Single-mode low threshold current multi-hole vertical-cavity surface-emitting lasers

A multi-hole vertical-cavity surface-emitting laser(VCSEL) operating in stable single mode with a low threshold current was produced by introducing multi-leaf scallop holes on the top distributed Bragg-reflector of an oxidationconfined 850 nm VCSEL.The single-mode output power of 2.6 mW,threshold current of 0.6 mA,full width of half maximum lasing spectrum of less than 0.1 nm,side mode suppression ratio of 28.4 dB,and far-field divergence angle of about 10 are obtained.The effects of different hole depths on the optical characteristics are simulated and analysed,including far-field divergence,spectrum and lateral cavity mode.The single-mode performance of this multi-hole device is attributed to the large radiation loss from the inter-hole spacing and the scattering loss at the bottom of the holes,particularly for higher order modes.     

氧化孔形状对光子晶体垂直腔面发射激光器模式的影响

用时域有限差分方法对氧化孔限制型外腔式光子晶体垂直腔面发射激光器 (VCSEL) 在小氧化孔下氧化孔形状对激光器模式特性的影响进行了模拟计算. 建立了三维光子晶体面发射激光器光场计算模型, 分析了氧化孔形状变化对器件远场特性与频率特性的影响. 研究发现, 氧化孔形状可影响光子晶体VCSEL的模式特性, 尤其是频谱特性. 从模场分布的角度可解释为菱形氧化孔的对称性与高阶模的不一致. 但随着光子晶体刻蚀深度的增加和氧化孔的增大, 这种影响逐渐减小, 分析解释了其原因. 研究结果为提高光子晶体面发射激光器的性能提供了参考.     

光子晶体垂直腔面发射激光器的电流分布研究

对氧化限制型外腔式光子晶体垂直腔面发射激光器注入到有源区的电流密度分布进行了分析研究.提出三维电流分布计算模型,研究了光子晶体结构对电流密度分布和器件串联电阻的影响.研究发现,光子晶体孔刻蚀深度越深,电流分布圆对称性越差,引起的串联电阻越大.不同光子晶体图案对电流分布的均匀性和圆对称性也有很大的影响.该模型对于研究、设计氧化限制型外腔式光子晶体垂直腔面发射激光器提供了一个有用的分析方法.     

A Chiron-based Approach for the Synthesis of Tricyclic Tyrosine Analogue

A chiron approach-based enantioselective synthesis of designed tricyclic tyrosine analogue D-2 was developed. A SmI2-mediated free radical cyclization, an intramolecular Friedel-Crafts reaction and an intramolecular Mannich reaction served as key steps. These key steps were optimized and repeated in good yields. All the stereochemistries in the synthesis were established and confirmed.     

Single-mode low threshold current multi-hole vertical-cavity surface-emitting lasers

A multi-hole vertical-cavity surface-emitting laser (VCSEL) operating in stable single mode with a low threshold current was produced by introducing multi-leaf scallop holes on the top distributed Bragg-reflector of an oxidation-confined 850 nm VCSEL. The single-mode output power of 2.6 mW, threshold current of 0.6 mA, full width of half maximum lasing spectrum of less than 0.1 nm, side mode suppression ratio of 28.4 dB, and far-field divergence angle of about 10° are obtained. The effects of different hole depths on the optical characteristics are simulated and analysed, including far-field divergence, spectrum and lateral cavity mode. The single-mode performance of this multi-hole device is attributed to the large radiation loss from the inter-hole spacing and the scattering loss at the bottom of the holes, particularly for higher order modes.