Q-switched laser capable of improving emergent light power climbing and light leakage and laser Q-switched output method

Abstract

The invention discloses a double-resonant-cavity Q-switched laser, which is characterized in that the diffraction direction of light is changed by applying or not applying radio frequency power through a Q switch, so that the conversion between a main resonant cavity and an auxiliary resonant cavity is realized. The auxiliary resonant cavity is used for releasing energy when light is turned off, so that the climbing phenomenon of output light energy is improved, and stable output light power is provided; and moreover, by changing the polarization direction of the light to the auxiliary resonant cavity, the damage to the photosensitive material and the damage to equipment caused by light leakage after the light is turned off are avoided, more stable processing capability can be provided, the processing technology is optimized, and the structure is simple.

Description

Technical Field

[0001] The present application belongs to the field of optical devices, and specifically relates to a Q-switched laser with improved output power ramping and light leakage, and a laser Q-switched output method. Background Art

[0002] Q-switched nanosecond laser is a laser widely used in industrial processing. It achieves precise control of laser pulse width and repetition frequency by changing the Q value of the laser cavity, thereby meeting various processing requirements.

[0003] Among Q-switched nanosecond lasers, nanosecond green lasers and nanosecond ultraviolet lasers based on intracavity frequency doubling are the most commonly used types. They improve the efficiency of frequency conversion by increasing the reflectivity of the intracavity mirror to the fundamental frequency light. In order to enable the laser to respond quickly to the external trigger signal, the pump light will be continuously applied to the laser crystal. When the external trigger signal turns off the Q-switched nanosecond laser, a large amount of heat will accumulate on the laser crystal. When the external trigger signal turns on the laser again, the output laser will experience a power ramp-up process (ramp-up phenomenon) in which the power / energy changes from weak to strong, that is, the process in which the heat release reaches equilibrium.

[0004] When the laser receives an external trigger signal to turn off the light, the RF power applied to the acousto-optic Q switch is reduced or directly removed, so that the laser is in a continuous resonance mode, which may improve the power climbing phenomenon. However, at this time, the laser will actually output a weak leakage light when the light is turned off. When processing some materials that are very sensitive to lasers, this leakage light will cause the material to be scratched. For example, in processing methods based on galvanometers or cutting heads, traces of light leakage damaging the material can be observed in the optical path trajectory between processing areas. This not only affects the processing quality, but may also cause damage to the equipment. Therefore, how to effectively solve the climbing phenomenon of Q-switched nanosecond lasers when they re-emitter after turning off the light, while avoiding light leakage, is a problem that needs to be solved urgently in this field. Summary of the invention

[0005] In order to improve the defects of the prior art, the present application proposes a Q-switched laser including a main resonant cavity and an auxiliary resonant cavity, which can achieve optical power ramping and light leakage improvement, and further proposes a laser Q-switched output method.

[0006] The present application provides a Q-switched laser with improved output power ramping and light leakage, including:

[0007] A first reflector, a laser crystal, a Q switch, a first dichroic mirror, a laser frequency conversion module, and a second reflector arranged along a first direction, a thin-film polarizer, a quarter-wave plate, and a third reflector, and a heat sink arranged along a second direction;

[0008] Wherein, a main resonant cavity is formed between the first reflector and the second reflector;

[0009] An auxiliary resonant cavity is formed between the first reflector and the third reflector;

[0010] The heat sink is arranged at the light output end of the auxiliary resonant cavity.

[0011] In one embodiment, the second direction is a diffraction light output direction of the Q switch.

[0012] In one embodiment, the first dichroic mirror includes a first surface and a second surface, the first surface faces the Q switch side, the second surface faces the frequency conversion module side, and the second surface reflects the laser to guide the laser out of the main resonant cavity.

[0013] In one embodiment, the transmittance of the first surface of the first dichroic mirror to the output light of the Q switch is greater than 99.5%, and the reflectance of the second surface to the output light after frequency conversion by the frequency conversion module is greater than 99.5%.

