974nm半导体激光器的光纤耦合研究

根据半导体激光器和单模光纤模场分布特点,用模式耦合理论研究了单模光纤与半导体激光器的耦合,结果表明将光纤端面制作成楔形微透镜可以使光纤与半导体激光器的耦合满足模场匹配和相位匹配的要求。用遗传算法对楔形光纤微透镜参数进行优化,得到楔角为88°,柱透镜半径为3.44μm,耦合距离为6.13μm时耦合效率达到最佳值,用Zemax光学仿真软件对耦合模型进行仿真,得到耦合效率为88.9%,耦合好的模块经激光点焊及高低温环境测试后,得到最大耦合效率为81.36%。实验结果与仿真结果相差不大,耦合输出功率满足了作为光纤激光器种子源的功率要求。     

大功率半导体光放大器的耦合工艺研究

针对高速大功率半导体激光器,设计了主振激光器与半导体光放大器分立集成的高速大功率半导体激光器组件,并对其中半导体光放大器(SOA)的光纤耦合技术进行了研究,采用单模光纤耦合技术以及光路可逆原理设计了SOA的注入端耦合光路,实现了主振激光器到SOA的高效注入,耦合效率大于50%,采用微透镜组技术设计了SOA输出端的耦合光路,实现了Φ62.5μm的光纤耦合输出238mW。同时针对光纤耦合工艺,利用Ansys软件对耦合结构进行了激光焊接耦合工艺的热应力分析,得到了优化的焊接工艺条件,并对耦合中存在的应力进行了释放处理,有效提高了输出功率的稳定性。     

大功率半导体光放大器的耦合工艺研究

针对高速大功率半导体激光器,设计了主振激光器与半导体光放大器分立集成的高速大功率半导体激光器组件,并对其中半导体光放大器（SOA）的光纤耦合技术进行了研究,采用单模光纤耦合技术以及光路可逆原理设计了SOA的注入端耦合光路,实现了主振激光器到SOA的高效注入,耦合效率大于50%,采用微透镜组技术设计了SOA输出端的耦合光路,实现了Φ62.5μm的光纤耦合输出238mW。同时针对光纤耦合工艺,利用Ansys软件对耦合结构进行了激光焊接耦合工艺的热应力分析,得到了优化的焊接工艺条件,并对耦合中存在的应力进行了释放处理,有效提高了输出功率的稳定性。     

楔形光纤排与半导体激光器耦合技术研究

首先从半导体激光器列阵的发光特性出发,利用楔形光纤排对大功率半导体激光器列阵光束进行耦合,最后得到一只含有19个纤芯,每个纤芯为200μm,数值孔径为0.12的大功率半导体激光器光纤耦合模块,输出功率为32.48W, 耦合效率为81.2%.     

光纤耦合高功率半导体激光器系统

介绍了利用多模光纤同空间列阵半导体激光器实现有效耦合,再将光纤组合后输出的技术.阐述了半导体激光器与光纤耦合的一般理论.对半导体激光器的发散角、多模光纤和半导体激光器耦合的常规技术进行了分析.介绍了多模光纤和半导体激光器耦合的新技术,即在半导体激光器与光纤之间加光纤微透镜的耦合技术.这种技术可有效地提高耦合效率,使之达到80%以上.将空间列阵半导体激光器通过光纤耦合后组合输出是使半导体激光器得以实际应用的有效途径.(PC5)     

基于DFB激光器的楔形截顶光纤微透镜耦合结构

为了解决分布式反馈激光器的光发射次模块耦合封装中存在最大耦合效率局限的问题, 采用楔形截顶光纤微透镜代替分立式透镜的直接耦合的方法, 得到斜面倾角0.6rad、耦合距离60μm、半宽度15μm的楔形截顶光纤端面模型。在此基础上与分立式和直接耦合进行对比, 讨论了纵向、横向和角度偏移误差。结果表明, 纵向耦合距离在-21.45μm~56.79μm, 角向耦合角度在-8.3°~8.5°, 耦合效率始终大于70%;结构整体容忍度较高, 耦合效率达84.40%。该研究可为下一代分布式反馈激光器的次发射模块耦合封装器件提供新的解决方案。     

激光器与单模光纤球透镜耦合的蒙特卡洛分析

为了研究半导体激光器与单模光纤在采用球透镜耦合方式的封装过程中不同耦合参量对耦合效率的影响,建立了半导体激光器与单模光纤通过球透镜耦合的光传输模型。基于ABCD矩阵和高斯光束与单模光纤耦合理论,计算了半导体激光器与单模光纤的球透镜耦合效率,以光功率下降0.5dB为评判标准,给出了在透镜半径为0.5mm时的各参量容忍度。采用蒙特卡洛分析方法,结合耦合效率计算模型,模拟仿真了各参量满足正态分布时的耦合效率分布状况。结果表明,能达到的最大耦合效率为0.616,最大概率耦合效率为0.585,参量区间缩小一半对耦合效率的提升较明显,但进一步缩小参量区间对耦合效率的提升不明显。此研究方法对激光器件封装过程中的对准单元精度选取与耦合效率预估具有指导意义。     

