Simultaneous Q-switching and Frequency-doubling by a Single KTP Crystal in a Diode-pumped Nd:YVO4 Laser

The interrelation between the phase matching condition for second harmonic generation (SHG) and the electro-optic Q-switching in KTP was numerically analyzed. A diode-pumped Q-switched Nd: YVO4/KTP green laser was reported, where the KTP crystal was simultaneously used as both an electrooptic Q-switcher and a frequency-doubling crystal in type Ⅱ phase matching.Compared with the conventional frequency-doubling and Q-switching configuration, low loss and high efficiency characteristics were realized by using a single KTP crystal. The Q-switched green laser pulse with a peak power of 762 W and a pulse width of 12 ns was obtained with 1 W pump power.     

678 nm RTP electro-optical Q-switched ceramic laser

The RTP electro-optical Q-switched ceramic laser at the wavelength of 678 nm with narrow pulse width is studied. We used the laser diode arrays side-pumped Nd:YAG ceramic crystal with 1.1 at% Nd doping and dimensions of Φ3 mm × 50 mm, designed folding cavity parameters, and discussed the variation of the beam radius in the ceramic crystal and frequency doubling crystal with the thermal focal length of ceramic crystal or KTP crystal. By using double RTP crystals as electro-optic Q-switch and KTP crystal type II phase matching for intracavity frequency-doubling, a narrow pulse width electro-optical Q-switched Nd:YAG ceramic laser was obtained. The output energy of 0.9 mJ and the pulse width of 41.6 ns at 678 nm are obtained at the repetition rate of 1000 Hz and pumped power of 144 W. The results formed the basis for the further development of the high power and high efficiency ceramic red laser.     

Diode end-pumped Q-switched high-power intracavity frequency-doubled Nd:GdVO4/KTP green laser

A diode-laser-array end-pumped acousto-optically Q-switched intracavity frequency-doubled Nd:GdVO₄/KTP green laser, formed with a three-mirror folded resonator, has been demonstrated. With 15 W of pump power incident upon the Nd:GdVO₄ crystal, a maximum average green output power of 3.75 W was obtained at 50 kHz of pulse repetition frequency, giving an optical conversion efficiency of 25%, whereas the effective intracavity frequency-doubling efficiency was determined to be 72%. At the incident pump power of 12.8 W, the shortest laser pulse was achieved at a pulse repetition rate of 10 kHz, the resulting pulse width, single pulse energy, and peak power were measured to be 35 ns, 108 μJ, and 3.1 kW, respectively. Received: 18 May 2000 / Published online: 20 September 2000     

LD泵浦Nd3+∶GdVO4/Cr4+∶YAG固体激光器

通过合理设计，精密调控各元件和温控电流，得到了平均功率为70mW，脉冲宽度为22ns，重复频率为14 kHz，峰值功率高达230 W的Nd³⁺∶GdVO₄/Cr⁴⁺YAG绿光脉冲激光器.腔外采用望远镜系统聚焦，经KTP晶体倍频后，得到了平均功率为28.8 mW，脉冲宽度为19 ns，重复频率为14 kHz，峰值功率高达108 W的绿光激光输出，转换效率高达.指出了小光斑对倍频晶体带来的影响.     

Diode-pumped Q-switched Nd:GdVO4/KTP green laser formed with a flat–flat resonator

A diode-pumped acousto-optically Q-switched intracavity frequency-doubled Nd:GdVO₄/KTP green laser formed with a flat–flat resonator was demonstrated. 3.05 W of average green output power at pulse repetition frequency (PRF) of 40 kHz was obtained with an optical conversion efficiency of 18.4%, the effective intracavity frequency-doubling efficiency was 57%. At the incident pump power of 15 W, the shortest laser pulse occurred at PRF of 25 kHz with FWHM width of 14 ns, yielding the highest peak power of 7.44 kW; while the largest pulse energy of 0.14 mJ was achieved at PRF of 15 kHz.     

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。     

Diode-end-pumped solid-state ultraviolet laser based on intracavity third-harmonic generation of 1.06 μm in YCa4O(BO3)3 crystal

Intracavity type-I sum-frequency mixing of 1.06 μm and 532 nm with a (θ,)=(106°,77.2°)-cut YCOB crystal was performed in a compact laser-diode-pumped solid-state laser. Three type-II phase-matching KTP crystals with different length were used to generate 532 nm light by frequency-doubling of 1.06 μm. The 355 nm output power was measured with the three KTP crystals for Q-switched and continuous-wave (CW) operation, respectively. The maximum ultraviolet output power of 1305 μW was obtained with a 15 mm KTP crystal for CW operation, while the maximum ultraviolet average output power of 124 mW was obtained with a 10 mm KTP crystal for Q-switched operation.     

