Research of a hig-performance dynamic-single-mode laser

本研究的主要目的是从理论和实验上阐明高速直接调制下的动态单模激光器的动态特性，从而实现高性能的分布布拉格反射器(DBR)动态单模激光器。为了达到这一目的，我们发明了一种新的波导耦合结构，称为束集成波导(BIG)，它使我们能够在DBR激光器的有源和无源波导区之间获得非常高的耦合效率，并且在制作过程中具有很高的重复性。我们从理论上指出，通过缩短DBR-DSM激光器的有源区长度，可以获得较低的阈值电流、较高的边模抑制比和较宽的单模工作温度范围等优良的激光性能。我们还从大DBR-DSM激光器的激光特性上证明了这一点。我们测量了…用双模速率方程描述了BIG-DBR-DSM激光器在高速直接调制下的波长抖动和边模抑制比等动态特性，从理论上分析了DBR激光器的谱线宽及其与腔体结构的关系，结果与实验结果吻合较好。为了提高BIG-DBR激光器的重复性，以获得更高的激光性能，提出了一种岛式图案刻蚀和选择性再生的新工艺，获得了12.4 mW的高输出功率和38dB以上的高边模抑制比。此外，还提出了一种新颖的分布反射面(DR)激光器，实现了阈值电流低、输出功率高、单模运转性能优良的特性。较少

The main purpose of this research is to realize high-performance dhnamicsingle-mode (DSM) lasers with distributed Bragg reflectors (DBR) by clarifying the dynamic propertis under a high-speed direct modulation both theoretically and experimentally. In order to achieve this purpose, we invented a new waveguide coupling structure called Bundle-Integrated-Guide (BIG), which enables us to attain very high coupling efficiency between the active and the passive waveguide regions in DBR laser and also high reproducibility in its fabrication process. Specific results obtained in this research are summatized as follow.We theoretially pointed out that superior lasing properties, such as a lower threshold current, a higher side-mode suppression ratio, and a wider temperature range for a fixed-single-mode operation, would be obrained by shortening the active region length of DBR-DSM lasers and we also proved that experimentally from the lasing properties of BIG-DBR-DSM lasers.We measured the spect … More ral behaviour of the BIG-DBR-DSM laser under a highspeed direct modulation, such as wavelength chitping and the side-mode-suppression ratio during the modulation period, and clarified these dyanmic properties in terms of 2-mode rate equations.Spectral linewidht of DBR laser and its dependence on the cavity structure was theoretically analized and the result was found to be in good agreement with experimental results obtained for BIG-DBR-DSM lasers. Quite a narrow linewidht of 6.5MHz was obtained at the bias level of 2.2 times the thershold.To improve the reproducibility of BIG-DBR lasers ans to obtain higher lasing performances, a new fabrication process using an island-type pattern etching ans selective regowth was proposed and much improvement was obtained such as high output power of 12.4mW and high side-mode suppression ratio larger than 38dB. Moreover, a novel distributed reflector (DR) laser was proposed to achieve lower threshold current and higher output power operation, and was realized with superior single-mode operation properties. Less