Dual-pulse generation device and method

Abstract

This disclosure provides a dual-pulse generation device and method, relating to the field of solid-state laser technology. The device includes: a laser source suitable for generating linearly polarized short-pulse lasers; a beam splitting module including a polarization beam splitter prism, which is suitable for splitting the linearly polarized short-pulse laser into a first polarized light and a second polarized light whose polarization direction and propagation direction are perpendicular; a pump module suitable for generating pump light; a gain-Q-switching unit suitable for sequentially receiving pump light and the first polarized light, wherein the pump light generates an oscillating laser in the gain-Q-switching unit, and during the injection of the first polarized light into the gain-Q-switching unit, the oscillating laser generates a passively Q-switched pulse laser synchronized with the timing of the first polarized light under the action of the first polarized light, and the passively Q-switched pulse laser is output as the first pulse laser through the polarization beam splitter prism; and an optical path delayer suitable for delaying the second polarized light for a predetermined duration, wherein the delayed second polarized light is output as the second pulse laser through the beam splitting module.

Description

Technical Field

[0001] At least one embodiment of this disclosure relates to the field of solid-state laser technology, and more specifically to a dual-pulse generation device and method. Background Technology

[0002] Dual-pulse laser technology improves measurement and processing accuracy by generating two laser pulses with a defined time interval. Compared to traditional single-pulse lasers, dual-pulse lasers exhibit significant advantages in multiple fields. In laser-induced breakdown spectroscopy, the first laser pulse generates plasma, and the second pulse further excites the plasma, thereby enhancing spectral signal intensity, signal-to-noise ratio, and sensitivity. In lidar detection, high-resolution and precise measurement of target distance and velocity can be achieved by controlling the pulse interval and energy. In materials processing, dual-pulse lasers pre-treat materials with the first pulse and perform fine processing with the second pulse, reducing the heat-affected zone and improving processing accuracy and surface quality. Dual-pulse laser technology demonstrates significant advantages in multiple fields and has broad application potential and development prospects in scientific research, industrial manufacturing, and environmental monitoring.

[0003] Dual-pulse laser systems have a pressing need for laser pulses with high temporal stability and narrow pulse widths in their applications. High temporal stability and narrow pulse widths directly affect the system's measurement accuracy, data repeatability, and overall performance. High temporal stability ensures the reliability, accuracy, and consistency of data during measurement and processing, while narrow pulse widths guarantee fine temporal and spatial resolution and a high signal-to-noise ratio in the field of spectroscopy.

[0004] Currently, the main method for generating dual-pulse lasers is to use a pulse synchronization system to control two independent lasers to generate two pulses with a certain time interval. However, the dual-pulse laser system achieved by this method has a complex structure, large size and weight, high cost, and difficulties in beam combining and optical path alignment of the two pulses. If an integrable passively Q-switched laser is used to reduce size, control cost, and pulse width, problems such as large pulse timing jitter and unstable time interval of the dual-pulse laser still exist. Summary of the Invention

[0005] In view of this, the present disclosure provides a dual-pulse generation device and method.

[0006] According to a first aspect of this disclosure, a dual-pulse generating apparatus is provided, comprising: a laser source 5, adapted to generate linearly polarized short-pulse laser; a beam splitting module, including a polarization beam splitter 7, adapted to split the linearly polarized short-pulse laser into a first polarized light and a second polarized light whose polarization direction and propagation direction are perpendicular; a pumping module, adapted to generate pump light; a gain-Q-switching unit 3, adapted to sequentially receive the pump light and the first polarized light, wherein the pump light generates an oscillating laser in the gain-Q-switching unit, and the oscillating laser generates a passively Q-switched pulse laser synchronized with the timing of the first polarized light under the action of the first polarized light during the injection of the first polarized light into the gain-Q-switching unit, wherein the passively Q-switched pulse laser outputs a first pulse laser through the polarization beam splitter prism; and an optical path delayer 9, adapted to delay the second polarized light for a predetermined duration, wherein the delayed second polarized light outputs a second pulse laser through the beam splitting module, wherein the second pulse laser has a time interval relative to the first pulse laser.

[0007] According to embodiments of this disclosure, the aforementioned gain-Q-switching unit includes a gain medium 31, comprising Nd-doped dielectric material. 3+ A laser crystal for absorbing the pump light and generating the oscillating laser; and a saturable absorber 32 comprising Cr-doped chromium. 4+ The Q-switched crystal is used to adjust the oscillation duration of the oscillating laser under the action of the first polarized light, and output the passively Q-switched pulsed laser.

[0008] Preferably, the gain-Q-switching unit further includes a front endoscope assembly installed between the pump module and the gain medium, and / or a rear endoscope assembly installed between the beam splitter and the saturable absorber.

[0009] According to an embodiment of this disclosure, the gain medium and the saturable absorber are bonded by thermal diffusion; the end face of the gain medium near the pump module is coated with a first pump light antireflection film and a first oscillating laser high reflectivity film, and the end face of the saturable absorber opposite to the gain medium is coated with a second pump light antireflection film and a first oscillating laser partial transmission film.

[0010] Preferably, the end face of the gain medium near the pump module is coated with a first oscillating laser antireflection film, and the front cavity mirror assembly includes: a first plane mirror; a third pump light antireflection film disposed on the side of the first plane mirror near the pump module; a fourth pump light antireflection film disposed on the other side of the first plane mirror; and a second oscillating laser high reflectivity film disposed on the fourth pump light antireflection film; and / or the end face of the saturable absorber opposite to the gain medium is coated with a second oscillating laser antireflection film, and the rear cavity mirror assembly includes: a second plane mirror; a third oscillating laser antireflection film disposed on the side of the second plane mirror near the beam splitter; a fifth pump light antireflection film disposed on the other side of the second plane mirror; and a second oscillating laser partial transmission film disposed on the fifth pump light antireflection film.

[0011] According to an embodiment of this disclosure, the gain medium and the saturable absorber are independently coaxially arranged; the end face of the gain medium near the pump module is coated with a sixth pump light antireflection film and a third oscillating laser high reflectivity film, the other end of the gain medium is coated with a fourth oscillating laser antireflection film, the end face of the saturable absorber opposite to the gain medium is coated with a seventh pump light antireflection film and a third oscillating laser partial transmission film, and the other end of the saturable absorber is coated with a fifth oscillating laser antireflection film.

