309] Figure 10 is an arbitrary unit without standardization.

[0310] Using a laser power and energy meter, the average power of the 1064-nm laser is measured to be 42.01 W, and the power stability is continuously recorded at 1.25% rms with a step of 0.3 s / single shot for 4 hours. Refer to Figure 10 , curve C is the graph of the output power varying with time, and the power stability calculated by the laser power and energy meter is less than 1.25% rms.

[0311] Figure 11 It is a data graph of the output pulse width of the seed laser.

[0312] Using an autocorrelator for autocorrelation measurement, the picosecond pulse width is obtained as 10.4 ps. Refer to Figure 11 , in Figure 11 , curve D is the fitting graph of the normalized intensity varying with time, and curve E is the graph of the normalized intensity measured by the autocorrelation instrument varying with time. As can be seen from Figure 11 , the width of the picosecond pulse is 10.4 ps. It should be noted that Figure 11 the unit a.u. of the normalized intensity in

[0313] Figure 12Beam quality data graph of the second laser in the x direction; Figure 13 Beam quality data graph of the second laser in the y direction.

[0314] The beam quality of the 1064 nm laser is measured as M x 2 = 1.112, M y 2 = 1.223. Refer to Figure 12 and Figure 13 , Curve M refers to the graph of the spot radius of the second laser varying with the spot position in the x direction. Curve N refers to the graph of the spot radius of the second laser varying with the spot position in the y direction. Among them, the x direction and the y direction represent the measurement results of two orthogonal directions of the beam, Z represents the spatial position along the propagation direction of the second laser, and R represents the spot radius measured at the corresponding Z position.

[0315] Furthermore, in Figure 12 and Figure 13 in, in Figure 12 ]>in, M² being 1.112 means that the beam quality factor of the second laser in the x direction is 1.112, that is, M x 2 = 1.112.

[0316] In Figure 13 in, M² being 1.223 means that the beam quality factor of the second laser in the y direction is 1.223, that is, M y 2 = 1.223.

[0317] Figure 14 5-pulse data graph of the target laser; Figure 15 10-pulse data graph of the target laser.

[0318] Using a digital storage oscilloscope, the laser sequence in the pulse train mode is measured. Refer to Figure 14 in, Curve P is the graph of the output voltage of the target laser varying with time. It can be seen from Curve P that the target laser outputs 5 pulses. Refer to Figure 15 is the graph of the output voltage of the target laser varying with time. It can be seen from Curve Q that the target laser outputs 10 pulses.

[0319] It is easy to understand that those skilled in the art can combine, split, recombine, etc. the embodiments of the present application based on several embodiments provided by the present application to obtain other embodiments, and these embodiments do not exceed the protection scope of the present application.

[0320] In the above specific embodiments, the objectives, technical solutions, and beneficial effects of the embodiments of the present application have been further described in detail. It should be understood that the above are only the specific embodiments 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 picosecond laser system, characterized in that, Including the following steps: Receiving a first power output by a first power detection component; wherein, the first power detection component is used to detect the first power of the seed laser; Judging whether the first power is within a first preset power range; If the first power is within the first preset power range, turning on a first amplification module to amplify the seed laser to form a first laser, and in the first amplification module, the incident path of the seed laser and the output path of the first laser are arranged off-axis; Receiving a second power output by a second power detection component; wherein, the second power detection component is used to detect the second power of the first laser; Judging whether the second power is within a second preset power range; If the second power is within the second preset power range, turning on a second amplification module to amplify the first laser to form a second laser; wherein, the second amplification module includes a temperature control component and a double-crystal series connection component; Receiving a third power output by a third power detection component and a beam quality parameter output by a beam quality detection component, and obtaining an optimal temperature value of the double-crystal series connection component according to the third power and the beam quality parameter; wherein, the third power detection component is used to detect the third power of the second laser, and the beam quality detection component is used to detect the beam quality of the second laser; Receiving the crystal temperature of the double-crystal series connection component output by the temperature control component; Judging whether the crystal temperature is within a preset temperature range; If the crystal temperature is within the preset temperature range, starting a PID control algorithm to adjust the crystal temperature to the optimal temperature value, so that when the crystal temperature of the double-crystal series connection component is at the optimal temperature value, the first laser is amplified to form a second laser, and after being modulated by an output module, a target laser is output.