[0014] In one embodiment, a second dichroic mirror is further provided in the output direction of the light reflected by the first dichroic mirror, and the second dichroic mirror totally reflects the light reflected by the first dichroic mirror.

[0015] In one embodiment, the frequency conversion module is selected from at least one frequency doubling crystal or a combination of a frequency doubling crystal and a frequency tripling crystal.

[0016] In one embodiment, the quarter wave plate is rotatable, and the thin film polarizer has a third surface and a fourth surface, the third surface faces the Q switch, and the fourth surface faces the quarter wave plate. After the laser is diffracted by the Q switch, it is transmitted through the third surface of the thin film polarizer along the second direction, and then propagates through the quarter wave plate to the third reflector for reflection, and then passes through the quarter wave plate again to the fourth surface of the thin film polarizer, is reflected on the fourth surface of the thin film polarizer, is guided out of the auxiliary resonant cavity, and is output to the heat sink for absorption.

[0017] In one embodiment, the Q-switched laser further comprises a pump light source and an electrical control system, wherein the electrical control system is configured to apply or withdraw radio frequency power to the Q switch.

[0018] In one embodiment, the Q switch is an acousto-optic modulator or an electro-optic modulator.

[0019] In one embodiment, the laser crystal is Nd:YVO 4 Laser crystal, Nd:YAG crystal, Nd:YLF crystal, Nd:KGW crystal, Yb:YVO 4Crystal, Yb:YAG crystal, Yb:YLF crystal, Yb:KGW crystal, Pr:YLF crystal, Pr:YAP crystal, Pr:LiLuF 4 Crystal, Pr:LaF 3 One of Ti:Sapphire crystal and Ti:Sapphire crystal.

[0020] The present application also provides a laser Q-switched output method, comprising:

[0021] providing a laser as described above;

[0022] When the laser is in an initial state where no light output signal is received, radio frequency power is applied to the Q switch to make the laser resonate along the second direction in the auxiliary resonant cavity, and the redundant laser is guided out of the auxiliary resonant cavity to the heat sink for absorption by the thin film polarizer;

[0023] When the laser is in the working state of receiving the light output signal, the RF power is removed, the laser resonates along the first direction in the main resonant cavity, generates a pulse laser at the moment of light output and after reaching a constant output power, it is guided out of the main resonant cavity by the first dichroic mirror to the second dichroic mirror for output.

[0024] In one embodiment, the method is implemented via the aforementioned laser.

[0025] In one embodiment, the angle of the quarter wave plate is adjusted to change the output power of the thin film polarizer to the redundant laser, the angle adjustment range of the quarter wave plate is 0° to 45°, and the output power range of the redundant laser is 0 to 100W.

[0026] Beneficial effects of this application:

[0027] The laser provided in the present application is provided with an auxiliary resonant cavity and a main resonant cavity, which share a first reflector, a laser crystal and a Q switch. The diffraction direction of the light is changed by applying or not applying RF power through the Q switch, thereby realizing the conversion between the main resonant cavity and the auxiliary resonant cavity. The energy released by the auxiliary resonant cavity when the light is turned off improves the output light energy climbing phenomenon and provides a stable output light power; and by changing the polarization direction of the light to the auxiliary resonant cavity, the damage to the photosensitive material and the equipment caused by the leakage of light after the light is turned off is avoided, and a more stable processing capability can be provided, and the processing technology is optimized. The structure is simple, and it can be applied to high-precision and high-efficiency laser processing technology. It can also be used in the manufacture of optical devices, optoelectronic devices and other related devices, and has a wide range of application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for describing the embodiments are briefly introduced below.