一种实现半导体激光器和多模光纤耦合的实用技术

文中提出了一种实现半导体激光器和多模光纤耦合的实用化方法。用一段直径为600μm的裸石英光纤代替柱透镜对半导体激光器输出光束进行准直整形;用半球端光纤对光束进行聚焦后直接实现和光纤耦合,来代替聚焦透镜和光纤耦合的环节。研究表明:采用该方法耦合效率在80. 0%左右,同时最大程度解决了使用柱透镜和聚焦透镜的组合透镜耦合系统时存在的调试与封装困难的问题,且工艺稳定,因而有着广泛的应用前景。     

半导体增益芯片与微透镜光纤耦合效率研究

光纤光栅外腔半导体激光器一般采用波导-光纤的直接耦合方式,光纤与增益芯片的耦合效率对光纤光栅外腔半导体激光器性能影响较大.为了讨论在采用不同类型光纤微透镜时对准误差对耦合效率的影响,寻找最佳微透镜类型,指导器件的设计和装配,分析了锥形和半球形光纤透镜的光线最大接收半角,利用ZEMAX软件进行模拟仿真,得到了两种光纤微透镜分别在位置误差和角度误差下的耦合效率曲线图.结果表明,锥形光纤透镜耦合效果更好,更适合应用于光纤光栅外腔半导体激光器.     

高亮度半导体激光器泵浦光纤耦合模块

采用一种阶梯排列结构的单管激光器合束技术制成了高亮度半导体激光器光纤耦合模块,可用于泵浦掺Yb3+大模场双包层光纤激光器。利用微透镜组对各单管半导体激光器进行快慢轴准直,在快轴方向实现光束叠加,然后通过两组消球差设计的柱面透镜组分别对合成光束快慢轴方向进行聚焦,耦合进入光纤。实验中将6只输出功率为6 W 的976 nm单管半导体激光器输出光束耦合进芯径为105 m、数值孔径为0.15的光纤中,当工作电流为6.2 A 时,光纤输出功率达29.0 W,光纤耦合效率达到80.1%,亮度超过4.74 MW/cm2-str。     

A new scheme of conical-wedge-shaped fiber endface for coupling between high-power laser diodes and single-mode fibers

A new scheme for the lensed fiber employing a conical-wedge-shaped fiber endface (CWSFE) for coupling between the high-powered 980-nm laser diodes and single-mode fibers (SMFs) is proposed. The CWSFE was fabricated by following grinding and polishing techniques and then through heating in a fusing splicer to form an elliptical microlens endface. A coupling efficiency of 84% has been demonstrated. The higher coupling efficiency of the CWSFE lensed fiber was attributed to the better matching of both the elliptical Gaussian field distribution and the aspect ratio between the laser source and the fiber. In comparison to other fabrication techniques of lensed fiber used in high-power diode lasers, the advantages of this novel CWSFE structure are the ability to control over two axial curvatures and a small fiber offset through grinding and polishing processes to form a good elliptical endface. The results of this study have led to the development of a simple and reproducible fabrication process for achieving a high-yield and high-coupling CWSFE structure that is suitable for use in commercial high-power pump laser modules.     

A new scheme of a lensed fiber employing a wedge-shapedgraded-index fiber tip for the coupling between high-power laser diodesand single-mode fibers

A novel lensed fiber employing a wedge-shaped graded-index fiber (GIF) is proposed. The characteristic of coupling loss as a function of the aspect ratio is numerically investigated. When the aspect ratio is seven, the coupling loss of a wedge-shaped GIF and a conventional wedge-shaped SMF are 0.22 dB and 0.60 dB, respectively, and when the aspect ratio is 13, they are 0.5 dB and 2.4 dB. The tolerance to laser diode (LD)-fiber displacement is also numerically investigated, and it is confirmed that the proposed fiber has larger tolerance than a conventional wedge-shaped single-mode fiber (SMF). The performance of the new lensed fiber is also experimentally verified     

提高大功率激光器与光纤耦合效率的新型光腔

提出并实现了一种新型多有源区隧道级联大光腔半导体激光器,增大了半导体激光器激射窗口的高度,得到低于20°的垂直发散角,从而显著提高了激光器与光纤的耦合效率。将其与多种形式和规格的透镜光纤进行测试,耦合效率可以提高30%以上。     

