Q - switched laser for output optical power ramp - up and leakage light improvement and Q - switched laser output method

Abstract

The present application discloses a dual-resonator Q-switched laser. By applying or not applying radio frequency power to the Q-switch, the diffraction direction of light is changed, thereby realizing the conversion between the main resonator and the auxiliary resonator. By releasing the energy during the off-state light through the auxiliary resonator, the phenomenon of the output light energy ramping is improved, and stable output optical power is provided. Moreover, by changing the polarization direction of light to the auxiliary resonator, the damage to photosensitive materials and the damage to the equipment caused by light leakage after the off-state light are avoided, a more stable processing ability can be provided, the processing technology is optimized, and the structure is simple.

Description

Technical Field

[0001] This application belongs to the field of optical devices, and particularly relates to a Q-switched laser for improving the output power ramp-up and leakage light, and a laser Q-switching output method. Background Art

[0002] The Q-switched nanosecond laser is a laser widely used in industrial processing. By changing the Q value of the laser cavity, it can precisely control the laser pulse width and repetition frequency to meet various different processing requirements.

[0003] In Q-switched nanosecond lasers, the nanosecond green laser and nanosecond ultraviolet laser 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 for the fundamental frequency light. To enable the laser to quickly respond to external trigger signals, the pump light is 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 (ramping phenomenon) where the power / energy increases from weak to strong, that is, the process of heat release reaching equilibrium.

[0004] When the laser receives the signal to turn off the light from the external trigger signal, reducing or directly removing the radio frequency power applied to the acousto-optic Q-switch makes the laser operate in a continuous resonance mode, which may improve the power ramp-up phenomenon. However, at this time, the laser will actually output a weak leakage light when it is turned off. When processing some materials that are sensitive to laser, this leakage light will scratch the materials. For example, in the processing methods based on galvanometers or cutting heads, the imprints of the leakage light damaging the materials can be observed in the optical path trajectory between the processing areas. This not only affects the processing quality but may also cause damage to the equipment. Therefore, how to effectively solve the ramp-up phenomenon when the Q-switched nanosecond laser re-emits light after being turned off, and at the same time avoid generating leakage light, is an urgent problem to be solved in this field. Summary of the Invention

[0005] To improve the defects of the existing technology, this application proposes a Q-switched laser including a main resonant cavity and an auxiliary resonant cavity, which can achieve the improvement of the output power ramp-up and leakage light. A laser Q-switching output method is further proposed.

[0006] This application provides a Q-switched laser for improving the output power ramp-up and leakage light, including:

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

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

[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 the 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, and the second surface faces the frequency conversion module side. The second surface reflects the laser to export the laser from the main resonant cavity.

[0013] In one embodiment, the transmittance of the first surface of the first dichroic mirror for the output light of the Q-switch is above 99.5%, and the reflectivity of the second surface for the output light after frequency conversion by the frequency conversion module is above 99.5%.

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

[0015] In one embodiment, the frequency conversion module is selected from at least one second harmonic generation crystal or a combination of a second harmonic generation crystal and a third harmonic generation crystal.

[0016] In one embodiment, the quarter-wave plate is rotatable in angle. 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 being diffracted by the Q-switch, the laser transmits through the third surface of the thin film polarizer along the second direction, then propagates through the quarter-wave plate, is reflected by the third reflector, and then passes through the quarter-wave plate again to the fourth surface of the thin film polarizer, where reflection occurs on the fourth surface of the thin film polarizer, and is exported from the auxiliary resonant cavity and output to the heat sink for absorption.

[0017] In one embodiment, the Q-switched laser further includes a pump light source and an electronic control system, and the electronic 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 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.

[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 is the pulsed laser waveform diagram of the laser. (a) is the pulsed laser waveform diagram of the laser without setting an auxiliary resonant cavity in the prior art, and (b) is the pulsed laser waveform diagram of the laser in an embodiment of the present application;

[0030] Figure 2 is the structural schematic diagram of the laser in an embodiment of the present application. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present application.