[0029] Figure 1: are pulse laser waveform diagrams of lasers, (a) is a pulse laser waveform diagram of a laser when no auxiliary resonant cavity is provided in the prior art, (b) is a pulse laser waveform diagram of a laser of an embodiment of the present application;

[0030] Figure 2 This is a schematic diagram of the structure of a laser according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0032] When the laser in the laser is modulated by Q switching, taking the acousto-optic modulator as an example, in the case of only the main resonant cavity, when RF power is applied to the acousto-optic modulator, ultrasonic waves are formed through electroacoustic conversion to cause periodic changes in the refractive index of the modulating medium, diffracting the incident light, causing diffraction loss, Q value decreases, laser oscillation cannot be formed, and energy accumulates in the laser crystal. When the number of upper energy level inversion particles continues to accumulate and reaches the saturation value under the stimulation of the pump light source, the RF signal is turned off, the ultrasonic field is suddenly removed, the diffraction effect disappears immediately, the Q value in the cavity soars, the laser oscillation recovers quickly, and its energy is output in the form of pulses. However, at the moment when the energy is suddenly output in the form of pulses, the laser crystal changes from the energy storage state to the energy release state, and there is a process of reaching thermal equilibrium, that is, a slowly increasing power climbing phenomenon occurs. The actual waveform of the oscilloscope is as follows Figure 1 As shown in (a). If no RF power is applied to the Q switch in the off state, the resonant cavity keeps outputting continuous laser. When the pulsed laser is output after the Q switch works, thermal equilibrium can be reached quickly and the ramp phenomenon is alleviated. However, continuous laser leads to light leakage, which may damage the processed materials or equipment.

[0033] Based on this, an embodiment of the present application provides a Q-switched laser, comprising a first reflector, a laser crystal, a Q switch, a first dichroic mirror, a second dichroic mirror, a laser frequency conversion module, and a second reflector arranged along a first direction, and a thin-film polarizer, a quarter-wave plate, and a third reflector arranged along a second direction; wherein a main resonant cavity is formed between the first reflector and the second reflector;

[0034] An auxiliary resonant cavity is formed between the first reflector and the third reflector;

[0035] A heat sink is arranged at the light output end of the auxiliary resonant cavity;

[0036] The second direction is the diffraction light output direction of the Q switch.

[0037] The auxiliary resonant cavity and the main resonant cavity of the Q-switched laser share the first reflector, the laser crystal and the Q switch, so that in the off-light state without outputting the pulsed laser, the radio frequency power can still be applied to the Q switch to maintain the thermal equilibrium state of the laser crystal, and the auxiliary resonant cavity arranged in the output direction of the Q-switch diffraction light releases part of the energy stored in the laser crystal when the light is off, so as to help quickly reach thermal equilibrium at the moment of pulse light output after receiving the output light signal, improve the output light energy climbing phenomenon, make the output pulse laser reach the maximum pulse intensity in a very short time, and provide stable output light power, such as Figure 1 (b) As shown; and part of the light output from the auxiliary resonant cavity in the diffraction direction is absorbed by the heat sink, thereby avoiding the damage of continuous laser output leakage to the photosensitive material and the damage to the equipment, providing more stable processing capabilities and optimizing the processing technology.

[0038] In some embodiments, the main resonant cavity includes a first reflector, a laser crystal, a Q switch, a first dichroic mirror, a second dichroic mirror, a frequency conversion module, and a second reflector in order in a first direction. The laser can resonate in the resonant cavity along the first direction. It can be understood that the first direction is a line connecting the optical axes of the components of the main resonant cavity, and the laser can resonate in the main resonant cavity along the first direction.

[0039] In the main resonant cavity, the laser light source is output through the laser crystal and the Q switch, and then propagates to the first dichroic mirror. The first dichroic mirror includes a first surface and a second surface. The first surface faces the Q switch side, and the second surface faces the frequency conversion module side. The first dichroic mirror can transmit the output light of the Q switch by the first surface, and the second surface has a reflective effect on the light after the frequency conversion module is converted, and the laser is guided out of the main resonant cavity and output. A second dichroic mirror is arranged at the reflected light output end of the first dichroic mirror, and the second dichroic mirror outputs a part of the laser of the main resonant cavity as an output mirror. The second dichroic mirror has a fifth surface facing the first dichroic mirror and a sixth surface facing away from the first dichroic mirror.

