599.2 nm diffuse band radiation generated by two-photon exciting molecular and atomic potassium

Diffuse band radiation around 599. 2 nm in K_2 was generated by the two photon pumping potassium dimers or by the two-photon resonant pumping atomic potassium with following atoms-molecules collision energy transfer. The pumping wavelengths are in a wide range of 697-745 nm. The relevant mechanisms were discussed.     

宽波段多步激发K_2-系统产生的钾原子高位态辐射

本文首次报道以690.0～715.0nm宽波段范围内任何波长的脉冲染料激光激发K_2—K系统,由高位钾分子与钾原子碰撞以及分子-原子的混合激发等过程而产生钾原子404.4,404.7和470.05～590.0nm波段内高位态辐射的实验结果,并对激发机制进行了探讨.     

钾蒸汽中双光子激发产生2~3∏_g—α~3∑_u~+扩散带受激辐射

本文报道了在K_2-K中通过双光子共振激发原子或双光子激发分子产生2~3∏_(?)—a~3∑_u~+扩散带辐射的实验结果,并对激发机制以及扩散带辐射随激发能量和温度的变化进行了讨论.     

Hybrid spin-exchange optical pumping of 3He

We demonstrate spin-exchange optical pumping of 3He using a "hybrid" K-Rb vapor mixture. The Rb atoms absorb light from a standard laser at 795 nm, then collisionally polarize the potassium atoms. Spin-exchange collisions of K and 3He atoms then transfer the angular momentum to the 3He with much greater efficiency than Rb-3He. For a K-rich vapor, the efficiency of the hybrid spin-exchange collisions approaches 1/4, an order of magnitude greater than achieved by pure Rb pumping. We present the first measurements of actual photon efficiencies (polarized nuclei produced per absorbed photon), and show that a new parasitic absorption process limits the total efficiencies for both hybrid and pure Rb pumping.     

不同泵浦光下Nd:GdVO4晶体输出特性

为研究808 nm和879 nm两种泵浦光对Nd:GdVO4晶体激光输出特性的影响,并比较两种不同波长泵浦所得连续输出光的效率高低,分析了Nd:GdVO4晶体的能级结构和两种泵浦光作用下的激光输出特性,发现在879 nm也有较强的吸收峰.用808 nm和879 nm两种不同波长泵浦Nd:GdVO4晶体的过程是不同的,808 nm泵浦是一种间接方式能量转移的过程,在此过程中有明显的热负载产生.而879 nm泵浦是将粒子直接激励到激光辐射上能级,降低无辐射弛豫过程产生的热量.从理论上可知,879 nm的泵浦量子效率要高于808 nm的泵浦量子效率,对减少晶体的热产生有很强的优势.实验中采用激光二极管端面泵浦Nd:GdVO4晶体直腔方案,研究了两种不同泵浦光泵浦Nd:GdVO4晶体以获得1 063 nm的连续光,得到了两种光抽运时的斜效率,发现在同样实验条件下,879 nm泵浦的输出光斜效率在小功率泵浦时略高于808 nm|而在大功率泵浦的情况下明显高于808 nm,最高达到38%.同时,在808 nm抽运时,实验上获得了1 341 nm波长的激光,为光通讯的应用提供了一种光源.     

Efficient Pumping Scheme by Direct Excitation of Upper Laser Level in Nd:CNGG

We report an efficient pumping scheme which involves a direct excitation of the upper lasing level of a four-level laser in a Nd-doped Ca₃(NbGa)_2-xGa₃O₁₂ (Nd:CNGG) by using a tunable Ti:sapphire, 700-920nm, cw pump source. The slope efficiency is improved from 10.5% of the traditional band pumping at 808nm to 21.8% of the direct pumping at 882nm. The influence of pumping wavelength on lasing is discussed. We present a scheme of double pumping for lasing.     

Short-pulse generation from a resonantly pumped NdAl3(BO3)4 microchip laser

We report on continuous-wave and subnanosecond passively Q-switched laser oscillation from a NdAl3(BO3)4 microchip laser operating at 1.06 microm. Efficient and stable laser operation is possible only when resonant pumping (4I9/2-->4F3/2 at 882 nm) is used instead of the traditional 4I9/2-->4F5/2 (808 nm) pumping. The improvement in laser performance is caused by a strong reduction in the pump-induced thermal loading, which is achieved by pumping directly into the emitting level.     