[0032] When the laser in the laser is modulated by a Q-switch, taking an acousto-optic modulator as an example, in the case of only a main resonant cavity, when an RF power is applied to the acousto-optic modulator, ultrasonic waves are formed through electro-acoustic conversion to cause a periodic change in the refractive index of the modulation medium, which diffracts the incident light, causing diffraction loss, a decrease in the Q value, and the inability to form a laser oscillation. The energy accumulates in the laser crystal. When the population inversion of the upper energy level continuously accumulates and reaches the saturation value under the excitation of the pump light source, the RF signal is turned off, and the ultrasonic field is suddenly removed. The diffraction effect immediately disappears, the Q value in the cavity surges, and the laser oscillation quickly resumes. Its energy is output in the form of pulses. However, when the energy suddenly outputs in the form of pulses, the laser crystal changes from the energy storage state to the energy release state, and there is a process to reach thermal equilibrium, that is, there is a phenomenon of slow power increase, and the waveform diagram shown on the oscilloscope is as Figure 1 shown in (a). If no RF power is applied to the Q-switch in the off-light state, continuous laser is output in the resonant cavity. When the pulsed laser is output after the Q-switch works, thermal equilibrium can be quickly reached, and the ramp phenomenon is alleviated. However, the continuous laser causes light leakage, which damages the material to be processed or damages the equipment.

[0033] Based on this, the embodiment of the present application provides a Q-switched laser, including 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 the RF power can still be applied to the Q-switch in the light-off state when no pulsed laser is output, maintaining the thermal equilibrium state of the laser crystal. And by setting the auxiliary resonant cavity in the diffraction light output direction of the Q-switch, part of the energy stored in the laser crystal during the light-off state is released, helping to quickly reach the thermal equilibrium instantaneously at the moment of pulsed light output after receiving the light output signal, improving the phenomenon of the output light energy ramping up, enabling the output pulsed laser to reach the maximum pulse intensity in an extremely short time, providing a stable output optical power, as Figure 1 (b) shows; moreover, a part of the light in the auxiliary resonant cavity in the diffraction direction is output to the heat sink and absorbed, avoiding the damage to the photosensitive material and the equipment caused by the leakage of continuous laser output, and can provide a more stable processing ability, optimizing the processing technology.

[0038] In some embodiments, the main resonant cavity sequentially 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 the first direction. The laser can resonate in this resonant cavity along the first direction. It can be understood that this first direction is the connection line of the optical axes of the components in the main resonant cavity, and the laser can generate resonance in the main resonant cavity along this first direction.

[0039] In the main resonant cavity, after the laser light source is output through the laser crystal and the Q-switch, it 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 first surface to the Q-switch, and the second surface has a reflection effect on the light frequency-converted by the frequency conversion module, guiding the laser out of the main resonant cavity and outputting it. A second dichroic mirror is provided at the reflection light output end of this first dichroic mirror, and this second dichroic mirror outputs a part of the laser in 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 for the output light of the Q-switch is above 99.5%, and the reflectance of the second surface for the output light frequency-converted by the frequency conversion module is above 99.5%. In some embodiments, the coating on the first surface of the first dichroic mirror is an antireflection film for 1064 nm, having a transmittance of ≥99.5% for the wavelength of 1064 nm, and the coating on the second surface is a total reflection film for 532 nm / 355 nm, having a reflectance of ≥99.5% for the wavelength of 532 nm / 355 nm.

[0041] In a specific embodiment, the fifth surface coating of the second dichroic mirror is an antireflection film for 532 nm and a total reflection film for 355 nm. The light transmittance for light with a wavelength of 532 nm is ≥99.5%, and the light reflectance for light with a wavelength of 355 nm is 99.5%. The sixth surface coating is an antireflection film for 532 nm, and the light transmittance for light with a wavelength of 532 nm is 99.5%.

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

[0043] In a specific embodiment, the laser crystal is a Nd:YVO4 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, and the operating frequency is 21 - 110 MHz.

[0044] In some embodiments, the frequency conversion module is selected from at least one second harmonic generation crystal or a combination of a second harmonic generation crystal and a third harmonic generation crystal. For example, one second harmonic generation crystal and one third harmonic generation crystal are arranged in series, or one second harmonic generation crystal is arranged alone.

[0045] In some embodiments, the auxiliary resonant cavity is sequentially provided with a first mirror, a laser crystal, a Q-switch, a thin film polarizer, a quarter-wave plate, and a third mirror. The second direction is the diffraction light propagation direction of the Q-switch. 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 in angle. The output optical power of the auxiliary resonant cavity can be adjusted by rotating the angle of the quarter-wave plate, avoiding affecting the energy storage of the laser crystal and reducing the influence 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 redundant laser by the thin film polarizer. The angle adjustment range of the quarter-wave plate is 0° - 45°, and the output power range of the redundant laser is 0 - 100 w.