[0012] Preferably, the end face of the gain medium near the pump module is coated with a sixth oscillating laser antireflection film, and the front cavity mirror assembly includes: a third plane mirror; an eighth pump light antireflection film disposed on the side of the third plane mirror near the pump module; a ninth pump light antireflection film disposed on the other side of the third plane mirror; and a fourth oscillating laser high reflectivity film disposed on the ninth pump light antireflection film; and / or the end face of the saturable absorber opposite to the gain medium is coated with a seventh oscillating laser antireflection film, and the rear cavity mirror assembly includes: a fourth plane mirror; an eighth oscillating laser antireflection film disposed on the side of the fourth plane mirror near the beam splitter; a tenth pump light antireflection film disposed on the other side of the fourth plane mirror; and a fourth oscillating laser partial transmission film disposed on the tenth pump light antireflection film.

[0013] According to embodiments of this disclosure, the pump light is suitable for pumping the gain medium, causing the activated particles in the gain medium to absorb the pump light and achieve population inversion; the first polarized light is suitable for providing bleaching photons to the saturable absorber, causing the saturable absorber to be bleached within a set time.

[0014] According to an embodiment of this disclosure, the pump module includes: a semiconductor pump source 1, suitable for generating pump laser; the wavelength range of the pump laser includes 800~810nm and 880~890nm; and a coupling lens system 2, coupled to the semiconductor pump source through an energy transmission fiber, suitable for focusing the pump laser to obtain the pump light, with a focal length magnification range of 1:0.5~1:4.

[0015] According to embodiments of this disclosure, the beam splitting module further includes a first half-wave plate 6 disposed between the laser source and the polarizing beam splitter prism, adapted to change the polarization direction of the linearly polarized short-pulse laser by rotation, so as to adjust the pulse energy ratio of the first polarized light and the second polarized light; the beam splitting module further includes a second half-wave plate 4 disposed between the gain Q-switching unit and the polarizing beam splitter prism, adapted to change the polarization direction of the first polarized light output from the polarizing beam splitter prism, and also adapted to adjust the polarization direction of the passively Q-switched pulse laser incident on the polarizing beam splitter prism to horizontal polarization.

[0016] According to an embodiment of this disclosure, the beam splitting module further includes a λ / 4 waveplate 8 disposed between the optical path delayer and the polarizing beam splitter, which is adapted to convert the second polarized light output from the polarizing beam splitter into circularly polarized light; the optical path delayer is also adapted to change the optical path of the circularly polarized light by adjusting the structure of the internal delayed optical path, and the circularly polarized light with the changed optical path is converted into a vertically polarized short pulse laser by the λ / 4 waveplate, and the second pulse laser is output by the polarizing beam splitter.

[0017] According to an embodiment of this disclosure, the optical path delayer includes a number of silver-coated mirrors with adjustable spacing, used to control the time interval between the first pulse laser and the second pulse laser.

[0018] According to another aspect of this disclosure, a dual-pulse generation method is provided, comprising: generating a linearly polarized short-pulse laser from a laser source; splitting the linearly polarized short-pulse laser into a first polarized light and a second polarized light using a polarization beam splitter in a beam splitter module; generating pump light using a pump module; receiving the first polarized light and the pump light using a gain-Q-switching unit to obtain a passively Q-switched pulse laser; receiving the passively Q-switched pulse laser using the beam splitter module and outputting a first pulse laser; delaying the second polarized light for a predetermined time using an optical path delayer to obtain a delayed second polarized light; and receiving the delayed second polarized light using the beam splitter module and outputting a second pulse laser.

[0019] According to the dual-pulse generation apparatus and method of this disclosure, a linearly polarized nanosecond pulse laser generated by a laser source is split into a first polarized light and a second polarized light by a polarization beam splitter. The first polarized light is injected into a gain-Q-switching unit, synchronizing the passively Q-switched pulse laser output by the unit with the first polarized light in timing, thus reducing timing jitter. The first pulse laser is then output via a beam splitter. The second polarized light is then introduced into an optical delay unit, allowing for an adjustable predetermined delay before being output via the beam splitter. Therefore, the dual-pulse generated by the dual-pulse generation apparatus of this disclosure features low timing jitter, timing synchronization, and adjustable time intervals. Attached Figure Description

[0020] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 A schematic diagram illustrating the principle of a dual-pulse generating apparatus according to an embodiment of the present disclosure is shown.

[0022] Figure 2 A schematic diagram illustrates a pulse sequence of linearly polarized nanosecond pulsed laser measured by an oscilloscope according to an embodiment of the present disclosure;

[0023] Figure 3 A schematic diagram illustrating the relationship between the output energy of a laser source and the internal pump energy according to an embodiment of the present disclosure is shown.

[0024] Figure 4(a) schematically illustrates a gain-Q-switching unit according to an embodiment of the present disclosure;

[0025] Figure 4(b) schematically illustrates a gain-Q-switching unit according to another embodiment of the present disclosure;

[0026] Figure 4(c) schematically illustrates a gain-Q-switching unit according to another embodiment of the present disclosure;

[0027] Figure 5 This diagram schematically illustrates the pulse sequence changes of a passively Q-switched pulsed laser before and after the first polarized light is injected into a saturable absorber according to an embodiment of the present disclosure.

[0028] Figure 6 A schematic diagram illustrating the relationship between the output power and the injection time difference of a passively Q-switched pulsed laser according to an embodiment of the present disclosure is shown.

[0029] Figure 7 The diagram illustrates the time interval between the first pulsed laser and the second pulsed laser according to an embodiment of the present disclosure as a function of the energy of the first polarized light.

[0030] Figure 8 A flowchart illustrating a dual-pulse generation method according to an embodiment of the present disclosure is shown schematically; and

[0031] Figure 9 The diagram schematically illustrates the pulse time-domain waveforms of a first pulsed laser and a second pulsed laser according to embodiments of the present disclosure. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0034] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0035] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0036] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.

[0037] Laser generation requires a pump source, a gain medium, and a resonant cavity. The pump source provides energy to the laser, exciting the laser working medium and pumping activated particles from the lower laser energy level to the upper laser energy level. The gain medium achieves population inversion and generates stimulated emission of light. The resonant cavity is a space in which light waves are reflected back and forth, providing light energy feedback. The function of the resonant cavity is to select light of a specific frequency and consistent direction, preferentially amplifying it by activating the gain medium, thus forming a laser beam. The Q value is an indicator of the quality of the optical resonant cavity in a laser—the "quality factor."

