Development of High Performance Distributed Feedback Semiconductor Lasers for Short Wavelength Region

1.调制条带结构的DFB激光器我们将这种调制条带结构应用于短波长区域分布反馈(DFB)激光器，实现了其完全的单纵模振荡。这种结构是通过采用一种新的用于复合半导体的反应离子刻蚀(RIE)技术来实现的。同时介绍了几种制作衍射栅的新技术，包括利用RIE将光栅图案转移到外延层上。结果，极大地改善了光栅的齿形。据我们所知，这种器件是第一个在没有湿法刻蚀的情况下完成的掩埋异质结DFB激光器。其次，为了研究纵向空间烧孔对这种相移DFB激光器特性的准确影响，我们开发了一种精确的器件模拟器。根据计算结果，我们设计了适当的条带形状来降低…使这种影响最小化的结果是更多的波长啁啾。可见光DFB激光器根据我们已经开发出高性能0.88m DFB激光器的经验，我们接下来尝试进一步减少振荡波长。通过修改和改进制备工艺，我们成功地在我们的简单氧化物条形器件中获得了可见光区(Ibdabar.=770 nm)的DFB振荡。振荡波长与温度的关系为0.054 nm/K，在50K以上的温度范围内没有观察到跳模现象。具有增益耦合机制的DFB激光器我们首次将增益耦合机制引入到半导体DFB激光器中，并展示了它对完全单纵模振荡的有效性。我们还发现，这种DFB激光器的激光特性几乎不受小面反射的影响，这与传统的DFB激光器形成了鲜明的对比。这一功能是人们热切要求但从未实现的。DFB激光器与光调制器/放大器的单片集成研究了0.88m DFB激光器与光调制器/放大器的单片集成。由于在这种类型的集成器件中，元件之间的光学隔离是至关重要的，我们首先通过对振荡和调制特性进行数值分析来估计前端的最大可容忍反射率。已经完成了原型装置的制造。较少

1.DFB Laser with Modulated Stripe Width structure We applied the modulated stripe width structure to short wavelength region distributed feedback (DFB) lasers for achieving complete single longitudinal mode oscillation in them. This structure was made possible by employing a novel reactive ion etching (RIE) technigue for composite xemiconductors. At the same time several new techniques were introduced for the fabrication of diffraction grationgs, including the use of RIE for transferring the grating patterns onto the epitaxial layers. AS a result the tooth shape of the grating was greatly improved. To our knowledge the device thus fabricated was the first buried heterostructure DFB laser completed without wet etching. Next we developed an accurate device simulator in order to investigate the exact effect of longitudinal spatial hole burning on the characteristics of this kind of phase-shifted DFB laser. From the calculated results we designed appropriate stripe shapes for reducing the … More wavelength chirping as a consequence of minimizing that effect.2. Visible Light DFB Laser On our experience of having developed high performance 0.88 m DFB lasers, we next tried further reduction of oscillation wavelength. By modifying and improving the fabrication processes, we succeeded in obtaining DFB oscillation in visible wavelength region(【.Ibdabar.】=770nm) in our simple oxide stripe devices. Temperature dependence of oscillation wavelength was 0.054nm/K, and mode hopping was not observed within temperature range over 50K.3. DFB Laser with Gain Coupling Mechanism We for the first time introduced the gain coupling mechanism to the semiconductor DFB laser, and showed its usefulness for complete single longitudinal mode oscillation. We also found out that the lasing characteristics of a DFB laser of this kind are almost immune to facet reflection, which made a striking contrast with the conventional DFB lasers. This feature is the one that has been eagerly demanded but never realized.4. DFB Laser monolithically integrated with Optical Modulator/Amplifier Monolithic integration of a 0.88 m DFB laser and an optical modulator/amplifier was examined. Since, in integrated devices of this sort, optical isolation between element devices is essentially important, we first estimated the maxinum tolerable reflectivity at the front facet by carrying out numerical analysis of the osdillation and modulation characteristics. Fabrication of a prototype device has been completed. Less