A kind of LD pumped Nd:YAG passively q-switched picosecond microchip laser generating device and method

Abstract

The application provides a kind of LD pumped Nd:YAG passive Q microchip laser generating device and method, adopts oscillation, amplification, frequency multiplication three-level structure, with compact structure, high efficiency, good stability characteristics.Through the adoption of specific doping concentration and initial transmittance Nd:YAG / Cr 4+ :YAG bonded crystal microchip cavity, and combined with optimized mode matching design, directly produces high quality, high repetition rate picosecond seed pulse, solves the problem of traditional microchip laser pulse width wide;Through the setting by dichroic mirror steering and double-sided LD symmetric pumping amplification crystal, seed pulse is amplified efficiently, significantly improves single pulse energy;Finally, after frequency multiplication, output hundred microjoule level, picosecond pulse width high brightness green laser, so as to successfully take into account high energy, narrow pulse width, high stability and compact, effectively solve the technical problems that picosecond laser source in the prior art is difficult to meet these performance indicators simultaneously.

Description

Technical Field

[0001] This invention relates to the field of solid-state laser technology, and in particular to an LD-pumped Nd:YAG passively Q-switched picosecond microchip laser generation device and method. Background Technology

[0002] All-solid-state picosecond pulsed lasers have important applications in precision machining, lidar, biomedicine, and scientific research. Currently, the mainstream approach to obtaining picosecond pulses is through mode-locked lasers and their subsequent amplification systems. While these systems can generate ultrashort pulses, their structures are typically extremely complex, containing multiple discrete optical components, resulting in large size and high cost. Furthermore, mode-locked lasers are highly sensitive to environmental disturbances, and their long-term operational stability is easily affected, making them unsuitable for industrial applications with stringent requirements regarding light source size, reliability, and cost.

[0003] Another promising approach is to employ a microchip laser structure. Traditional laser diode-pumped Nd:YAG / Cr... 4+ YAG passively Q-switched microchip lasers have secured a place in the field of micro-laser sources due to their compact structure, lack of active switching requirements, and high reliability. However, the output pulse width of this traditional structure is typically in the nanosecond range, making it difficult to enter the picosecond range. This is mainly because the energy storage characteristics of its gain medium, the recovery dynamics of the saturable absorber, and the thermal management and mode matching efficiency in traditional structures all limit further narrowing of the pulse width. Furthermore, limited by the gain volume of the microchip cavity, its single-pulse energy and peak power are also limited, failing to directly meet the application requirements of high-energy, narrow-pulse picosecond lasers. For example, in lidar, a narrower pulse width means higher range resolution; in precision machining, picosecond pulses can achieve a smaller heat-affected zone and higher machining accuracy.

[0004] Therefore, in this field, how to overcome the dual technical defects of existing picosecond laser sources, such as complex structure and poor stability, as well as the wide pulse width and low energy of traditional microchip lasers, and provide a new type of laser source that can achieve picosecond-level pulse width and high single-pulse energy output while maintaining the advantages of compactness and stability of microchip lasers, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide an LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generation device and method to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides an LD-pumped Nd:YAG passively Q-switched picosecond microchip laser generation device, comprising a pump source unit, a collimating and focusing optical unit, a laser oscillation unit, an amplification unit, and a frequency doubling unit arranged sequentially along the optical path;

[0008] The laser oscillation unit includes a bonded crystal and cavity mirror coatings located at both ends of the bonded crystal. The bonded crystal consists of an Nd:YAG gain dielectric portion and a Cr... 4+ The YAG saturable absorber is optically bonded along the optical axis and forms a linear resonant cavity with the cavity mirror coating, which is used to generate picosecond seed pulses when pumped.

[0009] The amplification unit includes a dichroic mirror and an amplifying crystal. The dichroic mirror is disposed in the output optical path of the laser oscillation unit and is used to reflect and redirect the picosecond seed pulse to the amplifying crystal. The amplifying crystal is an Nd:YAG crystal, which is pumped from the side by at least one second pump source and is used to amplify the energy of the picosecond seed pulse.

