200 mJ半导体端面泵浦MOPA激光器研究

采用高功率激光二极管阵列(LDA)端面泵浦Nd:YAG激光棒方式, 结合凸凹非稳腔的设计，获得20 Hz运转条件下小束散角激光输出平均能量约为83 mJ。以该激光为振荡源，同样采用LDA端面泵浦Nd:YAG激光棒的方式进行能量放大，组成LDA端面泵浦振荡-放大(MOPA)激光器，最终获得重频频率20 Hz、平均能量＞200 mJ、发散角＜2.1 mrad、能量波动＜±2.5%的脉冲激光输出。该激光器光光转换效率约为14.6%，体积为175×91×49 mm3，质量＜1 kg，激光经8倍发射天线后发散角＜0.3 mrad。     

基于LD双端面泵浦的Nd:YAG高效率倍频激光器

报道了一种利用激光二极管（LD）双端面泵浦的Nd：YAG激光晶体,Cr⁴⁺：YAG晶体被动调Q,LBO临界相位匹配腔内倍频的高转换效率的绿光激光器。分析了双端面泵浦YAG激光器的热效应,实验中LD双端面泵浦,采用U型平行平面腔结构对Nd：YAG进行传导冷却。当总泵浦光为33.8 W时,得到被动调Q频率10 KHz、功率8.21 W的线偏振基频光输出。6.72 W的绿光输出的倍频效率为86%,输出光束为基模,M²为1.4。实验表明双端面泵浦YAG倍频激光器具有很高的转换效率。     

High-power and high optical conversion efficiency diode-end-pumped laser with multi-segmented Nd:YAG/Nd:YVO_4

A novel flat-flat resonator consisting of two crystals(Nd:YAG + Nd:YVO_4) is established for power scaling in a diode-end-pumped solid-state laser. We systematically compare laser characteristics between multi-segmented(Nd:YAG + Nd:YVO_4) and conventional composite(Nd:YAG + Nd:YAG) crystals to demonstrate the feasibility of spectral line matching for output power scale-up in end-pumped lasers. A maximum continuous-wave output power of 79.2 W is reported at 1064 nm, with M_x~2= 4.82, M_y~2= 5.48, and a pumping power of 136 W in the multi-segmented crystals(Nd:YAG + Nd:YVO_4). Compared to conventional composite crystals(Nd:YAG + Nd:YAG), the optical-optical conversion efficiency of multi-segmented crystals(Nd:YAG + Nd:YVO4) from 808 nm to 1064 nm is enhanced from 30% to 58.8%,while the laser output sensitivity as affected by the diode-laser temperature is reduced from 55% to 9%.     

Investigation on the scattering effect of ceramic Nd:YAG

This paper investigates the scattering effect of domestic 0.5 at{\%} ceramic Nd:YAG. An effective method has been utilized to measure the scattering and absorption coefficients. An end-pumped continuous wave (CW) Nd:YAG ceramic laser was also demonstrated. A maximum output power of 6.7~W at 1064~nm was obtained at an 808-nm pump power of 32.9~W. Conversion efficiency and slope efficiency have been achieved. This indicates that scattering has an important effect on the optical performance of ceramic Nd:YAG.     

Diode end-pumped 1123-nm Nd:YAG laser with 2.6-W output power

We present a compact and high output power diode end-pumped Nd:YAG laser which operates at the wavelength of 1123 nm. Continuous wave (CW) laser output of 2.6 W was achieved at the incident pump power of 15.9 W, indicating an overall optical-optical conversion efficiency of 16.4%, and the slope efficiency was 18%.     

Diode end-pumped high-power Q-switched double Nd:YAG slab laser and its efficient near-field second-harmonic generation

We reported on an all-solid-state double Nd:YAG slab laser. The laser was based on two diode end-pumped Nd:YAG slabs and a stable-unstable hybrid resonator. A cw output of 189 W and an average Q-switched output of 169 W at 10 kHz with an M(2) factor of 1.5 in the slow direction and 1.7 in the fast direction were obtained. We demonstrated efficient near-field frequency doubling by imaging the one-dimensional top-hat near-field to a lithium triborate frequency doubler. We obtained 93 W green light at 10 kHz with a pulse width of 10.7 ns. The efficiency of second-harmonic generation was up to 57%.     