Diode-pumped continuous-wave eye-safe Nd:YAG laser at 1415 nm

We describe the output performance of the 1415 nm emission in Nd:YAG in a plane-concave cavity under traditional pumping into the 4F5/2 level (808 nm) and direct in-band pumping into the 4F3/2 level (885 nm). An end-pumped Nd:YAG laser yielded maximum cw output power of 6.3 W and 4.2 W at 885 nm and 808 nm laser diode (LD) pumping, respectively. To the best of our knowledge, this is the highest output power of a LD-pumped 1415 nm laser.     

Comparison of 885 nm pumping and 808 nm pumping in Nd:CNGG laser operating at 1061 nm and 935 nm

A Nd:CNGG laser operated at 935 nm and 1061 nm pumped at 885 nm and 808 nm, respectively, is demonstrated. The 885 nm direct pumping scheme shows some advantages over the 808 nm traditional pumping scheme. It includes higher slope efficiency, lower threshold, and better beam quality at high output power. With the direct pumping, the slope efficiency increases by 43% and the threshold decreases by 10% compared with traditional pumping in the Nd:CNGG laser operated at 935 nm. When the Nd:CNGG laser operates at 1061 nm, the direct pumping increases the slope efficiency by 14% with a 20% reduction in the oscillation threshold.     

Mode-locked Yb:KGW laser longitudinally pumped by polarization-coupled diode bars

Mode-locked operation of a simple Yb:KGW (potassium gadolinium tungstate) oscillator is described, providing 10 W at 1039 nm with a 290 fs pulse width. A polarization-coupled scheme is used for efficient longitudinal pumping by a pair of reshaped laser diode bars. With changes in cavity dispersion, the pulse width is adjustable from 134 to 433 fs, in a high-quality circular mode. A saturable absorber mirror provides self-starting operation, and the cavity is stabilized by the Kerr-lens effect.     

Two-photon hybrid resonance laser and photodissociation laser by two-photon pumping covering a wide wavelength region in the potassium vapor

This paper reports the results about the laser generation based on the two-photon hybrid resonance and on the photodissociation by two-photon pumping covering a wide wavelength region respectively. In the former, 3.66, 3.64, 3.16, 3.14, and 2.71 μm laser lines were obtained by collision energy transfer from a potassium dimer in an excited state to the potassium atom in the ground state, and then followed by the resonance excitation of the potassium atom from the 4P to 6S state. In the latter, 2.71, 3.14, and 3.16 μm dissociation laser lines were obtained by two-photon pumping of the potassium dimer covering a wide pumping range about 650 Å at the red wavelength region.     

Efficient laser performance of Nd:GdVO4 crystals grown by the floating zone method

Efficient laser performance is demonstrated with Nd:GdVO4 crystals grown by the floating zone method. With a 2-at. % Nd-doped crystal a slope efficiency of 67% is achieved with pumping at 808 nm. We also find that pumping at 879 nm with a bandwidth of 1.8 nm is practical for laser diode pumping. With this pumping level the slope efficiency reaches 78%. High-quality Nd:GdVO4 crystals are successfully grown with as much as 15-at.% Nd concentration by the floating zone method without inclusions or macroscopic defects. Homogeneity and high reproducibility of crystal growth are confirmed.     

Thermally-boosted pumping of Nd:LiYF<Subscript>4</Subscript> using Ti:Sapphire laser

We report for the first time (to our knowledge) a 1053 nm Nd:LiYF₄ (Nd:YLF) laser by directly pumping into the upper lasing level with a tunable Ti:sapphire laser. The results obtained for direct upper laser level pumping at 872 and 880 nm of Nd:YLF were compared with traditional 806 nm pump band excitation. Highly efficient 1053 nm continuous-wave (CW) laser emission under direct pumping at 880 nm in an 8 mm thick, 1.0 at % Nd:YLF crystal is obtained. The slope efficiency is improved from 39.1% for traditional pumping at 806 nm to 63.9% for direct pumping at 880 nm.     

