Efficient subnanosecond diode-pumped passively Q-switched Nd:YVO4 self-stimulated Raman laser

Generation of efficient subnanosecond self-stimulated Raman pulses by a diode-pumped passively Q-switched Nd:YVO4/Cr4+:YAG laser is demonstrated. Experimental results reveal that self-frequency Raman conversion can be achieved with a c-cut Nd:YVO4 crystal in a nearly hemispherical cavity. At 2.0 W of incident pump power, the self-stimulated Raman laser produces stable 710-ps pulses at a Stokes wavelength of 1178.6 nm with 7.2 microJ of pulse energy at a 17-kHz repetition rate.     

Second-Stokes YVO4/Nd:YVO4/YVO4 self-frequency Raman laser

We demonstrated an efficient second-Stokes Raman laser emission at 1313 nm based on self-frequency stimulated Raman scattering from a diode-end-pumped actively Q-switched YVO(4)/Nd:YVO(4)/YVO(4) laser at 1064 nm for the first time, to the authors' knowledge. A double-end diffusion-bonded Nd:YVO(4) composite crystal was adopted for sufficiently improving the thermal lensing effect in the course of self-frequency stimulated Raman scattering operation. With an incident pump power of 14.6 W and a pulse repetition (PRR) of 40 kHz, a maximum average output power of 2.34 W was obtained, corresponding to an optical-to-optical conversion efficiency of 16%. Pulse width and peak power were 1.2 ns and 49 kW, respectively.     

新型激光晶体Nd：GdVO_4

报导了新型激光晶体Nd:GdVO4的结构及生长;研究了其光谱特性,得出在808 nm处具有较强的吸收峰,且三个主发射峰波长分别为912.6 nm、1 063.1 nm、1 341.3 nm;讨论了其热导率,认为具有很高的热导率可能是因为掺入Nd3 后晶格畸变并不大引起的;通过与Nd:YVO4和Nd:YAG进行性能比较,证明该晶体是LD泵浦高功率激光器的理想工作物质.     

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%.     

Study on optical characteristics of Nd:YVO4/YVO4 composite crystal laser

Thermal effect in crystals is the main obstacle blocking diode-pumped solid state laser to get high and stable output power. Diffusion bonding crystal has been demonstrated to be an effective method to relieve the thermal lensing theoretically based on the numerical heat analysis to the end-pumped anisotropic laser crystal. The temperature distributions in Nd:YVO4/YVO4 composite crystal and conventional crystal were analyzed and compared. The end-pumped Nd:YVO4/YVO4 composite crystal laser was designed and set up with z-cavity. The maximum output powers of 9.87 W at 1064 nm and 6.14 W at 532 nm were obtained at the incident pump power of 16.5 W. The highest optical-optical conversion efficiencies were up to 59.8% at 1064 nm and 37.2% at 532 nm respectively.     

Generation of all-solid-state, high-power continuous-wave 213-nm light based on sum-frequency mixing in CsLiB6O10

Achievement of more than 100 mW of pure continuous-wave deep-ultraviolet radiation at 213 nm has been demonstrated in an efficient all-solid-state laser system that uses two Brewster-cut CsLiB6O10 (CLBO) crystals. The first crystal is used for 266-nm generation by external resonant doubling of 532-nm radiation from a frequency-doubled Nd:YVO4 laser. Subsequent sum-frequency mixing is performed in a second CLBO crystal placed in a diode-pumped Nd:YAG laser cavity to mix the single-pass 266-nm output with circulating 1064-nm light.     

LBO Ⅰ类临界相位匹配内腔和频555 nm激光器

报道了全固态连续波555 nm激光器.555 nm激光是分别由Nd:YAG和Nd:YVO4晶体的946 nm和1342 nm谱线非线性和频产生,两条谱线在各自晶体对应能级跃迁分别为4F3/2-4Ⅰ9/2和4F3/2-4Ⅰ13/2.实验中采用复合折叠腔结构,利用LBOI类临界相位进行腔内和频,当注入Nd:YAG和Nd:YVO4晶体的泵浦功率分别为20 W和10 W时,获得1.06 W的TEM00连续波555 nm激光输出.4小时功率稳定度优于±3.3%.实验结果表明采用两种激光晶体进行腔内和频是获得激光的高效方法,并可以应用到其它两种激光晶体进行腔内非线性和频,获得更多不同波长激光输出.     

