High-power nanosecond laser with adjustable time-domain double-pulse delay

Abstract

The utility model provides a time-domain double-pulse delay-adjustable high-power nanosecond laser, which comprises a passive Q-switched resonant cavity, a single-lamp double-rod amplification module, a first single-lamp single-rod amplification module, a second single-lamp single-rod amplification module, a light beam collimation module, a half-wave plate and a delay light path control module which are sequentially arranged, the centers of the single-lamp double-rod amplification module, the first single-lamp single-rod amplification module, the second single-lamp single-rod amplification module, the light beam collimation module, the half-wave plate and the delay light path control module are arranged on the same horizontal line. According to the utility model, laser pulse output with adjustable time-domain double-pulse laser delay time is realized, intelligent regulation and control of the double-pulse laser delay time are effectively realized, and the ubiquitous problems of low energy utilization rate and generation of plasma shielding effect in traditional laser shock peening are improved.

Description

Technical Field

[0001] This utility model relates to the technical field of nanosecond lasers, and in particular to a high-power nanosecond laser with adjustable time-domain dual-pulse delay. Background Technology

[0002] Laser shock peening (LSP) is a surface strengthening technique that uses a laser beam to modify the surface of metallic materials. LSP employs a short-pulse (nanosecond level) high-peak-power (GW / cm²) laser beam that penetrates a transparent confinement layer onto an absorption layer on the material surface. The absorption layer absorbs energy and ionizes within a very short time to form plasma. Under the influence of the confinement layer, the plasma continuously accumulates, forming a GPa-level plasma shock wave that propagates into the metal. When the shock wave pressure exceeds the material's yield strength, plastic deformation occurs on the material surface, leading to an increase in lattice dislocation density, grain refinement, and other microstructural changes, ultimately forming a residual stress layer 0.5-2 mm deep on the material surface. LSP can effectively improve the fatigue performance of materials and extend their service life. The temporal characteristics of the shock wave determine the actual strengthening effect on the target material. In practical applications, LSP faces a technical bottleneck of low laser energy utilization, which directly restricts the effective improvement of the plasma shock wave intensity. When a high-power laser irradiates a material surface, it triggers a plasma formation process on a nanosecond timescale, and this plasma layer has specific thickness distribution characteristics. It is worth noting that when the plasma density exceeds a critical threshold, a significant plasma shielding effect is triggered—this high-density plasma strongly reflects and absorbs subsequent laser beams, hindering the efficient transmission of laser energy to the material surface, thus making it difficult to maintain a stable plasma shock wave intensity. Current techniques attempting to increase power density by reducing the spot size, while theoretically enhancing shock wave intensity, lead to practical problems such as reduced processing spot area and decreased energy distribution uniformity, ultimately severely limiting processing efficiency and the stability of the strengthening effect. Delayed dual-pulse lasers can modify the laser energy deposition path, regulate the evolution of the laser-induced plasma shock wave and the subsequent laser-plasma interaction process, increasing the plasma duration and intensity, ultimately achieving better strengthening efficiency and effect.

[0003] To achieve stable high peak power laser output, the commonly used amplification techniques are CPA (chirped-pulse amplification), OPCPA (optical parametric chirped-pulse amplification), and MOPA (master oscillator power amplifier). CPA, as an early and revolutionary ultrashort pulse laser amplification method, can achieve high peak power outputs from terawatts (TW) to petawatts (PW). However, its drawbacks are also significant. CPA systems require precise control of the pulse's phase and timing characteristics, including the use of complex grating pairs to broaden and compress the pulse, which increases system complexity and cost. In recent years, MOPA technology has become the mainstream solution for high-energy all-solid-state lasers due to its significant advantages. This technology uses a stable, low-power, single-frequency master oscillator combined with a high-gain amplification stage, ensuring extremely high peak power output while also featuring a simple system structure, convenient operation and maintenance, excellent output beam quality, high frequency stability, and modular design that facilitates power expansion and effectively suppresses nonlinear effects. Compared to the complex OPCPA technology, MOPA does not require stringent phase matching conditions, has low temperature sensitivity, and operates over a wider wavelength range, making it widely used in industrial processing, scientific research, and other fields. Utility Model Content

[0004] To address the technical problems of low laser energy utilization and plasma shielding effect in traditional laser shock peening, this invention proposes a high-power nanosecond laser with adjustable time-domain dual-pulse delay. By intelligently controlling the delay time of the dual-pulse laser, the laser energy deposition path can be changed, ultimately achieving a better laser shock peening effect.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows: A high-power nanosecond laser with adjustable time-domain dual-pulse delay includes a passively Q-switched resonant cavity, a single-lamp dual-rod amplification module, a first single-lamp single-rod amplification module, a second single-lamp single-rod amplification module, a beam collimation module, a half-wave plate, and a delay optical path control module arranged sequentially. The centers of the single-lamp dual-rod amplification module, the first single-lamp single-rod amplification module, the second single-lamp single-rod amplification module, the beam collimation module, the half-wave plate, and the delay optical path control module are arranged on the same horizontal line.

