脉冲单频Nd:YVO4激光器及其倍频输出特性研究

为了研制激光干涉成像所需的主振荡功率放大(MOPA)结构脉冲单频激光器,本文完成MOPA激光器的种子源即声光调Q脉冲单频1 064 nm激光器的特性研究,同时完成种子源腔外倍频绿光特性研究。脉冲单频激光器采用声光调Q模块实现脉宽约20 ns的1 064 nm脉冲激光输出,采用环形腔设计并采用一组不同厚度的标准具实现单纵模运转。实验研究基频1 064nm和倍频532 nm激光脉冲的线宽,得出在全脉宽范围内都具有较高时间相干性的结论。实验分别获得脉宽约28 ns峰值功率约6.5 kW的1 064 nm脉冲单频激光和脉宽约20 ns、峰值功率约0.5 kW的532 nm脉冲单频激光,腔外倍频效率为5.6%。实验同时也验证了腔外倍频的激光脉宽压缩效应。     

光纤激光泵浦MgO:PPLN高功率中波红外光参量振荡器

为实现高效率、高功率中波红外激光输出,研制基于MgO:PPLN晶体的中波红外光参量振荡器（OPO）,泵浦源为基于主振荡功率放大（MOPA）结构的线偏振掺Yb光纤激光器（YDFL）。实验结果表明:YDFL可实现最高79.1 W的1064.1 nm脉冲线偏振激光输出;在YDFL泵浦下,通过优化输出镜曲率半径和泵浦光束腰直径,该OPO实现最高9.15 W的3.754 μm脉冲激光输出,光光转换效率为11.57%,重复频率为300 kHz,脉冲宽度约为110 ns。     

Diode-pumped Nd:YLF slab master oscillator power amplifier laser system with 655 m J output at 50 Hz repetition rate

A laser-diode-pumped high-pulse-energy Nd:Li YF4 master oscillator power amplifier 1053 nm laser system is demonstrated. We design a home-made pump module to homogenize the pump intensity through the ray tracing method. To increase the extraction efficiency, the pre-amplifier adopts a double-pass amplification structure. At a repetition rate of 50 Hz, 655 m J pulse energy and 12.9 ns pulse width of 1053 nm laser is obtained from the master oscillator power amplifier system. The corresponding peak power is 51 MW. The optical-to-optical efficiency of the system is about 9.7%.     

220 μJ monolithic single-frequency Q-switched fiber laser at 2 μm by using highly Tm-doped germanate fibers

We report a unique all fiber-based single-frequency Q-switched laser in a monolithic master oscillator power amplifier configuration at ~1920 nm by using highly Tm-doped germanate fibers for the first time. The actively Q-switched fiber laser seed was achieved by using a piezo to press the fiber in the fiber Bragg grating cavity and modulate the fiber birefringence, enabling Q-switching with pulse width and repetition rate tunability. A single-mode polarization maintaining large core 25 μm highly Tm-doped germanate fiber was used in the power amplifier stage. For 80 ns pulses with 20 kHz repetition rate, we achieved 220 μJ pulse energy, which corresponds to a peak power of 2.75 kW with transform-limited linewidth.     

高功率全固态绿光激光技术研究进展

 报道了高功率全固态腔内和腔外倍频两种绿光激光器研究进展。腔内倍频绿光激光器采用L型腔双棒串接结构,在重复频率10 kHz时,用三硼酸锂晶体倍频获得绿光功率186 W,光-光效率达15.8%。腔外倍频绿光激光器采用主振荡和功率放大器,在重复频率400 Hz时,获得基频激光单脉冲能量1.2 J,采用Ⅱ类相位匹配KTP晶体腔外倍频,获得525 mJ的绿光输出,倍频效率为43.7%。采用偏振合成技术获得了单脉冲能量大于1 J的绿光输出。在该激光放大器实验装置上,进行了双模块热效应补偿技术和受激布里渊散射相位共轭技术实验研究,改善了激光光束质量。     

Generation of high energy and good beam quality pulses with a master oscillator power amplifier

A high efficiency and high peak power laser system with short-pulse and good beam quality has been demonstrated by using a master oscillator power amplifier with two-pass amplification configuration. The master oscillator, end-pumped with a fiber-coupled laser diode array, provides low power but excellent beam quality pulses, and the amplifier boosts the pulse energy by orders without significant beam quality degradation. Short pulses of 8.5 ns with energy up to 130 mJ and approximately diffraction limited beam quality have been demonstrated.     