Continuous-wave, all-solid-state, intracavity Raman laser

Continuous-wave operation of a diode-pumped solid-state Raman laser at 1176 nm is reported. The intracavity Raman laser, based on a Nd:YAG laser crystal and a KGd(WO4)2 Raman crystal, reached threshold for 4 W of diode input power and gave up to 800 mW of output power at an overall conversion efficiency of 4%.     

掺Nd锆石类激光晶体的Raman光谱研究

测量了Nd∶YVO4和Nd∶GdVO4两种激光晶体的高温拉曼光谱.根据空间群理论指认了测定的特征谱线,依据晶格动力学理论导出了晶体热导率与积分拉曼散射强度的关系.计算了不同方向的晶体热导率,得到了与实验符合的结果.把Nd∶GdVO4晶体的高热导率归因于授主离子的质量和半径的增大,以及由此导致的晶体场效应的显著增强. 关键词： Raman光谱 激光晶体 热导率 空间群     

单、双掺钒酸钇晶体的Raman光谱与能量转移研究

文章采用双光栅单色仪(HRD-1),氩离子激光器的488.0 nm波长激发,分别测得室温下,激发光平行、垂直晶体c轴入射时,Tm3 ,Ho3 单掺和双掺钒酸钇晶体的拉曼光谱,对检测结果进行分析并探讨了对能量转移的影响.观测到对Ho3 :YVO4,激发光垂直c轴时的散射光强明显强于激发光平行c轴时的散射光强;由于488.0 nm波长靠近Ho3 的一个吸收峰,吸收和散射相互竞争,使475 cm-1被削弱,且外模振动展宽;测得样品最大声子能量集中在880cm-1附近.主要是(VO4)3-的A1g呼吸模引起的,表明与YAG基质一样,也是一种具有高声子能量的晶体.用808 nm激发,锁相放大器,PbS探头接收,测得双掺Tm3 :Ho3 :YVO4的2.09 μm荧光强度是单掺Tm3 ∶YVO4 1.85 μm的4/5,意味着Tm3 对Ho3 的敏化效率高达80%,因为Tm3 :YVO4的荧光谱与Ho3 吸收谱重合甚少,由辐射跃迁导致的能量转移可能性不大,因此Tm3 离子之间的交叉弛豫以及Tm3 的3F4与Ho3 的5I7之间近共振的能量转移主要是依靠声子辅助的无辐射跃迁.     

飞秒相干态相位差分光谱学

 理论上证明了测量脉冲对激发的相干态布居等价于测量单脉冲激发的感应极化,能同时获得瞬态相干光学过程的振幅与相位信息,发展了双通道飞秒脉冲对实验技术,提出了相位差分光谱实验方法。研究了半导体GaAs和稀土材料的飞秒相干态动力学过程,根据自相关曲线和样品信号的关系得到相位光谱。理论拟合得液氮温度下GaAs的激子退相时间为190fs;单晶Nd:YVO₄和粉末Nd:YAG 4f电子在室温下的退相时间为300fs。并研究了液氮温度下稀土材料原子核波包的动力学过程。     

激光二极管端面抽运Nd:YVO4实现1386 nm连续波激光输出

在Nd:YVO4晶体的4F3/2-4I13/2跃迁带内,除了1342 nm激光辐射之外,其它的跃迁谱线由于小的受激发射截面和强的寄生振荡,很难形成激光振荡.通过调整谐振腔损耗,获得了光纤耦合激光二极管端面抽运1386 nmNd:YVO4激光器激光连续输出.在抽运功率达到4.24 W时,得到了305 mW的1386 nm激光连续输出,最高输出功率下的斜效率为13.9%.实验中还观察到了1342 nm和1386 nm的双波长运转.根据抽运阈值能量和实验数据,计算得到了Nd:YVO4晶体中1386 nm激光辐射处的受激发射截面大约为(3±1)×10-19cm2.     

High peak power laser-diode-pumped passively Q-switched Nd:YVO4/Cr4+:YAG laser

In this paper, we report a high peak power passively Q-switched laser-diode-end-pumped Nd:YVO4/Cr4+:YAG laser polarized along the C axis, generating 4.23-W average power and 18-kW peak power (144-μJ pulse power) with 8.0-ns time duration (29.4-kHz repetition rate) at 1064 nm while the pump power is 21.2 W.     

