Development of ultrahigh performance semiconductor lasers for photonic information infrastructure

1.吸收光栅增益耦合（GC）分布反馈（DFB）激光器的研制我们研制了基于吸收光栅结构的1.55 μ m波段GC DFB激光器。采用压应变InGaAsP多量子阱作为有源层，InGaAs作为吸收光栅层。该器件在室温下连续工作，阈值电流为20- 30 mA，在端面未镀膜的情况下，获得了边模抑制为40- 55 dB的高产率单模激光输出。2.抗外反射性能的表征对上述激光器的抗外反射性能进行了表征。随着增益耦合系数的增加，它们的临界反馈电平也随之提高。3.波长微调我们提出了波分复用光通信系统中的“波长微调”概念，并研究了其实现方法。首先，利用光致折射率ch 关于我们 尝试在硫系玻璃中添加硫系元素，并开发了一种沿DFB激光器有源层加载硫系元素的新结构。用He-Ne激光束照射，在1.55 μ m处实现了0.14nm波长的微调。其次，尝试了基于光吸收诱导量子威尔斯无序的波长微调，并利用YAG激光器实现了0.36nm的波长微调。4. GC DFB激光三极管的制作首次采用四步金属有机气相外延（MOVPE）工艺成功地制作了GC DFB激光三极管。实验上证明了吸收光栅中吸收系数的变化以及在第三端施加电压时耦合系数的变化。5.模拟调制失真的分析与测量用一种新的数值方法分析了吸收光栅型GC DFB激光器的模拟调制失真。结果发现，由于光栅中的吸收压缩抵消了有源层中的增益压缩，二次谐波失真得以减小。6.具有量子线有源区的GCDFB激光器的研制利用V型槽衬底上的MOVPE生长技术，首次成功地研制出了具有InGaAs应变量子线有源区的GCDFB激光器。少

1.Development of absorptive-grating gain-coupled (GC) distributed-feedback (DFB) lasersWe fabricated and developed 1.55mum wavelength band GC DFB lasers based on absorptive grating structure. A compressively strained InGaAsP multiple quantum well was used as an active layr, and InGaAs was used as the absorptive grating layr. The device operated at room temperature in CW with threshold current of 20-30mA.We achieved high-yield single-mode lasing with 40-55dB side mode suppression without applying antireflection coating on the facets.2.Characterization of external reflection immunityExternal reflection immunity of the above lasers was characterized. Their critical feedback level was found to be improved with increasing gain coupling coefficient.3.Wavelength trimmingWe proposed "wavelength trimming", a new concept toward wavelength division multiplexed optical communication systems, and investigated its realization. First, the wavelength trimming utilizing Photoinduced refractive index ch … More ange in chalcogenide glasses was tried, and developed a new structure where the chalcogenide was loaded alongside the DFB laser active layr. By irradiating He-Ne laser beam, we demonstrated 0.14nm wavelength trimming at 1.55mum. Next, the wavelength trimming based on photo-absorption-induced disordering of quantum wells was tried, and 0.36nm trimming was accomplished by YAG laser irradiation.4.Fabrication of GC DFB laser triodeGC DFB laser triodes have successfully been fabricated for the first time by four step metal organic vapor phase epitaxy (MOVPE). Changes of absorption coefficient in the absorptive grating and of the coupling coefficients by applying voltage to the third terminal have experimentally been demonstrated.5.Analysis and measurement of analog modulation distortionWe analyzed analog modulation distortion in GC DFB lasers of absorptive grating type by a newly-developed numerical method. As a result, the second harmonic distortion was found to be reduced due to cancellation of gain compression in the active layr by absorption compression in the grating. A preliminary experiment was conducted to confirm the above theoretical prediction.6.Fabrication of a GC DFB laser with quantum wire active regionBy making use of MOVPE growth on V-grooved substrates, a GC DFB laser with InGaAs strained quantum wire active region has successfully been fabricated for the first time. Less