[0040] The transmittance of the first surface of the first dichroic mirror to the output light of the Q switch is greater than 99.5%, and the reflectance of the second surface to the output light after the frequency conversion of the frequency conversion module is greater than 99.5%. In some embodiments, the first surface coating of the first dichroic mirror is a 1064nm anti-reflection film, which has a transmittance of ≥99.5% for a wavelength of 1064nm, and the coating on the second surface is a 532nm / 355nm total reflection film, which has a reflectance of ≥99.5% for a wavelength of 532nm / 355nm.

[0041] In a specific embodiment, the fifth surface coating of the second dichroic mirror is a 532nm anti-reflection film and a 355nm total reflection film, and the transmittance of light at a wavelength of 532nm is ≥99.5%, and the reflectivity of light at a wavelength of 355nm is 99.5%; the sixth surface coating is a 532nm anti-reflection film, and the transmittance of light at a wavelength of 532nm is 99.5%.

[0042] In a specific embodiment, the surface coating of the first reflector is a 1064nm total reflection film, and the reflectivity of light with a wavelength of 1064nm is ≥99.5%. The surface coating of the second reflector is a 1064nm / 532nm total reflection film, and the transmittance and reflectivity of light with a wavelength of 1064nm / 532nm is ≥99.5%.

[0043] In one embodiment, the laser crystal is Nd:YVO 4 Laser crystal. The Q switch is selected from any one of an acousto-optic modulator and an electro-optic modulator. Preferably, the Q switch is an acousto-optic modulator with an operating frequency of 21 to 110 MHz.

[0044] In some embodiments, the frequency conversion module is selected from at least one double frequency crystal or a combination of a double frequency crystal and a triple frequency crystal. For example, a double frequency crystal and a triple frequency crystal are connected in series, or a double frequency crystal is provided alone.

[0045] In some embodiments, the auxiliary resonant cavity is provided with a first reflector, a laser crystal, a Q switch, a thin film polarizer, a quarter wave plate and a third reflector in sequence. The second direction is the propagation direction of the diffracted light of the Q switch, and when radio frequency power is applied to the Q switch, the light output from the output end of the Q switch can resonate along the second direction.

[0046] The quarter wave plate is rotatable, and the output optical power of the auxiliary resonant cavity can be adjusted by rotating the angle of the quarter wave plate to avoid affecting the energy storage of the laser crystal and reduce the impact on the laser power in the normal light output state. In some embodiments, adjusting the angle of the quarter wave plate can change the output power of the thin film polarizer to the redundant laser. The angle adjustment range of the quarter wave plate is 0° to 45°, and the output power range of the redundant laser is 0 to 100w.

[0047] The heat sink is arranged at the reflected light output end of the thin film polarizer to absorb the excess energy accumulated in the cavity. In some embodiments, the quarter wave plate can be made of quartz.

[0048] The thin film polarizer has a third surface and a fourth surface, the third surface faces the Q switch, and the fourth surface faces the quarter wave plate. The laser is diffracted by the Q switch and transmitted along the second direction through the third surface of the thin film polarizer, and then propagates through the quarter wave plate to the third reflector for reflection, and then passes through the quarter wave plate again to the fourth surface of the thin film polarizer, and is reflected on the fourth surface of the thin film polarizer, and is led out of the auxiliary resonant cavity and output to the heat sink for absorption.

[0049] In some embodiments, the fourth surface coating of the thin film polarizer is a 1064nm polarizing film layer, the incident angle is 45 degrees to 80 degrees, the transmittance for p-polarized laser is ≥99%, the reflectivity for s-polarized laser is ≥99.8%, and the wavelength range is 900 to 1300nm. The surface coating of the third reflector is a 1064nm total reflection film, and the reflectivity for light of 1064nm wavelength is ≥99.5%. The heat sink is any known device with heat dissipation function, selected from metal heat sink materials such as copper heat sinks, non-metallic materials such as diamond, silicon carbide heat sinks, etc.