[0006] The passively Q-switched resonant cavity generates seed light, which undergoes four stages of power amplification through a single-lamp dual-rod amplification module, a first single-lamp single-rod amplification module, and a second single-lamp single-rod amplification module. It then enters a beam collimation module to correct the wavefront distortion accumulated during the power amplification process, compressing the beam divergence angle to the diffraction limit and generating a high-energy, high-power laser pulse. A rotating half-wave plate dynamically adjusts the light energy distribution between the normal and delayed optical paths. The delayed optical path control module alters the laser energy deposition path by adjusting the pulse delay time Δt between the normal and delayed optical paths, thereby controlling the evolution of the laser-induced plasma shock wave and the subsequent laser-plasma interaction process.

[0007] Preferably, a quartz rotor is provided between the first single-lamp single-rod amplification module and the second single-lamp single-rod amplification module. The quartz rotor performs thermal effect compensation, corrects the thermal lensing effect generated by the first single-lamp single-rod amplification module, and maintains the beam quality.

[0008] Preferably, an optical isolator is provided between the passive Q-switched resonant cavity and the single-lamp dual-rod amplification module, with the center point of the optical isolator aligned with the center point of the passive Q-switched resonant cavity and the single-lamp dual-rod amplification module on the same horizontal line; a first beam expander is provided between the optical isolator and the single-lamp dual-rod amplification module, with the center point of the first beam expander being aligned with the center point of the optical isolator and the single-lamp dual-rod amplification module on the same horizontal line; a second beam expander is provided between the single-lamp dual-rod amplification module and the first single-lamp single-rod amplification module, with the center point of the second beam expander being aligned with the center point of the single-lamp dual-rod amplification module and the first single-lamp single-rod amplification module on the same horizontal line; and a third beam expander is provided between the first single-lamp single-rod amplification module and the quartz rotor, with the center point of the third beam expander being aligned with the center point of the first single-lamp single-rod amplification module and the quartz rotor on the same horizontal line.

[0009] Preferably, the single-lamp dual-rod amplification module, the first single-lamp single-rod amplification module, and the second single-lamp single-rod amplification module are all implemented using neodymium-doped yttrium aluminum garnet laser crystal rods;

[0010] The quartz rotor is a quartz crystal.

[0011] Preferably, the first beam expander module, the second beam expander module, and the third beam expander module each include a first negative lens and a first positive lens arranged sequentially. The center points of the first negative lens and the first positive lens are set on the same horizontal line as the center point of the single-lamp dual-rod magnification module, and the distance between the first negative lens and the first positive lens is equal to the difference in focal length between the first negative lens and the first positive lens.

[0012] Preferably, the passively Q-switched resonant cavity includes a 0° total internal reflection mirror, an LD side-pumping module, a passively Q-switched switch, a fifth polarization beam splitter, a pinhole, and an output mirror arranged sequentially. The center points of the 0° total internal reflection mirror, the LD side-pumping module, the passively Q-switched switch, the fifth polarization beam splitter, the pinhole, and the output mirror are on the same horizontal line. The 0° total internal reflection mirror and the output mirror form a resonant cavity. Under the action of the LD side-pumping module, the gain medium continuously accumulates the number of inverted particles. At this time, the saturable absorber maintains a high-loss state to suppress laser oscillation. When the stored energy reaches the threshold, the absorber suddenly saturates and becomes transparent. The number of photons in the resonant cavity increases avalanche, forming a nanosecond-level giant pulse. The passively Q-switched switch enables the resonant cavity to output a larger seed light. The fifth polarization beam splitter and the pinhole work together to ensure linear polarization and fundamental mode output. The high peak power and narrow pulse width seed light is coupled out through the output mirror (1-6).

[0013] Preferably, the beam collimation module includes a second positive lens and a second negative lens arranged in sequence, with the center points of the second positive lens and the second negative lens set on the same horizontal line. The second positive lens converts the diverging beam output by the second single-lamp single-rod amplification module into a converging beam, and the second negative lens readjusts the converging beam into collimated parallel light. The distance between the second positive lens and the second negative lens is the sum of the focal lengths of the positive and negative lenses.

[0014] Preferably, the delay optical path control module includes a third polarization beam splitter, a fourth polarization beam splitter, and a reflection component. The center points of the half-wave plate, the third polarization beam splitter, and the fourth polarization beam splitter are set on the same horizontal line, and the reflection component is set on the delay optical path between the third polarization beam splitter and the fourth polarization beam splitter.

