激光二极管抽运Nd∶YVO4/LBO腔内倍频5.3 W连续波激光器

报道了激光二极管双向抽运Nd∶YVO4 晶体、LBO腔内倍频、最大输出功率为 5 .3W的连续波绿光激光器。采用LBO晶体Ⅰ类非临界相位匹配 (NCPM) ,温度调谐 ,当抽运光功率为 2 0W时 ,获得了 5 .3WTEM0 0 模 5 32nm绿光输出 ,光光转换效率达 2 6 .5 %。并对绿光模式及输出功率随LBO晶体温度的变化关系进行了测量 ,与理论结果符合较好。     

无损伤超光滑LBO晶体表面抛光方法研究

传统的抛光LBO晶体的方法是选用金刚石抛光粉在沥青抛光盘上抛光。沥青盘易于变形不容易修整,金刚石粉特别硬容易损伤抛光晶体表面。抛光过程中,抛光盘和抛光粉的选择是非常重要的,直接影响到抛光效率和最终的表面质量。新的抛光LBO晶体的方法,其抛光过程是一个化学机械过程,抛光盘、抛光粉和抛光材料相互作用。选用两种抛光盘(培纶和聚氨酯盘),三种较软的抛光磨料(CeO2,Al2O3和SiO2胶体),并在LBO晶体的(001)面进行抛光实验。用原子力显微镜测量和分析了表面粗糙度。结果表明,使用聚氨酯盘和SiO2胶体能够获得无损伤超光滑的LBO晶体表面,其表面粗糙度的RMS为0.3nm。     

All-solid-state CW intracavity frequency-doubling Nd:Lu<Subscript>2</Subscript>O<Subscript>3</Subscript>/LBO red laser at 679.5 nm

We report an efficient intracavity second-harmonic generation (SHG) at 1359 nm in a non-linear optical crystal, LiB₃O₅ (LBO), performed with a diode end pumped continuous-wave (cw) Nd:Lu₂O₃ laser. In the case of a laser with a Nd:Lu₂O₃ crystal frequency-doubled with a LBO crystal cut for type I frequency doubling. A cw SHG output power of 462 mW has been obtained using a 10 mm long LBO crystal. The red power stability was 3.4% in 4 h.     

三硼酸锂晶体的多光子散射

本文报道三硼酸锂(LBO)晶体的瞬态前向相干多光子散射,实验表明LBO晶体内部同时发生x~(2)和x~(3)非线性相互作用过程,而未发现光耦合效应,测量了LBO晶体的光栅寿命上限.     

2.23 W diode-pumped Nd:YVO4/LBO Laser at 671 nm

A fiber-coupled diode-array-pumped, intracavity frequency doubled by a LBO crystal, high-power Nd:YVO₄ red laser at 671 nm has been developed in this paper. With incident pump power of 10.6 W, employing a type-I critical phase-matched LBO crystal, 2.23 W single-transverse-mode red light at 671 nm was obtained, with optical-to-optical conversion efficiency up to 21.0%.     

LiB3O5晶体高温拉曼光谱研究

研究了LiB₃O₅晶体在不同温度下(在300—1173K的温度范围)的拉曼光谱,分析了LBO晶体结构随温度变化的规律.随着温度的升高,LBO晶体的拉曼光谱谱峰都不同程度地向低波数方向移动,也存在不同程度的展宽,同时强度减弱.发现晶体在1100K存在明显相变,与LBO晶体的相图给出的1107K的相变温度基本相符. 关键词： 3O₅晶体')" href="#">LiB₃O₅晶体 高温拉曼光谱 相变     

全固态高功率连续单横模Nd:YVO4/LBO绿光激光器

报道了激光二极管泵浦的高功率连续单横模绿光激光器。考虑到激光晶体因吸收泵浦光而产生的热透镜效应,我们选择低掺杂浓度Nd:YVO4激光晶体,设计了V字型热不灵敏折叠式驻波谐振腔,利用I类非临界相位匹配LBO非线性晶体,当泵浦功率为23 W时,得到7 W单横模532 nm绿光输出功率,光-光转化效率为33%,长期功率稳定性优于1.6%(自由运转3小时)。     

Diode-pumped Nd:YVO<Subscript>4</Subscript> intracavity-doubled red laser at 693 nm

It is reported that efficient continuous-wave (CW) red laser generation at 693 nm in a LBO crystal at type-I phase matching direction performed with a diode-pumped Nd:YVO₄ laser. With incident pump power of 18.2 W, output power of 278 mW at 693 nm has been obtained using a 10 mm-long LBO crystal. At the output power level of 278 mW, the output stability is better than 2.9%.     