[0010] The frequency doubling unit includes a collimating lens and a frequency doubling crystal arranged sequentially along the optical path, used to convert the amplified infrared laser into visible light laser.

[0011] Preferably, in the bonded crystal, the Nd:YAG gain medium portion contains Nd... 3+ The doping concentration of the ions is 1.1 at.%; the Cr 4+ The initial transmittance T0 of the YAG saturable absorber portion is 30%; the transmittance of the output mirror of the linear resonant cavity to 1064nm laser is 50%±2%.

[0012] Preferably, the collimating and focusing optical unit is configured such that the pump spot radius formed by the pump light after being focused by it within the Nd:YAG portion of the bonded crystal is between 0.8 and 1.2 and the fundamental mode beam waist radius of the 1064nm laser in the linear resonant cavity.

[0013] Preferably, in the amplification unit, the dichroic mirror is highly transparent to 808nm pump light and highly reflective to 1064nm laser light; the amplifying crystal is symmetrically pumped from both sides by two identical second pump sources.

[0014] Preferably, the Nd in the amplified crystal 3+ The ion doping concentration is 0.6 at.%, and both of its light-transmitting end faces are coated with anti-reflection films for 808 nm and 1064 nm.

[0015] Preferably, in the frequency doubling unit, the frequency doubling crystal is a KTP nonlinear crystal, which is installed in an angle-adjustable adjustment device to meet the phase matching condition of doubling the 1064nm fundamental frequency light to 532nm green light.

[0016] Preferably, it further includes a thermal management unit, which includes a temperature control base and a TEC temperature control board; the bonding crystal and the amplification crystal are mounted on the temperature control base through a thermally conductive material, and the temperature control base is in close contact with the TEC temperature control board below.

[0017] Preferably, the picosecond seed pulse output by the laser oscillation unit has a pulse width on the order of 500 ps and a single pulse energy greater than 120 μJ; the single pulse energy of the pulse amplified by the amplification unit is greater than 400 μJ.

[0018] Preferably, the visible light laser output by the frequency doubling unit is 532nm green light, with a single pulse energy greater than 200μJ and a pulse width on the picosecond scale.

[0019] This invention also provides a method for generating a passively Q-switched picosecond microchip laser using an LD-pumped Nd:YAG microchip, comprising the following steps:

[0020] Pump light is provided to the bonding crystal in the laser oscillation unit through the pump source unit and the collimating and focusing optical unit;

[0021] Within the linear resonant cavity formed by the bonded crystal, a 1064nm picosecond seed pulse with high repetition rate and narrow pulse width is generated through a passive Q-switching mechanism.

[0022] The picosecond seed pulse is reflected by the dichroic mirror and injected into the amplifying crystal pumped from the second pump source side to amplify its energy.

[0023] The amplified 1064nm laser is collimated and then frequency-converted through the frequency doubling crystal, ultimately outputting a 532nm picosecond-level green light pulse.

[0024] The present invention achieves the following beneficial technical effects compared to the prior art:

[0025] This invention provides an LD-pumped Nd:YAG passively Q-switched picosecond microchip laser generation device and method, employing a three-stage structure of oscillation, amplification, and frequency doubling, featuring compact structure, high efficiency, and good stability. Specifically, it utilizes Nd:YAG / Cr with specific doping concentrations and initial transmittance... 4+By using a YAG-bonded crystal microcrystal cavity and optimized mode-matching design, high-quality, high-repetition-rate picosecond seed pulses were directly generated, solving the problem of wide pulse width in traditional microchip lasers. Furthermore, by setting up an amplifying crystal that is turned by a dichroic mirror and symmetrically pumped by dual-sided LDs, the seed pulses were efficiently amplified, significantly improving the single-pulse energy. Finally, after frequency doubling, a high-brightness green laser with a picosecond pulse width and a hundred-microjoule range was output, thus successfully balancing high energy, narrow pulse width, high stability, and compactness, effectively solving the technical challenge that existing picosecond laser sources cannot simultaneously meet these performance indicators. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A top view of the optical path structure of the LD-pumped Nd:YAG passively Q-switched picosecond microchip laser generation device provided by the present invention;