[0038] Q-switching is a technique that dynamically and in real-time adjusts the quality factor (Q value) of an optical resonator, transforming continuous laser output into intermittent pulsed output. Also known as Q-switching, it compresses the energy of a normally continuous laser output into extremely narrow pulses, thereby increasing the peak power of the light source by several orders of magnitude. Active Q-switching is achieved by actively introducing or adding a modulator to the laser resonator. Passive Q-switching utilizes the saturation absorption effect of nonlinear optical materials to achieve rapid Q-switching. Passive Q-switching is easier to design and use, generally does not require an external power supply, and is more stable and reliable.

[0039] Passive Q-switching technology utilizes the inherent characteristics of saturable absorbers, namely, their absorption coefficient is not constant. Under strong laser light, the absorption coefficient decreases with increasing light intensity until saturation, resulting in transparency. The specific physical process of a passively Q-switched laser is as follows: Initially, the fluorescence generated by the gain medium within the resonant cavity is weak, the absorption coefficient of the saturable absorber is large, and the light transmittance is very low. The resonant cavity is in a low Q-value (high loss) state and cannot form laser oscillation. As the pump light continues to act, the accumulation of the inverted particle number in the gain medium gradually strengthens the fluorescence within the resonant cavity, the absorption coefficient decreases, and the transmittance gradually increases. When the saturable absorber reaches saturation, i.e., the absorption coefficient is at its minimum, the saturable absorber is suddenly "bleached" and becomes transparent. The Q-value within the resonant cavity surges, generating laser oscillation and outputting a passively Q-switched laser pulse.

[0040] This disclosure presents a low-timing jitter dual-pulse generation device based on the principle of passively Q-switched lasers and seed injection.

[0041] Current methods for generating dual-pulse lasers also include:

[0042] 1. A laser beam splitter splits the laser pulse output from a single laser into two independent beams. Then, an optical delay line (such as a tunable mirror or fiber delay line) is used to introduce a time delay into one of the laser beams, thus forming a double-pulse laser with a certain time interval. Although this method is simple in structure and low in cost, the beam splitter structure will reduce the energy of both laser pulses. The single laser setting reduces the flexibility of the double-pulse laser system. When the single laser is a passively Q-switched laser with a compressible pulse width, the timing stability between the two pulses is poor.

[0043] 2. Using Q-switching technology to modulate the loss in the cavity of an actively Q-switched laser to generate two pulsed lasers with controllable time intervals, this method requires a precise external circuit control system and optical alignment. Repeatedly opening and closing the Q-switch will cause serious thermal effects and energy loss, resulting in reduced output power and energy efficiency. Moreover, this method is not suitable for passively Q-switched lasers with large pulse timing jitter.

[0044] In general, existing technologies suffer from at least the following drawbacks and shortcomings: Most dual-pulse laser generation schemes employ actively modulated pulsed lasers, resulting in complex system structures, large size and weight, high cost, and difficulties in beam combining and optical path alignment. The longer cavity length typically leads to increased pulse width and reduced peak power. Passively Q-switched lasers, which offer compressible size, lower control costs, and narrower pulse widths, cannot be commonly used for dual-pulse laser generation due to issues such as large pulse timing jitter and unstable dual-pulse laser time intervals. This reduces the overall performance and application applicability of existing dual-pulse laser systems.

[0045] Embodiments of this disclosure provide a dual-pulse generation device, comprising: a laser source suitable for generating linearly polarized short-pulse laser; a beam splitting module including a polarization beam splitter prism, the polarization beam splitter prism being suitable for splitting the linearly polarized short-pulse laser into a first polarized light and a second polarized light whose polarization direction and propagation direction are perpendicular; a pump module suitable for generating pump light; a gain-Q-switching unit suitable for sequentially receiving pump light and the first polarized light, the pump light generating oscillating laser in the gain-Q-switching unit, the oscillating laser generating a passively Q-switched pulse laser synchronized with the first polarized light under the action of the first polarized light during the injection of the first polarized light into the gain-Q-switching unit, the passively Q-switched pulse laser being output as the first pulse laser through the polarization beam splitter prism; and an optical path delayer suitable for delaying the second polarized light for a predetermined duration, the delayed second polarized light being output as the second pulse laser through the beam splitting module, wherein the second pulse laser has a time interval relative to the first pulse laser.

[0046] Figure 1 A schematic diagram of a dual-pulse generating apparatus according to an embodiment of the present disclosure is shown.

[0047] like Figure 1 As shown, the dual-pulse generating device includes a laser source 5, a beam splitting module, a pumping module, a gain-Q-switching unit 3, and an optical path delayer 9. The beam splitting module includes a polarization beam splitter 7.

[0048] According to embodiments of this disclosure, laser source 5 is used to generate linearly polarized short-pulse lasers including a 1μm wavelength band.

[0049] According to embodiments of this disclosure, the laser source 5 can be an actively Q-switched laser, an actively mode-locked laser, a semiconductor laser, or a fiber laser.

[0050] According to embodiments of this disclosure, laser source 5 can generate linearly polarized short-pulse lasers with adjustable output power. The linearly polarized short-pulse laser can be a linearly polarized femtosecond pulse laser, a linearly polarized picosecond pulse laser, a linearly polarized sub-nanosecond pulse laser, or a linearly polarized nanosecond pulse laser.

[0051] According to embodiments of this disclosure, the laser source 5 can also be an electro-optic Q-switched nanosecond pulse laser that outputs a 1064nm linearly polarized nanosecond pulse laser with a repetition frequency of 1kHz.

[0052] Figure 2 A schematic diagram of a pulse sequence of linearly polarized nanosecond pulsed laser measured by an oscilloscope according to an embodiment of the present disclosure is shown.

[0053] like Figure 2 As shown, the pulse sequence displayed on the oscilloscope includes at least 1000 linearly polarized nanosecond laser pulses. The oscilloscope can measure the distribution of the pulse sequence, and the histogram function of the oscilloscope can calculate the standard deviation of the pulse sequence. The timing jitter of the linearly polarized nanosecond laser pulse is 708 ps, indicating that the electro-optic Q-switched nanosecond laser can output linearly polarized nanosecond laser pulses with low timing jitter.

[0054] According to embodiments of this disclosure, the linearly polarized short-pulse laser output from the laser source has extremely high peak power and an extremely steep rise edge waveform.