1.5-mum emissions from laser-diode-pumped Nd-doped microchip solid-state lasers

1.5-mum emissions from Nd:YAG, Nd:YVO(4), and LiNdP(4) O>(12) microchip lasers pumped by laser diodes have been observed. These coherent emissions are attributed to the effect of high-energy modified lattice vibration owing to the existence of Nd ions as well as to stimulated intracavity Raman scattering enhanced by the microchip configuration. A four-wave mixing process involving two lasing fields and a Stokes field was identified as the generator of new adjacent 1.5-mu;m emission.     

LD泵浦全固态608.1nm和频激光器

本文报道了一种全固态腔内和频608.1 nm激光器。在激光谐振腔两个分臂中,两支激光二极管分别泵浦Nd: YVO₄和Nd: YAG晶体,分别选择1 342 nm波长(Nd: YVO₄晶体的⁴F_3/2-⁴I_13/2谱线)与1 112 nm波长(Nd: YAG晶体的⁴F_3/2-⁴I_11/2谱线)振荡并进行腔内和频。通过优化谐振腔设计,腔内两个波长获得了较好的模式匹配。在两个分臂的交叠部分,利用LBO I类相位匹配进行和频,获得和频608.1 nm激光输出。实验表明,当Nd: YVO₄与Nd: YAG晶体泵浦功率分别为600和740 mW时,获得了功率为23.8 mW、波长为608.1 nm激光输出,激光输出稳定、噪声低。利用本文提出的和频结构是获得608.1 nm激光输出较为有效的方法。     

Noncritically phase-matched fourth harmonic generation of Nd:glass lasers in partially deuterated KDP crystals

Noncritically phase-matched (NCPM) fourth harmonic generation (FHG) of Nd:glass laser radiation in partially deuterated dihydrogen phosphate (KD*P) crystals has been demonstrated. At an Nd:glass laser wavelength of 1053.0 nm, NCPM FHG is achieved in 70% deuterated KD*P at a crystal temperature of 18.5±0.1 °C. Tuning the fundamental laser wavelength from 1052.9 to 1053.2 nm, FHG in KD*P is NCPM by changing the crystal temperature from 17.9 °C to 20.5 °C. When driven with 2.4 J of second harmonic radiation in a 3 ns flat-top pulse, corresponding to 1 GW/cm(2) 2ω drive intensity, 1.9 J of fourth harmonic radiation was generated in a 6 mm long KD*P crystal, yielding a second to fourth harmonic energy conversion efficiency of 79%.     

Efficient, multiwatt, continuous-wave laser operation on the (4)F((3/2))-(4)I((9/2)) transitions of Nd:YVO(4) and Nd:YAG

We report multiwatt, diode-pumped cw operation on the (4)F(3/2)-(4)I(9/2) laser transition at 914.5 nm in Nd:YVO(4), for which an output power of 3.0 W and a slope of efficiency of 22.8% were achieved. For the corresponding laser transition of Nd:YAG at 946 nm an output power of 5.35 W and a slope efficiency of 40.2% were measured. By intracavity frequency doubling, an output power of 1.5 W at 473 nm was generated.     

Efficient generation of continuous-wave yellow light by single-pass sum-frequency mixing of a diode-pumped Nd:YVO(4) dual-wavelength laser with periodically poled lithium niobate

We report efficient generation of cw yellow light by use of single-pass sum-frequency mixing from a diode-pumped Nd:YVO(4) dual-wavelength laser with periodically poled lithium niobate. A diode-pumped Nd:YVO(4) dual-wavelength laser is implemented with a three-mirror cavity, and the optimum oscillation condition is obtained from theoretical analysis. We extracted 78 mW of power at 593 nm from 1.2 W at 1064 nm and from 1.0 W at 1342 nm in a beam with excellent quality. The output power could probably be increased to ~92 mW by antireflection coating of the crystal.     

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%。     

Multiwavelength visible laser based on the stimulated Raman scattering effect and beta barium borate angle tuning

We demonstrate wavelength-selectable visible emissions from a miniature crystalline laser that combines the stimulated Raman scattering(SRS) effect in an Nd:YVO4 crystal with intracavity frequency mixing in an angle-tuned beta barium borate(BBO) crystal.The presented laser is operating on demand at any one of three wavelengths in the green-yellow spectral region.Up to 600,560,and 200 mW output powers at 559,532,and 588 nm,respectively,are obtained from the continuous wave(CW) laser having a 18 mm long resonator and a 3.8 W laser diode end pumping.The pump threshold for each visible wavelength is less than0.4 W.