高压下LiB3O5晶体-非晶体相变的研究

 采用X射线粉末衍射和同步辐射能散X射线衍射技术，对LiB₃O₅（LBO）晶体进行了压致非晶化相变的研究，压力达45.1 GPa。实验结果表明，LBO存在两个中间相变，压力分别为5 GPa和15.8 GPa。而当压力增加到25~31.6 GPa时，LBO出现非晶态，这个非晶化相变是不可逆的。     

Generation of UV radiation at 335.5 nm based on frequency-quadrupling of a diode-pumped Nd:YVO4 laser

The generation of ultraviolet （UV） light at 335.5 nm based on frequency quadrupling of a diode-end- pumped Q-switched Nd：YVO4 laser at 1342 nm was demonstrated. KTP crystal was used for generation of wavelength of 671 nm by intracavity doubling and LBO （BBO） crystal was exploited for the subsequent external fourth harmonic generation （FHG）. With 6.3-W absorbed pump power and 10-kHz frequency repetition rate, the UV output power of 35 and 63 mW were obtained by using LBO and BBO as frequency quadrupling nonlinear crystals, respectively. The experimental results show that the conversion efficiency （red-UV） of 6.4% for BBO crystal is higher than that of 3.5% for LBO crystal, but the UV beam quality obtained by LBO crystal is better than by BBO crystal.     

Diode-pumped continuous-wave Nd<Superscript>3+</Superscript>:YAlO<Subscript>3</Subscript> intracavity-doubled red laser

It is reported that efficient continuous-wave (CW) red laser generation at 670 nm in a LBO crystal at type-I phase matching direction performed with a diode-pumped Nd³⁺:YAlO₃ (Nd:YAP) laser. With incident pump power of 15.6 W, output power of 273 mW at 670 nm has been obtained using a 10 mm-long LBO crystal. At the output power level of 273 mW, the output stability is better than 3.7%.     

1073 nm continuous-wave Nd:YVO₄ laser with Type I phase-matching LiB₃O₅

Continuous output from a Nd:YVO? crystal around 1073 nm was studied. The output of 1064 nm was suppressed with a Type I phase-matching LiB?O? (LBO) crystal rotated by 45°. With a pump power of 4.5 W, a 300 mW continuous output at 1073 nm was achieved for what we believe is the first time, and the optical-to-optical efficiency was 7%. With an adjustable LBO crystal, the wavelength is tunable from 1073.2 to 1073.5 nm. Even simultaneous output of 1066 and 1073 nm was realized by adjusting the LBO crystal. The experiments proved related theoretical analysis.     

高功率激光晶体加工技术的研究

针对高功率激光器中使用的激光晶体关键元件,开展了晶体的先进加工技术的研究。根据LBO及YCOB晶体材料的加工特性,选取了定向切割、研磨、预抛光、磁流变抛光、合成盘抛光和机械化学抛光的总体技术路线。对不同种类晶体加工设计了不同的工艺路线,开展了相关加工工艺研究。其中LBO晶体的面形收敛工艺主要采用磁流变抛光,YCOB晶体的面形工艺主要采用合成盘抛光。通过组合加工工艺,获得了高质量的晶体加工指标,LBO晶体透射波前0.12λ(λ=632.8nm),粗糙度0.77nm;YCOB晶体面形0.11λ,粗糙度0.68nm。确定了晶体元件的整体加工技术路线,并对整个工艺流程开展了工艺实验研究,取得了较好的实验效果,实现了激光晶体的高质量加工指标。     

All-solid-state Yb:KYW-LBO blue-green laser at 500 nm

It is reported that efficient continuous-wave (CW) blue-green laser generation at 500 nm in a LBO crystal at type-I phase matching direction performed with a Ti:sapphire laser-pumped Yb:KYW laser. With incident pump power of 8.7 W, output power of 138 mW at 500 nm has been obtained using a 10 mm-long LBO crystal. At the output power level of 138 mW, the blue-green output stability is better than 2.8%. The blue-green beam quality M ² values were equal to 1.25 and 1.18 in X and Y directions, respectively.     