[0055] Figure 3 A schematic diagram illustrating the relationship between the output energy of a laser source and the internal pump energy according to an embodiment of the present disclosure is shown.

[0056] like Figure 3 As shown, with the increase of the pump energy of the internal pump source of the laser source, the output energy of the laser source gradually increases, with the highest output energy value being 2.683 mJ.

[0057] According to embodiments of this disclosure, the beam splitting module includes a polarizing beam splitter 7, which is adapted to split linearly polarized short-pulse laser light from the laser source into a first polarized light whose polarization direction and propagation direction are both perpendicular (e.g., Figure 1 The beam propagating along the negative x-axis from the polarizing beam splitter 7 and the second polarized light (e.g., the beam transmitted along the negative x-axis from the polarizing beam splitter 7). Figure 1 The beam output from the medium polarization beam splitter 7 propagates along the positive y-axis.

[0058] According to embodiments of this disclosure, the output energy of the laser source 5 is adjustable, that is, the output energy of the first polarized light and the second polarized light is adjustable, and the output energy of the final second pulsed laser is also adjustable.

[0059] According to embodiments of this disclosure, the linearly polarized short-pulse laser generated by laser source 5 has the characteristic of low timing jitter.

[0060] According to embodiments of this disclosure, the surface of the polarizing beam splitter 7 may be coated with a 1064nm band antireflection film.

[0061] According to embodiments of this disclosure, the first polarized light is vertically polarized light, and the second polarized light is horizontally polarized light.

[0062] According to embodiments of this disclosure, a pump module is adapted to generate pump light; a gain-Q-switching unit 3 is adapted to sequentially receive pump light and first polarized light. The pump light generates oscillating laser light in the gain-Q-switching unit 3. During the period when the first polarized light is injected into the gain-Q-switching unit 3, the oscillating laser light generates a passively Q-switched pulsed laser synchronized with the timing of the first polarized light. The passively Q-switched pulsed laser is output as a first pulsed laser light via a polarization beam splitter prism 7. An optical path delayer 9 is adapted to delay the second polarized light for a predetermined duration. The delayed second polarized light is output as a second pulsed laser light via a beam splitter module. The second pulsed laser light has a time interval relative to the first pulsed laser light.

[0063] In detail, according to the embodiments of this disclosure, a linearly polarized nanosecond pulse laser with low timing jitter and adjustable energy is generated by a laser source 5. This linearly polarized nanosecond pulse laser is split into a first polarized beam and a second polarized beam by a polarization beam splitter 7. The first polarized beam is injected into a gain-Q-switching unit 3, synchronizing the passively Q-switched pulse laser output from the gain-Q-switching unit 3 with the first polarized beam in timing, thus reducing timing jitter. The first pulse laser is then output by the beam splitter module. The second polarized beam is then delayed for an adjustable predetermined time by entering an optical delay unit 9, before being output by the beam splitter module. Therefore, the dual-pulse generation device of this disclosure generates dual pulses with low timing jitter and adjustable energy, as well as timing synchronization and adjustable time intervals. Furthermore, the dual-pulse generation device of this disclosure reduces the size of the dual-pulse laser system, lowers system costs, and can meet the miniaturization and integration requirements of dual-pulse laser systems in various application scenarios.

[0064] Figure 4(a) schematically illustrates a gain-Q-switching unit according to an embodiment of the present disclosure.

[0065] According to embodiments of this disclosure, such as Figure 1 As shown in Figure 4(a), the gain-Q-switching unit includes a gain medium 31 and a saturable absorber 32.

[0066] According to embodiments of this disclosure, the gain medium 31 includes Nd-doped material. 3+ A laser crystal used to absorb pump light and generate oscillating laser light.

[0067] For example, the gain medium 31 is an Nd:YAG crystal with dimensions of 5mm × 3mm × 3mm, along... <111> It is oriented and cut, Nd 3+ The doping concentration is 1.1 at.%.

[0068] According to embodiments of this disclosure, the saturable absorber 32 includes Cr doped components. 4+ The Q-switched crystal is used to adjust the oscillation duration of the oscillating laser under the action of the first polarized light, and to adjust the loss of the resonant cavity under the action of the oscillating laser, so as to output a passively Q-switched pulsed laser.

[0069] For example, the saturable absorber 32 is a Cr:YAG crystal with dimensions of 2mm × 3mm × 3mm, along... <100> It is oriented and cut, with an initial transmittance of 50%.

[0070] According to embodiments of this disclosure, the gain-Q-switching unit 3 may further include a front endoscope assembly mounted between the pump module and the gain medium 31.

[0071] According to embodiments of this disclosure, the gain-Q-switching unit 3 may further include a rear cavity mirror assembly mounted between the beam splitter module and the saturable absorber 32.

[0072] According to an embodiment of this disclosure, the two end faces of the gain-Q-tuning unit 3 are coated to form a resonant cavity.

[0073] According to an embodiment of this disclosure, as shown in FIG4(a), the gain medium 31 and the saturable absorber 32 are joined together by thermal diffusion bonding. Thermal diffusion bonding, also known as thermal bonding, involves bonding two precision-machined crystals together after a series of surface treatments, followed by heat treatment of the crystals to form a permanent bond.

[0074] As shown in Figure 4(a), the end face of the gain medium 31 near the pump module (the left end face in Figure 4(a)) is coated with a first pump light antireflection film 311 that allows pump light from the pump light module to pass through and a first oscillating laser high reflectivity film 312 that reflects the oscillating light in the gain-Q-switching unit. The end face of the saturable absorber 32 opposite to the gain medium 31 (the right end face in Figure 4(a)) is coated with a second pump light antireflection film 321 that allows pump light from the gain-Q-switching unit to pass through and a first oscillating laser partial transmission film 322 that allows the oscillating light from the gain-Q-switching unit to partially pass through.

[0075] According to embodiments of this disclosure, the gain medium 31 and the saturable absorber 32 can be integrated by thermal bonding technology to form a gain Q-switching unit 3. After coating at both ends, a resonant cavity with a length of less than 10 mm can be formed to output sub-nanosecond passively Q-switched pulse laser.

[0076] According to embodiments of the present disclosure, a first pump light antireflection film 311 allows pump light to pass through, a first oscillating laser high reflectivity film 312 is used for high reflectivity of the oscillating laser, and a first oscillating laser partial transmission film 322 allows partial transmission of the oscillating laser, with the transmission ratio including 10% to 90%, for example: a transmission ratio of 10%, a transmission ratio of 50%, and a transmission ratio of 90%.