High-energy single longitudinal mode 1 ns all-solid-state 266 nm lasers

A single longitudinal mode (SLM) short pulse high energy all-solid-state ultraviolet laser is demonstrated in this paper. Through the use of a master oscillator power amplifier (MOPA) architecture, we have been able to provide high-energy outputs with the combination of short pulses, good beam quality and SLM typically produced by a 1064 nm Nd:YAG laser. The passively Q-switched SLM Nd:YAG laser in a twisted-mode cavity is operated as the seed source. After the seed is amplified by a double-pass pre-amplifier and a single-pass main-amplifier, the 100 μJ, 1064 nm, ∼1 ns seeding pulse was amplified up to 400 mJ energy in the total pulse train. Using a KTP crystal for second-harmonic generation and a CLBO for fourth-harmonic generation, we successfully obtained a short pulse, high energy ultraviolet laser of 266 nm, with the output energy of 108 mJ, pulse width 1 ns and M²<5. PACS 42.65.Ky; 42.72.Bj; 42.60.Da     

High-efficiency nanosecond optical parametric oscillator with the stable ring configuration

High stability nanosecond OPO operation at 1.57 μm was realized based on the type II non-critically phase-matched (NCPM) KTP crystal by utilizing a single frequency Nd:YAG master oscillator power amplifier (MOPA) laser as pump source. Energy conversion efficiency of 18.1% was demonstrated with single-pass ring cavity which was approximately two times more than that of critical ring cavity. The highest slope efficiency of 37.76% and maximum signal pulse energy of 3.1 mJ were attained with the output reflectivity of R = 50% at the pulse repetition frequency of 100 Hz. Experimental results reveal that the nanosecond OPO with ring stable configuration is a promising design to meet the need of IPDA’s transmitter.     

Efficient electro-optic Q-switched eye-safe optical parametric oscillator based on KTiAsO4

An efficient high-energy, high-peak-power eye-safe optical parametric oscillator (OPO) at 1536 nm based on a noncritically phase-matched KTA crystal pumped by a quasi-cw diode side-pumped electro-optic Q-switched Nd:YAG laser is presented. The maximum output energy is 74.9 mJ, corresponding to an optical-to-optical conversion efficiency of 12.14% and an electrical-to-optical conversion efficiency of 4.73%. The pulse width (FWHM) is about 3.5 ns with a peak power of 21.4 MW. Moreover, the maximum electrical-to-optical conversion efficiency and optical-to-optical conversion efficiency are up to 4.94% and 15.6%, respectively.     

高强度泵浦碱金属蒸气激光器的光参量振荡器

以电光调Q的Nd:YAG激光器为泵浦源,以磷酸氧钛钾（KTP）为非线性晶体,搭建了调谐范围为750~800 nm的光参量振荡器。信号光在中心波长780.2 nm处获得单脉冲能量113 mJ、脉宽15.43 ns、光斑直径5.5 mm的输出。用光栅单色仪测量信号光光谱宽度（FWHM）为0.38 nm。信号光通过120 ℃的铷蒸气池,观察到清晰的荧光轨迹。证明信号光能有效泵浦铷蒸气,可为铷激光器提供峰值功率7 MW的高强度脉冲泵浦源,进而研究铷激光器在高强度泵浦条件下的动力学过程和基础物理机制。     

