Narrow pulse width multi-wavelength laser based on LED pumping

Abstract

A narrow-pulse-width multi-wavelength laser based on LED pumping comprises a reflecting mirror, a first LED pumping module, an optical rotation crystal, a second LED pumping module, an acousto-optic Q-switched crystal and an output mirror which are sequentially connected in series. The LED pumping module comprises a laser rod located in the center, a glass sleeve is arranged on the periphery of the laser rod in the length direction, a supporting frame is arranged on the periphery of the glass sleeve, a plurality of sets of water-cooling copper blocks are evenly arranged on the supporting frame, and an LED stacking array is arranged on the side, close to the glass sleeve, of each set of water-cooling copper blocks. Each LED stacking array comprises an LED light bar and a PCB (Printed Circuit Board) for fixing the LED light bar, and the PCB is connected with the water-cooling copper block; cooling water circulation modules are arranged at the two ends of the laser rod in the length direction respectively, and water through holes are formed in the cooling water circulation modules and the water cooling copper blocks respectively. A laser resonant cavity system of the laser takes an LED as a pumping source, combines an acousto-optic Q-switching technology, and simultaneously realizes compression of laser pulse width and multi-wavelength output.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, and in particular to a narrow pulse width multi-wavelength laser based on LED pumping. Background Art

[0002] It is well known that by controlling the loss of different transition spectral lines in the resonant cavity to meet their threshold conditions, the net gain can be balanced, and at this time, it is expected to achieve simultaneous output of multi-wavelength lasers. The threshold pump power is related to factors such as the reflectivity of the output mirror, the round-trip loss in the cavity, the stimulated emission cross section, and the overlap of the pump light and the oscillating light. Therefore, by controlling the above factors, multi-wavelength lasers can be generated simultaneously.

[0003] (1) Changing the reflectivity of the output mirror to achieve multi-wavelength laser output When the resonant cavity parameters are determined, the threshold pump power of different wavelengths is related to the reflectivity of the output mirror. Therefore, the reflectivity of the output mirror can be changed to control the threshold pump power of different wavelengths, thereby achieving simultaneous generation and output of multi-wavelength lasers. Specifically, the reflectivity of the output mirror can be adjusted by applying a specific coating to the output mirror or by using an FP filter (FPF) as the output mirror.

[0004] For example, the laser system achieves gain balance of two wavelengths by using two FPFs. The first FPF is used to suppress 1064nm and enhance 1085nm output, and the second FPF is used to transmit as much 1085nm laser as possible and achieve 1064nm laser oscillation, thereby achieving 1064nm / 1085nm dual-wavelength laser output.

[0005] (2) Adjusting the loss in the resonant cavity to achieve multi-wavelength laser output When the parameters of the resonant cavity are determined, the threshold pump power of different wavelengths is related to the corresponding intracavity loss. The greater the intracavity loss, the greater the threshold pump power. Therefore, the intracavity loss of different wavelengths can be changed to control the threshold pump power, thereby achieving dual-wavelength laser output. Specific methods include inserting an etalon or a birefringent filter (BRF) into the resonant cavity.

[0006] For example, in a laser system, the transmittance of BRF to different wavelengths is related to the angle θ at which the laser is incident on BRF. B Therefore, the dual-wavelength laser output can be achieved by rotating the BRF to control the loss of different wavelengths in the resonant cavity. The system can ultimately achieve dual-wavelength laser output with three wavelength combinations of 869nm&915nm, 894nm&915nm, and 915nm&923nm.

[0007] (3) Controlling the stimulated emission cross section to achieve multi-wavelength laser output When the resonant cavity parameters are determined, the threshold pump power of different wavelengths is related to the corresponding stimulated emission cross section. If the stimulated emission cross section can be changed, the threshold pump power of different wavelengths can be changed, thereby achieving dual-wavelength laser output. The specific method can be achieved by changing the angle between the laser propagation direction and the crystal axis. to change the stimulated emission cross section.