[0077] For example, the first pump light antireflection film 311 is an 808nm antireflection film, the first oscillating laser high reflectivity film 312 is a 1064nm high reflectivity film, and the first oscillating laser partial transmission film 322 is a partial transmission film with a 1064nm transmittance and a 50% transmittance ratio.

[0078] Figure 4(b) schematically illustrates a gain-Q-switching unit according to another embodiment of the present disclosure. The gain-Q-switching unit shown in Figure 4(b) is an improvement on the gain-Q-switching unit shown in Figure 4(a), the difference being the addition of a front endoscope assembly and a rear endoscope assembly.

[0079] In another embodiment of this disclosure, as shown in FIG4(b), the end face of the gain medium 31 near the pump module is coated with a first oscillating laser antireflection film 313, and the front cavity mirror assembly includes: a first plane mirror 33; a third pump light antireflection film 314 disposed on the side of the first plane mirror near the pump module; a fourth pump light antireflection film 315 disposed on the other side of the first plane mirror; and a second oscillating laser high reflectivity film 316 disposed on the fourth pump light antireflection film 315; and the end face of the saturable absorber opposite to the gain medium is coated with a second oscillating laser antireflection film 323, and the rear cavity mirror assembly includes: a second plane mirror 34; a third oscillating laser antireflection film 324 disposed on the side of the second plane mirror near the beam splitter; a fifth pump light antireflection film 325 disposed on the other side of the second plane mirror; and a second oscillating laser partial transmission film 326 disposed on the fifth pump light antireflection film 325.

[0080] According to an embodiment of this disclosure, the end face of the gain medium near the pump module is coated with a first oscillating laser antireflection film 313 and a front cavity mirror assembly.

[0081] According to embodiments of this disclosure, the end face of the saturable absorber opposite to the gain medium is coated with a second oscillating laser antireflection film 323, and a rear cavity mirror assembly.

[0082] According to embodiments of this disclosure, the resonant cavity can be formed by two crystal end faces after coating, or by two plane mirrors after coating, or by one end face of the coated crystal and a plane mirror at the other end.

[0083] Figure 4(c) schematically illustrates a gain-Q-switching unit according to another embodiment of the present disclosure.

[0084] As shown in Figure 4(c), the end face of the gain medium 31 near the pump module is coated with a sixth pump light antireflection film 317 and a third oscillating laser high reflectivity film 318. The other end of the gain medium 31 is coated with a fourth oscillating laser antireflection film 319. The end face of the saturable absorber 32 opposite to the gain medium 31 is coated with a seventh pump light antireflection film 327 and a third oscillating laser partial transmission film 328. The other end of the saturable absorber 32 is coated with a fifth oscillating laser antireflection film 329.

[0085] According to embodiments of this disclosure, a sixth oscillating laser antireflection film is deposited on the end face of the gain medium near the pump module, and the front cavity mirror assembly includes: a third plane mirror; an eighth pump light antireflection film disposed on the side of the third plane mirror near the pump module; a ninth pump light antireflection film disposed on the other side of the third plane mirror; and a fourth oscillating laser high reflectivity film disposed on the ninth pump light antireflection film; and a seventh oscillating laser antireflection film is deposited on the end face of the saturable absorber opposite to the gain medium, and the rear cavity mirror assembly includes: a fourth plane mirror; an eighth oscillating laser antireflection film disposed on the side of the fourth plane mirror near the beam splitter; a tenth pump light antireflection film disposed on the other side of the fourth plane mirror; and a fourth oscillating laser partial transmission film disposed on the tenth pump light antireflection film.

[0086] According to an embodiment of this disclosure, the end face of the gain medium near the pump module is coated with a sixth oscillating laser antireflection film and a front cavity mirror assembly.

[0087] According to embodiments of this disclosure, the end face of the saturable absorber opposite to the gain medium is coated with a seventh oscillating laser antireflection film, and a rear cavity mirror assembly.

[0088] According to embodiments of this disclosure, the gain medium and the saturable absorber are arranged coaxially, and plane mirrors are placed at both ends. After coating, a resonant cavity is formed. This resonant cavity has a relatively long length, generally greater than or equal to 10 mm, and can output nanosecond passively Q-switched pulse laser.

[0089] According to embodiments of this disclosure, the pump light is suitable for pumping a gain medium, such that the active particles in the gain medium absorb the pump light to achieve population inversion.

[0090] According to embodiments of this disclosure, the gain medium absorbs the pump light, and the activated particles within the Nd:YAG crystal of the gain medium transition from the ground state to the excited state, storing the pump light energy in the upper energy level of the laser. When the Cr:YAG Q-switched crystal of the saturable absorber is not bleached, i.e., the resonant cavity is in the closed state, the number of particles in the upper energy level continuously accumulates and generates a large number of inverted particles. When the Cr:YAG crystal is bleached, i.e., the Q-switching switch of the resonant cavity is turned on, the gain in the resonant cavity exceeds the loss, satisfying the laser oscillation condition, and a rapid and intense stimulated emission amplification is achieved through the feedback of the resonant cavity, establishing laser oscillation within the resonant cavity, and finally outputting laser light. The duration from bleaching the saturable absorber to turning on the switch in this case is called the first duration, including 50μs-200μs, for example: 50μs, 100μs, 200μs. The passively Q-switched pulsed laser obtained in this case has a large timing jitter, for the following reasons:

[0091] During photon number accumulation within the resonant cavity, it is susceptible to various random perturbations, such as variations in pump light intensity, changes in the pump spatial mode distribution within the resonant cavity, alterations in the spectral characteristics of the gain medium, thermal effects of the gain medium, and spontaneous emission noise. These random perturbations interact to influence the threshold condition of the passively Q-switched laser. Different threshold conditions result in the output of each passively Q-switched laser pulse occurring at a slightly different time relative to the start time of the pump light pulse, leading to pulse timing jitter in the normally output passively Q-switched laser pulse that is several orders of magnitude longer than the pulse duration.

[0092] According to embodiments of this disclosure, the first polarized light is adapted to provide bleaching photons to a saturable absorber, such that the saturable absorber is bleached within a set time.

