腔面镀膜对1342 nm分布反馈半导体激光器输出功率的影响

为提高1342 nm 分布反馈（Distributed Feedback, DFB）半导体激光器的输出功率,设计了三种腔面膜膜系组合。采用电子束蒸发镀膜技术对该激光器进行了腔面镀膜,并测试了其在三种膜系组合下的输出功率。结果表明,采用增透膜为基底(Sub)/Al₂O₃/Ta₂O₅/空气(Air)、高反膜为Sub/(Al₂O₃/Si)³Al₂O₃/Air的腔面膜膜系组合时,激光器的输出功率最高。前腔面反射率为0.2%,后腔面反射率为98.6%。在260 mA的直流电流下,平均输出功率达到了85 mW以上（增加了85.6%）,斜率效率提升了82.9%。通过采用此膜系组合进行激光器腔面镀膜,可以大幅提升1342 nm DFB半导体激光器的输出功率。     

808nm大功率半导体激光器腔面膜优化设计

推导出半导体激光器前腔面和后腔面上的入射激光功率之比,阐述了后腔面膜电场强度优化设计的重要性.从实际问题出发在以往腔面膜的研制基础上,选择适合制备808nm大功率半导体激光器腔面的镀膜材料.给出了镀制腔面膜过程中会出现的种种关键问题的解决方法,针对各种具体应用提出几种前腔面设计方案.得到后腔面电场强度优化设计的膜系.     

大功率半导体激光器腔面膜的场强分布优化

为了提高半导体激光器腔面膜的激光损伤阈值,进而提高激光器输出功率,对激光器的灾变性光学镜面损伤产生的原因进行了探讨。根据损伤原理,将高反膜中场强最大处移出界面,采用光学传输矩阵,对厚度连续变化的界面场强和反射率进行了计算,得到优化高反膜系,优化膜系减小了界面处的光场对薄膜的损伤。采用改进后束流密度更大的LaB6作为阴极原位等离子源,对离子源清洗的参数进行了优化。薄膜制备前期使用离子清洗的方法在真空环境下对腔面进行去氧化,在制备过程中使用电子束蒸发离子源辅助沉积,并测试了薄膜在高温高湿环境下的稳定性。使用该优化的膜系和清洗方法制备的半导体激光器,在准连续输出时,功率由4.6 W提升到了7.02W,工作电流由5A提升到了8A。     

808nm激光器端面镀膜技术

通过对AlGaAs／GaAs808nm半导体激光器谐振腔的前后端面分别蒸镀Ta2O5／SiO2膜系高反膜和Al2O3单层增透膜，使得前后端面的反射率分别达到11％和98．42％。器件在同一驱动电流下镀膜后的输出功率比镀膜前增加了一倍多，同时镀膜还有效地保护了端面，延长了器件工作寿命。     

808 nm掺铝半导体激光高损伤阈值腔面膜制备

研究了808 nm量子阱脊型波导结构掺铝半导体激光器在空气中解理不同镀膜方法对激光损伤阈值的影响.将半导体激光器管芯分别采用前后腔面不镀膜、前后腔面镀反射膜和前后腔面先镀钝化薄膜,再镀腔面反射膜的方法进行对比.测试半导体激光器输出功率的结果表明:腔面镀钝化薄膜的方法比只镀腔面反射膜的方法的激光损伤闽值高36%,并且能有效防止灾变性光学镜面损伤,同时,还分析了半导体激光器管芯和光学薄膜之间发生的物理效应.在大功率半导体激光器芯片腔面上镀钝化薄膜是提高其激光损伤阈值的一个行之有效的方法.     

优化反射率以增强半导体激光器输出功率

在考虑了俄歇效应的情况下，用行波速率方程组研究了半导体激光器的输出功率与端面反射率的关系。给出了在不同偏置电流下使激光器输出端输出功率最大所需要的端面反射率。利用主动监控法在１．３μｍＩｎＧａＡｓＰ半导体激光器端面上完成了这种功率增强膜的镀制，在所选择的６０ｍＡ工作电流处，镀膜后激光器的输出功率增加了１３０％。     

大功率半导体激光器腔面处理方法

介绍了采用非注入电流腔面和透明窗口减小腔面电流的方法。减小腔面非辐射复合的方法包括采用高真空下解理、镀膜防止腔面氧化;采用真空等离子洗或化学气体腐蚀清除腔面氧杂质沾污。论述了合适的腔面膜系组合和膜系组分有利于减小腔面膜层应力,改善散热能力。指出将抑制腔面电流、防止腔面氧化等方法组合,再加上合理的结构设计和热管理等综合应用,以及将半导体材料-镀膜膜层交界面处于光驻波波谷,可有效提高器件的灾变光学镜面损伤(COMD)阈值。     

腔面低反射大功率半导体激光器阵列

光束质量问题是制约半导体激光器应用的主要因素,采用出光面蒸镀低反膜LD阵列半导体激光器阵列锁相技术较好地解决了这个问题.本文设计并制作了高反膜系和极低反膜系,获得了高阈值的LD阵列.本文的低反膜系有大的带宽和小于0.2%的剩余反射率,易于工艺实现,LD阵列的阈值电流密度达到480A/cm2.     