1 W of blue 465-nm radiation generated by frequency doubling of the output of a high-power diode laser in critically phase-matched LiB3O5

Blue 465-nm radiation is generated by frequency doubling of the output of an InGaAs diode-laser oscillator-amplifier system in critically phase-matched LiB(3)O(5) (LBO). The diode-laser system emitted 4 W of single-frequency 930-nm radiation in a near-diffraction-limited beam (M(2)<1.2) . The laser power is enhanced to values of up to 150 W in a resonant external ring cavity. The LBO crystal is placed at a resonator internal focus. The frequency doubling in the LBO crystal generates blue radiation at 465 nm with a power of 1 W. The spectral width of the blue radiation is less than 3 MHz, and the value of the M(2) beam parameter is less than 1.2.     

Nonlinear optical properties of (B3O7)5- and (B3O6)3- groups

3 O₅ (LBO) crystal has been studied by using the bond valence theory of complex crystals. Chemical bond parameters and linear and nonlinear optical (NLO) properties of each type of constituent chemical bonds are quantitatively determined. Because of the different crystal structure characteristics of LBO from those of β-BaB₂O₄ (BBO), the two anionic groups, (B₃O₇)^5- in LBO and (B₃O₆)^3- in BBO, play different roles in contributions to their own total NLO tensor coefficients of LBO and BBO, respectively. By comparison, we find that planar (B₃O₆)^3- groups are the ideal structure model, leading to little cancellation of contributions of each kind of bond in these groups, and this gives us a useful guide to design new NLO materials in the future. Received: 24 January 1997/Accepted: 27 March 1997     

三硼酸锂(LBO)单晶的位错研究

本文叙述新型无机非线性单晶三硼酸锂(LBO)中位错的X射线衍射形貌观测和鉴定结果,探讨了位错形成的结构影响因素。 关键词：     

Frequency tripling of convergent beam employing crystals tiling in large-aperture high-energy laser facilities

In inertial confinement fusion, ultraviolet laser damage of the fused silica lens is an important limiting factor for load capability of the laser driver. To solve this problem, a new configuration of frequency tripling is proposed in this paper. The frequency tripling crystal is placed on downstream of the focusing lens, thus sum frequency generation of fundamental frequency light and doubling frequency light occurs in the beam convergence path. The focusing lens is only irradiated by fundamental light and doubling frequency lights. Thus, its damage threshold will increase. LiB₃O₅ (LBO) crystals are employed as frequency tripling crystals for its larger acceptance angle and higher damage threshold than KDP/DKDP crystals’. With the limitation of acceptance angle and crystal growth size are taken into account, the tiling scheme of LBO crystals is proposed and designed optimally to adopt to the total convergence angle of 36.0 mrad. Theoretical results indicate that 3 LBO crystals titling with different cutting angles in θ direction can meet the phase matching condition. Compared with frequency tripling of parallel beam using one LBO crystal, 83.8% (93.1% with 5 LBO crystals tiling) of the frequency tripling conversion efficiency can be obtained employing this new configuration. The results of a principle experiment also support this scheme. By employing this new design, not only the load capacity of a laser driver will be significantly improved, but also the fused silica lens can be changed to K9 glass lens which has the mature technology and low cost.     

Collinear phase-matching loci of LBO crystal in three-wave interactions

By choice of a reliable dispersion relation of LBO crystal, the loci of LBO crystal in second harmonic generation and sum-, difference-frequency generation (three wave interactions) are presented over its entire transparency region for the first time, on the basis of a new topological classification of phase-matching direction loci in biaxial acentric crystals. The result shows that there are totally 7 loci and 9 transitions for second harmonic generation, 12 loci and 15 transitions for three wave interactions at the room temperature 20 °C. The temperature dependence of LBO yields that the noncritical phase-matching loci of second harmonic generation varies slowly in the range of 20–300 °C, while the phase-matching loci in three wave interactions demonstrate varying locus distribution in the spectral region with temperature.     

Compact diode-pumped Nd:YVO4 intracavity-doubled red laser at 671 nm

A design of diode-pumped high efficiency Nd:YVO₄/LBO laser with a compact linear cavity was reported. Employing a type-II noncritical phase-matched LBO crystal, we generated 520 mW of 671 nm in single transverse mode at 6 W of incident pump power, the optical conversion efficiency being 8.7%.