[0028] Figure 2 A perspective view of the optical path structure of the LD-pumped Nd:YAG passively Q-switched picosecond microchip laser generation device provided by the present invention;

[0029] Figure 3 A schematic diagram of the housing structure of the LD-pumped Nd:YAG passively Q-switched picosecond microchip laser generator provided by the present invention. Detailed Implementation

[0030] Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages). In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "beneath" of the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The purpose of this invention is to provide an LD-pumped Nd:YAG passively Q-switched picosecond microchip laser generation device and method. The device adopts a three-stage master oscillation power amplification structure of oscillation, amplification, and frequency doubling. High-quality picosecond seed pulses are generated by optimizing the parameters of the microchip oscillator, and then the energy is enhanced by the side-pumped amplification stage. Finally, the infrared laser is converted into high-brightness visible light laser by the frequency doubling unit.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1:

[0036] like Figure 1 The diagram shown is a schematic representation of the optical path structure of an LD-pumped Nd:YAG passively Q-switched picosecond microchip laser generation device according to an embodiment of the present invention. The device includes a pump source unit, a collimating and focusing optical unit, a laser oscillation unit, an amplification unit, and a frequency doubling unit arranged sequentially along the optical path. For ease of description, Figure 1The diagram also illustrates the optical path connections between the various units and the direction of light propagation. Specifically, the pump source unit includes a first pump source 1a, a second pump source 1b, and a third pump source 1c. In this embodiment, the first pump source 1a, the second pump source 1b, and the third pump source 1c are all semiconductor laser diodes with an output wavelength of 808 nanometers, used to generate pump light. The collimating and focusing optical unit includes collimating and focusing mirrors 2a, 2b, and 2c, each corresponding to a pump source. Each collimating and focusing mirror group includes one or more collimating mirrors for collimating and shaping the elliptical beam emitted by the laser diode, and a focusing lens for focusing the shaped pump light.

[0037] The laser oscillation unit is the core component for generating high-quality seed pulses. For example... Figure 1 As shown, the unit includes a bonded crystal 4 and cavity mirror coatings located at both ends of the bonded crystal 4. The bonded crystal 4 consists of a Nd:YAG (neodymium-doped yttrium aluminum garnet) moiety 4a as the gain medium and a chromium-doped yttrium aluminum garnet moiety 4a as the saturable absorber. 4+ The Nd:YAG portion 4b is formed by optical contact bonding along the optical axis. The two light-transmitting end faces of the bonded crystal 4 are directly coated with dielectric films of specific transmittance, thus forming a compact linear resonant cavity with the crystal itself, eliminating the need for additional discrete cavity mirrors. Specifically, the end face of the Nd:YAG portion 4a on the pump light incident side is coated with an anti-reflection film for 808 nm pump light and a high-reflection film for 1064 nm laser light, acting as an input mirror; the Cr portion on the output side... 4+ The end face of the Nd:YAG portion 4b is coated with a partially reflective film for 1064 nm laser light, serving as an output mirror. In this embodiment, the transmittance of the output mirror for 1064 nm laser light is set to approximately 50% to optimize the performance of the Q-switched switch and the output energy. The overall thickness of the bonded crystal 4 is between 5 mm and 10 mm, wherein the Nd:YAG portion 4a is bonded to the Cr... 4+ The thickness ratio of the YAG portion 4b is preferably 2:1 to 4:1.