Zig-Zag板条泵浦的2.12μm激光器

 为了实现窄脉宽、高峰值功率2.12 μm激光的稳定输出,设计了基于侧面泵浦Zig-Zag 板条产生1.06 μm基频光,进而泵浦KTP晶体通过II类相位匹配产生2.12 μm激光的光参量振荡实验。对外腔及内腔进行了实验研究,分别获得了1.53%和2.86%的电光转换效率。在20 Hz频率下内腔2.12 μm输出能量达到70 mJ以上,脉宽7 ns~9 ns。其中内腔实验中能量输出稳定度接近8%。     

Narrowband, tunable, frequency-doubled, erbium-doped fiber-amplifed transmitter

We report on the development of a fiber-based laser transmitter designed for active remote sensing spectroscopy. The transmitter uses a master oscillator power amplifier (MOPA) configuration with a distributed feedback diode-laser master oscillator and an erbium-doped fiber amplifier. The output from the MOPA is frequency-doubled with a periodically poled potassium titanium oxide phosphate crystal. With 35 W of single-frequency peak optical pump power, 8 W of frequency-doubled peak power was achieved. The utility of this single-frequency, wavelength tunable, power scalable laser was then demonstrated in a spectroscopic measurement of diatomic oxygen A band.     

Conductively-cooled,high-energy,single-frequency diode pumped slab laser for space applications

A laser-diode-pumped high efficiency, high pulse energy and single-frequency oscillator and amplifier for potential space environment applications have been developed and demonstrated using conductively-cooled heat removal. A diode-pumped injection seeded single-frequency oscillator was achieved by using the resonance-detection technique in Q-Switching operation, and Nd: YAG zigzag slabs based on “pump on bounce” are used in power amplifier stage for high-efficiency pulse energy extraction. Output pulse energy of 800 mJ with 11 ns pulse duration is obtained at a repetition rate of 100 Hz, with a near 3× diffraction-limit beam and an optical-to-optical efficiency of 18%. The experimental result shows that the laser has compact structure, high efficiency, reliability, conductive cooling and can be used for space environments.     

Intracavity optical parametric oscillator based on GTR-KTP pumped by diode-side-pumped acousto-optically Q-switched Nd:YAG laser

With a non-critically phase-matched high gray-trace resistance KTP (GTR-KTP) crystal, a high-power intracavity optical parametric oscillator (IOPO) emitting at the wavelength of 1.5 μm and pumped by a diode-side-pumped acousto-optically Q-switched Nd:YAG laser is experimentally demonstrated. At the frequency repetition rate of 6 kHz, the maximum average power of 6.36 W at signal wavelength 1570 nm with a pulse width of 9.94 ns is obtained from IOPO based on GTR-KTP, corresponding to a peak power of 107 kW and a single-pulse energy of 1.06 mJ, respectively. We have compared the GTR-KTP IOPO with common KTP IOPO using the same scheme. At the same cavity design, frequency repetition rate and pump condition, only 5.42 W average output power with pulse width 13.82 ns is obtained from IOPO based on common KTP. Besides the higher output power, the output stability of GTR-KTP IOPO is much better than that of common KTP OPO. The output instability of GTR-KTP IOPO is 0.83% versus 6.7% of the common KTP IOPO.     

An efficient intracavity-pumped KTP optical parametric oscillator at 1572 nm

We demonstrate an efficient and eye-safe wavelength intracavity optical parametric oscillator (OPO),based on a KTP crystal inside a Q-switched Nd:YVO4 laser end pumped by a fiber-coupled diode laser. Inthe acousto-optic Q-switched operation with the pulse repetition rate of 10 kHz, a 1572-nm eye-safe laser with the average power of 237 mW at the incident pump power of 5.64 W is obtained. Under the pulse repetition rate of 5 kHz, the signal light with pulse width of 2 ns and peak power of 18.5 kW is achieved.The conversion efficiency of the average power is 4.2% from pump diode to OPO signal output and thesignal pulse duration is about 13 times shorter than that of the depleted pump light.     