[0093] According to embodiments of this disclosure, the first polarization source is a linearly polarized short-pulse laser output from a laser source, possessing extremely high peak power and a very jittery rising edge waveform. Injecting this first polarized light into a saturable absorber, the Cr:YAG crystal, instantly provides a large number of bleaching photons to the saturable absorber, causing the Cr:YAG crystal to be bleached within a set time. During the entire passively Q-switched pulse laser output time, the oscillating passively Q-switched pulse laser is output ahead of the first polarized light injection time, thereby reducing the timing jitter of the passively Q-switched pulse laser and achieving timing synchronization with the first polarized light. The duration during which the saturable absorber is bleached ahead of the time the switch is turned on in this case is called the second duration.

[0094] According to embodiments of this disclosure, the second duration is the set time, which is less than the first duration. The time difference between the first duration and the second duration is called the injection time difference. The duration of the injection time difference includes 2-110μs, for example: 2μs, 50μs, 110μs.

[0095] For example, the injection of the first polarized light causes the saturable absorber to be bleached in advance, so that the passively Q-switched pulsed laser is output in the first 110 μs of normal output.

[0096] According to embodiments of this disclosure, the bleaching process after the first polarized light is injected into the saturable absorber has a certain duration. Therefore, there is a certain time interval between the passively Q-switched pulsed laser and the first polarized light. The time interval includes 5ns-20ns, for example: 5ns, 10ns, 20ns.

[0097] Figure 5 The diagram schematically illustrates the pulse sequence changes of a passively Q-switched pulsed laser before and after the first polarized light is injected into a saturable absorber according to an embodiment of the present disclosure.

[0098] like Figure 5As shown, the pulse sequence before injection represents the 1000 pulses of the passively Q-switched laser output when the first polarized light is not injected into the saturable absorber. This pulse sequence is distributed over a certain time scale, and the time-domain waveforms of all pulses cannot be observed simultaneously in the oscilloscope display window. The pulse sequence after injection represents the 1000 pulses of the passively Q-switched laser output when the first polarized light is injected into the saturable absorber. This pulse sequence is distributed only over a smaller time scale, and the pulse waveforms are visible. Injecting the first polarized light into the saturable absorber reduces the pulse timing jitter of the passively Q-switched laser from 561.2 ns to 344 ps.

[0099] Figure 6 The diagram illustrates the relationship between the output power and the injection time difference of a passively Q-switched pulsed laser according to an embodiment of the present disclosure.

[0100] like Figure 6 As shown, the output power of the passively Q-switched pulsed laser gradually increases as the injection time difference decreases, indicating that the output power of the passively Q-switched pulsed laser can be adjusted by changing the injection time difference and adjusting the injection time of the first polarized light.

[0101] According to embodiments of this disclosure, a portion of a linearly polarized short-pulse laser generated by a laser source, such as first polarized light, is injected into a gain-Q-switching unit to assist in bleaching a saturable absorber. This achieves timing synchronization locking between the passively Q-switched pulse laser and the first polarized light, reducing the timing jitter of the passively Q-switched pulse laser to the picosecond level. Simultaneously, it optimizes the stability of the time-domain waveform and output power of the passively Q-switched pulse laser, resulting in a higher-quality dual-pulse.

[0102] According to embodiments of this disclosure, the pump module includes a semiconductor pump source 1 and a coupling lens system 2.

[0103] According to embodiments of this disclosure, the semiconductor pump source can be an optical fiber coupled output semiconductor laser, suitable for generating pump lasers; the wavelength range of the pump laser includes 800~810nm and 880~890nm, and the wavelength of the pump laser can be adjusted by changing the operating temperature of the pump source inside the semiconductor pump source.

[0104] For example, at room temperature, the center wavelength of the pump laser is 806 nm.

[0105] According to embodiments of this disclosure, the coupling lens system can be an optical fiber output focusing lens, coupled to a semiconductor pump source via an energy transmission optical fiber, suitable for focusing pump laser to obtain pump light. The focal length magnification range includes 1:0.5 to 1:4, for example: focal length magnification of 1:0.5, focal length magnification of 1:0.8, focal length magnification of 1:1, focal length magnification of 1:4, and the focal length magnification can be continuously adjusted.

[0106] According to embodiments of this disclosure, the core diameter of the power transmission optical fiber can be 400 μm, and the numerical aperture can be 0.22.

[0107] For example, when a pump laser is transmitted through a power fiber, a coupling lens system focuses the pump laser into a pump light. When the focal length ratio is 1:1, the diameter of the pump light spot is 400 μm. The light is incident on the gain medium of the Q-switching unit, and the focal point is located 1 mm from the inner surface of the gain medium.

[0108] According to embodiments of this disclosure, the beam splitting module further includes a first half-wave plate 6 disposed between the laser source and the polarizing beam splitter prism, which is suitable for changing the polarization direction of the linearly polarized short-pulse laser by rotation, so as to adjust the pulse energy ratio of the first polarized light and the second polarized light.

[0109] For example, an electro-optic Q-switched nanosecond pulsed laser generates a 2.682 mJ 1064 nm linearly polarized nanosecond pulsed laser. Rotating the first half-wave plate adjusts the pulse energy of the first polarized light and the second polarized light to 0.382 mJ and 2.3 mJ, respectively.

[0110] According to embodiments of this disclosure, the first half-wave plate may be coated with a 1064nm band antireflection film.

[0111] Figure 7 The diagram illustrates a graph showing the time interval between the first pulsed laser and the second pulsed laser according to an embodiment of the present disclosure as a function of the energy of the first polarized light.

[0112] like Figure 7 As shown, the horizontal axis represents the seed light energy, indicating the energy of the first polarized light injected into the saturable absorber, while the vertical axis represents the pulse time interval, indicating the time interval between the first and second laser pulses. As the energy of the first polarized light increases, the time interval between the first and second laser pulses gradually decreases, with a minimum interval of 9.5 ns.

[0113] According to embodiments of this disclosure, after setting the output energy of the laser source, the ratio of pulse energy can be adjusted by using a first half-wave plate to regulate the energy of the first polarized light injected into the saturable absorber, thereby adjusting the time interval between the first pulse laser and the second pulse laser within a small range.

[0114] According to embodiments of this disclosure, the beam splitting module further includes a second half-wave plate 4 disposed between the gain Q-switching unit and the polarization beam splitter prism. This plate is suitable for changing the polarization direction of the first polarized light output from the polarization beam splitter prism and for adjusting the polarization direction of the passively Q-switched pulsed laser incident on the polarization beam splitter prism to horizontal polarization, so as to ensure that the passively Q-switched pulsed laser is fully coupled and output through the polarization beam splitter prism.