[0008] For example, in the birefringent crystal Nd:YLF, the laser light will be split into Light and Light, when the angle When changing, Stimulated emission cross section Will follow change, Stimulated emission cross section remains unchanged. Change to a certain angle When At this time, when the resonant cavity parameters are determined, the threshold pump powers of the two are equal, so dual-wavelength laser output can be achieved. The emission cross sections of 1047nm and 1053nm are balanced by using the polarization direction at 50.3° with the crystal optical axis, achieving dual-wavelength laser output at 1047nm and 1053nm.

[0009] The existing technology has obvious deficiencies in terms of multi-wavelength output, stability, tuning flexibility, pump efficiency and scalability, including the following issues: (1) Gain competition problem: In existing multi-wavelength lasers, lasers of different wavelengths are prone to gain competition, resulting in suppression or instability of output of certain wavelengths.

[0010] (2) Insufficient tuning flexibility: Traditional multi-wavelength lasers have slow tuning speeds, difficult synchronization adjustments, and low tuning accuracy due to their reliance on mechanical gratings or intracavity optical elements and limitations of the gain mechanism.

[0011] (3) Thermal management issues: Under high LD pump density, the thermal effects inside the laser crystal will seriously weaken the beam quality, reduce the power and stability of the dual-wavelength output, and therefore require efficient thermal management capabilities.

[0012] (4) Poor system scalability: In existing technologies, the structural design of multi-wavelength lasers is often targeted at specific applications, lacking modularity and scalability, and making it difficult to cover different wavelength ranges.

[0013] (5) High overall cost: Traditional multi-wavelength lasers require precise wavelength tuning component configuration, special laser cavity mirror film design, and high-performance pump sources, resulting in high manufacturing costs and difficult maintenance. Summary of the invention

[0014] The invention provides a narrow pulse width multi-wavelength laser based on LED pumping. The laser resonant cavity system of the laser uses LED as a pump source and combines acousto-optic Q-switching technology to achieve laser pulse width compression and multi-wavelength output at the same time.

[0015] A narrow pulse width multi-wavelength laser based on LED pumping comprises a reflector, a first LED pumping module, an optical rotation crystal, a second LED pumping module, an acousto-optic Q-switched crystal and an output mirror which are sequentially connected in series.

[0016] Preferably, the reflector of the present invention is a 0° plane reflector, which is located at the left end of the cavity and is used to reflect the light beam in the cavity to form a resonant cavity, thereby providing multiple round-trip amplification conditions for the laser.

[0017] Preferably, the specific structure of the first LED pump module and the second LED pump module of the present invention is as follows: comprising a laser rod located at a central position, a glass sleeve arranged on the periphery of the laser rod in the length direction, a support frame arranged on the periphery of the glass sleeve, a plurality of groups of water-cooled copper blocks evenly arranged on the support frame, an LED stacking array arranged on a side of each group of water-cooled copper blocks close to the glass sleeve, each LED stacking array comprising an LED light bar and a PCB board for fixing the LED light bar, and the PCB board connected to the water-cooled copper block; Cooling water circulation modules are respectively arranged at both ends of the laser rod in the length direction, and water holes are respectively arranged on the cooling water circulation module and the water-cooled copper block.

[0018] Preferably, each LED light strip of the present invention includes 20 LED lamp beads forming a row of LED stacked arrays, the LED lamp beads are SMD LEDs, the emission center wavelength is 810nm, the half-peak width is about 30nm, and the beam angle is 90°.

[0019] Preferably, the operating frequency of the LED of the present invention is 100 Hz, and the pulse duty cycle is 20%.

[0020] Preferably, the gain medium of the first LED pump module of the present invention is neodymium-doped yttrium aluminum garnet (Nd:YAG); both ends are sealed in the cooling water circulation module, and the neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal is excited by the LED light source to provide a gain with a wavelength of 1064nm. Preferably, the gain medium of the second LED pump module of the present invention is neodymium-doped yttrium lithium fluoride (Nd:YLF), both ends of which are sealed in a cooling water circulation module, and the neodymium-doped yttrium lithium fluoride (Nd:YLF) crystal is excited by an LED light source to provide gain at wavelengths of 1047nm and 1053nm. Preferably, the acousto-optic Q-switched crystal of the present invention is used to form a Bragg diffraction grating by utilizing the periodic refractive index variation generated in the crystal by ultrasonic waves through the acousto-optic effect.