[0015] Preferably, the reflecting component includes a first 45° total reflection mirror and a second 45° total reflection mirror. The first 45° total reflection mirror is disposed in the reflected light path of the third polarizing beam splitter. The center points of the first 45° total reflection mirror and the second 45° total reflection mirror are disposed on the same horizontal line. The fourth polarizing beam splitter is disposed in the reflected light path of the second 45° total reflection mirror.

[0016] Preferably, the third polarizing beam splitter and the first 45° total reflection mirror are both disposed on the first electric displacement platform, the first 45° total reflection mirror is disposed on the slider of the first electric displacement platform, the fourth polarizing beam splitter and the second 45° total reflection mirror are both disposed on the first electric displacement platform, and the second 45° total reflection mirror is disposed on the slider of the second electric displacement platform.

[0017] The third polarization beam splitter receives linearly polarized light from the half-wave plate. It has high transmittance for P-polarized light, allowing it to directly enter the normal optical path. For S-polarized light, it has high reflectivity, deflecting it 90° before it enters the delayed optical path L1. The light then passes through the first 45° total reflection mirror into the delayed optical path L2, and through the second 45° total reflection mirror into the delayed optical path L3. After being re-beamed with the P-polarized light by the fourth polarization beam splitter, a time-domain double pulse is formed. The S-polarized light, through the first and second 45° total reflection mirrors, introduces an optical path difference ΔL = L1 + L2 + L3 - L4. Based on this optical path difference, the delay time of the double pulse laser is adjustable within a certain range.

[0018] The pulse delay time Δt satisfies: Δt=(L1+L2+L3-L4) / c; where the adjustment range of the pulse delay time Δt is 0-10ns, L4 is the normal optical path length, L1+L2+L3 is the delayed optical path length, and c is the speed of light;

[0019] Based on the preset pulse delay time Δt, the optical path difference ΔL = c·Δt is calculated, and the displacement between the first 45° total reflection mirror and the third polarization beam splitter, and between the second 45° total reflection mirror and the fourth polarization beam splitter, is determined to be ΔL / 2.

[0020] By rotating the half-wave plate to adjust the energy ratio of the P-polarized and S-polarized light paths in the delayed optical path control module, the relationship between the rotation angle θ of the half-wave plate and the energy ratio is as follows:

[0021] Where φ0 is the initial phase shift, and the ratio of P-polarized light to S-polarized light is precisely adjusted from 1:1 to 10:1 by controlling the rotation angle θ; E1 ​​represents the energy of P-polarized light and E2 represents the energy of S-polarized light.

[0022] Compared with existing technologies, the advantages of this invention are as follows: This invention has a simple structure and good stability. It utilizes MOPA technology to generate high peak power laser light, combined with intelligent control of the delayed laser path control module, solving the problem of reduced processing efficiency caused by the plasma shielding effect. It enables the laser to fully utilize its energy to generate plasma shock waves under the same input energy and spot size, thereby significantly improving the efficiency and effect of laser shock enhancement. This invention achieves adjustable time-domain dual-pulse laser output, effectively realizing intelligent control of the dual-pulse laser delay time, and improving upon the problems of low energy utilization and plasma shielding effect commonly found in traditional laser shock enhancement. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of this utility model.

[0025] Figure 2 for Figure 1 The diagram shows the structure of a passively Q-switched resonant cavity.

[0026] Figure 3 for Figure 1 The diagram shows the structure of the beam expander module.

[0027] Figure 4 for Figure 1 The schematic diagram of the beam collimation module shown is as follows.

[0028] Figure 5 for Figure 1 The diagram shows the structure of the delayed optical path control module.

