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.
