New Types of Mid/Far-Infrared Semiconductor Lasers for CW Room-temperature Operation

该项目的目标是制造和研究非线性混合激光器：一种新型的中/远红外半导体激光器，其基础是在复合双波长激光腔中通过两个自生光场产生差频的原始概念。将开发具有两个垂直堆叠的有源区的注入泵浦激光器，该有源区由薄隧道结隔开，使得电流能够串联地流过有源区。将实现边缘发射和垂直腔面发射激光器，以及具有两个对接光耦合二极管的激光器。非线性自混合的概念已经在我们以前的工作中使用对接激光器以及量子级联激光器进行了证明。双波长激光器将基于全外延，光刻定义的制造技术。由于差频产生的非线性、无反转性质，激光阈值由用于在带间跃迁上激射的低阈值有效地限定。因此，该激光器有望具有低阈值电流密度，从而实现稳定的连续波室温工作。所提出的非线性混频激光器联合收割机结合了标准近红外二极管激光器的独特功能（高紧凑性、可靠性、连续波室温操作、低阈值注入泵浦、高效率），具有在中/远IR范围内广泛可调操作的可能性，包括THz范围和大气透明度窗口。由于这种组合，以及缺乏商业上可用的连续波室温半导体激光器在这个范围内，他们有希望找到一个广泛的高需求的应用在污染监测，国防，无线通信，安全系统，化学，生物学和医学。该项目将产生强大的更广泛的影响。两名研究生将永久参与该项目，并得到赠款的支持。国家两个主要研究和教育中心- TAMU和UT-奥斯汀-的拟议合作为人力资源开发和加强研究和教育基础设施创造了独特的机会。研究人员致力于定期组织学生交流，并在TAMU和UT-奥斯汀之间交替举办研究学生研讨会，并让学生参加科学会议。该项目支持广泛使用多用户设施，如UT-奥斯汀的MOCVD和MBE外延生长设施，这些设施是大量科学和工程学生的主要研究和指导场所。从上述应用清单中可以明显看出对社会的好处。

The goal of the project is the fabrication and study of Nonlinear-Mixing Lasers: a new type of mid/far-IR semiconductor lasers based on the original concept of difference-frequency generation by two self-generated optical fields in a composite, dual-wavelength laser cavity. Injection-pumped lasers with two vertically stacked active regions separated by thin tunnel junction that enables current flow through active regions in series will be developed. The edge-emitting and vertical-cavity surface-emitting lasers will be implemented, as well as lasers with two butt-joint optically-coupled diodes. The concept of nonlinear self-mixing has been already demonstrated in our prior work using butt-joint lasers as well as quantum cascade lasers. The dual wavelength laser will be based on the all-epitaxial, lithographically-defined fabrication technique. Due to the nonlinear, inversionless nature of difference-frequency generation, the laser threshold is effectively defined by a low threshold for lasing on the interband transitions. Thus, the proposed laser is expected to have a low threshold current density, which enables stable continuous-wave room-temperature operation.The proposed Nonlinear-Mixing Lasers combine unique features of standard near-IR diode lasers (high compactness, reliability, continuous-wave room-temperature operation, low threshold injection pumping, high efficiency) with possibility of a widely tunable operation in the mid/far-IR range, including THz range and atmospheric transparency windows. Due to this combination, and the lack of commercially available continuous-wave room-temperature semiconductor lasers in this range, they hold promise to find a wide range of highly demanded applications in pollution monitoring, defense, wireless communications, security systems, chemistry, biology, and medicine.The project will have strong broader impacts. Two graduate students will be involved in the project on a permanent basis and supported by the grant. The proposed collaboration of two major research and education centers of the nation - TAMU and UT-Austin - creates unique opportunity for human resource development and enhancement of the infrastructure for research and education. The Investigators are committed to organize an exchange of students on a regular basis and research student seminars alternating between TAMU and UT-Austin as well as to engage students to participate in scientific meetings. The project supports an extensive use of the multi-user facilities, such as MOCVD and MBE epitaxial growth facilities at the UT-Austin, which serve as major sites of research and mentoring for large number of science and engineering students. Benefits to the society are evident from the above list of applications.