[0050] In some embodiments, the Q-switched laser further includes a pump light source. The pump light source is disposed on one side of the laser crystal, and its type is not particularly limited, and a light source of a desired wavelength can be output, for example, 880nm, 878nm, 808nm or other wavelengths. The pump light source can be end-pumped or side-pumped. When end-pumped, the pump light source is disposed on one side of the first reflector, and the first reflector is transmissive to the pump light source, and the light source is transmitted by the first reflector to reach the laser crystal. When side-pumped, the pump light source reaches the laser crystal from the side perpendicular to the light propagation direction (first direction).

[0051] In some embodiments, the Q-switched laser further includes an electric control system. The electric control system is configured to apply or not apply radio frequency power to the Q switch. The electric control system may be any known circuit system for realizing signal reception and feedback, and may include a power supply module, a signal input and output module, a control module, and an execution module. The electric control system may apply radio frequency power to the Q switch or turn off radio frequency power according to an external light output signal or a light off signal, thereby realizing periodic adjustment of the refractive index of the Q switch modulation medium and realizing the output of pulsed laser.

[0052] The embodiment of the present application also provides a Q-switched laser output method with improved power ramping and light leakage, including:

[0053] A Q-switched laser is provided, comprising a first reflector, a laser crystal, a Q switch, a first dichroic mirror, a second dichroic mirror, a laser frequency conversion module and a second reflector arranged along a first direction, a thin-film polarizer, a quarter-wave plate and a third reflector arranged along a second direction, and a heat sink arranged at a light output end of an auxiliary resonant cavity;

[0054] Wherein, a main resonant cavity is formed between the first reflector and the second reflector;

[0055] An auxiliary resonant cavity is formed between the first reflector and the third reflector, and the second direction is the diffracted light output direction of the Q switch;

[0056] When the laser is in an initial state where no light output signal is received, radio frequency power is applied to the Q switch to make the laser resonate along the second direction in the auxiliary resonant cavity, and the redundant laser is guided out of the auxiliary resonant cavity to the heat sink for absorption by the thin film polarizer;

[0057] When the laser is in the working state of receiving the light output signal, the RF power is removed, the laser resonates in the main resonant cavity along the first direction, generates a pulse laser at the moment of light output and outputs after reaching a constant output power.

[0058] In one embodiment, the method further comprises adjusting the angle of the quarter wave plate to change the output power of the thin film polarizer to the redundant laser.

[0059] In one embodiment, the output power of the redundant laser in the auxiliary resonant cavity is less than the constant output power of the pulsed laser in the main resonant cavity.

[0060] Through the Q-switched laser output method of this embodiment, since the laser is in the state of outputting laser in the initial state, the energy of the laser crystal is released to a certain extent. Therefore, when it is converted to the working state, the main resonant cavity can also quickly reach thermal equilibrium, the output laser instantly reaches a constant power, and the laser pulse quickly reaches a constant pulse energy, thereby solving the problem of optical power climbing and avoiding the adverse consequences such as material damage and equipment damage caused by the use of leakage light output through the main resonant cavity.

[0061] In some embodiments, the method is implemented by the aforementioned Q-switched laser.

[0062] The following specific embodiments are provided to further illustrate the technical solution of the present application.

[0063] Example 1 Power-stable Q-switched laser

[0064] Pump light source: output wavelength is 808nm, output power is 80w;

[0065] Laser crystal 2: Nd:YVO 4 Laser crystal, size 4mm×4mm×20mm;

[0066] Acousto-optic modulator 3: operating frequency 41MHz;

[0067] First reflector 1: The surface coating is a 1064nm total reflection film, the reflectivity of the light with a wavelength of 1064nm is 99.9%, the diameter is 12.7mm, and the thickness is 6mm;

[0068] First dichroic mirror 8: the first surface coating is a 1064nm antireflection film, the transmittance of light at a wavelength of 1064nm is 99.5%, the second surface coating is a 532nm / 355nm total reflection film, the reflectivity of light at a wavelength of 532nm / 355nm is 99.5%, the diameter is 12.7mm, and the thickness is 3mm;