[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. 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, then propagates through the quarter-wave plate, is reflected by the third mirror, and then passes through the quarter-wave plate again to reach the fourth surface of the thin-film polarizer, where reflection occurs and it is led out of the auxiliary resonant cavity and output to the heat sink for absorption.

[0049] In some embodiments, the coating on the fourth surface of the thin-film polarizer is a polarization film layer with a wavelength of 1064 nm. The incident angle is 45 degrees to 80 degrees. The transmittance for p-polarized laser is ≥99%, and the reflectance for s-polarized laser is ≥99.8%. The wavelength range is 900 - 1300 nm. The surface coating of the third mirror is a total reflection film with a wavelength of 1064 nm, and the reflectance for light with a wavelength of 1064 nm is ≥99.5%. The heat sink is any known device with a 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 arranged on one side of the laser crystal, and its type is not particularly limited. It can output a light source with the required wavelength, such as 880 nm, 878 nm, 808 nm or other wavelengths. The pump light source can be end-pumped or side-pumped. When it is end-pumped, the pump light source is arranged on one side of the first mirror, and the first mirror is transmissive to the pump light source, and the light source is transmitted through the first mirror to reach the laser crystal. When it is side-pumped, the pump light source reaches the laser crystal from the side perpendicular to the light propagation direction (the first direction).

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

[0052] The embodiment of the present application also provides a Q-switched laser output method for improving power ramp-up and light leakage phenomena, including:

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

[0054] Among them, 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 diffraction light output direction of the Q-switch;

[0056] When the laser is in the initial state of not receiving the light output signal, radio frequency power is applied to the Q-switch, so that the laser resonates in the auxiliary resonant cavity along the second direction, and the redundant laser is led 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 radio frequency power is removed, and the laser resonates in the main resonant cavity along the first direction, generating pulsed laser at the moment of light output and outputting after reaching a constant output power.

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

[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-switching laser output method of this embodiment, since the laser is also in the state of outputting laser in the initial state of the laser, 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 reaches a constant power instantly, and the laser pulse reaches a constant pulse energy quickly, thereby solving the problem of light output power ramp-up, and also avoiding the adverse consequences such as material damage and equipment damage caused by the leakage of light output through the main resonant cavity.

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

[0062] The following provides specific embodiments to further illustrate the technical solutions of the present application.

[0063] Embodiment 1: Q-Switching Laser with Stable Power

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

[0065] Laser crystal 2: Nd:YVO4 laser crystal, with dimensions of 4 mm × 4 mm × 20 mm;

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

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

[0068] The first dichroic mirror 8: The first surface coating is an antireflection film for 1064 nm, with a light transmittance of 99.5% for light with a wavelength of 1064 nm. The coating on the second surface is a total reflection film for 532 nm / 355 nm, with a light reflectance of 99.5% for light with wavelengths of 532 nm / 355 nm. The diameter is 12.7 mm and the thickness is 3 mm;

[0069] The second dichroic mirror 9: The fifth surface coating is an antireflection film for 532 nm and a total reflection film for 355 nm, with a light transmittance of 99.5% for light with a wavelength of 532 nm and a light reflectance of 99.5% for light with a wavelength of 355 nm. The sixth surface coating is an antireflection film for 532 nm, with a light transmittance of 99.5% for light with a wavelength of 532 nm. The diameter is 12.7 mm and the thickness is 6 mm;

[0070] The frequency conversion module 10: Second harmonic generation crystal: LBO crystal, size 4 mm × 4 mm × 10 mm; Third harmonic generation crystal: LBO crystal, size 4 mm × 4 mm × 20 mm;

[0071] The second mirror 11: The surface coating is a total reflection film for 1064 nm / 532 nm, with a light reflectance of 99.5% for light with wavelengths of 1064 nm / 532 nm. The diameter is 12.7 mm and the thickness is 6 mm;

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

[0073] The quarter-wave plate 5: Made of quartz, with a diameter of 12.7 mm and a thickness of 1 mm;

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

[0075] The heat sink 7: Made of copper, with a size of 40 mm × 30 mm × 20 mm;