2. The control method of a picosecond laser system according to claim 1, characterized in that, Judging whether the crystal temperature is within a preset temperature range; If the crystal temperature is within the preset temperature range, starting a PID control algorithm to adjust the crystal temperature to the optimal temperature value, so that when the crystal temperature of the double-crystal series connection component is at the optimal temperature value, the first laser is amplified to form a second laser, and after being modulated by an output module, a target laser is output, which specifically includes the following steps: Receiving the crystal temperature of the second laser crystal output by a first temperature control component; Judging whether the second laser crystal temperature is within a first preset temperature range; If the second laser crystal temperature is within the first preset temperature range, starting a PID control algorithm and using the first temperature control component to adjust the second laser crystal temperature to a first optimal temperature; Receiving the crystal temperature of the third laser crystal output by a second temperature control component; Judging whether the third laser crystal temperature is within a second preset temperature range; If the temperature of the third laser crystal is within the second preset temperature range, start the PID control algorithm, and use the second temperature control component to adjust the temperature of the third laser crystal to the second optimal temperature, so that when the crystal temperature of the double-crystal series connection component is at the optimal temperature value, the first laser is amplified to form the second laser, and after being modulated by the output module, the target laser is output.

3. The control method of a picosecond laser system according to claim 2, characterized in that The steps of receiving the third power output by the third power detection component and the beam quality parameter output by the beam quality detection component, and obtaining the optimal temperature value of the double-crystal series connection component specifically include: Adjust the temperature of the third laser crystal to the first temperature fixed value by using the second temperature control component; Fix the temperature of the third laser crystal to the first temperature fixed value, and use the first temperature control component to gradually adjust the temperature of the second laser crystal within the first temperature range according to the first preset step size; Receive the first beam quality parameter of the second laser crystal at each temperature value, and obtain the first optimal temperature according to the first beam quality parameter; Fix the temperature of the second laser crystal to the first optimal temperature, and use the second temperature control component to gradually adjust the temperature of the third laser crystal within the second temperature range according to the second preset step size; Receive the second beam quality parameter and the third power of the third laser crystal at each temperature value, and obtain the second optimal temperature according to the second beam quality parameter and the third power.

4. A control method for a picosecond laser system according to any one of claims 1-3, characterized in that, The control method further includes: Receive the fourth power output by the fourth power detection component; wherein, the fourth power detection component is used to detect the fourth power of the S-polarized light; Judge whether the fourth power is within the fourth power range; If the fourth power is not within the fourth power range, output an adjustment signal to the motor to adjust the polarization angle of the second half-wave plate; Receive the fifth power output by the fifth power detection component; wherein, the fifth power detection component is used to detect the fifth power of the P-polarized light; Judge whether the fifth power is within the fifth power range; If the fifth power is not within the fifth power range, output an adjustment signal to the motor to adjust the polarization angle of the second half-wave plate.

5. A control method for a picosecond laser system according to any one of claims 1-3, characterized in that, The control method further includes: Receive the first power output by the first power detection component; Calculate the number of seed laser pulses according to the preset power and pulse number correspondence relationship of the first power; Judge whether the number of seed laser pulses is within the preset number range; If the number of seed laser pulses is not within the preset number range, turn off the picosecond laser system.