[0021] Preferably, the output mirror of the present invention is used as a partially transmitting mirror to couple out a portion of the intracavity light beam and reflect the remaining light beam to continue oscillating in the resonant cavity.

[0022] The present invention combines two different gain media (Nd:YAG and Nd:YLF) through intracavity seed injection technology, and utilizes active Q-switching technology and the design of an LED pump module composed of an LED stack array to achieve stable output of multi-wavelength narrow pulse width lasers. The technical effects and beneficial improvements are as follows: 1. Realize simultaneous output of multiple wavelengths The present invention utilizes the different gain peaks of Nd:YAG and Nd:YLF gain media and combines intracavity seed injection technology to accurately control the gain distribution of 1047 nm, 1053 nm and 1064 nm wavelengths, avoiding the limitation of single-wavelength oscillation in traditional lasers and significantly improving the functionality and applicability of the output.

[0023] 2. Enhance system stability (1) Output wavelength stability The seed injection technology effectively suppresses the gain competition in multi-wavelength output. By artificially enhancing the initial oscillation intensity of each wavelength, it ensures the energy balance between different wavelengths, thereby achieving long-term and stable multi-wavelength laser output.

[0024] (2) Output power stability The wide spectrum and high uniformity of LED light make the pump light energy distribution more uniform, reduce the unevenness of heat load distribution, inhibit the interference of thermal effects on laser output, and ensure the long-term operation stability of the system. The system uses acousto-optic Q-switched crystals to achieve precise pulse control, avoid pulse width and frequency fluctuations, and improve the power stability of the output laser.

[0025] 3. High beam quality and narrow pulse width characteristics The low heat load characteristics brought by LED pumping significantly reduce the impact of thermal lens effect and thermal stress on beam quality, thereby improving the mode purity and stability of the laser beam. The pump light energy distribution in the gain medium is more uniform, which reduces the distortion problem of the output beam and improves the spatial quality factor of the beam. In addition, the present invention combines active Q-switching technology to maintain narrow pulse width characteristics while outputting multiple wavelengths and optimize the mode quality of the output beam. This feature is very suitable for application scenarios that require high precision, such as lidar, precision measurement, and micromachining.

[0026] 4. Improve the system’s tuning capabilities The use of two gain media, Nd:YAG and Nd:YLF, has complementary gain characteristics, which can achieve the expansion of gain bandwidth and improve the efficiency and flexibility of laser output. The gain medium can be dynamically adjusted according to the distribution of pump power to balance the output power of lasers of different wavelengths, thereby achieving better gain matching and energy distribution. The present invention can quickly achieve the tuning of multi-wavelength output by adjusting the wavelength of the seed light source or the operating parameters of the pump module (such as current or temperature), meeting the demand for wavelength flexibility in different scenarios.

[0027] 5. Increase output power The laser achieves multi-wavelength synchronous output and significantly improves output power by combining dual-gain media (Nd:YAG and Nd:YLF) with high-efficiency LED side pumping technology. The dual-gain medium optimizes energy utilization, reduces energy competition between wavelengths, and synergistically releases higher power; LED wide-spectrum pumping improves light absorption efficiency, reduces thermal effects, and improves pump energy conversion efficiency; at the same time, the design of reducing optical losses in the cavity optimizes mode matching and energy distribution, and improves output power.

[0028] 6. Wide application adaptability The LED pump module and independent gain medium structure design are adopted. Each module is independent and replaceable, which is convenient for system installation, maintenance and expansion. Without changing the core structure, the operating wavelength range and power output capacity of the system can be expanded by replacing the LED pump module or gain medium.

[0029] The dual-gain medium design allows the system to easily add other gain materials to achieve laser output with more wavelengths, and has strong adaptability and scalability, which makes it have significant application value in laser communications, spectral analysis, multi-wavelength holographic imaging and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the laser resonant cavity system of the present invention.

[0031] Figure 2 It is a cross-sectional schematic diagram of the LED pump module of the present invention.