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

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

[0078] As Figure 2 shown, the first mirror, laser crystal, Q-switch, first dichroic mirror, frequency conversion module, and second mirror are sequentially arranged to form the main resonant cavity. The optical centers of each device are located on a straight line, and this straight line 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 arranged in sequence form an auxiliary resonant cavity. Starting from the thin-film polarizer, it is arranged in the propagation direction (the second direction) of the diffracted light of the Q-switch. When RF power is applied to the Q-switch, the light diffracts through the medium of the Q-switch and 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 diffracts through the medium of the Q-switch and enters the auxiliary resonant cavity, generating resonance in the auxiliary resonant cavity along the second direction. This includes transmitting through the first surface of the thin-film polarizer along the second direction, then propagating through the quarter-wave plate to the third reflector for reflection, and then passing through the quarter-wave plate again to the second surface of the thin-film polarizer, where reflection occurs at the second surface of the thin-film polarizer and is then exported from the auxiliary resonant cavity and output to the heat sink for absorption, achieving the consumption of the accumulated energy 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, when a light output signal is received, the electronic control system withdraws the RF power applied to the Q-switch, causing the laser to return to the main resonant cavity for resonance 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 reach the frequency conversion module, and after frequency conversion, reflected by the second reflector and then reflected again when returning to the first dichroic mirror. The laser is then exported from 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 pulsed laser in the main resonant cavity outputs light, since the laser is in the state of outputting laser in the initial state, the resonant cavity will quickly reach thermal equilibrium, the output laser will instantaneously reach a constant power, and the laser pulse will quickly reach a constant pulse energy, as Figure 1 (b) shows, thereby improving the problems of light output power ramp-up and light leakage.

[0083] The above has introduced in detail the Q-switched laser and the laser Q-switching output method for improving power ramp-up and light leakage provided by this application. Specific examples are used in this article to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application; at the same time, for those skilled in the art, according to the idea of this application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to this 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 second direction is the diffraction light output direction of the Q-switch; The heat sink is arranged at the reflection light output end of the thin film polarizer.

2. The Q-switched laser according to claim 1, wherein The first dichroic mirror includes a first surface and a second surface. The first surface faces the side of the Q-switch, and the second surface faces the side of the frequency conversion module. The second surface reflects the laser to export the laser out of the main resonant cavity.

3. The Q-switched laser according to claim 2, characterized in that, The transmittance of the first surface of the first dichroic mirror to the output light of the Q-switch is more than 99.5%, and the reflectivity of the second surface to the output light after frequency conversion by the frequency conversion module is more than 99.5%.

4. The Q-switching laser according to claim 1, characterized in that, The quarter-wave plate is angle-rotatable. 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 being diffracted by the Q-switch, the laser transmits along the second direction through the third surface of the thin film polarizer, then propagates through the quarter-wave plate to the third reflector and is reflected, then passes through the quarter-wave plate again to the fourth surface of the thin film polarizer, and is reflected at the fourth surface of the thin film polarizer, is exported from the auxiliary resonant cavity, and is output to the heat sink for absorption.

5. The Q-switched laser according to claim 1, wherein The Q-switched laser further includes a pump light source and an electric control system, and the electric 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.

6. The Q-switched laser according to claim 1, wherein A second dichroic mirror is further arranged in the output direction of the reflected light of the first dichroic mirror, and the second dichroic mirror totally reflects the reflected light of the first dichroic mirror.

7. The Q-switched laser according to any one of claims 1-6, characterized in that The frequency conversion module is selected from at least one second harmonic generation crystal or a combination of a second harmonic generation crystal and a third harmonic generation crystal.

8. A Q-switching output method of laser, characterized in that, It includes: Providing the laser according to any one of claims 1-5; When the laser is in an initial state where no light output signal is received, applying radio frequency power to the Q-switch to cause the laser to resonate along the second direction in the auxiliary resonant cavity, and the redundant laser is exported from the auxiliary resonant cavity to the heat sink for absorption by the thin film polarizer; When the laser is in an operating state where a light output signal is received, withdrawing the radio frequency power, the laser resonates along the first direction in the main resonant cavity, generates pulsed laser at the moment of light output, and after reaching a constant output power, is exported from the main resonant cavity by the first dichroic mirror for output.

9. The method according to claim 8, wherein A second dichroic mirror is also provided in the output direction of the light reflected by the first dichroic mirror, and the second dichroic mirror totally reflects the reflected light of the first dichroic mirror.

10. The method according to claim 9, characterized in that The frequency conversion module is selected from at least one second harmonic generation crystal or a combination of a second harmonic generation crystal and a third harmonic generation crystal.

11. The method according to claim 9 or 10, characterized in that, Adjust the angle of the quarter-wave plate to change the output power of the redundant laser by the thin-film polarizer. 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 100 w.

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