Fabrication and Characteristics of GaN-based Blue VCSEL

利用金属有机物气相沉积技术(MOCVD)在(0001)蓝宝石衬底上生长了Ga N基垂直腔面发射激光器(VCSEL)的多量子阱腔层结构。X射线衍射测量显示该多量子阱具有良好周期结构和平整界面。运用键合及激光剥离技术将该外延片制作成VCSEL,顶部和底部反射镜为极高反射率的介质膜分布布拉格反射镜(DBR)。在室温、紫外脉冲激光的泵浦条件下,观察到了VCSEL明显的激射现象,峰值波长位于447.7 nm,半高宽为0.11 nm,自发辐射因子约为6.0×10-2,阈值能量密度约为8.8 m J/cm2。在大幅度降低制作难度的情况下,得到目前国际最好结果同样数量级的激射阈值。降低器件制作难度有利于制备的重复性,有利于器件的产品化。Ga N-based multiple quantum wells( MQWs) were epitaxially grown on( 0001)-oriented sapphire substrate by metal organic chemical vapor deposition( MOCVD) technique. X-ray diffraction measurements indicated that the MQWs had good periodic structure and smooth interface. By employing bonding and laser lift-off techniques,the MQW structure was sandwiched between two high reflectivity dielectric distributed Bragg reflectors( DBRs),forming a vertical-cavity surfaceemitting laser( VCSEL). Under optical pumping,the VCSEL achieved laser action at room temperature with a threshold pumping energy density of about 8. 8 m J / cm2. The laser emitted a blue light at 447. 7 nm with a narrow linewidth of 0. 11 nm,and had a high spontaneous emission factor of about 6. 0 × 10- 2.国家自然科学基金(61307115);; 福建省教育厅A类科技项目(JA12249);; 厦门理工学院高校高层次人才基金(YKJ11026R);; 福建省自然科学基金(2013J05104)资助项

Influence of salinity and day and night rhythm on feeding rate(FR) of Ruditapes philippinarum

在实验室条件下 ,用流水系统测定盐度和昼夜节律对菲律宾蛤仔摄食率的影响 .分别对 1 5、2 0、2 5、3 0、3 5这 5个盐度梯度 ,以及连续 2 4h的 0 0 :0 0、0 4:0 0、0 8:0 0、1 2 :0 0、1 6:0 0、2 0 :0 0这 6个时间点下菲律宾蛤仔的摄食率进行了测定 .结果表明 :在1 5～ 2 5的盐度范围内 ,蛤仔的摄食率随着盐度的升高而增大 ,在盐度 2 5时达到最大 ,而在 2 5～ 3 5盐度范围内随盐度的增加而减小 ;在一个昼夜里 ,蛤仔的摄食率存在显著的差异 ,夜间的摄食率明显高于白昼 ,0 0 :0 0和 1 2 :0 0分别是两个极值 ;菲律宾蛤仔是一个有着明显昼夜节律性的底栖动物 ,并且对盐度有一个适应范围 ,盐度 2 5～ 3 0是其最适的盐度 .本实验为以后进一步研究菲律宾蛤仔在贝类混养虾池中的作用奠定了基础 .The FR of Ruditapes philippinarum was determined at salinity of 15‰,20‰,25‰,30‰,35‰ and 00:00,04:00,08:00,12:00,16:00,20:00, in consecutive 24 hours. The results showed that the FR of Ruditapes was significantly high at salinity of 25‰ to 30‰,low at other salinity. Difference also showed in the experiments of day and night rhythm. The FR in mid-night(24:00) was extreme high and mid-noon's(12:00) FR was the lowest. It appeared that Ruditapes philippinarum is a species of mollusk with day and night rhythm feeding behavior. That salinity of 25‰ to 30‰ was suitable to Ruditapes philippinarum's can also be concluded. This work will do good for further research to make clear what role Ruditapes philippinarum played in composite-cultivating shrimp-ponds.福建省“重中之重”基金项