[0032] Figure 3 It is a schematic longitudinal section diagram of the LED pump module of the present invention. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described in detail below with reference to the accompanying drawings: like Figure 1As shown, a narrow pulse width multi-wavelength laser based on LED pumping includes a reflector 1, a first LED pumping module 2, an optical rotation crystal 3, a second LED pumping module 4, an acousto-optic Q-switched crystal 5, and an output mirror 6 which are connected in series in sequence.

[0034] The detailed laser propagation path is shown below: 1. Initial light generation (1) Injection of pump light (for the first LED pump module 2 and the second LED pump module 4) The laser uses a side pumping mode, and the gain medium in the first LED pump module 2 and the second LED pump module 4 is the pumping region. External pump light (LED emission) is injected from the side of the gain medium. The pump light is absorbed by the gain medium, causing the energy level of the doped ions inside to transition to a high energy state. A portion of the high energy state ions transition to the laser working energy level through radiative relaxation or non-radiative relaxation, establishing a population inversion condition in the gain medium.

[0035] Initial light generation The generation of initial light depends on the noise photons (spontaneous radiation) in the cavity, which are reflected back to the gain medium through the reflector 1. In the gain medium, these photons interact with high-energy particles through stimulated radiation, inducing more photons to be emitted with the same frequency, phase and propagation direction, thereby achieving light amplification.

[0036] 2. Laser propagation in the resonant cavity (1) Optical amplification process The spontaneously emitted photons are reflected by the reflector 1 and enter the gain medium in the first LED pump module 2 and the second LED pump module 4, where stimulated radiation occurs and the beam energy is amplified. The population inversion in the gain medium is continuously maintained to ensure that the laser beam continues to be amplified when passing through. The amplified beam continues to propagate to the right and enters the acousto-optic Q-switched crystal 5.

[0037] (2) Q-switching process The laser passes through the acousto-optic Q-switched crystal 5. In the low Q value state, the switch reduces the loss of the resonant cavity and stores energy; when switched to the high Q value state, the switch releases the light energy accumulated in the cavity to form a high peak value pulse laser.

[0038] 3. Laser output The laser transmitted from the output mirror 6 is the final laser output beam. The output mirror 6 can transmit a portion of the laser energy as an output beam, and reflect the remaining portion back into the cavity to continue oscillating.

[0039] like Figure 2 , 3As shown, the specific structure of the LED pump module of the present invention is as follows: it includes a laser rod 7 located at the center, a glass sleeve 8 is arranged on the periphery of the laser rod 7 in the length direction, a support frame 9 is arranged on the periphery of the glass sleeve 8, a plurality of groups of water-cooled copper blocks 10 are evenly arranged on the support frame 9, an LED stacking array is arranged on one side of each group of water-cooled copper blocks 10 close to the glass sleeve, each LED stacking array includes an LED light bar 11 and a PCB board 12 for fixing the LED light bar, and the PCB board is connected to the water-cooled copper block; Cooling water circulation modules 13 are respectively arranged at both ends of the laser rod in the length direction, and water holes 14 are respectively arranged on the cooling water circulation module 13 and the water-cooled copper block 10 .

[0040] The structural features of the present invention are specifically: 1. LED as a pump source Compared with LD pumping, LED pumping has obvious advantages in cost, thermal effect, wavelength adaptability and beam quality, and is particularly suitable for multi-wavelength narrow pulse width laser systems or scenes that are sensitive to thermal effects. Specifically, it has the following advantages: (1) Improving pump light coupling efficiency LED light has a wide spectrum and a large divergence angle, but through a specially designed side pumping device, the LED light can be uniformly injected into the gain medium, thereby improving the overall pumping efficiency. The wide-angle emission characteristics of the LED light source provide better coverage uniformity in the pumping area, avoiding the problem of excessive local photon density, and helping to improve the uniformity of the interaction between light and the gain medium. Although traditional LD ​​pumping has high beam quality and directionality and high coupling efficiency, the coupling alignment requirements are extremely strict, and a slight deviation will lead to a decrease in efficiency.