980nm半导体激光器高反膜的优化设计

通过软件模拟和理论分析,对980BITI半导体激光器高反膜的结构进行了优化设计。选定Ta2O5／SiO2作为980nm半导体激光器的高反膜材料,通过软件TFCalc进行仿真,对3种不同膜系结构的反射率和电场强度进行了对比分析,对镀膜后和未镀膜的器件分别进行测试。仿真结果表明：膜系结构为A12O3（Ta205／SiO2）^7 Ta2O5的高反膜性能良好,镀膜后的阈值电流减小了20mA左右,斜率效率从0．48增加到了0．86。     

大功率底发射VCSEL出光窗口增透膜的研究

在大功率垂直腔面发射激光器(VCSEL)出光窗口镀制了HfO2增透膜,其透过率达到99.9%.对镀膜材料以及透过率方面进行了比较,介绍了增透膜的制作过程.镀膜后直径为600μm的底发射VCSEL获得了室温连续输出功率为1.63 W,功率转换效率提高了6%.     

Edge-emitting semiconductor microlasers with ultrashort-cavity anddry-etched high-reflectivity photonic microstructure mirrors

We demonstrate very compact low-threshold edge-emitting semiconductor lasers operating at a wavelength of 980 nm, in which periodic microstructure mirrors have been formed at both cavity ends by deep reactive ion etching. From a threshold analysis, we determined reflectivities of ~95% for the seven-period back reflector and ~80% for the three-period front mirror. Lasing has been achieved from 20-μm-long and 8-μm-wide devices exhibiting a current threshold of 7 mA. These are among the shortest in-plane electrically pumped lasers demonstrated so far. State-of-the-art electron beam lithography (EEL) and high-aspect ratio reactive ion etching (RIE) have been used for device fabrication     

全光纤型Er/Yb共掺光纤短腔激光器

报道了一种高输出功率、高斜率效率的短腔ErYb共掺杂光纤激光器。激光谐振腔由一段ErYb共掺杂单模光纤与一对布拉格反射波长相同的光纤布拉格光栅(FBG)组成。反射率为60%的光纤光栅用作光纤激光器谐振腔的输出,3dB带宽为016nm。反射率为99%的光纤光栅作为高宽带反射腔镜,同时作为抽运光输入端,3dB带宽102nm。以980nm激光二极管(LD)作抽运源进行实验。使用不同的抽运功率分别测量不同长度的ErYb共掺杂光纤,优化光纤激光器谐振腔得到的最佳长度仅为13cm。即选用13cmErYb共掺杂光纤作为增益介质来制作短腔ErYb光纤光栅激光器,最大输出功率可达11mW,输出功率稳定性<±001dB,抽运阈值功率为35mW,斜率效率为153%,测量其15522nm激光的输出光谱,25dB线宽为03nm,边模抑制比>60dB,波长稳定性为005nm。可用于密集波分复用(DWDM)系统。     

半导体激光器输出光功率的最佳值

本文分析了半导体激光器输出光功率与镜面反射率的关系,数值计算结果表明镀制介质腔控制正反镜面反射率可以得到最佳输出光功率.此外,分析表明减少腔内损耗,减薄有源层厚度和缩小条宽对输出功率都有显著的增加.     

大功率半导体激光器腔面氮钝化的研究

针对980 nm大功率半导体激光器腔面离子铣氮钝化处理工艺进行了研究,发现腔面离子铣氮钝化可以提高激光器的输出特性及COD功率,器件输出功率提高了32.14%;老化实验后,经过氮钝化的半导体激光器没有明显退化,而未经氮钝化处理的激光器退化严重;使用俄歇谱测试仪(AES)对钝化处理后的半导体激光器试验片进行测试,发现有部分的氮离子遗留在腔面处;氮元素含量由原有的0%上升到20%,与此同时,氧元素的含量由原来的61%降至30%。结果表明,该技术能够改善半导体激光器的腔面特性,器件的可靠性和使用寿命可望得到提高。     