Nd:YAG Lasers Operating at 1064nm and 946nm by Direct Pumping and Thermally Boosted Pumping

We demonstrate a 1064nm Nd：YAG laser by directly pumping into the upper lasing level with a tunable Ti：sapphire laser. The valid wavelength is demonstrated at 868.3nm, 875.2nm, 883.8nm, and 885.5nm, respectively. To our knowledge, this is the first time that 1064nm Nd：YAG laser pumped by 875.2nm laser. In addition, laser wavelength at 946 nm is also generated by direct pumping together with traditional pumping.     

All-Solid-State Nd:YAG Laser Operating at 1064nm and 1319nm under 885nm Thermally Boosted Pumping

We report a high-effciency Nd：YAG laser operating at 1064 nm and 1319nm, respectively, thermally boosted pumped by an all-solid-state Q-switched Ti：sapphire laser at 885 nm. The maximum outputs of 825.4 m W and 459.4mW, at 1064nm and 1319nm respectively, are obtained in a 8-ram-thick 1.1 at.% Nd：YAG crystal with 2.1 W of incident pump power at 885nm, leading to a high slope efficiency with respect to the absorbed pump power of 68.5% and 42.0%. Comparative results obtained by the traditional pumping at 808nm are presented, showing that the slope efficiency and the threshold with respect to the absorbed pump power at 1064nm under the 885nm pumping are 12.2% higher and 7.3% lower than those of 808rim pumping. At 1319nm, the slope efficiency and the threshold with respect to the absorbed pump power under 885nm pumping are 9.9% higher and 3.5% lower than those of 808 nm pumping. The heat generation operating at 1064 nm and 1319 nm is reduced by 19.8% and 11.1%, respectively.     

Upconversion Spectrum of Tm-doped Fiber Pumped by Multiwavelengths from 760 nm to 810 nm

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888nm LD泵浦Nd：LuV04倍频绿光激光器

报道了采用888nIn的激光二极管（LD）泵浦Nd：LuVO4晶体得到1066nm的激光输出,其对应能级跃迁为4F3／2→4I11/2。在注入的泵浦功率为18．2W时,获得了11．3W的近红外1066nm激光输出;然后采用非线性晶体LiB。O。（LBO）进行腔内倍频,获得了533nm的绿激光输出,输出功率为4．3W,其光-光转换效率为23．6％,光束质量因子为M2=1．3,4h功率稳定度优于3．7％。     

XeCl激光泵浦S2分子获得紫外激光振荡

本文报道利用ＸｅＣｌ准分子激光（３０８．１ｎｍ）横向泵浦硫双原子分子激光器，在近紫外谱区（３３０．９～３９０．０ｎｍ）的六条谱带上获得激光振荡。计算并测量了Ｓ２分子的吸收系数及小信号增益系数，从而确定了最佳泵浦波长。     

A numerical analysis of gain characteristics of Er-doped Al2O3 waveguide amplifiers

The gain characteristics of erbium-doped Al₂O₃ waveguide amplifiers are investigated by solving numerically rate equations with upconversion effects and propagation equations. We obtained the dependence of gain of erbium-doped Al₂O₃ waveguide amplifiers on the waveguide length, erbium concentration and pump power at different pumping wavelengths (980 and 1480 nm). The performance of amplifiers pumping at 1480 and 980 nm are compared. It is shown that 980 nm pumping has higher gain and higher pumping efficiency. The parameters of waveguide amplifiers have been optimized. A optical gain of 43 dB can be achieved for a optimum waveguide length of 8.25 cm and 5.8 × 10²⁰ cm^–3 Er concentration pumped with 100 mW at 980 nm, that is a gain of 5.2 dB/cm.     

高功率光纤激光器二级抽运技术的理论分析

从理论上分析了高功率光纤激光器直接抽运和二级抽运的斜率效率和热管理问题. 计算结果表明:波长为975 nm的激光直接抽运产生波长为1070 nm的激光时,理论斜率效率为80%,但当抽运光功率为10 kW时,在强制水冷条件下纤芯极值温度也难以降到150 ℃以下;在二级抽运技术中,波长为1018 nm的激光抽运产生波长为1070 nm的激光时,若采用传统的包层抽运技术,其斜率效率不足20%,如果抽运功率填充因子由0.0025提高到0.1,则理论上斜率效率可由18.5%提高到80.9%,从而总斜率效率由15.5 关键词： 二级抽运 功率填充因子 斜率效率 热管理