[0038] To achieve picosecond-level narrow pulse output, the parameters of the bonded crystal were precisely designed. In this embodiment, the Nd in the Nd:YAG portion 4a... 3+ The doping concentration of the ions is 1.1 atomic percentage, while Cr 4+ The initial transmittance T0 of the YAG 4b portion is 30%. The synergistic effect of these two parameters, combined with the short cavity length design of the resonant cavity, enables the saturable absorber to be rapidly bleached and establishes extremely fast laser oscillation within the cavity, thereby outputting a 1064 nanometer picosecond seed pulse with a pulse width on the order of approximately 500 picoseconds and a single pulse energy greater than 120 microjoules.

[0039] To achieve good mode matching and ensure fundamental mode oscillation, the collimating and focusing optical unit is carefully configured. The 808 nm pump light emitted from the first pump source 1a is focused into the Nd:YAG portion 4a of the bonded crystal 4 after passing through the collimating and focusing lens 2a. The focal length of the focusing lens is chosen such that the ratio of the pump spot radius formed in this region to the fundamental mode beam waist radius of the 1064 nm laser in the linear resonant cavity, i.e., the mode matching ratio, is between 0.8 and 1.2. This near-matched or even slightly over-matched pumping method effectively suppresses the onset of higher-order modes, ensuring excellent beam quality for the seed pulse.

[0040] The amplification unit is used to boost the energy of the seed pulse. For example... Figure 1 As shown, the 1064 nm seed pulse output from the laser oscillation unit is first incident on a dichroic mirror 3b. This dichroic mirror 3b has high transmittance for the 808 nm pump light and high reflectivity for the 1064 nm laser, thus efficiently redirecting the seed pulse's optical path by 90 degrees, allowing it to be incident perpendicularly into the magnifying crystal 5. The magnifying crystal 5 is another Nd:YAG crystal, whose Nd... 3+ The ion doping concentration is 0.6 atomic percent, and the geometric dimensions are 3 mm × 3 mm × 10 mm. Both of its light-transmitting end faces are coated with anti-reflection films for 808 nm and 1064 nm to reduce insertion loss. To provide sufficient gain to the amplifying crystal 5, two identical second pump sources 1b and third pump sources 1c are used to symmetrically pump it from both sides. The emitted light from these two pump sources is coupled into the amplifying crystal 5 through their respective collimating focusing lenses 2b and 2c. In terms of timing control, the pump pulses of the second pump source 1b and the third pump source 1c are precisely synchronized with the seed pulse from the oscillation unit, ensuring that when the seed light passes through, the neodymium ions in the amplifying crystal 5 are in the optimal inverted particle number state. When the seed light with a pulse width on the order of 500 picoseconds passes through the amplifying crystal 5 in a high-gain state, its energy is significantly amplified through stimulated emission. After optimization, this embodiment can obtain a 1064 nm laser with a single pulse energy greater than 400 microjoules and good maintenance of pulse width and beam quality at the output end of the amplifying crystal 5.

[0041] The frequency doubling unit is used to convert the amplified infrared laser into more widely used visible light. The high-energy 1064 nm laser emitted from the amplifying crystal 5 is first incident on the dichroic mirror 3c and then redirected by 90 degrees. The redirected beam is then collimated by a collimating lens 6, preferably with a focal length of 60 mm, to form a parallel beam with a suitable diameter and a small divergence angle. This parallel beam is then perpendicularly incident on the frequency doubling crystal 7 after passing through the dichroic mirror 3d. In this embodiment, the frequency doubling crystal 7 is a type II phase-matched potassium titanate oxyphosphate (KTP) nonlinear crystal with dimensions of 2 mm × 2 mm × 8 mm. Both light-transmitting end faces are coated with dual-wavelength anti-reflection films for 1064 nm and 532 nm. To obtain the highest conversion efficiency, the frequency doubling crystal 7 is mounted on an angle-adjustable adjustment device. By precisely adjusting its angle and combining it with a temperature control device to accurately control its temperature, the optimal phase-matching conditions for doubling the 1064 nm fundamental frequency light to 532 nm green light are achieved. When a 1064 nm picosecond pulse with a sufficiently high peak power density passes through the KTP crystal 7, a second-order nonlinear frequency upconversion occurs, generating 532 nm green light. Following the frequency doubling crystal 7, a filter 9 is placed to filter out residual 1064 nm fundamental frequency light, ultimately outputting a high-purity 532 nm green laser 10. Verification shows that, under a pump power of 2.3 watts, the device in this embodiment outputs a 532 nm laser with a single pulse energy greater than 200 microjoules, a pulse width maintained in the picosecond range, and a repetition frequency reaching 1 kHz.