大功率半导体激光医疗机技术及应用展望

文中系统地介绍了大功率半导体激光医疗机的技术特点和应用前景，着重分析了国外产品的特点，大功率半导体激光医疗机与其他目前常用的大功率激光医疗机的优劣，比较了波长为８１０ｎｍ与波长为９８０ｎｍ的半导体激光机的性能，最后阐述了大功率半导体激光医疗机的技术要点。     

大功率小垂直发散角980nm量子阱激光器

提出了一种新型非对称宽耦合波导结构,通过理论计算优化了结构中n型波导层和限制层厚度,并采用低压金属有机化学气相沉积方法生长了设计的器件结构.测试了器件的光电特性,1200μm腔长器件的阈值电流为590 mA,斜率效率为0.96 w/A,最大输出功率达2000mW;当注入电流为0.6 A时,其远场发散角为16.1°(θ⊥)×10.2°(θ//).实验结果表明:新型非对称宽耦合波导结构能实现器件大功率输出,有效减小器件远场垂直发散角,改善器件光束质量.     

Analysis of reflectivity for a beveled corner mirror insemiconductor ring lasers

A semiconductor ring laser is expected to be used as a tiny ring laser gyro with low power consumption, which is suitable for mobile systems. However, its corner mirrors may be beveled due to its fabrication processes. Therefore, in this paper, reflectivities of beveled corner mirrors in the semiconductor ring laser are examined. In the analysis here, a guided fundamental mode is expanded into plane waves, and thus vertical confinement of the guided mode is completely incorporated. It is revealed that there is an optimum guiding layer thickness of approximately 0.3 μm to minimize mirror losses in the beveled mirrors. Also, facet reflectivities of equilateral n-polygon shaped ring lasers with beveled mirrors are studied, and it is found that a large n leads to a low threshold current     

Packaging and Performance of 980nm Broad Area Semiconductor Lasers

<正>High power broad area semiconductor lasers have found increasing applications in pumping of solid state laser systems and fiber amplifiers, frequency doubling, medical systems and material processing. Packaging including the assembly design, process and thermal management, has a significant impact on the optical performance and reliability of a high power broad area laser. In this paper, we introduce the package structures and assembling process of 980nm broad area lasers and report the performances including output power, thermal behavior and far fields.We will report two types of high power broad area laser assemblies. One is a microchannel liquid cooled assembly and the other is a conduction cooled CT-mount assembly .Optical powers of 15W and 10W were achieved from a 980nm broad area laser with a 120μm stripe width in a microchannel liquid cooled assembly and conduction cooled CT-mount assembly, respectively .Furthermore, a high power of 6.5 W out of fiber was demonstrated from a pigtailed, fully packaged butterfly-type module without TEC ( Thermoelectric cooler ).The measurement results showed that thermal management is the key in not only improving output power, but also significantly improving beam divergence and far field distribution. The results also showed that the die attach solder can significant impact the reliability of high power broad area lasers and that indium solder is not suitable for high power laser applications due to electromigration at high current densities and high temperatures.     

A scheme of picosecond pulse shaping using gain saturationcharacteristics of semiconductor laser amplifiers

To obtain high power, well shaped picosecond pulses from gain-switched semiconductor lasers, the use of dynamic gain saturation characteristics of semiconductor laser amplifiers was investigated theoretically and experimentally. A configuration of a reflected-wave amplifier (RWA) with single-side external coupling is introduced for pulse shaping, which is found to be suitable for enhancing dynamic gain saturation. By a combination of a distributed feedback laser oscillator at 1.3 μm in wavelength and a reflected-wave amplifier of 400 μm cavity length with asymmetric facet reflectivities of 0.01% and 30%, single-mode optical pulses with almost no tailing, full width at half maximum of 15 ps, and peak power exceeding 50 mW were obtained without pulse broadening, despite the considerable tail structure of the incident pulse     

Amplified spontaneous emission effects in semiconductor laseramplifiers

The analysis presented provides a quantitative method for predicting semiconductor laser amplifier performance in the presence of ASE (amplified spontaneous emission). It indicates that in order to increase the fraction of pump power that contributes to the amplification of the input laser field relative to that spent in overcoming internal losses, an amplifier should operate at as high an excitation level as possible. This may mean operating an amplifier above its free-running oscillation threshold. A limitation to the maximum pump power is the increase in ASE. With too high an excitation, ASE dominates over the amplified input laser field, resulting in a quenching of the amplifier gain, efficiency and coherence. ASE effects may be mitigated by increasing the input laser intensity, decreasing the amplifier facet reflectivities, or, in some cases, tuning the master oscillator so that it is resonant with the amplifier. The analysis indicates that minimizing the facet reflectivity is the most effective way to circumvent ASE limitations to power scaling semiconductor laser amplifiers