[0029] In the diagram, 1 is a passively Q-switched resonant cavity, 2 is an optical isolator, 3 is the first beam expander module, 4 is a single-lamp dual-rod amplification module, 5 is the second beam expander module, 6 is the first single-lamp single-rod amplification module, 7 is the third beam expander module, 8 is a quartz rotor, 9 is the second single-lamp single-rod amplification module, 10 is a beam collimation module, 11 is a half-wave plate, 12 is a delay optical path control module, 1-1 is a 0° total reflection mirror, 1-2 is an LD side pump module, 1-3 is a passively Q-switched switch, 1-4 is a polarization beam splitter, 1-5 is a pinhole, 1-6 is an output mirror, 3-1 is a negative lens, 3-2 is a positive lens, 10-1 is a positive lens, 10-2 is a negative lens, 12-1 is the third polarization beam splitter, 12-2 is the fourth polarization beam splitter, 12-3 is the first 45° total reflection mirror, and 12-4 is the second 45° total reflection mirror. L1, L2, and L3 are the lengths of the delayed optical path, and L4 is the length of the reference optical path. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] like Figure 1 As shown, a time-domain dual-pulse delay-tunable high-power nanosecond laser includes a passively Q-switched resonant cavity 1, a single-lamp dual-rod amplification module 4, a first single-lamp single-rod amplification module 6, a quartz rotor 8, a second single-lamp single-rod amplification module 9, a beam collimation module 10, a half-wave plate 11, and a delay optical path control module 12 arranged sequentially. All optical components of the single-lamp dual-rod amplification module 4, the first single-lamp single-rod amplification module 6, the second single-lamp single-rod amplification module 9, the beam collimation module 10, the half-wave plate 11, and the delay optical path control module 12 are arranged on the same horizontal line to realize the transmission of seed light. The passively Q-switched resonant cavity 1 generates seed light, which undergoes four stages of power amplification through the single-lamp dual-rod amplification module 4, the first single-lamp single-rod amplification module 6, and the second single-lamp single-rod amplification module 9, and then enters the beam collimation module 10 to generate a high-energy, high-power laser pulse with high beam quality. The delayed optical path control module 12 divides the laser pulse into a normal optical path and a delayed optical path. By adjusting the pulse delay time Δt, it changes the laser energy deposition path, regulates the evolution of the laser-induced plasma shock wave and the subsequent interaction process between the laser and the plasma, and dynamically adjusts the energy distribution of the two optical paths by rotating the half-wave plate 11.

[0032] The primary function of the passively Q-switched resonant cavity 1 is to achieve dynamic output of the seed light through the nonlinear characteristics of the saturable absorber. The single-lamp dual-rod amplification module 4 serves as the first-stage amplification; the dual-rod design makes the pumping more uniform, improves energy extraction efficiency, and amplifies more fully. The first single-lamp single-rod amplification module 6 and the second single-lamp single-rod amplification module 9 serve as the second and third-stage amplification, respectively, progressively increasing the pulse energy. The main function of the beam collimation module 10 is to correct the wavefront distortion accumulated during the amplification process of the second single-lamp single-rod amplification module 9, compressing the beam divergence angle to the diffraction limit. The delayed laser path control module 12 primarily functions to change the laser energy deposition path by adjusting the pulse delay time Δt, controlling the evolution of the laser-induced plasma shock wave and the subsequent laser-plasma interaction process, improving energy deposition efficiency, plasma duration and intensity, and weakening the influence of the plasma shielding effect.

[0033] The single-lamp dual-rod amplification module 4, the first single-lamp single-rod amplification module 6, and the second single-lamp single-rod amplification module 9 are implemented using neodymium-doped yttrium aluminum garnet (Nd:YAG) laser crystal rods.

[0034] A quartz rotor 8 is provided between the first single-lamp single-rod amplification module 6 and the second single-lamp single-rod amplification module 9. The quartz rotor 8 performs thermal effect compensation. By rotating, it can improve the thermal lensing effect, correct the thermal lensing effect (i.e., asymmetric thermal distortion) generated by the first single-lamp single-rod amplification module 6 in the preceding stage, and maintain beam quality. The quartz rotor 8 is a quartz crystal.

[0035] An optical isolator 2 is provided between the passive Q-switched resonant cavity 1 and the single-lamp dual-rod amplification module 4. The center point of the optical isolator 2 is aligned with the center points of the passive Q-switched resonant cavity 1 and the single-lamp dual-rod amplification module 4 on the same horizontal line. The function of the optical isolator 2 is to prevent back-transmitted light from damaging the passive Q-switched resonant cavity 1, ensuring unidirectional transmission of the emitted seed light. The optical isolator 2 consists of a first polarization beamsplitter, a Faraday rotator, and a second polarization beamsplitter arranged sequentially. The center points of the first polarization beamsplitter, the Faraday rotator, and the second polarization beamsplitter are aligned with the center point of the passive Q-switched resonant cavity 1 on the same horizontal line. The functions of the first polarization beamsplitter, the Faraday rotator, and the second polarization beamsplitter are respectively to prevent back-transmitted light from damaging the passive Q-switched resonant cavity 1, ensuring unidirectional transmission.

[0036] A first beam expander module 3 is provided between the optical isolator 2 and the single-lamp dual-rod amplification module 4. The center point of the first beam expander module 3 is aligned with the center points of the optical isolator 2 and the single-lamp dual-rod amplification module 4 on the same horizontal line. A second beam expander module 5 is provided between the single-lamp dual-rod amplification module 4 and the first single-lamp single-rod amplification module 6. The center point of the second beam expander module 5 is aligned with the center points of the single-lamp dual-rod amplification module 4 and the first single-lamp single-rod amplification module 6 on the same horizontal line. A third beam expander module 7 is provided between the first single-lamp single-rod amplification module 6 and the quartz rotor 8. The center point of the third beam expander module 7 is aligned with the center points of the first single-lamp single-rod amplification module 6 and the quartz rotor 8 on the same horizontal line. The functions of the first beam expander module 3, the second beam expander module 5, and the third beam expander module 7 are all to match the crystal aperture of the preamplifier module, avoid optical damage, and ensure that the beam covers the effective area of ​​the gain medium.