高重复频率1.34μm调Q锁模Nd:YVO_4激光器

报道了基于V:YAG可饱和吸收体的1.34μm被动调Q锁模Nd:YVO4激光器。采用直腔结构,使用透过率为10%的输出镜,在LD端面泵浦的情况下,实现了重复频率高达2.6GHz的1.34μm调Q锁模运转。Nd:YVO4晶体中,Nd3+离子掺杂质量分数为0.2%,V:YAG晶体的初始透过率为83%。在泵浦功率为11 W时,1.34μm调Q锁模激光的最大平均输出功率为308mW,光-光转换效率为2.8%。     

多波长半导体激光阵列端泵Nd:YAG脉冲激光器

研制了无温控多波长激光二极管阵列端面泵浦Nd：YAG电光调Q激光器。采用4 000 W多波长准连续激光二极管阵列作为泵浦源,快轴准直镜与透镜导管作为泵浦耦合系统,端面泵浦φ6 mm×60 mm的Nd：YAG晶体,并采用RTP晶体进行电光调Q实验。在重复频率5 Hz、室温（25℃）时,激光器获得了最大输出能量74.4 mJ、脉宽15 ns的1 064 nm脉冲激光输出,光光转换效率达到11%。在25~55℃的工作温度下,对多波长LDA的光谱特征与激光器的输出特性作了测试,激光器输出能量随着工作温度的上升而先迅速下降再逐步保持稳定,当重复频率分别为5 Hz和10 Hz时,激光器对应的最低输出能量分别为48 mJ与37 mJ。     

High-power simultaneous dual-wavelength emission of an end-pumped Nd:YAG laser using the quasi-three-level and the four-level transition

An efficient continuous-wave (CW) simultaneous dual-wavelength lasing (SDWL) of an LD end-pumped Nd:YAG laser utilizing a quasi-three-level transition at 946 nm and a four-level transition at 1064 nm is reported. A theoretical model has been introduced to determine the threshold conditions for SDWL. The temperature distributions of a Nd:YAG crystal under different pump powers have been analyzed. In the experiments, a CW SDWL output power of 5.12 W at a temperature of 273 K has been achieved with a pump power of 17 W, giving a slope efficiency of 16.36%.     

LDA端面泵浦的Nd：YAG激光器增益开关的动态特性研究

通过速率方程理论对应用增益开关技术的LD端面泵浦Nd:YAG激光器的动态特性进行了较详细的研究.实验以输出波长808nm的LD列阵作端面泵浦源,得到了脉冲宽度小于200ns,峰值功率接近200mW的1.064μm激光输出.实验结果与理论计算结果基本符合.     

热透镜控制激光光束质量技术研究

在端面抽运固体激光器中,就如何改善在高抽运功率时输出激光的光束质量,提出一种激光器的设计方法。在激光器谐振腔中放入多根掺杂浓度不同的激光介质,利用激光介质内部产生的热透镜控制抽运光和基模振荡光的空间分布,并且最大限度地使抽运光的分布区和基模振荡光分布区重叠,实现抽运光与基模振荡光在空间上高度匹配,进而提高抽运光能量的利用效率和振荡光的光束质量。实验表明,在不同抽运功率下,抽运光和基模振荡光在晶体内部的光斑的空间分布可通过热透镜加以控制。在端面抽运功率200 W附近时,实现了抽运光与基模振荡光较高程度匹配,光束质量因子M2由14.7改善为4.1。     

Dual-wavelength Nd:YAG crystal laser at 1074 and 1112 nm

We reported an efficient laser-diode (LD) end-pumped CW dual-wavelength Nd:YAG crystal laser operating at 1074 and 1112 nm simultaneously, for the first time to our knowledge. The maximum output power was 3.15 W with an optical conversion efficiency of 23.6%. Considering the broad absorption of carbonylhemoglobin and hemoglobin located at about 538 and 555 nm, respectively, we proposed that this dual-wavelength laser is an important source for detecting carbon monoxide poisoning by simple frequency doubling.     

Diode end-pumped passively Q-switched Nd:YAG ceramic laser with Cr4+:YAG saturable absorber

We report on a diode end-pumped passively Q-switched Nd:YAG ceramic laser. By using a Cr⁴⁺:YAG single crystal with an 80% initial transmission as the saturable absorber, stable Q-switched pulses with a 126-μJ pulse energy, a 12-ns pulse width, and an 8.4-kHz pulse repetition rate have been obtained. The Q-switching performance of the laser under different saturable absorption strengths and output couplings was experimentally investigated.     

A Compact 532-nm Source by Frequency Doubling of a Diode Stack End-Pumped Nd：YAG Slab Laser

A near-diffraction-limited green source is generated at 1 kHz repetition rate by frequency doubling of a diode stack end-pumped electro-optically Q-switched Nd：YAG slab laser. We obtain 9. 7mJ green light with pulse width of 12.2ns at a repetition rates of i kHz. The pump to green optical conversion efficiency is 12.9%. The energy pulse stability at 532nm is about 0.8%.     

