基于氮化镓非对称耦合量子阱隧穿效应的超短激光脉冲发射

As a kind of very important blue-pulse light source, Gallium nitride (GaN) based blue pulse lasers have many potential applications in both military and civilian purposes, wherein, understanding the fundamentals of gain-switching and decreasing the output pulse width down to picoseconds that satisfy the requirement of proper applications are of critical importance. Based on previous studies, the applicant propose to control the transient gain in active layers and therefore the gain-switching properties of semiconductor lasers by carrier tunneling in asymmetric coupled quantum wells: (1) The applicant will first design and fabricate some wafers and ridge-waveguide lasers based on InGaN asymmetric coupled quantum wells, and try to control the carrier tunneling by optimizing the structures of quantum wells and the sub-band energy levels. (2) Through the ultra-fast time-resolved spectroscopy and other advanced experimental setups, the carrier dynamics including tunneling and recombination, and the gain-switching characteristics of the lasers will be systematically investigated. (3) In combination with theoretical analysis, the applicant will try to find the relations between the structures of quantum wells and laser cavity, carrier tunneling, and gain-switched pulse characteristics, and will have an in-depth understanding of the fundamentals of the new technique in controlling the gain-switching characteristics by carrier tunneling via optimization of the InGaN/GaN quantum well structures. This project is expected to be useful not only for in-depth understanding of the fundamentals of carrier tunneling dynamics but also for fabricating GaN-coupled-quantum-well based lasers with picosecond ultrashort blue pulses, and therefore to be of importance for both fundamentals and applications.

氮化镓基脉冲激光器是一种重要的蓝光脉冲光源，在军民领域有着广泛应用。深入理解氮化镓脉冲激光器瞬态增益开关物理机制，并缩短其脉冲宽度至皮秒级别，对促进其发展和应用至关重要。本项目基于已有基础，利用耦合量子阱间载流子隧穿来调控激光器增益及其瞬态脉冲输出特性,进而获得超短脉冲:1.设计并制备氮化镓非对称耦合量子阱结构及里脊波导型激光器，通过优化量子阱及其子能级结构来控制阱间载流子隧穿；2.利用超快时间分辨光谱等先进表征手段，系统研究不同结构量子阱的载流子隧穿与复合物理机制以及激光器增益开关脉冲特性；3.结合理论分析，建立“量子阱及激光器结构-载流子隧穿-激光脉冲”之间的关系，探索通过优化氮化镓激光器非对称耦合量子阱结构来控制载流子隧穿进而获得超短激光脉冲的新方法及其物理机制。本研究不仅有助于深入理解量子阱载流子隧穿的相关基础问题，还可能研制出皮秒级别氮化镓超短蓝光脉冲激光器，具有理论和实用意义。

氮化镓激光器作为一种重要的蓝光光源，在工业加工、生物医疗、光通信、光传感等诸多领域展现出越来越多的应用前景。深入理解氮化镓脉冲激光器瞬态增益开关物理机制，研制半导体超短脉冲激光器，并缩短其脉冲宽度至皮秒级别，对促进其发展和应用至关重要。本项目提出并通过实验和理论研究，验证了可以利用有源区耦合量子阱间载流子隧穿来调控激光器增益及其瞬态脉冲输出特性,进而获得超短脉冲。项目的主要研究内容和成果总结如下:1.设计并制备GaAs和GaN非对称耦合量子阱外延片，以及GaN垂直腔面发射（VCSEL）和里脊波导型边发射激光器，验证了可以通过优化量子阱及其子能级结构来控制阱间载流子隧穿，进而影响脉冲激光输出特性；2.构建了超快时间分辨光谱等实验表征系统，详细研究了GaAs和GaN耦合以及非耦合量子阱的载流子隧穿与复合物理机制以及GaN垂直腔面发射和边发射激光器增益开关脉冲特性；3.构建了耦合量子阱以及半导体激光器理论分析，结合实验结果，研究了通过优化氮化镓激光器非对称耦合量子阱结构来控制载流子隧穿进而获得超短激光脉冲的物理机制。通过本项目的资助，发表SCI论文27篇，6篇入选期刊封面论文，培养硕士和博士生19人，申请国家发明专利16项，获得科技奖励4项。本研究不仅有助于深入理解量子阱载流子隧穿的相关基础问题，对进一步研制出皮秒级别氮化镓超短蓝光脉冲激光器，具有重要的理论和实验指导意义。