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）激光器的研制基于吸收光栅结构的1.55 μ m波段GC - DFB激光器。采用压缩应变InGaAsP多量子阱作为有源层，InGaAs作为吸收光栅层。该装置在室温连续工作，阈值电流为20-30mA。我们实现了40-55dB侧模抑制的高产单模激光，而无需在表面上应用增透涂层。外反射抗扰度表征对上述激光器的外反射抗扰度进行了表征。结果表明，随着增益耦合系数的增大，临界反馈水平得到提高。波长微调提出了波分复用光通信系统的新概念“波长微调”，并对其实现进行了研究。首先，利用光致折射率对硫系玻璃进行波长微调，并在DFB激光有源层旁边加载了硫系玻璃。通过辐照He-Ne激光束，我们在1.55mum下实现了0.14nm波长的微调。接下来，尝试了基于光吸收诱导量子阱无序化的波长微调，并通过YAG激光照射完成了0.36nm的波长微调。采用四步金属有机气相外延（MOVPE）技术首次成功制备了GC - DFB激光三极管。实验证明了在第三端施加电压对吸收光栅的吸收系数和耦合系数的影响。模拟调制失真的分析与测量采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，从而降低了二次谐波失真。通过初步实验验证了上述理论预测。利用MOVPE生长在v型沟槽衬底上，首次成功制备了InGaAs应变量子线有源的GC - DFB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