[0037] like Figure 3As shown, the first beam expander module 3, the second beam expander module 5, and the third beam expander module 7 each include a first negative lens 3-1 and a first positive lens 3-2 arranged sequentially. The center points of the first negative lens 3-1 and the first positive lens 3-2 are on the same horizontal line as the center point of the single-lamp dual-rod amplification module 4. The lenses are positioned such that the distance between the first negative lens 3-1 and the first positive lens 3-2 is equal to the difference in their focal lengths. The first negative lens 3-1 diverges the incident parallel beam, while the first positive lens 3-2 converts the diverged beam from the first negative lens 3-1 back into parallel light, while simultaneously amplifying the beam diameter. The first beam expander module 3 gently expands the seed beam, preparing it for the high-power amplification of the subsequent single-lamp dual-rod amplification module 4. The expanded beam enters the single-lamp dual-rod amplification module 4, where the laser first experiences a significant energy boost. The dual-rod structure design saves space and effectively suppresses the thermal lensing effect, providing a stable first-order gain for the system. The second beam expander module 5 gently expands the seed beam to match the crystal aperture of the first single-lamp single-rod amplification module 6, avoiding optical damage that reduces power density after beam expansion, and amplifying the energy a second time. The beam then enters the first single-lamp single-rod amplification module 6, where the focus is on further energy extraction. The third beam expander module 7 maintains beam quality throughout this process, preventing nonlinear effects caused by excessive power density.

[0038] Among them, such as Figure 2 As shown, the passively Q-switched resonant cavity 1 includes a 0° total internal reflection mirror 1-1, an LD side-pumping module 1-2, a passively Q-switched switch 1-3, a fifth polarization beam splitter 1-4, a pinhole 1-5, and an output mirror 1-6 arranged sequentially. The center points of the 0° total internal reflection mirror 1-1, the LD side-pumping module 1-2, the passively Q-switched switch 1-3, the fifth polarization beam splitter 1-4, the pinhole 1-5, and the output mirror 1-6 are on the same horizontal line. The seed light is output from the output mirror 1-6 and enters the optical isolator 2. The passively Q-switched resonant cavity 1 uses the 0° total internal reflection mirror 1-1 and the output mirror 1-6 to form a resonant cavity. Under the action of the LD side-pumping module 1-2, the gain medium continuously accumulates the number of inverted particles. At this time, the saturable absorber maintains a high-loss state to suppress laser oscillation. When the stored energy reaches the threshold, the absorber suddenly saturates and becomes transparent, and the number of photons in the cavity increases avalanche, forming a nanosecond-level giant pulse. Finally, the high peak power (10) is coupled out through the output mirror 1-6. 5 -10 7High-quality seed light with narrow pulse width (5-20ns) is produced. The LD side-pump module 1-2 uses LD pumping, and the passive Q-switching switch 1-3 enables the resonant cavity to output a larger seed light, laying the foundation for subsequent amplification. The fifth polarization beam splitter 1-4 and the aperture 1-5 work together to ensure linear polarization and fundamental mode output, providing an ideal laser source for the subsequent amplification system. The light reflected by the fifth polarization beam splitter 1-4 is useless. The polarization beam splitter 1-4 and the aperture 1-5 work together to ensure that the light output from the passive Q-switched resonant cavity 1 is linearly polarized and contains the fundamental mode, providing an ideal seed light for the subsequent amplification system. The seed light enters the optical isolator 2 from the passive Q-switched resonant cavity 1. The main function of the optical isolator 2 is to block the reverse-propagating light using the polarization principle, ensuring that the incident light passes through unidirectionally and protecting the passive Q-switched resonant cavity 1.

[0039] The main functions of the first beam expander module 3, the second beam expander module 5, and the third beam expander module 7 are to achieve precise matching of beam parameters with the amplification link: through multi-stage gradient beam expansion, the seed light is gradually amplified to match the crystal aperture of the single-lamp dual-rod amplification module 4, the first single-lamp single-rod amplification module 6, and the second single-lamp single-rod amplification module 9. This reduces power density to protect optical components while ensuring sufficient overlap between the beam and the gain region. The quartz rotor 8 performs thermal effect compensation, correcting the thermal lensing effect generated by the pre-amplification module and maintaining beam quality. The second single-lamp single-rod amplification module 9 performs final stage energy boosting. At this point, the precise control of the beam expander modules ensures that the amplification process is always carried out under optimal beam parameters, providing ideal optical input for the delay optical path control module.

