Development of Novel Distributed Feedback Semiconductor Lasers with Reflection Insensitivity and Very Low Chirping Property

1.一种新颖的分布反馈（DFB）激光器结构已被提出，其中原则上产生纯增益耦合而没有折射率耦合。我们利用有机金属气相外延的特殊生长动力学实现了它，并实现了室温连续工作，阈值电流为17 mA。我们还从理论和实验上证明，在增益耦合DFB激光器中，振荡模式是唯一定义的，与端面相位无关，因此即使在解理端面也能获得很高的单模产率.增益耦合DFB激光器的外反射不灵敏度测量了这种激光器的强度噪声对外反射的依赖性，并与常规DFB激光器的强度噪声进行了比较。当反射量小于1%时，远距离反射引起的多余噪声减少10- 20 dB，而远距离反射引起的多余噪声几乎不增加 ...更多信息 在相邻反射的情况下观察到噪声中的e.增益耦合DFB激光器中超低啁啾、单模光短脉冲的产生我们在上述激光器中进行了利用电脉冲产生增益开关短光脉冲的实验，获得了16 ps半高宽的光脉冲。测量了光脉冲的时间平均谱，发现其为单模，半高宽为0.12nm。从这些值估计的线宽增强因子小至1.6.4。具有分布电极和调制条宽结构的低啁啾DFB激光器通过数值模拟表明，采用上述结构，可以完全消除纵向空间烧孔引起的振荡波长漂移，并可以显著减小弛豫振荡所伴随的啁啾.用于低啁啾操作的DFB激光器和调制器/放大器的单片集成已经尝试了通过集成行波光放大器/调制器来实现低啁啾调制的替代方法。我们指出了反应离子刻蚀形成的角度的小平面的有用性，以减少光学串扰。该集成器件的阈值电流为20 mA，光增益为10 dB，具有良好的实用价值。少

1. Purely Gain-Coupled Distributed Feedback (DFB) Laser A novel DFB laser structure has been proposed, where pure gain coupling without index coupling is in principle brought about. We realized it by utilizing a special growth kinetics of organo-metallic vapor phase epitaxy, and achieved room-temperature continuous-wave operation with very low threshold current of 17mA. We have also showed theoretically and experimentally that, in the gain-coupled DFB laser, the oscillation mode is uniquely defined irrespective of facet phases, and there fore that very high single mode yield is obtainable even with as-cleaved end facets.2. External Reflection Insensitivity in Gain-Coupled DFB Lasers Dependence of intensity noise on external reflection of the above laser has been measured and compared with that of the conventional DFB laser. If the amount of reflection was less than 1%, the excess noise induced by the reflection was 10-20dB less in the case of remote reflection, and virtually no increas … More e in noise was observed in the case of adjacent reflection.3. Ultralow Chirping, Single Mode Optical Short Pulse Generation in Gain-Coupled DFB Lasers We have tried gain-switching short optical pulse generation experiment in the above laser using electrical pulses, and obtained an optical pulse of 16ps FWHM. Time-averaged spectra of the optical pulse have been measured and surprisingly found to be of single mode with 0.12nm FWHM. The linewidth enhancement factor estimated from these values is as small as 1.6.4. Low Chirping DFB Lasers with Distributed Electrode and Modulated Stripe Width Structures It has been shown through numerical simulation that, by using the above structures proposed here, the oscillation wavelength shift resulting from the longitudinal spatial hole burning can completely be eliminated, and that the chirping accompanying the relaxation oscillation can considerably be reduced.5. Monolithic Integration of a DFB Laser and a Modulator / Amplifier for Low Chirping Operation An alternative approach to realize low chirping modulation has been tried by integrating a traveling wave optical amplifier / modulator. We pointed out the usefulness of angled facets formed by reactive ion etching for reduction of optical cross-talk. The fabricated integrated device exhibited performances good enough for practical use, such as 20mA threshold and 10dB optical gain. Less