[0041] (2) Reduce the thermal effect inside the laser crystal The luminous power density of LED is lower than that of LD, so the power density injected into the gain medium is lower, the heat generated is more dispersed, the heat load is more uniform, and the temperature gradient in the laser crystal can be significantly reduced. The smaller thermal effect helps to reduce the thermal lens effect and thermally induced birefringence effect, thereby improving the beam quality and power stability. The high power density of traditional LD ​​pumping will cause heat accumulation in the local area of ​​the gain medium, forming a large temperature gradient, which will cause serious thermal effect problems, such as thermal lens effect, thermal stress effect and beam distortion, reducing beam quality and output stability. Therefore, a complex thermal management system is usually required to mitigate thermal effects, but this will increase system complexity and cost.

[0042] (3) Better working wavelength adaptability LEDs have broad spectrum emission characteristics, which can better cover the absorption peak of the gain medium, thereby more efficiently achieving multi-wavelength pumping or broad spectrum laser output in a specific design. However, the narrow spectrum emission of LDs is poorly adaptable to broad absorption bands, limiting flexibility.

[0043] (4) Significantly reduce the manufacturing cost of laser systems Compared with LD, LED light source has lower cost, mature manufacturing technology and is easy to mass produce. LED driving and control circuits are simple (external power supply adopts low current and high voltage power supply mode), lower power consumption, and significantly reduced total system cost. In addition, it has a long service life, low maintenance cost, and higher comprehensive cost performance.

[0044] (5) Better environmental adaptability LED has lower requirements for the working environment, is more resistant to high temperatures and shocks, and is suitable for laser system applications in complex environments. However, traditional LD ​​pumps are sensitive to external conditions such as temperature and vibration, have higher requirements for the operating environment, and require additional protection measures and constant temperature control.

[0045] 2. Film selection for reflector and output coupling mirror In order to make the three selected wavelengths of laser (1047nm, 1053nm, 1064nm) oscillate simultaneously in the resonant cavity and maintain stable output, it is necessary to select a reflector and coupling output mirror film system with a wide bandwidth (1040nm~1070nm). The film system design of traditional LD ​​pumped multi-wavelength lasers requires precise control of the reflectivity of the reflector corresponding to the oscillation wavelength and the transmittance of the coupling output mirror.

[0046] 3. Realize multi-wavelength by intracavity seed injection Through intracavity seed injection, the competition effect between different wavelengths can be suppressed, and the laser can stably output multiple wavelengths. The advantages of using intracavity seed injection to generate multi-wavelength lasers include the following: (1) High-efficiency wavelength selection and stability Intracavity seed injection technology can significantly reduce the mode competition between different wavelengths and effectively enhance the oscillation of a specific wavelength. This method can ensure the stable output of multiple wavelengths by precisely controlling the injection intensity of the seed light (1064nm) and avoid the single wavelength output problem caused by wavelength competition.

[0047] (2) Fast tuning capability By adjusting the power supply or temperature control parameters of the gain module, the multi-wavelength output can be quickly switched or adjusted, making the laser more flexible in use and adapting to application scenarios with different wavelength requirements.

[0048] (3) System scalability By replacing the gain medium, it can be expanded to other wavelength regions to meet the multi-wavelength output requirements of different application scenarios.

[0049] (4) Streamlined system design Multi-wavelength tuning is achieved through a simple light source without complex intracavity structures or additional wavelength selection elements. Traditional LD-pumped dual-wavelength lasers usually require multiple gain media or special resonant cavities, which are complex in design and difficult to adjust.

[0050] The laser resonant cavity system of the present invention uses LED as a pump source and combines acousto-optic Q-switching technology to achieve laser pulse width compression and multi-wavelength output. The structure of the laser resonant cavity system is as follows: Figure 1 As shown. Following the optical path starting from the reflector, the following is a detailed description: (1) 0° plane mirror 1: Located at the left end of the cavity, it is used to reflect the light beam in the cavity to form a resonant cavity and provide multiple round-trip amplification conditions for the laser.