[0042] In addition, to ensure the long-term stable operation of the laser, this device also includes a thermal management unit. For example... Figure 1 and Figure 2 As shown, the thermal management unit includes a temperature control base 8 and a TEC temperature control board. The temperature control base 8 is made of aluminum alloy 6061, which has good thermal conductivity. The bonding crystal 4 and the amplifying crystal 5 are mounted on the temperature control base 8 using thermally conductive materials such as thermal grease. A semiconductor cooler (TEC) temperature control board is attached directly to the bottom of the temperature control base 8. This TEC temperature control board is connected to the control circuit, and its operating temperature is precisely controlled by the host computer software. In this embodiment, the operating temperature of the bonding crystal 4 is stably controlled at 35 ± 0.1 degrees Celsius, while the operating temperature of the frequency doubling crystal 7 and the base temperature of the TEC temperature control board are controlled at around 25 degrees Celsius. This active temperature control method effectively eliminates the thermal lensing effect and crystal performance drift caused by the pump photothermal effect, ensuring the energy and pointing stability of the laser output.

[0043] Based on the above-mentioned device, the present invention also provides a method for generating a passively Q-switched picosecond microchip laser using an LD-pumped Nd:YAG microchip. In one specific embodiment, the method includes the following steps: First, a first pump source 1a, a second pump source 1b, and a third pump source 1c are activated. The 808 nm pump light emitted by these sources is collimated and focused by their respective collimating and focusing lens groups and then acts on the bonding crystal 4 and the amplifying crystal 5, respectively. In the laser oscillation unit, the pump light from the first pump source 1a is absorbed by the Nd:YAG portion 4a of the bonding crystal 4, and population inversion gradually accumulates. Due to the initial state of Cr... 4+ The 4b portion of the YAG laser is in a high-loss state, suppressing laser oscillation. When the inverted particle number accumulates to the bleaching threshold of the saturable absorber, the Q-switch suddenly opens, and extremely strong laser oscillation is rapidly established within the cavity, originating from Cr. 4+ The YAG section at end 4b directly emits a 1064 nm picosecond seed pulse with a pulse width of approximately 500 picoseconds and a single-pulse energy greater than 120 microjoules. Subsequently, this seed pulse is reflected and redirected by the dichroic mirror 3b, and then vertically injected into the amplifying crystal 5, which is symmetrically pumped from both sides by the second pump source 1b and the third pump source 1c. The pump timing is adjusted to ensure that the amplifying crystal 5 is in a high-gain state when the seed pulse arrives, and the seed light energy is significantly amplified through stimulated emission, outputting a 1064 nm laser with a single-pulse energy greater than 400 microjoules. Finally, this amplified infrared laser is collimated by the collimating lens 6 and incident on the KTP frequency doubling crystal 7, which meets the phase-matching condition. Through nonlinear frequency conversion, it is converted into a 532 nm picosecond green laser 10 with a single-pulse energy greater than 200 microjoules.

[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] It should be noted that the components mentioned in the above embodiments are all general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0046] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.