[0040] like Figure 4 As shown, the beam collimation module 10 includes a second positive lens 10-1 and a second negative lens 10-2 arranged sequentially, with their center points aligned on the same horizontal line. The second positive lens 10-1 converts the diverging beam (due to thermal lensing or natural divergence) output from the pre-amplification module into a converging beam, while the second negative lens 10-2 readjusts the converging beam formed by the second positive lens 10-1 into parallel light (collimated state). The distance between the second positive lens 10-1 and the second negative lens 10-2 is the sum of the focal lengths of the positive and negative lenses, converting the diverging beam output from the pre-amplification module 9 into parallel light. The main function of the beam collimation module 10 is to correct the wavefront distortion accumulated during the amplification process of the pre-amplification module 9, compress the beam divergence angle to the diffraction limit, and the collimated beam characteristics directly affect the laser shock enhancement effect.

[0041] like Figure 5As shown, the delayed optical path control module 12 includes a third polarization beam splitter 12-1, a fourth polarization beam splitter 12-2, a first 45° total reflection mirror 12-3, and a second 45° total reflection mirror 12-4. The center points of the half-wave plate 11, the third polarization beam splitter 12-1, and the fourth polarization beam splitter 12-2 are set on the same horizontal line. The first 45° total reflection mirror 12-3 is set on the reflected optical path of the third polarization beam splitter 12-1. The center points of the first 45° total reflection mirror 12-3 and the second 45° total reflection mirror 12-4 are set on the same horizontal line. The fourth polarization beam splitter 12-2 is set on the reflected optical path of the second 45° total reflection mirror 12-4. The first 45° total reflection mirror 12-3 and the second 45° total reflection mirror 12-4 reflect the light from the third polarization beam splitter 12-1 twice perpendicularly before it enters the fourth polarization beam splitter 12-2. The fourth polarization beam splitter 12-2 combines the P-polarized and S-polarized light to achieve delayed output. The third polarization beam splitter 12-1, the fourth polarization beam splitter 12-2, the first 45° total reflection mirror 12-3, and the second 45° total reflection mirror 12-4 are all mounted on the intelligent potential moving platform. The third polarization beam splitter 12-1 receives linearly polarized light from the preceding half-wave plate 11. The third polarization beam splitter 12-1 has high transmittance for P-polarized light, allowing it to directly enter optical path L4. The third polarization beam splitter 12-1 has high reflectivity for S-polarized light, deflecting it by 90° before it enters the delayed optical path L1. The delayed optical path L1 is perpendicular to optical path L4. The S-polarized light is introduced by an optical path difference ΔL = L1 + L2 + L3 - L4 via the adjustable mirror group, namely the first 45° total reflection mirror 12-3 and the second 45° total reflection mirror 12-4. Specifically, it enters the delayed optical path L2 through the first 45° total reflection mirror 12-3 and the delayed optical path L3 through the second 45° total reflection mirror 12-4. After being re-beamed with the P-polarized light by the fourth polarization beam splitter 12-2, a time-domain double pulse is formed. By rotating the half-wave plate 11, the incident polarization direction is changed, dynamically adjusting the energy distribution of the two optical paths. The intelligent electrical displacement platform can precisely control the positions of the third polarization beam splitter 12-1, the first 45° total reflection mirror 12-3, the second 45° total reflection mirror 12-4, and the fourth polarization beam splitter 12-2, achieving adjustable dual-pulse laser delay time within a certain range based on the optical path difference. The pulse delay time Δt achieved by the delay optical path control module 12 satisfies:

[0042] Δt=(L1+L2+L3-L4) / c

[0043] The pulse delay time Δt is adjustable from 0 to 10 ns, L4 is the reference optical path length, L1+L2+L3 is the delay optical path length, and c is the speed of light. The delay time is continuously adjustable by adjusting the delay optical path length using an intelligent electric displacement platform. The high-precision motor-driven intelligent electric displacement platform has a positioning accuracy better than 20 μm to meet the requirements for precise control of the dual-pulse laser delay time. Specifically, the reference optical path length L4 and the delay optical path length L2 are equal, so it is necessary to adjust the distance between the third polarization beam splitter 12-1 and the first 45° total reflection mirror 12-3, as well as the distance between the fourth polarization beam splitter 12-2 and the second 45° total reflection mirror 12-4. The third polarization beam splitter 12-1 and the first 45° total reflection mirror 12-3 are both mounted on the first electric displacement platform. The fourth polarization beam splitter 12-2 and the second 45° total reflection mirror 12-4 are both mounted on the second electric displacement platform. The first 45° total reflection mirror 12-3 is mounted on a slider on the first electric displacement platform, and the second 45° total reflection mirror 12-4 is mounted on a corresponding slider on the second electric displacement platform. After the user inputs the target pulse delay time Δt, the software of the electric displacement platform automatically calculates the optical path difference according to the formula ΔL=c·Δt. This determines that the displacement of each total reflection mirror relative to its respective polarization beam splitter on the electric displacement platform is ΔL / 2. The electric displacement platform drives the slider according to the displacement to move the first 45° total reflection mirror 12-3 and the second 45° total reflection mirror 12-4 to their corresponding positions. The first 45° total reflection mirror 12-3 and the second 45° total reflection mirror 12-4 are always on the same horizontal line, realizing automatic adjustment of the dual-pulse laser delay time. The model of the intelligent electric displacement platform is PA1000. By adjusting the pulse delay time Δt to change the laser energy deposition path, the evolution of the laser-induced plasma shock wave and the subsequent laser-plasma interaction process can be controlled, thereby improving energy deposition efficiency, plasma duration and intensity, and weakening the influence of plasma shielding effect.