Laser-diode-pumped Nd:YVO<Subscript>4</Subscript>/Nd:YAG MOPA burst-mode laser

We report a high-repetition-rate, high-peak-power laser diode (LD) pumped burst-mode 1064 nm laser from a Nd:YVO₄/Nd:YAG master oscillator power amplifier. 10–100 kHz pulse burst in a duration up to 2 ms is achieved in LD end-pumped Nd:YVO₄ acousto-optically Q-switched laser. After amplification with LD side-pumped Nd:YAG rod amplifiers, the single pulse energy reaches 73 mJ in 10 kHz pulse burst laser with a peak power of 7.8 MW.     

Analysis of a laser-diode end-pumped passively Q-switched Nd:GdVO4 laser with V3+:YAG saturable absorber

By considering both the transversal and longitudinal Gaussian spatial distribution of the intracavity photon density, a couple of rate equations describing a laser-diode end-pumped passively Q-switched Nd:GdVO₄ laser with V³⁺:YAG saturable absorber have been proposed. Solving these space-dependent rate equations numerically, we obtain the dependences of pulse width, pulse repetition rate, single-pulse energy and peak power on pump power. In the experiment, a laser-diode end-pumped Nd:GdVO₄ laser passively Q-switched by a V³⁺:YAG saturable absorber has been realized, and the experimental results are consistent with the theoretical calculations.     

End-pumped Nd:YAG zigzag slab laser with weak pump absorption

A diode-pumped Nd：YAG oscillator laser with an end-pumped zigzag slab architecture and weak pump absorption is developed. An output power of 253 W with a slope efficiency of 50.2% and an optical-optical conversion efficiency of 39.6% is achieved from the resonator, which emits the maximum power of 290 W with 840-W pump power. An optimum laser diode （LD） array coolant temperature is chosen in an attempt to realize the weak but uniform pump absorption. of zigzag slab resonator depends sensitively on the Furthermore, we have confirmed that the performance incident angle of the beam at the slab end face.     

Nd:YVO4自受激拉曼激光器调Q锁模特性

利用Nd:YVO4激光晶体的自受激拉曼效应,结合Cr:YAG被动锁模技术和倍频技术,实现了结构紧凑的1176 nm和588 nm黄光锁模激光输出。激光器为LD端面泵浦,三镜折叠腔结构,并且采用了透过率为10%的输出镜。Nd:YVO4晶体长度为10 mm,Nd3+离子掺杂质量分数为0.2%,Cr:YAG晶体的初始透过率为67%。10 W激光泵浦时,1176 nm激光平均输出功率为123 mW,调Q包络宽度为6 ns,调Q包络内的锁模脉冲重复频率高达1 GHz。588.2 nm 黄光的平均输出功率为8 mW。     

LD端面泵浦Cr4:YAG被动调Q激光器输出特性研究

对激光二极管端面泵浦Cr⁴⁺:YAG被动调QNd:YAG激光器输出特性进行了实验研究.实验研究发现,激光器输出功率及脉冲重复频率随谐振腔长度增大而增大.为解释这一实验现象,测量了泵浦光斑在激光晶体内尺寸,同时计算了激光晶体及Cr⁴⁺:YAG晶体内的基模激光光斑半径随谐振腔长度变化.分析结果表明:激光晶体内泵浦光斑尺寸远小于激光晶体内基模光斑半径,腔模间交叠效率较低;当腔长增加时,激光晶体内的基模激光光斑减小,腔模间交叠效率增加,从而导致输出功率及脉冲重复频率随腔长增加而增加;另外,Cr⁴⁺:YAG晶体内光斑半径也随谐振腔长度减小,引起Cr⁴⁺:YAG晶体漂白时间缩短,导致脉冲重复频率随腔长增加而增加.     

Compact, efficient diode-end-pumped Nd:GdVO4 slab continuous-wave 912-nm laser

A fiber-coupled laser-diode (LD) end-pumped Nd:GdVO₄ slab continuous-wave (CW) 912-nm laser and an LD bar end-pumped Nd:GdVO₄ slab CW 912-nm laser are both demonstrated in this paper. Using the fiber-coupled LD of end-pumped type, a highest CW 912-nm laser output power of 10.17 W is obtained with a high optical-to-optical conversion efficiency of 24.6% and a slope efficiency of 34.5%. The measured M² factors of beam quality in x and y directions are 5.3 and 5.1, respectively. Besides, an LD bar of end-pumped type is used to realize CW 912-nm laser output, which has the advantages of compactness and low cost. When the pump power is 38.8 W, the output power is 8.87 W and the measured M² factors of beam quality in x and y directions are 16 and 1.31, respectively. In order to improve the beam quality of the 912-nm laser at x direction, a new quasi-concentric laser resonator will be designed, and an LD bar end-pumped Nd:GdVO₄ slab high-power CW 912-nm TEM₀₀ laser will be realized in the future.