High-repetition-rate eye-safe intracavity KTA OPO driven by a diode-end-pumped Q-switched Nd:YVO4 laser

An eye-safe, high-repetition-rate, single-resonant nanosecond intracavity optical parametric oscillator (IOPO), based on a non-critically phase-matched KTA crystal driven by a diode-end-pumped acousto-optically Q-switchedNd:YVO4 laser, was demonstrated for the first time to our knowledge. With an absorbed pump power of 11.3 W, 1.1 W average power and 2.5 ns pulse width at the signal (1534 nm) wavelength for 30-kHz repetition rate are synchronously achieved with the 25 mm long KTA crystal. The corresponding peak power and single pulse energy are estimated to be up to 14.7 kW and 36.7 μJ. The conversion efficiency from diode laser power to OPO signal output power was 9.8% and the corresponding slope efficiency was 15.4%. PACS 42.60.Gd; 42.65.Yj; 42.55.Xi     

1.57μm被动调Q光学参量振荡器

在半导体泵浦被动调QNd∶GdVO4/Cr4+∶YAG激光腔内,利用KTP晶体实现了高重复频率的内腔OPO的稳定运转。OPO其信号光转换效率为7%,斜效率为10.3%。当泵浦功率7.3W时,可获得平均功率为0.48W,重频15kHz,脉宽6ns,峰值功率达13KW的1570nm激光输出。     

高能量高转换效率355 nm紫外激光器

为了得到一种三倍频效率高达60%的355 nm脉冲激光器,采用曲率半径分别为2 m的凹凸高斯镜和9 m的平凹全反镜组合作为谐振腔,加以电光调Q,得到1 064 nm高光束质量激光输出,再将其进行行波放大,获得重复频率10 Hz、脉宽7.3 ns、单脉冲能量1.01 J的1 064 nm基频光输出。利用Ⅰ类相位匹配LBO晶体进行二倍频、Ⅱ类相位匹配LBO晶体进行三倍频以得到波长为355 nm的紫外光输出。通过二倍频和三倍频输出特性和非线性晶体参数的分析和实验调试,最终获得了单脉冲能量为608 mJ、脉宽为5.7 ns、线宽为2 nm的紫外激光输出。通过优化二倍频的转换效率,可使1 064 nm基频光到三倍频得到的355 nm紫外光的转换效率达60%。     

微型化LD泵浦Er~(3+),Yb~(3+)共掺磷酸盐玻璃被动调Q激光器

报道了一种主要应用于激光测距的微型化激光二极管泵浦Er3+/Yb3+共掺磷酸盐玻璃被动调Q激光器。采用中心波长940nm的二极管作为泵浦源,Er3+/Yb3+共掺磷酸盐玻璃作为增益介质,Co2+:MgAl2O4作为被动调Q晶体,通过优化增益介质和被动调Q晶体参数,获得了最佳的增益介质长度和被动调Q晶体初始透过率。当泵浦能量14mJ,重复频率10Hz,泵浦脉宽5ms时,获得了单脉冲能量480μJ,脉宽5ns,峰值功率大于20kW的激光输出,激光光束质量因子为1.2。     

瓦级激光二极管端面抽运351nm紫外激光器

研制了输出功率达瓦级的351 nm准连续紫外激光器。激光器采用激光二极管(LD)端面抽运Nd∶YLF晶体和声光调Q技术,实现了1 053 nm准连续基波振荡。在结构简单的V型腔中,两块Li B3O5(LBO)晶体对基频光进行二倍频和三倍频,获得了高功率351 nm准连续紫外激光输出。在LD抽运功率为14 W、声光调Q激光器的调制频率为1 k Hz的工作条件下,得到351 nm紫外激光平均输出功率为1.12 W、脉冲宽度为34 ns、单脉冲能量为1.12 m J、峰值功率达32.94 k W。LD抽运光到351 nm紫外激光的光-光转换效率达到8%,电光效率为3.4%,光束质量良好。