High-Performance 1300-1600 nanometer InP-Based VCSELs

0245426Coldren该计划的目的是展示有史以来最高性能的1550 nm VCSEL，使用非常坚固、可制造的、基于InP的技术。它还旨在演示使用此方法的WDM阵列技术以及在1300至1550 nm范围内的可操作性。这项技术基于最近获得专利的VCSEL设计理念[1]，该设计理念已经展示了创纪录的性能，使用了高折射率对比度的As-Sb DBR反射镜以及用于低阻电触点和热提取的InP导电层，所有这些都是晶格匹配的，并在InP衬底上通过单一外延步骤生长[2-4]。然而，在这个计划中，它被提议纳入几个新的和新的概念，这些概念承诺在先前里程碑的基础上实现重大的性能突破。这些概念包括1)用于低损耗横向光学和电流限制的新型介质孔，2)用于减少垂直载流子泄漏的电子势垒，以及3)用于横向载流子限制的器件周围的量子井混合。这些元件将导致输出功率、最高工作温度、壁塞效率和可用波长范围的显著改善，这是未来低成本光网络所希望的。之前由NSF和DARPA资助的工作已经成功地展示了一般方法的巨大前景。最近，在此InP平台上进行的实验表明，与所有不同的单片方法相比，1550 nm VCSEL的总体结果最好[2-4]。这些结果表明，有史以来第一个1550 nm VCSEL具有低于毫安的阈值电流，在室温下发出超过1毫瓦的光。在这种情况下，即使采用非最佳有源区设计和一些额外的光学损耗，它也可以在70C时提供0.2 mW的输出。此外，由于现在了解了这些早期设备中存在的几个局限性，已经确定了建议的改进，初步实验和建模表明了上面所述的“重大性能突破”。这项工作的智力价值来自于其原创性、对知识的贡献、以及PI的经验和基础设施。与拟议技术相关的11项发明已被申请为专利。提出的新型VCSEL设计包括使用新的介质打孔技术来实现横向电流和光学限制，使用电子势垒层来改善高温性能，以及可选地使用一种新的注入和退火程序来选择性地混合外围的量子阱来实现横向载流子限制。以前，人们提出了创建这种VCSEL的WDM阵列的新方法[5]；开发了一种可重复使用的MBE生长工艺，使用与InP晶格匹配的AlGaAsSb化合物来创建低光学损耗、高折射率对比度的DBR反射镜；包括用于低热阻和低阻抗的高导电性InP层；以及开发了结合InP和AlGaInAs的极低电压降隧道结(TJ)，以使仅具有n掺杂接触层的VCSEL能够实现低光损耗和低电阻[6]。这一活动的更广泛影响包括其对降低光通信行业源成本的潜在影响。目前的长波长垂直腔面发射激光器不能提供所需的输出功率，并且它们的工作温度范围有限。这项研究的结果将为1300-1550 nm范围内的低成本技术提供更高的功率、更高的效率和更高的操作温度，这将非常有助于光通信行业从目前的低迷中恢复过来。该项目将为参与其中的研究生提供一个很好的教学工具，他们将需要学习OE设备物理、材料生长和加工以及设备表征的各个方面。

0245426ColdrenThe intent of this program is to demonstrate the highest performance 1550 nm VCSELs ever, using a very robust, manufacturable, InP-based technology. It is also intended to demonstrate WDM array technology using this approach as well as operability in the range between 1300 and 1550 nm. This technology is based on a recently patented VCSEL design philosophy[1] that has already demonstrated record-level performance using high-index-contrast As-Sb DBR mirrors together with InP conductive layers for low resistance electrical contacts and heat extraction, all lattice-matched and grown in a single epitaxial step on an InP substrate[2-4]. However, in this program it is proposed to incorporate several new and novel concepts that promise significant performance breakthroughs on top of the prior milestones. These concepts include the incorporation of novel 1) dielectric apertures for low-loss lateral optical and current confinement, 2) electron barriers for reduced vertical carrier leakage, and 3) quantum-well intermixing around the circumference of the device for lateral carrier confinement. These elements will lead to significant improvements in output power, maximum operating temperature, wall-plug efficiency, and available wavelength range, as desired for future low-cost optical networks.Prior work funded by NSF and DARPA has been successful in demonstrating the huge promise of the general approach. Most recently, experiments on this InP platform demonstrated the best overall 1550nm VCSEL results[2-4] as compared to all of the various monolithic approaches. These results illustrate the first ever 1550 nm VCSEL to have a sub-milliamp threshold current with over a milliwatt of light out at room temperature. And even with a non-optimal active region design and some excess optical loss in this case, it provided 0.2 mW of output at 70C. Moreover, because several limitations that were present in these early devices are now understood, the proposed improvements have been identified, and preliminary experiments and modeling suggest the 'significant performance breakthroughs' indicated above.The intellectual merit of this work derives from its originality, contribution to knowledge, and experience and infrastructure of the PI. Eleven inventions related to the proposed technology have been filed as patents. The proposed novel VCSEL designs include the use of new dielectric-aperturing techniques for both lateral current and optical confinement, an electron barrier layer for improved high-temperature performance, and optionally, a novel implant and anneal procedure to selectively intermix quantum wells on the periphery for lateral carrier confinement. Previously, new approaches for creating WDM arrays of such VCSELs were proposed[5]; a reproducible MBE growth procedure was developed to create low optical loss, high-index contrast DBR mirrors using compounds of AlGaAsSb lattice-matched to InP; high-conductivity InP layers for low thermal and electrical impedance were included; and very low-voltage-drop tunnel junctions (TJs) incorporating InP and AlGaInAs were developed to enable VCSELs with only n-doped contact layers for low optical loss and electrical resistance[6].The broader impacts of this activity include its potential for having a major impact on reducing the cost of sources for the optical communications industry. Current long wavelength VCSELs do not provide the required output power, and their temperature range of operation is limited. Higher-power, higher-efficiency, and higher operating temperatures in a low-cost technology for the 1300 - 1550 nm range will be offered by the results of this research, and this will be very enabling to the optical communications industry in its attempts to recover from its current slump. The project will provide an excellent teaching vehicle for the graduate student involved, who will need to learn various aspects of OE device physics, materials growth and processing, and device characterization.