Claims

1. A device for generating a passively Q-switched picosecond microplate laser using an LD-pumped Nd:YAG laser, characterized in that, It includes a pump source unit, a collimating and focusing optical unit, a laser oscillation unit, an amplification unit, and a frequency doubling unit arranged sequentially along the optical path; The laser oscillation unit includes a bonded crystal and cavity mirror coatings located at both ends of the bonded crystal. The bonded crystal consists of an Nd:YAG gain dielectric portion and a Cr... 4+ The YAG saturable absorber is optically bonded along the optical axis and forms a linear resonant cavity with the cavity mirror coating, which is used to generate picosecond seed pulses when pumped. The amplification unit includes a dichroic mirror and an amplifying crystal. The dichroic mirror is disposed in the output optical path of the laser oscillation unit and is used to reflect and redirect the picosecond seed pulse to the amplifying crystal. The amplifying crystal is an Nd:YAG crystal, which is pumped from the side by at least one second pump source and is used to amplify the energy of the picosecond seed pulse. The frequency doubling unit includes a collimating lens and a frequency doubling crystal arranged sequentially along the optical path, used to convert the amplified infrared laser into visible light laser.

2. The LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generating device according to claim 1, characterized in that, In the bonded crystal, the Nd:YAG gain medium portion contains Nd 3+ The doping concentration of the ions is 1.1 at.%; the Cr 4+ The initial transmittance T0 of the YAG saturable absorber portion is 30%; the transmittance of the output mirror of the linear resonant cavity to 1064nm laser is 50%±2%.

3. The LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generating device according to claim 1, characterized in that, The collimating and focusing optical unit is configured such that the pump spot radius formed by the pump light after being focused by it within the Nd:YAG portion of the bonded crystal is between 0.8 and 1.2, and the ratio of the fundamental mode beam waist radius of the 1064nm laser in the linear resonant cavity is between 0.8 and 1.

2.

4. The LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generating device according to claim 1, characterized in that, In the amplification unit, the dichroic mirror is highly transparent to 808nm pump light and highly reflective to 1064nm laser light; the amplifying crystal is symmetrically pumped from both sides by two identical second pump sources.

5. The LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generating device according to claim 1, characterized in that, Nd in the magnified crystal 3+ The ion doping concentration is 0.6 at.%, and both of its light-transmitting end faces are coated with anti-reflection films for 808 nm and 1064 nm.

6. The LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generating device according to claim 1, characterized in that, In the frequency doubling unit, the frequency doubling crystal is a KTP nonlinear crystal, which is installed in an angle-adjustable adjustment device to meet the phase matching condition of doubling the 1064nm fundamental frequency light to 532nm green light.

7. The LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generating device according to claim 1, characterized in that, It also includes a thermal management unit, which includes a temperature control base and a TEC temperature control board; the bonding crystal and the amplification crystal are mounted on the temperature control base through a thermally conductive material, and the temperature control base is in close contact with the TEC temperature control board below.

8. The LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generating device according to claim 1, characterized in that, The picosecond seed pulse output by the laser oscillation unit has a pulse width on the order of 500 ps and a single pulse energy greater than 120 μJ; the single pulse energy of the pulse amplified by the amplification unit is greater than 400 μJ.

9. The LD-pumped Nd:YAG passively Q-switched picosecond microplate laser generating device according to claim 1, characterized in that, The frequency doubling unit ultimately outputs 532nm green light, with a single pulse energy greater than 200μJ and a pulse width on the picosecond scale.

10. A method for generating an LD-pumped Nd:YAG passively Q-switched picosecond microchip laser based on any one of claims 1 to 9, characterized in that, Includes the following steps: Pump light is provided to the bonding crystal in the laser oscillation unit through the pump source unit and the collimating and focusing optical unit; Within the linear resonant cavity formed by the bonded crystal, a 1064nm picosecond seed pulse with high repetition rate and narrow pulse width is generated through a passive Q-switching mechanism. The picosecond seed pulse is reflected by the dichroic mirror and injected into the amplifying crystal pumped from the second pump source side to amplify its energy. The amplified 1064nm laser is collimated and then frequency-converted through the frequency doubling crystal, ultimately outputting a 532nm picosecond-level green light pulse.

Images