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

该项目的目标是制作和研究非线性混频激光器：一种新型的中/远红外半导体激光器，它基于最初的概念，即在一个复合的双波长激光腔中通过两个自产生的光场产生差频。注入泵浦激光器具有两个垂直堆叠的有源区，由薄的隧道结分隔，使电流能够串联通过有源区。将实现边缘发射和垂直腔面发射激光器，以及两个对接光学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用对接激光器和量子级联激光器进行了演示。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、无反转的性质，激光阈值可以有效地由带间跃迁上的激光阈值来定义。所提出的非线性混频激光器结合了标准近红外二极管激光器的独特特性(高紧凑性、可靠性、连续波室温工作、低阈值注入泵浦、高效率)和在中/远红外范围(包括太赫兹范围和大气透明窗口)广泛可调谐工作的可能性。由于这种组合，以及在这个范围内缺乏商用的连续波室温半导体激光器，它们有望在污染监测、国防、无线通信、安全系统、化学、生物和医学等领域找到广泛的高要求应用。该项目将产生强大的更广泛的影响。两名研究生将长期参与该项目，并得到补助金的支持。拟议中的两个国家主要研究和教育中心--TAMU和德克萨斯大学奥斯汀分校--的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。调查人员致力于定期组织学生交流，在塔马大学和德克萨斯大学奥斯汀分校之间轮流举办研究学生研讨会，并吸引学生参加科学会议。该项目支持广泛使用多用户设施，如德克萨斯大学奥斯汀分校的MOCVD和MBE外延生长设施，作为大量理工科学生的主要研究和指导场所。从上面的申请清单可以看出，这对社会的好处是显而易见的。

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.