应用于金属焊接的光纤耦合输出2kW半导体激光光源

报道了一种高效节能、千瓦级光纤柔性输出半导体激光焊接光源。采用半导体激光合束技术,研制出2246W半导体激光合束光源,电光效率达43.6%;通过聚焦耦合,实现从600μm芯径、数值孔径0.2的光纤连续输出功率为2104W,光纤耦合效率达93.7%;在光纤输出端采用放大率1颐1的成像系统,到达工件表面的功率为2084W,光参量积为46.89mm·mrad,在束腰处测得光斑直径600μm,光功率密度为7.37×105 W/cm2,可以满足金属薄板焊接的激光加工要求     

Nd:Y2O3透明陶瓷4F3/2-4I11/2跃迁光谱及高效激光输出

报道了采用真空烧结法结合热等静压技术制备的Nd:Y₂O₃透明陶瓷的荧光光谱特性及相关激光输出。通过与Nd:YAG透明陶瓷的荧光光谱对比,表明Nd:Y₂O₃透明陶瓷的4F_3/2-4I_11/2跃迁光谱存在着多个增益相当的谱线,这更有利于实现同时双波长段激光振荡;不同斯塔克子跃迁光谱的离散特性有利于通过腔镜镀膜控制不同波长损耗,获得丰富的1.0~1.1 μm波段激光。利用简单的平平两镜腔结构完成进一步的实验,通过选择的输出镜片镀膜获得了输出功率3.62 W、转换效率40.4%的1074.6 nm和1078.8 nm的双波长输出和输出功率1.7 W、转换效率19.4%的1130.3 nm波长输出。     

半导体激光器列阵器件光束复合研究

文中针对半导体激光器列阵的波长复合和偏振复合技术开展了设计和实验研究。首先利用半导体材料波长易调节的特点,设计了AlGaInAs/GaAs/AlGaAs压应变量子阱结构,得到了760nm、800nm、860nm、930nm、976nm五个波长激射的半导体列阵激光器,同时设计了四个短波通滤波片参数,开展了半导体列阵激光器的多波长光束复合技术的实验研究;其次利用1/2波片和偏振复合棱镜将两束不同偏振状态的光束进行了复合,并设计了光束聚焦系统。最终实现了5个波长,10条半导体激光器列阵的光束复合,得到了196W的激光功率输出,总体效率为76%,其中,波长复合效率可以达到92.4%,输出聚焦光斑尺寸为144μm×1 330μm,聚焦光功率密度达到1.02×105W/cm2,与单条半导体激光器列阵相比,合束光的光功率密度提高了4.3倍。     

微波辅助烧结Al掺杂ZnO陶瓷的缺陷和光学性能研究

采用微波辅助烧结法在空气气氛中以1100℃烧结20 min制备出不同Al₂O₃掺杂量（摩尔分数0%～6%）的ZnO陶瓷。通过XRD、SEM、霍尔实验、UV-Vis光谱、Raman光谱、PL光谱的表征,研究了Al₂O₃掺杂量的变化对微波辅助烧结ZnO陶瓷的物相结构、微观组织、电学性能、光学性能的影响。实验结果表明,Al₂O₃掺杂并没有改变ZnO陶瓷的六方纤锌矿结构,随着Al₂O₃掺杂量的增加,在ZnO晶界处逐渐形成ZnAl₂O₄尖晶石相,ZnO晶粒尺寸逐渐减小;微波辅助烧结所制备ZnO陶瓷的室温电阻率和光学带隙随Al₂O₃掺杂量的增加呈先减小后增加的趋势;当Al₂O₃掺杂量为摩尔分数4%时,所制备ZnO陶瓷的综合性能最好,样品的室温电阻率为1783Ω·cm,光学带隙为3.04 eV;随...     

808 nm准连续半导体激光迭阵偏振耦合技术

利用激光偏振原理将两束同一波长不同偏振态的激光束耦合以获得更高功率输出,是目前国际研究的热点之一.通过激光偏振及偏振转换元件的理论分析,给出了偏振耦合技术的实验原理、装置及关键技术,并通过实验将20%占空比准连续808 nm两半导体激光迭阵进行耦合.自行设计光学系统对光束进行扩束、聚焦,实现输出光斑2 mm×2 mm,效率达60%.     