[0115] According to embodiments of this disclosure, the second half-wave plate may be coated with a 1064nm band antireflection film.

[0116] According to an embodiment of this disclosure, the polarization direction of the passively Q-switched pulsed laser is adjusted to horizontal polarization by a second half-wave plate, and a zero-angle transmission polarization beam splitter is used to form a first pulsed laser.

[0117] According to embodiments of this disclosure, the beam splitting module further includes a λ / 4 waveplate 8 disposed between the optical path delayer and the polarizing beam splitter, which is suitable for converting the second polarized light output from the polarizing beam splitter into circularly polarized light.

[0118] According to embodiments of this disclosure, a λ / 4 waveplate can be coated with a 1064nm band antireflection coating.

[0119] According to embodiments of this disclosure, the optical path delayer is also suitable for changing the optical path of circularly polarized light by adjusting the structure of the internal delayed optical path. The circularly polarized light with the changed optical path is converted into a vertically polarized short pulse laser by a λ / 4 waveplate, and then output as a second pulse laser by a polarizing beam splitter.

[0120] According to embodiments of this disclosure, the optical delay device includes silver-coated mirrors of adjustable number and adjustable spacing for controlling the time interval between a first pulse laser and a second pulse laser.

[0121] According to embodiments of this disclosure, the silver-coated mirror can maintain an average reflectivity of 98.5% for lasers incident at any angle in the 450-2000nm wavelength range, and the substrate material of the silver-coated mirror lens is K9 glass.

[0122] According to embodiments of this disclosure, the optical path of the second polarized light is changed by adjusting the number and spacing of the silver-coated mirrors, thereby controlling the time interval between the first and second pulsed lasers over a wide range.

[0123] Figure 8 A flowchart illustrating a dual-pulse generation method according to an embodiment of the present disclosure is shown schematically.

[0124] like Figure 8 As shown, the dual-pulse generation method includes operations S810 to S870.

[0125] When operating the S810, the laser source generates linearly polarized short-pulse laser.

[0126] When operating the S820, the polarization beam splitter in the beam splitter module splits the linearly polarized short-pulse laser into first polarized light and second polarized light.

[0127] When operating the S830, pump light is generated using the pump module.

[0128] When operating the S840, the gain-Q-switching unit is used to receive the first polarized light and the pump light to obtain a passively Q-switched pulsed laser.

[0129] When operating the S850, the beam splitter module receives passively Q-switched pulsed laser light and outputs the first pulsed laser light.

[0130] When operating the S860, the second polarized light is delayed for a predetermined time using an optical delay device to obtain the delayed second polarized light.

[0131] When operating the S870, the second polarized light with delay is received by the beam splitter module, and the second pulse laser is output.

[0132] Figure 9 The diagram schematically illustrates the pulse time-domain waveforms of a first pulsed laser and a second pulsed laser according to embodiments of the present disclosure.

[0133] like Figure 9 As shown, the first laser pulse is a passively Q-switched laser with a relatively narrow pulse width of 852 ps. The second laser pulse is a nanosecond laser with a relatively wide pulse width of 4.658 ns. The time interval between the first and second laser pulses is 8.8 ns.

[0134] In summary, this invention provides a seed-injection-based dual-pulse generation device and method. Seed injection involves injecting first polarized light into a gain-Q-switching unit to affect passively Q-switched pulsed laser. A linearly polarized short-pulse laser with low timing jitter and tunable energy is generated by a laser source. This laser is then split into first polarized light and second polarized light, both with perpendicular polarization and propagation directions, by a polarization beam splitter in the beam splitter module. The first polarized light is injected into the gain-Q-switching unit to rapidly bleach the saturable absorber, reducing the timing jitter of the passively Q-switched pulsed laser. This first polarized light is synchronized and locked with the timing of the first polarized light, and is then output as the first pulsed laser by the beam splitter module. The second polarized light is delayed for a certain time by an optical delay unit before being output as the second pulsed laser by the beam splitter module.

[0135] The laser source can adjust the energy of the first polarized light. The first half-wave plate can adjust the energy ratio of the first and second polarized light to regulate the time interval between the first and second pulse lasers within a small range. The injection time difference of the first polarized light can adjust the output power of the first pulse laser. The laser source can also adjust the output power of the second pulse laser. The delay function of the optical path delayer can adjust the time interval between the first and second pulse lasers within a large range. Therefore, a dual-pulse laser with a timing-locked relationship, a specific time interval, and adjustable time interval, pulse energy, and output power is formed, resulting in a dual-pulse laser with high timing stability and a narrow pulse width.

[0136] This invention solves the problem that passively Q-switched lasers cannot be used as commonly used lasers in dual-pulse laser generation schemes, compresses the size of dual-pulse laser systems, reduces system costs, and can meet the miniaturization and integration requirements of dual-pulse laser systems in various application scenarios. At the same time, it can generate low-timing jitter dual-narrow-pulse lasers with adjustable pulse time intervals and energy.

[0137] The dual-pulse generation device and method disclosed herein have certain practical applications. While reducing system cost and ensuring high system flexibility, they achieve dual-pulse lasers with high temporal stability and narrow pulse width as much as possible. This ensures the reliability and accuracy of data in measurement and processing using the dual-pulse laser system, improves the detection and measurement accuracy of dual-pulse lasers, and enhances temporal and spatial resolution and signal-to-noise ratio.

[0138] In this embodiment of the invention, the type, doping concentration, or size of the gain medium and saturable absorber can be selected according to actual needs. The coating type, parameters, specifications, radius of curvature, and other parameters of the internal reflector of the optical delay can be selected based on the output characteristics such as the output wavelength and output power of the short-pulse laser. The type, output wavelength, output power, and other output characteristics of the short-pulse laser can be selected based on the bleaching effect and application requirements of the Cr:YAG saturable absorber in the passively Q-switched laser.

[0139] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A dual-pulse generating device, characterized in that, include: Laser source (5), suitable for generating linearly polarized short pulse laser; The beam splitting module includes a polarizing beam splitter (7), which is suitable for splitting the linearly polarized short pulse laser into a first polarized light and a second polarized light whose polarization direction and propagation direction are perpendicular. Pump module, suitable for generating pump light; The gain-Q-switching unit (3) is adapted to receive the pump light and the first polarized light in sequence. The pump light generates an oscillating laser in the gain-Q-switching unit. During the period when the first polarized light is injected into the gain-Q-switching unit, the oscillating laser generates a passively Q-switched pulse laser that is time-synchronized with the first polarized light under the action of the first polarized light. The passively Q-switched pulse laser outputs a first pulse laser through the polarization beam splitter. as well as The optical path delay unit (9) is suitable for delaying the second polarized light for a predetermined time. The delayed second polarized light is output as a second pulse laser by the beam splitting module, wherein the second pulse laser has a time interval relative to the first pulse laser.