[0044] The energy ratio of the P-polarized light and S-polarized light in the delayed optical path control module 12 is adjusted by rotating the half-wave plate 11. The relationship between the rotation angle θ of the half-wave plate 11 and the energy ratio is as follows:

[0045]

[0046] Where φ0 is the initial phase shift, and the ratio of P-polarized light to S-polarized light is precisely adjusted from 1:1 to 10:1 by controlling the rotation angle θ. E1 represents the energy of P-polarized light, and E2 represents the energy of S-polarized light.

[0047] In summary, this invention proposes a high-power nanosecond laser with adjustable time-domain dual-pulse delay. Based on the MOPA architecture, it integrates a passive Q-switched resonant cavity, a multi-stage amplification module, and a delay optical path control module, realizing dynamic distribution of dual-pulse delay and energy, effectively improving the laser shock enhancement effect. The system has both high stability and programmability, and is suitable for the field of precision material processing.

[0048] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A high-power nanosecond laser with adjustable time-domain dual-pulse delay, characterized in that, The passive Q-switched resonant cavity (1), single-lamp dual-rod amplification module (4), first single-lamp single-rod amplification module (6), second single-lamp single-rod amplification module (9), beam collimation module (10), half-wave plate (11), and delay optical path control module (12) are arranged sequentially. The centers of the single-lamp dual-rod amplification module (4), first single-lamp single-rod amplification module (6), second single-lamp single-rod amplification module (9), beam collimation module (10), half-wave plate (11), and delay optical path control module (12) are set on the same horizontal line. The passively Q-switched resonant cavity (1) generates seed light, which undergoes four stages of power amplification through a single-lamp dual-rod amplification module (4), a first single-lamp single-rod amplification module (6), and a second single-lamp single-rod amplification module (9). The seed light then enters a beam collimation module (10) to correct the wavefront distortion accumulated during the power amplification process, compressing the beam divergence angle to the diffraction limit and generating a high-energy, high-power laser pulse. A half-wave plate (11) is rotated to dynamically adjust the light energy distribution between the normal optical path and the delayed optical path. The delayed optical path control module (12) adjusts the pulse delay time between the normal optical path and the delayed optical path. Δt By altering the laser energy deposition path, the evolution of laser-induced plasma shock waves and subsequent laser-plasma interaction processes can be controlled.

2. The time-domain dual-pulse delay-tunable high-power nanosecond laser according to claim 1, characterized in that, A quartz rotor (8) is provided between the first single-lamp single-rod amplification module (6) and the second single-lamp single-rod amplification module (9). The quartz rotor (8) performs thermal effect compensation, corrects the thermal lensing effect generated by the first single-lamp single-rod amplification module (6), and maintains the beam quality.

3. The time-domain dual-pulse delay-adjustable high-power nanosecond laser according to claim 2, characterized in that, An optical isolator (2) is provided between the passive Q-switched resonant cavity (1) and the single-lamp dual-rod amplification module (4). The center point of the optical isolator (2) is set on the same horizontal line as the center point of the passive Q-switched resonant cavity (1) and the single-lamp dual-rod amplification module (4). A first beam expander (3) is provided between the optical isolator (2) and the single-lamp dual-rod amplification module (4). The center point of the first beam expander (3) is set on the same horizontal line as the center point of the optical isolator (2) and the single-lamp dual-rod amplification module (4). A second beam expander (5) is provided between the single-lamp dual-rod amplification module (4) and the first single-lamp single-rod amplification module (6). The center point of the second beam expander (5) is set on the same horizontal line as the center point of the single-lamp dual-rod amplification module (4) and the first single-lamp single-rod amplification module (6). A third beam expander (7) is provided between the first single-lamp single-rod amplification module (6) and the quartz rotor (8). The center point of the third beam expander (7) is set on the same horizontal line as the center point of the first single-lamp single-rod amplification module (6) and the quartz rotor (8).

