半导体激光器单管准直实验研究

利用高斯光束的ABCD传输矩阵理论分析了LD与自聚焦透镜之间的距离与出射光束远场光斑尺寸之间的关系.通过理论计算可以方便地得到最佳距离,获得较高亮度输出,并进行了实验验证.对平面自聚焦透镜、球面自聚焦透镜和圆柱透镜的准直效果进行了实验比较,最后将自聚焦透镜与LD固定,制做了实用的器件,该器件可以将LD椭圆形光斑转变成线形光斑,快轴、慢轴远场发散角分别为0.1°和2.50°耦合效率86%.     

大功率宽条分布反馈激光器研究

大功率半导体激光器一般用作抽运源,但其抽运的离子吸收峰带宽一般都比较小。为提高大功率半导体激光器对固体或光纤激光器等的抽运效率,就要降低半导体激光器的输出波长随注入电流和热沉温度的漂移系数。分析了光栅深度和光栅填充因子对激光器输出波长锁定效果的影响,实验验证确定出合适的光栅参数,依据优化条件得出合适的激光器腔长,制备出锁定效果良好的宽条分布反馈激光器。该激光器的单管腔长2.4mm,发光条宽100μm,连续最大输出功率400mW,热沉温度为15℃时的输出波长为954nm,输出波长随注入电流的漂移系数为0.67nm/A,输出波长的温漂系数为0.046nm/K。     

259W准连续无铝808nm激光二极管线列阵

通过优化张应变量子阱外延结构和设计线列阵双沟道深隔离槽腐蚀工艺,采用低压金属有机化学气相沉积法（LP-MOCVD）生长了GaAsP/GaInP/AlGaInP单量子阱分别限制异质结激光器材料,并利用该材料制备了填充因子为50%的1cm宽线列阵激光巴条,用扫描电子显微镜（SEM）分析了隔离槽的形貌. 在准连续工作条件（200μs脉宽,2%占空比）下,封装在被动制冷标准铜热沉上的器件在测试设备允许的最大驱动电流300A时可获得259W的输出功率,未观察到腔面光学灾变性损伤的发生. 最高功率转换效率在工作电流为104A时达52%, 此时输出功率为100W,激射光谱的中心波长为807.8nm,半高宽为2.4nm,快慢轴远场发散角分别为29.3°和7.5°.     

新型激光二极管列阵光束整形方法

设计并制作了一套简单有效的光束整形系统,用以改善激光二极管列阵器件(LDA)的光束质量,减小快慢轴光束质量积的差别,实现高亮度光纤耦合输出。首先采用快慢轴准直透镜压缩LDA的发散角,然后采用双面分区镀膜的单片平面镜,通过反射和折射将压缩后的LDA慢轴方向的光束分为7束,并将7束子光束在快轴方向重新排列,实验测得整形装置的效率为95.2%。该整形系统设计简单,效率高,具有很高的应用价值。     

实用化1730nm波段掩埋结构半导体激光器的研制

报道了应用于医疗器械的InP基1730nm波段半导体激光器.外延片采用低压金属有机物化学气相沉积法(MOCVD)生长,有源区为5个周期的InGaAs量子阱层和InGaAsP垒层.器件采用pnpn结限制掩埋结构,有源区脊宽2μm、腔长300μm.室温下腔面镀膜后激光器管芯的阈值电流为18±5mA,8mW输出功率时的工作电流为60±5mA.采用TO封装后,100mA工作电流下激光器的输出功率大于5mW,输出波长为1732±10nm,高温恒流加速老化筛选实验表明,器件具有长期工作的可靠性,满足实用化要求.     

双平行平面反射镜在激光二极管阵列光束整形中的应用

为了实现激光二极管阵列(LDA)的高亮度光纤耦合输出,设计了一套简单有效的光束整形系统.首先采用快慢轴准直透镜压缩LDA的发散角,然后采用双平行平面反射镜光束整形装置,将压缩后的LDA慢轴方向的光束分为4束(也可以根据需要分为任意多束),并将4束子光束在快轴方向重新排列,最后通过聚焦系统,将整形后的光束耦合进入芯径600 μm,数值孔径0.37的光纤.实验测得双平行平面反射镜整形装置的效率为98.87%,系统的整体效率为77.2%.该整形系统设计简单,效牢高,具有很高的应用价值.     

An asymmetric broad waveguide structure for a 0.98-μm high-conversion-efficiency diode laser

A novel asymmetric broad waveguide diode laser structure was designed for high power conversion efficiency（PCE）.The internal quantum efficiency,the series resistance,and the thermal resistance were theoretically optimized.The series resistance and the thermal resistance were greatly decreased by optimizing the thickness of the P-waveguide and the P-cladding layers.The internal quantum efficiency was increased by introducing a novel strain-compensated GaAs0.9P0.1/InGaAs quantum well.Experimentally,a single 1-cm bar with 20% fill factor and 900 μm cavity length was mounted P-side down on a microchannel-cooled heatsink,and a peak PCE of 60% is obtained at 26.3-W continuous wave output power.The results prove that this novel asymmetric waveguide structure design is an efficient approach to improve the PCE.     

Thermal investigation of high-power GaAs-based laser diodes

The thermal characteristics of high-power AlGaAs/GaAs laser diodes (LDs) at high current (2-10 A) are studied with electrical transient method. The temperature rise increases linearly with the current. The thermal resistance of chip is the largest proportion of total thermal resistance. By increasing the width of the chip from 500 to 800 μm, the temperature rise and thermal resistance decrease by 8.5% and 8.8%, respectively.     

A Hybrid Catalytic Conversion of Corncob to Furfurylamine in Tandem Reaction with Aluminium-Based Alkaline-Treated Graphite and ω-Transaminase Biocatalyst in γ-Valerolactone–Water

Furfurylamine is an important furfural-upgrading biobased chemical for the production of pharmaceuticals, biofuels, fibers, additives, polymers, etc. In one-pot reaction system, biomass was tandemly catalyzed to furfurylamine with aluminium-based alkaline-treated graphite (Al-AG) catalyst and recombinant ω-transaminase biocatalyst. Al-AG (3.6 wt%) catalyzed corncob (75.0 g/L) to 110.0 mM furfural at 56.8% yield (based on xylan in corncob) in γ-valerolactone–water (1:4, v:v; pH 1.0) for 40 min at 180 °C. The pH-adjusted corncob-slurry (pH 7.5) containing furfural were catalyzed to furfurylamine at high yield with γ-valerolactone-tolerant Aspergillus terreus ω-transaminase biocatalyst at 35 °C using isopropylamine (3 mol isopropylamine/mol furfural) as amine donor. Such an efficient and sustainable approach for catalytic conversion of biomass to high-value-added biobased furfurylamine was successfully established in tandem reaction with Al-AG and ω-transaminase biocatalyst.

Graphic Abstract

     

大功率低阈值980nm单模AlGaInAs/AlGaAs量子阱激光器

To achieve low threshold current as well as high single mode output power,a graded index separate confinement heterostructure(GRIN-SCH)AlGaInAs/AlGaAs quantum well laser with an optimized ridge waveguide was fabricated.The threshold current was reduced to 8 mA.An output power of 76 mW was achieved at100 mA current at room temperature,with a slope efficiency of 0.83 W/A and a horizon divergent angle of 6.3.The maximum single mode output power of the device reached as high as 450 mW.