[0051] (2) LED pump module: The two LED pump module devices of the present invention are identical except for the gain medium. The cross-section and longitudinal section of a single LED pump module are as follows: Figure 2 , Figure 3 The following is a detailed description of a single LED pump module: a. The LED lamp beads are SMD LEDs with an emission center wavelength of 810nm, a half-peak width of about 30nm, and a beam angle of 90°. 20 LED lamp beads form a row of LED stacked arrays, and five rows of LED stacked arrays form a side pump source, which is fixed on the support frame of the cavity and evenly arranged around the crystal rod, thereby enhancing the uniformity of the pump and reducing the thermal effect on the crystal rod. In order to optimize the performance of the LED pump module, the LED operates at a frequency of 100Hz and a pulse duty cycle of 20%. At the same time, in order to ensure the stability of the LED pump, the LED array is close to the water-cooled copper block, and the cooling water passes through the water hole to keep the temperature of the copper block stable at around 3°C.

[0052] b. The gain medium (crystal rod) is Nd:YAG (neodymium-doped yttrium aluminum garnet). Both ends of the gain medium are sealed in a module with a cooling water circulation structure. The cooling water passes through the water cooling channel between the glass sleeve and the crystal rod to keep the crystal rod temperature at around 17°C.

[0053] c. The gain medium (crystal rod) of the first LED pump module 2 is neodymium-doped yttrium aluminum garnet (Nd:YAG). The Nd:YAG crystal is excited by the LED pump source to achieve energy level transition of the laser working material, providing gain at a wavelength of 1064nm as a gain source in the resonant cavity.

[0054] The gain medium (crystal rod) of the second LED pump module 4 is neodymium-doped yttrium lithium fluoride (Nd:YLF). The Nd:YLF crystal is excited by the LED pump source to provide gain at another two wavelengths of 1047 nm and 1053 nm, and realize multi-wavelength laser output with Nd:YAG to expand the wavelength range of the laser.

[0055] (3) Optically active crystal 3: It adjusts the polarization state of the light beam so that the thermally induced birefringence effects of the two laser rods cancel each other out in the cavity, thus avoiding the accumulation of polarization state distortion and eliminating the influence of the thermally induced birefringence effect.

[0056] (4) Acousto-optic Q-switched crystal 5: The periodic refractive index change caused by ultrasound in the crystal is used through the acousto-optic effect to form a Bragg diffraction grating. When the laser passes through the crystal, the loss in the laser cavity can be adjusted by controlling the on and off of the ultrasound, thereby achieving rapid modulation of the laser oscillation. Its main function is to adjust the quality factor (Q value) of the laser, accumulate energy in the high Q state, and quickly release it in the low Q state, thereby outputting a pulsed laser with high peak power. This part is used to optimize the pulse characteristics of the laser output.

[0057] (5) Output mirror 6: As a partially transmitting mirror, it couples part of the intracavity beam out and reflects the remaining beam to continue oscillating in the resonant cavity.

[0058] The working mechanism of the multi-wavelength tunable laser of the present invention is as follows: 1. Multi-wavelength characteristics of gain medium: The main emission wavelength of Nd:YAG is 1064nm, which is its strongest transition wavelength. At the same time, it can also support other secondary wavelengths such as 946nm under certain conditions. For the 1064nm wavelength, Nd:YAG provides high gain amplification. The emission spectrum of Nd:YLF is different from that of Nd:YAG, and it mainly emits two wavelengths: 1047nm (corresponding to Polarized light) and 1053nm (corresponding to Polarized light). The combination of these two gain media forms a composite gain spectrum covering the gain regions of 1047nm, 1053nm and 1064nm, laying the foundation for multi-wavelength output.

[0059] 2. Energy coupling mechanism in the resonant cavity: The wavelengths of 1064nm of Nd:YAG and 1053nm of Nd:YLF are close. When they propagate in the cavity, they will enhance the stability of oscillation through the spatial and temporal superposition of the light field. Especially in the absence of polarization selective devices, Nd:YAG has a very high gain coefficient at the wavelength of 1064nm, which will produce a strong laser light field. This strong light field can interact with the gain medium of Nd:YLF through multiple reflections in the cavity, thereby stimulating the transition of 1053nm. This coupling will enhance the number of photons with a wavelength of 1053nm, prompting it to quickly reach the threshold and enter the oscillation state. Specifically, the energy level distribution between the 1053nm energy level transition of Nd:YLF and the 1064nm energy level transition of Nd:YAG is relatively close, and the "pulling effect" of the laser light field on the gain band of Nd:YLF will make it easier for 1053nm to reach the threshold.