[0069] Second dichroic mirror 9: the fifth surface coating is a 532nm anti-reflection film and a 355nm total reflection film, the transmittance of light at a wavelength of 532nm is 99.5%, the reflectance of light at a wavelength of 355nm is 99.5%, the sixth surface coating is a 532nm anti-reflection film, the transmittance of light at a wavelength of 532nm is 99.5%, the diameter is 12.7mm, and the thickness is 6mm;

[0070] Frequency conversion module 10: Double frequency crystal: LBO crystal, size 4mm×4mm×10mm; Triple frequency crystal: LBO crystal, size 4mm×4mm×20mm;

[0071] Second reflector 11: surface coating is 1064nm / 532nm total reflection film, reflectivity of light with wavelength of 1064nm / 532nm is 99.5%, diameter is 12.7mm, thickness is 6mm;

[0072] Thin film polarizer 4: The fourth surface coating facing the quarter wave plate is a 1064 nm polarizing film layer, the incident angle is 56.5 degrees, the transmittance for p-polarized laser is 99.5%, the reflectivity for s-polarized laser is 99.9%, and the size is 25 mm × 15 mm × 2 mm;

[0073] Quarter wave plate 5: quartz material, diameter 12.7mm, thickness 1mm;

[0074] The third reflector 6: the surface coating is a 1064nm total reflection film, the reflectivity of the light with a wavelength of 1064nm is 99.9%, the diameter is 12.7mm, and the thickness is 6mm;

[0075] Heat sink 7: copper material, size 40mm×30mm×20mm;

[0076] The length of the first resonant cavity: 200mm;

[0077] The second resonant cavity length: 150mm;

[0078] like Figure 2 As shown, the first reflector, laser crystal, Q switch, first dichroic mirror, frequency conversion module and second reflector arranged in sequence form a main resonant cavity, and the optical centers of each device are located on a straight line, which is the optical axis along the first direction.

[0079] The first reflector, laser crystal, Q switch, thin film polarizer, quarter wave plate and third reflector are arranged in sequence to form an auxiliary resonant cavity. Starting from the thin film polarizer, they are arranged in the propagation direction of the diffracted light of the Q switch (the second direction). When radio frequency power is applied to the Q switch, the light is diffracted by the medium of the Q switch and then enters the auxiliary resonant cavity.

[0080] In the initial state, no light output signal is received. At this time, the electronic control system applies RF power to the Q switch, and the light is diffracted by the medium of the Q switch into the auxiliary resonant cavity, and resonates in the auxiliary resonant cavity along the second direction, including transmission through the first surface of the thin film polarizer along the second direction, and then propagated to the third reflector after reflection through the quarter wave plate, and then passed through the quarter wave plate again to the second surface of the thin film polarizer, and reflected on the second surface of the thin film polarizer, and then led out of the auxiliary resonant cavity and output to the heat sink for absorption, so as to realize the consumption of energy accumulated in the cavity. As an example, the quarter wave plate is adjusted to 45 degrees, and the output power of the auxiliary resonant cavity is 20w;

[0081] In the working state, after receiving the light output signal, the electric control system withdraws the RF power applied to the Q switch, so that the laser returns to the main resonant cavity and resonates along the first direction. The optical path includes the laser output from the Q switch along the first direction, transmitted through the first dichroic mirror to the frequency conversion module, and after the frequency is converted, it is reflected by the second reflector and then returned to the first dichroic mirror and reflected again. The laser is guided out of the main resonant cavity and output after being reflected by the second dichroic mirror. The pulse width is 15ns and the pulse constant power is 30w.

[0082] In this working mode, at the moment when the main resonant cavity pulse laser emits light, since the laser is in the state of outputting laser light in the initial state, the resonant cavity will quickly reach thermal equilibrium, the output laser will instantly reach a constant power, and the laser pulse will quickly reach a constant pulse energy, such as Figure 1 As shown in (b), the problem of optical power ramping and light leakage is improved.