Efficient 532 nm laser using high gray-tracking resistance KTP crystal

A LD end-pumped acoustic-optic Q-switched intracavity frequency-doubled Nd:YVO₄ laser was demonstrated. It uses a high gray-tracking resistance KTP crystal as nonlinear optical crystal. The output characteristics of 532 nm green laser using different doping concentrations and cavity configurations were investigated. With the pump power of 27.5 W, a maximum average power of 13 W at 532 nm was achieved at a pulse repetition rate of 80 kHz, corresponding to the optical-to-optical efficiency of 47.3%. The pulse width is 30 ns and single pulse energy is up to 162.5 μJ. This work is a significant exploration for using a high gray-tracking resistance KTP crystal to generate highly efficient frequency-doubled green laser.     

Frequency doubling of narrow-linewidth pulsed fiber laser

A pulsed master oscillator power amplifier system is constructed using a double-cladding polarized Ybdoped fiber and an all-fiber Q-switched narrow-linewidth pulsed laser used as seed laser.This system has a high repetition rate and provides a nanosecond pulsed laser with a narrow linewidth and linear polarization.Moreover,it generates amplified radiation with up to 14 W of average power,narrow linewidth(full-width at half-maximum is smaller than 0.12 nm),linear polarization at 1 080-nm wavelength,repetition rate of 51 kHz,and pulse duration of approximately 50 ns.Based on this pulsed amplified radiation,3.5 W of green laser,with an optical-to-optical efficiency of 27.3%,is obtained via single-pass frequency doubling using a noncritical phase matching KTP crystal.     

670nm电光调Q陶瓷激光器

为了进一步研究Nd∶YAG陶瓷激光器的红光波段,研制了一台重复频率为1 000 Hz的670 nm电光调Q Nd∶YAG陶瓷激光器.采用三个激光二极管列阵侧面抽运掺杂浓度为1.1at%、尺寸为Φ3×50 mm2的Nd∶YAG陶瓷晶体,根据实验测量的陶瓷晶体热透镜焦距,优化设计了折叠腔的各个参量,并对陶瓷晶体及倍频晶体热...     

The study of green laser performances by using composite crystals of different initial transmissions

This paper reported a passively Q-switched green laser of LD pumped linear cavity structure by using Nd:YAG/Cr⁴⁺:YAG composite crystal and the type II phase matching KTP crystal. The dependence of average output power, pulse width and pulse repetition rate on pump power at different initial transmissions of Cr⁴⁺:YAG were measured and analyzed. With Cr⁴⁺:YAG of 80% initial transmission, under pump power of 13.97 W, the output average power is up to 681 mW, with pulse width of 200 ns and pulse repetition rate of 9.1 kHz. The laser operates in a fundamental mode.     

Theoretical and experimental study of a diode-pumped doubly Q-switched intracavity-frequency-doubling Nd:LuVO4/KTP green laser with acoustic-optic (AO) modulator and GaAs saturable absorber

By considering the Gaussian transversal and longitudinal distributions of the intracavity photon density as well as the walk-off effect of KTP crystal, the coupled rate equations of the doubly Q-switched intracavity-frequency-doubling Nd:LuVO₄/KTP green laser with acoustic-optic (AO) modulator and GaAs saturable absorber are given. These equations are solved numerically and the doubly Q-switched green laser characteristics, such as the pulse width and the pulse symmetry, have been obtained. In the experiment, a diode-pumped doubly Q-switched intracavity-frequency-doubling Nd:LuVO₄/KTP green laser with AO and GaAs is presented. This doubly Q-switched green laser can generate the almost absolutely symmetric pulse profile with the shorter pulse width and the higher power than the singly Q-switched green laser. The experimental results are in agreement with the theoretically numerical calculations.     

高功率二极管泵浦腔内倍频激光器

 成功研制了一台高功率二极管泵浦声光Q开关腔内倍频Nd:YAG激光器。当泵浦功率约为350W时，采用透过率为30%的输出耦合镜，调Q激光输出功率32.5W，脉宽约200ns，重复频率7kHz；采用Ⅱ类匹配KTP晶体腔内倍频，获得了32.5W的绿光输出，脉宽约120ns。输出光束平滑，远场为类高斯分布，测得的光束质量因子为3.6。     

50.2W high stability and high compact all-solid-state green laser with extra-cavity frequency-doubling at 500 Hz

A 50.2W high pulse energy green laser system at 532 nm was demonstrated by extra-cavity second-harmonic generation (SHG). The fundamental laser was based on laser diode (LD) side-pumped MOPA Q-switched technology, producing 79W of average power at the repetition rate of 500 Hz, while the pulse width was 6 ns. Type-II angle phasematched KTiOPO₄ (KTP) crystal was used as the nonlinear crystal. The 50.2W average power of 532 nm laser was obtained with the divergence angle less than 0.6 mrad and the corresponding peak power of 16.7MW. The optical frequency conversion efficiency from fundamental to green laser was up to 63.5%. The measured output power fluctuation was less than 0.38% in one hour operation.     

