Development of DFB Lasers with New Structures for Complete Single-Longitudinal-Mode Oscillation

作为开发具有调制条纹宽度结构的0.8 <mu> m范围分布反馈（DFB）激光器的第一步，首席研究员和同事于1985学年制作和研究了GaAlAs/GaAs脊波导DFB激光器，并实现了当时最低阈值电流和高差分量子效率。由此表明了在短波长范围内获得可行的DFB激光器的可能性，但从精确的横向模式分析中发现，这种波导结构不一定有利于液相外延（LPE）。1986学年，双通道平面埋置异质结构作为一种更适合LPE的波导结构，首次被用于制备GaAlAs/GaAs DFB激光器。在所得到的器件中获得了显著的特性改进，例如阈值电流为12mA，这是有史以来最低的。然后，将各种条纹宽度调制方案应用于发展中国家的器件，在实践中实现了完全的单纵向=模（SLM）振荡，与理论预测一致。神谷研究员研究了半导体激光器的材料物理学，以实现其功能的另一种演变。他利用相移法确定了半导体中的载流子寿命和复合系数。讨论了俄歇复合对半导体激光器双稳态特性温度依赖性的影响。这些研究有助于获得描述半导体激光器的详细速率方程，并获得更高的材料参数精度。研究人员Nagai检查SLM操作的DFB激光器通过两个面劈裂结构。他从理论上和实验上讨论了1.3和1.5 <mu> m的劈裂面器件的SLM概率和SLM工作的温度范围，从而有助于澄清劈裂面结构的有效性。研究者秋叶通过四分之一波移结构研究了SLM振荡。通过对1.5 μ > m范围四分之一波移器件的详细理论考察和实验观察，建立了该激光器的设计原理和制造技术，为该激光器的实际应用做出了贡献。少

As a primary step to develop 0.8 <mu> m range distributed feedback (DFB) lasers with modulated stripe width structure, the head investigator and coworkers fabricated and studied GaAlAs/GaAs ridge waveguide DFB lasers in 1985 academic year and achieved the lowest threshold current and high differential quantum efficiency at that time. Possibility of obtaining feasible DFB lasers in the short wavelength regime was thereby shown, yet it was found from a precise lateral mode analysis that this waveguide structure is not necessarily favorable to liquid phase epitaxy (LPE). In 1986 academic year, double channel planar buried heterostructure was instead employed in fabricating GaAlAs/GaAs DFB lasers for the first time, as a more appropriate waveguide structure for LPE. Significant improvements in characteristics were attained in the resulting devices, such as threshold current of 12mA which was the lowerst ever reported. Various stripe width modulation schemes were then applied to the develop … More ed devices, where complete single-longitudinal= mode (SLM) oscillation was in practice accomplished, being consistent with theoretical predictions.Investigator Kamiya studied material physics of semiconductor lasers toward another evolution of their functions. He determined carrier lifetime and recombination coefficients in semiconductors making use of a phase shift method. The effects of Auger recombination on temperature dependence of bistable characteristics in semiconducor lasers were also discussed. These studies contributed to obtaining detailed rate equations describing semiconductor lasers, and acquiring increased accuracy in material parameters.Investigator Nagai examined SLM operation of DFB lasers by means of both facets cleaved structure. He discussed theoretically and experimentally SLM probability and temperature range of SLM operation in 1.3 and 1.5 <mu> m devices with cleaved facets, thus contributing to clarification of the effectiveness of the cleaved facet structure.Investigator Akiba studied SLM oscillation by quarter-wave-shifted structure. Through detailed theoretical examination and experimental observation of 1.5 <mu> m range quarter-wave-shifted devices, he established design principles and fabrication techniques, thereby contributed toward practical applications of such lasers. Less