6. A picosecond laser system, characterized in that, The picosecond laser system adopts the control method of the picosecond laser system according to any one of claims 1-5. The picosecond laser system includes: a control module, a seed source module, a first amplification module, a second amplification module and an output module; The control module includes an electronic control component, a power detection component for detecting the laser power, and a beam quality detection component for detecting the beam quality; the electronic control component is respectively connected to the power detection component and the beam quality detection component in signal, and the electronic control component is used to provide power for the laser system; wherein, the power detection component includes a first power detection component, a second power detection component and a third power detection component; The seed source module is used to generate seed laser; both the first amplification module and the first power detection component are arranged downstream of the optical path of the seed source module, and the first power detection component is used to detect the first power of the seed laser; The first amplification module is configured to amplify the seed laser to form a first laser; wherein, in the first amplification module, the incident path of the seed laser and the output path of the first laser are arranged off-axis, and the incident direction of the seed laser and the direction of the first pump light emitted by the first amplification module are arranged oppositely; Both the second power detection component and the second amplification module are arranged downstream of the optical path of the first amplification module, and the second power detection module is used to detect the second power of the first laser; The second amplification module includes a double-crystal structure, the double-crystal structure includes a double-crystal series connection component and a temperature control component for adjusting the temperature of the double-crystal series connection component, and the electronic control component and the temperature control component are connected in signal; the second amplification module is configured to amplify the first laser in the double-crystal series connection component to form the second laser; wherein, the incident direction of the first laser input to the double-crystal series connection component and the direction of the second pump light emitted by the second amplification module are arranged oppositely; Both the third power detection component, the beam quality detection component and the output module are arranged downstream of the optical path of the second amplification module, the third power detection component is used to detect the third power of the second laser, and the beam quality detection component is used to detect the beam quality of the second laser, so that the electronic control component can obtain the optimal temperature value of the double-crystal series connection component according to the third power and the beam quality parameter, and enable the double-crystal series connection component to amplify the first laser at the optimal temperature value to form the second laser; The output module is configured to modulate the second laser and then output the target laser.

7. A picosecond laser system according to claim 6, characterized in that, The double-crystal series connection component includes a second laser crystal and a third laser crystal, and the temperature control component includes a first temperature control component and a second temperature control component; The first temperature control component is configured to control the temperature of the second laser crystal, and the second temperature control component is configured to control the temperature of the third laser crystal.

8. A picosecond laser system according to claim 7, characterized in that, The first temperature control component includes a first heat sink, a first thermoelectric cooler, and a first temperature sensor; The second laser crystal is disposed between the two first heat sinks, and the two first heat sinks are used to support the second laser crystal. The first thermoelectric cooler is disposed on the surface of one of the first heat sinks, and the first thermoelectric cooler is configured to adjust the temperature of the first heat sink by passing an electric current to adjust the temperature of the first laser crystal. The first temperature sensor is disposed on the first heat sink, and the first thermoelectric cooler and the first temperature sensor are respectively in signal connection with the electronic control component; The second temperature control component includes a second heat sink, a second thermoelectric cooler and a second temperature sensor; The third laser crystal is disposed between the two second heat sinks, and the two second heat sinks are used to support the third laser crystal. The second thermoelectric cooler is disposed on the surface of one of the second heat sinks, and the second thermoelectric cooler is configured to adjust the temperature of the second heat sink by passing an electric current to adjust the temperature of the third laser crystal. The second temperature sensor is disposed on the second heat sink, and the second thermoelectric cooler and the second temperature sensor are respectively in signal connection with the electronic control component.

9. A picosecond laser system according to claim 8, wherein The dual-crystal structure further includes a liquid-cooled radiator; The first thermoelectric cooler and the second thermoelectric cooler are arranged in parallel, and the liquid-cooled radiator is disposed on the same side of the first thermoelectric cooler and the second thermoelectric cooler. The liquid-cooled radiator is configured to dissipate heat from the first thermoelectric cooler and the second thermoelectric cooler, and the liquid-cooled radiator is in signal connection with the electronic control component.