[0060] 3. The independence of different gain media is the main reason for the weakening of intracavity mode competition. The gain spectra of Nd:YLF and Nd:YAG do not completely overlap, and they each have a specific gain center wavelength, which means that the two media mainly provide gain support for different wavelengths, enhancing the stability of multi-wavelength output.

[0061] The present invention significantly improves the multi-wavelength output capability, stability and flexibility of the laser by innovatively combining intracavity seed injection, dual gain medium and LED pumping technology, while maintaining the characteristics of high efficiency and high power output, and has broad practicality and technical advantages.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A narrow pulse width multi-wavelength laser based on LED pumping, characterized in that The invention comprises a reflector, a first LED pump module, an optical rotation crystal, a second LED pump module, an acousto-optic Q-switching crystal and an output mirror which are connected in series in sequence.

2. The LED-pumped narrow pulse width multi-wavelength laser according to claim 1, characterized in that The above-mentioned reflector is a 0° plane reflector, which is located at the left end of the cavity and is used to reflect the light beam in the cavity to form a resonant cavity and provide multiple round-trip amplification conditions for the laser.

3. The LED-pumped narrow pulse width multi-wavelength laser according to claim 1, characterized in that The specific structure of the first LED pump module and the second LED pump module is as follows: comprising a laser rod located at a central position, a glass sleeve arranged on the periphery of the laser rod in the length direction, a support frame arranged on the periphery of the glass sleeve, a plurality of groups of water-cooled copper blocks evenly arranged on the support frame, an LED stacking array arranged on a side of each group of water-cooled copper blocks close to the glass sleeve, each LED stacking array comprising an LED light bar and a PCB board for fixing the LED light bar, and the PCB board is connected to the water-cooled copper block; Cooling water circulation modules are respectively arranged at both ends of the laser rod in the length direction, and water holes are respectively arranged on the cooling water circulation module and the water-cooled copper block.

4. The LED-pumped narrow pulse width multi-wavelength laser according to claim 3, characterized in that Each of the above-mentioned LED light strips includes 20 LED lamp beads to form a row of LED stacked arrays. The LED lamp beads are surface-mount LEDs with an emission center wavelength of 810nm, a half-peak width of 30nm, and a beam angle of 90°.

5. The LED-pumped narrow pulse width multi-wavelength laser according to claim 4, characterized in that The operating frequency of the above LED is 100 Hz, and the pulse duty cycle is 20%.

6. The LED-pumped narrow pulse width multi-wavelength laser according to claim 3, characterized in that The gain medium of the first LED pump module is Nd:Yttrium aluminum garnet (NAG); both ends are sealed in a cooling water circulation module, and the Nd:Yttrium aluminum garnet crystal is excited by an LED light source to provide a gain with a wavelength of 1064nm.

7. The LED-pumped narrow pulse width multi-wavelength laser according to claim 3, characterized in that The gain medium of the second LED pump module is neodymium-doped lithium yttrium fluoride, both ends of which are sealed in a cooling water circulation module. The neodymium-doped lithium yttrium fluoride crystal is excited by an LED light source to provide gain at wavelengths of 1047 nm and 1053 nm.

8. The LED-pumped narrow pulse width multi-wavelength laser according to claim 1, characterized in that The above-mentioned acousto-optic Q-switched crystal is used to form a Bragg diffraction grating by utilizing the periodic refractive index change generated by ultrasound in the crystal through the acousto-optic effect.

9. The LED-pumped narrow pulse width multi-wavelength laser according to claim 3, characterized in that The output mirror is used as a partial transmission mirror to couple out part of the intracavity light beam and reflect the remaining light beam to continue oscillating in the resonant cavity.

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