稀土氧化物对Al2O3-ZrO2激光熔覆层组织与性能影响研究

为了解决在钛合金表面通过激光熔覆技术制备得到的Al₂O₃-ZrO₂陶瓷涂层脆性大、易开裂的问题,有效提升钛合金性能,扩大其使用范围,采取在熔覆层材料中添加稀土氧化物CeO2的方法,对Al₂O₃-ZrO₂陶瓷熔覆层的裂纹敏感性进行了改善。通过分析熔覆层宏观、微观组织,测试熔覆层性能,研究CeO2含量对熔覆层裂纹敏感性的影响规律,探究CeO₂调控辅助激光熔覆制备Al₂O₃-ZrO₂陶瓷涂层最佳含量,揭示稀土氧化物对熔覆层裂纹敏感性影响的作用机理。结果表明：通过添加稀土氧化物调控,熔覆层裂纹数量明显减少,熔覆层裂纹控制主要归功于稀土元素对熔覆层组织的细晶强化效应;当CeO₂质量分数为0.8%时,熔覆层微观组织最为致密,对裂纹抑制作用最为明显;熔覆层断裂韧性相较未添加稀土调控辅助时有明显提高,从4.1 MPa·m^1/2提高至7.3 M...     

半导体激光器双波长光纤耦合模块的ZEMAX设计

为了发挥单管半导体激光器的优势,获得光纤耦合模块多波长、高功率、高亮度的光束输出,利用ZEMAX软件仿真模拟,设计了一种单管光纤耦合模块。此模块将32支输出波长分别为915 nm、975 nm,输出功率为15 W的单管半导体激光器,经过微透镜组快慢轴光束整形、空间合束、偏振合束、波长合束以及光束聚焦等一系列工艺后,耦合进芯径200 m、数值孔径0.22的光纤。模拟结果显示,光纤输出功率467.46 W,光纤前后耦合效率大于98.47%,总耦合效率高于97.39%,光功率密度高于12.86 MW/（cm2sr）,达到了泵浦激光器和功率型器件的性能要求。使用Solidworks软件设计了相应的底板结构,并结合ANSYS软件进行散热模拟分析,结果显示该模块散热性能良好,可行性较高。     

千瓦级高光束质量半导体激光线阵合束光源

低光束质量严重限制了大功率半导体激光器的应用,为了满足日益增长的工业和国防领域应用需求,发展兼具高功率和高光束质量激光输出的半导体激光光源具有重要意义。采用线阵合束方式集成20个传导热沉封装半导体激光单元,结合斜45°柱透镜阵列整形方法和准直技术,直接均衡激光束快慢轴方向的光斑和发散角,通过波长合束和偏振合束,研制出一种可实用化、连续输出功率1030W、快慢轴方向光参量积分别为18.3mm.mrad和17.7mm.mrad、最大电-光转换效率44%的808nm和870nm双波长半导体激光合束光源,实现了高效率、高功率和高光束质量激光输出,可作为直接光源应用于工业和国防领域。     

大功率半导体激光列阵单光纤耦合技术

利用阶梯反射镜整形技术和偏振合束及波长合束技术成功将两只波长为808nm和两只波长为980nm的40W大功率半导体激光器光束进行混合,最后得到输出功率为95.8W、耦合效率为60%的双波长大功率半导体激光列阵单光纤耦合模块,光纤芯径为400μm,数值孔径为0.22.     

双波长高功率半导体激光器波长耦合技术

介绍了非相干耦合技术中波长耦合原理及关键技术,根据波长需要设计耦合器件,自行设计了光学系统对光束进行扩束聚焦,通过实验将808nm和980nm两半导体激光迭阵光束通过此技术进行合束,最终实现更高功率输出,耦合效率为80%,光斑大小为2mm×2mm,可满足将半导体激光器直接应用于熔覆、焊接等场合。     

Improved Ti:sapphire laser performance with new high figure ofmerit crystals

The continuous-wave (CW) laser performance of Ti:Al₂O ₃ crystals with high figure of merit is described. Using a 0.1% Ti:Al₂O₃ crystal (FOM=1000), output powers of 3.5 W at 800 nm are obtained, pumping with a 9.6 W argon ion laser operating multiline. Continuous tunability of the CW Ti:Al₂O ₃ laser extending from 665 to 1070 nm is also demonstrated for a 5 W pump power     

Blue-light generation by frequency doubling of a laser diode in aperiodically domain-inverted LiTaO3 waveguide

The authors report quasi-phase matched second-harmonic generation by frequency doubling of a laser diode in LiTaO₃ having a first-order periodically domain-inverted region and proton-exchanged channel waveguide. A deep domain-inverted region and a low-loss channel waveguide with strong confinement are formed by using proton-exchange and quick heat treatment techniques. Utilizing this structure, a high normalized conversion efficiency of 157%/W is obtained with a Ti:Al₂O₃ laser. Using a temperature-controlled laser diode and AR coating on the input and output facet of the waveguide, the laser diode maintains single-mode oscillation without any mode hopping. Consequently, 1.1 mW of blue light is obtained at a wavelength of 436.5 nm     