10. A picosecond laser system according to any one of claims 6-9, characterized in that, The first amplification module includes a first focusing lens, a first laser crystal, a first dichroic mirror, a second focusing lens, a first collimating lens and a first pump disposed coaxially along the transmission path of the seed laser; The picosecond laser system includes a first beam splitter, and the first power detection component is disposed on the transmission side of the first beam splitter; The first focusing lens is disposed on the reflection side of the first beam splitter. The first focusing lens is configured to input the seed laser into the first laser crystal from a first path and receive the first laser output from the first laser crystal from a second path. Among them, the first path and the second path are respectively disposed on both sides of the first focusing lens; The first dichroic mirror is configured to transmit the first pump light generated by the first pump to the first laser crystal and reflect the first laser output from the first laser crystal along the second path to the first focusing lens. Among them, the first pump light and the seed laser are pumped in the first laser crystal to form the first laser; The second focusing lens and the first collimating lens are configured to shape the first pump light and then inject it into the first laser crystal through the first dichroic mirror.

11. A picosecond laser system according to claim 6, characterized in that, The second amplification module further includes a second dichroic mirror, a third focusing lens, a second collimating lens and a second pump; The picosecond laser system further includes a first beam splitting component, and the second power detection component is disposed on the transmission side of the first beam splitting component; The double-crystal structure is arranged on the reflection side of the first beam splitting component; the double-crystal structure, the second dichroic mirror, the third focusing lens, the second collimating lens, and the second pump are coaxially arranged along the transmission path of the first laser; The second dichroic mirror is configured to transmit the second pump light generated by the second pump to the double-crystal structure and reflect the second laser output from the double-crystal structure to the output module; The third focusing lens and the second collimating lens are configured to shape the second pump light and then inject it into the double-crystal structure through the second dichroic mirror.

12. A picosecond laser system according to any one of claims 6-9, characterized in that, The output module includes an adjustable half-wave plate assembly, a polarization beam splitter, a first window mirror, and a second window mirror; The laser system further includes a fifth beam splitter and a sixth beam splitter; the third power detection component is arranged on the transmission side of the fifth beam splitter, the sixth beam splitter is arranged on the reflection side of the fifth beam splitter, and the beam quality detection component is arranged on the reflection side of the sixth beam splitter; The adjustable half-wave plate assembly is arranged on the transmission side of the sixth beam splitter. The adjustable half-wave plate assembly includes a motor and a second half-wave plate arranged at the rotating end of the motor. The motor is signal-connected to the electronic control component, and the electronic control component is configured to modulate the linear polarization angle of the second laser by controlling the rotation angle of the motor to form a third laser; The polarization beam splitter is arranged on the output side of the third laser, and the polarization beam splitter is configured to split the beam of the third laser into P-polarized light and S-polarized light; The first window mirror is arranged at the output end of the S optical path of the polarization beam splitter for outputting S-polarized light; The second window mirror is arranged at the output end of the P optical path of the polarization beam splitter for outputting P-polarized light.

13. A picosecond laser system according to claim 12, characterized in that, The output module further includes a seventh beam splitter, an eighth beam splitter, a ninth beam splitter, a fourth power detection component, and a fifth power detection component; The seventh beam splitter is arranged at the output end of the S optical path of the polarization beam splitter. The fourth power detection component is arranged on the reflection side of the seventh beam splitter to detect the laser power of the S-polarized light, and the first window mirror is arranged on the transmission side of the seventh beam splitter; The eighth beam splitter is arranged at the output end of the P optical path of the polarization beam splitter. The ninth beam splitter is arranged on the reflection side of the eighth beam splitter. The fifth power detection component is arranged on the reflection side of the ninth beam splitter to detect the laser power of the P-polarized light, and the second window mirror is arranged on the transmission side of the ninth beam splitter; The fourth power detection component and the fifth power detection component are respectively signal-connected to the electronic control component.

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