An Antimonide Strained Quantum Well Laser Operating at Lambda > Micrometer

该小型企业创新研究第一阶段项目将证明通过MBE开发激光二极管的可行性，使用InGaAsSb/AlGaAsSb应变量子阱（QW）结构在中红外（MIR）范围（6？m）内工作。我们的MIR激光器结构的开发服务于各种双重用途的应用，直接用于分子光谱学，遥感，以及光纤电信和激光雷达系统。发射波长可扩展到6-m范围。结构材料工业公司的激光二极管由三个区域构成。中间是有源区，其中未掺杂的AlGaAsSb层限制了InGaAsSb量子阱。有源区被夹在两个重掺杂的AlGaAsSb包覆层，形成一个pn结，并提供光学限制。在阶段1中，激光器结构将生长具有缓冲层的InP衬底，AlGaAsSb层与缓冲层晶格匹配。对于锑化物，使用具有缓冲层的InP衬底已经证明优于GaSb和InAs。与传统的基于锑化物的QW或双异质结构（DH）激光器相比，他们预期通过使用应变QW结构来大幅增加激光波长。与量子效应相关的量子阱中态密度的修改可以导致更低的阈值电流和降低的温度灵敏度。他们将研究应变和量子效应以及俄歇复合过程，这是低带隙材料中的一种重要的非辐射机制，以优化其激光器设计。在第一阶段，他们的设计将得到实施，特点和比较模型。第一阶段的工作将为第二阶段的进一步发展奠定坚实的基础。所选择的应变量子阱方法将使他们能够开发这种材料，以覆盖后期阶段的激光波长范围从6到10 μ m。在第二阶段，将改进生长、加工和封装能力，并实施分布式反馈机制，以提高单模操作的模式选择性，从而生产出适合军事和商业应用的激光器。他们还将在红外光谱痕量气体浓度监测和分析系统中使用激光器。

This Small Business Innovation Research Phase I project will demonstrate feasibility of development of laser diodes by MBE, operating in the mid-infrared (MIR) range ((6ªm) using the InGaAsSb/AlGaAsSb strained quantum well (QW) structure. The development of our MIR laser structures serves a variety of dual-use applications having immediate use in molecular spectroscopy, remote sensing, as well as in optical fiber telecommunications and laser radar systems. The emitting wavelengths are extendible to cover the 6-ªm range. Structured Materials Industries, Inc.'s laser diode is constructed with three regions. In the middle is the active region where undoped AlGaAsSb layers confine the InGaAsSb QWs. The active region is sandwiched by two heavily doped AlGaAsSb cladding layers which form a pn junction and provides the optical confinement. In Phase 1, the laser structure will be grown InP substrates with a buffer layer to which the AlGaAsSb layers are lattice-matched. Using InP substrates with a buffer layer has demonstrated advantages over GaSb and InAs for the antimonides. They anticipate a major increase in laser wavelength by the use of strained QW structures as compared to conventional antimonide based QW or double heterostructure (DH) lasers. The modification of the density of states in QWs associated with the quantum effects can result in lower threshold current and reduced temperature sensitivity. They will study strain and quantum effects as well as the Auger recombination process, an important nonradiative mechanism in low bandgap materials, in order to optimize their laser design. In Phase I, their design will be implemented, characterized and compared to the model. The Phase I effort will create a firm base for the further development in Phase II. The strained QW approach chosen will allow them to develop this material to cover the laser wavelength range from 6 to 10ªm in later Phases. The growth, processing and packaging capability will be refined and a distributed feedback mechanism will be implemented to improve the mode selectivity for single mode operation in Phase II in order to produce lasers suitable for military and commercial applications. They will also implement the lasers in IR spectroscopic Trace Gas Concentration Monitoring and Analysis system.