[0083] The Q-switched laser and laser Q-switched output method with improved power ramping and light leakage provided by the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A Q-switched laser, characterized in that: It includes a first reflector, a laser crystal, a Q switch, a first dichroic mirror, a laser frequency conversion module and a second reflector arranged along a first direction, a thin-film polarizer, a quarter-wave plate and a third reflector arranged along a second direction, and a heat sink; Wherein, a main resonant cavity is formed between the first reflector and the second reflector; An auxiliary resonant cavity is formed between the first reflector and the third reflector; The heat sink is arranged at the light output end of the auxiliary resonant cavity.

2. The Q-switched laser according to claim 1, characterized in that: The second direction is the diffraction light output direction of the Q switch.

3. The Q-switched laser according to claim 2, characterized in that: The first dichroic mirror includes a first surface and a second surface, wherein the first surface faces the Q switch side, and the second surface faces the frequency conversion module side, and the second surface reflects the laser light to guide the laser light out of the main resonant cavity.

4. The Q-switched laser according to claim 3, characterized in that: The transmittance of the first surface of the first dichroic mirror to the output light of the Q switch is greater than 99.5%, and the reflectance of the second surface to the output light after frequency conversion by the frequency conversion module is greater than 99.5%.

5. The Q-switched laser according to claim 2, characterized in that: A second dichroic mirror is further arranged in the output direction of the light reflected by the first dichroic mirror, and the second dichroic mirror totally reflects the light reflected by the first dichroic mirror.

6. The Q-switched laser according to any one of claims 1 to 5, characterized in that: The frequency conversion module is selected from at least one double frequency crystal or a combination of a double frequency crystal and a triple frequency crystal.

7. The Q-switched laser according to claim 2, characterized in that: The quarter wave plate is rotatable in angle, and the thin film polarizer has a third surface and a fourth surface, the third surface faces the Q switch, and the fourth surface faces the quarter wave plate. After the laser is diffracted by the Q switch, it is transmitted through the third surface of the thin film polarizer along the second direction, and then propagates through the quarter wave plate to the third reflector for reflection, and then passes through the quarter wave plate again to the fourth surface of the thin film polarizer, is reflected on the fourth surface of the thin film polarizer, is guided out of the auxiliary resonant cavity, and is output to the heat sink for absorption.

8. The Q-switched laser according to claim 1, characterized in that: The Q-switched laser also includes a pump light source and an electronic control system, wherein the electronic control system is configured to apply or withdraw radio frequency power to the Q switch; and / or the Q switch is an acousto-optic modulator or an electro-optic modulator; and / or the laser crystal is any one of Nd:YVO4 laser crystal, Nd:YAG crystal, Nd:YLF crystal, Nd:KGW crystal, Yb:YVO4 crystal, Yb:YAG crystal, Yb:YLF crystal, Yb:KGW crystal, Pr:YLF crystal, Pr:YAP crystal, Pr:LiLuF4 crystal, Pr:LaF3 crystal, and Ti:sapphire crystal.

9. A laser Q-switched output method, characterized in that: include: Providing a laser according to any one of claims 1 to 8; When the laser is in an initial state where no light output signal is received, radio frequency power is applied to the Q switch to make the laser resonate along the second direction in the auxiliary resonant cavity, and the redundant laser is guided out of the auxiliary resonant cavity to the heat sink for absorption by the thin film polarizer; When the laser is in the working state of receiving the light output signal, the RF power is removed, the laser resonates along the first direction in the main resonant cavity, generates a pulsed laser at the moment of light output and after reaching a constant output power, it is guided out of the main resonant cavity by the first dichroic mirror to the second dichroic mirror for output.

10. The method according to claim 9, characterized in that The angle of the quarter wave plate is adjusted to change the output power of the thin film polarizer to the redundant laser. The angle adjustment range of the quarter wave plate is 0° to 45°, and the output power range of the redundant laser is 0 to 100W.

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