A two-wavelength, passively self-injection locked, CW Ti3+:Al2O3 laser

We have demonstrated that passive self-injection control is very effective in a CW Ti³⁺:Al₂O₃ laser to produce high efficiency (η~15%), narrow-line, two-wavelength emission. Light reinjection is achieved with an original high-resolution two-wavelength selector combining an interference wedge and a grazing incidence grating. The device operates outside the main nonselective laser cavity; thus avoiding insertion losses and optical damage problems. A 1.5 W, background free, total output power has been obtained simultaneously at two narrow laser lines (fwhm: 8 pm), independently tunable over 50 mn. The two laser lines can be emitted in a single beam or in two separated beams. Self-injection wavelength control has been demonstrated both for linear and for ring laser cavities. In the latter case, unidirectional behavior is also obtained in the same way. Single-step (5s²S_1/2-5P²P_1/2,3/2 ) and two-step (5s²S_1/2-5p²P_3/2-5d² D_3/2,5/2) excitation of atomic rubidium vapor has been performed with our original laser device     

三波长自由切换激光系统

针对工程应用中对多波长激光源的使用需求,提出了一种可自由切换三种波长输出的激光系统。高稳定、高光束质量抽运源通过由电光晶体和偏振分光棱镜组成的波长切换装置,实现首次波长切换;光参量振荡器输出的闲频光和信号光通过由机械调控的光学陷阱实现二次波长切换;再采用光路折叠和合束镜多波段镀膜技术,最终实现共光路三波长激光自由切换输出。当抽运功率为14 W时,信号光和闲频光功率超过5 W,光光转换效率为35.9 %。三种激光的输出功率不稳定度均小于2 %。两次波长切换都可在全温度范围内进行,能量关闭程度接近100 %,切换速度分别为纳秒级和毫秒级。经过监测,系统能够长时间稳定工作,具备工程应用能力。     

调Q锁模运转的全固态Tm:LuAG陶瓷激光器

采用垂直生长法制备的氧化石墨烯（Graphene oxide, GO）作为可饱和吸收体,利用典型“X”型折叠腔在全固态Tm:Lu₃Al₅O₁₂(Tm:LuAG)陶瓷激光器中实现了调Q锁模运转。以790 nm激光二极管(Laser diode, LD)作为泵浦源,当泵浦功率大于8 W时,激光器进入稳定的调Q锁模状态。当输出镜透过率为5%时,连续光最高输出功率为714 mW,斜效率为4.94%。当泵浦达到16 W时,激光器最大输出功率为200 mW , 光谱中心波长为2024 nm,脉冲宽度约为695 ps,对应的锁模脉冲重复频率为108.7 MHz,调Q包络中锁模脉冲的调制深度接近100%。该2 μm超短脉冲激光器在生物医学和激光通讯等领域具有非常重要的应用。     

Ho∶YLF激光泵浦的长波红外ZnGeP2光参量振荡器

以2.05μm Ho∶YLF激光器作为光源,泵浦了长波ZnGeP₂光参量振荡器,实现了高效率、高重复频率的长波激光输出。激光器输出的峰值波长为8.1μm,最大输出功率为3.2 W@10 kHz,泵浦激光到长波激光的光光转换效率为12%,斜效率为19.3%,激光单脉冲宽度为27.11 ns,单脉冲能量为0.32 mJ,单脉冲峰值功率为11.8 kW,X方向的光束质量因子为4.5,Y方向的光束质量因子为4.2。     

Polarization Dependence of Femtosecond Optical Kerr Signals in Bismuth Glasses

Using the optical Kerr shutter (OKS) technique with an 800-nm femtosecond laser, we demonstrated that the response time of the glass was less than 85 fs. The nonlinear refractive-index of Bi₂O₃-B₂O₃-SiO₂ (BI) oxide glass was estimated to be about 2.93times10^{- 15}cm²/W. By measuring the dependence of the OKS signals on the pump power and on the polarization angle between pump and probe beams, we found that the OKS signals arose mainly from the photoinduced birefringence effect, and the polarization dependence of the signals was dependent on the intensity ratio of the pump beam to the probe beam.     

Single-frequency Ti:Al2O3 ring laser

Over 500 mW of single-frequency power has been obtained from a Ti:Al₂O₃ ring laser pumped by 10 W (all lines) from an argon ion laser. The ring laser can be tuned from 750 to 850 nm while maintaining more than 100 mW in single-frequency operation without realignment or a change of optics. The free-running frequency stability of the laser is 3 MHz. Thermal effects cause changes in the ring cavity parameters, limiting the output power. This ring laser has also been operated with an acoustooptic mode locker to obtain 200-ps mode-locked pulses at 250 MHz with nearly the same average power as in single-mode operation