2. The dual-pulse generating device according to claim 1, characterized in that, The gain-Q-tuning unit includes: Gain medium (31), including Nd-doped medium 3+ A laser crystal for absorbing the pump light and generating the oscillating laser; and Saturable absorber (32), including Cr doped 4+ A Q-switched crystal is used to adjust the oscillation duration of the oscillating laser under the action of the first polarized light, and output the passively Q-switched pulsed laser. Preferably, the gain-Q-switching unit further includes a front endoscope assembly installed between the pump module and the gain medium, and / or a rear endoscope assembly installed between the beam splitter and the saturable absorber.

3. The dual-pulse generating device according to claim 2, characterized in that, The gain medium and the saturable absorber are bonded by thermal diffusion; The end face of the gain medium near the pump module is coated with a first pump light antireflection film and a first oscillating laser high reflectivity film, and the end face of the saturable absorber opposite to the gain medium is coated with a second pump light antireflection film and a first oscillating laser partial transmission film. Preferably, the end face of the gain medium near the pump module is coated with a first oscillating laser antireflection film, and the front cavity mirror assembly includes: First plane mirror; A third pump light antireflection film is disposed on the side of the first plane mirror near the pump module; A fourth pump-guided anti-reflection coating is disposed on the other side of the first plane mirror; and A second oscillating laser high-reflectivity film is disposed above the fourth pump light antireflection film; and / or The end face of the saturable absorber opposite to the gain medium is coated with a second oscillating laser antireflection film, and the rear cavity mirror assembly includes: Second plane mirror; The third oscillating laser antireflection coating is disposed on the side of the second plane mirror near the beam splitting module; A fifth pump-guided anti-reflection coating is disposed on the other side of the second plane mirror; and The second oscillating laser partial transmission film is disposed on the fifth pump light antireflection film.

4. The dual-pulse generating device according to claim 2, characterized in that, The gain medium and the saturable absorber are independently coaxially arranged; The end face of the gain medium near the pump module is coated with a sixth pump light antireflection film and a third oscillating laser high reflectivity film, the other end of the gain medium is coated with a fourth oscillating laser antireflection film, the end face of the saturable absorber opposite to the gain medium is coated with a seventh pump light antireflection film and a third oscillating laser partial transmission film, and the other end of the saturable absorber is coated with a fifth oscillating laser antireflection film. Preferably, the end face of the gain medium near the pump module is coated with a sixth oscillating laser antireflection film, and the front cavity mirror assembly includes: Third plane mirror; The eighth pump light antireflection film is disposed on the side of the third plane mirror near the pump module; A ninth pump-guided anti-reflection coating is disposed on the other side of the third plane mirror; and A fourth oscillating laser high-reflectivity film is disposed above the ninth pump light antireflection film; and / or The end face of the saturable absorber opposite to the gain medium is coated with a seventh oscillating laser antireflection film, and the rear cavity mirror assembly includes: Fourth plane mirror; The eighth oscillating laser antireflection coating is disposed on the side of the fourth plane mirror near the beam splitting module; The tenth pump light antireflection film is disposed on the other side of the fourth plane mirror; and The fourth oscillating laser partial transmission film is disposed on the tenth pump light antireflection film.

5. The dual-pulse generating device according to claim 2, characterized in that: The pump light is suitable for pumping the gain medium, so that the active particles in the gain medium absorb the pump light to achieve population inversion. The first polarized light is adapted to provide bleaching photons to the saturable absorber, so that the saturable absorber is bleached within a set time.

6. The dual-pulse generating device according to any one of claims 1-4, characterized in that, The pump module includes: A semiconductor pump source (1) is suitable for generating a pump laser; the wavelength range of the pump laser includes 800~810nm and 880~890nm; and The coupling lens system (2) is coupled to the semiconductor pump source through an energy transmission fiber and is suitable for focusing the pump laser to obtain the pump light. The focal length magnification range includes 1:0.5 to 1:

4.

7. The dual-pulse generating device according to any one of claims 1-4, characterized in that: The beam splitting module also includes a first half-wave plate (6) disposed between the laser source and the polarization beam splitter, which is suitable for changing the polarization direction of the linearly polarized short pulse laser by rotation, so as to adjust the pulse energy ratio of the first polarized light and the second polarized light; The beam splitting module further includes a second half-wave plate (4) disposed between the gain Q-switching unit and the polarization beam splitter, which is adapted to change the polarization direction of the first polarized light output from the polarization beam splitter and also adapted to adjust the polarization direction of the passively Q-switched pulse laser incident on the polarization beam splitter to horizontal polarization.

8. The dual-pulse generating device according to any one of claims 1-4, characterized in that, The beam splitting module also includes a λ / 4 waveplate (8) disposed between the optical path delayer and the polarizing beam splitter, which is suitable for converting the second polarized light output from the polarizing beam splitter into circularly polarized light; The optical path delayer is also suitable for changing the optical path of the circularly polarized light by adjusting the structure of the internal delayed optical path. The circularly polarized light with the changed optical path is converted into a vertically polarized short pulse laser by a λ / 4 waveplate, and then output as the second pulse laser by the polarization beam splitter.

9. The dual-pulse generating device according to claim 8, characterized in that: The optical path delayer includes silver-coated mirrors with adjustable number and spacing, used to control the time interval between the first pulse laser and the second pulse laser.

10. A method for generating a dual pulse using the dual pulse generating apparatus as described in any one of claims 1-9, characterized in that, include: The laser source generates linearly polarized short-pulse laser light; The linearly polarized short-pulse laser is split into first polarized light and second polarized light using a polarization beam splitter in the beam splitting module. Pump light is generated using a pump module; By using a gain-Q-switching unit, the first polarized light and the pump light are received to obtain a passively Q-switched pulsed laser. The beam splitter module receives the passively Q-switched pulsed laser and outputs a first pulsed laser. By using an optical delay device, the second polarized light is delayed for a predetermined time to obtain the delayed second polarized light; The delayed second polarized light is received by the beam splitting module, and a second pulse laser is output.

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