低温GaAs被动调Q锁模Nd:Gd0.42 Y0.58VO4 混晶激光器特性研究

采用低温生长GaAs晶体作为被动饱和吸收体兼输出镜,实现了Nd:Gd0.42Y0.58VO4混晶激光器的调Q锁模运转.研究了Nd:Gd0.42Y0.588VO4激光器的基频运转特性.在输出镜透射率T=10%、腔长L=40 mm的情况下,当抽运功率为8.6 W时,获得激光输出功率3.78 W,光-光转换效率为43.9%.并测量了Nd:Gd0.42Y0.58VO4混晶被动调Q激光器的输出特性.实验结果表明激光器调Q运转阈值为2 W,当抽运功率为3.7 W时,激光器出现调Q锁模行为;当抽运功率为8.6 W时,激光器调Q锁模深度达70%以上,对应的脉冲包络重复频率为670 kHz,半峰全宽为180 ns,平均输出功率为1.35 W,光-光转换效率为15.7%.     

101 W of average green beam from diode-side-pumped Nd:YAG/LBO-based system in a relay imaged cavity

A 52-W green laser at 532 nm by extra-cavity second-harmonic generation in a coupled-cavity configuration is demonstrated. The fundamental laser is a diode-side-pumped acousto-optic (AO) Q-switched Nd:YAG rod laser producing 84 W of average power at 1064 nm at 8 kHz repetition rate. Type-II phase-matched polished KTP crystal is used as the nonlinear crystal for second-harmonic generation. The individual green pulse width is 50 ns and the fundamental to second harmonic conversion efficiency is 61.8%.     

Efficient and high-power green beam generation by frequency doubling of acousto-optic Q-switched diode-side pumped Nd:YAG rod laser in a coupled cavity

A 52-W green laser at 532 nm by extra-cavity second-harmonic generation in a coupled-cavity configuration is demonstrated. The fundamental laser is a diode-side-pumped acousto-optic (AO) Q-switched Nd:YAG rod laser producing 84 W of average power at 1064 nm at 8 kHz repetition rate. Type-II phase-matched polished KTP crystal is used as the nonlinear crystal for second-harmonic generation. The individual green pulse width is 50 ns and the fundamental to second harmonic conversion efficiency is 61.8%.     

LD泵浦Nd：YAG/Cr：YAG腔外频率变换高功率紫外激光器

用KTP晶体对激光二极管端面泵浦的Nd:YAG晶体;Cr:YAG被动调Q产生的1064nm脉冲激光器进行腔外倍频,用BBO晶体四倍频产生266 nm紫外激光.用15 W的LD阵列;当LD泵浦功率为12 W的情况下;红外(1064 μm)调Q平均输出功率为2.2 W;脉冲序列周期为40 μs;脉宽为18ns;峰值功率高达4.9kW.采用KTP腔外二倍频;532nm的绿光输出平均功率为850mW;用BBO腔外四倍频;266nm的紫外光输出平均功率高达215mW，绿光-紫外光光转换效率为25.2%, 红外到紫外总的转换效率为9.8%.     

High-Power passively Q-switched 532 nm green laser by using Nd:YAG/Cr4+:YAG composite crystal

This paper reported a passively Q-switched 532 nm green laser of LD pumped V cavity structure by using Nd:YAG/Cr⁴⁺:YAG composite crystal and the type II phase matching KTP crystal. Under 19.4 W pump power, the average power of the laser pulse up to 1.83 W, with the pulse width of 93.2 ns and repetition frequency of 9.1 kHz.     

Diode-pumped cw and Q-switched Nd:GdVO4 laser operating at 1.34 μm

A diode-pumped 1.34 m Nd:GdVO₄ laser operating in cw and active Q-switching modes has been demonstrated. 4.15 W of cw output power was obtained at the highest attainable pump power of 12.3 W, resulting in an optical conversion efficiency of 33.7%, the slope efficiency was determined to be 37.6%. In Q-switching operation, a maximum average output power of 2.7 W was generated at pulse repetition frequency (PRF) of 50 kHz, with an optical conversion efficiency of 22% and a slope efficiency of 29.2%. The laser pulses with shortest duration, highest energy and peak power were achieved at PRF of 10 kHz, the parameters being 15 ns, 160 J, and 10.7 kW, respectively. By intracavity frequency-doubling with a type II phased-matched KTP crystal, 0.62 W average power at 0.67 m was produced at a PRF of 15 kHz, the resulting pulse energy, peak power, and pulse width being 41.3 J, 2.2 kW, and 19 ns, respectively. A group of analytical formulae, based on rate equations, are presented to evaluate the operational parameters of an actively Q-switched laser. Calculated results were found to be in close consistency with the experimental data.