4. The time-domain dual-pulse delay-adjustable high-power nanosecond laser according to claim 3, characterized in that, The single-lamp dual-rod amplification module (4), the first single-lamp single-rod amplification module (6), and the second single-lamp single-rod amplification module (9) are all implemented using neodymium-doped yttrium aluminum garnet laser crystal rods; The quartz rotor (8) is a quartz crystal.

5. The time-domain dual-pulse delay-tunable high-power nanosecond laser according to claim 3 or 4, characterized in that, The first beam expander module (3), the second beam expander module (5) and the third beam expander module (7) each include a first negative lens (3-1) and a first positive lens (3-2) arranged in sequence. The center point of the first negative lens (3-1) and the first positive lens (3-2) is set on the same horizontal line as the center point of the single-lamp dual-rod magnification module (4). The distance between the first negative lens (3-1) and the first positive lens (3-2) is equal to the difference in focal length between the first negative lens (3-1) and the first positive lens (3-2).

6. The time-domain dual-pulse delay-tunable high-power nanosecond laser according to any one of claims 1-4, characterized in that, The passively Q-switched resonant cavity (1) includes a 0° total reflection mirror (1-1), an LD side pump module (1-2), a passively Q-switched switch (1-3), a fifth polarization beam splitter (1-4), a pinhole (1-5), and an output mirror (1-6) arranged sequentially. The center points of the 0° total reflection mirror (1-1), the LD side pump module (1-2), the passively Q-switched switch (1-3), the fifth polarization beam splitter (1-4), the pinhole (1-5), and the output mirror (1-6) are on the same horizontal line. The 0° total reflection mirror (1-1) and the output mirror (1-6) constitute a... In the resonant cavity, under the action of the LD side pump module (1-2), the gain medium continuously accumulates the number of reversed particles. At this time, the saturable absorber maintains a high-loss state to suppress laser oscillation. When the stored energy reaches the threshold, the absorber suddenly becomes saturated and transparent, and the number of photons in the resonant cavity increases avalanche, forming a nanosecond-level giant pulse. The passive Q-switching switch (1-3) enables the resonant cavity to output a larger seed light. The fifth polarization beam splitter (1-4) and the aperture (1-5) work together to ensure linear polarization and fundamental mode output. The seed light with high peak power and narrow pulse width is coupled out through the output mirror (1-6).

7. The time-domain dual-pulse delay-tunable high-power nanosecond laser according to claim 1, characterized in that, The beam collimation module (10) includes a second positive lens (10-1) and a second negative lens (10-2) arranged sequentially. The center points of the second positive lens (10-1) and the second negative lens (10-2) are set on the same horizontal line. The second positive lens (10-1) converts the diverging beam output by the second single-lamp single-rod amplification module (9) into a converging beam. The second negative lens (10-2) readjusts the converging beam into a collimated parallel light. The distance between the second positive lens (10-1) and the second negative lens (10-2) is the sum of the focal lengths of the positive and negative lenses.

8. The time-domain dual-pulse delay-tunable high-power nanosecond laser according to claim 1 or 7, characterized in that, The delay optical path control module (12) includes a third polarization beam splitter (12-1), a fourth polarization beam splitter (12-2), and a reflection component. The center points of the half-wave plate (11), the third polarization beam splitter (12-1), and the fourth polarization beam splitter (12-2) are set on the same horizontal line. The reflection component is set on the delay optical path between the third polarization beam splitter (12-1) and the fourth polarization beam splitter (12-2).

9. The time-domain dual-pulse delay-tunable high-power nanosecond laser according to claim 8, characterized in that, The reflecting assembly includes a first 45° total reflection mirror (12-3) and a second 45° total reflection mirror (12-4). The first 45° total reflection mirror (12-3) is disposed on the reflected light path of the third polarizing beam splitter (12-1). The center points of the first 45° total reflection mirror (12-3) and the second 45° total reflection mirror (12-4) are disposed on the same horizontal line. The fourth polarizing beam splitter (12-2) is disposed on the reflected light path of the second 45° total reflection mirror (12-4).

10. The time-domain dual-pulse delay-tunable high-power nanosecond laser according to claim 9, characterized in that, The third polarization beam splitter (12-1) and the first 45° total reflection mirror (12-3) are both mounted on the first electric displacement platform. The first 45° total reflection mirror (12-3) is mounted on the slider of the first electric displacement platform. The fourth polarization beam splitter (12-2) and the second 45° total reflection mirror (12-4) are both mounted on the first electric displacement platform. The second 45° total reflection mirror (12-4) is mounted on the slider of the second electric displacement platform.

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