复合型微通道热沉设计与制作技术研究

从大功率半导体激光器可靠性封装和应用考虑,利用商用有限元软件Abaqus与CFdesign对微通道热沉材料、结构进行优化设计,结合相应的制造工艺流程制备实用化复合型微通道热沉。微通道热沉尺寸为27 mm×10.8 mm×1.5 mm,并利用大功率半导体激光阵列器件对所制备热沉进行散热能力、封装产生的"微笑效应"进行了测试,复合微通道热沉热阻约0.3 K/W,"微笑"值远小于无氧铜微通道封装线阵列,可以控制在1μm以下。复合型微通道热沉能满足半导体激光阵列器件高功率集成输出的散热需求与硬焊料封装的可靠性要求。     

Impact of near-end residual reflectivity on the spectral performance of high-power pump lasers

Abnormal spectral characteristics are observed in high-power semiconductor pump laser modules with ultralow chip front-facet reflectivity levels. We have identified the root cause as destructive interference in an external-cavity reflection from an antireflection (AR) coated fiber tip. This suppressive external cavity imposes a practical limit on the lower desirable bound for front-facet AR coatings for high-power lasers and uncooled fiber Bragg grating stabilized semiconductor devices.     

Laser-to-fiber coupling via optical fiber up-tapers

A method for coupling single-mode fiber to laser diodes with high efficiency and greatly reduced alignment sensitivities is discussed. It consists of a spherical ruby lens and a single-mode optical fiber up-taper. Using a double-channel planar buried heterostructure (DCPBH) laser, more than 60% of the light from the lens is coupled into a single-mode fiber via the taper. The lateral and axial tolerances of the lens-taper arrangement are reduced by factors of 20 and 1000 times, respectively, compared with laser coupling to a lensed single-mode fiber. These relaxed alignment tolerances have the potential to allow the taper to interface with a hermetically-sealed laser-lens package via a window and a connector on the package exterior     

微透镜光纤在半导体激光器中的应用研究

对几种典型的半导体激光器与光纤的耦合特性进行分析,提出提高耦合效率所采用的微透镜光纤的结构.介绍熔拉型、化学蚀刻型、研磨抛光型、切削型、自聚焦光纤型和铸模型等微透镜光纤的制作原理和工艺以及目前达到的指标,并对各种形式的透镜光纤进行了评价.提出了提高耦合效率和失调容差、降低插损的新思路.     

楔形光纤与半导体激光器的耦合研究

结合半导体激光器的特点,通过对高斯光束发散特性的分析,得到激光器的模场分布特点,指出与激光器最佳耦合的光纤外形为楔形光纤,楔形光纤的楔角与尖端半径决定着耦合效率。实验表明,楔形光纤与半导体激光器的耦合效率明显优于尖锥形光纤与半导体激光器的耦合。用楔角为104°,尖端半径为3.3μm的楔形光纤进行测量,测得最大耦合效率达到87.2%。     

Thermal management strategies for high power semiconductor pump lasers

Semiconductor pump lasers are an important component in erbium-doped fiber amplifiers and Raman amplifiers. Thermal management has become one of the major obstacles of pump laser development. Understanding of the thermal behavior of high-power laser packages is crucial to the thermal design and optimization of pump lasers. In this paper, we report on the thermal characteristics of a high-power pump laser and discuss the issues associated with heat dissipation. The thermal management of high-power pump laser modules mainly consists of three aspects. One is the thermal resistance reduction which reduces bulk temperature rise in the laser diode chip. The second is facet temperature control, and the third is the thermoelectric cooler (TEC) coefficient of performance improvement. In this paper, the approaches to reduce thermal resistance and facet temperature at the chip level and package level will be reviewed, and the thermal design and optimization of the package assembly to improve the TEC coefficient of performance will be discussed. The thermal resistance of a pump laser could be reduced up to 40% by the proper design of the laser chip and epi-down bonding. An unpumped window design in the pump laser diode is proven to be very effective in reducing the facet temperature and increasing the catastrophic optical mirror damage level. Assembly and package optimization can provide more uniform temperature distribution on TEC cold plate which is critical in improving the TEC coefficient of performance.     

Fields in extended cavity lasers

The electromagnetic fields for an extended-cavity laser are described precisely and in detail. The extended-cavity laser consists of a semiconductor laser diode with a partially reflecting coating on one facet and an antireflection coating on the other coupled by radiation through a lensed-fiber, single-mode guide to another partially reflecting coating terminating a narrow-wavelength filter. The formulation is based on the Lorentz reciprocity theorem, the fields are described by angular plane-wave spectra, and the equivalent transmission line representation is used to determine the fields reflected and transmitted by partially reflecting and antireflection coatings. The design of antireflection coatings is considered in detail, and a formula which gives the optimum distance from the diode antireflection coating to an inline lensed fiber is derived